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Chemical Engineering is a branch of engineering that applies principles of chemistry, physics, mathematics, and biology to design, optimize, and operate processes for the production, transformation, and use of chemicals, materials, and energy. It focuses on the development of efficient and sustainable processes for manufacturing and processing substances.
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The Nalco Water Handbook 2nd Edition
by Hamzah Zuhdi
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RULES OF THUMB FOR CHEMICAL ENGINEERS
by MARIA ROMEU
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Chemical Process Equipment Selection and Design, Third Edition
by vũ An
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Separation Process Principles- Chemical and Biochemical Operations, 3rd Edition
by Evefird Xi
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Coulson and Richardson's Chemical Engineering Vol 2
by anza khawaja
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CHE241 - Lab Report Flowmeter Measurement Apparatus FM101 (2015)
by Nurlina Syahiirah
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INTRODUCTION TO CHEMICAL ENGINEERING THERMODYNAMICS
by Mohammad Hamzah
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Handbook of Offshore Oil and Gas Operations
by Mega Ocean Jaya
No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher... more
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Solving Problems in Food Engineering
by carlos andres
except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known... more
1) Overall mass balance und then the slush is separated in a centrifugal separator into ice crystals ind concentrated juice. An amount of 500 kg/h of liquid is recycled from the separator to the freezer. Calculate the amount of ice that is removed in the separator and the amount of concentrated juice produced. Assume steady state. From eqn (3.8) find J=250 kg/h and then from eqn (3.7) find I= 750 kg/h.
A liquid food at 50 °C is being pumped at a rate of 3 m°/h from a tank A, where the absolute pressure is 12350 Pa, to a tank B, where the absolute pressure is 101325 Pa, through a sanitary pipe 1.5 in nominal diameter with 4.6 x 10-°m surface roughness . The pump is | m below the liquid level in tank A and the discharge in tank B is 3.3 m above the pump. If the length of the pipe in the suction line is 2 m, the discharge line 10 m, and there are one 90° elbow in the suction line, two 90 ° elbows in the discharge line, and one globe valve in the discharge line, calculate the power required, the developed head, and the avail- able Net Positive Suction Head (NPSH). Which of the three pumps that have the characteristic curves given below could be used for this pumping job? The viscosity and the density of the liquid are 0.003 mPas and 1033 kg/m? respec- tively. The efficiency of the pump is 65%. Assume that the level in tank A is constant.
Develop a spreadsheet program to plot the temperature distribution in a plane wall of 4 cm thickness and inner wall surface temperature of 200 °C, at steady state, when a) the thermal conductivity of the wall in W/m °C varies according to the equation k = 0.0325+0.0004T and 250 W/m? of heat are transferred through the wall; and b) the thermal conductivity is constant and equal to the average value for the temperature range of the wall calculated in case a. Calculate the heat transfer rate in case b and compare it to the heat transfer rate of case a.
The physical properties must be calculated at the average water temperature:
Calculate the amount of dry solid per unit surface area:
A liquid food is heated in an unbaffled agitated vessel with a heating jacket. The inside diameter of the vessel is 1 m and the diameter of the flat-bladed paddle agitator is 30 cm. The agitator rotates at N = 60rpm. Calculate the heat transfe1 coefficient at the wall of the jacket. Assume the following physical properties fo1 the liquid food: density 1030 kg/m®, viscosity at the bulk liquid temperature 1.5 mPas, viscosity at the wall temperature 1 mPas, heat capacity 4kl/kg °C. thermal conductivity 0.6W/m°C. The following correlation can be used fot this case. Calculate the Re number (take care with the units):
a Calculate the overall heat transfer coefficient based on the outside surface area of the pipe:
Draw the process diagram: Step 2 Step |
A 211x300 can containing a meat product is heated in a retort. The initial temperature of the can is 50°C, the heat transfer coefficient at the surface is 3000W j m*°C, and the physical properties of the meat product are: k = 0.5W/m°C, cy = 2.85kJ/m°C, and p = 1100kg/m>. Calculate the tem- perature at the geometric center of the can after 30 min if the steam temperature in the retort is 130°C.
that the fruit is spherical; its initial temperature is 25°C; the cold water and the air temperature are 1°C; the diameter of the fruit is 6 cm; the heat transfer coefficient is 1000W / m?°C in the case of hydrocooling, 20W / m? °C in the case of forced air cooling, and 5W/m?°C in the case of room cooling; and the physical properties of the fruit are: k=0.4W/m°C, p= 900kg/m’, Cp = 3.5kI/kg °C. The product development department in a food plant is interested in knowing what shape they should give to a new product for a faster temperature change at the center of the product from 20°C to 90°C. Should the shape be a cube 50mm x 50mm x 50mm, a cylinder with diameter 62.035 mm and length 41.36 mm, or a sphere with diameter 62.035 mm? All these shapes will have
Step |
4) The combined effect of mass transferred in the x, y, and z directions is:
Locate the points on the pressure-enthalpy and the temperature-entropy charts:
Solve eqn (15.1) for q. and find the rate of heat absorbed in the evaporator:
Solve the problem using the spreadsheet program Evaporator.x/s. In the sheet “4-Effect Forward”, insert the data in the yellow cells and follow the instruc- tions. Insert a trial value for the heat transfer area in cells H18, J18, L18 and N18 and iterate until a “FINISH” signal is shown in the control panel. Check if the boiling temperature in cells H23 and N23 is 70 4 t 1°C and 40 4 t 1°C. If not, use another trial value for the heat transfer area and iterate. Repeat this proce- dure until the boiling temperature is equal to the given values. is equipped with a contact condenser with 150 m? heat transfer area for the condensation of the vapors exiting the fourth effect. The overall heat transfer coefficient in the condenser is 2500 W/m2°C. Find the required heat transfer area of each effect and the cooling water flow rate, so that the boiling tempera- ture in the first effect is 70 + 1 °C and in the last effect is 40 + 1 °C. Calculate the steam economy. Assume equal heat transfer area in the effects. Assume that the overall heat transfer coefficient changes as a function of temperature and con- centration according to: U = 400exp(0.03T)exp( — 2.5x,), where U is W/m? °C, T is temperature in °C, and x, is the solids mass fraction.
i) Find the relative humidity curve that passes through point A. i) Read the relative humidity on the relative humidity curve: Read RH = 60%
Step 4
Step | Air is being drawn over the cold surface of the cooling coil of an air conditioning unit. If 10 m?/min enters the air conditioner, calculate the mass flow rate of the condensed moisture, given that the air enters at 20°C and 70% relative humid- ity and exits at 12°C dry bulb temperature and 90% relative humidity. Calcu- late the refrigeration capacity of the coil in W and Btu/h.
aie “ie Find the slope of the curve of X vs t at various time values, or calculate ax vs or 4X vs X from the experimental data.
Fig. A.1_ Moody diagram of the friction factor for fluid flow inside pipes (equivalent roughness ¢, in m, for drawn tubing 1.5 x 10~°, commercial steel 46 x 10~°, galvanized iron 150 x 10~°, cast iron 260 x 10°) Based on Moody LF (1944) T ASME 66. Used with permission
Fig. A.2. Gurney-Lurie chart for a flat plate (1923) Ind Eng Chem 15. Used with permission
Fig. A.3 Gurney-Lurie chart for a long cylinder (1923) Ind Eng Chem 15. Used with permission
Fig. A.4 Gurney-Lurie chart for a sphere (1923) Ind Eng Chem 15. Used with permission
Fig. A.5 Heisler chart for determining the midplane temperature of a flat plate (1947) T ASME 69. Used with permission
Fig. A.6 Heisler chart for determining the centerline temperature of a long cylinder (1947) T ASME 69. Used with permission
Fig. A.7 Heisler chart for determining the center temperature of a sphere (1947) T ASME 69. Used with permission
Fig. A.8 Pressure- enthalpy diagram for HFC 134a with permission from DuPont
Fig. A.9 Pressure- enthalpy diagram for HFC 404a with permission from DuPont
Fig. A.10 Psychrometric chart with permission from Carrier
Table 1.1 Basic units Table 1.2 Derived units
Table 1.3. Conversion factors
Review Questions For a single wall
Table 10.2 Solutions of the unsteady state heat transfer equation for uniform initial tem- perature and both resistances, surface and internal, significant (0.1 <Bi<40) Table 10.3 Unsteady state heat transfer with negligible internal resistance (0.1 < Bi)
Table 13.1 Relations between heat and mass transfer parameters S. Yanniotis, Solving Problems in Food Engineering. © Springer 2008
(continued)
Table A.1 (continued)
Table A.2 First six roots of the equation: 6 tan 6 = Bi
Table A.3 First six roots of the equation: 6 J,(6)-Bi Jo(5) = 0
Table A.4 First six roots of the equation: 6 cot 6 = 1-Bi
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Chemical Engineering Design Principles, Practice and Economics of Plant and Process Design - Copy.pdf
by Sitha Nurfitriani
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Fundamentals of Petroleum and Petrochemical Engineering
by Marisol Ojeda
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Free Download Water Wastewater Calculations Manual
by Engneer Ahmed Kamel
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The Wiley Encyclopedia of Packaging Technology, Third Edition
by aulia damayanti
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Petroleum Refining Technology and Economics Fourth Edition
by adelson perez
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Elements of Chemical Reactor Engineering_4th (Soution Manual)-Fogler.pdf
by Dian Mata
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CHEMICAL ENGINEERING Solutions to the Problems in Chemical Engineering Volume 1
by NaNu Percy
PROBLEM 1.1 98% sulphuric acid of viscosity 0.025 N s/m 2 and density 1840 kg/m 3 is pumped at 685 cm 3 /s through a 25 mm line. Calculate the value of the Reynolds number. Solution Cross-sectional area of line D /4 0.025 2 D 0.00049 m 2... more
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Heat Transfer-Application-for-the-Practicing-Engineer-by-Louise-Theodore
by Trần Minh Nhật
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Biodegradation of Synthetic and Natural Plastic by Microorganisms
by sciepub.com SciEP
Plastic disposal is one of the greatest problems facing the environment today, as vast amounts of synthetic plastic remain non degradable. A number of microorganisms have the ability to degrade different types of plastic under suitable... more
Figure 1. The percentage of municipal solid wastes in Makah city according to the Holy Makah Municipality report (2014) Plastic is a synthetic polymer. It consists of carbon, hyd rogen, silicon, oxygen, chloride and nitrogen. It is derived from different sources such as oil, coal and natural gas and . Plastics are extensively used because of their stability durability. They are different types such as polyethylene (PE), Poly Ethylene Terephthalate (PET), nylons, Poly-Propylene (PP), Polystyrene (PS), Polyvinyl Chl oride (PVC), and Polyurethane (PUR) [1]. Due to the In Saudi Arabia, approximately 12 million tons of municipal solid wastes are produced annually, consisting of 40% organic wastes, 20% paper wastes, and 12-15% of plastic products [3]. According to the 2014 statistics of the Holy Mecca Municipality, about 82,933 tons of municipal solid wastes were produced, 26% of which were plastics [4]. Figure 1 illustrates the percentages of the different types of solid wastes produced by this municipality in 2014.
Figure 2. Structure of biodegradable plastic polyhydroxyalkanoates (PHA) and its derivatives poly(3-hydroxybutyrate) PHB and poly(3-hydroxybutryrate - co-3-hydroxyvalerate) Adapted from Shah et al., 2007 [18]
Figure 3. Chemical structures of petrochemical plastics Polyethylene (PE), Polyvinyl chloride (PVC), Polypropylene (PP), Polystyrene (PS) Polyethylene Terephthalate (PET) and Polyurethane (PU). Adapted from Shah et al., 2008 [18]
Anaerobic and aerobic biodegradation mechanism pathways are given in Figure 5. Extracellular and intracellular depolymerize enzymes are actively involved in biological degradation of polymers. During degradation, microbial exoenzymes break down complex polymers, yielding short chains or smaller molecules like oligomers, dimers and monomers. These molecules are small enough to be water-soluble, and can pass through the semi-permeable outer bacterial membranes to be used as carbon and energy sources. This initial process of breaking down polymers is called depolymerization; and when the end products are inorganic species (e.g., CO2, H,O, or CHy), the degradation is called mineralization [24]. Also known as aerobic respiration, aerobic biodegradation is an important part of the natural attenuation of contaminants in many hazardous waste sites. Aerobic microbes use oxygen as an electron acceptor, and break down organic chemicals into smaller organic compounds. CO, and water are the by-products of this process [23]. Figure 5. The General Mechanism of Plastic biodegradation under Aerobic Conditions [24]
Figure 6. Reaction pathways during biodegradation of polymers
Polypropylene is a thermoplastic that is commonly used for plastic mouldings, stationary folders, packaging materials, plastic tubs, non-absorbable sutures, diapers, etc. It can be degraded by exposure to ultraviolet radiation from sunlight, and it can also be oxidized at high temperatures. The possibility of degrading PP with microorganisms has also been investigated [33]. Studies reported on biodegradation of PP, many microbial communities such as certain fungal species like Aspergillus niger and bacteria such as Pseudomonas and Vibrio have been reported to biodegrade PP. A decrease in viscosity and the formation of new groups, namely carbonyl and carboxyl, were observed during the degradation process [34]. Figure 7. The Mechanism of biodegradation of polyethylene. Adapted from Vasile, 1993 [32]
Synthetic Plastics are classified according characteristics of the reactions by which they are to the formed. If all atoms in the monomers are incorporated into a polymer, the polymer is called an addition po ymer; if some monomer atoms are released into small molecules, such as water, the polymer is called a cond ensation polymer. Most addition polymers are made from monomers containing a double bond between carbon atoms. Such monomers are called olefins, and most commercial addition polymers are po yolefins. Plastics are relatively very low-cost, durable, and very easy to manufacture. The following table (Figure 4) describes some commonly-used plastics and their applications [19].
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Chemistry of Petrochemical processes MATAR
by Abraham Guerrero
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plant engineering
by aqib bagong
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iii MANUFACTURE OF FORMALDEHYDE FROM METHANOL A PROJECT REPORT
by Payam Parvasi
We also thank our project co-ordinater Mrs.K.Kasturi,B.Tech, for her valuable advice and encouragement.
hydrate and bismelamines. 14. HEALTH AND SAFETY CONSIDERATIONS
International Agency for Research on Cancer(IARC).Lifetime inhalation studies with irritation does not generally occur until concentrations of | ppm, based on controlled
(Table 4) Formaldehyde manufacturing plant are furnished below:
INDIRECT COST FACTOR (Table 6)
Fixed capital investment in process area, IF = Direct plant cost
Table 7: Capital investment in the auxillary services = (Fixed capital investment in process
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Coulson richardson's chemical engineering volume 2 solution manual soln
by Felipe Aguilar
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CLASIFICACIÓN DE LOS FLUIDOS NO-NEWTONIANOS
by Luis Ángel Sánchez Madera
FLUJO DE FLUIDOS PROFESOR ORTIZ BAUTISTA DOMINGA POR LUIS ÁNGEL SÁNCHEZ MADERA CLASIFICACIÓN DE LOS FLUIDOS NO-NEWTONIANOS FLUJO DE FLUIDOS GRUPO: 4502
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PIPESIM Fundamentals Training and Exercise Guide
by Rolando Cortazar
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CONCEPTUAL DESIGN OF CHEMICAL PROCESSES
by Samuel Ivanovic
is currently a professor of chemical engineering at the University of Massachusclls. Previously he taught at the University of Rochester and at the University of [klaware. Before entering leaching, he spent five years at ARea, working on... more
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Introduction to Engineering Material and their Applications
by Ahmad Mukhtar
The topic of study report relates to"Introduction to Engineering Material and their
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Practical Case Study INDUSTRIAL EFFLUENTS AND THEIR IMPACT ON WATER QUALITY OF RECEIVING RIVERS IN NIGERIA
by Ome Achi
Industrial wastewaters entering a water body represent a heavy source of environmental pollution in Nigerian rivers. It affects both the water quality as well as the microbial and aquatic flora. With competing demands on limited water... more
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Tipos de Reactores con sus características
by Cristian Gómez
Se resume las principales características de los reactores y se proporciona fotografías a nivel industrial de estos equipos. La información es una adaptación de la versión en inglés que se encuentra en:... more
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Heat Transfer Principles And Applications by BK dutta
by anza khawaja
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Ahmed, Tarek - Reservoir Engineering Handbook
by luqman fahmi
Nearly all naturally occurring hydrocarbon systems contain a quantity of heavy fractions that are not well defined and are not mixtures of discretely identified components. These heavy fractions are often lumped together and identified as... more
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Modeling Analysis and Optimization of Process.and Energy Systems
by Essid abou hligha
Energy costs affect the profitability of virtually every process. This book provides a unified platform for process improvement through the analysis of both the energy demand side—the processing plant—and the energy supply side—... more
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MICROBIAL BIOTECHNOLOGY: Fundamentals of Applied Microbiology, Second Edition
by Irene del Vigo Soto
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Does Active Learning Work? A Review of the Research
by Michael Prince

2004

This study examines the evidence for the effectiveness of active learning. It defines the common forms of active learning most relevant for engineering faculty and critically examines the core element of each method. It is found that... more
Figure 1. Active-engagement vs. traditional instruction for im- proving students’ conceptual understanding of basic physics concepts (taken from Laws et al., 1999)
Table 2. Collaborative vs. competitive learning: Reported effect size of the improvement tn different learning outcomes
Table 3. Effect sizes for academic achievement associated with various aspects of problem-based learning. Beyond producing positive student attitudes, the effects of PBL are less generally accepted, though other supporting data do exist. Vernon and Blake [19], for example, present evidence that there is a statistically significant improvement of PBL on students’ clinical performance with an effect size of 0.28. However, Colliver [22] points out that this is influenced strongly by one outlying study with a positive effect size of 2.11, which skews the data. There is also evi- dence that PBL improves the long-term retention of knowledge compared to traditional instruction [51-53]. Evidence also suggests that PBL promotes better study habits among students. As one might expect from an approach that requires more independence from students, PBL has frequently been shown to increase library
Table 1. Collaborative vs. individualistic learning: Reported effect size of the improvement in different learning outcome: The importance of student engagement is widely accepted and there is considerable evidence to support the effectiveness of student engagement on a broad range of learning outcomes. Astin [38] What do these results mean in real terms instead of effect sizes, which are sometimes difficult to interpret? With respect to academic achievement, the lowest of the three studies cited would move a
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Environmental Engineering Dictionary and Directory
by Tuấn Nghiêm
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PDF methods for turbulent reactive flows
by Driss Lazar

1985, Progress in Energy and Combustion Science

The aim of the methods described is to calculate the properties of turbulent reactive flow fields. At each point in the flow field, a complete statistical description of the state of the fluid is provided by the velocity-composition joint... more
Fic. 2.1. Sketch of a turbulent mixing layer showing locations of (a) fully turbulent flow, (b) intermittent flow, (c} non-turbulent flow. closely related to turbulence by Lumley*® and Panchev*’ can be used as general references, but these do not contain all the necessary results.
The probability density function (pdf) f,(w) of the random variable ¢ is the derivative of the distribution 2.4. Probability Density Function
Fic. 2.8. Distribution functions and pdf's in a turbulent flow: (a) fully turbulent region: (b) intermittent region; (c) non-turbulent region.
Fic. 2.9. (a) Distribution functions against y: dashed line F,(W); solid line F,y(w). (b) PDF's against y: dashed line J,(W); vertical lines (representing delta functions of magni- tude 0.05) fy (w).
Fic. 2.10. Joint-normal pdf, and 100 sample points. The probability of a sample point being inside each ellipse is (from the inside outward) 0.2, 0.4, 0.6, 0.8 and 0.99.
Fic. 2.11. Joint-normal pdf: f,,{}. w) against V for y = 0.3. 0.4. 0.5. 0.6 and 0.7.
Fic. 2.12. The event A (Eq. 2.126) in: (a) V-y space, (b) g-h space. is sketched as a region of V-w space on Fig. 2.12a and as a region of g-h space in Fig. 2.12b. With f,,(G, A) being the joint pdf of g and h, the probability of the event A is
where the material derivative (the rate of change following the fluid) is The evolution of the reactive flow field is governed by the conservation equations of mass, momentum, chemical species and enthalpy®*°°: where m denotes the set of species mass fractions.
Fic. 3.1. Reaction path in augmented composition space. quiescent, reactive gas mixture, which at time r, has the composition $(t)) = 6). According to Eq. (3.20), as reaction takes place, the composition evolves by
Fic. 4.1. Fluid particle paths and material element volume change in x,—x,-t space. Figure 4.1 is a sketch of fluid particle paths (or pathlines) in x—-t space for a two-dimensional flow. The fluid particle which is initially at xo follows the fluid particle path to reach x*(x,t) at time ¢. The fluid particles which initially occupy the (two-dimensional) volume d¥(to), at time t occupy the larger volume d¥‘(). This volume expansion is due to a decrease in density, Eq. (4.18).
Fic. 4.2. Fluid particle paths in the augmented state space. the same turbulent flow generate different particle paths in the augmented state space.
The second step follows since an infinitesimal change in J* ofdU* has the same effect on the delta function asa hange in V of dV = —dU?;; the third step follows ecause OU;* /dt is not a function of V; and the final esult is obtained by using Eq. (4.13). The evolution equation for f; is derived by differentiating Eq. (4.27) with respect to time. In order to do this we need to determine the derivatives of the delta functions. For the temporal derivative of 6(U* (Xo, t)— V) we have
Differentiating Eq. (4.27) with respect to time (noting that only f) is a function of t) we obtain where f,,f,,f” and f have the same arguments as in Eq. (4.27), and Eqs (4.11) and (4.14) have been used to eliminate 0x * /dt and 0@* /ét. Now for the term in A; we have (see Eq. 2.150)
Fic. 4.3. Conditional path from (Vo, Wo, Xo) at t = fy in the augmented state space. change (a,@,0) is not a random variable: it is the conditional expectation of the rate of change of fluid particles with the same state.
Fic. 4.7. Sample of the Weiner process W,. ts < ty, [W,, —W,,] and [W,, — W,,] are independent Gaussian random variables with zero means and variances (t, —t,) and (t, — 1) respectively.+ The increment
Both stochastic processes considered are Markov processes. That is, given the current state U*(r), the future state U*(t,) is independent of the past U*(t)) (to <t <t,). Consequently,’® the conditional pdf SEV, W,X5t|Vo, Wo. Xo) evolves according to the same evolution equation as the unconditional pdf, Eq. (4.103). In fact, the conditional pdf can be determined as the solution of this equation with the initial condition
Although f* and #¥* have distinctly different properties, it may be seen that their evolution equations (Eqs 4.103 and 4.105) are identical. 4.7. Normalization, Mean Continuity and Pressure
The mean pressure <p) is obtained from the Poisson equation, (Eq. 4.129), and p(y) and S(y) are known functions. Thus all the terms on the left-hand side of Eq. (5.1) are in closed form. The three conditional expectations containing 1,,, p’ and J? need to be modelled while the remaining terms are known. Before considering the terms to be modelled, we emphasize that no modelling is needed for the terms pertaining to reaction, the mean pressure gradient, buoyancy, or transport in physical space.
<$'* independent of N.) All the well-behaved deter- ministic models proposed?*:?®83-85 contain an integral over composition space such as that in Eq. (5.40). In a numerical solution, these integrals are computationally-expensive to perform, and con- sequently it is advantageous to use the stochastic model instead. The distinct behaviour of fluid particles, stochastic particles and conditional particles is illustrated in Fig. 5.1. Fluid particle paths in w-space (Fig. 5.la) are erratic with variations on all time scales down to the Kolmogorov scale. A stochastic particle path (Fig. 5.1b) is discontinuous since ¢*™ is a piecewise con- stant function of t: the duration of the intervals of constancy is of order t. Conditional paths (Fig. 5.1c) are uniquely determined, smooth and continuous. In each case the particle paths converge since the variance ¢@’”» decreases with time.
Figure 5.3 illustrates the mixing process given by Eq. Fic. 5.3. Effect of mixing on the stochastic particles 6*'”) and ¢*: © before mixing, @ after mixing. o*(t +t) = O*™(t),n # pandn#q. (5.49)
Fic. 5.4. Samples of ¢*(t) given by the Langevin model with (a) B = 2.0, (b) B = 0.2. p*(t) and f(t) shown on Fig. 5.1. The behavior of p*(t) according to the Langevin model is similar to hat of fluid particles. However #*(t) has fluctuation yn all time scales whereas ¢ * (t) has fluctuations only iown to the Kolmogorov time scale.
Fic. 5.5. Effect of mixing on the stochastic particles U*”) and U*: © before mixing, @ after mixing.
Fic. 5.6. Effect of stochastic reorientation showing that the average velocity U and the velocity difference AU are un- affected: O before reorientation, @ after reorientation. When the stochastic mixing model and the stochastic reorientation model are used simultaneously, the net effect is the sum of the two effects (Eqs 5.91 and 5.94). Thus, the stochastic models cause the Reynolds Stresses to evolve according to Rotta’s model (Eq. 5.80).
Fic. 5.7. Sketch showing points x and y in region R.
The only other obvious source of information that can be used to determine the coefficients is experi- mental data on the evolution of Reynolds stresses in homogeneous turbulence. But when the modelled Reynolds stress equation is deduced from Eq. (5.161), the coefficients appear in groups—only four of which are linearly independent of Eqs (5.166-167). Thus two degrees of indeterminacy remain. Haworth and Pope?* remove this indeterminacy by setting
The principal influence of inhomogeneity is to cause convective transport in physical space. This effect appears in closed form in the joint pdf equation through the term V,0f/dx,. In contrast, in second- order closures, this term gives rise to the correlations (uu ju», u;uj;o,> and <u,o,¢,> which are generally modelled by gradient diffusion. It is emphasized that, in the joint pdf equation, the convective term is in closed form and therefore no ,gradient diffusion models are needed.
sometimes non-turbulent.'°° Consider a _ high Reynolds number jet which transports a conserved passive scalar $,(x,t), where y = +1. At the jet exit ¢, is positive, while in the non-turbulent, irrotational fluid remote from the jet @, is zero. As the Reynolds number tends to infinity, the condition ¢,(x,t) > 0 can be used as an indicator of turbulent fluid. That is, if $,(%,t) > 0, the fluid is in turbulent motion, if ¢,(x, t) = 0, the fluid is in irrotational, non-turbulent motion. The intermittency factor y(x,t) is defined as the probability of the fluid at (x, r) being turbulent. In terms of the indicator ¢,, the intermittency factor is
Fic. 5.9. Density p and reaction rate S against # (arbitrary scale). Let the single scalar @ be the progress variable (normally denoted by c°*) that is zero in the unburnt In the stochastic mixing model for f,(y), it is assumed that the rate of mixing is inversely propor- tional to the turbulent time scale t. This assumption (modified by the comments of Section 5.7.3) is valid provided that the steepest gradients—which provide the dominant contribution to <'V7|w> —are caused by turbulent straining. But rapid reactions can also produce steep composition gradients. This effect is studied in more detail for an idealised premixed turbulent flame.
Fic. 5.11. Quantity A(®) against ®, Eq. (5.216) (arbitrary scale).
Fic. 5.10. Premixed laminar flame profile ®(x,) against x,. This result has been obtained for a stationary flame normal to the x, coordinate direction with the origin chosen so that ®(0) = 1/2. But the left-hand side of Eq. (5.215) is a scalar that depends only on gradients of @—it is unaffected by an arbitrary reorientation, shift, or translation of the coordinate system. Conse-
Corresponding to Eq. (6.24), the evolution equations for stochastic particle properties are: + There are several solutions to the problem presented by having an odd number of particles in a cell—but this is a computational detail.
In this section, the determination of means is considered by reference to a one-dimensional example. It is shown that the straight-forward method of approximating means by ensemble averages over cells is hopelessly inaccurate, especially for derivatives and pdf’s. But the method of least-squares cubic splines provides a more accurate alternative. An alternative method of determining means is least- squares cubic splines (de Boor!?°). A cubic spline is a piecewise cubic polynomial which is continuous and has continuous first and second derivatives. The x-axis is divided into L equal intervals, and within each interval the function (ie. (@>) is approximated by a cubic polynomial. Thus there are 4L polynomial coef- ficients. At the (L — 1) points between the L intervals, the function and its first two derivatives are continuous.
Fic. 6.3. Term d?<(x)>/dx? against x: @ from least- squares cubic spline; ————— exact result.
Fic. 6.4. Histogram (with interval Ay = 0.25) compared with the pdf f,(w; 1/2).
Fic. 6.5. Histogram (with interval Ay = 0.1) compared with the pdf f,(; 1/2).
Fic. 6.8. Sketch of a two-dimensional mixing layer showing a fluid particle path.
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Schneider Electric Wiring Diagram Book
by Engineer Bilal Nasir
This book contains examples of control circuits, motor starting switches, and wiring diagrams for ac manual starters, drum switches, starters, contactors, relays, limit switches, and lighting contactors.
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WATER TREATMENT Edited by Walid Elshorbagy and Rezaul Kabir Chowdhury2883 Edited by Walid Elshorbagy and Rezaul Kabir Chowdhury
by king wei and 
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R. Chowdhury
Some Details of Mathematical Modelling of Effluents in Rivers Downstream of aWWTP 43
Table 4. Characteristic times
Some Details of Mathematical Modelling of Effluents in Rivers Downstream of aWWTP 47
Figure 1. Data requirements guidelines for water treatment processes as a component of integrated urban water management (based on Fletcher et al., 2008)
Figure 2. Interrelationships between water and energy (U.S. Department of Energy, 2006) Table 3 shows average water consumption for different energy production and power generation techniques. The data presented in Table 3 are predominantly for the United States of America and were compiled by Younos et al. (2009). Natural gas production is found to be the most water efficient. Corn-based and soy-based biofuel production
Figure 3. A schematic diagram of SCADA system in water treatment process (based on Baxter et al., 2001)
As shown in Fig. 1, the feasible region is an arc. If the initial point is X°=(2, 0), then it needs to move through the are —X7 — X3 — X} + 4 = 0, and finally converges at the optimal point X* = (2 /V2,2/V2). The point moves along the line and travels a very short way at first and must enter the feasible region. In the next step, the point moves forward in a straight line direction and repeats the same pull-in operations. However, this process wastes much computational time, because the convergence rate is too slow. Therefore, a new concept of tolerance based on the work of Paviani and Himmeblau is proposed in this studv [7.8].
Figure 3. The quasi-feasible region obtained by combining all the constraints.
Figure 4. Flowchart of the multiplier method with the concept of tolerance.
Since the objective function excluded the probability item, it is not convertible. The following Constraints are used. The total alkalinity for coagulation is presented as follows:
Input values represent phosphorous reserves and potential for bioavailable phosphorous forms, while output values represent used bioavailable phosphorous which is further incorporated in plant body. Positive difference confirms that it is not possible to remediate water and whole amount of (active) sediment in one year. Roughly, designed wetland is capable of additional water treatment and remediation of nearly one third of sediment active layer. Accordingly, in addition to water treatment, designed wetland will gradually remediate deposited sediment as well.
Table 1. Key parameters of importance in produced water treatments !!]
Figure 3. The phase composition of zeolite tuffs from different deposits
Figure 1. Number of patents for clinoptilolite (CLI) and mordenite (MOR), (The last ten years) [15]. Numerous and excellent research results in the last 10 years have shown that natural zeolites have practical use, which is confirmed by a large number of patents, especially for the two naturally occurring zeolite minerals: clinoptilolite and modernite shown in Figure 1. The number of patents is substantial for both zeolite types, which gives a clear notice that the interest of researcher in natural zeolites is strongly encouraged by the commercial sector covering the use in households or in industrial/large-scale processes and treatments. covering the use in households or in industrial/large-scale processes and treatments.
Figure 2. Binding of building units (PBU and SBU) in three-dimensional zeolite- clinoptilolite structure.
The effluent water quality of the selected existing plant should be corrosive in some respects. If this constraint is not neglected in the structural constraints, a feasible solution for this model is not available, and thus the sensitivity analysis is necessary to make the conclusion significant and meaningful. The following equations are established using a =0.25: For the alum dosage for coagulation:
There are a number of directives to protect the environment, for example, in the EU see [1], [2]. Implementation of guidelines in accordance with these directives is based on environmental monitoring. Modelling based on existing data could look to reduce the necessary costs required for environmental monitoring in the future. This chapter was included in this book to reflect the adverse impacts of poor-treated and/or accidentally untreated water on nearby water bodies. Figure 1 shows an idealised sketch of mixing of pollutants in the river downstream of the outfall (0 m) of a wastewater treatment plant (WWTP). In general four distinct zones exist downstream of the orifice. The first zone is a zone with background concentration. The second zone is a 3D mixing zone, the third zone is a 2D mixing zone and the fourth zone is a 1D mixing zone. In the initially three-dimensional mixing process (until the location where complete vertical mixing takes place) the drop-off of the maximum mass concentrationis relatively fast, Cina ~ x1, while it occurs more environmental monitoring. Modelling based on existing data could look to reduce the
, where x is the distance between source and monitoring station [m]; t is the time [s]; Ur is the retarded velocity [m.s']; t is the duration of the continuous input [s]; Ex is the longitudinal dispersion coefficient [m?.s™]; erfc is the complimentary error function and K is coefficient [dimensionless]. It was convenient to define dimensionless coefficient K for computation as follows: if t< t then K = 0; if t> t then K = 1. Numerous studies on longitudinal dispersion have been conducted over the past few decades. Fick's second law predicts how diffusion causes the concentration to change with time. In actuality, immobile- flow zones (dead zones) may invalidate Fick’s law. Chatwin [12] developed a method for determining longitudinal dispersion intended to address the problem of non-Fickian behaviour. Technically, the Chatwin’s method is only really valid for impulse releases, but it does provide a reasonable approximation for longitudinal dispersion for pulse and continuous releases [13]. Chatwin’s values b can be computed by equation
Figure 2. Water quality model downstream of Arlington WWTP - calibration procedure Calibration of the CIT model to the tracer study results produced a transverse mixing coefficient constant equal to 0.408 (see Figure 2). The closeness of approach of model CIT values to field values was computed using Equation (6). Resulting value of CIT model was about the same as resulting value of RIVPLUM 5 model and within the range of experiments reported by [8], from which CIT and RIVPLUM5 were developed. Although physical processes play a large role in determining the fate of solutes, chemical and biological processes may be equally important. We would like to describe results of modelling for non-conservative substances now. The next fictive example shows possibility of investigating the impacts of different effluent quality using the CIT developer model to
Figure 3. Centreline excess concentration above ambient background concentration Table 3. Fictive field values and computing DF, VFe and F values xs — the difference between effective and real distance [m].
Figure 4. Regression analysis
Figure 6. Comparison between the shape of toxic index curve and the shape of model concentration ratio curve at Bohumin station on 9 Januarv 2012.
After fitting a straight line through the Chatwin’s values we obtained value b* equal to 862.23 s°> (see Figure 7). The Equation (11) allows for solution of the longitudinal dispersion coefficient, provided that the plot against early-time data reasonably falls as a straight line. The late-time data will depart from the straight line due to non-Fickian dispersion characteristics (e.g., dead zones). For the distance of 11,600 m we calculated a longitudinal dispersion coefficient 45.25 m?.s! using Equation (11). Ratio Rc was computed using Equation (9). Duration of accidental leakage t was estimated so, that the shape of the Rc curve in Figure 6 is about the same as the shape of the toxic index curve. The potential source of accidental leakage could be at the bank of the Odra River approximately 11,600 m upstream of the sampling station, or at the bank of any tributary within this distance. Figure 7. Chatwin’s analysis
(Carp et. al., 2004). Many semiconductors such as TiO2 (Lazau, 2011), ZnO (Daneshvar et al., 2007), ZrO2 (Lopez et al. 2007), CdS (Yingchun, 2011), MoSz (Kun Hong, 2011), Fe2Os (Seiji, 2009) and WOs (Yuji, 2011) have been examined and used as photocatalysts for the degradation of organic contaminants. TiOz is most preferred one due to its chemical and biological inertness, high photocatalytic activity, photodurability, mechanical robustness and cheapness. Thus, these materials were used in the degradation of phenol, 1,4- dichlorobenzene (Papp et al., 1993),methanol (Nobuaki et. al., 2007), azo dye (Daneshvar, 2003), trichloromethane, hexachloro cyclohexane (Byrappa et. al., 2002 ), trichloroethylene and dichloropropionic acid (Nikola, 2001). To avoid the problem of filtration, many methods were proposed to immobilize the photocatalysts, but in these conditions the photocatalyst is expected to be used for a relatively long time, especially for industrial applications (Venkata, 2004). Various substrates have been used as a catalyst support for the photocatalytic degradation of polluted water. For example glass materials: glass mesh, glass fabric, glass wool, glass beads and glass reactors were very commonly used as a support for titania. Other uncommon materials such as microporous cellulosic membranes, alumina clays, ceramic membranes, monoliths , zeolites , and even stainless steel were also experimented as a support for TiO2 (Gianluca, 2008). Figure 1. Classification of advanced oxidation processes
Figure 2. a. PMR utilizing photo-catalyst in suspension: irradiation of the membrane module (Mozia S., 2010), b. PMR utilizing photo-catalyst in suspension: irradiation of the feed tank (Mozia S., 2010)
Figure 3. Asymmetric photocatalytic membranes (Bosc et al., 2005) 5. Conclusion
Figure 5. SEM of zeolite tuffs from Donje Jesenje (a), Vranjska Banja (b), Brus (c) and Strezovce (d). Magnification of app. 20.000x was used in the measurements. Beside the typical plate-like morphology of clinoptilolite crystals, some fiber-like particles of mordenite could be also observed in all four samples.
Chemical modification with inorganic salts (NaCl, CaClz, BaClz, NH4Cl, FeCls) or a cationi surfactant (hexsadecyltri-methylammonium (HDTMA) - bromide) give to improve zeolit properties and increase its efficiency in water treatment [19, 31-38]. For successfu modification high-concentration solutions of inorganic salts on the surface of zeolite i significant as shown in Figure 6. Under normal conditions, large cavities and entries to th channels inside the zeolite framework are filled with water molecules forming hydratiot spheres around exchangeable cationic (Figure 6-A). After the contact of zeolite with a1 inorganic salt solution such as NaCl, exchange of cations (H* or Na‘) from solution witl exchangeable cations (Na*, K*, Ca**, Mg?*) from the zeolite framework occurs (Figure 6-B) To remove anions from the water, zeolite surface has to be modified with a solution o inorganic salts (for example FeCls) whose adsorption on the zeolite surface leads to th formation of oxi-hydroxides, which then form stable complexes with anions in solution. Thi modification can result in — to a smaller or greater extent — the creation of an adsorptiot layer on zeolite surface and modification of surface charge on zeolite surface (from negativ to positive) (Figure 6-C) [39,40]. Specific surface area (BET) of natural and modified zeolit (deposits from Croatia and Serbia) after pre-treatment with inorganic salts is shown in Table 3 Figure 6. Zeolite particles in natural and modified zeolites (Na and Fe forms of clinoptilolite from the deposit V. Banja, Serbia) and SEM image of zeolite surface after the implementation of chemical modification.
Figure 7. Loss of mass for natural and Fe-modified and Na-modified zeolite by the DTG method. Table 4. Structural stability of some natural zeolites [16].
can be increased by intensive mixing of the solution, with increasing solution temperature and concentration. Rate of diffusion through macro and micro pores can be increased by reducing the grain size and concentration of the solution. It is therefore necessary to assess the degree of the ion-exchanging process, which is important for the overall process of ion exchange and hence affects its rate [50].
Figure 9. The uptake of some cations from water solution by natural zeolites from different deposits The removal efficiency of metal ions by natural zeolite depends on the quantity and exchange capacity as well as the presence of other cations and anions in the treated water. With increasing concentration of metal ions in water the removal efficiency increases of these ions using natural zeolite (from 500 mg/L to 1 g/L). Natural and modified zeolites are efficient at low concentrations of different metal ions like Zn?* (concentration from 1 to 5 mg/L) and Fe* (concentrations from 0.2 to 2.0 mg/L) about 50-60%. In many studies revealed the values of the maximum capacity adsorption, Qmax for metal ions removal from synthetic and real water. On Figure 9 Qmax values on cations uptake from water by natural zeolites from different deposits are summarized [76].
On the other hand, several anions (e.g. acetate, chloride, nitrate, phosphate or sulphate) have been witnessed as interfering with arsenate sorption. For arsenic ions binding on iron modified zeolite, the process was irreversible, i.e. stable complexes of arsenic and iron occurred, which is very important for permanent removal of arsenic ions from water solutions.
Figure 12. Scheme of drinking water production plant (A) and pilot plant “filter guards” (B) (NZ-, MNZ-CRO natural and modified zeolite from Croatia; NZ-, MNZ-SRB natural and modified zeolite from Serbia) [102]. Two examples from the Eastern Croatia show a successful application of research results < a pilot plant for potable water. The ground water from the Valpovo region was previousl treated by aeration and sand filtration for the removal of iron, manganese, ammonium an other present pollutants. The physical and chemical parameters of the ground water an ammonium concentration were determined in the ground water after the pre-treatment. Th ammonium sorption efficiency of 100% was obtained after 10 to 90 h with the use of MNZ SRB, but it was sharply decreased after 70 h with use of NZ-CRO or MNZ-CRO (Figure 12).
Figure 1. Scheme of front view of MF module. 2.3.1. Evaluation of permeate flux and fouling percentage of membranes for MF and CFM- MF processes
Figure 2. Membrane-filtration technique, with mechanical extraction and elution (a), analysis by direct immunofluorescence with Merifluor Kit (b) and Cryptosporidium spp. (left) e Giardia spp. (right) visualized in immunofluorescence.
For the MF process with raw water, that is, without previous treatment (coagulation/ flocculation), permeate flux ranged from 157 to 187 L/hm? for water samples of turbidity from 150 to 450 NTU. In the combined process (CFM-MF), permeate flux ranged from 157 to 226 L/hm? for water samples with initial turbidity of 150 to 350 NTU. Samples of 450 NTU presented the lowest permeate flux, 91 L/hm?, on average (Nishi, 2011). This may be due to the presence of a greater number of particles that can cause the process of concentration polarization and due to superposition of various fouling mechanisms in the membrane, which may cause the decrease of the permeate flux (Stopka et al., 2001). and on membrane integrity. In another study, MF membranes with average pore size of 0.2 uum resulted in significant removal of particles that were the same size as Giardia cysts (5-15 tum). Log removal was, on average, 3.3 to 4.4. The removal of particles that were the same size as Cryptosporidium oocysts (2-5 um) was lower, 2.3 to 3.5 log removal. These removals were obtained according to the concentration of (00)cysts used for artificial contamination of water and proved to be independent of the membrane flux (114-170 L/hm?) (Karimi et al., 1999).
Figure 4. Percentage of fouling for the MF process with superficial water (SW) and water coagulated/flocculated with moringa (CFM) with initial turbidity from 150 to 450 NTU. It is observed that the MF process with raw water showed higher percentages of fouling ranging from 6.13 to 56.32% when compared with the combined process of coagulation flocculation with moringa followed by MF, which presented percentages of fouling fron 7.48 to 40.9% (Nishi , 2011). This reduction in membrane fouling when using the process o coagulation/flocculation as pretreatment was also observed in other studies. Madrona (2010 used coagulation/ flocculation with moringa, followed by MF with ceramic membranes witl porosity of 0.1 and 0.2 um, for the treatment of surface water and observed foulins percentages of around 94% during the filtration of raw water and slightly lower values around 88%, when water previously coagulated/flocculated with moringa was filtered Carroll et al. (2000) used polypropylene hollow fiber MF membrane to filter surface wate from the Moorabool River, Australia, and observed fouling percentages of 80% for wate without pretreatment and 50% for water pretreated by coagulation with alum.
To fully clean the filter media without forming dead zones, mud balls, media encrustation, and boiled media spots, even distribution of air and water during backwashing is critical. Fundamentally, there are two types of designs for simultaneous air and water distribution, nozzles and underdrain (with integrated dual channels). Nozzles (Figure 1) usually have slot sizes in the range 0.25-0.5 mm to minimize the risk of sand penetration. Nozzle arrangement density on the floor depends on the type of nozzles and is greater than about 35 nozzles/m? (Ratnayaka et al. 2009). However, the design of nozzle slots needs to be considered carefully to prevent fouling. There are several other underdrain systems, mostly of proprietary designs, successfully used in many parts of the world. An example is the design by Leopold (a Xylem brand) which comprises underdrain blocks (each block approximately 1 foot x1 foot x4 feet), formed from high-density polyethylene (HDPE), which snap lock together to form water resistant long laterals (Figure 2). The blocks incorporate a dual lateral design with a water recovery channel that ensures uniform distribution of concurrent air and water even over laterals up to 42 feet or 12.8 m. The blocks can be fitted with a porous HDPE IMS® Cap on top that helps to eliminate the need for support gravel (Figure 2). Figure 2. Sketch of typical underdrain design with dual channels (courtesy of Leopold, a Xylem brand)
Figure 3. Schematic diagram of substrate diffusion in a biofilm attached to a solid substratum Biological water and wastewater treatment processes are based on the growth of microbial communities capable of metabolizing contaminants through mediating oxidation-reduction reactions. The oxidants (electron acceptors) are normally oxygen, nitrate, perchlorate, sulfate, and Fe (III); the reductants (electron donors) are normally organic matter, trace organic compounds, ammonia, As (III), and iron (II) and Mn (Il), etc. In a fixed-film biological process, biofilms are developed on media such as sand, anthracite, granular activated carbon (GAC), or membranes. A biofilm process mainly consists of two simultaneous steps, substrate diffusion and biological reaction, as illustrated in Figure 3. Electron donors and acceptors diffuse from bulk fluid into the biofilm and are metabolized by microbial cells in the biofilm, as a result of which the diffusion profiles are parabolic. Electron donors and acceptors diffuse from bulk fluid into the biofilm and are metabolized
Figure 5. Phylogenetic tree of NOB based on a multiple alignment of 40 NOB 16S rDNA sequences. Abbreviations are Nb for Nitrobacter and Nsr for Nitrospira. Rh. capsulatus is in the Alphaproteobacteria class, R. eutropha is in the Betaproteobacteria class, and E. coli is in the Gammaproteobacteria class. Scale bar represents 10% sequence difference (Regan 2001)
Figure 1. Illustration of a series of spargered flotation cells where porous gas spargers are installed to inject-disperse air in the form of small gas bubbles (< 1.5 mm). It has been proposed and validated in laboratory, and pilot plant tests, the use of froth flotation to treat lead polluted water in a continuous scheme operation. In that case, lead is present in the aqueous phase as a lead colloidal carbonate, with a lead concentration of 20 ppm. A series of spargered flotation cells are used to perform the separation of the lead specie [5]; Figure 1 shows a representation of the series of flotation cells.
The polluted water presented a pH of 7.4, therefore a cationic collector was used to produce a hydrophobic behaviour to the lead carbonate particles. The series of flotation cells were operated until the steady state conditions were achieved. At this point an apparent residence time was estimated (t = [he:/Ji]x[1 — eg]; where he is the collection zone height measured from the bottom to the froth interface, Ji is the superficial liquid velocity, and eg is the gas hold-up); as a first approximation this representation of residence time may be used to express the nature of mixing in the series of flotation cells. o express the nature of mixing in the series of flotation cells. The different streams (concentrate, tailings, and feed) were sampled to analyse their concentration of lead, and to determine the recovery of this material through the separation process. The recovery of lead may be related to the characteristics of the process in terms of the variables ¢g, bubble size, the superficial bubble surface flux, and the kinetics of the process.
The lead reported to the concentrate shows that its recovery increases as the amount of gas in the gas-water dispersion rises, as a result of the increase in the availability of bubble surface area to perform the collection process of hydrophobic species. The flotation of the lead specie presents a steady increase with increasing until the gas hold-up reaches 7.7% (v/v) above which there is a sudden reduction on that operation variable due to the formation of excessive turbulence produced by a considerable flow of gas in the cell.
Figure 4. Effect of the bubble size on the separation of lead from the aqueous media.
Figure 5. Relationship between the separation of lead carbonate from the aqueous phase by flotation, and the superficial bubble surface flux. In terms of the bubble surface area, the concept of “superficial bubble surface flux,” Sb, has been suggested as a controlling ultimate flotation variable. Sb contains the chemical, hydrodynamics, and mechanical characteristics of the flotation system; Sb can be thought as the amount of bubble surfaces that flow through a unit of a cross sectional area normal to the bubbles motion, by unit of time, therefore with units of time”; therefore from geometry considerations, Sb = 6 (Jg/dv), where Jz is the superficial gas velocity, and db is the bubble diameter [11]. It has been demonstrated that Sb is directly related to the flotation - separation kinetics [12]. Figure 5 shows the relationship between the recovery of floated lead and Sb.
Figure 6. Behaviour of the apparent rate constant, as a function of the change on gas hold-up in the flotation of lead colloid carbonate. The apparent rate constant for the lead colloid carbonate flotation is presented in Figure 6 as a function of the gas hold-up in the collection zone. It is observed that the flotation rate constant follows a linear relationship with respect to the change in the gas hold-up if the last is kept below 8%. Above this gas hold-up value the correlation between the flotation kinetics and the gas hold-up changes. This information suggests that the lead colloid carbonate flotation rate is strongly dependent from the hydrodynamic conditions of the system.
It is observed in fig. 8 that the cumulative recovery of lead through the series of 5 flotation cells is 93% (w/w). The total residence time of water in the flotation circuit is 13 minutes. This water processing time gives the impression that is short, as compared with the reported processing times in laboratory flotation columns testing (between 30 to several hundreds of minutes) [2].
Figure 8. Cumulative recovery of floated lead as a function of the number of flotation cells series.
Figure 9. Representation of the laboratory flotation column assembly used to remove organics (oil, soap, solids) from water by froth flotation.
Figure 10. Organic recovery from water in the flotation column as the superficial gas velocity changes; the system is under different superficial liquid velocity. the organics recovery is plotted as a function of the superficial liquid velocity. relative velocities between the liquid flow rate and the gas flow rate. The performance in the flotation column is reported to increase circulation and mixing as the liquid and gas flow rates increase in the column, this in turns will increase the bubble coalescence producing a rise in the collection zone turbulences, consequently decreasing the collision possibility between the bubbles and the oily globules. Nevertheless, when the superficial liquid velocity is in a small value range (0.1 cm/s — 0.15 cm/s) the organics recovery has an increase with the increase in the liquid velocity, perhaps due to an increase of the retention of the air bubbles by the liquid flow in the collection zone. This effect can be noticed in fig. 11 where the organics recovery is plotted as a function of the superficial liquid velocity.
Figure 11. Organic recovery from water, reported in the flotation column concentrate, as a function of the superficial liquid velocity.
Figure 12. The effect of the superficial liquid velocity on the organic recovery/gas hold-up behaviour. It can be observed that the de-oiling process efficiency is high when the superficial liquid velocity is kept below 0.2 cm/s, but above that value there is a drastic decline on the separation efficiency, this behaviour is observed in whole range of superficial gas velocities reported here. Also, it is thought that as the superficial liquid velocity increases in the collection zone of the flotation column, the possibility that small gas bubbles charged with hydrophobic organic materials are gone with the tailings flow out of the column, and for this reason, decreasing the organics recovery. The experimental results plotted in fig. 12 suggest that large gas hold-up values are associated to small bubbles formation which will go down to the bottom of the flotation column because the effect of the downwards liquid stream; these experimental results support the impression that as the liquid flow rate increases the bubbles entrapment in the tailings stream also intensifies, producing low organic recoveries reported to the concentrate run. It can be noticed that under superficial liquid velocities above 0.15 cm/s the organic recovery in the concentrate ranges between 5% and 20%, which may be associated to large bubbles covered with the hydrophobic materials (which yields to such 5 to 20% organic recovery) and, therefore, most of the organic material collected by the gas bubbles is associated with the interactions with small bubble sizes. This idea is consistent with the hydrodynamic behaviour of gas bubbles moving in a liquid phase, since the oily globules present a lower density than the aqueous phase.
Figure 14. Behaviour of the organic recovery in concentrate with the change in the superficial bubble surface flux (Sb). The water de-oiling process in series stages of flotation columns. The water de-oiling process by column flotation was performed using a series of flotation stages. In this experience arrays of 2,3 and 4 flotation column sequence were operated. Figure 14 presents the column flotation results on the water de-oiling process in terms of the organic recovery — superficial bubble surface flux behaviour. Under the lower values of the superficial liquid velocity in the collection zone of the column, it is very clear that the hydrophobic organic flotation increases when the gas surface area which flows in the flotation column increases.
Figure 13. Effect of the bubble dimension on the recovery of organic floated.
Figure 15. Experimental set up of flotation column series. The experimental flotation columns array is schematically presented in fig. 15; this presentation shows that the residual water is fed into the first flotation column and the tailings from this column is used as the second column feed, and this arrangement is repeated up to four flotation columns.
Figure 16. Experimental results of water de-oiling in one flotation column and a series of 2, 3 and 4 flotation columns.
Figure 17. Transformation lines with changes on the metal concentration in the bulk solution. Pb —S—- 20 system.
Figure 18. Pourvaix diagram for the Cu-SOs-H20 system. A and B means the liquid and solid species that co-exist in a respective region. The Pourvaix diagram for the Cu — S — H20 system is shown in Figure 18, and Table 2: i shows the Gibbs free energy values for reactions (10), (11), and (12).
The corresponding thermodynamic values are shown in Table 3. Sean et al., [20], Chanturiya et. al., [21], Liu [22], Shigehito et. al., [23], and Guo-riu Fu [24], reported the precipitation of two nickel phases named a — nickel hydroxide, and 8 — nickel hydroxide, within the pH range established in this work. These species were detected by using both: XRD and IR analysis techniques. Figure 19. Pourbaix diagram for the Ni — SOs — H2O system. Changes on concentration of the ionic nickel are included.
Figure 20. XRD analysis for solids precipitated at pH 3. Experimental results for the case of lead, copper, and nickel salts simultaneously dissolved in distilled water. According to the experimental data and the thermodynamic calculations, each metal can be selectively precipitated and removed from the contaminated effluent. After each pH adjustment of the liquid, the solids were separated by centrifugation. The proposed procedure is as follows:
Table 3. Activity coefficient, Gibbs free energy, and equilibrium pH for reaction (13). 2.4. Selective precipitation of copper, nickel, and lead
Figure 22. XRD analysis for solids precipitated at pH 11. Experimental results for the case of lead, copper, and nickel salts simultaneously dissolved in distilled water.
Figure 21. XRD analysis for solids precipitated at pH 7.5. Experimental results for the case of lead, copper, and nickel salts simultaneously dissolved in distilled water.
Figure 24. Changes in the surface tension of the effluent with the time, due to the increment in the amount of lipids digested by the microorganisms. Even the pH of the media begins to be unsuitable for cell growth. At this time there are more dead than alive bacteria, then the scarcity of nutrient sources (sugars and lipids), the protein degradation process of the bacteria begins, and generates ammonia as degradation product. This process provides organic nitrogen sources as nutrient which transforms the system into alkaline, increasing the pH value [41].
Figure 25. Variations of the vegetable oil content in the industrial effluent treated by the microorganism Pseudomonas fluorescens. ‘he lipolytic activity of the microorganisms is presented in Figure 25. The initial oncentration of fat in the effluent was equal to 41.5 mg/l (taken as 100%); at 48 hours after nitiation of the experiment the oil content in the emulsion decreased to 34.2 mg/l (82.4%); at 6 hours of incubation, was reached a concentration below 10 mg/l (24%), and finally, aftex 44 hours of the vegetable oil content in the effluent was 4.6 mg/l (11%) and remained onstant from this point.
Figure 26. Biomass development (Pseudomonas fluorescens) during the degradation of an industrial Pe), errs The constant trend in the last two experimental points, shown in figure 3, coincides with the trends of both: pH and surface tension, shown in figures 1 and 2, respectively, which also agrees with the behavior of the biomass in the last two points of sampling, as can be seen in Figure 26.
The movement of groundwater depends on the permeability of the water bearing layers. Layers such as clay have a low permeability and tend to inhibit water flow, whereas sand or chalk layers have a high permeability and promote water flow. In the subsurface, low permeable layers will act as confining beds, while high permeable layers will be water bearing layers. A geological unit from which groundwater may be extracted is called an aquifer, and there may be distinguished between two types: unconfined and confined aquifers. A confined aquifer is a water bearing layer completely enclosed by confining layers. These aquifers will only slowly recharge, but are also well protected against anthropogenic pollution from the surface. An unconfined aquifer is in direct contact with the surface, and will as such rapidly recharge depending on the amount of rainfall, but will also be more exposed to activities on the surface.
Because of the natural filtration taking place during the formation of groundwater, usually only a simple treatment consisting of aeration and sand filtration is necessary to produce drinking water. In standard Danish drinking water production, the water is pumped to the waterworks, where it is aerated to remove dissolved gasses, and then led through a sand filter where solids are retained, before it is finally stored in a holding tank. Earlier, the treated water was stored in water towers or elevated containers, but this practice has been abandoned due to hygienic considerations. Instead, buried storage tanks and pumping systems are used today to create the necessary pressure in the water system. In Figure 2, addition of Ca(OH)z is also shown. The purpose of Ca(OH)2 is to remove aggressive COz, and may be necessary in areas with soft water. It is however not a part of the standard simple treatment, but belongs to the category of extended treatment techniques, which is covered after the simple treatment. As a final general remark, it should be noted that one of the unique features in the Danish drinking water treatment process is the missing disinfection step. No chlorine or other disinfectants are added to the water at any time during the drinking water process, resulting in high quality water. Figure 2. General process diagram for a Danish waterworks. The addition of Ca(OH), is not part of the standard simple treatment. Reprinted with permission from Esbjerg Water Supply (Forsyningen Esbjerg).
Figure 3. Pourbaix diagram for iron, showing the most thermodynamical stable form as a function of pH and redox potential.
Figure 4. Reaction scheme for the oxidation of manganese in sand filters, where Me symbolizes a transition metal ion.
Figure 6. Concentration levels of major constituents of groundwater through Spangsbjerg Waterworks simple drinking water treatment. As seen, iron and manganese are effectively removed by the sand filters. Manganese are not affected significantly by the pure oxidation, but is almost completely removed already in the first filter. Some iron is removed by the homogenous oxidation, and needs to go through both filters to be reduced to below the accepted threshold limit. Ammonium is not directly measured, but the graph shows that the ammonium in the water is effectively converted to nitrate in the first filtration step. This is important since it shows that the conversion is complete in the first sand filter, meaning that no nitrite is left in the treated drinking water. Calcium and magnesium passed unaffected through the waterworks together with other macro ions as K*, Na*, Cl, SO? and the main part of HCOs . The unchanged hardness is also to be expected since Spangsbjerg Waterworks only applies aeration and sand filtration, which do not affect the solubility of calcium and magnesium minerals significantly.
Figure 7. Map of drinking water wells in which arsenic has been found in the period from 1981 to 2006 Modified from Viden om Grundvand (15). removal of arsenic (12). In Figure 7, it can be seen where in Denmark arsenic has been found in the drinking water, and it is clear that the clay rich eastern part of Denmark from east Jutland and eastward is the most affected. Arsenic is often bound to iron minerals and released when ferrihydrite (Fe(OH)s3) is reduced or pyrit (FeS) is oxidized. However, it has been found that by applying reduced iron, arsenic can be made to co-precipitate (13). At Galten waterworks near Aarhus, the concentration of arsenic was found to be 21 ug/L, and experiments with addition of FeSOs were made at the smaller waterworks Galten Vestermarks. The method has been found to be effective. Based on these results, in 2004 Galten waterworks applied for permission to use FeSOs, in concentrations of 5 mg/L, for removal of arsenic, to be able to meet the threshold limit. The permission was given, but only for a two year period based on the recommendation of the health inspector (11). In 2008 Galten waterworks got permission to use FeClz to remove arsenic (14). Galten waterworks got permission to use FeCl2 to remove arsenic (14).
Figure 8. Map of groundwater wells (1993-2004) and drinking water wells (1993-2010) where pesticides have been found (1,15). Modified from Viden om Grundvand (15). One of the biggest issues in the Danish drinking water sector is contamination of the groundwater with pesticides, and it is estimated that between 1993 and 2009 around 130 wells all over the country have been closed due to pesticide pollution (16). Since 1993 the degree of pesticide pollution of the Danish groundwater has been monitored by the Danish geological service (GEUS), and during the years, an ever increasing amount of the aquifers has been found to be contaminated, as seen in Figure 9. This is not so much a result of an increasing actual pollution, as it is a result of more and more pesticides being included into the monitoring program. In the latest report, it was found that between 1990 and 2010, 50.7 % of the monitored aquifers had been polluted with pesticides, and that 24.5 % of the wells used by the water works contained pesticides (1). In Figure 8 it can be seen that all parts of Denmark, bot rural and cities, are affected by the pollution. However, the monitoring program does only cover parts of the aquifers in Denmark, and the pesticides currently in the monitoring program only constitute 29 % of the total sale of pesticides in Denmark from 1988 to 2010. The degree of pesticide pollution may as such be expected to increase over the coming years, forcing more waterworks to initiate extended treatment.
Figure 9. Development in the percentage of the Danish groundwater reserve where pesticides have been found from 1990 to 2010 (1).
This process introduced air or oxygen into a mixture of primary treated or screened wastewater combined with organisms to develop a biological floc which reduces the organic content of the sewage, which is largely composed of microorganisms such as saprotrophic bacteria, nitrobacteria and denitrifying bacteria. With this biological floc, we could degrade
The MBR has a higher organic pollutant and ammonia removal efficiency in comparison with the activated sludge process. Besides, the MBR processes is capable to treat waste water with higher mixed liquor suspended solids (MLSS) concentrations compared to activated sludge process, thus reducing the reactor volume to achieve the same loading rate. However, membrane fouling greatly affects the performance of this technique, since fouling leads to significantly increase trans-membrane pressure, which increased the hydraulic resistance time as well as the energy requirement of this reactor. Alternatively frequent membrane cleaning and replacement is therefore necessary, but it significantly increases the operating cost.
Figure 3. The scheme of upflow anaerobic sludge blanket reactor [1]
The advantages of this system are as follow: 1) the filler provides a large surface area for th growth of the microorganisms, and the filler also increases hydraulic retention time of th wastewater; 2) the system provides a large surface area for the interaction between th wastewater and film; 3) the fact that microorganisms grow on the filler reduces the run of th degraders. These advantages could increase the efficiency of this treatment, and guarantee th water quality of the effluent. The backward of this system is that the system could be blocke when dealing with high concentration organic water, especially in the water inlet parts. An no simple and effective way for filter washing has been developed yet.
on the filler of the constructed wetland, plants can supply carbon and other nutrients suct as nitrogen through their roots to for the growth and reproduction of the microorganisms Plants could also pump oxygen to form an aerobic and anaerobic area in the deep level o: constructed wetland to assist the breaking down of organic materials. The major reactor ir constructed wetland was supposed to be microorganisms, and microorganisms and natura chemical processes are responsible for approximately 90 percent of pollutant removal while, the plants remove about 7-10 percent of pollutants. In addition to organic pollutants this device could remove the nitrogen and phosphorous in the wastewater and preven eutrophication. Figure 6. The scheme of the subsurface flow constructed wetland of different feeding pattern
Figure 5. The scheme of the oxidation ditch [1]
Introduction of hydrogen peroxide into the waste stream is critical due to lower stability of hydrogen peroxide. An addition point should give large residence time of H2O2 in the pollutant stream, but due to the practical constraints and poor mixing conditions, it is not always possible to inject H2O2 in line and an additional holding tank is required. The simplest, faster and cheapest method for injection of hydrogen peroxide is gravity feed system. Pump feed systems can also be used, but it requires regular attention. Figure 7 reports a simplified flow diagram of the WHPCO technology for the treatment ot olive oil milling waste water using Fe-ZSM-5 solid catalysts. H2O2 is added progressively at the top of a fixed bed catalytic reactor (before a static mixer), in order to maximize its loca! concentration. An iron solution is added on the top of the reactor to maintain catalyst activity constant. The feed solution is recirculated to and from a tank in order to have good turbulence in the catalyst bed, but also to guarantee the necessary total residence time tc obtain the required level of removal of phytotoxic chemicals.
resistant material, because the Fenton reagent is very aggressive and corrosion can be a serious problem. pH of the solution must be adjusted at 6, usually iron hydroxide is formed. For many organic pollutants, the ideal pH for the Fenton reaction is between 3 and 4, and the optimum catalyst to peroxide ratio is usually 1:5 wt/wt. Addition of reactants are done in the following sequence: dilute sulfuric acid catalyst in acidic solutions, pH adjusting agent (adjustment of pH at 3-4) and lastly added hydrogen peroxide slowly. Effluent of the Fenton reactor (Oxidation tank) is fed into a neutralizing tank for adjusting the pH (adjustment of pH at 9), then the stream followed by a flocculation tank and a solid-liquid separation tank for removing the precipitate. A schematic representation of the Fenton oxidation treatment has been shown in Figure 8 [21]. 3.1.2.3. Typical reactor used for ozonation Ozone transfer efficiency should be maximized by increasing the interfacial area of contact (reducing the bubble size by using small size ozone diffusers such as porous disks, porous glass diffusers, ceramic membranes) and increasing the contact time between the gas and the water (increase the depths in the contactor, optimum being 3.7 to 5.5 m) [21].
Figure 9 reports a simplified flow diagram of a WACO process which consists mainly of a high-pressure pump, an air or oxygen compressor, a heat-exchanger, a high-pressure (fixed bed) reactor and a downstream separator. The simplest reactor design is usually a cocurrent vertical bubble column with a height-todiameter ratio in the range of 5-20. A catalytic unit for the treatment of the off-gas is also typically necessary [25].
Figure 1. Cyclic voltammograms recorded with a potential scan rate 0.05 Vs! between 1.25 and -0.5V vs. SCE in a 0.1M Na2SOs supporting electrolyte (curve 1) and in the presence of 25 mg-L*! 4-CP (curve 2) at a) EG-Epoxy, b) EG-CNF-Epoxy, c) AgZEG. d) EG-PS; e) GC; f) BDD electrode.
Figure 2. Cyclic voltammograms of a) EG-Epoxy and b) AgZEG in the presence of different 4-CP concentrations: 1-0 mM; 2-12.5 mgL"; 3-25 mgL*; 4-37.5 mgL*; 5-50 mgL-1; 6-62.5 mgL"* in a) 0.1 M Na2SOs supporting electrolyte; potential scan rate 0.05 Vs". Inset: the calibration plots of the current densities vs. 4-CP concentration. as reference for electrooxidation applying under galvanostatic regime (constant current). Thus, depending on the applied current density (iapp!), two different operating regimes have been identified [43,47] i.e., iappi<itim the electrolysis is under current control with the current efficiency of 100% and iappi > iim the electrolysis is under mass-transport control and the secondary reactions of oxygen evolution are involved with a decreasing of current efficiency. However, the choice of iapp) must consider the process or electrochemical efficiency, which is limited by the electrode fouling and also, the electrical charge consumption.
Figure 3. Cyclic voltammograms recorded at BDD electrode in: (a) 1M Na2SO: supporting electrolyte under dark (1) and UV irradiation (2); and (b) in the presence of 50 mgL! 4-AP under dark (1’) and UV irradiation (2’) at the potential scan rate of 0.1 Vs".
Chronoamperometric results have been used to determine the serie of electroactivities for 4- CP oxidation at the tested electrodes. For a more electroactive material having a diffusion coefficient D, the current corresponding to electrochemical reaction is described by the Cottrell equation [48]:
Table 5. Electrochemical reaction rate constant of 4-CP at the carbon-based electrodes In general, the dependence of the electrochemical reaction rates on the concentration of organic pollutants has been described by a pseudo first-order equation based on the relation In (Co/Ci)=kapp(t). Also, the apparent rate constant was calculated based on the relation of In(Co/C:)=k’ app(C), in which C represents the electrical charge passed during electrochemical oxidation of 4-CP. The kinetic results were obtained by monitoring changes in 4-CP concentration as a function of the reaction time. Based on the results gathered in Table 4 can be concluded that 4-CP oxidation process occurred with a fast kinetics on carbon composite electrode. However, in terms of charge consumption, the BDD electrode exhibited the best apparent rate constant, an expected result takes into account that no oxygen evolution occurred at the potential value applied on this electrode and lower electrical charge was involved.
Figure 6. 4-AP removal efficiency (a) and electrochemical efficiency (b) by electrooxidation process using BDD electrode in 1 M NazSOs and in the 64 mg:L* 4-AP; the applied techniques are: curve 1- CA, curve 2— MPA. Multiple-pulsed amperometry (MPA) is a technique appropriate for in-situ electrochemical leaning of an electrode during the oxidation process. The effect of MPA applying is presented here in comparison with optimized CA technique for the electrochemical yxidation of 4-AP using boron-doped diamond (BDD) electrode. The operating conditions or MPA, a cleaning potential of +1.75 V and an oxidation potential value of +1.25 V vs. \2¢/AgCl were selected, taking into account that the oxidation potential is similar to that of “A and that the cleaning potential should be higher but very close the oxygen evolution »otential.
Figure 5. 4-AP removal efficiency (a) and electrochemical efficiency (b) by electrooxidation process using BDD electrode in 1 M NazSOs and in the 64 mg-L" 4-AP; the applied techniques are: curve 1 — E=0.5 V vs Ag/AgCl, curve 2 — E=0.9 V vs Ag/AgCl, curve 3 — E=1.25 V vs Ag/AgCl, curve 4— E=1.75 V vs Ag/AgCl.
Figure 7. Evolution of removal efficiency of 4-AP determined by spectrophotomertry (solid) and TOC (open) by electrooxidation at the current density of 10 mA cm (™) and 5 mA cm?(e).
Figure 8. Evolution of removal electrochemical efficiency of 4-AP determined by spectrophotometry (solid) and TOC (open) by electrooxidation at the current density of 10 mAcm (™) and 5 mA cm2(e).
Figure 9. Evolution of the mineralization current efficiency (solid) and the specific energy consumption (open) with the electrolysis time in the electrochemical oxidation of 4-AP in 0.1 M Na2SOs supporting electrolyte at the current densities of 10 mA cm? (curve 1) and 5 mA cm? ( curve 2).
Figure 10. UV spectra profiles of 4-AP after degradation by photocatalysis (2), electrooxidation (3), photocatalytically-assisted electrooxidation (4), in comparison with initial 4-AP (1). 120 minutes, about 16, 36 and 72 % of TOC was removed by the application of photocatalysis, electrochemical oxidation and_ respective, photocatalysis-assisted electrooxidation. The lower values of TOC removal degrees compared with 4-AP removal ones supported the fact that for all applied oxidation processes the complete mineralization of 4-AP to CO2 was occurred via intermediaries as carboxylic acids.
Figure 11. Evolution of 4-AP degradation with the reaction time, expressed as: a) 4-APt/a-APo and b) TOC:/TOCo; (™)photocatalysis; (W )electrooxidation; (&)photocatalytically-assisted electrooxidation. Decontamination of Wastewaters Containing Organics by Electrochemical Methods 305
Figure 12. Evolution of the mineralization current efficiency (solid) and the specific energy consumption (open) with the electrolysis time in the electrochemical oxidation of 4-AP in 0.1 M Na2SO4 electrolyte for the application of: 1-electrooxidation; 2- photocatalytically-assisted electrooxidation. ‘igure 12. Evolution of the mineralization current efficiency (solid) and the specific energy Decontamination of Wastewaters Containing Organics by Electrochemical Methods 307
Figure 13. Cyclic voltammograms of EG-Epoxy in 0.5 M Na2SOs supporting electrolyte (1) and in the presence of 25 mgL! 4-CP concentrations: before (2) and after (3) chronoamperometry applying at +1.1 V vs. Ag/AgCl for 2 h.
spindle poisoning which induces an anomalous disjunction of chromosome at anaphase, has usually been considered a genotoxic indicator. On the other hand, chemicals substances can induce micronuclei promoting changes in the achromatic fuse (aneugenic effect). Micronuclei arise when the lost genetic material is involved by a nuclear envelope, independent of nuclear envelope of the principal nucleus [48]. When the interphase cell is exposed to environmental pollutants, damage is produced either in whole chromosomes - in G1, or damage in individual chromatids - S and G2 phases. Anomalies typically found in S phase are gaps and chromatid breaks [49]. Moreover, during mitosis, all types of AC may be found. Chromosome breaks, bridges and lagging chromosomes may result from sticks and are considered to induce aneuploid and polyploid cells. The stick form can be related to the depolymerization of DNA, the dissolution of nuclear proteins or with an increase in chromosome condensation. Figure 2. Mitotic anomalies and micronucleus observed in root meristematic cells of Allium cepa exposed to water samples of the Paraiba do Sul river - Brazil: a. chromosome bridges; b. not identified; c. multipolar anaphase; d. c-mitose; e. stickiness; f. micronuclei [47].
Figure 3. Allium cepa bioassay: a 20 L bucket was used for collecting the samples and transferred to 40 I containers (up); bulbs were exposed to treatment for 24 hours; growth root and root stained with Schiff (down). studies to evaluate the potential damage inflicted by pollutants in aquatic environments. Furthermore, even one bulb and one root per bulb was sufficient in discerning this damage, thereby shortening the time required to attain a statistically confident comparative evaluation. However, to allow for the use of statistical programs based on the evaluation of average values, and to avoid criticism based on genetic variability, we propose that three bulbs and three roots per bulb be considered as standard sample sizes for the A. cepa test [46].
Figure 4. Indication of the cities (Tremembé and Aparecida) ‘triangles’ at which the water was sampled from the Paraiba do Sul river [19]. The Paraiba do Sul river (Figure 4) is one of the components of the Paraiba do Sul basin, of importance to the southeast region of Brazil, as it serves for urban supply, irrigation, generation of energy, and assimilation of urban, industrial and agricultural discharges in the mentioned region. For this reason, since 2005, samples of water of this important river, collected in cities along its course, have been periodically evaluated. Anatomo-morphologic parameters (root growth), mitotic indices (MI), cell division phase indices (PI), frequency of micronuclei (MN) and chromosome anomalies (CA) are investigated.
Plate 1. 1.Stephanodiscus hantzschii Grunow 2.Cyclotella comta (Ehrenberg) Ktitzing 3.Thalassiosira weissflogii (Grunow) G.Fryxel & Hasle 4.Aulacoseira distans (Ehrenberg) Simonsen 5.Cyclotella ocellata Pantocsek 6. C. kiitzingiana Thwaites 7.Cocconeis pediculus Ehrenberg 8.C.placentula Ehrenberg 9. Meridion circulare (Greville) C. Agardh 10. Diatoma vulgaris var. lineare Grunow 11. D. tenuis C.Agardh 12. Surirella ovalis Brébisson 13. S. ovata var. apiculata W. Smith 14. S. linearis W. Smith 15. S. minuta Brébisson 16. Cymatopleura solea (Brébisson) W. Smith [14].
organically polluted waters [13]. Some diatom taxa in a stream polluted with the waste water of a slaugher house are given in Plate 1-4 [14]. Plate 2. 1. Pinnularia viridis (Nitzsch) Ehrenberg 2. P. biceps W. Gregory 3. Stauroneis phoenicenteron (Nitzsch) Ehrenberg 4. Pinnularia brebissonii (Kitzing) Rabenhorst 5. Craticula ambigua (Ehrenberg) D. G. Mann 6. Pinnularia mesolepta (Ehrenberg) W. Smith [14].
Plate 3. 1. Rhopalodia gibba (Ehrenberg) Otto Miller 2-3. Eucocconeis flexella (Kiitzing) Meister 4. Achnanthidium minutisimum (Kiitzing) Czarnecki 5. Eucocconeis quadratarea (Ostrup) Lange-Bertalot 6. Achnanthes marginulata Grunow 7. Ulnaria delicatissima var. angustissima (Grunow) M. Aboal & P. C. Silva 8. U. acus (Kiitzing) M. Aboal 9. U. amphirhyncus (Ehrenberg) Compere & Bukhtiyarova 10. U. danica (Kiitzing) Compere & Bukhtiyarova 11. U. biceps (Kiitzing) P. Compere [14].
Plate 4. 1.Fragilaria capucina var. vaucheriae (Kiitzing) Lange-Bertalot 2.Pseudostaurosira brevistrita (Grunow) D.M.Williams & Round 3.Staurosirella pinnata (Ehrenberg) D.M.Williams & Round 4.Gomphonema truncatum Ehrenberg 5.Rhoicosphenia abbreviata (C. Agardh) Lange-Bertalot 6.Gomphonema olivaceum (Hornemann) Brébisson 7.Nitzschia sublinearis Hustedt 8.N. umbonata (Ehrenberg) Lange- Bertalot 9. N. hantzschiana Rabenhorst 10. Tryblionella angustata W. Smith 11. Nitzschia linearis (C. Agardh) W. Smith12. N. constricta (Kiitzing) Ralfs. [14].
Figure 1. Removal efficiency of organic nitrogen in treatment methods [44]. 1-nitrification, 2-oxidation pond, 3-chemical coagulation, 4-chlorination, 5-ammonia removal, 6-filtration, 7-reverse osmosis
The total pond area needed is much larger than that needed for a conventional plant, but ponds should still cost only one-third to one-half as much to build. Another important advantage of the plant is the small amount of sludge they produced. For example, during nearly 3 decades of operation, St. Helena’s wastewater treatment plant has never had to remove residue and measured less than 1 meter of residue had accumulated at the bottom of the deep digester pit [59]. Figure 2. Food web in facultative wastewater treatment pond [51]
Figure 3. Flow Scheme of the Accelerated Photosynthetic Process for Waste-Water Treatment and Algal Protein Production [56]
Figure 1. Sectors in Palic Lake (red circle - target place for restoration) This lake is separated into 4 sectors (Fig. 1). Sector 2, which covers the area of 81 ha, has been made to improve the quality of inflowing water from wastewater treatment plant. Sector 4, the biggest part of the lake, is designed for recreational purposes. It coveres around 372 ha and the initial depth of lake was 2 m. Nowdays, some parts of the lake are covered with thick sediment layer, causing variations in lake's depth. Central section for wastewater treatment of Subotica town lies in the depression of the far west end of Palic Lake. Water from this treatment unit inflows into the lake. Wastewater treatment plant (WWTP) of the city of Subotica was built in 1977, and since than the capacity of the plant was enlarged (in 1983). In 1997 it has been revealed that the amount of influent was 80% higher than the planned one. This exessive wastewater has predominantly originating from precipitation that clogged and blocked the operation of treatment facility unit. In the period of extremely high precipitation, the excess water was transported into lagoons and further on, as untreated water, into the lake. In 1985 the capacity of treatment unit was enlarged, but due to numerous omissions, the so called “treated” wastewaters have been discharged into the lake. The analyzed data show that the lake was loaded with more than 4t of total phosphorus in August 1970.
The capacity of new WWTP is 36.000m°, while during rainy days it gets enlarged up to 72.000m°. The new treatment facility has shown to be very efficient in achieving good effluent quality regarding all the analyzed parameters. The amount of discharged water from new WWTP into the lake is bigger, but its quality is undoutably better (Figure 2). This will certainly influence the processes in the lake.
Figure 3. Total phosphorus concentration trends in sectors of Palic lake (mg/l) during period from 1978 — 2010
Figure 5. BOD (mg/l) trends in sectors of Palic lake during period 1978 - 2010
Figure 4. Total nitrogen concentration (mg/l) trends in sectors of Palic lake during period 1978 - 2010
Figure 6. The concentration of As and Ni in Palic Lake (sector 2) compared to Holland and Canadian i
In this manner total area of constructed wetland will have a part in water treatment, which is joint work of all zones, as depicted in Figure 7. All processes that are important for achievement of recommended water quality are increased. Some modifications that encompass introduction of biofilters and floating wetland were also done, to increase efficiency of constructed wetland. Figure 7. Scheme of the sequential model of wetland in sector 2 (longitudinal section)
We should also bear in mind that decomposition of macrophytes in wetland may also release large amounts of nutrients [40], and thus could reduce wetland treatment efficiency [41]. Plant decomposition plays an important role in nutrient cycling in aquatic ecosystems [43-43]. Harvesting is considered a direct and effective way to solve the re-pollution The design of constructed wetland (Figure 8) depends on many factors but the plant species and microbial populations directly affect the efficiency in water treatment. Starting from the quality and quantity, especially treated water coming from the WWTP into the lake, and in order to obtain the required water quality for the sector 4 we proposed a model of constructed wetland that will maximize the potential of plants and microorganisms.
Table 1. Differences between conventional and emerging forms of water Governance (based on Tropp, 2007) A public-private governance mechanism in water sector involves transferring asset management or operations of a public water system into private sectors. Several public- private arrangements are service contracts, management contracts, leases, concessions and build-own-transfer programs. In this governance system, ownership of water systems can be distributed between public and private shareholders in a corporate utility. Majority ownership is usually kept within the public sector. In service contract, a private company is responsible for a specific task, such as meter installation, distribution pipe maintenance or collection of bills. Under management contracts, government transfers certain operation and maintenance activities to a private company. Under the concession and Build Operate Transfer (BOT) models, capital investment, commercial risk, operations and management of the project are undertaken by the private sector. Concessions are usually long-term to allow the private company to recover its investments. At the end of the contract, assets are either transferred back to the public sector or another concession is granted. In the BOT model, the role of government is predominately regulatory. BOT models are usually used for water and wastewater treatment plants. management or operations of a public water system into private sectors. Several public-
(MBTU is million British thermal unit)
Some Details of Mathematical Modelling of Effluents in Rivers Downstream of aWWTP 41
Table 2. Modelling BOD concentrations at a downstream distance of 200 m at a temperature 20°C. show its merits with different treatment efficiencies. We are interested about biological oxygen demand (BOD) in this case. We assume the calibrated and validated value of transverse mixing coefficient constant is equal to 0.408. Secondly we assume calibrated and validated value of the temperature dependent first order rate coefficient for BOD equal to 2.31.10 s at a temperature 20°C. The CIT model computes concentration of BOD at point of interest using Equation (5). Resulting concentration of BOD at a downstream distance 200m can be found in Table 2.
CLI - clinoptilolite; STI — stilbite; PHI — philipsite; HEU — heulandite *LOI - Loss of ignition
This confirms the theoretical study of the suitable position of Na* ions in zeolite structure and possibilities of zeolite exchange with metal ions from solutions. Na-modifications have shown the highest selectivity for zinc ions when Zn?* ions are mixed together with Fe* ions, which is highly dependent on the acidity of the solution and cation hydratation enthalpy. Chemical modification of zeolite with FeCls solutions is defined by the parameter system: 0H“ solution, ionic strength of the solution, oxidation-reduction conditions, iron concentration and the type of salts used (chlorides, sulphates, nitrates, perchlorates, etc.). Fe?* and Fe* ratio results in sorption of iron ions and iron oxi-hydroxides on the surface and n the pores of clinoptilolite. However, regardless of the portion of different iron forms oresent in zeolite structure, the common property of all iron modified zeolites is a high ncrease in sorption capacity for arsenic oxi-anions present in water solutions. According to iterature data, two mechanisms of arsenic binding on the surface of iron oxi- hydroxide are: the mechanism of surface precipitation and the mechanism of surface complexation. Surface complexation mechanism can be monodentate, dominant at a low surface coverage of nodified zeolite, or bidendate at higher surface coverage when iron forms complexes with arsenic [42-44].
Table 5. Cation-exchange capacities of different zeolitic materials (*CEC is operationally defined — determine the amount of a cation that can be removed by a specific substance once the material and solution have come to equal) [16].
where Kr and n are Freundlich constants determined from the slope and intercept of plotting Inge vs. InCe. Table 6. Other important isotherms models are used to describe the equilibrium sorption distribution.
The Freundlich isotherm: where qe is metal concentration on the zeolite at equilibrium (mg of metal ion/g of zeolite); Qmax (mg/g) and Ki (1/mg) are Langmuir constants related to the maximum adsorption capacity corresponding to complete coverage of available adsorption sites and a measure of adsorption energy (equilibrium adsorption constant) respectively. These constants are found from the slope and intercept of ce/qe vs. ce linear plot so that Qmax = 1/slope and Ki = slope/intercept.
Table 7. Gibbs free energy of sorption (AG°) different metal ions.
* Membrane processes: Ultrafiltration, Nanofiltration, Reverse osmosis CLI - clinoptilolite; M-CLI modified clinoptilolite; CHA — chabazite; SCO — scolecite; PHI - philipsite obtained concentrate metal ions after regeneration of the zeolite, very positively impact or the environment without creating new waste. Table 8 shows the efficiency of the removal o: metal cations from wastewater using natural zeolite which is supplemented with othe: physical and chemical methods. The efficiency of removing metal ions from wastewater: depends on many factors such as initial concentration of metal ions in wastewater, the pF value of the system, the possibility of formation of metal hydroxyl anion, previous chemica and thermal modification of zeolite and the amount of water that should be purified Besides the already mentioned properties (selectivity, capacity, etc.) natural zeolites have excellent resistance to chemical, biological, mechanical or thermal changes.
For efficient water treatment an important property of natural zeolite is regeneration through cyclic processes and their re-use. Recent studies of desorption efficiency of metal ions and regeneration natural zeolite - clinoptilolite are presented in Table 10 and indicate that the process is reversible in most cases [77]. Sorption of ions on to iron modified natural zeolite depends on the success of chemical modification and creation of iron hydroxide on its surface. Effect of solution pH and initial concentration of arsenic ions in water are very important for removal efficiency of arsenic ions [7, 44]. The sorption efficiency of arsenic ions on to iron modified zeolite (Serbia) decreases in the order: Pb (II)> As (V)> Mn (II)> As (III) = Cr (VI) (Figure 10 (left). With increasing initial concentration of As (V) ions removal efficiency of As (V) ions decreases continuously with the use of natural zeolites from deposit D.Jesenje (Croatia) and V. Banja (Serbia). Also, at higher initial concentration of arsenic ions (300 mg/L) removal efficiency of
Table 9. Effect of chemical pretreatment on the removal efficiency of cations by natural zeolite - clinoptilolite.
Table 11. The removal efficiency of cations in column process (*QB - breakthrough capacity)
Table 3. Percentage removal efficiency of turbidity, color, Giardia e Cryptosporidium and pH values after coagulation/flocullation process with moringa. Using moringa as coagulant, turbidity ramoval was in the range of 3 — 97,4%. The lower removal efficiencies were in the range of 3-45,6% for water with low initial turbidity (50 NTU), removal below 90% were observed for water with turbidity 250, 350 e 450 NTU. The
Table 2. Water sample parameters before treatment processes.
Table 1. Characteristics of different media used for water filtration
Phosphorus supplementation in a pilot study decreased biofilter terminal headloss by ~15 percent relative to the control likely the result of reduced EPS formation in the filter, and decreased contaminant breakthrough relative to the control biofilter, including MIB (~75 percent less breakthrough), manganese (~90 percent less breakthrough), and DOC (~15 percent less breakthrough) (Lauderdale et al. 2011).
Table 2. Design parameters and findings for the removal of natural organic matter removal (NOM) in WeotwiaAiie efiidioe
Unlike the removal of TOC, placing ozonation in front of GAC filters was not benefiting the removal of MIB and Geosmin likely due to the competition from increased AOC (Vik et al. 1988). An important design parameter is EBCT, which is usually in the range of 5-20 minutes depending on the required removal. GAC filters provided resistance to temperature variation while the removal was reduced by 24% for both Geosmin and MIB when temperature was reduced from 20 to 8°C in anthracite filters (Elhadi et al. 2006). At lower temperatures (6-12 °C), MIB and Geosmin removal was also reduced with expanded clay by 15% and 10%, respectively, compared to that at 15 °C (Persson et al. 2007). Biodegradation of both MIB and Geosmin was determined to be a pseudo-first-order reaction, with rates influenced by the initial amount of the biofilm biomass (Ho et al. 2007). As a result, sand with a well-established biofilm taken from a 26 years old filter was capable of removing MIB and Geosmin to below detection limits after 11 days of operation while sand without an established biofilm removed 60% Geosmin and 40% MIB after 154 days of operation (McDowall et al. 2007). Four bacteria, a Pseudomonas sp., an Alphaproteobacterium, a Sphingomonas sp. and an Acidobacteriaceae member were identified as microorganisms most likely involved in the biodegradation of Geosmin within the sand filters (Ho et al. 2007).
Table 3. Design parameters and findings for the removal of MIB and Geosmin in previous studies Conventional Media Filtration with Biological Activities 147
5-7. Arsenite tends to adsorb less strongly than arsenate. Source water containing arsenite generally requires using a strong oxidant, e.g., chlorine, chlorine dioxide, and ozone, to oxidize arsenite to arsenate which can be removed by coagulation and filtration. Arsenic (V) removal by either ferric chloride or alum was relatively insensitive to variations in source water composition below pH 8 meanwhile arsenic (III) removal by ferric chloride was less efficient and more strongly influenced by source water composition than arsenic(V) removal (Hering et al. 1997). The presence of sulfate (at pH 4 and 5) and natural organic matter (at pH 4 through 9) adversely affected the efficiency of arsenic (IIT) removal by ferric chloride and arsenic(III) could not even be removed by coagulation with alum (Hering et al. 1997). Table 4. Design parameters and findings for the removal of iron and manganese in previous studies
Table 5. Design parameters and findings for the removal of arsenic in previous studies
Table 6. Design parameters and findings for the removal of ammonia in previous studies 1.12 without acclimation and 1.06 with acclimation (Andersson et al. 2001). At temperature less than 4 °C, nitrification seemed un-sustained and feeding low temperature culture (psychrophiles) seemed necessary (Andersson et al. 2001). However, in fixed-film biofilters, the impact of temperature on nitrification rate was less significant than that predicted by the van’t Hoff-Arrhenius equation, and a temperature increment at 20 °C resulted in a nitrification rate increase of 1.108% per degree and 4.275% per degree under DO and ammonia limiting conditions, respectively (Zhu and Chen 2002).
Table 7. Design parameters and findings for the removal of nitrate and perchlorate in previous studies
Table 4. Residual oil in the synthetic emulsion after microbial action. With the appropriate conditions for the growth of the bacteria colony (pH, temperature, dissolved oxygen, surface tension, and nutrients), it was possible to quantify the lipolytic capacity of the microorganisms: Candida Kefir, Candida Parapsilosis, Pseudomonas Fluorescens, Bacillus Cereus, and Bacillus Coagulans, individually and in bulk. Since the purpose of this stage of the work was to establish the lipolytic character of the above mentioned microorganisms, the measurements of residual oil in water were carried out at the beginning and at the end of the experimental digestion. The experimental results are shown in Table 4. the experimental digestion. The experimental results are shown in Table 4.
Table 5. Development of biomass in the degradation of a synthetic emulsion.
Treating of Waste Water Applying Bubble Flotation 191
Table 8. Experimental conditions for de-oiling of an industrial effluent using a laboratory biological reactar A set of experiments were run by using a transparent acrylic plexiglass cell as biological reactor (30 cm by side and 40 cm in height), with 4 taps properly located to adjust 4 sensors for measuring continuously: pH, temperature, dissolved oxygen, and surface tension of the system. A bubble generator (made of filter cloth) was installed at the bottom of the reactor. The air feed to the cell was measured and controlled through a mass flow controller. The system was operated under stationary regimen, and open to the atmosphere. Table 4.5 shows the experimental variables applied in this particular research. shows the experimental variables applied in this particular research.
Table 7. Characteristics of an effluent from an edible vegetable oils factory. A sample of the effluent from an edible vegetable oils factory was collected. The amount of oil, quantified according the Soxhlet technique [40], was of 41.45 mg/l, which is above the naximum permissible value for the environmental standards. The initial pH of the sample was 5.6 and this value does not affect the growth of the Pseudomonas fluorescens bacteria, since this microorganism is naturally acidophilus. Table 7 shows the measured variables to he original sample.
Table 1. Division of groundwater constituents into component groups. iia ane: aia The most important factors affecting the composition of groundwater is the composition o the water after the immediate infiltration of the top layers of the surface, the geology of thi subsurface, and the flow rate of the water through the subsurface. As the water move through the subsurface, it is constantly approaching equilibrium with the surroundins geological layers. The type of equilibrium reactions are determined by the initia composition of the water and the specific geology of the subsurface, which therefor becomes very important for the final composition of the groundwater. The flow rate of th water controls the time available for the water to reach equilibrium with the surroundings which is important since the equilibrium reactions vary in rate of reaction. In the upper par of the subsurface, the composition of the water is mainly determined by pH and redo conditions, and because of differences in rate of reaction, specific zones and fronts will bi formed. These fronts and zones are general, and will be found in most places. At deepe levels, the retention time for the water is greatly increased, and slower reactions becom: influential. Here the specific geological conditions determine the composition of th groundwater, and this may result in very different types of groundwater. The type o groundwater is defined based on a division of its constituents into a number of groups a seen in Table 1. To understand the presence of these constituents, a more detailec description of the before mentioned processes is necessary.
*The conversion from meq/L depends on the molar mass, and the calcium concentration in the last column has been calculated by assuming that only calcium is present. High concentrations of dissolved calcium carbonate can also be an issue. When groundwater is exposed to the atmosphere or is heated, CO2 will diffuse out of the solution, which then becomes supersaturated with calcium carbonate. Groundwater’s content of calcium carbonate is commonly given in units of hardness, which is actually a measure of the content of Ca* and Mg” ions in the water. Magnesium is included since it is often found along with calcium minerals and has similar characteristics. Hardness is divided into three types: Total, transient and permanent. The total hardness is the total sum of Ca** and Mg** ions. The transient hardness is the amount of Ca?* and Mg** ions dissolved as a result of COz. Table 2. Hardness classification as a function of total hardness (2).
* The concentration of oxygen at the tap must be 5 mg/L, and the waterworks therefore strive to saturate the water with oxygen, which will often result in a concentration around 10 mg/L after the waterworks.
Table 4. Oxygen demand for main oxidizable components in groundwater (5). Groundwater Chemistry and Treatment: Application to Danish Waterworks 233 Sand filtration
In Table 6 an overview of the techniques applied as extended treatment in the Danish drinking water sector is given. It is seen that for some of the problems only one type of technique has been investigated, as with the use of active carbon filtration for removal of pesticides, whereas for other problems, a wider range of techniques have been applied. The use of different techniques is also correlated to the number of times the problem has been encountered.
Table 1. The load, cost accounting and effluent of different treatments Sewage is one of the most important sources of degradable organic pollutants, whicl contributes to 37.5% of total COD in China in 2011. Therefore, sewages are treated befor discharge in order to reduce the impact of the pollutants to the environment. Severa biological methods, including aerobic biodegradation, activated sludge reactor, membrans bioreactor, constructed wetland etc., have been used in the sewages treatment, and thei efficiency and cost have been compared. Taking the research of Song as an example!®l, ir response to the characteristics of decentralized domestic sewage, several treatmen technologies including biogas purification tank, constructed wetland, viewing earthworn ecological, high rate algal pond, membrane bioreactor and integrated treatment equipmen were applied to the domestic sewage, and their efficiency and cost were calculated anx showed in table 1.
Table 2. The load, cost accounting of oxidation pond and sequencing batch reactor (flocculation) and biological methods (aerobic biodegradation, activated sludge reactor, sequencing batch reactor, oxidation pond) could be used to remove the pollutants. Most of the physical and chemical techniques are costly and need secondary treatment, therefore, food wastewater was mainly treated by biological methods. The cost varied greatly with the characters of the influent. Longda food industry compared the load and cost of oxidation pond and sequencing batch reactor, results were shown in the table 2 [64]. pond and sequencing batch reactor, results were shown in the table 2 [64].
Table 1. Electrical resistance of the carbon composite electrodes The carbon-based composite electrodes were characterized morphologically by scanning electron microscopy and a homogeneous distribution of carbon filler within the insulating matrix was found [30-32]. The electrical resistance of each electrode was measured by a four- point resistance method [34] and the results are gathered in Table 1.
Table 2. Voltammetric parameters for 25 mgL7 4-CP oxidation on carbon based electrodes. Decontamination of Wastewaters Containing Organics by Electrochemical Methods 295
Table 4. Process efficiency (ncr) and electrochemical efficiency (Ecr) for 4-CP degradation by chronoamperometry Decontamination of Wastewaters Containing Organics by Electrochemical Methods 299
Table 6. The pseudo-first order kinetic apparent constant for the degradation of 4-AP determined by spectrophotometry and TOC analysis
Table 9. Calculation of biomass yield and assimilated quantities of nutrients by emerged plants [39]. Water column is in contact with active layer of sediment, whose thickness varies from a millimetre to few centimetres. If anaerobic conditions prevail in superficial sediment layer, phosphorous becomes mobile in pore water of active layer that is assumed to be 2 cm. Examined phosphorous loading is derived using concentrations of total phosphorous, thus calculated values represent sediment potential. Output is a sum of phosphorous that is consumed by plants in vegetated zones of designed wetland and plants in floating wetlands; while one portion is represented as autopurification capacity (Table 10). Here, a portion that is affiliated by submerged plants and free floating vegetation is neglected, due to the fact that it is hard to control this kind of vegetation and predict their effects reliably.
Table 7. The apparent rate constant for the degradation of 4-AP determined by spectrophotometry and TOC analysis function of electrical charge For the electrochemical and combined processes, the apparent rate constant determined by spectrophotometry and TOC analysis was calculated based on the relation of In(Co/Cr)=k’ app(C), in which C represents the electrical charge passed during electrochemical! and combined oxidation of 4-AP. The results are gathered in Table 7, and it can be noticed that the apparent rate constants determined for 4-AP concentration and TOC measurements for photocatalysis-assisted electrooxidation process are the best. Also, the effective mineralization rate was assessed as the ratio between the apparent rate constant calculated for TOC analysis and the apparent rate constant calculated for spectrophotometry analysis (k’app,toc/k’ app4-ar). The value of this ratio closer to 1 indicated that the effective mineralization rate was achieved. The value of 0.88 compared with 0.82 for electrooxidatior confirmed the enhancement effect of photocatalysis application on the electrooxidatior process of 4-AP using BDD electrode to reach the mineralization.
Table 2. Comparison of wastetreatment ponds in terms of various criteria
This area is characterized by continental climate, with a severe winters, hot summers and irregular distribution of precipitation. The average air temperatures are 10.8°C (Table 1), air humidity is 69% and air pressure is 1007mb. Annual number of rainy days is 105 and the average perennial mean precipitation values are 561.1mm, while the number of days with snow cover is 59 per year. This area is also characterized by strong winds (wind speed more than 6 Bf, i.e. 34 km/h), during 104 days per year [20].
Eutrophication: Status, Trends and Restoration Strategies for Palic Lake 357
In sampling period the water was covered with foam which indicates presence the surface active materials in water. This is due to Serbia still used anionic detergent with phosphate which than caused acceleration eutriphication in shallow water. The content of total organi: carbon (TOC) is high which indicates the intensive organic output. High concentration o chloride and sulfate are consequence of theirs high content in treated waters from WWTP The concentration of ammonium ions are moderate high, but nitrite nitrogen had extremely high. Five day (BODs) was 2.2 (Table 3) and is due presence of easily biodegradable organi material the, but in sector 4 the sums was 8 [24].
* location of open water zones are given in figure 1 The deeper parts of the sediment layer have higher concentrations of heavy metals as a result of historical pollution of the lake. The concentration of As and Ni exceed the defined Holland [28] and Canadian [29] limits, as well as the concentration of Cr which is also higher than the recommended limits, while Cu concentration is just a bit above the maximum threshold (Figure 6). Table 4. Chemical and microbiological analysis of sediment in sector 2
Fecal coliforms and fecal streptococcus haven’t been detected in the water (Table 4). It should be noted that in some sectors had detected the presence of fecal coliforms [24]. Periodially in the tourist part of the lake, due to the presence of pathogenic bacteria and reduced quality of water it is necessary to prohibit swimming. Continously monitoring the
Basic parameters for design and sizing of future wetland are water quality that is discharged in the lake and requested lake water quality. Since the new wastewater treatment plant started, effluent quality improved significantly, although it still represents nutrient burden for the lake (Table 6).
Table 8. Basic ecophysiological traits of proposed plants for future constructed wetland In studied case, selected plants fulfil following conditions: they are tolerant to high nutrient content and they live in continuous aquatic conditions, i.e. plants that periodically need dry conditions are avoided. Furthermore, it is best to use perennial plants, as well as plants with bigger rate of biomass increase. Plants that have slower growth rate should be grown with bigger density. The best practice is to grow many different plant species, especially the ones that represent important habitat to animals. Monoculture should be avoided, because it can lead to quicker spread of diseases and be attacked by insects. According to data given from other authors [34], the Indigenous plants that are appropriate for future wetland creation in sector 2 of the Palic Lake are chosen together with basic ecophysiological traits and given in table 8.
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UTILIZATION OF RECYCLED AND WASTE MATERIALS IN VARIOUS CONSTRUCTION APPLICATIONS
by Sen Huei-Lynn
More production equals more waste, more waste creates environmental concerns of toxic threat. An economical viable solution to this problem should include utilization of waste materials for new products which in turn minimize the heavy... more
Most commonly recycled material used in concrete Fig. 2. Most commonly used recycled material in concrete
Fig. 1. Most commonly used recycled materials for construction applications Johnny Bolden et al. / American Journal of Environmental Science 9 (1): 14-24, 2013
Most commonly used recycled material in asphalt paving Fig. 3. Most commonly used recycled material in asphalt paving
Fig. 5. Awareness of Recycled materials for construction applications Recycled materials that companies are aware of
Fig. 4. Reasons of not using recycled materials Johnny Bolden et al. / American Journal of Environmental Science 9 (1): 14-24, 2013
Fig. 7. Why companies are using recycled materials
Fig. 6. The percent of materials that need more data Johnny Bolden et al. / American Journal of Environmental Science 9 (1): 14-24, 2013
Table 1. Selected recycled materials and their construction applications 2.14. Animal Fat in the production of concrete. Results of several studies have indicated the benefits of using sewage slag ash in concrete such as compressive strength, freeze- thaw resistance and good hardening properties. Sewage sludge ash may be used as a mineral filler substitute or as a portion of the fine aggregate in hot mix asphalt paving.
Findings show that 14% of the companies are completely unaware of other recycled materials being used in construction. This suggests the need for education and awareness programs to introduce the availability and applicability of the recycled materials. Figure 5 shows the percentage of materials the companies are aware of in the construction industry
Table 4. Reasons of not using recycled materials As aforementioned, 65 participants from 50 different construction related companies participated in this study. 4.1, Statistical Analysis
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Standard methods for the examination of water and wastewater
by Chalbi Marie Fernandez

1912

Y ellowstone National Park Water Quality Monitoring Greater Y ellowstone Inventory and Monitoring Network
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General Chemistry 9th-Ebbing.Gammon
by jorge rafael reyes fajardo
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BIOTECHNOLOGY FOR WASTE AND WASTEWATER TREATMENT
by Adel Mageed and 
1 more
Pubul Martín
Various conventional methods that are used in biological treatment are listed in Table 1 along with the treatment agents and typical wastes that are treated.
Figure 3. Variations of the activated sludge process. Biotechnology for Industrial and Municipal Wastes S$
UNIT PROCESS
During the biological denitrification, bacteria reduces nitrite or nitrate to nitrogen gas. The heterotropic bacteria require a source of carbon. In denitrification reactions, this supplemental source is often provided by methanol. The nitrogen reaction is a respiratory process encompassing the following reactions. The nitrogen cycle is complex like all biogeological cycles. Its essential components are:
Testing for Recalcitrance
Figure 3. Reprinted from: TCE Degradation by a Methane-Oxidizing Bacterium. Little et al., App & Env Mic, April 1988.
Biological Degradation of Hazardous Wastes 7:
Figure 6. Proposed relationship between benzene and the PAHs used in the study.
Figure 7. Chemical transition structure. Reprinted from Mahaffey et al., App & Env Mic, Oct 1988.
Biotechnology for Waste and Wastewater Treatment
Figure 10. Possible mechanism of defluorination of 3-fluoro substituted benzenes by Pseudomonas sp, strain T-12 involving toluene-2,3-dioxygenase. Reprinted from Renganathan, App & Env Mic, vol. 55 #2, Feb. ’89, p. 332.
Figure 11. Proposed initial steps of alph-HCH degradation under aerobic conditions in a slurry of contaminated soil. (A) Alpha~-HCH; (B) PCHH; (C) 1,2,3,5-TeCB; (D) 1,2,4-TCB; (E) 1,2,4-DCB; (F) 1,2-DCB; (G) 1,4-DCB. Reprinted from Bachman et al., App & Env Mic, vol. 54, Feb. ’88, p. 553.
aniline and other organic substrates by strain K1 has significance for the degradation of aniline in natural environments. If other substrates such as glycerol or lactate are present, this strain can continue to degrade aniline, and if the aniline is present only in small concentrations, the microbial population can still be supported which can then transform the xenobiotic at a high rate.
Biotechnology for Waste and Wastewater Treatment
Figure 2. Various post aeration devices.
Figure 5. Improved sludge processing for an activated sludge plant.
Biological Treatment of Industrial Wastes: Mutant Bacteria 13:
Figure 7. Landfill gas production during the biological degradation process. Biological Treatment of Industrial Wastes: Mutant Bacteria 133
Nitrification and Denitrification in the Activated Sludge Process
8 Biotechnology for Waste and Wastewater Treatment
Nitrification and Denitrification in the Activated Sludge Process 1
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Solar Tracking, Sun Tracking, Sun Tracker, Solar Tracker, Follow Sun, Sun Position
by Gerro Prinsloo and 
1 more
Robert Dobson
Free to download eBook on Practical Solar Tracking Design, following the sun solar tracking system, sun tracking system, sun tracker system, solar tracker system, sun positioning system, and sun path tracking with follow the sun position... more
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