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E NVIRONMENTAL S CIENCE , E NGINEERING AND T ECHNOLOGY S ERIES F LUID W ASTE D ISPOSAL
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Nitrous Oxide Emissions Conservation of Natural Resources Research Progress
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in Plant-Based Products
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Fluid Waste Disposal
Potential of Activated Kay W. Canton (Editor)
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Sludge Utilization
Xiaoyi Yang 2010. ISBN: 978-1-60876-019-0
E NVIRONMENTAL S CIENCE , E NGINEERING AND T ECHNOLOGY S ERIES F LUID W ASTE D ISPOSAL K AY W. C ANTON E DITOR
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L IBRARY OF C ONGRESS C ATALOGING - IN -P UBLICATION D ATA
Fluid waste disposal / editor, Kay W. Canton. p. cm. Includes index.
ISBN 978-1-61122-590-7 (eBook)
1. Sewage disposal. I. Canton, Kay W. TD741.F55 2009 628.3--dc22
Published by Nova Science Publishers, Inc. New York
C ONTENTS
Preface
ix
Chapter 1
Treatment of Wastewater by Electrocoagulation Method and the Effect of Low Cost Supporting Electrolytes
Lazare Etiégni, K. Senelwa, B. K. Balozi, K. Ofosu-Asiedu,
A. Yitambé, D. O. Oricho and B. O. Orori
Chapter 2
Application of Sulphate-Reducing Bacteria in Biological Treatment Wastewaters
49 Dorota Wolicka
Chapter 3
Utilization of Water and Wastewater Sludge for Production of Lightweight-Stabilized Ceramsite
83 Zou Jinlong, Yu Xiujuan, Dai Ying and Xu Guoren
Chapter 4
Modelling and Observation of Produced Formation Water (PFW) at Sea
D. Cianelli, L. Manfra, E. Zambianchi,
C. Maggi and A. M. Cicero
Chapter 5
Disposal of Sulfur Dioxide Generated in Industries Using Eco-Friendly Biotechnological Process – A Review
A. Gangagni Rao and P.N. Sarma
Chapter 6
Novel Biological Nitrogen-Removal Processes: Applications and Perspectives
J.L. Campos, J.R. Vázquez-Padín, M. Figueroa,
C. Fajardo, A. Mosquera-Corral and R. Méndez
Chapter 7
Application of Microbial Melanoidin-Decomposing Activity (MDA) for Treatment of Molasses Wastewater
Suntud Sirianuntapiboon and Sadahiro Ohmomo
Chapter 8
Wastewaters from Olive Oil Industry: Characterization and Treatment
Usability of Boron Doped Diamond Electrodes in the Field of Waste Water Treatment and Tap Water Disinfection
Hannes Menapace, Stefan Weiß, Markus Fellerer, Martin Treschnitzer and Josef Adam
Chapter 10
Utilization of Biosolids as Fertilization Agents on Agricultural Land: Do the Obvious Benefits of Recycling Organic Matter and Nutrients Outweigh the Potential Risks?
237 Veronica Arthurson
Chapter 11
Integrated Approach for Domestic Wastewater Treatment in Decentralized Sectors
249 Rani Devi and R. P. Dahiya
Chapter 12
Biodegradation Characteristics of Wastewaters
265 Fatos Germirli Babuna and Derin Orhon
Chapter 13
Batch Treatment of a Coffee Factory Effluent for Colour Removal Using a Combination of Electro-Coagulation and Different Supporting Electrolytes
L. Etiégni, D. O. Oricho, K. Senelwa B. O. Orori,
B. K. Balozi, K. Ofosu-Asiedu and A. Yitambé
Chapter 14
Water as a Scarce Resource: Potential for Future Conflicts
297 M. A. Babu
Chapter 15
Recycling Wastewater After Hemodialysis: An Environmental and Cost Benefits Analysis for Alternative Water Sources in Arid Regions
307 Faissal Tarrass, Meryem Benjelloun and Omar Benjelloun
Chapter 16
Pb (II) Ions Removal by Dried Rhizopus Oligosporus Biomass Produced from Food Processing Wastewater
H. Duygu Ozsoy and J. Hans van Leeuwen
Chapter 17
Control of Plasticizers in Drinking Water, Effluents and Surface Waters
Rosa Mosteo, Judith Sarasa, M. Peña Ormad and Jose Luis Ovelleiro
Index
P REFACE
Wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations. In the most common usage, it refers to the municipal wastewater that contains a broad spectrum of contaminants resulting from the mixing of wastewaters from different sources. With the dwindling available water resources in the world coupled with high population growth, pressure is being exerted on water and wastewater plant managers the world over to find cost-effective methods to treat a wide range of wastewater pollutants in a diverse range of situations. This new and important book gathers the latest research from around the globe on fluid waste disposal with a focus on such topics as: wastewaters from the olive industry, application of sulphate-reducing bacteria in biological treatment wastewaters, electrocoagulation treatment method, usability of boron doped diamond electrodes in wastewater treatment and others.
Chapter 1 - Coagulation and flocculation are traditional methods of treating of polluted water. Electrocoagulation (EC) presents a robust novel and innovative alternative in which a sacrificial metal anode doses water electrochemically. This has the major advantage of providing active cations required for coagulation, without necessarily increasing the salinity of the water. Electrocoagulation is a complex process with a multitude of mechanisms operating synergistically to remove pollutants from water. A wide variety of opinions exist in the literature for key mechanisms and reactor configurations. A lack of a systematic approach has resulted in a myriad of designs for electrocoagulation reactors without due consideration of the complexity of the system. A systematic, holistic approach is required to understand electrocoagulation and its controlling parameters (pH, temperature, conductivity, current density). This will enable a priori prediction of the treatment of various pollutant types. Electrocoagulation involves applying a current across electrodes in water. This results in the dissolution of the anode (either aluminum or iron). These ions then form hydroxides which complex with and/or absorb contaminants and precipitate out. The precipitate with the contaminants can then be removed from the water by settling and decantation or filtration. EC has the potential to be applied in many other areas besides the textile and semiconductor industry. It has been successfully tested in the pulp and paper industry, as well as tea and coffee processing. However over electrical potential within electrodes during
Kay W. Canton
the electrocoagulation process uneconomical. The inclusion of supporting electrolyte such as NaCl achieves this. One of the methods pioneered by researchers at Moi University in Kenya is the use of wood ash leachate as supporting electrolyte which in some cases could reduce energy consumption by as much as 80%. Other supporting electrolytes tested are ash from bagasse and from coffee husks. These supporting electrolytes are relatively inexpensive, but they all generally result in large amount of coagulated sludge. Other supporting electrolytes such phosphate rock are less effective than wood ash, but they yield almost 50% less sludge after electrocoagulation. Most of the supporting electrolytes have an added advantage of reducing other wastewater pollution parameters such as BOD, COD, TSS, TS, turbidity, pH and color. Because of the inherent benefits of these low cost supporting electrolytes, electro- chemical methods could be a credible alternative to more traditional wastewater treatment approaches.
Chapter 3 - Disposal of wastewater treatment sludge (WWTS) and drinking-water treatment sludge (DWTS) is one of the most important environmental issues nowadays. Traditional options for WWTS and DWTS management, such as landfilling, incineration, etc., are no longer acceptable because they can cause many environmental problems. Conversion of WWTS and DWTS into useful resources or materials is of great interest and must be intensely investigated. To attain this goal, WWTS and DWTS were used as
components for making ceramsite. Part I: SiO 2 and Al 2 O 3 were the major acidic oxides in WWTS and DWTS, so their effect on characteristics of ceramsite was investigated. Results show that WWTS and DWTS can be utilized as resources for producing ceramsite with
optimal contents of SiO 2 and Al 2 O 3 ranging from 14 –26% and 22.5–45%, respectively.
Bloating and crystallization in ceramsite above 900 ℃ are caused by the oxidation and volatilization of inorganic substances. Higher strength ceramsite with less Na-Ca feldspars
and amorphous silica and more densified surfaces can be obtained at 18%≤Al 2 O 3 ≤26% and γ0%≤SiO 2 ≤45%. Part II: Fe 2 O 3 and CaO were the major basic oxides, so their effect on characteristics of ceramsite was also investigated. The optimal contents of Fe 2 O 3 and CaO are
in the range of 5% –8% and 2.75%–7%, respectively. Higher strength ceramsite with more complex crystalline phases and fewer pores can be obtained at 6% ≤Fe 2 O 3 ≤8%. Lower strength ceramsite with more pores and amorphous phases can be obtained at 5% ≤CaO≤7%, which implies that excessive Ca 2+ exceeds the needed ions for producing electrical neutrality of silicate networks. Part III: To investigate stabilization of heavy metals in ceramsite, leaching tests were conducted to find out the effect of sintering temperature, pH, and oxidative condition. Results show that sintering exhibits good binding capacity for Cd, Cr, Cu, and Pb and leaching contents of heavy metals will not change above 1000 ℃ . Main compounds of heavy metals are crocoite, chrome oxide, cadmium silicate, and copper oxide, which prove that stronger chemical bonds are formed between these heavy metals and the components. Leaching contents of heavy metals decrease as pH increases and increase as
H 2 O 2 concentration increases. Leaching results indicate that even subjected to rigorous leaching conditions, the crystalline structures still exhibit good chemically binding capacity for heavy metals and it is environmentally safe to use ceramsite in civil and construction fields. It is concluded from the 3 parts that utilization of WWTS and DWTS can produce high performance ceramsite, in accordance with the concept of sustainable development.
Chapter 4 - Through the last decades, the ever increasing energetic demands have been Chapter 4 - Through the last decades, the ever increasing energetic demands have been
Preface
‗formation water‘, that lies underneath the hydrocarbon layer, and ‗additional water‘ usually injected into the reservoirs to help force the oil to the surface. Both formation and injected waters, named ―produced formation waters‖ (PF→s), are separated from the hydrocarbons
onboard offshore platforms and then disposed into the marine environment through ocean diffusers. PFWs contain several contaminants and represent one of the main sources of marine environment pollution associated with oil and gas production.
This makes the study of PFW fate of paramount importance for a proper management of environmental resources as well as for planning and optimizing the discharge and monitoring procedures.
In the first part of this chapter we provide a detailed description of the chemical characteristics of PFWs and their potential toxic effects and review the mixing processes governing their dispersion in the marine environment. In the second part of the work we briefly review past efforts in observing and modelling PFW spreading in the ocean. Finally, we propose a multidisciplinary approach, integrating in situ observations and numerical modelling, to assess dispersion of PFWs in space and time. As a case study we will refer to the results of a previous study conducted in the Northern Adriatic Sea, a sub-basin of the
Mediterranean Sea, where a number of offshore natural gas (CH 4 ) extraction platforms are currently active. Chapter 5 - Sulfur dioxide (SO 2 ) is a known pollutant and responsible for various ill effects on living and non-living organisms. SO 2 emissions can be reduced by using non- conventional energy sources or using conventional fuels containing less sulfur. However, under the present circumstances SO 2 emissions cannot be completely avoided due to the reasons of rapid industrialization. Various technologies are available for the removal of SO 2 from flue and waste gases. Most of these technologies fall under the category of physical, chemical or thermal. All these technologies generate secondary pollutants ending up in disposal problems and also cost prohibitive. Biotechnology offers relatively cheaper solutions for the conventional problems. Due to this reason, biotechnology is making in roads into the conventional treatment processes in all the fields. Over the last decade, efforts have been made to develop biotechnological alternatives to conventional physico- chemical processes
for the removal of SO 2 from flue gases known as Biological flue gas desulphurization (BIO- FGD).SO 2 from flue gas can be absorbed in a suitable organic media. In the aqueous phase SO 2 would be converted to sulfite and some part may again be converted to sulfate due to the presence of dissolved oxygen. Therefore, the aqueous phase will be having both sulfate and sulfite, which can be reduced to sulfide using Sulfate Reducing Bacteria (SRB) under anaerobic conditions. The sulfide formed in the anaerobic reactor could be converted to elemental sulfur using Sulfur Oxidizing Bacteria (SOB) under partial microbial aerobic conditions. The elemental sulfur can be used either as a soil conditioner or raw material for industrial applications. Therefore, BIO-FGD process could be an environmentally benign and
economically viable alternative for the disposal of SO 2 emitted from the industries especially from power plants and refineries. The present article reviews the state of art of BIO-FGD process.
Chapter 6 - Since the requirement for nutrient removal is becoming increasingly stringent, a high efficiency of nitrogen removal is necessary to achieve a low total nitrogen Chapter 6 - Since the requirement for nutrient removal is becoming increasingly stringent, a high efficiency of nitrogen removal is necessary to achieve a low total nitrogen
Kay W. Canton
not suitable to treat wastewater with a low COD/N ratio because it involves the addition of an external organic carbon source and, therefore, an increase of the operational costs.
Several alternative processes for nitrogen removal can be applied in order to reduce partially (―nitrite route‖) or totally (anammox, autotrophic denitrification) the organic matter required. Such processes suppose not only an economical way to treat these wastewaters but
they are also more environmentally friendly technologies (lower production of CO 2 ,N 2 O and sludge; lower energy consumption). Up to now, they were basically applied to the return sludge line of municipal wastewater treatment plants (WWTPs). However, these processes could even be implemented in the actual WWTPs in order to achieve more compact and energy efficient systems.
Their potential advantages can make them also feasible technologies to treat polluted ground water or to remove nitrogen compounds from recirculating aquaculture systems. Chapter 7 - This review will discuss the melanoidin-decomposing activity (MDA) among microorganisms. The focus will be on the potential use of the microbial-MDA to treat the wastewater discharged from factories using molasses as the raw material (molasses wastewater: MWW) because molasses is one of the most useful raw materials in various types of industries, such as the fermentation and animal feed industries. However, the wastewater discharged from factories using molasses contains a large amount of dark brown pigment, melanoidin pigment: MP, which is poorly decomposed and/or decolorized by normal biological treatment processes, such as the activated sludge or anaerobic treatment systems (anaerobic pond or anaerobic contact digester), because, the microorganisms in those wastewater treatment systems showed very poor MDA. The distribution of MDA among microorganisms and the mechanism of decomposing activities, in particular, were reviewed. Also, the application of the isolated strains having the MDA to treat molasses wastewater in the wastewater treatment plant was tested.
Chapter 8 - Countries in the Mediterranean basin are among the main producers of olive oil. The elaboration of olive-oil is typically carried out by small companies in small facilities. The olive-oil plants produce high and variable amounts of residual waters of olives and olive- oil washing (OMW) that has a great impact in the environment. According to the procedure used different types of OMW with different chemical oxygen demand can be generated, the
OMW from the three phase process (COD = 150 g O L -1 2 ) and the OMW from olives washing (COD = 0.8-4.5 g O L -1 ) and olive oil washing (COD = 1.1- 6 g O L -1 2 2 ) in the two-phase process. The uncontrolled disposal of OMW is a serious environmental problem, due to its high organic load, and because of its high content of microbial growth-inhibiting compounds, such as phenolic compounds. The improper disposal of OMW to the environment or to domestic wastewater treatment plants is prohibited due to its toxicity to microorganisms, and also because of its potential threat to surface and groundwater. These waters normally are stored in great rafts of accumulation for their evaporation during the summer. This solution among others until the moment dose not represent a definitive solution for this problem, especially as the administrations more and more demanding the preparation of this spill and the constructive quality of the rafts. Today, effective technologies have been proposed such as
the chemical oxidation process using ferric chloride catalyst for the activation of H 2 O 2 as a treatment of OMW produced from two-phase process. In the previous works the authors have described the experimental results on laboratory-scale. These results have been taken to pilot- the chemical oxidation process using ferric chloride catalyst for the activation of H 2 O 2 as a treatment of OMW produced from two-phase process. In the previous works the authors have described the experimental results on laboratory-scale. These results have been taken to pilot-
Preface
next to 370 mg L -1 (%COD removal = 86.2%), and the water obtained can be destined to irrigation or disposed directly to the municipal wastewater system for their tertiary treatment. OMW from three-phase process does not allow direct chemical and biological purification for
its content in phenolic compounds and generally used natural and forced evaporation process. Another way of using is the application of OMW nutrients to the growth of microorganisms such as microalgae.
Chapter 9 - Over the past few years one main focus on the research efforts at the Institute for Sustainable Waste Management and Technology (IAE) has been on possible applications for reactors with boron doped diamond electrodes (BDD) in the field of (waste) water treatment. This article deals with the technical construction of the electrodes used (continuous reactor with a different number of plate electrodes), which were produced by a spin-off of the institute. The electrodes consist of conductible industrial diamond particles (< 250 µm), which are mechanically implanted on a fluoride plastic substrate. These electrodes showed a high mechanical and chemical stability in different test runs. At the institute, treatment methods for micro pollutants (e.g. pharmaceuticals and complexing agents) were developed with electrochemical oxidation by BDD. In this case test runs were made on laboratory scale and technical scale treatment units and elimination rates up to 99 % were achieved. In this
project the analytic is partly provided by the ―Umweltbundesamt GmbH‖ (UBA), one of the project partners. This agency has been a project partner in different studies about pharmaceuticals in the ecosystem. These techniques could also be used for the waste water treatment of alpine cabins. Pilot projects have been set up. On the basis of these results a
follow-up project was launched last October, in which an alternative treatment process for oil- in-water emulsions and mixtures was developed by the usage of electrochemical oxidation with BDD. A third possible application is the disinfection of drinking water from contaminated ground and spring water. In this process oxidation agents like ozone or OH radicals produced in situ by the BDD reactor from the treated water are used to eliminate bacterial contaminants (for example e. coli) in the water.
Chapter 10 - Treatment of wastewater, commonly performed at municipal sewage plants, generates sanitized water and sewage sludge. Anaerobic degradation of sewage sludge results in the production of different gases, including the economically valuable methane, and digested residue (biosolids) with potential value as a crop fertilizer. Traditionally, digested sewage sludge is disposed either into water, onto or into the earth or into the air. However, alternative exploitation of digested sewage sludge in agriculture has several advantages over commercial fertilizers, including environmental aspects benefiting agricultural sustainability and increased crop yield. Additionally, residue utilization is nearly always a cheaper option than disposal costs.
Biosolids obtained from the treatment of municipal sewage sludge consist of a mixture of organic and mineral compounds that significantly affect soil microbial communities and their biogeochemical activities when applied as a crop fertilizer. The microorganisms influence soil quality through nutrient cycling, decomposition of organic matter and maintenance of soil structure, in turn, affecting agricultural and environmental quality, and subsequently, plant and animal health. Moreover, both soil and residue normally contain considerable quantities of microorganisms, including both beneficial and potentially human pathogenic species that Biosolids obtained from the treatment of municipal sewage sludge consist of a mixture of organic and mineral compounds that significantly affect soil microbial communities and their biogeochemical activities when applied as a crop fertilizer. The microorganisms influence soil quality through nutrient cycling, decomposition of organic matter and maintenance of soil structure, in turn, affecting agricultural and environmental quality, and subsequently, plant and animal health. Moreover, both soil and residue normally contain considerable quantities of microorganisms, including both beneficial and potentially human pathogenic species that
Kay W. Canton
present a modified microbial community composition after some time and, hence, a modified ecosystem function.
At the end of the present chapter, we discuss whether the potential risks of recycling biosolids to agricultural cropland are acceptable for consumers, producers and scientific expertise, in view of the resulting alterations in soil microbial diversity, activity and accompanying functions. Furthermore, optimal ways of managing the recycling process to achieve the most favourable balance of benefits and risks for the community are highlighted.
Chapter 11 - The purpose of the present study was to design an integrated wastewater treatment system for a nalla (riverlet) flowing through Indian Institute of Technology Delhi (IITD), India, besides its cost estimation and comparison with the conventional wastewater treatment system. The design parameters for integrated aeration-cum-adsorption tank were
worked out for 240 m 3 / d flow rate of the wastewater. The important parameters used for the design included initial COD and BOD concentration in the influent, treatment time, adsorbent
dose, pH, adsorbent particle size and the desired COD and BOD in the effluent after treatment as prescribed by Central Pollution Control Board, (CPCB) Delhi, India. All the design parameters of this system were similar to those of conventional system except for the replacement of aeration tank in conventional system by the aeration-cum-adsorption tank. The concentration of COD and BOD of the treated effluent by the integrated system were well within the permissible limits of CPCB standards (for COD it is 100 ppm and for BOD of 30 ppm) to discharge in the canal for irrigation purpose. It was worth mentioning here that the adsorbents used in the present study were based on discarded materials which were available free of cost. Of course, the cost of their transportation and processing should have been taken into account.
The total cost estimated for the conventional system and the adsorption based system would be Rs. 198,312 and Rs. 141,275 respectively (including civil work, machinery, labour, adsorbent and miscellaneous). The cost difference for the two systems would be approximately Rs 57,037.
This design of integrated system has resulted into saving of cost by 28 % over the conventional system. Thus, it is a good approach for saving of conventional energy in addition to saving the cost of treatment and can be applicable for any country for decen- tralized sector. Moreover, it is an open ended research and we can recommend more research by changing the adsorbents types and operating parameters to improve the model.
Chapter 12 - The objective of this chapter is to put forward an overview of biodegradation characteristics of wastewaters by emphasizing the significance of COD fractionation. Recalcitrant COD fractions of effluents can be used as a tool to evaluate whether discharge standards can be met with a prescribed biological treatment. Moreover, the appropriate type of biological treatment applicable to the wastewater under investigation can
be addressed and the performance of an existing biological treatment system can be appraised with reference to inert COD fractions. Besides recalcitrant COD fractions of segregated industrial effluent streams can be regarded as an essential input of a sound industrial wastewater management strategy adopting minimization at source philosophy. Last but not least, data on COD fractions can be used as a solid source of information for modelling studies that define the design and performance of biological treatment systems. In this context, COD fractionation data on a wide spectrum of activities ranging from various be addressed and the performance of an existing biological treatment system can be appraised with reference to inert COD fractions. Besides recalcitrant COD fractions of segregated industrial effluent streams can be regarded as an essential input of a sound industrial wastewater management strategy adopting minimization at source philosophy. Last but not least, data on COD fractions can be used as a solid source of information for modelling studies that define the design and performance of biological treatment systems. In this context, COD fractionation data on a wide spectrum of activities ranging from various
Preface
biodegradation characteristics. Chapter 13 - In the present study, two types of colour removal systems were tested on effluent samples collected from a coffee pulping factory which discharged on average 15 m 3 of wastewater daily with a colour index of about 2500 O
H that was too high for direct discharge into a river in Kenya. The two colour removal systems used were: (i) electrolysis combined with wood ash or coffee husks leachate and (ii) electrolysis combined with phosphate rock solutions at a rate of 0.5 g/l to 4g/l. Phosphate rock is often used as
2 agricultural liming agent. The surface area of the electrodes was set at close to 75 m 3 /m of effluent with a current density of 1,200 mA/m 2 . The experiments were laid out in a stratified
random sampling design and the data were analysed using the Statistical Package for Social Scientists (SPSS) computer programme version 10.0. Electrolysis combined with phosphate rock (ELPHOS) proved to be the best process in terms of power consumption (68% reduction) compared with the 57% reduction by electrolysis combined with wood ash (ELCAS) and the 58% reduction by electrolysis combined with coffee husks ash (ELCHAS). Besides the 100% colour removal, ELPHOS also reduced other effluent physico-chemical parameters such as BOD, COD, TSS and TS by 79%, 80%, 69%, and 88% respectively. The analysis of ELPHOS treated wastewater showed that the mill could discharge an effluent that meets local discharge standards for colour requirements. It is recommended that recycling of the treated water by ELPHOS back to the factory for cleaning and washing purposes be considered since the quality meets the requirement for uses of fresh water for cleaning purposes. Furthermore, calculation of power consumption based on a scale-up batch reactor
of 15 m 3 proved less expensive to treat the factory effluent than a set of 12 one 100-L reactors similar to the one used in the field.
Chapter 14 - The major aim of this paper is to review the major problems of water resources in the developing countries. It is based on problems related to population growth and pollution and how these are more likely to lead to future conflicts. We know that fresh water is only 3 % of the total global water and 78% of this is in glaciers. This makes it a scarce and precious resource which must be sustainably managed. The paper also analyses some of the already existing and potential conflicts based on water resources. It reviews the potential threats to Ugandan water resources and problems which are most likely to occur as a result of these threats. Factors hindering treatment of wastewater as a remedy to pollution in developing countries have also been discussed. The methodology used in this paper is based on literature review of the most current issues that affect water resources world-wide. The review is limited to scientific facts and no political factors affecting water resources have been included.
It has been found that although Uganda is endowed with 66km 2 /year of renewable water resources, population increase, deforestation, degradation of wetlands and pollution are major
threats to its water resources. Problems associated with water quality and quantities are more likely to result into internal conflicts which are bound to spread beyond Ugandan borders.
Chapter 15 - Water is a vital aspect of hemodialysis. During the procedure, large volumes of water are used to prepare dialysate and to clean and reprocess machines. This paper evaluates the technical and economical feasibility of recycling hemodialysis wastewater for irrigation uses, such as watering gardens and landscape plantings. Water characteristics, Chapter 15 - Water is a vital aspect of hemodialysis. During the procedure, large volumes of water are used to prepare dialysate and to clean and reprocess machines. This paper evaluates the technical and economical feasibility of recycling hemodialysis wastewater for irrigation uses, such as watering gardens and landscape plantings. Water characteristics,
Kay W. Canton
comparison of intended cost with that of seawater desalination, which is widely used in irrigation.
Chapter 16 - Heavy metal pollution is a serious problem in many developed and developing countries. Lead had been recognized as a particularly toxic metal and comes into water bodies mainly from metallurgical, battery, metal plating, mining and alloy industries. In order to minimize the impacts of this metal on human health, animals and the environment, lead-contaminated water and wastewater need to be treated before discharge to water bodies.
This chapter concerns an investigation of potential usage of corn-processing wastewater as a new alternative low-cost substrate to produce biosorbent and evaluate this biosorbent to remove Pb(II) ions from aqueous solutions. For this aim, Rhizopus oligosporus cultivated on corn-processing wastewater and dried biomass of these fungi was used as an adsorbent. The adsorption experiments were conducted in a batch process and the effects of contact time (1-
48 hours), initial pH (2-7), initial metal ion concentration (20-100 mg L -1 ) and adsorbent dosage (0.5-5 g L -1 ) on the adsorption were investigated. Pb (II) ion concentrations before and
after adsorption were measured using Inductively Coupled Plasma-Mass Spectrometry. Maximum adsorption capacity was achieved at pH 5.0. The isothermal data of dried fungal biomass could be described well by the Langmuir equation and monolayer capacity had a mean value of 59.88 mg g -1 . The pseudo-second order reaction model provided the best description of the data with a correlation coefficient 0.99 for different initial metal concentrations. This result indicates that chemical sorption might be the basic mechanism for this adsorption process and Fourier Transform Infrared Spectroscopy analyses showed that amide I and hydroxyl groups play an important role in binding Pb (II).
Because of the high activation capacity of adsorbent and low cost of process dried R. oligosporus biomass presents a good potential as an alternative material for removal of Pb (II) ions from the aqueous solutions.
Chapter 17 - The main objective of this research work is to determine the presence of di(2-ethylhexyl) phthalate, di(2-ethylhexyl) adipate and diisodecyl phthalate, in different water samples (drinking waters, effluents and surface waters). Different analytical methods were studied in order to know the best methodology for the quantification of these compounds. Solid-liquid and liquid-liquid extraction were investigated and finally the liquid- liquid extraction and analysis by gas chromatography followed by mass spectroscopy was chosen because of offering the highest recovery rate. In the whole of this research study, the control of background pollution by reagents and material was extremely important. The problem of background pollution is more serious in the trace analysis of phthalates and adipates as a consequence of their presence in almost all equipment and reagents used in the laboratory.
Respect to the control of the selected plasticizers in the different water samples, bis (2- ethylhexyl) phthalate and bis (2-ethylhexyl) adipate were detected in drinking water, effluents and surface waters. On the other hand, diisodecyl phthalate was not detected in any sample.
In: Fluid Waste Disposal ISBN: 978-1-60741-915-0 Editor: Kay W. Canton, pp. 1-48
© 2010 Nova Science Publishers, Inc.
Chapter 1 T REATMENT OF W ASTEWATER BY E LECTROCOAGULATION M ETHOD AND THE E FFECT OF L OW C OST S UPPORTING E LECTROLYTES
1 1 Lazare Etiégni 2 , K. Senelwa , B. K. Balozi , K. Ofosu-Asiedu ,
3 1 A. Yitambé 1 , D. O. Oricho , and B. O. Orori
1 Moi University, Department of Forestry & Wood Science, P. O. Box 1125 Eldoret, Kenya.
2 J.I.C., Dept. of Chem. Eng. Box 10099, Jubail Industrial City-31961,
Kingdom of Saudi Arabia.
3 Kenyatta University, Department of Public Health
P.O Box 43844-00100 Nairobi, Kenya
A BSTRACT
Coagulation and flocculation are traditional methods of treating of polluted water. Electrocoagulation (EC) presents a robust novel and innovative alternative in which a sacrificial metal anode doses water electrochemically. This has the major advantage of providing active cations required for coagulation, without necessarily increasing the salinity of the water. Electrocoagulation is a complex process with a multitude of mechanisms operating synergistically to remove pollutants from water. A wide variety of opinions exist in the literature for key mechanisms and reactor configurations. A lack of a systematic approach has resulted in a myriad of designs for electrocoagulation reactors without due consideration of the complexity of the system. A systematic, holistic approach is required to understand electrocoagulation and its controlling parameters (pH, temperature, conductivity, current density). This will enable
a priori prediction of the
treatment of various pollutant types. Electrocoagulation involves applying a current across electrodes in water. This results in the dissolution of the anode (either aluminum or iron). These ions then form hydroxides which complex with and/or absorb contaminants and precipitate out. The precipitate with the contaminants can then be
2 Lazare Etiégni, K. Senelwa, B. K. Balozi et al. removed from the water by settling and decantation or filtration. EC has the potential to
be applied in many other areas besides the textile and semiconductor industry. It has been successfully tested in the pulp and paper industry, as well as tea and coffee processing. However over electrical potential within electrodes during electrocoagulation normally causes extra voltage, which wastes energy. There have been attempts to reduce this extra voltage which, in these days of World energy crisis, will render the electrocoagulation process uneconomical. The inclusion of supporting electrolyte such as NaCl achieves this. One of the methods pioneered by researchers at Moi University in Kenya is the use of wood ash leachate as supporting electrolyte which in some cases could reduce energy consumption by as much as 80%. Other supporting electrolytes tested are ash from bagasse and from coffee husks. These supporting electrolytes are relatively inexpensive, but they all generally result in large amount of coagulated sludge. Other supporting electrolytes such phosphate rock are less effective than wood ash, but they yield almost 50% less sludge after electrocoagulation. Most of the supporting electrolytes have an added advantage of reducing other wastewater pollution parameters such as BOD, COD, TSS, TS, turbidity, pH and color. Because of the inherent benefits of these low cost supporting electrolytes, electro-chemical methods could be a credible alternative to more traditional wastewater treatment approaches.
I NTRODUCTION
With the dwindling availability of water resources in the World coupled with high population growth, pressure is being exerted on water and wastewater plant managers the world over to find cost-effective methods to treat a wide range of wastewater pollutants in a diverse range of situations. Traditionally coagulation, flocculation and lagooning have been used as chemical and biological processes with varying degrees of success to treat polluted waters. However a more cost-effective and proven method to clean an ever widening range of water pollutants, on-site, and with minimum additives, is required for sustainable water and wastewater management. Electrocoagulation treatment of water seems to fit this description.
Colloidal dispersions in water or wastewater often referred to as sols consist of discrete particles held in suspension by their extreme small size (1-200 nm), state of hydration (chemical combination with water), and surface electric charge. The chemistry of coagulation and flocculation is primarily based on the electrical properties of the particles. Like charges
repel each other while opposite charges attract. Particles finer than 0.1 µm (1x10 -7 m) in water or wastewater remain continuously in motion due to electrostatic charges (often negative)
which cause them to repel each other. There are two types of colloids - hydrophilic and hydrophobic. Hydrophilic are readily dispersed in water and their stability depends on the affinity for water rather than the slight negative charge they possess. Hydrophobic colloids on the other hand have no affinity for water and their stability depends on the charge they possess, usually positive. The electrostatic repulsion between the colloidal particles leads to a stable sol. The surface or primary charge of colloidal particles comes from charged groups within the particles or the adsorption of charged particles. The sign and magnitude of the surface charge depends on the character of colloids, the pH (the lower the pH the more positive the charge becomes), the ionic strength and the characteristics of the water or wastewater.
3 theory applied to hydrophobic colloids (Figure 1), and can be estimated using
Treatment of Wastewater by Electrocoagulation Method …
Smoluchowski ‘s (1872-1917) electrokinetic mobility equation:
where μ = the electrophoretic mobility = zeta potential ε = the electric permittivity = the viscosity of the water or wastewater
Zeta potential can also be calculated using the following relationship for electrostatic force
δπqd
q = charge per unit area
d = thickness of the layer surrounding the shear surface through which the charge is effective π = pi (= γ.1δβ8ε7)
D = dielectric constant of the liquid
Stern layer
Surface shear +
Particl e Bulk of
solution
Electric
potential surrounding
particle
Zeta potential
Diffusion
layer of counterions
Fixed layer of ions
4 Lazare Etiégni, K. Senelwa, B. K. Balozi et al.
The diffused double layer (Figure 1) consists of two parts: an inner region, also referred to as Stern layer, which includes ions bound relatively strongly to the surface (including specifically adsorbed ions) and an outer, diffuse or movable region in which the ion distribution is determined by a balance of electrostatic forces and random thermal motion. The potential in this region, therefore, decays as the distance from the surface increases until, at sufficient distance, it reaches the bulk solution value, conventionally taken to be zero. The repulsive force of the charged double layer scatters particles thus preventing agglomeration. Particles with high zeta potential have