International Journal of Environment and Bioenergy ISSN

International Journal of Environment and Bioenergy, 2013, 6(2): 117-145 International Journal of Environment and Bioenergy ISSN: 2165-8951 Florida, USA Journal homepage: www.ModernScientificPress.com/Journals/IJEE.aspx Review

Current Research Trends in Wastewater Treatment-A Review Ashok K. Pandit 1, Dilafroza Jan 1, *, Azra N. Kamili 1, Basharat Mushtaq 2 1

Centre of Research for Development, University of Kashmir, Srinagar-190006, Jammu & Kashmir, India

2

Department of Environmental Science and Limnology, Barkatulla University, Bhopal, M.P, India

* Author to whom correspondence should be addressed; E-Mail: [email protected] Article history: Received 6 April 2013, Received in revised form 4 June 2013, Accepted 6 June 2013, Published 10 June 2013.

Abstract: The literature on different aspects of wastewater treatment is quite voluminous. A review of the research trends, followed in wastewater treatment, is discussed by several researchers. A comprehensive review on treatment of sewage is extremely difficult to compile mainly due to its voluminous nature and the difficulty in obtaining the scattered information as isolated pieces of research. The available information pooled together in the present review is a suitable continuation and supplement to the papers, published earlier by authors regarding the subject matter. Keywords: wastewater; sewage treatment plant; secondary treatment; indicator; trace metals.

1. Introduction Today with the increase in world population, the water consumption has increased manifold which caused increase in the sewage effluents. Domestic sewage is mainly comprised of water (99.9%) together with moderately small concentrations (0.1%) of suspended and dissolved organic and inorganic solids (Mara and Cairncross, 1989). In developing countries, a major portion of the population lacks access to safe drinking water and sanitation, which has been related with high incidence of waterborne diseases (WHO and UNICEF, 2000). Sewage treatment is the process of Copyright © 2013 by Modern Scientific Press Company, Florida, USA

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removing pollutants from domestic sewage and effluents from industries, tanneries and distillaries. Physical, chemical and biological pollutants are removed by various physical, chemical and biological processes. Wastewater treatment aims at to generate an effluent and a solidified material known as sludge which is appropriate for discharge or reuse back into the surroundings (Metcalf and Eddy, 1991).

2. An Overview The concept of wastewater reuse is not new. Paris for the first time in 1868 used sewage farms for its purification. Between 1850’s and 1940’s the major purpose of wastewater treatment was mainly focused on the removal of organic matter and suspended solids, followed by the unintentional removal of nutrients. Later in 1915 Egyptians used sewage effluents for the purpose of irrigation. In developing countries 80% of the domestic sewage is being currently used for seasonal irrigation of agricultural land (UNDP and WB, 1990). In Latin America about 15% of the collected wastewater is being given proper treatment (Nuhoglu et al., 2004). In Venezuela, which is an under developed country in South America with respect to wastewater treatment, 97% of the sewage is being discharged raw into the environment (Kumar et al., 2010). In Iran (Tehran), majority of populations discharges untreated sewage into the city’s ground water (Tajrishy and Abrishamchi, 2005; Kumar et al., 2010). However, in USA almost no wastewater is discharged into the nearby water bodies without treatment. In New York, large centrifuges are used in sewage treatment systems to extract maximum amount of water. In India treated or partially treated or untreated wastewater is disposed off into natural drains joining water bodies. This water is used for different purposes like irrigation and fodder cultivation. In India the wastewater which is disposed off into natural drains is used in agricultural lands. In the South-East Asian region including India, recent technologies for the treatment of wastewater are being employed which are comprised of Fluidized Aerobic Bed (FAB), Anaerobic Filter (AF), Expanded Granular Sludge Blanket (EGSB), Sequencing Batch Reactor (SBR), Membrane Bioreactor (MBR), Fluidized Aerated Bed Reactor (FAB), Submerged Aeration Fixed Film Reactor (SAFF), BIOFOR (Biological Filter Oxygenated Reactor) and Upflow Anaerobic Sludge Blanket (UASB) process. UASB technology has been known as one of the most cost effective and promising sewage treatment process taking into consideration the environmental necessities in India (Khalil et al., 2008). India is one of the leading countries in terms of the amount of sewage volume treated by the UASB process (Khalil et al., 2008). Presently, there are about 23 full-scale UASB plants in operation at various places in India with total installed capacity of about 985,000 m3/day (985 MLD) and about 20 number are in pipeline which are likely to be commissioned within next 3-4 years (Khalil et al., 2008). With financial assistance from international funding agency, the National River Conservation Copyright © 2013 by Modern Scientific Press Company, Florida, USA


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Directorate (NRCD), under the Ministry of Environment and Forests (MoEF), Government of India (GoI), formulated and launched a comprehensive action plan project for conservation of the River Yamuna under which 16 UASB sewage treatment plants (STPs) were commissioned in the period of 1999-2002 (Khalil et al., 2008). The Indian government felt a need to prevent the pollution of its water resources and formulated an action plan viz., Ganga Action Plan (GAP) in 1986 and later on Yamuna Action Plan (YAP) in early 1990 (Khalil et al., 2008). In India, Brazil and Columbia, UASB technology has been used for the treatment of domestic wastewater which is now being used and gaining popularity in other countries (Seghezzo et al., 1998). In Indian context there has been a lot of contribution by various workers in the field of wastewater treatment (Nandy and Kaul, 1994; Kapur, 1999; Karthikeyan and Sabarathinam, 2002; Nageshwara et al., 2002; Rajasimman and Karthikeyan, 2004; Subhash et al. 2004; Varughese et al., 2004; Rajasimman and Karthikeyan, 2006; Banu et al., 2007; Khalil et al., 2008; Kumar et al., 2010; Desai, 2011; Kumar et al., 2012). However, in Jammu and Kashmir hardly any work in the field has been carried out and practically there are no published reports. In many developing countries UASB process is used to treat wastewater, which alone cannot efficiently purify it. Therefore, there is a need of post-treatment to further treat the effluents (Draaijer et al., 1992), which may be in the form of huge ponds and lagoons (Maynard et al., 1999), submerged aerated biofilter (Collivignarelli et al., 1990), aerobic fluidized bed (Kim et al., 1997), rotating biological contactor (RBC) (Castillo et al., 1997), down-flow hanging sponge cubes (Machdar et al., 1997) and activated sludge (Sperling et al., 2001). But the application of such high-rate systems need high-investment, operation and maintenance costs and replacement of mechanical equipments like aerators, recirculation pumps, and RBC shaft and bearing (Mba et al., 1999). In addition to this, the combination of lagooning system with trickling filter has been practised in Zimbabwe and Kanyamazane which showed a high potential of pathogen, conductivity and nitrite removal (Broome et al., 2003). Some researchers have reported some enhancements and details of one of the important treatment systems i.e., the oxidation ponds. Oxidation ponds are extensively used for the treatment of individual wastewater and mixtures of industrial and domestic wastewater amenable to biological treatment (Metcalf and Eddy Inc., 2003). Bahlaoui et al. (1997) studied the spatio-temporal dynamics and removal efficiency of pollution indicator (total coliforms, faecal coliforms and faecal Streptococci) and some pathogenic bacteria (Pseudomonas aeruginosa and Aeromonas spp.) in two high rate oxidation ponds (HROP) pilot plants. Further, investigation revealed that the removal efficiency of faecal-indicator bacteria by HROP was found to be higher in summer than winter. Hamouri et al. (1994) while working on oxidation ponds obtained a removal of 80% for BOD and 76.5% for COD removals as well as 91.66% of total coliforms, 99.98% of faecal coliform and 99.89% of faecal

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Streptococci removal during wastewater treatment in a HRAP (High Rate Algal Pond) system. They also studied the effect of season on faecal coliform and faecal Streptococci removal rates. One more important sewage treatment type that is widely used includes waste stabilization ponds. 2.1. Effect of Untreated or Partially Treated Water Significant relationship exists between the quality of the final effluent and the receiving water body. Chemical and microbiological changes occur in water bodies as a result of various anthropogenic activities especially due to the discharge of raw wastewaters into the receiving water bodies such as streams, rivers, lakes and ponds (Gieldereich, 1990; Momba et al., 2006). Such activities increase treatment costs and discharge of a variety of potentially pathogenic microorganisms to waters, thereby causing waterborne diseases with many health impacts and socio-economic effects (Craun, 1991) and a reduction in the quality of water (Bahlaoui et al., 1997; Simpson and Charles, 2000). Pandit and Kumar (2008) have opined that the entry of domestic sewage into the Dal lake has not only resulted in excessive growth of macrophytes but also undesirable change in the biotic set up and deterioration of water quality. Igbinosa and Okoh (2009) from their study revealed that there was an adverse impact on the physico-chemical characteristics of the receiving watershed as a result of the discharge of inadequately treated effluents from the wastewater treatment facility which poses a health risk to several rural communities which rely on the receiving water bodies primarily as their sources of domestic water. Momba et al. (2006) determined that the nutrients, total nitrogen, dissolved oxygen (DO), BOD and the microbiological species discharged from all the plants did not comply with the European Union (EU) guidelines for the protection of the aquatic ecosystems, thereby posing threat to the environment. Daniel et al. (2001) while investigating the efficiency of a sewage treatment plant installed in the catchment of one of the streams of the Piracicaba river basin, southeast region of Brazil observed an increase in the O2 concentration after the beginning of the treatment, and decrease of Dissolved Inorganic Carbon (DIC) and Dissolved Organic Carbon (DOC) concentrations especially during the low water period. However, no significant change was observed in the EC, suggesting that the concentrations of major ions was still unaltered and secondary treatment is necessary in order to reduce ion load into the stream. Sumithra and Narayan (2003) observed that higher BOD, COD values and physico-chemical concentrations in both effluent and sewage has influenced the downstream area of River Bhadra. Morrison (2001) and Fatoki et al. (2003) examined the Keiskammahoek sewage treatment plant and Keiskammahoek river respectively in Eastern Cape, South Africa and concluded that pH, electrical conductivity and nitrate levels in effluents were below guideline values. However, significant pollution of the river was found due to orthophosphate, COD and NH4-N from the point source. Varughese et al. (2004) studied the impact of inefficiency of aeration and ozonier units on the Copyright © 2013 by Modern Scientific Press Company, Florida, USA


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liminological characteristics of a tropical sewage fed lake in Bhopal. The lake receives a large amount of raw sewage from its densely populated habitation. The continuous input of biologically active nutrients through inflow of sewage has changed the water body into a eutrophic lake resulting in frequent oxygen depletion in the hypolimnion. 2.2. Efficiency of Wastewater Treatment Plants The waste stabilization efficiency of a wastewater treatment plant (WWTP) is dependent upon the type of sewer collection system, type of waste entering the sewer, type of wastewater treatment technology, the quality of domestic water and the standard of living of consumer's community. The extent of desired treatment is evaluated by the essential uses of the receiving water body and reuse for diverse reasons (Hammer, 1996). The diurnal variation has been shown to influence the quality of the final effluent (Hodgson, 2003). The most important factor that affect the removal efficiency of treatment plants includes seasonal changes as revealed by Hodgson (2007) in his study on the performance of the Akosombo waste stabilization ponds in Ghana. The final effluents in the rainy season were found to be less polluted than those of the dry season which may be due to the dilution of the effluent by rain water. There are other factors that affect the removal efficiency of wastewater treatment plants which include the type of wastewater treatment system, temperature, dissolved oxygen, pH, the time of sampling during the day and light intensity available (Kantachote et al., 2009). Rouse et al. (2004) reported that higher treatment rates are achievable due to selective retention of large amounts of effective biomass with no need for sludge recycle. Preliminary treatment is efficient in removing 35% of the BOD, 30% of the COD, 60% of the TSS and only 10 – 20% of the total nitrogen and total phosphorus (Radojevic and Bashkin, 1999). This removal efficiency depends upon the concentration, the retention time in the sedimentation tank and the evenness of distribution and flow in the tank. Removal efficiency of nitrogen and phosphorus in mechanical treatment plants is only 10%. However, in case of sewage treatment plants equipped with the mechanical and biological technology, the efficiency of nitrogen and phosphorus removal is assumed to be 50% and 40%, respectively. For mechanical-biological sewage treatment plants with improved tertiary sewage treatment the degree of reduction for both nitrogen and phosphorus was assumed to be 88%. In most studies significant reduction has been observed at outlet sites of STPs (Kumar et al., 2010; Desai, 2011; Saha et al., 2012). However, some studies have shown little or no reduction of pollutant concentration (Howard et al., 2004; Momba et al., 2006; Antunes, 2007; Kay et al., 2008; Akpor, 2011) which is a major concern for water bodies as well as public health. The comparative studies between STPs have shown both significant and insignificant variation in efficiency rates (Jamwal et al., 2009; Kumar et al., 2010). In past some studies have also shown that Copyright © 2013 by Modern Scientific Press Company, Florida, USA


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STPs deviate from normal permissible limit which have been given by WHO and EPA (Momba et al., 2006; Antunes, 2007; Akpor, 2011). 2.3. Inefficiency of Wastewater Treatment Plants Better the quality of the final effluent, better is the quality of the receiving water body. The inefficiency of sewage treatment plants and their effluents affect the receiving water bodies (Momba et al., 2006). The prevalence of infective agents in the final effluents after the treatment process is an indication of the inefficiency of the wastewater treatment plants for the removal of the pathogens, and the outcome of poor disinfection practices and poor maintenance of the infrastructure (Pearson and Idema, 1998) especially when the receiving water is used for domestic, recreation and agricultural purpose (Tchobanogeuos, 1979). The efficiency of sewage treatment plants is measured in terms of removal of organic matter (CPHEEO, 1993). Colmenarejo et al. (2006) and Sincero and Sincero (1996) determined the general efficiency indicator in terms of average TSS, COD, BOD and ammonia removal efficiencies. There are several factors that are responsible for the inefficiency of a wastewater treatment plant viz., poor conditions of sewerage system, improper design of the plant and organizational problems (Storhaug, 1990), overloading and discharge of industrial effluents (Dakers, 1990; Morrison et al., 2001; Bataineh et al., 2002), chemical shock, inadequate mixing in the equalization tank and inappropriate C/N/P ratio in anaerobic and aerobic tanks (Sadeghpoor et al., 2009), short retention time (Awuah and Abrokwa, 2001) and the treatment efficiency may be affected when the system is hydraulically under loaded (Kapur, 1999). Nageshwara et al. (2002) assessed the quality of raw and treated sewage effluents from Hussain Sagar Amber pet treatment plants of Hyderabad city and reported that the concentration of various parameters viz., alkalinity, chlorides, pH, dissolved solids, electrical conductivity and BOD do not decrease with the treatment and the chloride concentrations are well within the limits in both raw and treated water. Except turbidity, all other parameters have not changed even after treatment. The BOD of the effluent in both the treatment plants has increased. Dulkadiroglu et al. (2005) reported that a potential drawback of biofilm processes is diffusion limitation of substrates and oxygen across biofilm layers, which becomes more critical with increasing biofilm thickness. Pehlivanoglu-Mantas and Sedlak (2006) reported that waste water treatment plants designed for nitrification and denitrification can remove 80 to 95 percent of inorganic nitrogen, but the removal efficiency of organic nitrogen is typically much less efficient. 2.4. Physico-chemical Characteristics of Wastewater Domestic wastewater represents the mixture of grey water and black water. It is mainly Copyright © 2013 by Modern Scientific Press Company, Florida, USA


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comprised of water (99.9%) together with moderately small concentrations (0.1%) of suspended and dissolved organic and inorganic solids (Mara and Cairncross, 1989). When present in sewage, approximately 50% of this material is dissolved and 50% is suspended (Obuobie et al., 2006). Organic portion of sewage is mainly composed of carbohydrates, lignin, fats, soaps, synthetic detergents, proteins and their decomposition products, as well as various natural and synthetic organic chemicals from process industries, cooking oil and greases (Al Zubeiry et al., 2005). Inorganic compounds include chloride, metallic salts and grits (Obuobie et al., 2006). Water temperature represents an important factor, which impacts the acceptability of a number of inorganic constituents and chemical contaminants (WHO, 2006). Temperature has got impact on the removal efficiency of WWTPs. Kassab et al. (2010) indicated that the removal efficiency of COD from wastewater treatment using upflow anaerobic sludge blanket (UASB) with activated sludge (AS) or sequencing batch reactor (SBR) system was in the range of 79 to 85% at low temperature. They ascribed that to the integration of UASB with SBR which especially enhance the removal efficiency of organic content of effluent whereas the removal efficiencies of TN and ammonia were 20 and 100%, respectively. Similar results were reported by Lema and Omil (2001) who found that the ammonia was removed under moderate to low temperature of sewage treatment using UASB reactor. Luostarinen et al. (2006) also obtained a similar result and they found the percentage of nitrogen removal in the range of 71-77% under anaerobic and at low temperature conditions. Several investigators (Wang, 1994; Elmitwalli et al., 1999, 2000, 2001) revealed that at low temperatures pre-removal of SS is needed prior to anaerobic treatment in a methanogenic sludge-bed reactor. Wang (1994) developed a two-step system, Upflow Anaerobic Sludge Blanket (UASB) + Expanded granular Sludge Blanket (EGSB), for the treatment of domestic sewage at low temperatures. The first-step was aimed at the removal and partial hydrolysis of suspended COD (CODss) and the second-step mainly for conversion of dissolved COD (CODdis) to methane gas. Electrical conductivity of water is a useful and easy indicator of its salinity or total salt content (Morrison et al., 2001). Wastewater effluents possess high concentrations of dissolved salts from domestic sewage (Morrison et al., 2001). Salts such as sodium chloride, and potassium sulphate pass through conventional water and wastewater-treatment plants unaffected (Hammer, 1975). High conductivity of the waste effluents can increase the salinity of the receiving water which may result in adverse ecological effects on aquatic biota (Fried, 1991). The removal of solid material occurs during the primary treatment process (McGhee, 1991). The dissolved form of solids as TDS is removed as effluents and is used for agricultural purposes. High TDS content in effluents decrease the hydraulic conductivity of irrigated land (Bouwer, 1978). Doughari et al. (2007) found no alteration in the dissolved solids in inlet and outlet water samples due



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to low efficiency of treatment plant. Kumar et al. (2010) carried out a comparative study on two different STPs in Karnataka, India and found that the efficiency of two treatment plants was poor with respect to the removal of total dissolved solids. Furthermore, they opined that the problems related to the operation and maintenance of wastewater treatment plants may be the reason for such efficiency. Alkaline pH of the raw sewage mainly occurs due to the sodium hydroxide present in soaps and its acidic nature may be attributed to the anaerobic decomposition that occurs after sampling when kept for hours (Awuah and Abrokwah, 2008). The existence of the most biological life is dependent upon a range of pH and as such affects the performance of a secondary treatment process (Metcalf and Eddy, 2003). Hortskotte et al. (1974) revealed during nitrification process in an activated sludge treatment plant that the hydrogen ions produced neutralize the high pH. However, during denitrification the effluent must be neutralized before discharging it to the anoxic zone. Dissolved oxygen concentrations in unpolluted water normally range between 8 and 10 mg/L (Watson et al., 1985). Concentrations below 5 mg/L adversely affect aquatic life (DWAF, 1996; DFID, 1999). Doughari et al. (2007) observed a decrease in the amount of DO from influent to the effluent. This was attributed to the reduction in amount of impurities during the treatment process. Low DO content in raw sewage may be due to the fact that raw water comes through closed pipes and increased DO in the effluent may be attributed to the effective exchange of oxygen at the air-water interface while treating in open (Awuah and Abrokwah, 2008). Khatri et al. (2003) reported that sewage water is slightly alkaline in reaction and rich in nutrients having high salt content, whereas bicarbonates, sulphates and chlorides were at toxic level. Conclusively, the sewage water can be used for both as a potential source of nutrients as well as water for irrigation. Tchobanoglous et al. (2003) opined that nitrifying bacteria require a significant amount of oxygen to complete the reactions and produce a small amount of biomass; thus causing destruction of alkalinity through the consumption of carbon dioxide and production of hydrogen ions. It was observed that the conversion of one gram of NH3-N to nitrate requires consumption of 4.57 g of oxygen resulting in the formation of 0.16 g of new cells. It was also observed that this process results in the removal of 7.14 g of alkalinity and 0.08 g of inorganic nitrogen being utilized for the formation of new cells. BOD/COD ratio is the most important parameter that helps us to know whether the sewage is biodegradable and to what extent it is biodegradable. For example if the ratio of the mean BOD to COD for the raw sewage is 0.32, it indicates a medium level of biodegradability (Hodgson, 2007). Removal efficiencies of 50-70% for COD have been achieved at COD loading ranging from 1-2 kg COD/m3/d on a variety of wastes at 30 to 35 oC with UASB reactor (Manual on Sewerage and Sewage Treatment, GOI, 1993). Ruiz (1998) conducted a study regarding the treatment of domestic wastewater



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in Spain using UASB system and revealed that the removal efficiency of COD was practically higher than 90% and decreased by decreasing the HRT from 25 to 5 h. He was further of the view that granulation of sludge is an indication of the successful operation of the system. Misrepasi et al. (2006) concluded from their study that COD removal efficiency can be enhanced by enhancing organic upflow rates and upflow velocity, by decreasing hydraulic retention time and by operating the reactors with new sludge in UASB system. Removal efficiencies of 90 – 95% for COD have been achieved at COD loading ranging from 12 – 20 kg COD/m3/d on a variety of wastes at 30 to 35 oC with UASB reactor (Metcalf and Eddy Inc., 2003). Removal efficiency of COD is also dependent on HRT (Zeeman and Lettinga, 1999; Singh et al., 2006; Elmittwalli and Otterpohl, 2007). In the 19th century nitrification concept came into existence and it was considered as a nuisance. After that Arden and Lockett (1914) introduced the concept of activated sludge process. Vast studies have been carried out investigating nitrification and denitrificaton as a tool for the biological removal of nitrogen from wastewater (Sawyer and Bradney, 1945; Ludzack et al., 1962; Wuhrmann, 1962; Downing et al., 1964; Balakrishnan and Eckenfelder, 1970) rising problems in final clarifiers. There are four forms of nitrogen in wastewater viz., ammonia, nitrite, nitrate and organic nitrogen. Organic nitrogen present in sewage is converted to ammonia which is later on assimilated and oxidized to nitrite and nitrate (Sin et al., 2003). In the second step namely denitrification process, nitrate is converted to gaseous nitrogen by bacteria in WWTP which is of particular interest, as nitrates and nitrites are hazardous to human health (Kempster et al., 1997) and, more importantly a main cause of eutrophication (Gray, 2004), is removed from the wastewater. Such microbes are present in almost all aerobic biological treatment processes, but usually their numbers are dependent upon the mean cell residence time and on the BOD5/N ratio (Sotirakou et al., 1999; Sin et al., 2003). Denitrifying bacteria play a major role in the removal of nitrogen compounds from wastewater (Knowles, 1982). The role of these culture dependent organisms in wastewater treatment plants has been studied by Krogulska and Mycielski (1984) and Lim et al. (2005). Little work has been done so far related to the treatment processes that occur within domestic sewage treatment plants (Ahn et al., 2003; Jeon et al., 2003; Lee et al., 2005), and even fewer studies on the diversity of denitrifying bacteria (Kim et al., 2001; Lee et al., 2005). A number of bacterial taxa involved in denitrification within wastewater treatment systems have been reported in Korea, including Pseudomonas, Arthrobacter, Staphylococcus and Bacillus (Kim et al., 2001; Lee et al., 2005). The occurrence of these organisms in a wastewater treatment plant can be estimated by BOD5/N ratio, for e.g. in conventional activated-sludge processes if the BOD5/N ratio is 3, then the fraction of organisms is estimated to be considerably less than 0.083, while as if the BOD5/N ratios is 5 to 9, the estimated percentage is between 0.054 and 0.029 (Metcalf and Eddy, 2003). Tchobanoglous et al. (2003) subdivided advanced treatment, using the terms “secondary with



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nutrient removal” when nitrogen phosphorus or both are removed and “territiary removal” to refer to additional reduction in solids by filters or micro filters. Phosphate in sewage effluents arises from human wastes and domestic phosphate-based detergents (Morrison et al., 2001). Alexander and Stevens (1976) reported an input of phosphorus1.5 and 3.0 g P/cap/d through detergents. The amount of phosphorus in raw municipal wastewater (MWW) varies due to change in life style for instance nutrition, urbanization and industrial development. The study of phosphorus came into existence because of certain discussions on prevention against eutrophication of lakes (Sawyer 1944; Rudolfs, 1947). Phosphates are undesirable anions in receiving waters and act as the most important growthlimiting factor in eutrophication and result in a variety of adverse ecological effects (OECD, 1982; WRC, 2000). Removal of phosphorus was first of all initiated and implemented by the authorities of Great Lakes and agreement was signed between US and Canadian governments in 1972. Removal of phosphorus from the sewage treatment plants occurs by the removal of a portion of the growing biomass (Bond et al., 1999). Phosphorus can be removed from the wastewaters by physical (Reardon, 2006), chemical (Neethling and Gu, 2006) and biological means (Awuah et al., 2004; Strom, 2006). Chemical treatment includes addition of chemicals such as compounds of calcium, aluminium and iron that are used to precipitate phosphorus (Tchobanoglous et al., 2003). These chemicals are usually added before primary settling, during secondary treatment or as a part of a tertiary treatment process (Neethling and Gu, 2006). Drury et al. (2006) and Gnirss et al. (2006) demonstrated that a combination of biological removal and post-chemical treatment in the Clarke County treatment plant can remove effluent phosphorus concentration up to 0.05 mg/L in MBRs. Reardon (2006) suggested two physical methods for phosphorus removal viz., sand filteration (Strom, 2006) and membrane filteration. Different workers suggested different methods for the removal of phosphorus from wastewaters by electroprecipitation (Onsott et al,. 1973), electrolytic treatment (Marson, 1967), ion exchange process (Liberti 1982), crystallization process (Joko, 1984), activated magnesia clinker (Kaneko and Nakajima, 1988), chlorination (Groterud and Smoczynski, 1991) and trickling filter (Dichtl et al., 1994). Biological treatment includes treatment through ponds containing algae and rooted or free floating macrophytes (Awuah et al., 2004) and through phosphate accumulating organisms (PAOs) which store polyphosphate as an energy reserve (Mulkerrins et al., 2003; Strom, 2006). They derive their energy by breaking the phosphate energy bonds of previously stored phosphorus and releasing it to the liquid phase. Workers have found that primary nucleation and molecular growth in FAB is responsible for conversion of phosphate from liquid to solid state and aggregation of primarily formed particles with the grains constituting the media (Rovatti et al., 1995; Seckler et al., 1996).



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The BOD removal and the consequent quality of the effluent depend on the amount of oxygen present, retention time and temperature of the ponds. Effluents with high concentration of BOD can cause reduction of oxygen content which may lead to the development of anoxic conditions in the receiving water body (Hodgson, 2007). Although conventional systems remove most of BOD and other nutrients from wastewaters but waste stabilization pond system has been found to be more reliable (Hodgson, 2007). The mean overall BOD removal efficiency in waste stabilization ponds in Ghana was found to be 77% while other ponds give BOD removal efficiencies greater than 70% (Arceivala, 1981). In another study Abis (2002) reported BOD mean removal efficiency of 91% for pilot scale facultative ponds in the United Kingdom. The BOD removal and the consequent quality of the effluent depend on the amount of oxygen present, retention time and temperature of the ponds. The percentage reduction of BOD depends upon HRT and increases with increase in HRT but decreases with increase in initial substrate concentration. During the treatment process BOD decreases which has certainly an effect on coliform levels (Rajeb et al., 2011). The reduction of BOD simultaneously decreases the coliforms (Der Steen et al., 2000). There are certain species of fungi which are readily adaptable to the reduced conditions of oxygen supply in the sewage treatment plant (Tabak and Cooke, 1968) and these can help in the reduction of the biochemical oxygen demand of the habitat (Cooke and Busch, 1957), and can derive nutrients from this habitat (Cooke and Busch, 1958). Kumar et al. (2010) used the regression analysis between the influent BOD and the influent TSS and variation of removal efficiency of BOD with removal efficiency of TSS. He opined that these correlations can be very useful as BOD measurement will take 5 days. Once the correlation has been established, TSS measurement can be used to good advantage for the control and operation of treatment plant. 2.5. Role of Microbes in Wastewater Treatment Plants 2.5.1. Bacteria In addition to physical, chemical and biological contaminants, wastewater also possesses pathogenic bacteria which may spread diseases through being directly or indirectly ingested into the human body (Dudley et al., 1980; WHO, 1981, 1989; Feachem et al., 1983; Shuval et al., 1986). Larkin et al. (1978) and Epstein et al. (1982) have proved that vegetables become contaminated with pathogenic organisms when irrigated with sewage water and when these vegetables are consumed, they could produce diarrhea, salmonellosis and shigellosis (Dunlop and Wang, 1961; Kowal et al., 1980; Rosas et al., 1984). Bacteria are the most commonly used indicators for the routine monitoring of faecal contamination and, therefore, total coliforms (TC) and faecal coliforms (FC) indicate the possible presence of viral or bacterial pathogens in the effluent of sewage treatment plant and receiving waters (Bitton, 2005; Kantachote et al., 2009). The elimination of different bacterial species in Copyright © 2013 by Modern Scientific Press Company, Florida, USA


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treatment plants depends upon different survival rates and their increased resistance to the chemicals, flocculation and precipitation (Saleem et al., 2000; Lucena et al., 2004), geographical differences (Fleisher et al., 2000; Lucena et al., 2004) and treatment processes (Horan et al., 2004; Wery et al., 2008). Moura et al. (2007) and Rawat et al. (1998) indicated that temperature, dissolved oxygen and pH are the variables that mainly influence the bacterial communities. With increase in temperature, pH, level of insulation and residence time the coliform reduction increases (Arridge et al., 1995; Davies-Colley et al., 1997) but shows a negative correlation with light intensity and DO (Kantachote et al., 2009). Tandukar et al. (2005) proposed a system consisting of UASB and the fourth-generation Downward Hanging Sponge (DHS) due to which there occurred a remarkable decrease in organic and nutrient removal (96% removal for BOD) and coliform removal. In DHS coliforms are removed by entrapment or adsorption, predation, natural die-off and toxicity of oxygen (Tawfik et al., 2004). The main factors involved in bacterial reduction in waste stabilization ponds are retention time (Lloyd et al., 2002; Hodgson, 2007), organic load, starvation, wind velocity, ponds geometric form, the exposure to sunlight (Curtis et al., 1992; Hodgson, 2007), pH (Davies-Colley et al., 1999; Hodgson, 2007) and temperature (Hodgson, 2007). In wastewater treatment plants the biological agents like bacteria are removed in different stages. Firstly in primary treatment most of bacteria remain firmly adhered to solid particles; aeration and clarification removes bulk of the bacteria by physical processes like flocculation (Gerba, 1999). The treated liquid effluent still contains significant loads of bacteria which are later on removed by chlorination/disinfection methods to concentrate in sludge (Chitnis et al., 2004). Removal of pathogens and indicator organisms like total coliform (TC), faecal coliform (FC) and faecal Streptococci (FS) is carried out by chemical agents (chlorination), physical processes (heating), mechanical means (sedimentation), or radiation (ultraviolet disinfection) (Metcalf and Eddy, 1991), or elevated concentrations of dissolved metals and extreme pH (Rogers and Wilson, 1966; Wortman et al., 1986). Dungeni et al. (2010) found combination of sedimentation, rapid sand filtration and chlorination processes a major prerequisite for the reduction of turbidity, pathogenic bacteria and viral indicators. Koivunen et al. (2003) found that rapid sand filtration along with the addition of poly-aluminium chloride reduced the microorganisms, suspended solids and nutrients from the treated wastewaters. The process of precipitation by means of coagulant and biological treatment has same level of removal efficiency (Nieuwstad et al., 1988; Koivunen et al., 2003). Generally biological–chemical treatment process may achieve 90–99% microbial reductions, but in some cases reductions may be poor as pathogenic microorganisms have got the ability to multiply in wastewaters or wastewater treatment plants (de Zutter and Hoof, 1984; Emparanza-Knorr, 1995). In case of ASP the pathogenic removal depends upon the treatment process type, retention



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time, other biological flora present in activated sludge, O2 concentration, pH, temperature and the efficiency in removing suspended solids (de Zutter and Hoof, 1984; Kayser et al., 1984; Popp, 1973; Yaziz and Lloyd, 1979). Higher temperature of wastewater increases biological activity (predation by bacteria) (Yaziz and Lloyd, 1979; Koivunen et al., 2003). During the process of precipitation hydroxide flocs are formed that adsorb impurities and microorganisms. The rapid sand filteration remove contaminants more efficiently than biological treatment (Teitge, 1986 ) due to efficient and continuous backwash and the smaller sand particle size of rapid sand filter (Koivunen et al., 2003). Al Zubeiry (2005) reported that microbial load was relatively higher in raw sewage than in secondary effluent and dewatered sludge. He recorded faecal Streptococcus, Streptococcus pneumonia, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus and Escherechia coli in the three substrates at 37 oC. He isolated Salmonella spp. from raw sewage and secondary effluent, but Shigella spp. only from raw sewage. Samie et al. (2009) carried out a study on 14 sewage treatment plants in the Mpumalanga Province, South Africa and reported that all the STPs reduced turbidity and some microbes while some of the microbes were retained in the final effluents, therefore there is a need for renovation of treatment plants with the adoption of biological treatment by the use of trickling filters in combination with ponds or activated sludge system. Winfrey et al. (2010) found that the co-treatment of municipal wastewater and synthetic acid mine drainage when mixed together reduced faecal indicator bacteria more effectively (100%) than conventional treatment systems as the acid mine drainage has deleterious effects on faecal indicator bacteria. Same results were obtained by Joseph and Shay (1952). Their studies also revealed that treating wastes in such a manner could save resources and alleviate some of the infrastructure challenges of building separate treatment systems in areas where these two waste streams are prevalent. However McCullough et al. (2008) gathered very limited FC data that suggested counts may be reduced via co-treatment. Saha et al. (2012) found both Gram positive (Bacillus, Aureobacterium and Kurthia) and gram negative bacteria (Zoogloea, Yersinia, Citrobacter and Pseudomonas) where in they opined that Zoogloea along with other free flowing aerobic heterotrophic bacteria like Bacillus and Pseudomonas could play the major role in the sewage treatment. 2.5.2. Fungi Wastewater pathogens in addition to bacteria include one more diverse group that if discharged into the environment pose serious health risks include fungi (Velez and Diaz, 1985; Bunse and Merk, 1992; Al-Zubeiry, 2005). Kolwitz (1901) for the first time used the term “Abwassepilz” or “sewage fungus”, for Leptomitus lacteus. Ample work has been done on fungi in WWTPs number of times (Abdel Hafez and El-Sharouny 1990; De Hoog et al., 2000; Ulfig et al., 2003, 2005; Maruthi et al., 2012). Fungi have been recovered in large numbers in both sewage (Gray, 1982; Abdel-Hafez and ElCopyright © 2013 by Modern Scientific Press Company, Florida, USA


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Sharouny, 1987; Abdel-Mallek et al., 1988; Ismail and Abel-Sater, 1994), sewage treatment plants and in natural stream reaches which receive effluents from STPs (Cooke, 1970). The most common fungal groups present in wastewater include yeasts, mould fungi (Aspergillus, Fusarium, pencillium, etc.) and the family Mucoraceae (Kacprzak et al., 2003; Kacprzak et al., 2005; Sammon et al., 2010) and their treatment process had an effect on the reduction of the number of colony forming units (Kacprzak et al., 2005). Out of which some species are well known mycotoxin producing fungi (Aleksandrowies and Smyk, 1973; Pitt, 1994; Tseng, et al., 1995). Some species are pathogenic (Wadhwani and Srivastava, 1985; Pitt, 1994) and some are potential facultative causative agents of different mycotic infection (Velez and Diaz, 1985). Fungal pathogens and their toxic compounds in the sewage treatment plant may spread through sludge and sewage, as well as through aerosols (Hickey and Reist, 1975; Bausum et al., 1982). The source of fungal species in wastewater treatment plants is the sedimentation from the air (Cooke, 1970), municipal wastewaters and from people and animals (Biedunkiewicz and Ozimek, 2009). The number of fungi in wastewater is determined by the amount of organic matter present; higher the nutrient concentration, higher is the fungal population (Simard 1971; Biedunkiewicz and Ozimek, 2009) but reduces the fungal diversity (Cooke 1970). This could explain the observed increase in numbers of some genera: Chrysosporium spp., Geotrichum spp., Cladosporium spp., Gliocladium spp., Paecilomyces spp., and Pencillium spp. in sewage receiving soils (as compared to nonpolluted soils) which seem to be less sensitive to soil contamination by organic pollutants of raw city wastewater. In fact, some of the fungi in this group (Geotrichum spp. and Chrysosporium spp.) were found to be associated with organic wastes (Simard, 1971). According to Cooke (1965) fungi can tolerate high levels of pollution even which is difficult to decompose. Nielowak (1974) demonstrated that dilution of organic matter by seasonal water flows brings about good aeration of the wastewater and causes a decrease in the fungal population. 2.6. Trace Metals in Wastewater Besides disruption of natural process, urban sewage is being considered a potential source of heavy metals in the aquatic ecosystems, pathogens and drugs, including carcinogenic compounds (Roll and Fujioka, 1997; Higuti et al., 1998; Ternes, 1998; Donnison and Ross, 1999; Sanudo-Wilhelmy and Gill, 1999; Ono et al., 2000). Due to rapid industrialization and urbanization trace metals are being discharged into the wastewaters resulting in pollution of wastewaters (Rai and Tripathi, 2008; Zhuang et al., 2009; Rai, 2010) which may pose a serious threat and health hazard (Borah et al., 2009; Sharma et al., 2009). The metal pollutants of serious concern due to their carcinogenic and mutagenic nature include Pb, Cr, Se, Zn, As, Mn, Cd, Au, Ag, Cu and Ni (Ahalya et al., 2005). Partially treated or treated sewage is a possible source for contamination of irrigated soils and vegetables (Khatri et al., Copyright © 2013 by Modern Scientific Press Company, Florida, USA


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2003; Singh et al., 2005; Rai and Tripathi, 2007). Haruna et al. (2009) observed high levels of metals like Pb, Cu and Cd in sewage and later on found the high levels of the same metals in soil and vegetables that were irrigated by using sewage water. Removal of metals in dissolved form occurs by means of primary settling but the larger fraction of metals is removed in the aeration tank by adsorption to the biological floc (Oliver and Cosgrove, 1974) and is finally retained in the sludge. The removal of trace metals during primary sedimentation follows the sequences particulate metal in large particles followed by particulate metals in small particles and then dissolved metals (Scoullos et al., 2007). Tertiary treatment is modified to remove most of the metal concentration (Oliver and Cosgrove, 1974). The removal efficiency of trace metals depends upon pH and type of growth in treatment plant. For instance, pH levels higher than 8 cause metal ions to precipitate and allow purification process to occur normally in waste stabilization ponds (Hodgson, 2003). Sometimes higher concentrations of metal ions (Moshe, 1972) and diurnal variations (Hodgson, 2003) have been found to adversely affect efficiency. Hodgson (2007) found that the trace metal levels (Pb, Zn, Cd and Cr) of the final effluent were all low and insignificant (below the detection limit of < 0.01 mg/L) influenced by the weather conditions and as such the performance. Firfillionis et al. (2004) concluded from his studies that sedimentation process is responsible for decrease in metal concentration. They further illustrated that the variation in removal efficiency depends upon the source of raw wastewater (Villioti, 1998). The low removal efficiency in wastewater treatment plants occurs due to the co-existence of two opposite processes viz., absorption of dissolved metals in the removed sewage sludge and release of metals from small particles (Firfillionis et al., 2004), creating hypoxic conditions in the sedimentation tank (Scoullos et al., 1986), hence releasing higher quantities of trace metals in water bodies (Raco-Rands, 1997; Villaescusa-Celaya, 2000). Polpraseret and Charnpratheep (1989) highlighted that adsorption of metals was increased in attached growth stabilization pond as compared to stabilization ponds without attached growth. Scoullos et al. (2007) compared the trace metal levels obtained in year 2000 and 2004 and found a decreasing trend which may be attributed to the operation of the wastewater treatment plant offering an indication that the levels of trace metal pollution of the marine environment of the gulf are possibly reaching a steady state.

3. Conclusions Wastewater treatment aims at to generate an effluent and a solidified material known as sludge which is appropriate for discharge or reuse back into the surroundings. Inefficient removal of impurities can pose a serious health hazard. However, reclaim must be secure to stay away from damaging wellbeing of the public and the environment. Efficient and proper wastewater purification processes thus can reduce the health related concerns associated with wastewater recycling. The Copyright © 2013 by Modern Scientific Press Company, Florida, USA


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performance efficiency of treatment plant depends on proper design and construction and also on good operation and maintenance.

References Abdel-Hafez, A. I. I., and El-Sharouny, H. M. M. (1987). Seasonal fluctuations of fungi, in Egyptian soil receiving city sewage effluents. Cryptog. M. Mycol., 8: 235-249 Abdel-Hafez, A. I. I., and El-Sharouny, H. M. M. (1990). The occurrence of keratinophilic fungi in sewage sludge from Egypt. J. Basic Microbiol., 30: 73-79. Abdel-Mallek, A. Y., Moharram, A. M., and Bagy, M. M. K. (1988). Effect of soil treatment with sewage and sludge on fungal populations. J. Basic Microbiol., 28: 565-570. Abis, K. L. (2002). The Performance of Facultative Waste Stabilization Ponds in the UK. Ph.D. thesis, University of Leeds, UK. Ahalya, N., Kanamadi, R. D., and Ramachandra, T. V. (2005). Biosorption of chromium(VI) from aqueous solutions by the husk of Bengal gram (Cicer arientinum). Electronic J. Biotechnol., 8(3): 2-8. Ahn, I. S., Kim, M. W., La, H. J., Choi, K. M., and Kwon, J. C. (2003). Bacterial community composition of activated sludge relative to type and efficiency of municipal wastewater treatment plants. J. Microbiol. Biotechnol., 13: 15-21. Akpor, O. B., and Muchie, M. (2011). Environmental and public health implications of wastewater quality. Afric. J. Biotechnol., 10: 2379-2387. Aleksandrowies, J., and Smyk, B. (1973). The association of neoplastic diseases and Mycotoxins in the environment. Texas Rep. Biol. Med., 31: 715-721. Alexander, G. C., and Stevens, R. J. (1976). Per capita phosphorus loading from domestic sewage. Water Res., 10: 257-769. Al-Zubeiry, A. H. S. (2005). Microflora inhabiting raw sewage, secondary effluent and dewatered sludge in Ibb, yemen republic. Ass. Univ. Bull. Environ. Res., 8: 1-6. Antunes, S., Dionisio, L., Silva, M. C. (2007). Proceedings of the 3rd IASME/WSEAS International Conference on Energy, Environment, Ecosystems and Sustainable Development, Agios Nikolaos, Greece, July 24-26. Arceivala, S. J. (1981). Wastewater Treatment and Disposal, Pollution Engineering and Technology. Marcel Dekker Inc., New York. Arridge, H., Oragui, J. I., Pearson, H. W., Mara, D. D., and Silva, S. A. (1995). Vibrio cholerae and Salmonella removal compared with the die-off of faecal indicator organisms in waste stabilization ponds in northeast Brazil. Water Sci. Technol., 31: 249-265. Copyright © 2013 by Modern Scientific Press Company, Florida, USA


133

Awuah, E., and Abrokwa, K. A. (2001). Performance evaluation of the UASB sewage treatment plant at James Town (Mudor), Accra. Access to sanitation and safe water, global partnerships and local actions. 33rd WEDC International Conference, Accra, Ghana. Awuah, E., and Abrokwah, K. A. (2008). Performance evaluation of the UASB treatment plant at James Town (Mudor), Accra. A paper presented at the 33rd WEDC Conference, Accra, Ghana. Awuah, E., Oppong-Pzrah, M., Lubberding, H. J., and Gijzen, H. J. (2004). Comparative performance studies of water lettuce, duckweed and algal based stabilization ponds using low strength sewage. J. Toxicol. Environ. Health, 67: 1727-1739. Bahlaoui, M. A., Baleux, B., and Troussellier, M. (1997). Dynamics of pollution-indicator and pathogenic bacteria in high-rate oxidation wastewater treatment ponds. Water Res., 31: 630-638. Balakrishnan, S., and Eckenfelder, W. W. (1970). Nitrogen removal by modified activated sludge processes. J. San Enging Div., 96: 501-512. Banu, J. R., Kaliappan, S., and Yeom, I. T. (2007). Treatment of domestic wastewater using upflow anaerobic sludge blanket reactor. Int. J. Environ. Sci. Tech., 4: 363-370. Bataineh, F., Najjar, M., and Malkawi, S. (2002). Wastewater reuse, in water demand management forum, Amman, Jordan. Bausum, H. T., Schaub, S. A., Kenyon, K. F., and Small, M. J. (1982). Comparison of coliphage and bacterial aerosols spray irrigation site. Appl. Environ. Microbiol., 43: 28-38. Biedunkiewicz, A., and Ozimek, T. (2009). Qualitative and quantitative changes of potentially pathogenic fungi in a hydrophyte wastewater treatment plant. Polish J. Environ. Study, 18: 161-166. Bitton, G. (2005). Wastewater Microbiology, 3rd ed. John Wiley and Sons, Chichester. Bond, P. L., Erhart, R., Wagner, M., Keller, J., and Blackal, L. L. (1999). Identification of some of the major groups of bacteria in efficient and nonefficient biological phosphorus removal activated sludge systems. Appl. Environ. Microbiol., 65: 4077-4084. Borah, S., Brauah, A. M., Das, A. K., and Borah, J. (2009). Determination of mineral content in commonly consumed leafy vegetables. Food Anal. Methods, 2: 226-230. Bouwer, H. (1978). Groundwater Hydrology. McGraw-Hill Company, New York, 480 pp. Broome, J. M., Morris, P. M., and Nanthambwe, J. G. (2003). Hybrid treatment systems anaerobic ponds and trickling filters in Zimbabwe. Water Sci. Technol., 48: 349-356. Bunse, T., and Merk, H. (1992). Mycological aspects of inhalative mould allergies. Mycoses, 35: 6166. Chitnis, V., Chitnis, S., Vaidya, K., Ravikant, S., Patil, S., and Chitnis, D. S. (2004). Bacterial population changes in hospital effluent treatment plant in central India. Water Res., 38: 441-447. Collivignarelli, C., Urbini, G., Farneti, A., Bassetti, A., and Barbaresi, U. (1990). Anaerobic-aerobic



134

treatment of municipal wastewater with full scale up-flow anaerobic sludge blanket and attached biofilm reactors. Water Sci. Technol., 22: 475-482. Colmenarejo, M. F., Rubio, A., Sanchez, E., Vicente, J., Gracia, M. G., and Bojra, R. (2006). Evaluation of municipal wastewater treatment plants with different technologies at Las-Rozas, Madrid (Spain). J. Environ. Manag., 81: 339-404. Cooke, W. B., and Busch, K. A. (1957). Activity of cellulose decomposing fungi isolated from sewage polluted water. Sewage Ind. Wastes, 29: 210-217. Cooke, W. B., and Busch, K. A. (1958). Activity of cellulose decomposing fungi isolated from sewage polluted water. Sewage Ind. Wastes, 29: 210-217. Cooke, W. B. (1970). Fungi in the Lebanon sewage treatment plants and in Turtle Creek, Warren co., Ohio. Mycopath. Mycol. Appl., 42: 89-111. CPHEEO (Central Public Health and Environmental Engineering Organization). (1993). Manual on Sewerage and Sewage Treatment, 2nd ed. Ministry of Urban Development, New Delhi. Craun, G. F. (1991). Cause of waterborne outbreaks in the United States. Water Sci. Technol., 24(2): 17-20. Curtis, T. P., Mara, D. D., and Silva, S. A. (1992). The Effect of Sunlight on faecal coliforms in ponds, implications for research and design. Water Sci. Technol., 26: 1729-1738. Dakers, J. L., and Cockburn, A. G. (1990). Rising the standard of operation of small sewage works. Water Sci. Technol., 22: 261-266. Daniel, M. H. B., Montebelo, A. A., Bernardes, M. C., Ometto, J. P. H. B., De camargo, P. B., Krusche, A. V., Ballester, M. V., Victoria, R. L., and Martinelli, L. A. (2001). Effects of urban sewage on dissolved oxygen, dissolved inorganic and organic carbon, and electrical conductivity of small streams along a gradient of urbanization in the piracicaba river basin. Water Air Soil Pollut., 136: 189-206. Davies-Colley, R. J., Donnison, A. M., Speed, D. J., Ross, C. M., and Nagels, J. W. (1999). Inactivation of faecal indicator microorganisms in waste stabilization ponds, interactions of environmental factors with sunlight. Water Res., 33: 1220-1230. De Hoog, G. S., Guarro, J., Figueras, M. J., and Gene, J. (2000). Atlas of Clinical Fungi, 2nd ed. Centraalbureau voor Schimmelcultures, Utrecht, The Netherlands and Universitat Rovira I Virgili, Reus, Spain. Der Steen, P. V., Brenner, A., Shabtai, Y., and Oron, G. (2000). The effect of environmental conditions on faecal coliform decay in post-treatment of UASB reactor effluent. Water Sci. Technol., 42: 111-118. de Zutter, L., and van Hoof, J. (1984). Occurrence of salmonella in a chemical wastewater treatment



135

plant. Zentralbl Bakteriol Mikrobiol Hyg. B, 179: 440-448. DFID. (1999). A simple methodology for water quality monitoring. In: HR report OD 142 (KAR Project R6662), Pearce, G. R., Chaudhry, M. R., and Ghulum, S. (eds.), Published by the Department for International Development, Wallingford. Dichtl, N., Engelhardt, N., Firk, W., and Koppetsch, J. (1994). Conventional and unconventional integration of trickling filters in a process for biological nutrient removal. Water Sci. Tech., 29(12): 81-88. Doughari, J. H., Dodo, J. S., and Mbuh, F. A. (2007). Impact of effluent from Gudu district sewage treatment Planton Gudu stream in Abuja, Nigeria. J. Appl. Sci. Environ. Manag., 11: 79-83. Downing, A. L., Painter, H. A., and Knowles, G. (1964). Nitrification in the activated sludge process. J. Proc. Inst. Sew. Purif., 63: 130-158. Draaijer, H., Schaapman, J. E., and Khan, A. (1992). Performance of the 5 MLD UASB reactor for sewage treatment at Kanpur India. Water Sci. Tech., 25(7): 123-133. Drury, D. D., Shepherd, W., and Narayanan, B. (2006). A Holistic Approach, WE and T 18(3) March. Dudley, D. J., Guentzel, M. N., Ibarra, M. J., Moore, B. E., and Sagik, B. P. (1980). Enumeration of potentially pathogenic bacteria from sewage sludges. Appl. Environ. Microbiol., 39: 118-126. Dulkadiroglie, H., Cokgor, E. U., Artan, N., and Orhon, D. (2005). The effects of temperature and sludge age on COD removal and nitrification in a moving bed sequencing batch biofilm reactor. Water Sci. Technol., 51: 95-103. Dungeni, M., van der Merwe, R. R., and Momba, M. N. B. (2010). Abundance of pathogenic bacteria and viral indicators in chlorinated effluents produced by four wastewater treatment plants in the Gauteng Province, South Africa. Water SA, 36: 607-613. Dunlop, S. G., and Wang. W. L. (1961). Studies on the use of sewage effluent for irrigation of truckcrops. J. Milk Food Technol., 24: 44-47. Elmitwalli, T. A., and Otterpohl, R. (2007). Anaerobic biodegradability and treatment of grey water in upflow anaerobic sludge blanket (UASB) reactor. Water Res., 41: 1379-1387. Emparanza-Knorr, A., and Torrella, F. (1995). Microbiological performance and salmonella dynamics in a wastewater depuration pond system of southeastern Spain. Water Sci. Technol., 31: 239-248. Epstein, L., Kimberly, D., and Safir, G. (1982). Plant diseases in an old field ecosystem irrigated with municipal wastewater. J. Environ. Qual., 11: 65-69. Fatoki, S. O., Muyima, N. Y. O., and Lujiza, N. (2001). Situation analysis of water quality in the Umtata River catchment. Water SA, 27: 467-474. Feachem, R. G., Bradly, D. G., Garelic, H., and Mara, D. D. (1983). Sanitation and disease, Health Aspect of Excreta and Wastewater Management. John Wiley, Chichester.



136

Firfilionis, G., Paraskevopoulou, V., Vilioti, G., and Dassenakis,M. (2004). The removal of trace metals at the wastewater treatment plant of Psyttalia. Mediterranean Marine Sci., 5: 71-81. Fleisher, J., Schlafmann, K., Otchwemah, R., and Botzenhart, K. (2000). Elimination of enteroviruses, F-specific coliphages, somatic coliphages and E. coli in four sewage treatment plants of southern Germany. J. Water Supply Res. Technol., 49: 127-138. Freid, J. J. (1991).

Nitrates and their control in the EEC aquatic environment. In: Nitrate

Contamination, Exposure, Consequences and Control, Borgadi, I., and Kuzelka, D. (eds.), NATO ASI Series G30, Ecological Sciences. Springer-Verlag, Berlin. Geldereich, E. E. (1990). Microbiology quality of source waters for water supply. In: Drinking Water Microbiology, Progress and Recent Development, McFeters, G. A. (ed.). Springer Verlag, New York, pp. 3-31. Gerba, C. P. (1999). Indicator microorganisms. In: Environmental Microbiology, Maier, R. M., Pepper, I. L., and Gerba, C. P. (eds.). Academic Press, San Diego, CA, pp. 491-503. Gnirss, R., Lesjean, B., and Buisson, H. (2006). Enhanced biological phosphorus removal with postdenitrification in membrane bioreactor. WERF Workshop BNR, How Low Can We Go and What Prevents Us from Going Lower? Held at DCWASA Headquarters, Washington DC. Gray, N. F. (1982). A key to the major slim-forming organisms of sewage fungus. J. Life Sci. R Dublin Sco., 4: 97-112. Gray, N. F. (2004). Biology of Waste Water Treatment, 2nd ed. Imperial College Press, London. Groterud, O., and Smoczynski, L. (1991). Phosphorus removal and chlorinating of wastewaters by electrolysis. Vatten Vol., 47: 273-277. Hammer, M. J. (1996). Water and Wastewater Technology, 3rd ed., Prentice–Hall Inc., New York. Hamouri, B. E., Khallayoune, K., Bouzouba, K., Rhallabi, N., and Chalabi, M. (1994). High rate algal pond performances in faecal coliforms and helminth egg removals. Water Res., 28: 171-174. Haruna, A., Uzairu, A., and Harrison, G. F. S. (2009). Determination of levels of trace metals in sewage vegetation and sludge in Zaria city, Nigeria. Elect. J. Environ. Agric. Food Chem., 8: 500511. Hickey, J. L. S., and Reist, P. C. (1975). Health significance of air-borne microorganisms from Wastewater treatment processes. J. Water Pollut. Control Fed., 47: 2741-2757. Hodgson, I. O. (2003). Diurnal variation of quality of sewage and effluent in waste stabilization and treatment ponds at Akosombo. JAST, 8: 5-61. Hodgson, I. O. (2007). Performance of the Akosombo waste stabilization ponds in Ghana. Ghana J. Sci., 47: 35-44. Horan, N. J., Fletcher, L., Betmal, S. M., Wilks, S. M., and Keevil, C. W. (2004). Die-off of enteric



137

bacterial pathogens during mesophilic anaerobic digestion. Water Res., 38: 1113-1120. Howard, I., Espigares, E., Lardelli, P., Martín, J. L., and Espigares, M. (2004). Evaluation of microbiological and physicochemical indicators for wastewater treatment. Environ. Toxicol., 19: 241-249. Igbinosa, E. O., and Okoh, A. I. (2009). Impact of discharge wastewater effluents on the physicochemical qualities of a receiving watershed in a typical rural community. Int. J. Environ. Sci. Tech., 6: 175-182. Ismail, M. A., and Abdel-Sater, M. A. (1994). Mycoflora inhabiting water closet environments. Mycoses, 37: 53-57. Jamwal, P., Mittal, A. K., and Mouchel, J. M. (2009). Efficiency evaluation of sewage treatment plants with different technologies in Delhi (India). Environ. Monit. Assess., 153: 293-305. Jeon, C. O., Woo, S. H., and Park, J. M. (2003). Microbial communitie of activated sludge performing enhanced biological phosphorus removal in a sequencing batch reactor supplied with glucose. J. Microbiol. Biotechnol., 13: 385-393. Joko, I. (1984). Phosphorus removal from wastewater by the crystallization method. Water Sci. Tech., 17: 121-132. Joseph, J. M., and Shay, D. E. (1952). The viability of Escherichia coli in acid mine waters. Am. J. Public Health, 42: 795-800. Kacprzak, M., Warchol, M., and Widawska, U. (2003). Microfungal species composition in raw and treated wastewaters from selected wastewater treatment plant. Environ. Eng. Stud., 28: 167-173. Kacprzak, M., Neczaj, E., and Okoniewska, E. (2005). The comparative mycological analysis of wastewater and sewage sludges from selected wastewater treatment plants. The Conference on Desalination and the Environment, Santa Margherita, Italy, 22-26 May. Kaneko, S., and Nakajima, K. (1988). Phosphorus removal by crystallization using a granulated activated magnesia clinker. J. Water Poll. Contr. Fed., 60: 1239-1244. Kantachote, D., Dangtago, K., and Siriwong, C. (2009). Treatment efficiency in wastewater treatment plant of Hat Yai Municipality by quantitative removal of microbial indicators. Songklanakarin J. Sci. Technol., 31: 567-576. Kapur, A., Kansal, A., Prasad, R. K., and Gupta, S. (1999). Performance evaluation of sewage treatment plant and sludge bio-methanation. Indian J. Environ. Protect., 19: 96-100. Karthikeyan, C., and Sabarathinam, P. L. (2002). Biodegradation of cassava starch wastewater using UASB Reactor. J. Ind. Poll. Contr., 18: 33-40. Kassab, G., Halalsheh, M., Klapwijk, A., Fayyad, M., and van Lier, J. B. (2010). Sequential anaerobic–aerobic treatment for domestic wastewater: A review. Bioresour. Technol., 101: 3299-



138

3310. Kay, D., Crowther, J., Stapleton, C. M., Wyer, M. D., Fewtrell, L., Edwards, A., Francis, C. A., McDonald, A.T., Watkins, J., and Wilkinson, J. (2008). Faecal indicator organism concentrations in sewage and treated effluents. Water Res., 42: 442-454. Kayser, R., Boll, R., and Muller H. E. (1987). Quantitative determinations of the elimination of salmonellae by biological treatment of wastewater. Zentralbl Bakteriol Mikrobiol Hyg. B, 184: 195205. Kempster, P. L., van Vliet, H. R., and Kuhn, A. (1997). The need for guidelines to bridge the gap between ideal drinking water quality and that quality which is practically achievable and acceptable. Water SA, 23: 163-167. Khalil, N., Sinha, R., Raghav, A. K., and Mittal, A. K. (2008). UASB technology for sewage treatment in India: experience, economic evaluation and its potential in other developing countries. Twelfth International Water Technology Conference, IWTC12, Alexandria, Egypt. Khatri, S. K., and Dhankar, R. (2003) Evaluation of sewage wastewater as a source of irrigation and manure of Rohtak city of Haryana. Environmedia, 22: 549-552. Kim, Y., Mikawa, K., Saito, T., Tanaka, K., and Emori, H. (1997). Development of novel anaerobic/aerobic filter process for nitrogen removal using immobilized nitrifiers pellets. Water Sci. Technol., 36(12): 151-158. Knowles, R. (1982). Denitrification. Microbiol. Rev. 46: 43-70. Koivunen, J., Siitonen, A., and Heinonen-Tanski, H. (2003). Elimination of enteric bacteria in biological-chemical wastewater treatment and tertiary filtration units. Water Res., 37: 690-698. Kolwitz, R. (1901). Biologie von Leptomitus lacteus. Ber Deut. Botan. Ges., 19: 288-291. Kowal, N. E., Pahren, H. R., and Akin, E. W. (1980). Microbiological health effects associated with the use of municipal Wastewater for irrigation. International Conference on Cooperative Research Need for the Renovation and reuse of Municipal Wastewater for Agriculture, Mexico, D.F., pp. 150. Krogulska, B., and Mycielski, R. (1984). Bacterial microflora participating in the removal of nitrogen from industrial wastewaters by nitrification and denitrifaction. Acta Microbiol. Pol., 33: 67-76. Kumar, P. R., Pinto, L. B., and Somashekar, R. K. (2010). Assessment of the efficiency of sewage treatment plants: A comparative study between nagasandra and mailasandra sewage treatment plants. Kathmandu Univ. J. Sci. Eng. Technol., 6: 115-125. Kumar, K. R., Suman, M., and Archana, S. (2012). Water quality assessment of raw sewage and final treated water with special reference to Waste Water Treatment Plant Bhopal, MP, India. Res. J. Recent Sci., 1: 185-190.



139

Larkin, P. E., Tierney, J. T., Lovett, J., Van Donsel, D., and Francis, G. (1978). Land application of sewage wastes, potential for contamination of foodstuffs and agricultural soils by viruses bacterial pathogens and parasites. In: State of Knowledge in Land Treatment of Wastewater, pp. 215-223. Lee, S. Y., Kim, H. G., Park, J. B., and Park, Y. K . (2005). New nirS-harboring denitrifying bacteria isolated from activated sludge and their denitrifying functions in various cultures. J. Microbiol. Biotechnol., 15: 14-21. Lema, J. M., and Omil, F. (2001). Anaerobic treatment, a key technology for sustainable management of wastes in Europe. Water Sci. Technol., 44: 133-140. Liberti, L. (1982). Ion exchange advanced treatment to remove nutrients from sewage. Stud. Environ. Sci., 19: 225-238. Lim, Y. W., Lee, S. E., Kim, S. B., Yong, H. Y., Yeon, S. H., Park, Y. K., Jeong, D. W., and Park, J. S. (2005). Diversity of denitrifying bacteria isolated from Daejeon Sewage Treatment Plant. J. Microbiol., 43: 383-390. Lloyd, R. (1992). Pollution and Freshwater Fish. Blackwell Scientific Publications Ltd., pp. 3-75. Lucena, F., Duran, A. E., Moron, A., Calderon, E., Campos, C., Gantzer, C., Skraber, S., and Jofre, J. (2004). Reduction of bacterial indicators and bacteriophages infecting faecal bacteria in primary and secondary wastewater treatments. J. Appl. Microbiol., 97: 1069-1076. Luostarinen, S., Luste, S., Valentin, L., and Rintala, J. (2006). Nitrogen removal from on site treated anaerobic effluents using intermittently aerated moving bed biofilm reactors at low temperatures. Water Res., 40: 1607-1615. Machdar, I., Harada, H., Ohashi, A., Sekiguchi, Y., Okui, H., and Ueki, K. (1997). A novel and costeffective sewage treatment system consisting of UASB pre-treatment and post-treatment units for developing countries. Water Sci. Technol., 36: 189-197. Marson, H. W. (1967). Electrolytic sewage treatment: the modern process. Water Poll. Control, 12: 109-119. Maruthi, Y. A., Hossain, K., Priya, D. H., and Tejaswi, B. (2012). Prevalence of Keratinophilic fungi from sewage sludge at some wastewater out lets along the coast of Visakhapatnam: A case study. Adv. Appl. Sci. Res., 3: 605-610. Maynard, H. E., Ouki, S. K., and Williams, S. C. (1999). Tertiary lagoons: A review of removal mechanisms and performance. Water Res., 33: 1-13. Mba, D., Bannister, R. H., and Findlay, G. E. (1999). Mechanical redesign of the rotating biological contactor. Water Res., 33: 3679-3688. McCullough, C. D., Lund, M. A., and May, J. M. (2008). Field-scale demonstration of the potential for sewage to remediate acidic mine waters. Mine Water Environ., 27: 31-39.



140

McGhee, T. (1991). Water Supply and Sewerage, 6th ed. McGraw-Hill, New York, USA. Metcalf, A., and Eddy, I. (1991). Wastewater Engineering, Treatment, Disposal, Reuse, 3rd ed. McGraw-Hill, New York, USA. Metcalf, A., and Eddy, I. (2003). Wastewater Engineering - Treatment, Disposal and Reuse, 4th ed. Tata McGraw Hill Publishing Co. Ltd., New Delhi, India. Misrepasi, A., Honary, H. R., Mesdaghinia, A. H., Vahid, H., and Karyb, H. (2006). Performance evaluation of UASB reactor in treating stillage wastewater. Iran J. Environ. Health Sci., 3: 79-84. Momba, M. N. B., Osode, A. N., and Sibewu, M. (2006). The impact of inadequate wastewater treatment on the receiving water bodies – case study, Buffalo City and Nkokonbe Municipalities of the Eastern Cape Province. Water SA, 32: 687-692. Morrison, G. O., Fatoki, O. S., and Ekberg, A. (2001). Assessment of the impact of point source pollution from the Keiskammahoek sewage treatment plant on the Keiskamma river. Water SA, 27: 475-480. Moshe, M., Betzer, N., and Kott, Y. (1972). Effect of industrial wastes on oxidation pond performance. Water Res., 6: 1165-1171. Moura, A., Tacao, M., Henriques, I., Dias, J., Ferreira, P., and Correia, A. (2007). Characterization of bacterial diversity in two aerated lagoons of a wastewater treatment plant using PCR-DGGE analysis. Microbiol. Res., 164: 560-569. Mulkerrins, D., Dobson, A. D. W., and Colleran, E. (2003). Parameters affecting biological phosphate removal from wastewaters. Environ. Int., 30: 249-260. Nageshwara Rao, V. V., and Shurti, D. (2002). Performance of sewage treatment plants in Hyderabad. Environmedia, 21: 191-193. Nandy, T., and Kaul, S. N. (1994). Wastewater management for tapioca based sago industry. Indian J. Environ. Prot., 14: 721-728. Neethling, J. B., and Gu, A. (2006). Chemical phosphorus removal constraints-Introduction. Session P2 in Water Environment Research Foundation. Nieuwstad, T. J., Mulder, E. P., Havelaar, A. H., and van Olphen, M. (1988). Elimination of microorganisms from wastewater by tertiary precipitation and simultaneous precipitation followed by filtration. Water Res., 22: 1389-1397. Niewolak, S. (1974). Distribution of microorganisms in the waters of the Kortowskie Lake. Pol. Arch. Hydrobiol., 21: 315-321. Nkegbe, E., Emongor, V., and Koorapetsi, I. (2005). Assessment of effluent quality at Glen Wastewater Treatment Plant. J. Appl. Sci., 5: 647-650. Nuhoglu, A., Yildiz, E., Keskinler, B., and Karpuzcu, M. (2004). Wastewater characterization and



141

performance upgrading of a domestic wastewater treatment plant, the Erzincan case. Int. J. Environ. Pollut., 21: 440- 456. OECD. (1982). Eutrophication of Waters, Monitoring, Assessment and Control. Technical Report, Organization for Economic Cooperation and Development, Paris. Oliver, B. G., and Cosgrove, E. G. (1974). The efficiency of heavy metal removal by a conventional activated sludge treatment plant. Water Res., 8: 869-874. Omura, T., Onuma, M., Aizawa, J., Umita, T., and Yagi, T. (1989). Removal efficiencies of indicator micro-organisms in sewage treatment plants. Water Sci. Technol., 21(3): 119-124. Onstott, E. I., Gregory, W. S., Thode, E. F., and Holman, K. L. (1973). Electroprecipitation of phosphate from sewage. J. Environ. Eng. Division, ASCE, 199: 897-907. Pandit, A. K., and Kumar, R. (2008). Impact of effluents on phytoplankton dynamics in Dal Lake of Kashmir Himalaya. J. Himalayan Ecol. Sus. Dev., 3: 33-34. Pearson, I., and Idema, G. (1998). CSIR Division of Water, Environment and Forestry Technology, Pretoria. WRC Report No 649/1/98. Water Research Commission, Pretoria, South Africa, pp. 1-17. Pehlivanoglu Mantas, E., and Sedlak, D. L. (2006). Wastewater derived dissolved organic nitrogen, analytical methods, characterization, and effects. Crit. Rev. Environ. Sci. Technol., 36: 261-285. Pitt, J. I. (1994). The current role of Aspergillus and Penicillium in human and animal health. J. Med. Veter. Mycol., 32: 17-32. Polprasert, C., and Charupraheep, K. (1989). Heavy metal removal in attached growth waste stabilization ponds. Water Res., 23: 625-631. Popp, L. (1973). Elimination of salmonellae by biological treatment of wastewater. Zentralbl Bakteriol Mikrobiol Hyg. B, 157: 184-195. Raco-Rands, V. E. (1997). Characteristics of effluents from large municipal wastewater facilities. In: Southern California Coastal Water Research Project Annual Report, Weisberg, S. B. (ed.), Westminster, CA, pp.17-31. Radojevic, M., and Bashkin, V. N. (1999). Practical Environmental Analysis, The Royal Society of Chemistry, Cambridge, UK. Rajeb, A. B., Kallali, H., Saidi, H., and Abidi, S. (2011). Physicochemical and microbial characteristics performance in wastewater treated under aerobic reactor. Amer. J. Environ. Sci., 7: 254-262. Rai, P. K. (2010). Microcosm investigation on phytoremediation of Cr using Azolla pinnata. Int. J. Phytoremediation, 12: 96-104. Rai, P. K., and Tripathi, B. D. (2007). Microbial contamination in vegetables due to irrigation with partially treated municipal wastewater in tropical city. Int. J. Environ. Health Res., 17: 389-395.



142

Randall, C. W., Barnard, J. L. and Stensel, H. D. (1992). Design and retrofit of wastewater treatment plants for biological nutrient removal. Technomic. Publ. Lancaster. Rawat, K. P., Sharma, A., and Rao, S. M. (1998). Microbiological and physicochemical analysis of radiation disinfected municipal sewage. Water Res., 32: 737-740. Reardon, R. (2006). Technical introduction of membrane separation processes for low temperature limits. Session P3 in Water Environment Research Foundation, 2006. Rogers, T. O., and Wilson, H. A., (1966). pH as a selecting mechanism of the microbial flora in wastewater-polluted acid mine drainage. J. Water Poll. Control Fed., 38: 990-995. Rosas, I., Baez, A., and Coutino, M. (1984). Bacteriological quality of crops irrigation with wastewater in the xochimilco plots, Mexico City, Mexico. Appl. Environ. Microbiol., 12: 1074-1079. Rouse, J. D., Fuji, T., Sugino, H., Tran, H., and Furukawa, K. (2004). PVA - gel beads as a biomass carrier for anaerobic oxidation of ammonium in a packed bed reactor. Proceeding of the HELE CO'05 Conference, Session 16, Athens, Greece. Rovatti, M., Nicolella, C., Converti, A., Ghigliazza, R. and Felice, R. D. (1995). Phosphorus removal in a fluidized bed biological reactor. Water Res., 29: 2627-2634. Rudolfs, W. (1947). Phosphates in sewage treatment: I. Quantities of phosphates. Sewage Works J., 19: 43-47. Ruiz, I., Soto, M., Veiga, M. C., Ligero, P., and Blazquez, R. (1998). Performance and biomass characterization in a UASB reactor treating domestic wastewater at ambient temperature. Water SA, 24: 121-125. Sadeghpoor, M., Hosseini, B., and Najafpour, G. D. (2009). Assessment of wastewater treatment plant’s performance in amol industrial park. American-Eurasian J. Agric. Environ. Sci., 5: 707-711. Saha, M. L., Alam, A., Khan, M. R., and Hoque, S. (2012). Bacteriological, physical and chemical properties of the Pagla sewage treatment plant’s water. J. Biol. Sci., 21: 1-7. Saleem, M., Bukhari, A. A., and Al Malack, M. H. (2000). Removal efficiencies of indicator microorganisms in the Al-Khobar wastewater treatment plant. Environ. Eng. Sci., 17: 227-232. Samie, A., Obi, C. L., Igumbor, J. O., and Momba, M. N. B. (2009). Focus on 14 sewage treatment plants in the Mpumalanga Province, South Africa in order to gauge the efficiency of wastewater treatment. African J. Biotechnol., 8: 3276-3285. Sammon, N. B., Hrrower, K. M., Fabbro, L. D., and Reed, R. H. (2010). Incidence and distribution of microfungi in municipal water supply system in sub- tropical Australia. Int. J. Environ. Res. Public Health, 7: 1597-1611. Sawyer, C. N. (1944). Biological engineering in sewage treatment. Sewage Works J., 16: 925-935. Sawyer, C. N., and Bradney, L. (1945). Rising of activated sludge in final settling tanks. Sewage



143

Works J., 17: 1191-1196. Scoullos, M., ZeriI, C., Dassenakis, M., and Tsamaki, E. (1986). Experiments on the reversibility of transfer – deposition processes of metal under intermittently anoxic conditions. Rap. Com. Int. Mer. Medit, 3: 122-127. Scoullos, M. J., Sakellari, A., Giannopoulou, K., Paraskevopoulou, V., and Dassenakis, M. (2007). Dissolved and particulate trace metal levels in the Saronikos Gulf, Greece. Desalination, 210: 98109. Seckler, M. M., van Leeuwen, M. L. J., Bruinsma, O. S. L., and Rosmalen, G. M. van. (1996). Phosphate removal in a fluidized bed: II. Process optimization. Water Res., 30: 1589-1596. Seghezzo, L., Zeeman, G., Jules, B., van Liel, H. V., Hamelers, M., and Lettinga, G. (1998). A Review, the anaerobic treatment of sewage in UASB and EGSB reactors. Bioresour. Technol., 65: 175-190. Sharma, R. K., Agarwal, M., and Marshal, F. (2009). Heavy metal contamination of soil and vegetables in suburban areas of Varanasi, India. Ecotoxicol. Environ. Saf., 66: 258-266. Shuval, H. I., Adin, A., Fattal, B., Rawitz, G., and Yekutiel P. (1986). Wastewater irrigation in developing countries, health effects and technical solutions. Technical Paper No. 51, World Bank, Washington DC. Simard, R. E. (1971). Yeasts as an indicator of pollution. Mar. Poll. Bull., 12: 123-128. Simpson, E., and Charles, K. (2000). The health threat posed to surrounding community by effluent discharged from rural hospital sewage treatment plants. Proc. WISA (2000) Conference, Sun City South Africa. 28 May - 1 June. Sin, G., Malisse, K., and Vanrolleghem, P. A. (2003). An integrated sensor for the monitoring of aerobic and anoxic activated sludge activities in biological nitrogen removal plants. Water Sci. Technol., 47: 141-148. Sincero, A. P., and Sincero, G. A. (1996). Environmental Engineering: A Design Approach, 4th ed. Prentice-Hall of India Pvt. Ltd., New Delhi, India. Sotirakou, E., Kladitis, G., Diamantis, N., and Grigoropoulou, H. Ammonia and phosphorus removal in municipal wastewater treatment plant with extended aeration. Global Nest Int. J., 1: 47-53. Sperling, M. V., Freire, V. H., and Chernicharo, C. A. L. (2001). Performance evaluation of a UASBactivated sludge system treating municipal wastewater. Water Sci. Technol., 43(11): 323-328. Storhaug, R. (1990). Performance stability of small biological chemical treatment plants. Water Sci. Technol., 22: 275-282. Strom, P. F. (2006). Phosphorus removal techniques. In: Water Quality Trading, 91st Annual Meeting, NJWEA, Atlantic City, NJ.



144

Sumithra, S., and Narayana, J. (2003). Municipal and industrial waste water characteristics and management in Bhadravati City. In: Aquatic Ecosystems, pp. 419-424. Tabak, H., and Cooke, W. B. (1968). Growth and metabolism of fungi in an atmosphere of nitrogen. Mycologia, 60: 115-140. Tajrishy, M., and Abrishamchi, A. (2005). Integrated approach to water and wastewater management for Tehran, Iran: Water conservation, reuse, and recycling. In: Proceedings of the Iranian-American Workshop, National Academies Press, pp. 217-230. Tandukar, M., Uemura, U., Machdar, I., Ohashi, A., and Harada, H. (2005). A low-cost municipal sewage treatment system with a combination of UASB and the “fourth-generation” downflow hanging sponge reactors. Water Sci. Technol., 52(1-2): 323-329. Tawfik, A., Klapwijk, B., Van Buuren, J., El-Gohary, F., and Lettinga, G. (2004). Physicochemical factors affecting the E. coli removal in a rotating biological contactor (RBC) treating UASB effluent. Water Res., 38: 1081-1088. Tchobanoglous, G. (1979). Wastewater Engineering: Treatment Disposal Reuse, 2nd ed. McGraw Hill, Boston, pp. 56-141 & 829-864. Tchobanoglous, G., Burton, F. L., and Stensel, H. D. (2003). Wastewater Engineering: Treatment Disposal Reuse, 4th ed. McGraw Hill, New York, p. 1819. Teitge, E., Gerhardt, G. G., and Gundermann, K. O. (1986). Quantitative studies of Salmonella at two sewage purification plants in Schleswig–Holstein. Zentralbl Bakteriol Mikrobiol Hyg. B, 182: 12030. Tseng, T. C., Tu, J. C., and Tzean S. S. (1995). Mycoflora and mycotoxins in dry bean (Phaseolus vulgaris) produced in Taiwan and in Ontario, Canada. Botan. Bull. Acad. Sinica, 36: 229-234. Ulfig, K. (2003). Studies of keratinolytic and keratinophilic fungi in sewage sludge by means of a multi-temperature hair baiting method. Polish J. Environ. Stud., 12: 461-466. Ulfig, K. (2005). Effect of sewage sludge alkalization and acidification on keratinolytic and keratinophilic fungi. Polish J. Environ. Stud., 14: 647-653. United Nations Development Programme and World Bank. (1990). Wastewater Reuse for Irrigation in the Mediterranean Region. United Nations Development Programme and World Bank, Washington DC, World Bank. Varughese, B., Dhote, S., Pani, S., and Misra, S. M. (2004). Impact of artificial aeration and ozonization on pathogenic bacteria of a tropical sewage feed lake. Environmedia, 23: 199-203. Velez, H., and Diaz, F. (1985). Onychomycosis due to saprophytic fungi. Mycopthologia, 91: 87-92. Villaescusa-Celaya, J. A., Gutierezgalindo, E. A., and Fores-Munoz, G. (2000). Heavy metals in the fine fraction of coastal sediments from Baja California (Mexico) and California (USA). Environ.



145

Pollut., 108: 453-462. Villioti, G. (1998). Monitoring of physico-chemical parameters, evaluation of the operation and effectiveness of the treatment plant. MSc Thesis. Wadhwani, K., and Srivastava, A. (1985). Some cases of onychomycosis from north India in different working environments. Mycopathologia, 92: 149-155. Wang, K. (1994). Integrated anaerobic and aerobic treatment of sewage. Ph.D. Thesis, Sub-department of Environmental Technology, Wageningen University, The Netherlands. Watson, I. M., Robinson, J. O., Burke, V., and Grace, M. (1985). Invasive of Aeromonas spp. in relation to biotype virulence factors and clinical features. J. Clin. Microbiol., 22: 48-51. Wery, N., Lhoutellier, C., Ducray, F., Delgenes, J. P., and Godon, J. J. (2008). Behaviour of pathogenic and indicator bacteria during urban wastewater treatment and sludge composting, as revealed by quantitative PCR. Water Res., 42: 53-62. Winfrey, B. K., Strosnider, W. H., Nairn, R.W., and Strevett, K. A. (2010). Highly effective reduction of fecal indicator bacteria counts in an ecologically engineered municipal wastewater and acid mine drainage passive co-treatment system. Ecol. Eng., 36: 1620-1626. World Health Organization (WHO) (2006). Guidelines for Drinking-water Quality, 3rd ed., Vol. 1, Recommendations, Geneva, p. 515. Wortman, A. T., Voelz, H., Lantz, R. C., and Bissonette, G. K. (1986). Effect of acid mine water on Escherichia coli, structural damage. Curr. Microbiol., 14: 1-5. WRC (2000). National Eutrophication Monitoring Programme. Implementation Manual. Draft Report, Water Research Commission, Pretoria. Wuhrmann, K. (1962). Nitrogen removal in sewage treatment process. Plenary Session of Wednesday, August, 22, 15th International Congress of Limnology, Madison, Wisc. Yaziz, M. I., and Lloyd, B. J. (1979). The removal of salmonellas in conventional sewage treatment processes. J. Appl. Bacteriol., 46: 131-142. Zeeman, G., and Lettinga, G. (1999). The role of anaerobic digestion of domestic sewage in closing the water and nutrients cycle at community level. Water Sci. Technol., 39(5): 187-194. Zhuang, P., McBridge, M. B., Xia, H., Li, N., and Li, Z. (2009). Health risk from heavy metals via consumption of food crops in the vicinity of Dabaoshan mine, South China. Sci. Total Environ., 407: 1551-1651.


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