Water purification generally means freeing water from any kind of impurity it contains, such as contaminants or micro organisms. Water purification is not a very one-sided process; the purification process contains many steps. The steps that need to be progressed depend on the kind of impurities that are found in the water. This can differ very much for different types of water.
Water purification, or drinking water treatment, is the process of removing contaminants from surface water or groundwater to make it safe and palatable for human consumption. A wide variety of technologies may be used, depending on the raw water source, contaminants present, standards to be met, and available finances.
Over time, ecosystems have developed sophisticated ways to process and store natural waste products such as sediments, nutrients, heavy metals, and bacteria. Water is the primary medium for transporting these materials through most ecosystems. The "water purification" process is accomplished to varying degrees in a variety of ecosystems including streams, wetlands, estuaries, and forests. Wetlands and riparian (streamside) plant communities are particularly efficient at improving water quality. These communities act as buffers that filter and process sediment and debris from floods, waste products from aquatic and terrestrial plants and animals, and, minerals, metals, and microorganisms before they can reach faster moving water such as rivers.
Sources of Drinking Water Water to be used in public or private water supplies can be drawn from a variety of sources. Different sources of raw water demand different treatment methods to render it ft for human consumption.
Deep Groundwater - The water emerging from some deep groundwaters may have fallen as rain many decades or even hundreds of years ago. Soil and rock layers will have naturally filtered the groundwater to a high degree of clarity even before it is pumped to the treatment plant. Such water may emerge as springs, artesian springs, or may be extracted from boreholes or wells. Deep groundwater is generally of very high bacteriological quality but may be rich in dissolved solids especially carbonates and sulphates of calcium and magnesium. Depending on the strata through which the water has flowed , other ions may also be present including chloride, and bi-carbonate and there may be a requirement to reduce the iron or manganese content of this water to make it pleasant for drinking, cooking, and laundry use. Disinfection is also required. Where groundwater recharge is practised, such groundwaters should be graded as being equivalent to lowland surface waters for treatment purposes. Shallow groundwaters - water emerging from shallow groundwaters are usually abstracted from wells or boreholes and the bacteriological quality can be variable depending on the nature of the catchment. A variety of soluble materials may be present including potentially toxic metals such as copper or zinc. In parts of Bangladesh many shallow ground water sources are contaminated with unacceptably high levels of arsenic. Upland lakes and reservoirs - typically located in the headwaters of rivers systems, upland reservoirs are usually sited above any human habitation and may be surrounded by some form of protection zone to restrict the opportunities for contamination. Bacterial and pathogens levels are usually low but some bacteria, protozoa and algae will be present. Where upland are forested or are peaty, humic acids can colour the water brown. Many upland sources have low pH which requires adjustment before the water is put into supply. Rivers , Canals and low-land reservoirs - lowland surface waters will have a significant bacterial load and may also contain algae, suspended solids and a variety of dissolved constituents Water Treatment Methods Screening - A municipal surface water treatment plant must first screen or sieve out large objects such as trash and leaves. The tighter the mesh of the sieve, the smaller the particles must be to pass through. Filtering is not sufficient to completely purify water, but it is often a necessary first step, since such particles can interfere with the more thorough purification methods. Storage- Water from rivers may also be stored in bankside reservoirs for periods between a few days and many months to allow natural biological purification to take place. This is especially important if treatment is to be by slow sand filters The filtered water is then treated to remove any microscopic organisms including protozoa and bacteria. This is generally followed by a disinfection stage to eliminate any residual bacteria and viruses.
For waters that are particulalrly difficult to treat such as from catchments with intensive agriculture, both physical and biological treatment methods may be combined. Flocculation -The water is -treated with small volumes of appropriate chemicals which will form a chemical floc which entraps particles. The most common flocculent chemicals are aluminium salts such as aluminium sulfate which is flocculated by the small addition of lime to raise the pH. Rapid Sand Filters - The use of rapid sand filters is the most common form of physical treatment of water. Passing flocculated water through a sand filter strains out the floc and the particles trapped within it. Where taste and odour may be a problem (organo-leptic impacts), the sand filter may include a layer of activated carbon to remove the taste and odour. Sand filters become clogged with floc after a period in use and they are then backwashed or pressure washed to remove the floc. This backwash water is run into special settling tanks so that the floc can precipitate out and is then disposed of as waste material. In some countries this may be used as a soil conditioner. Slow Sand Filters - Where land and space are available, water may be treated in slow sand filter beds. These rely on biological treatment processes for their action rather than physical filtration. Slow sand filters are carefully constructed using graded layers of sand with the coarsest at the base and the finest at the top. Drains buried at the base of the filter convey treated water away for disinfection.
When a new slow sand filter bed is brought into use, raw water is carefully decanted onto the filter material until a water depth of 1 to 3m is achieved, dependant on the size of the filter bed. The water passing through the filter for the first few hours is recirculated through the filter and not put into supply. Within a few hours, a biological film comprised of bacteria, protozoa, fungi, and algae builds on the surface of the sand. This is the Schmutzedecke layer and it is this layer that removes all the impurities. An effective slow sand filter may remain in service for many weeks or even months if the pre-treatment is well designed and produces an excellent quality of water which physical methods of treatment rarely achieve. Disinfection - The finished water is then disinfected with chlorine gas, chloramine, sodium hypochlorite, chlorine dioxide, ozone, or ultraviolet light, before it is pumped into the distribution system of water mains and storage tanks on its way to consumers. Some plants also pre-chlorinate their raw water influent after the screening phase to reduce the incidence of biological films in the treatment cycle. Water utilities may choose to further boost chlorine levels (termed re-chlorinating) in the distribution system to counteract any pathogens that may occur. Bleach may be used for emergency disinfection at the rate of 2 drops of 5% bleach per liter or quart of clear water according to a treatment table in the following US EPA document Emergency Disinfection (http://www.epa.gov/safewater/faq/emerg.html).
Many environmental and cost considerations affect the siting and design of water purification plants. Groundwater is cheaper to treat, but aquifers once depleted can take thousands of years to recharge. Surface water sources must be carefully monitored for the presence of unusual types or levels of contaminants. The treatment plant itself must be kept secure from vandalism or terrorism and the presence of large quantities of dangerous chemicals mandates special training for workers and emergency personnel. The facility must responsibly dispose of its settled and filtered solids and prevent them from contaminating the treatment components or the source waters. All facilities disinfect finished water, but the exact method of disinfection can be controversial, and the costs and benefits of different methods must be evaluated.
Other Water purification techniques Other popular methods for purifying water, especially for local private supplies are listed below. In some countries some of these methods are also used for large scale municipal supply. Particularly important are Distillation (de-salination of sea-water) and reverse osmosis
Boiling: Water is heated to its boiling point long enough to inactivate or kill microorganisms that normally live in water at room temperature. Near sea level, bring the water to a vigorous rolling boil for at least one minute. At high altitudes (greater than a kilometer or a mile) boil for three minutes. Source: US EPA (http://www.epa.gov/safewater/faq/emerg.html) In areas where the water is "hard", (containing dissolved calcium salts), boiling decomposes the bicarbonate ion, resulting in some (but not all) of the dissolved calcium being precipitated in the form of calcium carbonate. This is the so-called "fur" that builds up on kettle elements etc. in hard water areas. With the exception of calcium, boiling does not remove solutes of higher boiling point than water, and in fact increases their concentration (due to some water being lost as vapour). Carbon filtering: Charcoal, a form of carbon with a high surface area due to its mode of preparation, adsorbs many compounds, including some toxic compounds. Water is passed through activated charcoal to remove such contaminants. This method is most commonly used in household water filters and fish tanks. Household filters for drinking water sometimes also contain silver, trace amounts of silver ions having a bactericidal effect. Distilling: Distillation involves boiling the water to produce water vapour. The water vapour then rises to a cooled surface where it can condense back into a liquid and be collected. Because the solutes are not normally vaporized, they remain in the boiling solution. Even distillation does not completely purify water, because of contaminants with similar boiling points and droplets of unvaporized liquid carried with the steam. However, 99.9% pure water can be obtained by distillation. Reverse osmosis: Mechanical pressure is applied to an impure solution to force pure water through a semi-permeable membrane. The term is reverse osmosis, because normal osmosis would result in pure water moving in the other direction to dilute the impurities. Reverse osmosis is theoretically the most thorough method of large-scale water purification available, although perfect semi-permeable membranes are difficult to create. Ion exchange: Most common ion exchange systems use a zeolite resin bed and simply replace unwanted ions (Ca2+ and Mg2+) with benign (soap friendly) sodium or potassium ions. This is the common water softener. A more rigorous type of ion exchange swaps hydrogen (H+) ions for unwanted cations and hydroxide (OH-) ions for unwanted anions. The result is H+ + OH- --> H2O. This system is recharged with hydrochloric acid and sodium hydroxide. The result is essentially deionized water. Electrodeionization: Water is passed between a positive electrode and a negative electrode. Ion selective membranes allow the positive ions to separate from the water toward the negative electrode and the negative ions toward the positive electrode. High purity de-ionized water results. The water is usually passed through a reverse osmosis unit first to remove nonionic organic contaminants. Portable water purification Portable drinking water systems or chemical additives are available for hiking, camping, and travel in remote areas. Portable pump filters are commercially available with ceramic filters that will filter 5000 to 50,000 liters per cartridge. Some also utilize activated charcoal filtering.
Chemical additives include chlorine dioxide or iodine solutions.
Iodine, in solution, crystallized, or in tablets, is added to water. The iodine kills off many, but not all, of the most common pathogens that may be present in natural fresh water sources such as lakes, rivers, and streams. Carrying iodine for water purification is a lightweight but imperfect solution for those in need of field purification of drinking water.
Solar Disinfection (Sodis): Microbes are destroyed through temperature and UVA radiation, provided by the Sun. Water is placed in a transparent plastic bottle, which is oxygenated by shaking, followed by topping-up. It is placed on tile or metal for six hours in full sun, which raises the temperature and gives an extended dose of solar radiation, killing any microbes that may be present. The combination of the two provides a simple method of disinfection for tropical developing countries.
Water Res, 2004 Nov, 38(19), 4135 - 42
Isolation and characterization of a bacterium capable of removing taste- and odor-causing 2-methylisoborneol from water; Lauderdale CV et al.; 2-Methylisoborneol (MIB), a metabolite of blue-green algae, has been implicated in causing unpalatable drinking water throughout the world . Current non-biological water treatment technologies are ineffective in removing MIB from potable water or are cost-prohibitive, and biological applications may address these problems . We have isolated and characterized a bacterium derived from lake water and capable of aerobically degrading MIB . Light microscopy and transmission electron microscopy revealed that this strain is a spore-forming, flagellated bacterium that is bacilloid in shape, and 16S rRNA phylogenetic analysis determined that it is most closely related to Bacillus fusiformis and Bacillus sphaericus, both members of the Bacillus sphaericus senso lato taxon . While the growth and oxidation potential of this strain was shown to be affected beyond certain MIB concentrations in the mg/l range, it was capable of depleting MIB at mg/l and ng/l concentrations and of removing MIB to concentrations yielding no observed odor.
Water Res, 2004 Nov, 38(19), 4045 - 54
Performance of ion-exchanger grafted textiles for industrial water treatment in dynamic reactors; Lacour S et al.; The performance of a special class of grafted textiles in removing metal cations from industrial wastewaters was examined in continuous reactors . The influence of various parameters on the ion exchange process (reactor geometry, inlet metal ion concentration, solution flow rate, concentration and type of reagent, etc.) was studied over the complete service cycle of the exchanger (saturation, desorption, regeneration, rinsing) . Dynamic ion exchange characteristics were determined and compared with those of resins under identical operating conditions . Higher efficiency of fibrous ion exchangers compared to analogous resins, was shown at all stages of the service cycle . Results were expressed as a function of breakthrough capacity, exchanger utilisation efficiency, volume of solution treated, eluted metal concentration . The use of different reactor geometries showed two of the many possible applications of grafted textiles in water treatment processes.
J Photochem Photobiol B, 2004 Oct 25, 76(1-3), 103 - 6
Sensitised decomposition of microcystin-LR using UV radiation; Gajdek P et al.; UV radiation was applied to degrade cyanobacterial hepatotoxin, microcystin-LR in the presence of phycocyanin as a model natural sensitiser . The concentrations of both the toxin and the pigment used in the experiments were higher by several orders of magnitude than found in the environment . The photoreaction parameters were optimised . The process was found to be of limited use for water treatment due to its low efficacy . Additionally, pronounced UV-induced bleaching of the pigment significantly reducing the photoreaction rates of the toxin was observed for the highest UV radiation intensities applied.
Rev Gastroenterol Peru, 2004 Jul-Sep, 24(3), 223 - 9
{Variation of Helicobacter pylori prevalence and its relation with the level of chlorine in the water at the "Atarjea" plant, Lima, Perú . Period 1985-2002.}; Ramirez R A et al.; OBJECTIVES: Relate the variation in the prevalence of Helicobacter pylori in patients from medium and high socio-economic levels, suffering from chronic active gastritis (CAG) and peptic ulcer, from 1985 to 2002, in Lima, Peru with the content levels of chlorine in the water at the "Atarjea" Water Treatment Plant . MATERIALS AND METHODS: A total of 1,815 patients showing upper gastrointestinal tract symptoms were examined by esophago-gastro-duodenoscopy, excluding those patients who during the past four weeks had been treated with antibiotics, H2 receptor blockers and proton pump inhibitors . The variation of the H . pylori infection prevalence was compared to the content levels of chlorine in the water at the "Atarjea" plant . RESULTS: A total of 1,290 patients with CAG were identified; 178 with duodenal ulcer; 55 with gastric ulcer and 292 with histologically normal gastric mucose (HNGM) . The prevalence of H . pylori in patients with CAG dropped from 83.3% to 58.7% (p<0.001) . In patients with duodenal ulcer, it decreased from 89.5% to 71.9% (p=0.004) and in those with gastric ulcer, from 84.8% to 77.3% (p=0.36) . In patients with HNGM prevalence remained the same (from 2.7% to 0.0%) (p=0.15) . The chlorine content levels at the water of "Atarjea" plant remained relatively stable from 1991 to 2000 . No correlation was found with the prevalence of Helicobacter pylori (p>0.05) . CONCLUSIONS: Between 1985 and 2002, prevalence of Helicobacter pylori with chronic active gastritis (CAG) and/or peptic ulcer in patients from the medium and upper socio-economic strata, diminished . No correlation was found between the chlorine content levels in the water treated at the "Atarjea" plant and the decrease of this prevalence.
Int J Artif Organs, 2004 Aug, 27(8), 723 - 7
The role of improved water quality on inflammatory markers in patients undergoing regular dialysis; Rahmati MA et al.; Hemodialysis utilizes large quantities of water for the preparation of dialysis fluid . Such water meets national standards and international standards but a considerable disparity exists between such standards with respect to microbiological purity . This study collated and retrospectively analyzed the impact of upgrading water systems from that specified in the US standards to those specified in European standards on clinical measures associated with inflammation in four metropolitan dialysis units for two periods . Two periods were compared, three months prior to and six months post upgrading the water treatment systems . The monthly total erythropoietin dosage and intravenous iron supplementation for each patient were also compared over these periods . Variables with significant pre-post differences were assessed using multivariate models to control for confounding factors . The results indicated significant increases in hemoglobin, ferritin and TSat (all p < 0.0001) and albumin (p = 0.0001) were associated with improvement in water quality . Decreases in CRP and creatinine (both p < 0.0001) were also noted . These findings suggest that the current regulations in the United States set the microbiological limits of water and dialysis fluid inappropriately high, and the limits should be revised downwards, since such an approach is reflected in improvement in markers of inflammation.
Environ Res, 2005 Jan, 97(1), 116 - 23
Characterization of NOM in the Han River and evaluation of treatability using UF-NF membrane; Kim MH et al.; Chlorine reacts with the natural organic matter (NOM) that remains in waters and forms halogenated by-products . Some of these products such as trihalomethanes (THMs) and haloacetic acids (HAAs) have been known to cause cancer and other toxic effects to human beings . Disinfection is a process for the inactivation of pathogenic microorganisms and prevention of waterborne diseases . Despite these advantages, disinfection needs to be evaluated and is of concern because of the serious risks to human health . Therefore, this study characterized NOM, which is a disinfection by-product (DBP) precursor, in the water treatment processes from the Han River and evaluated the removal efficiencies of NOM fractions by conventional and advanced processes . The raw water from the Han River contained higher hydrophilic fraction than the hydrophobic fraction . The hydrophilic NOM constituted still 55-70% of NOM in waters after each process . Since the hydrophilic NOM exhibited higher HAAFP than hydrophobic NOM, chlorination of the Han River water produced higher haloacetic acid formation potential (HAAFP) than trihalomethane formation potential (THMFP) . When the fractions of DBPFP are expressed as percentage of total organic halide formation potential (TOXFP), THMFP, HAAFP, and others are 26%, 43%, and 31% of the TOXFP, respectively . UF membrane could replace conventional processes showing a little higher removal efficiency of NOM and DBPFP, but advanced processes will be required to meet future requirements . The ultrafiltration (UF)-nanofiltration (NF) combined membrane process had better removal efficiency of NOM compared to other processes . Therefore, the results of this study suggest that the UF-NF membrane process is one of the best available ways for removing NOM.
Environ Monit Assess, 2004 Nov, 98(1-3), 421 - 31
Evaluating the efficiency of coagulation in the removal of dissolved organic carbon from reservoir water using fluorescence and ultraviolet photometry; Cheng WP et al.; The present study used ultraviolet absorption (UVa) and the florescence intensity (FI) to evaluate the coagulation efficiency for removing dissolved organic carbon (DOC) in the raw water from Min-Ter, Li-Yu-Ten and Yun-Ho-Shen reservoirs in Taiwan . The results indicated that the ratio of DOC removal rate and FI removal rate was maintained at about 1 at various coagulant dosages . However, the ratio of DOC removal rate and UVa removal rate decreased as the coagulant dosage increased . In addition, after coagulation, the use of florescence intensity instead of total organic carbon (TOC) is better than UVa for measuring the DOC removal rate of the raw waters gathered in different months from the three reservoirs . Furthermore, a good linear relationship between florescence intensity and DOC removal rate was observed, and the DOC/FI ratio of raw water from each reservoir can be used to predict the DOC residual concentration after enhanced coagulation . This result shows that fluorescence analysis can be used for on-line and continuous monitoring the effectiveness of organic matter removal in water treatment.
Rev Argent Microbiol, 2004 Apr-Jun, 36(2), 92 - 6
{The action of different coagulants to remove Cryptosporidium during the process of water treatment}; Abramovich B et al.; Cryptosporidium is one of the microorganisms of main concern from the point of view of Public Health, being a priority problem for water treatment plants and water regulatory institutions . Due to its small size and resistance to chlorination, Cryptosporidium removal during the process of drinking water treatment is a hard task . The effectiveness of different coagulants commonly used in the process of removal of oocysts was analyzed . The technique used was the Jar Test . It was found that: 1) coagulants with the addition of polimeric coadjuvants produce over 2 logs of oocyst removal; 2) a low value in turbidity does not necessarily mean optimal parasite removal, and 3) the addition of polyelectrolites to ferric chloride diminishes variability, both in final turbidity and Cryptosporidium removal.
Waste Manag Res, 2004 Aug, 22(4), 306 - 22
A historical context of municipal solid waste management in the United States; Louis GE; Municipal solid waste management (MSWM) in the United States is a system comprised of regulatory, administrative, market, technology, and social subcomponents, and can only be understood in the context of its historical evolution . American cities lacked organized public works for street cleaning, refuse collection, water treatment, and human waste removal until the early 1800s . Recurrent epidemics forced efforts to improve public health and the environment . The belief in anticontagionism led to the construction of water treatment and sewerage works during the nineteenth century, by sanitary engineers working for regional public health authorities . This infrastructure was capital intensive and required regional institutions to finance and administer it . By the time attention turned to solid waste management in the 1880s, funding was not available for a regional infrastructure . Thus, solid waste management was established as a local responsibility, centred on nearby municipal dumps . George Waring of New York City organized solid waste management around engineering unit operations; including street sweeping, refuse collection, transportation, resource recovery and disposal . This approach was adopted nationwide, and was managed by City Departments of Sanitation . Innovations such as the introduction of trucks, motorized street sweepers, incineration, and sanitary landfill were developed in the following decades . The Resource Conservation and Recovery Act of 1976 (RCRA), is the defining legislation for MSWM practice in America today . It forced the closure of open dumps nationwide, and required regional planning for MSWM . The closure of municipal dumps caused a 'garbage crisis' in the late 1980s and early 1990s . Private companies assumed an expanded role in MSWM through regional facilities that required the transportation of MSW across state lines . These transboundary movements of MSW created the issue of flow control, in which the US Supreme Court affirmed the protection of garbage under the Commerce Clause of the Constitution . Thus MSWM in America today is largely managed by municipalities, and operated by a relatively small number of private companies . It consists of a mixture of landfill, incineration, recycling, and composting, and is regulated under RCRA, the Clean Air Act and other related federal and state laws.
Water Sci Technol, 2004, 50(3), 207 - 15
New method for measuring potential secondary stickies in deinked pulp filtrates; Sarja T et al.; Secondary stickies refer to sticky material in recycled fiber process streams, which has been dissolved in one part of process, but turned to solid phase due to changes in process conditions . The material that can later form secondary stickies is called potential secondary stickies . A new, fast, and simple method for measuring the amount of potential secondary stickies was developed to measure the purification result in the deinked pulp (DIP) filtrates . The new method, now called potential secondary stickies method, was tested with process waters from a recycled fiber (RCF) plant . The method was found to be reliable . Several chemicals and chemical combinations were tested in laboratory scale and compared as coagulation-flocculation agents in two dissolved air flotations (DAF) used as internal water treatment units at the RCF plant . With potential secondary stickies method, significant differences between the effectiveness of the chemicals were found, whereas no difference was seen in the quality of purified process water with traditional measuring methods . The measurement method was also used in mill during a two-week measuring period . As a conclusion, it can be said that this method can be used to monitor the quality and to predict the changes in DIP process water.
Wei Sheng Yan Jiu, 2004 Jul, 33(4), 413 - 5
{Development and evaluation of a composite structural filter for removal of arsenic in drinking water}; Zhao Y et al.; OBJECTIVE: To develop a composite structural filter and evaluate its performance on-site for removal of high level arsenic in drinking water . METHODS: Composite filters were manufactured using iron loaded carbon powder and superfine PE resin as main components . Test water was prepared by spiking arsenic in raw drinking water . The filter application safety and removal effects on arsenic and other parameters were tested . RESULTS: The composite structural filter made of iron loaded carbon powder and superfine PE resin in equal quantity was safe for drinking water treatment and reached a capacity of 2.56mgAs/g for water with arsenic concentration of 0.4mg/L, and improved water turbidity and chemical oxygen demand apparently . CONCLUSION: The composite filter manufactured using iron loaded carbon powder and superfine PE resin as main components was appropriate for removal of arsenic in rural drinking water with high level of arsenic.
Ground Water, 2004 Sep-Oct, 42(5), 678 - 88
Use of Rhodamine water tracer in the marshland upwelling system; Richardson SD et al.; Rhodamine water tracer (RWT) was used to characterize the migration of waste water within the saline subsurface of a marshland upwelling system (MUS), which is an alternative on-site waste water treatment system for coastal areas . Field tracer studies were performed to investigate the fresh waste water plume movement within the saline ground water . Pore velocities were calculated using first detection times and ranged from 0.68 to 10.7 x 10(-4) cm/sec for the loamy sandy soil matrix present at the site . Use of RWT in the field also allowed determination of main and preferential flowpaths . One- and two-dimensional laboratory experiments were performed using silica sand to investigate the interactions of the organically rich waste water with RWT within the zone surrounding the point of injection (one-dimensional) and the impact of background salinity on plume movement (two-dimensional) . The results from these studies were used to help explain the field data . One-dimensional breakthrough curves revealed retardation factors for the RWT in the waste water mixture of 1.73 to 1.90 . These results were similar to other researchers, indicating little interaction between the waste water and RWT . Variations in pore water salinity (5, 15, 25, and 35 ppt) were found to have a significant effect on pore water velocities of the fresh water plume (two-dimensional), indicating the need to incorporate background salinities into the design process for MUS.
Mutagenesis, 2004 Sep, 19(5), 341 - 7
Genotoxicity and cytotoxicity assessment in lake drinking water produced in a treatment plant; Buschini A et al.; Chemical analyses and short-term mutagenicity bioassays have revealed the presence of genotoxic disinfection by-products in drinking water . In this study, the influence of the different steps of surface water treatment on drinking water mutagen content was evaluated . Four different samples were collected at a full-scale treatment plant: raw lake water (A), water after pre-disinfection with chlorine dioxide and coagulation (B), water after pre-disinfection, coagulation and granular activated carbon filtration (C) and tap water after post-disinfection with chlorine dioxide just before its distribution (D) . Water samples, concentrated by solid phase adsorption on silica C18 columns, were tested in human leukocytes and HepG2 hepatoma cells using the comet assay and in HepG2 cells in the micronuclei test . A significant increase in DNA migration was observed in both cell types after 1 h treatment with filtered and tap water, and, to a lesser extent, chlorine dioxide pre-disinfected water . Similar findings were observed for the induction of "ghost" cells . Overloading of the carbon filter, with a consequent peak release, might explain the high genotoxicity found in water samples C and D . Cell toxicity and DNA damage increases were also detected in metabolically competent HepG2 cells treated with a lower concentration of tap water extract for a longer exposure time (24 h) . None of the water extracts significantly increased micronuclei frequencies. l, h. Our monitoring approach appears to be able to detect contamination related to the different treatment stages before drinking water consumption and the results suggest the importance of improving the technologies for drinking water treatment to prevent human exposure to potential genotoxic compounds.
J Water Health, 2004 Mar, 2(1), 1 - 13
A systematic review of the health outcomes related to household water quality in developing countries; Gundry S et al.; In developing countries, the microbial contamination of household drinking water is implicated in the prevalence of various diseases . This systematic review is concerned with two health outcomes, general diarrhoea and cholera, and their relationship with water quality at point-of-use . Observational studies investigating this relationship are reviewed, as well as studies of home water treatment and storage interventions . For cholera, a clear relationship was found with contaminated water . Home water treatment and storage interventions were also found to reduce cholera . For general diarrhoea, no clear relationship was found with point-of-use water quality, although interventions did significantly reduce diarrhoeal incidence . Reasons for these apparently contradictory results concerning general diarrhoea are discussed and suggestions for further research offered . The policy implications of the findings are also discussed.
J Econ Entomol, 2004 Aug, 97(4), 1378 - 83
Insecticidal properties of a Chenopodium-based botanical; Chiasson H et al.; The emulsifiable concentrate UDA-245 based on an essential oil extract from Chenopodium ambrosioides variety near ambrosioides, a North American herbaceous plant, was compared with commercially available pesticides for their effectiveness to control green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae), western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and greenhouse whitefly, Trialeurodes vaporariorium (Westwood) (Homoptera: Aleyrodidae) . Side effects on the whitefly parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae) also were determined . With green peach aphid, UDA-245 at 0.5% concentration was significantly more effective than the control (water) treatment in a laboratory bioassay and significantly more effective than neem oil and the control treatment and as effective as insecticidal soap in a greenhouse assay . With the western flower thrips, UDA-245 at 0.5% was significantly more effective than neem oil, insecticidal soap and the control treatment in a laboratory bioassay, whereas in a greenhouse assay, UDA-245 at 1.0% was the only treatment that maintained control of the western flower thrips 2 wk after the last treatment period . UDA-245 at 0.5% (laboratory bioassay) was significantly more effective in managing greenhouse whitefly than neem oil, endosulfan, and the control treatment and as effective as insecticidal soap . Insecticidal soap proved to be toxic to the parasitoid E . formosa (71.9% mortality), whereas UDA-245 at 0.5% was not significantly more toxic than the control (11.2 and 4.6% mortality, respectively) . Our results suggest that a greenhouse integrated pest management (IPM) program using a botanical such as UDA-245 could effectively control infestations of major pests present while having a negligible effect on biological control agents.
J Water Health, 2003 Mar, 1(1), 15 - 22
A novel technology to improve drinking water quality: a microbiological evaluation of in-home flocculation and chlorination in rural Guatemala; Rangel JM et al.; An estimated 1 billion persons in low-income countries do not have access to improved drinking water . Chlorine, a useful water treatment agent, is less effective in turbid water, and lacks a visible effect, limiting its acceptability . A product incorporating precipitation, coagulation, flocculation, and chlorination technology (combined product) to reduce microbial, organic and heavy metal contaminants in water was evaluated . The combined product's microbiological efficacy in Guatemalan villagers' households was evaluated . One hundred randomly selected households from four neighboring Guatemalan villages were enrolled . Three groups received the combined product and either the Centers for Disease Control (CDC) water storage vessel, a covered bucket with spigot, or no vessel . One group received chlorine bleach and the CDC water storage vessel, and one group no intervention . Household water samples were collected for 4 weeks and Escherichia coli, chlorine, and turbidity levels were measured . Potable water was defined as having less than one E . coli per 100 ml . Eight (8%) baseline water samples were potable . Follow-up water samples were more likely to be potable than control samples (combined product and traditional vessel 83%; combined product and CDC vessel 92%; combined product and covered bucket with spigot 93%; chlorine and CDC vessel 92%; versus control 5%) . Among combined product users, 98% reported improved water clarity compared with 45% of chlorine bleach users (p < 0.0001) . The combined product technology improved water potability as effectively as chlorine bleach; improved water clarity could motivate more persons to effectively treat their water.
J Water Health, 2003 Jun, 1(2), 91 - 100
Indigenous bacterial spores as indicators of Cryptosporidium inactivation using chlorine dioxide; Verhille S et al.; This objective of this study was to explore the practicality of monitoring naturally occurring organisms to predict drinking water treatment plant performance, in this case for the reduction of Cryptosporidium . Surface and ground water from seven drinking water treatment plants across North America that use chlorine dioxide were surveyed for aerobic and anaerobic bacterial spore concentrations . The concentrations of total spores were usually high enough in both raw and treated water to allow 4- to 5-log reductions to be observed across the treatment train by filtering up to 2 l of sample . These results suggested that naturally occurring treatment-resistant spores could be candidates as indicators of treatment performance . However, to be useful as indicators for Cryptosporidium reduction, the organisms would have to exhibit similar resistances to disinfection (chlorine dioxide in this case) in order to be useful . The inactivation kinetics of seven of the most common species were determined, and all were observed to be considerably more susceptible to chlorine dioxide inactivation than Cryptosporidium as reported in the literature . This study therefore did not identify an appropriate ambient microbial indicator for Cryptosporidium control.
J Water Health, 2003 Jun, 1(2), 73 - 84
Evaluation of a new water treatment for point-of-use household applications to remove microorganisms and arsenic from drinking water; Souter PF et al.; Contamination of drinking water by microorganisms and arsenic represents a major human health hazard in many parts of the world . An estimated 3.4 million deaths a year are attributable to waterborne diseases . Arsenic poisoning from contaminated water sources is causing a major health emergency in some countries such as Bangladesh where 35 to 77 million people are at risk . The World Health Organization (WHO) has recently recognized point-of-use water treatment as an effective means of reducing illness in developing country households . A new point-of-use water treatment system that is based on flocculation, sedimentation and disinfection was evaluated for the removal of bacterial, viral and parasitic pathogens as well as arsenic from drinking water to estimate its potential for use in developing countries . Tests were conducted with United States Environmental Protection Agency (EPA)-model and field- sample waters from developing countries . Samples were seeded with known numbers of organisms, treated with the combined flocculation/disinfection product, and assayed for survivors using standard assay techniques appropriate for the organism . Results indicated that this treatment system reduced the levels from 10(8)/l to undetectable (<1) of 14 types of representative waterborne bacterial pathogens including Salmonella typhi and Vibrio cholerae . No Escherichia coli were detected post-treatment in 320 field water samples collected from five developing countries . In addition, the water treatment system reduced polio and rotavirus titres by greater than 4-log values . Cyrptosporidium parvum and Giardia lamblia inocula were reduced by greater than 3-log values following use of this water treatment system . Arsenic, added to laboratory test waters, was reduced by 99.8%, and naturally occurring arsenic in field samples from highly contaminated Bangladeshi wells was reduced by 99.5% to mean levels of 1.2 microg/l . This water treatment system has demonstrated the potential to provide improved drinking water to households in developing countries by removing microbial and arsenic contaminants.
Water Res, 2004 Nov, 38(18), 3971 - 9
Optimisation and significance of ATP analysis for measuring active biomass in granular activated carbon filters used in water treatment; Magic-Knezev A et al.; A method for determining the concentration of active microbial biomass in granular activated carbon (GAC) filters used in water treatment was developed to facilitate studies on the interactions between adsorption processes and biological activity in such filters . High-energy sonication at a power input of 40 W was applied to GAC samples for the detachment of biomass which was measured as adenosine triphosphate (ATP) . Modelling of biomass removal indicated that a series of six to eight sonication treatments of 2 min each yielded more than 90% of the attached active biomass . The ATP concentrations in 30 different GAC filters at nine treatment plants in The Netherlands ranged from 25 to 5000 ng ATP cm(-3) GAC, with the highest concentrations at long filter run times and pretreatment with ozone . A similar concentration range was observed in nine rapid sand (RS) filters . ATP concentrations correlated significantly (p<0.05) with total direct bacterial cell counts in each of these filter types, but the median value of the ATP content per cell in GAC filters (2.1 x 10(-8) ng ATP/cell) was much lower than in the RS filters (3.6 x 10(-7) ng ATP/cell) . Average biofilm concentrations ranging from 500 to 10(5) pg ATP cm(-2) were calculated assuming spherical shapes for the GAC particles but values were about 20 times lower when the surface of pores >1 microm diameter is included in these calculations . The quantitative biomass analysis with ATP enables direct comparisons with biofilm concentrations reported for spiral wound membranes used in water treatment, for distribution system pipes and other aquatic environments.
Water Res, 2004 Nov, 38(18), 3931 - 9
Detection of enteric viruses, Giardia and Cryptosporidium in two different types of drinking water treatment facilities; Ali MA et al.; In this study, two types of drinking water treatment facilities (two conventional drinking water treatment plants (DWTPs) and two compact units (Cus)) were compared referring to their production capacity . Water samples were collected from three main points: (a) different water treatment steps (b) washings of sand filters and (c) distribution system at different distances from the water treatment plants . Both viruses and protozoa were concentrated from each water sample by adsorption and accumulation on the same nitrocellulose membrane filters (0.45 microm pore size) . Enteroviruses were detected by plaque infectivity assay in BGM cells and HAV, HEV and Norovirus were detected by RT-PCR . Giardia and Cryptosporidium were detected by conventional staining methods and PCR . The results revealed that enterovirus load at the intake ranged between 10-15 PFU/L for the two compact units and between 4.5 and 75 PFU/L for the two conventional DWTPs . The virus load in distribution system of the first type DWTPs at 1 km from the plant was the same as that of the intake . Viruses in the other type of treatment plants CUs at 1, 5 and 7 km, were much reduced . Investigation of raw water sediments of the two DWTPs showed enterovirus counts between 12 and 17.5 PFU/L . Virus count was reduced in sand of filters after washing . Giardia cysts were equally detected by microscopy and PCR in only intake samples of EL-Hawamdia CU (33.3%) and Meet Fares DWTP (50%) . Cryptosporidium oocysts were equally detected by microscopy and PCR in intake samples of Abo EL-Nomros CU (100%), EL-Hawamdia CU (66.7%) and Fowa DWTP (50%) . At Meet Fares DWTP three positive intake samples for Cryptosporidium were detected by PCR, compared with only two positive samples by microscopy. g, e. Giardia cysts and Cryptosporidium oocysts were detected in raw water sediment and sand of filters before washing . Only one sample from Meet Fares DWTP sand of filters after washing was positive for both Giardia and Cryptosporidium . It can be concluded that the poor microbial quality of the water may be due to improper operational skills and management of the various water treatment plants (especially at the two high capacity treatment plants).
J Colloid Interface Sci, 2004 Nov 1, 279(1), 1 - 22
Theorization on ion-exchange equilibria: activity of species in 2-D phases; Tamura H; Ion-exchange reactions are naturally occurring at soil and sediment/water interphases, determining soil fertility and water quality . These ion-exchange reactions with inorganic and organic exchangers are applied to chemical analysis, recovery of useful ions from low-grade ores (potentially from sea water), water purification including the preparation of "ultrapure" water, production of foods and medicines, therapy, and other uses . It is important to theorize about or to model ion-exchange reactions for quantitative explanations of ion-exchange phenomena and for efficient operation of ion-exchange processes . This paper describes the modeling of ion-exchange equilibria for hydroxyl sites on metal oxides and carboxyl sites in resins with monovalent cations (alkali metal ions), a monovalent anion (nitrate ion), and divalent heavy metal ions . The procedure of modeling is as follows: the stoichiometry and material balance equations of the respective ion-exchange reactions were established based on findings here and by others . The equilibrium conditions were given by the Frumkin equation, where the mass-action relation is modified with lateral interactions between species at the interphase . The model equations were fitted to the measured data and model parameter values were determined by nonlinear regression analysis . The formation of bonds between ions and exchanger sites was evaluated by the equilibrium constant and the suppression of bond formation by electrostatic, geometric, and other lateral interactions was evaluated by the interaction constant . It was established that the properties of ions are determined by the valence, size, and hydration state of the ions . Monovalent ions (anions and cations) react with oxide surface hydroxyl and resin carboxyl sites as hydrated ions and form loose ion-site pairs by a weak electrostatic bond (nonspecific adsorption) . However, the lateral interactions are large because of a large polarization of the ion-site pairs . When the monovalent cations are dehydrated to react with carboxyl sites in narrow resin nanopores, the bond formation is difficult because energy for dehydration is necessary . The suppressive lateral interactions here are small because of a small polarization of the dehydrated ion-site pairs that are in direct contact . Divalent heavy metal ions react with oxide hydroxyl sites by replacing their hydrated water molecules and form ion-site pairs in direct strong contact (specific adsorption) . The bond formation becomes easier with increasing charge density of the ions evaluated by the charge/radius ratio, agreeing with the order of these ions to form hydroxo complexes in solution . The suppressive lateral interaction is, however, small for ions with large charge densities, because a strong contact bond reduces the polarization of ion-site pairs by neutralization . The properties of exchangers are functions of the molecular and pore environments around the functional groups . The acid-base nature of oxide surface-hydroxyl groups is determined by the electronegativity of surrounding lattice metal ions, and that of resin carboxyl groups by the electron-repelling effect of adjacent methyl groups . Pores in oxides have diameters sufficient to accommodate hydrated ions, and the suppression is large because of repulsion from ions adsorbed on opposite pore walls (across-pore interaction) . Pores in resins differentiate ions that can access or not access sites on the internal surfaces of the pores . Narrow nanopores with diameters less than those of the hydrated ions require ions to dehydrate before they can enter . The ion-exchange reactivity here is small, as described above for dehydrated monovalent ions . In wide nanopores where hydrated ions can enter, bond formation is easier, but suppression is greater because of a larger polarization of hydrated ion-site pairs and also of the across-pore interaction . Macropores have diameters much larger than those of the hydrated ions and the bond formation is the same as that in wide nanopores, but the suppression is smaller because of the absence oe of the absence of the across-pore interaction . Finally, this paper attempts a formulation of activity coefficients of exchanging sites and adsorbed ion-site pairs and compares the proposed activity coefficients of interphase species with that of solution species given by the Debye-Huckel equation.
J Chromatogr A, 2004 Aug 6, 1045(1-2), 85 - 92
Monitoring of estrogens, pesticides and bisphenol A in natural waters and drinking water treatment plants by solid-phase extraction-liquid chromatography-mass spectrometry; Rodriguez-Mozaz S et al.; A multi-residue analytical method has been developed for the determination of various classes of selected endocrine disruptors . This method allows the simultaneous extraction and quantification of different estrogens (estradiol, estrone, estriol, estradiol-17-glucuronide, estradiol diacetate, estrone-3-sulfate, ethynyl estradiol and diethylstilbestrol), pesticides (atrazine, simazine, desethylatrazine, isoproturon and diuron), and bisphenol A in natural waters . In the method developed, 500 ml of water are preconcentrated on LiChrolut RP-18 cartridges . Further analysis is carried out by liquid chromatography-mass spectrometry (LC-MS) using atmospheric pressure chemical ionisation (APCI) in the positive ion mode for determination of pesticides and electrospray in the negative ionisation mode for determination of estrogens and bisphenol A . Recoveries for most compounds were between 90 and 119%, except for bisphenol A (81%) and diethylstilbestrol (70%), with relative standard deviations below 20% . Limits of detection ranged between 2 and 15 ng/l . The method was used to study the occurrence of the selected pollutants in surface and groundwater used for abstraction of drinking water in a waterworks and to evaluate the removal efficiency of the different water treatments applied . Water samples from the river, the aquifer, and after each treatment stage (sand filtration, ozonation, activated carbon filtration and post-chlorination) were taken monthly from February to August of 2002 . The presence in river water of atrazine, simazine, diuron and bisphenol A were relatively frequent at concentrations usually below 0.1 microg/l . Lower levels, below 0.02 microg/l, were usual for isoproturon . Estrone-3-sulfate and estrone were detected occasionally in the river . Most of the compounds were completely removed during the water treatment, especially after activated carbon filtration.
J Nephrol, 2004 Jul-Aug, 17(4), 565 - 9
Dialysis water treatment systems and monitoring in Italy: results of a national survey; Pizzarelli F et al.; BACKGROUND: The risks connected with dialysis fluid contamination are well established . Epidemiological studies have demonstrated just how difficult it is to obtain permanently satisfactory quality standards . Therefore, dialysis centers must have effective and regular quality control programs, particularly with the growing and widespread use of online convective dialysis treatments . Considering this, we conducted a national survey of water treatment systems and monitoring in Italian dialysis centers . METHODS: Two independent questionnaires were prepared and distributed in 1999 and 2001 . The questions were designed to acquire information on structural and procedural elements . Responses to similar questions from both questionnaires were analyzed together . RESULTS: Responses to questionnaires were received from 148 centers (17% of dialysis centers in Italy) . In accordance with the European Best Practice Guidelines (EBPG) published recently concerning dialysis fluid purity, in the majority of centers (97%) the water treatment system consisted of at least pre-treatment and reverse osmosis (RO) modules . However, only one stage RO module was implemented (71%), there was a water storage tank (65%) and water pipe distribution loop was made of sanitary polyvinyl chloride (85%) . Analysis of procedural elements--the timing and type of disinfection procedures used for the waterline system and monitors, the timing and type of water treatment quality control procedures--revealed a striking variability among centers in terms of the types and frequency of checks performed . CONCLUSIONS: Taking into account the EBPG, this survey revealed both bright and dark spots, calling for a national initiative aimed at defining a standard periodicity of loop disinfection, points in the water pipe line to be tested, and the frequency and type of tests.
J Toxicol Environ Health A, 2004 Oct 22-Nov 26, 67(20-22), 1797 - 803
Disinfection by-products in small Alberta community drinking-water supplies; Charrois J et al.; Complacent attitudes toward drinking-water quality can lead to compromised disinfection practices, as noted in such episodes as Walkerton and North Battleford . The first priority for drinking-water providers must be to ensure microbial safety . However, it is recognized that effective disinfection may not be risk free . Consequently, drinking-water guidelines seek to balance the certain danger posed by microbial pathogens with the potential adverse health hazards that may arise from disinfection by-products (DBPs) . Providers of drinking water in small communities often do not have the means to reduce concentrations of DBPs, compared to utilities in larger municipalities . A significant portion of Alberta's population receives drinking water from smaller scale treatment plants or from private wells . A survey of selected DBPs was conducted in 11 rural Alberta communities, with populations ranging from 60 to 2300 . The objectives were to evaluate source water quality, as measured by total organic carbon, and to measure representative concentrations of trihalomethanes (THMs) and haloacetic acids (HAAs) at a point within each distribution system as well as within each water treatment plant . During the 5-wk study, our data show: (1) averages of THM3 (chloroform, bromodichloromethane, chloro dibromomethane) concentrations often exceed 100 microg/L (Health Canada's running annual average guideline for total THMs); (2) source waters with the highest TOC concentrations (15 mg/L) had the highest average THM3 concentrations (200 microg/L); and (3) poor source water quality may necessitate using alternative disinfection options to ensure compliance with microbial and chemical drinking-water guidelines.
J Toxicol Environ Health A, 2004 Oct 22-Nov 26, 67(20-22), 1779 - 95
Aquatic taste and odor: a primary signal of drinking-water integrity; Watson S; Aquatic taste and odor (T/O) is rarely produced by toxic contaminants or pathogens; nevertheless, it has major negative impacts on the public and the drinking-water industry . Consumers use T/O as a primary measure of drinking water safety, yet this criterion is poorly understood, and its origins and triggers often go untraced . Much surface-water T/O is produced by the increased production of volatile organic compounds (VOCs) by algae . These chemicals can be symptomatic of short-term problems with source, treatment, or distribution systems . At a broader level, they can signify fundamental changes in aquatic ecosystems induced by human activity . T/O varies in chemistry, intensity, and production patterns among different algal taxa, and is often linked with excessive algal growth and/or the invasion of noxious species . Some VOCs may signal the presence of potentially toxic algae and/or other associated water quality issues . Traditionally, T/O has been linked with the widespread eutrophication of many surface waters; however, there has been a recent growth in the number of T/O events reported in oligo-mesotrophic systems, for example, the Glenmore Reservoir (Calgary AB) and the Laurentian Great Lakes . From a management and public perspective, therefore, it is vitally important to monitor T/O, and to continue to work toward a better understanding of the proximal and the ultimate causes-which VOCs and algae species are involved . In the short term, odor events could be anticipated and water treatment optimized . In the long term, this approach would contribute toward more a robust management of this resource through remedial or preventative measures.
J Toxicol Environ Health A, 2004 Oct 22-Nov 26, 67(20-22), 1619 - 42
Rural water safety from the source to the on-farm tap; Corkal D et al.; For those Canadians who live in metropolitan areas, good quality water for domestic use and consumption is readily available, and perhaps taken for granted . However, for over 4 million Canadians who rely on private water supplies, access to water that is safe for consumption and suitable for domestic use is a very real issue . This is also true in the agriculture and agri-food sector . Many of these private water supplies are in rural areas, where water is taken from surface or ground sources . These supplies may be of naturally poor quality, or may have had their quality affected by municipal, industrial, or agricultural activities . Options to protect and enhance the quality of private water supplies include source protection using best management practices (BMPs), source enhancement, and water treatment using innovative small-scale systems . With funding from the Canada-Saskatchewan Agri-Food Innovation Fund, Agriculture and Agri-Food Canada has conducted applied research into effective and affordable BMPs (remote livestock watering, low-drift nozzles for spraying farm chemicals, methods to reduce agro-chemical runoff or leaching, etc.) . Source enhancement strategies were studied using aeration for farm ponds or preventive maintenance procedures for ground water wells . Various water treatment technologies were adapted to the small-scale needs of farms, including coagulation, biological sand and biological carbon filtration, membrane filtration using microfilters, nanofilters or reverse osmosis processes, and disinfection systems using chlorination or ultra violet light . Each research project included a technology transfer component, to ensure that the knowledge gained from the research was available to those that needed the information, and to help decision makers address rural water quality problems.
Bioresour Technol, 2003 Oct, 90(1), 1 - 9
Solids removal in upflow anaerobic reactors, a review; Mahmoud N et al.; This desk study deals with the mechanisms and parameters affecting particles separation from wastewater in mainly upflow anaerobic reactors . Despite the fact that the functioning of upflow anaerobic sludge blanket (UASB) systems depends on both physical parameters and biological processes, the physical parameters have been barely reported in the literature . The reason is that the underlying mechanisms are very complex and depend on various interrelated parameters . In addition, the lack of a serious attempt to gather the entire physical theme into one picture has resulted in just a superficial understanding of this field of science . Better understanding of the interaction and role of these parameters is essential for the development of anaerobic treatment technologies . In this study, the various parameters that might affect the solid liquid separation process by filtration through the sludge bed of a UASB have been elaborated . These parameters have been classified into (1) reactor operational conditions (temperature, organic loading rate, hydraulic retention time and upflow velocity), (2) influent characteristics (influent concentration, influent particle size and influent particle charge) and (3) sludge bed characteristics (particle size distribution, extracellular polymeric substances, and charge) . The overall output of this study includes (1) a literature review, (2) structuring of this field of science, and (3) highlighting fields where research is needed.
J Hazard Mater, 2003 Jun 27, 100(1-3), 163 - 78
Treatment of textile wastewaters by electrocoagulation using iron and aluminum electrodes; Kobya M et al.; Treatment of textile wastewaters by electrocoagulation using iron and of aluminum electrode materials has been investigated in this paper . The effects of relevant wastewater characteristics such as conductivity and pH, and important process variables such as current density and operating time on the chemical oxygen demand (COD) and turbidity removal efficiencies have been explored . Furthermore, the electrode and energy consumptions for each electrode have been calculated . The results show that iron is superior to aluminum as sacrificial electrode material, from COD removal efficiency and energy consumption points.
J Environ Monit, 2003 Jun, 5(3), 384 - 94
Multi-component analysis of polar water pollutants using sequential solid-phase extraction followed by LC-ESI-MS; Loos R et al.; A multi-component screening analysis method for polar to medium-polar water pollutants was developed . Sample clean-up and group separation are performed by sequential solid-phase extraction (SSPE) using automated SPE with C18 and polymeric sorbent materials . Analyses are performed by liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) using a single-quadrupole instrument . More than 90 priority compounds of environmental interest--comprising the most important chemical and substance classes: phenols, carboxylic acids, aromatic sulfonates, aromatic amines, pharmaceuticals, surfactants, dyes, and pesticides--have been chosen for the experiments . The compounds are divided by the SSPE procedure into 3 different polarity classes . The extraction recoveries were determined in the 3 fractions for every single substance, and were for most of the analytes in the range of 50-100% . A mixture of hexane-dichloromethane was used for the elution of nonpolar compounds like alkylphenols from C18 . Methanol and acetone are well suited for the elution of more polar substances . The limits of detection (LODs) were determined for all compounds . Effluents from municipal and industrial wastewater treatment plants (WWTPs) treating waste water from textile industries; and the corresponding receiving waters (rivers and lakes) have been analysed with the developed method . Urban and industrial pollution was observed in rivers and streams in the area north of Milan, Italy . In the water samples different phenols (nitrophenols, bisphenol A, nonylphenol), alkylphenol ethoxylate surfactants, their metabolites with endocrine disrupting potential, aromatic sulfonates, linear alkylbenzenesulfonate surfactants, dyes, pesticides, pharmaceuticals, and a dichlorobenzidine compound were identified.
J Chromatogr A, 2002 Mar 1, 948(1-2), 129 - 38
Preparation and characterization of polyalkene membranes modified with four different ion-exchange groups by radiation-induced graft polymerization; Lee KP et al.; Three different cation-exchange membranes with carboxylic acid, phosphoric acid, and sulfonic acid groups, and one anion-exchange membrane with a triethylamine group were prepared by radiation-induced graft polymerization . The maximum capacities of the carboxylic acid, phosphoric acid, sulfonic acid, and triethylamine groups were 3.0, 2.30, 2.43, and 1.42 mmol/g, respectively . The physico-chemical properties of the polyalkene non-woven fabric membrane with four different ion-exchange groups were examined by thermogravimetric analysis, X-ray photoelectron spectrometry (XPS), and scanning electron microscopy . The prepared ion-exchange membrane was applied to the removal of terephthalic acid in dyeing wastewater.
Water Sci Technol, 2003, 47(9), 173 - 8
Electrochemical pilot scale study for reduction of 2,4-DNT; Doppalapudi R et al.; An electrochemical pilot scale reactor was used to treat simulated munitions wastewater containing 100 mg/L of 2,4-dinitrotoluene (DNT) . Experiments were conducted by using a glassy carbon (zero porosity) coated graphite cylinder as the cathode and a platinum wire as the anode . All experiments were conducted under dissolved oxygen concentration of less than 1.5 mg/L . Initially, simulating batch conditions were conducted to obtain the optimum operating conditions for the reactor . During this batch-mode study, the effects of various parameters such as applied current, electrolyte concentration, and type of electrolyte on the reduction of DNT were evaluated . Results obtained showed that the rates of reduction of DNT increased with an increase in current or concentration of electrolyte . Based on the results obtained from the batch simulation experiments, continuous flow experiments were conducted at three different currents . The ionic strength of the feed solution was maintained at 0.027 M. f, j, b. A current of 200 mA was found to provide a stable reduction of DNT at the 80% level for a period of 14 days after which reactor cleaning is necessary for removal of solids that were formed within the reactor . End products determined for the continuous flow experiments showed 100% molar balance conversion.
Water Sci Technol, 2003, 47(9), 137 - 42
Heterogeneous ultrasonic destruction of aqueous organic contaminants; Suri RP et al.; Sonolysis is emerging as an effective advanced technology for destruction of organic pollutants in wastewater . The focus of this study is to investigate the potential of enhancing the sonochemical destruction of aqueous organics . Increasing the contaminant destruction rate will reduce the reaction time, and possibly reduce the cost of treatment . For this purpose, the effect of H2O2 and/or silica in the presence of ultrasound is examined for destruction of 2-chlorophenol (2-CP) . The effect of silica dosage (1, 5, 10, and 20 g/L), peroxide dosage (60, 75, and 100 mg/L), and pH (3, 7, and 11) is examined . Low solution pH provided higher destruction of 2-CP . The presence of peroxide or silica enhanced the destruction of 2-CP . The optimum silica dosage was 5 g/L . 100 mg/L of peroxide and 5 g/L of silica present together enhanced 2-CP sonolytic destruction by a factor of approximately 2 as compared to 2-CP destruction with ultrasound only.
Water Sci Technol, 2003, 47(9), 71 - 6
Evaluating bioaccumulation of suspected endocrine disruptors into periphytons and benthos in the Tama River; Takahashi A et al.; There are two major routes through which fish are exposed to endocrine disruptors (EDs); one route is through water that is a habitat; the other is through aquatic food such as algae and benthos . Few studies on the bioaccumulation of EDs in food have been conducted . Therefore, we evaluated the concentration in food of nonylphenol (NP), bisphenol A (BPA) and 17beta-estradiol (E2), which were frequently detected in river water and in final discharge of Wastewater Treatment Plants (WWTPs) in Japan . We also evaluated the estrogenicity of samples using recombinant yeast . NP concentrations ranged 0.1-0.4 microg/L in the river water, while they ranged 8-130 microg/kg-wet in the periphytons and 8-140 microg/kg-wet in the benthos . BPA concentrations ranged 0.02-0.15 microg/L in the river water, while they ranged 2-8.8 microg/kg-wet in the periphytons and 0.3-12 microg/kg-wet in the benthos . E2 concentrations ranged 0.0001-0.0076 microg/L in the water, while they ranged 0.09-2.26 microg/kg-wet in the periphytons and <0.01-0.22 microg/kg-wet in the benthos . The estrogenicity ranged 0.0001-0.0464 microg-E2equivalent/L in the water, while it ranged 3.4-66.8 microg-E2equivalent/kg-wet in the periphytons and 7.4-5458 microg-E2equivalent/kg-wet in the benthos . Bioaccumulation factors of NP are estimated as 160-650 for the periphytons, and 63-990 for the benthos, respectively . Bioaccumulation factors of BPA are estimated as 18-650 for the periphytons, and 8-170 for the benthos, respectively . Bioaccumulation factors of E2 are estimated as 64-1,200 for the periphytons, and 100-160 for the benthos, respectively . The ratios of the periphytons and the benthos to the water in terms of the estrogenicity were larger than those in terms of the chemicals . In particularly, the ratio of the benthos to the water is about 10(6) in the maximum . The results suggest that food may be a more important route for fish exposed to EDs in water environment.
Water Sci Technol, 2003, 47(9), 51 - 7
The effect of chlorination of estrogenic chemicals on the level of serum vitellogenin of Japanese medaka (Oryzias latipes); Tabata A et al.; Mature male medaka were continually exposed to four chemicals, p-n-nonylphenol (p-n-NP), nonylphenol (p-NP), bisphenol-A (BPA) and 17beta-estradiol (E2) to evaluate their estrogenic activities in the laboratory . In order to understand the effect of the chlorination that is applied widely in water and wastewater treatment, the above chemicals were chlorinated and then exposed to mature male medaka . Furthermore, in the case of vitellogenin, a is a female specific protein induced by the exposure to test waters containing the above chemicals after 5 weeks, medaka was returned to uncontaminated tap water to determine whether male medaka have a self recovery function from the effect of estrogenic chemicals . Much greater vitellogenin compared to the background levels were induced in the male medaka by separate exposure to 100 microg/L of p-NP, 1,000 microg/L of BPA and 0.05 microg/L of E2 . The levels of vitellogenin increased with increasing exposure periods . The relative potencies of these chemicals descended in the order of E2>>p-NP>BPA . Vitellogenin levels inducible by these chemicals were drastically reduced as a result of the chlorination for 24 hours . However, a moderate increase in hepatocyte somatic index (HSI) meant the hepatic fatness was observed as a result of chlorination . It is not clear at this stage whether or not the formation of chlorination byproducts is responsible for this moderate increase in HSI . The vitellogenin concentration of male medaka exposed to chemicals for 5 weeks decreased gradually after return to the uncontaminated water . However, the vitellogenin concentration did not return to the initial normal levels even after 5 weeks . A clear relationship between the serum vitellogenin concentration and the hepatic vitellogenin concentration was also found . Since quantitative analytical procedures for hepatic vitellogenin are easier than those of the serum vitellogenin, measuring the estrogenic effect using the measurement of vitellogenin in liver is recommended.
FEMS Microbiol Lett, 2003 Jun 27, 223(2), 287 - 92
Extracellular polymeric substances responsible for bacterial adhesion onto solid surface; Tsuneda S et al.; The influence of extracellular polymeric substances (EPS) on bacterial cell adhesion onto solid surfaces was investigated using 27 heterotrophic bacterial strains isolated from a wastewater treatment reactor . Cell adhesion onto glass beads was carried out by the packed-bed method and the results were discussed in terms of the amount of each EPS component produced and cell surface characteristics such as zeta potential and hydrophobicity . Protein and polysaccharides accounted for 75-89% of the EPS composition, indicating that they are the major EPS components . Among the polysaccharides, the amounts of hexose, hexosamine and ketose were relatively high in EPS-rich strains . For EPS-poor strains, the efficiency of cell adhesion onto glass beads increased as the absolute values of zeta potential decreased, suggesting that electrostatic interaction suppresses cell adhesion efficiency . On the other hand, the amounts of hexose and pentose exhibited good correlations with cell adhesiveness for EPS-rich strains, indicating that polymeric interaction due to the EPS covering on the cell surface promoted cell adhesion . It was concluded that, if the EPS amount is relatively small, cell adhesion onto solid surfaces is inhibited by electrostatic interaction, and if it is relatively large, cell adhesion is enhanced by polymeric interaction.
Environ Monit Assess, 2003 Jun, 85(2), 115 - 34
Benchmarking for best practice environmental management; Jenkins BR et al.; Benchmarking of environmental performance to demonstrate the achievement of best practice environmental management is a component of a new form of licensing of industrial discharges in Western Australia . The paper describes the approaches to benchmarking for the critical environmental issues for an alumina refinery and wastewater treatment plant . It also describes the lessons learnt from the benchmarking process on appropriate methods, the benefits and difficulties in the benchmarking process, and changes that would assist benchmarking for best practice environmental management.
Environ Pollut, 2003, 125(3), 385 - 92
Kinetics of basic dye (methylene blue) biosorption by giant duckweed (Spirodela polyrrhiza); Waranusantigul P et al.; Wastewater containing pigments and/or dyes can cause serious water pollution problems in the form of reduced light penetration and photosynthesis, and the toxicity from heavy metals associated with pigments and/or dyes . Laboratory investigations, of the potential use of dried Spirodela polyrrhiza biomass as an adsorbent for the removal of the basic dye methylene blue from aqueous solution were conducted . A series of experiments were undertaken in an agitated batch adsorber to assess the effect of the system variables, i.e . sorbent dosage, pH, and contact time . The results showed that as the amount of the dried S . polyrrhiza increased, the percentage of dye sorption increased accordingly . At pH 2.0 the sorption of dye was not favorable, while the sorption at other pHs (3.0-11.0) was remarkable . There was no significant difference in the dye concentration remaining when the pH was increased from 3.0 to 11.0 . The dye removal time was influenced by the initial dye concentration, and the process followed the first-order rate kinetics . The rate constants for intraparticle diffusion were 1.00 and 3.27 mg/g/min1/2 for 300 and 500 mg/l of dye, respectively.
Sci Total Environ, 2003 Jul 1, 310(1-3), 47 - 59
Trends of phosphorus, nitrogen and chlorophyll a concentrations in Finnish rivers and lakes in 1975-2000; Raike A et al.; During recent decades the amounts of nutrients discharged to Finnish surface waters have markedly decreased . This has been achieved by considerable investments in water protection, which were made mainly to improve municipal and industrial wastewater purification . We investigated whether these water protection measures have decreased phosphorus and nitrogen concentrations in Finnish rivers and lakes . In addition, possible trends in chlorophyll a concentrations in lakes were studied . The data consisted of a total of over 68000 monitoring results of 22 rivers and 173 lakes (or sub-basins of lakes) with different types of catchment areas . The study period covered the years 1975-2000 and the non-parametric Kendall Tau b and Seasonal Kendall tests were applied for detecting trends . Decreasing nutrient concentration trends were typical in many lakes and rivers earlier polluted by municipal and industrial wastewaters . Increasing nutrient concentration trends were common in smaller rivers and lakes receiving diffuse loading from agriculture . The results show that the investments directed towards wastewater purification have effectively improved the quality of Finnish inland waters . However, no clear effects of decreasing non-point loading were found . Thus, more effective measures should be directed towards decreasing non-point source loading.
J Environ Qual, 2003 May-Jun, 32(3), 1122 - 9
Sequestration of phosphorus by acid mine drainage floc; Adler PR et al.; Solubilization and transport of phosphorus (P) to the water environment is a critical environmental issue . Flocs resulting from neutralizing acid mine drainage (AMD) were tested as a possible low-cost amendment to reduce the loss of soluble P from agricultural fields and animal wastewater . Flocs were prepared by neutralizing natural and synthetic solutions of AMD with limestone, lime, ammonium hydroxide, and sodium hydroxide . Phosphorus sequestration was tested in three distinct environments: water, soil, and manure storage basins . In water, flocs prepared from AMD adsorbed 10 to 20 g P kg(-1) dry floc in equilibrium with 1 mg L(-1) soluble P . Similar results were observed for both Fe-based and Al-based synthetic flocs . A local soil sample adsorbed about 0.1 g P kg(-1), about two orders of magnitude less . The AMD-derived flocs were mixed with a high-P soil at 5 to 80 g floc kg(-1) soil, followed by water and acid (Mehlich-1) extractions . All flocs performed similarly . About 70% of the water-extractable P was sequestered by the floc when applied at a rate of 20 g floc kg(-1) soil, whereas plant-available P only decreased by about 30% . Under anaerobic conditions simulating manure storage basins, all AMD flocs reduced soluble P by greater than 95% at a rate of 0.2 g floc g(-1) rainbow trout (Oncorhynchus mykiss) manure . These findings indicate that AMD flocs could be an effective agent for preventing soluble P losses from soil and manure to the water environment, while at the same time decreasing the costs associated with AMD treatment.
ScientificWorldJournal, 2002 Jun 20, 2, 1689 - 98
Can early life-stages of the marine fish Sparus aurata be useful for the evaluation of the toxicity of linear alkylbenzene sulphonates homologues (LAS C10-C14) and commercial LAS?
Hampel M, Moreno-Garrido I, Blasco J.
Most commercial household cleaning agents and personal care products contain the anionic surfactant linear alkylbenzene sulphonates (LAS) as the active compound . After their use they are discharged, theoretically after adequate wastewater treatment, into receiving waters finally reaching estuaries and coastal waters . Laboratory toxicity tests are useful tools in determining at which concentration a certain wastewater compound becomes hazardous for an existing group of organisms . Early life-stage toxicity tests include exposure during the most sensitive development period of the organism . In fish, this type of assay has shown to predict accurately maximum acceptable toxicant concentration (MATC) values (comprised in the range defined by the NOEC and LOEC) in fish early life-stage tests . For this reason, larvae of the seabream, Sparus aurata, were exposed to increasing concentrations of LAS homologues (C10-C14) and commercial LAS . Obtained LC50 values ranged between 0.1 and 3.0 mg l(-1) and were compared with LC50 values of previous hatching experiments with the same species . Larvae proved to be more sensitive to LAS exposure of individual homologues than eggs, except in the case of commercial LAS . LC50 values can be directly employed to determine their potential risk in a concrete environment with known pollutant concentrations . Dividing the LC50 value with the found homologue concentration and extrapolating with certain security factors proposed by different environmental organisms, potentially hazardous pollutant concentrations may be detected . Average estuarine or coastal LAS concentrations are generally below toxicity limits for this kind of organism, considering that the average alkyl chain length of commercial LAS is 11.6 carbon atoms.
ScientificWorldJournal, 2002 Jan 05, 2, 48 - 52
Wastewater minimization in indirect electrochemical synthesis of phenylacetaldehyde; Sun Z et al.; Wastewater minimization in phenylacetaldehyde production by using indirect electrochemical oxidation of phenylethane instead of the seriously polluting traditional chemical process is described in this paper . Results show that high current efficiency of Mn(III) and high yield of phenylacetaldehyde can be obtained at the same sulfuric acid concentration (60%) . The electrolytic mediator can be recycled and there will be no waste discharged.
ScientificWorldJournal, 2002 Apr 26, 2, 1121 - 6
A decontamination process to remove metals and stabilise Montreal sewage sludge; Mercier G et al.; The Montreal Urban Community (MUC) treatment plant produces approximately 270 tons of dry sludge daily (tds/day) during physicochemical wastewater treatment . The sludges are burned and contribute to the greenhouse effect by producing atmospheric CO2 . Moreover, the sludge emanates a nauseating odour during its thermal stabilisation and retains unpleasant odours for the part (25%) that is dried and granulated . To solve this particular problem, the treatment plant authorities are currently evaluating an acidic chemical leaching (sulfuric or hydrochloric acid) process at a pH between 2 and 3, using an oxidizing agent such as ferric chloride or hydrogen peroxide (METIX-AC technology, patent pending; {20}) . They could integrate it to a 70 tds/day granulated sludge production process . Verification of the application of METIX-AC technology was carried out in a pilot plant set up near the sludge production plant of the MUC . The tests showed that METIX-AC technology can be advantageously integrated to the process used at the MUC . The residual copper (274 +/- 58 mg/kg) and cadmium (5.6 +/- 2.9 mg/kg) concentrations in the treated sludge meet legislation standards . The results have also shown that odours have been significantly eliminated for the dewatered, decontaminated, and stabilized biosolids (> 97%) compared to the non-decontaminated biosolids . A high rate of odour elimination also was obtained for the liquid leached biosolids (> 93%), compared to the untreated liquid biosolids . The fertilising value (N and P) is well preserved by the METIX-AC process . Dissolved organic carbon measurements have showed that little organic matter is brought in solution during the treatment . In fact, the average concentration of dissolved organic carbon measured in the treated liquid phase is 966 +/- 352 mg/l, whereas it is 1190 +/- 325 mg/l in untreated sludge . The treated sludge was first conditioned with an organic polymer and a coagulant aid . It was successfully dewatered with various dehydration equipments (filter press, rotary press, centrifuge).
ScientificWorldJournal, 2001 Oct 23, 1 Suppl 2, 908 - 13
ThermoEnergy Ammonia Recovery Process for municipal and agricultural wastes; Fassbender AG; The Ammonia Recovery Process (ARP) is an award-winning, low-cost, environmentally responsible method of recovering nitrogen, in the form of ammonia, from various dilute waste streams and converting it into concentrated ammonium sulfate . The ThermoEnergy Biogas System utilizes the new chemisorption-based ARP to recover ammonia from anaerobically digested wastes . The process provides for optimal biogas production and significantly reduced nitrogen levels in the treated water discharge . Process flows for the ammonia recovery and ThermoEnergy biogas processes are presented and discussed . A comparison with other techniques such as biological nitrogen removal is made . The ARP technology uses reversible chemisorption and double salt crystal precipitation to recover and concentrate the ammonia . The ARP technology was successfully proven in a recent large-scale field demonstration at New York City's Oakwood Beach Wastewater Treatment Plant, located on Staten Island . This project was a joint effort with Foster Wheeler Environmental Corporation, the Civil Engineering Research Foundation, and New York City Department of Environmental Protection . Independent validated plant data show that ARP consistently recovers up to 99.9% of the ammonia from the city's centrate waste stream (derived from dewatering of sewage sludge), as ammonium sulfate . ARP technology can reduce the nitrogen (ammonia) discharged daily into local bodies of water by municipalities, concentrated animal farming operations, and industry . Recent advances to ARP enhance its performance and economic competitiveness in comparison to stripping or ammonia destruction technologies.
ScientificWorldJournal, 2001 Oct 09, 1 Suppl 2, 802 - 8
Multicompartment ecosystem mass balances as a tool for understanding and managing the biogeochemical cycles of human ecosystems; Baker LA et al.; Nitrogen remains a ubiquitous pollutant in surface and groundwater throughout the United States, despite 30 years of pollution control efforts . A detailed multicompartment N balance for the Central Arizona-Phoenix ecosystem is used to illustrate how an ecosystem-level approach can be used to develop improved N management strategies . The N balance is used to demonstrate how nitrate in pumped groundwater used for crop irrigation could be used to reduce inputs of commercial fertilizer and decrease N leaching to aquifers . Effectively managing N pollution also will require an understanding of the complex factors that control the N balance, including targeted regulations, individual human behavior, land-use conversion, and other ecosystem management practices that affect the N balance . These sometimes countervailing factors are illustrated with several scenarios of wastewater treatment technology and population growth in the Phoenix area . Management of N eventually must be coupled to management of other elements, notably carbon, phosphorus, and salts . We postulate that an ecosystem framework for pollution management will result in strategies that are more effective, fairer, and less expensive than current approaches.
ScientificWorldJournal, 2001 Nov 22, 1 Suppl 2, 976 - 83
A potential integrated water quality strategy for the Mississippi River Basin and the Gulf of Mexico; Greenhalgh S et al.; Nutrient pollution, now the leading cause of water quality impairment in the U.S., has had significant impact on the nation"s waterways . Excessive nutrient pollution has been linked to habitat loss, fish kills, blooms of toxic algae, and hypoxia (oxygen-depleted water) . The hypoxic "dead zone" in the Gulf of Mexico is one of the most striking illustrations of what can happen when too many nutrients from inland watersheds reach coastal areas . Despite programs to improve municipal wastewater treatment facilities, more stringent industrial wastewater requirements, and agricultural programs designed to reduce sediment loads in waterways, water quality and nutrient pollution continues to be a problem, and in many cases has worsened . We undertook a policy analysis to assess how the agricultural community could better reduce its contribution to the dead zone and also to evaluate the synergistic impacts of these policies on other environmental concerns such as climate change . Using a sectorial model of U.S . agriculture, we compared policies including untargeted conservation subsidies, nutrient trading, Conservation Reserve Program extension, agricultural sales of carbon and greenhouse gas credits, and fertilizer reduction . This economic and environmental analysis is watershed-based, primarily focusing on nitrogen in the Mississippi River basin, which allowed us to assess the distribution of nitrogen reduction in streams, environmental co-benefits, and impact on agricultural cash flows within the Mississippi River basin from various options . The model incorporates a number of environmental factors, making it possible to get a more a complete picture of the costs and co-benefits of nutrient reduction . These elements also help to identify the policy options that minimize the costs to farmers and maximize benefits to society.
Environ Technol, 2003 May, 24(5), 589 - 96
Environmental assessment of cement/foundry sludge products; Ruiz MC et al.; This work deals with the environmental assessment of products based on cement and a waste from a cast iron activity . The waste is a foundry sludge from wastewater treatment previously characterized . This industrial waste shows a high water content (62.4%) and a hazardous behavior due to its metallic content mainly Zn (16.5%), together with a low fraction of organic pollutants, mainly phenolic compounds . The feasibility of immobilizing both typs of contaminants was studied using Portland cement as binder at different cement/waste ratios . The parameters of environmental control were the ecotoxicity and mobilization of zinc and phenolic compounds, all determined on the basis of compliance leaching tests . The acid neutralization capacity of the cement/waste products was measured in order to obtain information on their buffering capacity . Experimental results from chemical analysis of leachates led to a non ecotoxic character of cement/waste products Although the metallic ions were mobilized within the cement mattices, the organic matter did not allow the formation of monolithic forms and an efficient immobilization of phenolic compounds. a, d, b. Concerning the acid neutralization capacity, this parameter was shown to depend mainly on the quantity of cement, although a decrease in alkalinity was observed when the amount of water in the cement/waste products increased.
Environ Technol, 2003 May, 24(5), 561 - 72
Evaluation of a single-residence biological wastewater treatment system with thermal biosolids destruction; Wistrom AO et al.; An aerobic package residential wastewater treatment system was evaluated to determine process performance while connected to a single-family residence . Three components of the study were: 1) long-term (5-month) performance, 2) 24-hour performance track studies, and
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