Water Treatment

The Increasing pace of Industrialization throughout the world has brought with It a serious, and ever Increasing threat from air pollution. It Is true that this threat Is being taken seriously, and that many responsible research workers, government advisers and others are working towards Its reduction. But air pollution seems to have something of the nature of a hydra-headed monster: tackle one problem and another immediately grows to take its place. Actions taken sometimes have results that are far from what was envisioned, sometimes even seeming to make the problem worse.

In "The Forgotten Pollution", Roos shows clearly and In an often entertaining way, how many of the "unexpected" side effects of pollution by waste gases and particles can be explained by paying attention to the electrical activity of the atmosphere and the earth.
Using an Instrument, which he has developed the Electrostatic Charged Aerosol Monitor (ECAM), together with other instruments and reference to the literature, much of it dating back to the early days of science, when electrostatics was appreciated as a science more than It Is today, Roos has succeeded In explaining many hitherto "puzzling" phenomena in a clear, simple and intellectually satisfying way.

The adsorption of phenol, and halogenated phenols on granular activated carbon (AC) modified with metal oxide catalyst, followed by catalytic oxidative regeneration, was studied as an efficient technology for the treatment of dilute wastewaters. The advantages of the combination of these technologies are as follows: (1) the process will be accelerated by the high concentrations of pollutants eluted from the adsorbent; (2) a large number of adsorption-regeneration cycles are expected without loss in capacity; and (3) the low-temperature regeneration will be conducted in situ, even in small units, thus improving the economy of the process. Oxidative catalytic regeneration of spent carbons, performed at 240-300°C with air, completely restored the adsorption capacity of phenol on the ACs modified with catalyst, even after 10 cycles of regeneration. Under similar conditions, only partial recovery of the adsorption capacity was obtained for carbons loaded with p-chlorophenol and p-bromophenol. The adsorption capacity and the surface area of the AC (Filtrasorb-400) diminished somewhat with the impregnation of oxides (Fe 2 O 3 , CuO, and additivities of Cr 2 O 3 or inert silica), but that did not affect the shape of the adsorption isotherms.

Environmental transformations caused by the economic human activity generate rapid changes in surface water quality. The application of activated carbon in conjunction with microfiltration/ultrafiltration processes is an emergency technology for the removal of organic compounds from water for consumption purposes. This hybrid process (AC-MFAJF) utilizes the capabilities of activated carbon to adsorption of impurities and the microorganisms and particles removal ability of membranes. Ceramic membranes were applied and granulated and powdered activated carbon was used. Changes of volumetric permeate flux in time were estimated and the efficiency of the unit process was compared with the hybrid one, analyzing the physicochemical indexes ofraw water and permeate. Two different methods have been proposed for the mathematical description of hybrid process of natural waters, that is: the model describing the changes of permeate flux in time, the "relaxation" model, and the model of filtration resistance.

As we have broadened our vision of health, the full meaning of water to the human race has begun to reveal itself.  In the most concrete terms, our dependency on water is indisputable. In its 1948 Constitution, the World Health Organization (WHO) defined health as “a complete state of physical, mental and social well-being, and not merely the absence of disease or infirmity”. This paper explores the multi-dimensional connections between water and human health.

The present study deals with the biohydrogen production from starch-containing wastewater collected from the textile industry in Taiwan. The effects of inoculums collected from different sources (sewage sludge, soil and cow dung), substrate concentrations (5–25 g COD/L) and pH (4.0–8.0) on hydrogen production from wastewater were investigated.The cow dung seed had the highest hydrogen production of 101 mL with hydrogen content in biogas of 32.2%. It corresponds to a hydrogen yield (HY) of 1.56 mol H2/mol hexose and hydrogen production rate (HPR) of 0.93 L/L/d. Response surface methodology was used to evaluate the effects of initial cultivation pH (4.0–8.0) and substrate concentration (5–25 g COD/L) on the hydrogen production at 35 °C. At pH 7.0 with a wastewater concentration of 20 g COD/L, a maximum hydrogen production of 66 mL with 31.9% H2 and corresponding to an HY of 0.97 mol H2/mol hexose and an HPR of 1.14 L/L/d were obtained. According to the response surface analysis, the optimal conditions for high HPR were a wastewater concentration of 13 g COD/L at an initial cultivation pH of 7.0. The main soluble metabolic products were acetate and butyrate for hydrogen fermentation from textile wastewater.► The textile wastewater containing starch is a potential energy resource for anaerobic hydrogen fermentation. ► The optimum initial cultivation pH for H2production was 7.0. ► The optimum wastewater concentration for H2 production was 13 g COD/L. ► The main soluble metabolic products were acetate and butyrate.

Ideal bacterial support medium for fixed film denitrification processes/bioreactors must be inexpensive, durable and possess large surface area with sufficient porosity. The present study has been focussed on removing nitrate nitrogen at two different nitrate nitrogen loading rates (60 (NLR I) and 120 (NLR II) mg l-1) from simulated aquaculture wastewater. Coconut coir fibre and a commercially available synthetic reticulated plastic media (Fujino Spirals) were used as packing medium in two independent upflow anaerobic packed bed column reactors. Removal of nitrate nitrogen was studied in correlation with other nutrients (COD, TKN, dissolved orthophosphate). Maximum removal of 97% at NLR-I and 99% at NLR – II of nitrate nitrogen was observed in with either media. Greater consistency in the case of COD removal of upto 81% was observed at NLR II where coconut coir was used as support medium compared to 72% COD removal by Fujino Spirals. The results observed indicate that the organic support medium is just as efficient in nitrate nitrogen removal as conventionally used synthetic support medium. The study is important as it specifically focuses on denitrification of aquaculture wastewater using cheaper organic support medium in anoxic bioreactors for the removal of nitrate nitrogen; which is seldom addressed as a significant problem.

Ozone treatment of steel rebar, together with latex addition (20% by weight of cement) to concrete, resulted in a 39% increase in the shear bond strength between rebar and concrete, compared to a 25% increase resulted from either ozone treatment alone or latex addition alone. Ozone treatment and latex addition resulted in similarly small increases in the contact electrical resistivity between rebar and concrete. Methylcellulose addition (0.4% by weight of cement) to concrete gave slightly less bond strength increase than the latex addition, but did not affect the contact resistivity.

Chitosan is a partially deacetylated polymer obtained from the alkaline deacetylation of chitin which is a glucose-based unbranched polysaccharide widely distributed in nature as the principal component of exoskeletons of crustaceans and insects as well as of cell walls of some bacteria and fungi. Chitosan exhibits a variety of physicochemical and biological properties resulting in numerous applications in fields such as waste and water treatment, agriculture, fabric and textiles, cosmetics, nutritional enhancement, and food processing. In addition to its lack of toxicity and allergenicity, and its biocompatibility, biodegradability and bioactivity make it a very attractive substance for diverse applications as a biomaterial in pharmaceutical and medical fields, where it has been used for systemic and local delivery of drugs and vaccines. It also has bioactive properties in its own right. This paper reviews current veterinary applications for chitosan including wound healing, bone regeneration, analgesic and antimicrobial effects. It also discusses the potential application of chitosan to drug and vaccine delivery in veterinary species. Given the restrictions imposed by financial and animal restraint considerations, especially in farming applications, the veterinary drug delivery areas most likely to benefit from chitosan are the delivery of chemotherapeutics such as antibiotics, antiparasitics, anaesthetics, painkillers and growth promotants to mucosal epithelium for absorption for local or systemic activity, and the delivery of immunomodulatory agents to the mucosal associated lymphoid tissue for induction or modulation of local immune responses. The properties of chitosan expected to enhance these functions are discussed, and the future research directions in this field are indicated.

is to introduce students to open-ended design projects. The purpose of the clinic classes is to provide engineering students with a hands-on, multidisciplinary experience throughout their college education. This type of innovative approach for allowing students to become involved in realistic open-ended design problems is beneficial for enhancing their problem solving skills and encourages them to pursue graduate studies. This paper focuses on the design and development of a laboratory scale water treatment plant for enhancing student learning and understanding. A multidisciplinary student team conducted a thorough literature search and developed an innovative mobile laboratory scale water treatment plant. This plant can be used in various environmental and chemical engineering courses to reinforce unit operations in water treatment. The project focused on treating raw surface water and converting it into potable water by conventional water treatment processes, such as sedimentation, filtration, activated carbon adsorption, ion exchange, and disinfection. Water quality is characterized by standard parameters such as Suspended Solids (SS), Total Solids (TS), Conductivity, pH, Hardness, Turbidity, Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), Nitrate and Fecal Coliform Bacteria. Visual observations along with water quality measurements helps in better understanding of each treatment process. Students are required to calculate conventional design parameters and efficiency of each treatment process. Course evaluations indicate that students have a better understanding of the design of a water treatment plant and its unit operations.

}Ozonation is a disinfection technique commonly used in the treatment of drinking water. It destroys harmful microbes, but it also degrades organic matter in water, increasing the bioavailability of organic matter. Recently, it was found that not only organic carbon but also phosphorus can limit the microbial growth in drinking water, which contains high amount of organic matter. We used a bioassay to analyze whether ozone could also increase the microbially available phosphorus (MAP) in drinking water, and whether MAP in ozone-treated water was associated with the growth of heterotrophic microbes. We found that both assimilable organic carbon and MAP concentrations were increased by ozone treatment. In ozonated water, microbial growth was mainly limited by phosphorus, and even minor changes in MAP concentration dramatically increased the growth potential of heterotrophic microbes. In this study, ozonation increased the MAP by 0.08-0.73 mg P/l, resulting in an increase of 80,000-730,000 CFU/ml in water samples. In contrast to MAP, the content of assimilable organic carbon (AOC potential) did not correlate with microbial growth. The results show that in water treatment not only AOC potential but also MAP should be considered as an important factor that can limit microbial growth in drinking water.

Recently, a novel approach to a highly sensitive and quantitative detection of rare earth element (REE) ions including La3+, Eu3+ and Tb3+, by the polymerase chain reaction (PCR) technique, has been reported. The detection of REE ions is based on the catalytic nature of REE ions targeting the deoxyribonucleic acid (DNA), thus monitoring of the ions can be achieved by reading the level of intact DNA by PCR. Despite of its high sensitivity (at ppb to ppt levels), the conventional PCR-based REE detection protocol requires certain length of time (1-2 hours). In the present study, we modified the PCR-based REE detection protocols by employing the high-speed PCR, and performed the automated and rapid detection of La3+ in small-sized aqueous samples within 5min.

Batang Ai reservoir has been an inland aquaculture site. However, little is known about the water quality of the reservoir which is important for aquaculture expansion. Therefore, the objective of this study was to determine the level of dissolved oxygen (DO), biochemical oxygen demand (BOD 5 ) and sulfide in the reservoir. Samplings were conducted at 12 stations and at three different depths. Results show that pH and dissolved oxygen decreased as depth increased. Mean DO at 0.5 m, 14 m and 27 m were 6.4 mg/L, 3.9 mg/L and 2.95 mg/L respectively. BOD 5 were 3.9 mg/L, 8.7 mg/L and 8.3 mg/L at 0.5 m, 14 m and 27 m depth respectively. Total sulfide ranged from 0.33 to 32.0 µg/l and the mean at 27 m was significantly higher than 0.5 m depth. Multiple linear regression indicates that BOD 5 was the only significant predictor of total sulfide. This study shows that sulfide was much lower than the lethal level and it would only be unhealthy for the caged fish if there were upwelling or mixing where lower DO water with toxic sulfide at and below 14 m depth were to be brought to the culture zone.

Groundwater pollution by nitrates is a widespread problem in many locations in the world. The underground aquatic mantle of the Peninsula of Yucatan is highly vulnerable due to its karstic nature. Adsorption methods are a good choice for nitrate elimination. In this work, a natural calcium bentonite was modified by acid thermoactivation with HCl and H 2 SO 4 , and tested as a media for nitrate removal in an aqueous solution. The nitrate concentration in the solution was measured by FT-IR, using the Lambert-Beer law. Clay characterization was carried out by X-ray diffraction and FT-IR spectroscopy; surface area was measured by the BET method. #

Perchlorate (ClO 4 2 ) release into the environment has occurred primarily in association with its manufacture and use in solid rocket propellant. When released into groundwater, perchlorate can spread over large distances because it is highly soluble in water and adsorbs poorly to soil. Two proven techniques to remove perchlorate from drinking water are anaerobic biological reactors and ion exchange. In this review, we focus on the application of microbiological systems for degrading perchlorate. Some bacteria can use perchlorate as an electron acceptor while oxidizing a large range of substrates. Perchlorate-respiring bacteria (PRB) are widely distributed in the environment, and are enriched at perchlorate-contaminated sites. We review the pathways by which PRB degrade perchlorate, and the different biological treatment processes that have been developed to remove perchlorate from water sources. We also discuss the effects of alternate electron acceptors in the water, such as oxygen and nitrate, on perchlorate removal. Although many different biological treatment systems using PRB have so far only been proven at the bench scale, all pilot scale tests performed to date with a few of these systems have been successful. The success of these perchlorate bioreactor tests indicates that biological treatment is a suitable method for soil remediation and water treatment of perchlorate-contaminated water.

This study provides a preliminary contribution to the development of an industrial process for 2 the UV/TiO2 water treatment by introducing a novel support for TiO2 immobilization. For the 3 following study, Methylene Blue (MB) was chosen as the model dye to evaluate this novel 4 immobilization system. The results showed that TiO2 immobilized in a Ca-alginate bead 5 retained its photoactivity during all of the experiments and the TiO2-gel beads presented good 6 stability in water for maintaining its shape after several uses. When a proportion of 10% (v/v) 7 of these beads was used, the configuration system demonstrated an improved mass transfer 8 and consequently enhanced degradation efficiency. Experiments were also performed using 9 'recycled' beads., The results showed an increase in the degradation efficiency when the 10 beads were reused, with an eventual 'self-destructive' effect. These studies showed great 11 promise regarding the recyclable reagents with a reduction in waste at no greater cost or 12 reduction in efficiency. Therefore, the potential of TiO2-gel beads as a simple and 13 environmentally friendly catalyst for continuous use was developed. 14

segments the crop protection chemicals market with currant trends and forecasting of the revenues for herbicides, fungicides and insecticides. It also identifies the driving and restraining factors for the crop protection chemicals market with analysis of drivers, opportunities and challenges. The market segmented and revenues are forecasted on the basis of major countries such as U.S., Canada and Brazil. Further, the market is segmented and revenues are forecasted on the basis of product types and crop types.

This paper presents and discusses the role of community engagement, i.e. attitudes of local stakeholders, engagement of elected officers and pricing, towards the success of water reuse on the island of Bora Bora, French Polynesia. To better preserve public health and overcome all constraints related to public perception, a membrane tertiary treatment was implemented for the production of high-quality recycled water. Consequently, the demand for the new recycled water has steadily increased during the last four years with a wide diversification of urban uses including irrigation, cleaning, industrial and commercial uses and fire protection. The primary keys to success of this water reuse scheme are the strong commitment of elected officers and large industrial users with the implementation of an adequate public communication and education programme. The resulting outcome is the public trust in recycled water and the recognition of the economic and environmental benefits of water reus...

A significant consideration in forward planning for water treatment works design and operation concerns the effectiveness of a filtration plant in providing a barrier to particulates in the low micrometre size range, including Cryptosporidium oocysts. The performance of rapid gravity filtration ...

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.

ABSTRACT River water cleaning from microorganisms using electrohydraulic discharges and ozonation was investigated. The processed water was highly polluted with the total number of microorganisms (70 400 cfu/mL) and total Escherichia coli bacteria (280 cfu/mL). The processing was conducted in a tube reactor with a hollow needle-rod electrode configuration. A 400-mL sample of river water was treated at different flow rates. Ozonation was performed in a washing bottle with an ozone concentration of 20 g/m3. The corona discharge treatment showed a steady decrease of bacteria and microorganisms but did not kill them completely. Spark discharge killed the bacteria and microorganisms completely; however, its energy efficiency was much lower than that of ozonation. The ozone treatment decreased the concentration of microorganisms and coli bacteria down to 785 and 10 cfu/mL, respectively, in 45 s which resulted in higher energy efficiency than processing using corona and spark discharges. The NPOC analysis of the treated samples showed its concentration of 5 ± 0, 4 ppm in all samples.

The EU project SAFIR aimed to help farmers solve problems related to the use of low quality water for irrigation in a context of increasing scarcity of conventional freshwater resources. New decentralised water treatment devices (prototypes) were developed to allow a safe direct or indirect reuse of wastewater produced by small communities/industries or the use of polluted surface water. Water treatment technologies were coupled with irrigation strategies and technologies to obtain a flexible, easy to use, integrated management of the system. The challenge is to apply new strategies and technologies which allow using the lowest irrigation water quality without harming food safety or yield and fruit or derivatives quality. This study presents the results of prototype testing of a small-scale compact pressurized membrane bioreactor and of a modular field treatment system including commercial gravel filters and heavy-metal specific adsorption materials. Decentralised compact pressurised membrane biobooster (MBR), was able to remove up to 99.99% of the inlet Escherichia coli and 98.52% of total coliforms. E. coli was completely removed from irrigation water in 53% of the samples by the last MBR prototype version. In 2008, 100% of samples fulfilled WHO standards (1989) and Global Gap requirement for faecal contamination. MBR removed from inlet flow in the average 82% of arsenic, 82% of cadmium, 97% of chromium, 93% of copper and 99% of lead. Boron and manganese were not removed from permeate. The field treatment system (FTS) proved to be effective against faecal contamination when applied with its complete set up including UV treatment. The sole gravel filter and heavy metal removal device (HMR) cannot provide sufficient and steadily treatment for microbial contamination. Nevertheless, gravel filter can remove up to 60% of E. coli but the removal process was not stable nor predictable. FTS removed 76% of arsenic, 80% of cadmium and copper, 88% of chromium and lead, and up to 97% of zinc. Like the MBR, boron and manganese were not removed from the irrigation water. Gravel filter directly fed with secondary treated wastewater was found able to remove 41% of arsenic, 36% of cadmium and lead, 48% of chromium and 46% of copper. The residual heavy metals concentration after the gravel filter was further reduced by the HMR: 35% for arsenic, 22% for cadmium, 25% for chromium, 33% for copper and 53% for lead.

Titania, TiO2, irradiated by ultraviolet/visible light was used to mediate the photocatalyzed degradation of ortho-cresol, meta-cresol, and para-cresol. The total photomineralization of these phenols to carbon dioxide and water occurs in air-equilibrated aqueous media. Two major hydroxylated aromatic intermediate species have been identified by liquid chromatographic methods: 4methylcatechol and methylhydroquinone. Photochemical efficiencies (lower limits of quantum yields, 365 nm) of compound disappearance are, respectively, 0.0096, 0.0076, and 0.010 for o-, m-, and p-cresol. The effect of such parameters as pH, initial cresol concentration, and radiant power levels on the degradation of m-cresol was examined in detail. Although the photodegradation process kinetics show similarities with Langmuir-Hinshelwood-type behavior, namely saturation, it is shown that the resulting kinetic expression for the rate of degradation is a complicated function of various parameters and is silent as to the details of the initial photooxidative steps. It is implicitly argued, however, that the reaction takes place on the semiconductor particle surface.

Background: The increased efficiency of the sedimentation tanks at refineries to the technical and economic reasons are important, therefore the feasibility of increasing the efficiency of sedimentation tanks by modeling and optimization of the tanks, is necessary. Method: In this study, using thin layer plates in mineral sedimentation tanks have been investigated in the laboratory practice and by using mathematical modeling, feasibility and efficiency of the actual volume of the tanks equipped with the usual conditions in the sedimentation tanks, have been compared. Results:Results indicate that efficiency is the same and equal Е = 53% ,Time required for settling tanks equipped with thin layer plates in comparison with conventional tanks, equal to 2.64, is lower.The maximum flow rate in tanks equipped with thin layer plates in comparison with conventional tanks, equal to 1.6, is increased. Conclusion: Thin layer plates, improvements the process of mineral sedimentation significantly, this is based on increasing surfaces of sedimentation, the laminar flow, reducing the level of suspended solids from settling and removal of short connections inside the tank, is based. [Mohammad soleimani, Mirali mohammadi. Feasibility of increasing the efficiency of primary settling tanks by using thin layer plates.

Photocatalytic reduction of mercury in aqueous solutions using PW 12 O 40 3or SiW 12 O 40 4as photocatalysts has been studied as a function of irradiation time, concentration of Hg(II), polyoxometalate, and organic substrate in the presence or absence of dioxygen. The photocatalytic cycle starts with irradiation of polyoxometalate, goes through the oxidation of, for instance, propan-2-ol (used as sacrificial reagent), and closes with the reoxidation of reduced polyoxometalate by Hg 2+ ions. Mercury(II) is reduced to mercury(I) and finally to Hg 0 giving a dark-gray deposit, following a staged one-by-one electron process and a firstorder kinetics in [Hg 2+ ]. The process is slightly more efficient in the absence of dioxygen, while the increase of either catalyst or propan-2-ol concentration results in the augmentation of the rate of reduction till a certain point where it reaches a plateau. The results show that this method is suitable for a great range of mercury concentration from 20 to 800 ppm achieving almost complete recovery of mercury up to nondetected traces (<50 ppb). In addition, this homogeneous process demonstrates advantages such as the lack of necessity for separation of the zero state metal from the catalyst and ensures that the precipitation of metal will not poison the catalyst or hinder its photocatalytic activity.

Abstract. Due to the fact that corrosion problems affecting the residual water treatment industry are varied and scarcely studied, this work presents an investigation of the corrosion behavior of important materials of engineering such as steel AISI-1018, AISI-304, and AISI-800 exposed to synthetic residual water under laboratory conditions. The electrochemical techniques used to asses the electrochemical behavior were linear polarization resistance (LPR), cyclic polarization curves (CPC) and electrochemical noise (ECN) techniques to determine corrosion rates, the susceptibility to localized corrosion and the most likely corrosion mechanism, respectively. In order to ascertain the amount of aerobic and anaerobic bacteria present on the steel surface, the Most Probable Number method (MPN) was employed. On the whole, the steels studied showed a better corrosion resistance in the following order: 800 > 304 > 1018. Also, the experimental results indicated that none of the steels demonstrated susceptibility to localized corrosion.

In this paper are reported experimental results on the effect of a magnetic field on the precipitation process of calcium carbonate scale from a hard water. Carbonically pure water was circulated at a constant flow rate in a magnetic field. After this treatment, calcium carbonate precipitation was induced by degassing dissolved carbonic gas. The nucleation time was identified from the variations of the pH and the Ca 2+ concentration. The ratio between homogeneous and heterogeneous nucleation was determined from the measurement of the mass of precipitated calcium carbonate. It is shown that the magnetic treatment increases the total amount of precipitate. This effect depends on the solution pH, the flow rate and the duration of the treatment. In addition, the magnetic treatment modifies the ratio between homogeneous/heterogeneous nucleation. Homogeneous nucleation is promoted by an increasing the pH of water, the flow rate as well as the residence time. The magnetic treatment enhances these effects with a maximum for a 15 min treatment time. It is shown that the presence of calcium carbonate colloid particles is not necessary. It is advanced that the main magnetic effects concern the associations of ionic species which are present in the solution and which are involved in the nucleation process of calcium carbonate precipitation

The utilities at a major government office facility include both a condenser and a chilled water system. Although they are similar, the water in the first is regularly aerated, while the other is a closed system. The piping in both is largely carbon steel, with minor cast iron. Both systems used Victaulic couplings rather than welded joints. The joints in the condenser section of the system are deeply corroded, while the chilled water system is in good condition. A study was implemented to determine the root cause of the failures in the condenser system, to review operating procedures to determine if they were involved in the failures, and to recommend future actions to repair the system and prevent further damage. Examination of the system showed that the interior surfaces of most of the pipe were heavily covered with a thick tan and black tubercular deposit, largely iron oxides and oxyhydroxides, with minor calcium carbonate. Prior to use the original pipe interior surfaces were unprotected by any coating; the present surfaces are broadly, but not deeply, corroded. However, the lips of many of the joints, between the rubber gaskets, have suffered major material loss through corrosion. Comparison of the microbiology of the metal surfaces of the joints and the gaskets at those joints in the two systems showed that there were significantly greater concentrations of aerobic and anaerobic bacteria at both of those locations in the condenser water system than in the chilled system, particularly on the gaskets. These bacteria are not detected by the normal plate counts run by the water treatment provider. However, slime-forming and iron-degrading bacteria have been specifically identified in the pipe joints by Polymerase Chain Reaction analysis and DNA sequencing techniques. Chemical analysis of the deposit in one of the joints shows an extremely high sulfur concentration (2.3%), indicative of the presence of active sulfur-reducing bacteria. Water analyses show relatively high sulfur and chloride contents. The design of the specific Victaulic couplings appears to be related to the failures as all the failures occurred in only one model of joint and not in others. In addition, aeration of the condenser water and operating procedures may have had major roles in the failures. The system may have been pressure tested and then left standing for as much as several months before formal operation began. The root cause of the failure appears to have been this procedural mistake. Bacteria may have colonized the joint areas during that interval, and no amount of subsequent biocide treatment was likely to penetrate the resultant biofilms in these protected joint areas. The metabolic processes of the various forms of bacteria comprising the biofilms would be responsible for promoting much of the corrosion now seen to have taken place. The difference in dissolved oxygen between the two systems also accounts in part for the difference in corrosivity of the waters in them.

The efficiency of Zinc Oxide nanoparticles on removal of E124 dye in aqueous solution has been studied. Different factors and parameters that affect the degradation efficiency of E124 dye were studied including the initial concentration of pollutant, pH of solution, treatment time, concentration of ZnO nanoparticle (ZnO NP), temperature and salt addition. Under the achieved optimal conditions (initial concentration of dye solution 5ppm, treatment time 80 min, concentration of ZnO NP 0.08g, pH 7 and temperature of 40 0C) for best removal of E124 dye from aqueous solution the efficiency of ZnO NP doped with Ag+ was tested. Different amounts of Ag+ % doped on ZnO NP from 0.5 to 2% were tested and the highest dye removal % of 92 was achieved at 1 % Ag+ doping of ZnO NP.

Water treatment plays a vital role in the delivery of safe and effective hemodialysis (HD). Ensuring that water quality meets the American Association for the Advancement of Medical Instrumentation standards and recommendations (or equivalent) is necessary to reduce the incidence of chemical hazards and endotoxemia associated with the use of water for HD. This review will discuss the principles of water treatment for HD, the essential components of water purification, the recommended system monitoring and maintenance procedures, and some of the historical incidents of adverse reactions that resulted from the use of contaminated dialysis water.

Sorption of phosphorus (P) to the bed sand medium is a major removal mechanism for P in subsurface flow constructed wetlands. Selecting a sand medium with a high P-sorption capacity is therefore important to obtain a sustained P-removal. The P-removal capacities of 13 Danish sands were evaluated and related to their physico-chemical characteristics. The P-removal properties of sands of different geographical origin varied considerably and the suitability of the sands for use as media in constructed reed beds thus differs. The P-sorption capacity of some sands would be used up after only a few months in full-scale systems, whereas that of others would subsist for a much longer time. The most important characteristic of the sands determining their P-sorption capacity was their Ca-content. Also the P-binding capacities of various artificial media were tested (light-expanded-clay-aggregates (LECA), crushed marble, diatomaceous earth, vermiculite and calcite). Particularly calcite and cr...

There is a need for a low cost, sensitive, on-line sensor to assess the integrity of membrane modules used in the water industry for water treatment, membrane bioreactors and for pre-treatment prior to using nanofiltration or reverse osmosis. A sensor addressing this need is described whose operating principle is based on measuring the differential pressure across a membrane that intercepts a portion of the permeate from the pre-treatment module(s) relative to the differential pressure across a valve. The latter can be adjusted to maximize the sensitivity of the instrument. A dimensionless metric based on the differential pressures is defined and corroborated with the Silt Density Index. The sensitivity of this Integrity Sensor is demonstrated by its response to cutting one fiber in a UF pre-treatment module that contains 1500 hollow fibers.

An in-line coagulation (without settling)/UF process has been studied to improve membrane performance and water quality for surface water treatment. Using coagulation before UF increases permeate quality; the extent of dissolved organic matter removal is controlled by the coagulation step. Efficient coagulation conditions for a coagulation/settling process can be applied for the in-line coagulation/UF process and membrane fouling is reduced. Floc cake resistance is lower than resistance due to the unsettled floc and the uncoagulated organics. For an insideout hollow-fiber system, the impact of coagulation dose depends on filtration mode: for instance, in cross-flow with a feed-and-bleed configuration, a reduction of coagulant dose induces an increase of the mass transfer resistance even in quasi-stable hydrodynamic operating conditions.

During the 1990s, passive treatment technology was introduced to the United Kingdom (UK). Early hesitancy on the part of regulators and practitioners was rapidly overcome, at least for net-alkaline mine waters, so that passive treatment is now the technology of choice for the long-term remediation of such discharges, wherever land availability is not unduly limiting. Six types of passive systems are now being used in the UK for mine water treatment:

En el Acuario de Veracruz, el sistema de filtración mecánico-biológico es el proceso unitario fundamental para mantener el agua en condiciones ideales para los organismos que se encuentran en las peceras y estanques. El medio filtrante sirve de sustrato para albergar bacterias nitrificantes que oxidan el amonio, el cual resulta perjudicial para los ejemplares. El objetivo de esta investigación fue determinar el caudal óptimo de operación de los filtros para conseguir la máxima eficiencia de remoción de amonio del agua por efecto microbiológico bajo diferentes tiempos de residencia. De acuerdo con los resultados, el caudal de operación de los filtros afecta de forma directa la eficiencia de remoción de amonio, encontrándose óptimo un caudal inferior a 1 L/s independientemente para cada uno de ellos.

Two a-alumina ceramic membranes (0.2 and 0.8 jam pore sizes) and a surface-modified polyacrylonitrile membrane (0.1 jam pore size) were tested with an oily water, containing various concentrations (250-1000 ppm) of heavy crude oil droplets of 1-10 ~tm diameter. Significant fouling and flux decline were observed. Typical final flux values (at the end of experiments with 2h of filtration) for membranes at 250ppm oil in the feed are ~30-40kg m-2 h-1. Increased oil concentrations in the feed decreased the final flux, whereas the crossflow rate, transmembrane pressure, and temperature appeared to have relatively little effect on the final flux. In all cases, the permeate was of very high quality, containing <6 ppm total hydrocarbons. The addition of suspended solids increased the final membrane flux by one order of magnitude. It is thought that the suspended solids adsorb the oil, break up the oil layer, and act as a dynamic or secondary membrane which reduces fouling of the underlying primary membrane. Resistance models were used to characterize the type of fouling that occurs. Both the 0.2 jam and the 0.8 jam ceramic membranes appeared to exhibit internal fouling followed by external fouling, whereas external fouling characterized the behavior of the 0.1 jam polymer membrane from the beginning of filtration. Examination of the external fouling layer showed a very thin hydrophobic oil layer adsorbed to the membrane surface. This oil layer made the membrane surface hydrophobic, as demonstrated by increased water-contact angles. The oil layer proved resistant to removal by hydrodynamic (shear) methods. By extracting the oil layer with tetrachloroethylene, followed by IR analysis, its average thickness at the end of a 2 h experiment under typical conditions was determined to be 60 ~tm for the 0.2 jam ceramic membrane and 30 jam for the 0.1 jam polymer membrane. These measured amounts of oil associated with the membrane at the end of the experiments are in good agreement with those determined from a simple mass balance, in which it is assumed that all of the oil associated with the permeate collected is retained on or in the membrane, indicating that the tangential flow did not sweep the rejected oil layer to the filter exit.

An evaluation was conducted in 2007 on biosand fi lters that were installed in Posoltega, Nicaragua in 1999 and 2004. The objectives were to characterize the condition and use of fi lters eight and three years after installation, determine fi lter performance of those fi lters still in use, and identify determinants of successful long-term use and performance. Methods consisted of household identifi cation, user questionnaires, and water quality testing. Of the 234 fi lters installed, only 24 were found to still be in use. Average log reductions were 1.73 (98%) for total coliforms, 1.36 (96%) for Escherichia Coli, and 0.91 (88%) for turbidity. Statistically signifi cant effects were detected for the magnitude of the contamination of source water, the peak hydraulic loading rate, and the standing depth of water over the fi lter media. Questionnaire results indicated user training on fi lter maintenance could improve the peak hydraulic loading rate and hence fi lter performance. The low rate of sustained use (10%) is an indication of failed implementation, and is attributable to structural failure, particularly cracking of the concrete fi lters from 2004. Nonetheless, this evaluation demonstrated the biosand fi lter technology to be robust since those fi lters still in use were performing as expected three and eight years postimplementation.

Unpleasant tastes and odors in drinking water from the upper St. Lawrence River were investigated in the fall of 1996 and 1997 as the result of increasing taste and odor events in recent years. Taste and odor events resulted in widespread public reaction to the earthy/musty tasting water produced and a need for accurate information to assist water treatment efforts. The presence of geosmin, (trans, trans-1,10-dimethyl-9-decalol) and 1,2,7,heptan-2-ol), the most common causes worldwide of earthy and musty odors in water, were investigated in eastern Lake Ontario and the upper St. Lawrence River. Gas chromatography-mass spectrometry was used for quantitation and confirmation of the presence of these compounds in water samples. Both geosmin and MIB2 were detected in river water samples at concentrations ranging from 5 to 20 ng/L and 2 to 25 ng/L, respectively. The compounds were also detected in southern coastal lake water which serves as a source to the St. Lawrence River, but not in mid-lake samples. Similar levels of geosmin and MIB2 were detected in untreated Lake St. Lawrence water, in samples taken following pre-chlorination for zebra mussel control, and in samples taken following conventional treatment at a water filtration plant.

Adequate rejection of a variety of inorganic and organic compounds is necessary if reverse osmosis (RO) and nanofiltration (NF) membranes are to be used for space mission wastewater reuse. Three ersatz space mission wastewaters defined by NASA having different pH (2.6-8.9), conductivities (3980-12,640 mS/cm), and amounts of organic compounds (50-2400 mg/L as carbon) were tested to determine the membrane flux and the solute rejection for five RO and two NF membranes that are commercially available. The results show that the rejection of ions depends upon the solution pH which influences electrostatic repulsion. However, the rejection of dissolved organic carbon (DOC) depends upon the composition of the wastewater. The DOC rejection (80-95%) was the highest for the wastewater containing dextran (molecular weight 15-20 k) compared with the other ersatz wastewaters having detergent and urea as the major carbon sources (31-83%). The wastewater having the greatest conductivity (12,640 mS/cm) and DOC (2400 mg/L) showed a greater flux decline (71-96%) than the other ersatz wastewaters (37-82%) having lower conductivities (3980-6980 mS/cm) and DOC (50-660 mg/L) for the RO and NF membranes. The ratio of solute radius (r i,s ) to effective membrane pore radius (r p ) was employed to compare ion rejection. For ionic compounds, the rejection is higher than 70% when the r i;s =r p ratio is greater than 0.5 for both the RO and NF membranes with all wastewaters. r