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Water Distribution Systems (water + distribution_system)
Selected AbstractsEffect of Well Disinfection on Arsenic in Ground WaterGROUND WATER MONITORING & REMEDIATION, Issue 2 2008Madeline Gotkowitz Domestic water wells are routinely subjected to in situ chemical disinfection treatments to control nuisance or pathogenic bacteria. Most treatments are chlorine based and presumably cause strongly oxidizing conditions in the wellbore. Water resource managers in Wisconsin were concerned that such treatments might facilitate release of arsenic from sulfide minerals disseminated within a confined sandstone aquifer. To test this hypothesis, a well was subjected to four disinfection treatments over 9 months time. The first treatment consisted of routine pumping of the well without chemical disinfection; three subsequent treatments included chlorine disinfection and pumping. Pretreatment arsenic concentrations in well water ranged from 7.4 to 18 ,g/L. Elevated arsenic concentrations up to 57 ,g/L in the chemical treatment solutions purged from the well are attributed to the disintegration or dissolution of biofilms or scale. Following each of the four treatments, arsenic concentrations decreased to less than 10 ,g/L during a period of pumping. Arsenic concentrations generally returned to pretreatment levels under stagnant, nonpumping conditions imposed following each treatment. Populations of iron-oxidizing, heterotrophic, and sulfate-reducing bacteria decreased following chemical treatments but were never fully eradicated from the well. Strongly oxidizing conditions were induced by the chlorine-based disinfections, but the treatments did not result in sustained increases in well water arsenic. Results suggest that disruption of biofilm and mineral deposits in the well and the water distribution system in tandem with chlorine disinfection can improve water quality in this setting. [source] Exploring the species diversity of Trichoderma in Norwegian drinking water systems by DNA barcodingMOLECULAR ECOLOGY RESOURCES, Issue 6 2008GUNHILD HAGESKAL Abstract A total of 123 Trichoderma strains were isolated from Norwegian surface-sourced drinking water. The water samples included raw water, treated water, and water from private homes and hospital installations. Trichoderma species are difficult to differentiate morphologically, but recent molecular identification tools, including DNA barcoding, successfully distinguish between closely related species. The diversity of Trichoderma spp. was explored by DNA sequencing of internal transcribed spacer (ITS) and translation elongation factor 1 alpha (TEF-1,). Sequence identification was performed in the TrichOKEY version 2.0 barcode program and in the multilocus similarity search database TrichoBLAST, combined with traditional blast searches in the EMBL/GenBank. A total of 11 known Trichoderma/Hypocrea species were identified. In addition, one group of unidentified Trichoderma strains was found to represent a separate, strongly supported subclade within the Pachybasium,A'/Hamatum clade, based on their TEF-1, haplotypes. Trichoderma viride comprised 49% of the identified strains, and was represented by four and eight slightly different ITS and TEF-1, haplotypes, respectively. Approximately 22% of the surface-derived water samples were positive for T. viride, and the species was frequently isolated throughout the surface-sourced drinking water distribution system. The results indicate that a broad range of Trichoderma species are present in Norwegian surface-sourced drinking. Water treatment has minor effect in removing Trichoderma from raw water, and active growth in the water distribution system is likely to occur. [source] Steady-State Analysis of Water Distribution Networks Including Pressure-Reducing ValvesCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 4 2001L. Khezzar Hydraulic networks that contain controlling elements such as pressure-reducing valves (PRVs) are difficult to simulate. Limited literature exists on the explicit modeling of PRVs in a general solution procedure for steady-state analysis of water distribution systems. It is also known that inclusion of PRVs may lead to numerical difficulties. The objective of this article is to develop and present in sufficient detail the modeling of PRVs in combination with the linear theory method for steady-state analysis of water distribution networks. The presentation is explicit enough and leads to a robust algorithm that can be directly implemented in a computer program. The general methodology for simulating water distribution networks that embodies graph theoretic concepts, hydraulic theory, and numerical algorithms is reviewed. [source] Perchlorate reduction by a novel chemolithoautotrophic, hydrogen-oxidizing bacteriumENVIRONMENTAL MICROBIOLOGY, Issue 10 2002Husen Zhang Summary Water treatment technologies are needed that can remove perchlorate from drinking water without introducing organic chemicals that stimulate bacterial growth in water distribution systems. Hydrogen is an ideal energy source for bacterial degradation of perchlorate as it leaves no organic residue and is sparingly soluble. We describe here the isolation of a perchlorate-respiring, hydrogen-oxidizing bacterium (Dechloromonas sp. strain HZ) that grows with carbon dioxide as sole carbon source. Strain HZ is a Gram-negative, rod-shaped facultative anaerobe that was isolated from a gas-phase anaerobic packed-bed biofilm reactor treating perchlorate-contaminated groundwater. The ability of strain HZ to grow autotrophically with carbon dioxide as the sole carbon source was confirmed by demonstrating that biomass carbon (100.9%) was derived from CO2. Chemolithotrophic growth with hydrogen was coupled with complete reduction of perchlorate (10 mM) to chloride with a maximum doubling time of 8.9 h. Strain HZ also grew using acetate as the electron donor and chlorate, nitrate, or oxygen (but not sulphate) as an electron acceptor. Phylogenetic analysis of the 16S rRNA sequence placed strain HZ in the genus Dechloromonas within the , subgroup of the Proteobacteria. The study of this and other novel perchlorate-reducing bacteria may lead to new, safe technologies for removing perchlorate and other chemical pollutants from drinking water. [source] The effect of introducing pipelines into irrigation water distribution systems on the farm economy: a case study in the Southern Governorates Rural Development Project, Republic of Yemen,IRRIGATION AND DRAINAGE, Issue 1 2001Rozgar Baban le Yémen; eau souterraine; irrigation; tuyaux Abstract The Southern Governorates Rural Development Project (SGRDP) is a comprehensive participatory rural development project covering three of the five southern Governorates of the Republic of Yemen, namely Hadramaut, Abyan and Lahij. Its objective is to alleviate poverty in rural areas of these three Governorates. A major component of the project is to develop virgin lands for agriculture and allocate each 5 feddan (FD) plot to those farmers who do not own land (1 FD=4200 m2). As the annual rainfall in the project area is less than 100 mm and since landlords and other farmers already own lands suitable for agriculture in the major wadis, the only source of irrigation water in the newly developed land is the groundwater (GW). The SGRDP is aware of the scarcity of water resources in the country, particularly in the project area; it therefore makes every possible effort to optimize the use of GW for irrigation by practical means. One way of reducing GW used for irrigation is by replacing major canals in the farms by buried pipelines. This method has been tried in small-scale individual farms outside the project area and it proved that farmers could adapt to the system without difficulty. Sprinkler and drip irrigation systems have been tried in many previous agricultural development projects in the country but with no apparent success, as far as the farmers' adoption of the method is concerned. Thus, the project, as the first stage to reduce the use of GW for irrigation in the newly developed areas, planned to eliminate, initially, the conveyance losses by replacing the open canals by buried PVC pipes. In this paper, it is attempted to show that the use of buried pipes in small scale irrigation schemes is financially feasible, even if the indirect and non-tangible environmental benefits are not considered. This paper deals only with special GW schemes recommended for the project area; however, the outcome could be generalized and applied elsewhere in the country. Copyright © 2001 John Wiley & Sons Ltd. Le Projet de Développement Rural des Gouvernorats du Sud (SGRDP) est un ensemble de projet de développement rural participatif de trois des cinq Gouvernorats de la République de Yémen à savoir Hadramaut, Abyan et Lahij. Son objectif est d'atténuer la pauvreté dans les régions rurales de ces Gouvernorats. L'une des principales activités de ce projet concerne le développement des terres incultes pour l'agriculture. Ce développement passe par l'allocation de parcelles de 5 FD à chaque agriculteur sans terre. Comme la pluviosité annuelle dans cette région est inférieure à 100 mm et que les propriétaires et les autres fermiers disposent déjà des terres aptes à l'agriculture dans les WADIS importants, l'eau souterraine est la seule source d'eau pour l'irrigation des terres nouvellement développées. Compte tenu de la rareté des ressources en eau, particulièrement dans la région du projet, le SGRDP s'efforce d'optimiser l'utilisation de l'eau souterraine (ES) pour l'irrigation en adoptant des moyens pratiques. L'un des moyens de réduire l'ES utilisée en irrigation consiste à remplacer les principaux canaux des fleuves par des tuyaux enterrés. Cette méthode a été utilisée à titre d'essai dans des exploitations individuelles de petite taille en dehors de la région du projet, et il s'est avéré que les agriculteurs peuvent s'adapter à ce système sans difficultés. Les systèmes d'irrigation par aspersion et goutte à goutte ont été essayés dans de nombreux anciens projets de développement agricoles du pays, mais sans succès apparent quant à l'adoption de cette méthode par les fermiers. Ainsi, le projet, en tant que première stade de réduction de l'ES pour l'irrigation dans les régions nouvellement développées, a proposé d'éliminer au début les pertes par transport en remplaçant les canaux ouverts par des tuyaux PVC enterrés. Ce rapport essaie de montrer que l'utilisation des tuyaux enterrés dans les projets d'irrigation de petite taille, est faisable du point de vue économique même en faisant abstraction des avantages indirects et non tangibles provenant de l'environnement. Le rapport traite seulement des projets spéciaux de l'ES recommandés pour la région du projet. Cependant, les résultats peuvent être généralisés et appliqués aux autres régions du pays. Copyright © 2001 John Wiley & Sons Ltd. [source] Interaction between phosphorus and biodegradable organic carbon on drinking water biofilm subject to chlorinationJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2010S.-K. Park Abstract Aims:, To examine whether phosphorus and biodegradable organic carbon interact to impact biofilm density and physiological function of biofilm-forming bacteria under conditions relevant to chlorinated drinking water distribution systems. Materials and Results:, The 2 × 2 factorial experiments with low and high levels of phosphorus and biodegradable organic carbon were performed on 4 -week-old drinking water biofilms in four separate pipe systems in the presence of chlorine. Experimental results revealed that biofilm heterotrophic plate count levels increased with the increase in biodegradable organic carbon concentration, showed no response to increases in levels of phosphorus and was not affected by interaction between phosphorus and biodegradable organic carbon. However, a significant positive interaction between phosphorus and biodegradable organic carbon was found to exist on biofilm mass and physiological function and/or metabolic potentials of biofilm communities; the effects of biodegradable organic carbon on biofilm mass and physiological function of biofilm-forming bacteria were accelerated in going from low to high level of phosphorus. Conclusions:, Biodegradable organic carbon was found to be the primary nutrient in regulating biofilm formation in drinking water regardless of the presence of chlorine. It can be therefore concluded that the removal of an easily biodegradable organic carbon is necessary to minimize the biofilm growth potential induced by the intrusion of phosphorus. Significance and Impact of the Study:, Phosphorus introduced to drinking water may interact with biodegradable organic carbon, thus leading to measurable impact on the biofilm formation. [source] Surrounded by mycobacteria: nontuberculous mycobacteria in the human environmentJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2009J.O. Falkinham Summary A majority of the Mycobacterium species, called the nontuberculous mycobacteria (NTM), are natural inhabitants of natural waters, engineered water systems, and soils. As a consequence of their ubiquitous distribution, humans are surrounded by these opportunistic pathogens. A cardinal feature of mycobacterial cells is the presence of a hydrophobic, lipid-rich outer membrane. The hydrophobicity of NTM is a major determinant of aerosolization, surface adherence, biofilm-formation, and disinfectant- and antibiotic resistance. The NTM are oligotrophs, able to grow at low carbon levels [>50 ,g assimilable organic carbon (AOC) l,1], making them effective competitors in low nutrient, and disinfected environments (drinking water). Biofilm formation and oligotrophy lead to survival, persistence, and growth in drinking water distribution systems. In addition to their role as human and animal pathogens, the widespread distribution of NTM in the environment, coupled with their ability to degrade and metabolize a variety of complex hydrocarbons including pollutants, suggests that NTM may be agents of nutrient cycling. [source] Automated concentration and recovery of micro-organisms from drinking water using dead-end ultrafiltrationJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2008E.A. Kearns Abstract Aims:, Concentration of pathogens diluted in large volumes of water is necessary for their detection. An automated concentration system placed online in drinking water distribution systems would facilitate detection and mitigate the risk to public health. Methods and Results:, A prototype concentrator based on dead-end hollow fibre ultrafiltration was used to concentrate Bacillus atrophaeus spores directly from tap water. Backflush was used to recover accumulated particulates for analysis. In field tests conducted on a water utility distribution system, 3·2 × 104,1·4 × 106 CFU ml,1 (6·1 × 106,3·0 × 108 CFU) were recovered from the filter when 2·9 × 107,1·0 × 109 CFU were spiked into the system. Per cent recovery ranged from 21% to 68% for flow volumes of 15,21 l. Tests using spore influent levels <10 CFU l,1 (spike < 1000 CFU) yielded 23,40% recovery for volumes >100 l. Conclusions:,B. atrophaeus spores at levels <10 CFU l,1 were concentrated directly from tap water using an automated dead-end hollow-fibre ultrafiltration system. Significance and Impact of the Study:, The prototype concentrator represents a critical step towards an autonomous system that could be installed in drinking water distribution lines or other critical water lines to facilitate monitoring. Recovered samples can be analysed using standard or rapid biosensor methods. [source] Assessment of bismuth thiols and conventional disinfectants on drinking water biofilmsJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2003F. Codony Abstract Aims: Biofilms in water distribution systems represent a far more significant reservoir of micro-organisms than the water phase. Biofilms are (i) resistant to disinfectants, (ii) nuclei for microbial regrowth, (iii) a refuge for pathogens, (iv) accompanied by taste and odour problems, and (v) corrode surfaces. The effects of the current strategies for disinfection of drinking water systems in large buildings (chlorination, copper and silver ionization, and hyper-heating) were compared with a new generation of bismuth thiol (BT) biocides. Methods and Results: Multispecies biofilms were treated with 0·8 mg l,1 of free chlorine, 400 and 40 ,g l,1 of copper and silver ions, respectively, at 55 and 70°C, and bismuth-2,3-dimercaptopropanol (BisBAL). Furthermore, the effect of combined heat and BisBAL on planktonic cell viability was examined in monoculture using Escherichia coli suspensions. Inactivation rates for BisBAL were similar to copper,silver ions, where the effects were slower than for free chlorine or temperature. The BisBAL effect on E. coli monocultures was augmented greatly by increasing temperatures. Conclusions: Like copper,silver ions, BTs show more persistent residual effects than chlorine and hyper-heating in water systems. BT efficiency increased with temperature. Like copper,silver ions, BT action is relatively slow. Significance and Impact of the Study: BT presents a new approach to containing water biofilms. BT action is not as rapid, but is more thorough than chlorine, and less caustic. BTs may also be more efficacious in hot water systems. At sub-minimum inhibition concentration levels, BTs uniquely inhibit bacterial exopolysaccharide, thereby retarding biofilm formation. Thus, the combination of bactericidal and residual effects may prevent slime build-up in hot water systems. [source] Aqueous chloramine diffusion into elastomersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Raja M. Nagisetty Abstract Aqueous chloramine diffusion into styrene butadiene rubber (SBR) and natural rubber was analyzed using approximate analytical and numerical solutions of Fick's second law of diffusion to develop long-term mass intake prediction curves. Diffusion coefficients were calculated for 1 mg/L chloramine concentration at three temperatures (23, 45, and 70°C) and also for 23°C at three chloramine concentrations (1, 30, and 60 mg/L). The reasonableness of using increased temperature and/or chloramine concentration to accelerate the diffusion process to obtain long-term information was discussed. For 1 mg/L chloramine concentration, the activation energy for the diffusion of chloramines into SBR and natural rubber were computed to be 51.13 and 77.29 kJ/mol, respectively. Also, concentration profiles were developed to understand the extent of penetration through the elastomer thickness over time and temperature. Considering the reports of elastomeric compound failure in chloramine disinfectant water distribution systems because of swelling, this study will be helpful in understanding the performance of the elastomeric compounds in the system. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Colonization of Legionella Species in Hotel Water Systems in TurkeyJOURNAL OF TRAVEL MEDICINE, Issue 6 2007Haluk Erdogan MD Background The goal of this study was to evaluate the prevalence of Legionella species in hotel water distribution systems in Alanya, Turkey, which is an important tourism center. Methods Water and swab samples were obtained from 52 Turkish hotels from August 2003 to September 2005. Water samples were collected in 100 mL sterile containers and were concentrated by membrane filters with a pore size of 0.45 ,m. Heat treatment was used to eliminate other microorganisms from the samples, which were then spread on buffered charcoal yeast extract , agar plates and glycine, vancomycin, polymyxin, cycloheximide agar plates. Cysteine-dependent colonies were identified by latex agglutination. Results In all, 491 water and swab samples were analyzed. The results of all samples were negative for Legionella in 16 (30.8%) hotels. Legionella species (92.5% of which were Legionella pneumophila) were detected in 93 (18.9%) of the samples. The most frequently isolated species were L pneumophila serogroups 6 (63.5%) and 1 (21.5%). ConclusionsLegionella pneumophila serogroup 6 was the most common isolate detected in Turkish hotel water systems in our study. The result of Legionella urinary antigen tests, which are the diagnostic tests most often used to identify legionnaires' disease, may be negative in people infected with L pneumophila serogroup 6. We suggest that clinicians should apply the whole spectrum of laboratory methods for the detection of legionnaires' disease in patients with pneumonia of unknown origin and history of travel to Alanya, Turkey. [source] Iron uptake is essential for Escherichia coli survival in drinking waterLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2006D. Grandjean Abstract Aims:, The aim of this study was to elucidate if the need for iron for Escherichia coli to remain cultivable in a poorly nutritive medium such as the drinking water uses the iron transport system via the siderophores. Methods and Results:, Environmental strains of E. coli (isolated from a drinking water network), referenced strains of E. coli and mutants deficient in TonB, an essential protein for iron(III) acquisition, were incubated for 3 weeks at 25°C, in sterile drinking water with and without lepidocrocite (, -FeOOH), an insoluble iron corrosion product. Only cells with a functional iron transport system were able to survive throughout the weeks. Conclusions:, The iron transport system via protein TonB plays an essential role on the survival of E. coli in a weakly nutritive medium like drinking water. Significance and Impacts of the Study:, Iron is a key parameter involved in coliform persistence in drinking water distribution systems. [source] Isotope applications in environmental investigations part II: Groundwater age dating and recharge processes, and provenance of sulfur and methaneREMEDIATION, Issue 2 2003Julie K. Sueker Measurement of the isotopic composition of solids, solutes, gases, and water complement standard hydrogeological investigation techniques by providing information that may not otherwise be obtainable. Groundwater age estimates determined from the decay of radio-isotopes or from groundwater concentrations of anthropogenic gases such as chlorofluorocarbons (CFCs) and sulfur hexafluoride (SF6) are used to verify flow regimes and constrain or calibrate hydrologic flow models. Groundwater recharge rates are estimated by measuring the concentrations or activities of a variety of isotopes including 2H, 3H, 18O, and 36Cl. Excess sulfur causes salinization of water supplies and acidification of precipitation, surface water, and groundwater. The wide range of sulfur isotopic compositions exhibited by different sulfur species and sources allows the application of sulfur isotopes to trace sources and fate of sulfur in the environment. Methane is a ubiquitous gas that has economic value when located in extractable reservoirs. Methane is also a greenhouse gas and is a potential explosion and health hazard when it accumulates in buildings and water distribution systems. The carbon and hydrogen isotopic composition of methane can be used to determine the provenance of methane, distinguishing between thermogenic and biogenic sources. The addition of isotopic analyses to environmental investigations can be a cost-effective means of resolving intractable issues. © 2003 Wiley Periodicals, Inc. [source] | |||||||||||||