Suchergebnisse

The health risk associated with contamination of drinking water is of permanent concern for public and the professional communities. In recent years considerable advances have been made in understanding the problem. This volume reviews selected issues of drinking water quality and treatment written by leading authorities in their respective fields. One of the main features of the volume is its emphasis on the complementary tasks of chemists, biologists, toxicologists, engineers, legislators and politicians in combatting drinking water contamination. The second part of this volume includes analysis of organic micropollutants, toxicity tests for assessing drinking water quality, the issue of algae toxins, vulnerability of groundwater to contamination from agricultural activities and quality changes due to application of ozone and chlorine dioxide

The objective of this paper was to assess bacteriological quality of drinking water in a peri-urban area located in the Metropolitan Region of São Paulo, Brazil. A total of 89 water samples were collected from community plastic tanks and 177 water samples from wells were collected bimonthly, from September 2007 to November 2008, for evaluating bacteriological parameters including: Escherichia coli, Enterococcus and heterotrophic plate count (HPC). Clostridium perfringens was investigated in a subsample (40 samples from community plastic tank and 40 from wells). E. coli was present in 5 (5.6%) samples from community plastic tanks (2.0 - 5.1x104 MPN/100mL) and in 70 (39.5%) well samples (2.0 - 8.6x104 MPN/100mL). Thus, these samples were not in accordance with the Brazilian Regulation. Enterococcus was detected in 20 (22.5%) samples of the community plastic tanks (1 to 79 NC/100mL) and in 142 (80.2%) well samples (1 to >200 NC/100mL). C. perfringens was detected in 5 (12.5%) community plastic tanks samples and in 35 (87.5%) wells samples (2.2 to >16 MPN/100mL). HPC were above 500 CFU/mL in 5 (5.6%) waters from community plastic tanks. In wells samples, the HPC ranged from <1 to 1.6x104 CFU/mL. The residual chlorine did not attend the standard established in the drinking water legislation (0.2 mg/L), except in 20 (22.5%) samples. These results confirm the vulnerability of the water supply systems in this peri-urban area what is clearly a public health concern.

The microbiological quality of drinking waters was evaluated in northwestern Portugal between 1996 and 2005, according to the guidelines of European Directives of 1980 and 1998. Out of the 21,630 microbiological analyses done, the percentage of treated and nontreated waters analyzed were similar, but the fraction of conforming samples were higher for treated (74.2%) than for nontreated (37.8%) water. The microbiological quality of potable water improved throughout the study period, particularly in the last 2 yr, when drinkable water reached 70%. The increase during the last 2 yr is a result of at least two different causes: an increase in the use of treated waters and the change in the legislation (1998/83 EC Directive). Although the number of treated waters has increased, the nonconforming treated water is still very high (25%) even when evaluated under the 1998/83 EC Directive. ; published

This Guidance Manual has been produced by the members of the Wat-Qual consortium, funded by the European Union's Horizon 2020 research and innovation programme under grant agreement No. 778136. The manual provides a series of fact sheets covering the latest understanding of drinking water quality management in water distribution systems, covering the topics of: - flushing - disinfection - maintenance and repairs

ABSTRACTPublic understanding of water quality is obtained primarily from the extensive media coverage of problems. This has contributed to a distrust of the water supply industry and of specific experts in this field. It is therefore important that the basis of standards for both microbiological and chemical parameters is absoulutely clear and scientifically defensible, since these are the yardsticks against which quality and safety will be judged. They are also the reference point from which political decisions on standards must be made.It is also important that the public is given some understanding of the comparative risks involved and that a proper balance is struck between maintaining microbiological quality and achieving chemical standards, particularly for disinfection by‐products. Without this, the demand for more stringent standards in a search for absolute safety will result in more costly water, while standards approach the unachievable.

Urbanization during last centuries has led to growth of the cities worldwide and centralized drinking water supply system (DWSS) is vital to ensure healthy and evolving society. The aim of DWSS is to supply clean and safe drinking water to every point of the DWSS. The drinking water must satisfy chemical, biological and aesthetic requirements included in legislation of every state or country. In most of the cases drinking water quality meets the requirements straight after the treatment. However there are numerous cases when consumers have got sick by using poor quality drinking water. Pipe breaks, bacterial regrowth, maintenance and construction works of DWSS, corrosion of pipelines, sewerage cross connections, failure of water purification plant, deliberate drinking water contamination might cause water quality deterioration at the consumption point (Lee et al., 2012). Although the legislation in modern countries says that random "grab" samples must be taken to monitor the drinking water quality, the continuous monitoring of drinking water quality is essential to deliver safe water to consumer. Moreover, conventional microbiology testing methods can take several hours or days, which would lead to long response time of water authorities in case of contamination. That is the reason why the on-line monitoring of drinking water gets more popular in most developed countries. The use of on-line monitoring can reduce response time to several minutes or even seconds. The aim of this study was to investigate the ability of on-line sensors to detect the daily fluctuations of drinking water quality and impact of extended internal water network on drinking water quality.

"Drinking Water: Quality Control, Distribution Systems and Treatment focuses on some of the technologies involved in water treatment processes, such as adsorption, co-precipitation, flocculation, and coagulation. The authors emphasize the newest easy processes, inadequacies, and prospects of drinking water treatment. In one study, a simple effective intervention for biochanin A in influent water using ZSM-5, a nano-porous crystalline zeolite, is described. In closing, a Sphingomonas paucimobilis strain isolated from an Indian drinking water system was evaluated for its ability to co-aggregate and form mixed biofilms with Salmonella typhimurium, Shigella flexneri, and Escherichia coli O57:H7"--

SUMMARYAvailable national guidelines for disinfection practice, and for the examination of bacteriological quality, are reviewed, together with the legislative requirements of the EC 'Drinking Water'Directive. Problems of impracticability, vagueness, and ambiguity are identified.Experience of the maintenance of bacteriological quality in large, lowland, surface water and ground‐water supply areas is given with reference to the behaviour of disinfectant residuals, trihalomethanes, nitrite, and aesthetic parameters. The way forward in terms of the management of distribution systems and water treatment is discussed.