ISSN:1747-6585    

DOI:10.1111/j.1747-6593.1990.tb01460.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The groundwater resources of the Lee Valley Water Company have been examined in a joint study with the University of Birmingham. The Company is modifying its operating policy to make maximum use of the groundwater resources, which has involved the development of new methods of estimating the reliable output of the groundwater sources under differing conditions. The technology transfer involved in the project has enabled the Company to gain a greater understanding of the operation of its sources, and the University has modified existing techniques so that they are of greater practical use.

ISSN:1747-6585    

DOI:10.1111/j.1747-6593.1990.tb01461.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The Water Authorities Association guide ‘Sewers for Adoption’ has achieved considerable success in unifying practice and establishing well‐understood and recognized standards for the design and construction of sewers by developers under Section 18 of the Public Health Act 1936. However, the supervision provided by the adopting authorities — particularly in relation to supervision fees — has been an area of dispute for some time.The Construction Industry Research and Information Association (CIRIA) has recently completed a study on the optimum levels of supervision for sewer construction. The study included a national survey on the nature and extent of problems occurring during the course of Section 18 work and the supervision practices presently being undertaken. The study puts forward recommendations on the nature and timing of periodic inspections undertaken during construction. Several specific problem areas are discussed, ranging from measures required to ensure that design submissions are of an adequate standard, to the timing of any pre‐adoption closed‐circuit television inspection. This paper draws upon the contents of the report and discusses some of the principal findings and recommendations

ISSN:1747-6585    

DOI:10.1111/j.1747-6593.1990.tb01462.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Historically, typhoid and cholera are well‐recognized waterborne infections. Advances in laboratory techniques over the past 20 years have enabled a wide range of other faccally‐excreted bacteria, viruses and protozoa to be identified as causing gastrointestinal infections. Record outbreaks are referred to where some of these micro‐organisms have been spread by the contamination of drinking water, either at source or during distribution. This has usually happened when the water was untreated, or where there have been failures of the disinfection process or breaches in the integrity of the distribution system. Recent waterborne outbreaks of cryptosporidiosis have underlined the importance of adequate filtration in the prevention of waterborne transmission of this protozoon, the oocysts of which are completely resistant to the levels of chlorine that can be attained in water treatment practice. An outline is given of the current processes by which pathogenic micro‐organisms are excluded from drinking‐water supplies; their potential deficiencies for dealing with some of the ‘newer’ waterborne pathogens are a

ISSN:1747-6585    

DOI:10.1111/j.1747-6593.1990.tb01463.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Workers in the water industry are sometimes exposed to infectious micro‐organisms, particularly during the treatment and disposal of sewage. There is a legal requirement for water companies to appraise the degree of risk to which employees are exposed and then take appropriate action to minimize such risks. This is accomplished, to a large extent, by first understanding how infectious diseases are spread, and then devising safety practices to minimize occupational exposure to pathogenic micro‐organisms. Examples are given of types of communicable disease potentially associated with drinking water treatment (Legionnaires' disease and leptospirosis), as well as sewage treatment (viral gastroenteritis, AIDS and hepatitis B). The degree of perceived occupational risk associated with these pathogenic micro‐organisms is discussed along with preventative measures that can be implemented to minimize actual risk. There is no justification for enhanced immunization of water industry empl

ISSN:1747-6585    

DOI:10.1111/j.1747-6593.1990.tb01464.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The use of river corridor surveys (RCS) prior to major river maintenance works is now widely accepted within the water industry as a means of integrating the requirements for nature conservation with river‐management practices. This paper outlines the audit procedures introduced by the National Rivers Authority (NRA), Wessex Region.The introduction of follow‐up or audit surveys in 1988 allowed an assessment of the effectiveness of RCS in protecting and enhancing habitats. The method and results of the audit are discussed, confirming the usefulness of audit in ensuring success in the most cost‐effective manner. The audit also identified training needs and failures in implementing enhancement recommendations. Audit has led to a more consistent standard of environmentally‐sensitive maintenance work. A revised method for audit surveys is d

ISSN:1747-6585    

DOI:10.1111/j.1747-6593.1990.tb01465.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Effluent quality implications of bulking control with chlorine in activated‐sludge treatment have been studied on laboratory scale. Batch chlorination of sludge samples led to the formation of trihalomethanes, mainly as chloroform (in hundreds of ùg/l) and even more non‐specified organohalogens. Most organohalogens were formed from substances in the liquid effluent, and fewer out of the sludge solids. The presence of sludge lowered the concentration of extractable trihalomethanes in the effluent. Continuous chlorination in a laboratory‐scale activated‐sludge plant did not produce measurable quantities of any organohalogen c

ISSN:1747-6585    

DOI:10.1111/j.1747-6593.1990.tb01466.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

North West Water has evaluated several automatic coagulation control systems covering a range of raw waters and treatment facilities.The experiences have shown that streaming‐current type systems are effective in controlling coagulant dose automatically, provided that appropriate plant conditions exist. In particular, rapid fluctuations in flow or poor mixing of chemicals can lead to unstable signals. Recent investigations indicate that for some waters streaming‐current voltage is sensitive to small changes in pH, and precise control of pH is therefore necessary.The main observed benefits have been treated water of a more consistent high quality, together with improved security of service, as the systems will respond reliably and effectively over long periods. Significant savings in coagulant usage can be obtained in certain ca

ISSN:1747-6585    

DOI:10.1111/j.1747-6593.1990.tb01467.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Much attention has been focused on the need for sewer renovation and rehabilitation of old sewerage systems, but age is not always the reason for sewer failure. Serious problems of performance have also been encountered on sewerage schemes less than 10 years old. This paper considers the problems of groundwater infiltration into new foul sewers, and suggests that deficiencies might exist in some aspects of modern sewer design and construction.Infiltration is most frequently observed at sewer joints. Results are presented of laboratory tests which show the ability of flexible fixed‐ring joints on clay sewers to withstand both internal and external pressures. Damaged polyester fairings on the spigots of these pipes can act as one‐way valves, and massive infiltration may result. The standard site water test is shown to be inadequate in detecting some of these types of defect which may result from damaged pipes or poor workmans

ISSN:1747-6585    

DOI:10.1111/j.1747-6593.1990.tb01468.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Precast concrete blocks can be used as erosion protection to a surface subjected to high‐velocity water, for example a dam spillway.The paper describes model testing carried out on flat and wedge‐shaped blocks in a purpose‐designed facility at the University of Salford, where an open channel discharge intensity of 0.5 m2/s can be accelerated to a velocity of 7.5 m/s.The failure modes of tied and untied flat concrete blocks have been investigated under different laying and bedding conditions. The model results are compared to the findings from prototype studies. Results from experiments on wedge‐shaped blocks of a Soviet design are also presented and confirm the Russian experience that the wedge shape is inherently stable at large discharges, a block of 100‐m thickness being stable under a discharge intensity o

ISSN:1747-6585    

DOI:10.1111/j.1747-6593.1990.tb01469.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY