ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1985.tb05650.x

出版商:Wiley    

年代:1985

数据来源: WILEY

摘要:

This article discusses the impact of President Reagan's tax proposals, which were released to the US Congress on May 28, 1985, on the ability of state and local governments to finance needed infrastructure improvements at reasonable cost. Topics covered include: accelerated cost recovery system, investment tax credit, tax‐exempt financing, and long‐term service contracts for tax‐exempt facilities.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1985.tb05651.x

出版商:Wiley    

年代:1985

数据来源: WILEY

摘要:

This discussion took place June 26, 1985, during the AWWA annual conference in Washington, D. C. Participants were: Joseph Calabro, manager of water quality and purification, Pennsylvania Gas and Water Co., Scranton, Pa.; John Cleasby, professor of civil engineering at Iowa State University, Ames, Iowa; William Kelley, water supply chief of the Michigan Health Department, Lansing, Mich.; John Kirner, water resources coordinator of the Tacoma Department of Public Utilities, Tacoma, Wash.; and Craig Vogt, deputy director of the criteria and standards division of the Office of Drinking Water, US Environmental Protection Agency, Washington, D.C. Wesley Pipes, chairman of the civil engineering department of Drexel University, Philadelphia, Pa., served as moderator of the panel

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1985.tb05652.x

出版商:Wiley    

年代:1985

数据来源: WILEY

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1985.tb05653.x

出版商:Wiley    

年代:1985

数据来源: WILEY

摘要:

Several large water utilities, including many in the Pacific Northwest, rely on watershed management, ongoing examination of water quality, and enhanced disinfection practices to maintain safe water instead of filtration. The authors base this article on their experience with the Seattle and Tacoma water systems in the state of Washington and conclude that mandatory filtration for all surface water systems does not seem to be justifiable

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1985.tb05654.x

出版商:Wiley    

年代:1985

数据来源: WILEY

摘要:

Water distribution system models are only as good as the data with which they are calibrated. Simply comparing predicted and observed pressures during normal use cannot ensure accuracy. Some tips for calibration are presented.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1985.tb05655.x

出版商:Wiley    

年代:1985

数据来源: WILEY

摘要:

A relatively new concept in the United States, the two‐stage filtration process incorporates an initial bank of coarse filters, followed by a bank of final filters that are normally operated at a high filtration rate. Pilot studies showed that two‐stage filtration is an attractive alternative to either conventional treatment or direct filtration, depending on the quality of the raw water. If the raw water frequently exhibits high turbidity or presents taste and odor problems, type 1 two‐stage filtration, which includes flocculation and settling, should be considered as the treatment alternative. The type 2 two‐stage process, involving neither flocculation nor settling, is suggested for cases in which the raw water quality is good enough to allow direct filtration.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1985.tb05656.x

出版商:Wiley    

年代:1985

数据来源: WILEY

摘要:

Full‐scale municipal slow sand filters at seven sites in the Syracuse, N.Y., area were monitored before, during, and after filter scraping to verify the presence or absence of a ripening period, to determine the filter run length, and to quantify the labor and material required for scraping and resanding operations. Results showed some evidence of a ripening period, ranging from 6 h to 2 weeks, in four of the 10 operations monitored. The presence or absence of a ripening period did not seem to be related to the use of prechlorination, to water temperature, to scraping methodology, or to frequency of filter maintenance. The factor that seemed to have the most significant effect on the quality of the filtrate was the amount and nature of the particulate matter present in the raw water.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1985.tb05657.x

出版商:Wiley    

年代:1985

数据来源: WILEY

摘要:

Study of the water of Chichester Dam, operated by the Hunter District Water Board in New South Wales, Australia, indicated that the supply could possibly be treated by direct filtration—at capital and operating costs well below those for conventional treatment. Extensive pilot‐plant testing carried out to determine the feasibility of direct filtration included optimization of the media and of the chemical system, evaluation of declining‐rate versus constant‐rate filtration, and use of artificially manufactured “dirty water.” The treatment process selected as a result of these pilot studies was constant‐rate direct filtration, with mechanical in‐line chemical mixing and no flocculation.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1985.tb05658.x

出版商:Wiley    

年代:1985

数据来源: WILEY

摘要:

Biological activity within the sand bed had the strongest influence on removal efficiency of total coliform bacteria by slow sand filtration, as determined by six pilot filters (shown above). Temperature, sand bed depth, and sand size also had strong influence.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1985.tb05659.x

出版商:Wiley    

年代:1985

数据来源: WILEY