摘要:

This article continues a discussion of the revision of the USEPA drinking water regulations begun in the December 1984 issue of OpFlow. There are many contaminants for which Maximum Contaminant Levels (MCLs) may be changed. This is due to experience gained in implementing the regulations since 1977, new scientific and health data, and advances in analytical capability. In addition, new contaminants probably will be added and others dropped. Specific contaminant considerations which are dealt with in this article include: coliforms, turbidity, giardia lamblia, viruses, legionella, standard plate count, and inorganic chemicals.

ISSN:0149-8029    

DOI:10.1002/j.1551-8701.1985.tb00371.x

出版商:Wiley    

年代:1985

数据来源: WILEY

摘要:

Questions in this Certification Corner deal with the following subjects: lime‐soda ash softening, cast‐iron pipe scale, backflow prevention, hydrologic cycle, methyl orange, water treatment plant effluent, and well construction.

ISSN:0149-8029    

DOI:10.1002/j.1551-8701.1985.tb00372.x

出版商:Wiley    

年代:1985

数据来源: WILEY

摘要:

Every public and private water utility is responsible for distributing the costs of system ownership, operation and maintenance among all of its users in a reasonable and equal manner. In order to accomplish this, the water utility must first determine what to base the charges on and how frequently to apply the charges. The Butler County Water and Sewer Department, which serves a very unstable area that suffers form both a high growth rate and a high changeover rate, decided to investigate various billing and meter reading frequency schedules as a result of an increasing rate of uncollectible revenues. This article discusses the steps the Butler County Water Service Area went through in determining the frequency of meter reading and billing that would best serve their needs.

ISSN:0149-8029    

DOI:10.1002/j.1551-8701.1985.tb00373.x

出版商:Wiley    

年代:1985

数据来源: WILEY

摘要:

Lime‐soda ash softening is used in most larger treatment plants to remove dissolved minerals, especially calcium and magnesium, which cause hardness in water. When lime and soda‐ash are added, the hardness‐causing minerals form nearly insoluble precipitates. These precipitates are removed by the conventional processes of coagulation/flocculation, sedimentation, and filtration. The following types of lime‐soda ash processes are discussed: conventional lime‐soda ash treatment; excess‐lime treatment; split treatment; and caustic soda treatment. This article is adapted from the AWWA publication, Introduction to Water Treatment, Module 5, Softening.

ISSN:0149-8029    

DOI:10.1002/j.1551-8701.1985.tb00374.x

出版商:Wiley    

年代:1985

数据来源: WILEY

摘要:

Many municipal and private water systems use 3/4 through 2‐in. (19mm through 50‐mm) handwheel gate valves to isolate sections of their water service systems. The most common problem encountered with such valves is leakage past the valve stem packing. Because of the high cost associated with the excavation of paved streets, it is not uncommon for water departments to permit such leakage to continue until it becomes severe. The handwheel gate valve repair tool allows the waterworks operator to replace broken handwheels and tighten leaking valve stem packing nuts without having to dig up the valve box. This article gives information on constructing such a tool for an approximate cost of $5070.

ISSN:0149-8029    

DOI:10.1002/j.1551-8701.1985.tb00375.x

出版商:Wiley    

年代:1985

数据来源: WILEY