ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1994.tb06228.x

出版商:Wiley    

年代:1994

数据来源: WILEY

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1994.tb06229.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

In a case of interest but without wide precedential effects, a New York trial court has upheld consumption‐based water rates set by the New York City Water Board. Decisions of trial courts generally have impact only within the limited jurisdiction of the court issuing the decision. Therefore, this decision issued by a New York State Supreme Court‐‐a trial court, not an appellate court‐‐is reported only as a matter of general interest. A 1984 state law established the New York City Water Board, which had power to set water and sewer rates. The board mandated a universal metering program to promote rate equity and water conservation. The Rent Stabilization Association, an organization of 25,000 owners of rent‐stabilized apartment buildings in the city, challenged the program, claiming it created undue monetary hardship.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1994.tb06231.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

The US Environmental Protection Agency (USEPA) is required to regulate sulfate under the 1986 Safe Drinking Water Act (SDWA) amendments, and a rule has been under development for several years. The agency decided to reconsider a regulation proposed for sulfate under Phase V, which has been previously reviewed. Following deferral of the Sulfate Rule proposed under Phase V, USEPA's sulfate workgroup proceeded to evaluate alternative options for its regulation. Draft regulatory and preamble language was prepared for a new proposed rule. This material was eventually released outside the agency and has been referred to as a “preproposal.” This article is a summary of the preproposal.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1994.tb06233.x

出版商:Wiley    

年代:1994

数据来源: WILEY

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1994.tb06234.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

If the SDWA is reauthorized so USEPA can more selectively determine which contaminants are regulated, the result will be greater health protection benefits per dollar spent.This article examines the extent to which the federal drinking water program is meeting its public health protection goals and reviews the costs regulations imposed on society at a time when the Safe Drinking Water Act (SDWA) is under review for reauthorization by Congress. Under the 1986 amendments, USEPA has promulgated seven significant rule‐making packages covering more than 70 contaminants. The regulatory record reveals a high degree of variability in costs and risk reductions associated with these rules. For example, nearly 99 percent of the program's total carcinogenic risk reduction is attained for about 60 percent of the total regulatory costs for carcinogens because of the maximum contaminant levels established for 10 contaminants. This means about 40 percent of carcinogen‐related regulatory costs are achieving an insignificant 1 percent of cancer risk reduction. If the regulations were focused on systems serving more than 500 people, almost 90 percent of total carcinogenic health risk reduction benefits could be realized at only 43 percent of the costs.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1994.tb06235.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

Although the difference in their efficiencies was frequently small, iron‐oxide‐coated sand outperformed uncoated sand as a filter medium in almost all cases.Plain sand was compared with iron‐oxide‐coated sand as a medium for filtration. The coated sand has a positive surface charge at neutral pH, whereas uncoated sand is negatively charged under similar conditions. The influent to the filters contained either latex particles, which were negatively charged in all solutions investigated, or ferrihydrite particles, which were negatively charged at pH>5 but positively charged at lower pH values. The coated medium outperformed the uncoated one in most experiments, a result that is consistent with expected electrostatic interactions.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1994.tb06236.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

In laboratory and field studies, a two‐stage buoyant coarse media flocculator provided settled water turbidities<2 ntu at loading rates as high as 12 gpm/sq ft.A new type of coarse media flocculator, using buoyant media instead of the heavier gravel in order to facilitate cleaning, was evaluated in laboratory and field studies. The results indicate that a two‐stage buoyant coarse media (BCM) flocculator provided effective treatment at higher loading rates and shorter residence times than are typically employed in designing mechanical flocculators. Source‐water quality and coagulant chemistry directly influenced flocculator performance and dictated the type of flocculator configuration selected. Tapering velocity gradients in the first‐stage flocculator enhanced performance. The authors recommend that additional studies be performed to develop reliable design and operating criteria for full‐scale BCM flocculators.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1994.tb06238.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

Results showed that the synthetic adsorbent studied is more efficient than GAC in removing trichloroethene from a groundwater—as well as being more resistant to fouling by natural organic matter.The performance of a synthetic adsorbent in removing trichloroethene (TCE) from a groundwater containing natural organic matter (NOM) was compared with that of granular activated carbon (GAC). Adsorption equilibrium, kinetic, and pilot‐plant experiments were used to compare the adsorbents. Adsorption isotherm studies showed that the synthetic adsorbent had three to four times more TCE capacity than GAC over a TCE concentration range of 10‐2,000 μg/L. When preexposed for 24 weeks to a groundwater containing NOM, the synthetic adsorbent showed an average 12 percent loss in capacity compared with the single‐solute isotherm performed on the virgin adsorbent; GAC showed an average 35 percent loss in its virgin capacity for a preexposed time of only 10 weeks. Rapid small‐scale column tests and model calculations predicted pilot‐plant effluent profiles for the synthetic adsorbent. The pilot‐plant data confirmed that the synthetic adsorbent is more efficient than GAC in removing TCE.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1994.tb06239.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

Based on the most conservative estimates, computers predicted that the interval between carbon replacements could safely be extended to nine months for 50 percent of the filters.Nearly 1,000 point‐of‐entry granular activated carbon (GAC) filters are efficiently removing ethylene dibromide (EDB) from contaminated groundwater throughout Florida. This article discusses the design, performance, and operational problems of the filters and assesses the possibility of extending the interval between GAC replacement from the current six months. Few breakthroughs have occurred in these filters, and most were caused by desorption during periods of sharp decreases in well‐water EDB concentrations. Because GAC loading data from the literature described the program data very well, they were used in conjunction with the equilibrium column model to predict the performance of the program's filters for different GAC replacement periods. Based on the most conservative estimates, maintenance for 50 percent of the filters could be extended to every nine months.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1994.tb06240.x

出版商:Wiley    

年代:1994

数据来源: WILEY