SURFACE WATER SOURCE

Supply of MU water for a medium-pressure (450 psig) WT boiler, from a surface water source with very variable suspended solids and hardness (sugar refinery, South Africa). The process used is a. carbonate removal using hot-lime precipitation softening coupled with silica adsorption by magnesia addition b. clarification in anthracite filters and c. cation ion-exchange for the balance of hardness removal. 

Wnuk M, Kelley R, Breuer G, et al. 1987. Pesticides in water samples using surface water sources. Des Moines, IA Iowa Dept, of Natural Resources and Iowa University Hygienic Laboratory. PB88-136916. 

Dichlorobenzene has also been found in 13% of the drinking water samples from U.S. surface water sources. The surface water samples measured contain about 0.008-154 ppb of... 

The relative contributions of the exposure routes and sources are as follows. For persons exposed to isophorone in the workplace, total doses will probably be substantially higher than those exposed only to ambient air and drinking water, and their inhalation and dermal exposures for the occupationally exposed can be assumed to result exclusively from the workplace exposures. Inhalation and dermal exposure for persons not exposed to isophorone in the workplace will most likely result from showering or bathing, but only in locations that receive their drinking water from contaminated surface water sources. These exposures are expected to be very small. In locations that do not have the potential for isophorone in the drinking water, any ingestion, inhalation, or dermal exposure is unlikely. 

As mentioned earlier, surface water sources forming part of an estuarine system are subject to tremendous swings in chloride concentration. Levels of 1000 ppm Cl or more are not unusual, which imposes serious constraints, plus corrosion and deposit control problems when used as makeup for cooling systems that may normally operate at 3 to 4x cycles of concentration. Contingency plans are necessary. 

Nelson, H. and R.D. Jones (1994). Potential regulatory problems associated with atrazine, cyanazine, and alachlor in surface water source drinking water. Weed. Technol., 8 852-861. 

A population-linked database was developed to assess exposure to the herbicides atrazine and simazine in the drinking water of community water systems (CWS) fed by groundwater and surface water sources in 32 major-use states. These states represent about 99% of the annual atrazine and simazine use in the United States. Herbicide concentration and population data from 1993 through 2000 were paired for each water system and then aggregated to construct state and multistate exposure profiles. 

Atrazine was not detected in 92.3% of the samples (Table 29.5). As expected, there were more nondetections in groundwater than in surface water sources. 

Three of the 28280 assessed systems had multiyear average concentrations above 3.0ppb for the 8-year period (Table 29.5). Each obtained raw water from an impounded (reservoir) surface water source. The multiyear average for atrazine concentrations in these systems ranged from 3.30 to 3.41 ppb. 

There are limited monitoring data for cyanazine and propazine from CWS with groundwater and surface water sources. USEPA (1989a) has established lifetime HALs of 1.0 and lO.Oppb for cyanazine and propazine, respectively. 

From time immemorial, surface water played a pivotal role to human life as a source of drinking water because of its easy access compared with any other water source. A few decades ago, the use of contaminated surface water sources was found to contribute to the transmission of waterborne bacterial diseases. Thus, a paradigm shift in water usage from surface to groundwater was inevitable. 

Malcolm Pirnie, Inc and HDR Engineering, Inc. Guidance Manual for compliance with the filtration and disinfection requirements for public water systems using surface water sources for USEPA (contract No 68-01-6989). Denver American Water Works Association, 1991. 

Spent or exhausted resin has been used on occasion to filter RO influent water. These filters are designed to remove silt and reduce SDI from surface water sources. All evidence to the effect of such... 

Tables 9.2 and 9.3 list the recommended feed water and concentrate flow rates, respectively, as functions of feed water source quality.1 Higher feed water flow rates result in water and its contaminants being sent to the membrane more rapidly, leading to faster rates of fouling and scaling. As Table 9.2 shows, an RO operating on a well water source can have a feed flow rate as higher as 65 to 75 gpm per pressure vessel, while a surface water source RO should not exceed 58 to 67 gpm per pressure vessel. The well water RO would require 12% fewer pressure vessels than the surface water RO.

For this low hardness, surface water case, the antisealant operating cost is lower than that for the softener. Again, the affect of the softener on improved membrane performance is not known and should be considered for this surface water source. 

Approximately one-half of the water contained in land is in the upper 1 km of the Earth, and the other half is in the next 4 km, as deep groundwater. Much of the surface water comes from precipitation. When the precipitation rate exceeds the infiltration rate into the soil, an excess of water builds up on the soil surface and moves overland as surface runoff, contributing to the streams, rivers, and other surface water sources. Part of the surface water is a contribution from spring water (i.e., groundwater that flows out to the surface owing to a physical condition that obstructs its flow under the Earth, or when the water table intersects the surface). 

Pit latrines are at least 30 meters from any ground-water source and the bottom of any latrine is at least 1.5 meters above the water table. Drainage or spillage from defecation systems must not run towards any surface water source or shallow groundwater source. 

Measures to prevent transmission include proper disposal of feces, wastewater treatment, and a filtration step before chlorination in water treatment plants that draw from surface water sources. Cooking kills the cysts in contaminated foods and boiling will make water safe for use. For backpackers who walk through the wilderness, iodine has been shown to be a better disinfectant for giardia cyst than chlorine. It should be emphasized that of all the methods of preventing contamination from the cyst, a properly designed and operated water filtration plant is the best line of defense in drinking water supplies. 

David J. Hiltebrand, Inc. (1990). Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems Using Surface Water Sources. Am. Water Works Assoc., Denver. 

Higher concentrations of As tend to be found more in groundwater than in surface water sources of drinking water therefore, the emphasis of this paper is on the geochemical processes that affect As transport in groundwater. However, many of the processes discussed are also applicable to surface waters and the variably saturated zone above the groundwater table. 

The contact time multiplied by the concentration (mg/L) of residual chlorine in the water is the calculated CT value for the system. Proven inactivation of Giardia and viruses are correlated to calculated CT values in US EPA s Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems Using Surface Water Sources (28). Appendix B contains excerpts from the CT tables in the manual. 

This section summarizes the field studies performed to compare the efficiencies of dechlorination chemicals under identical conditions to evaluate the chemical of choice for various dechlorination applications (18,19). The field tests were conducted at Tacoma Waters, WA, Portland Bureau of Water Works, OR, and East Bay Municipal Utility District (EBMUD), CA. Six dechlorination chemicals were used in solution, tablet, or powder form in these tests (Table 3). In the Tacoma and Portland studies, a 1 % solution of the dechlorination chemicals were introduced into water released from a hydrant. The field studies evaluated the rate of dechlorination, effect of overdosing, and concurrent water quality impacts when stoichiometric or twice the stoichiometric amounts of dechlorination agents were added. In the EBMUD dechlorination studies, bags, or dispensers containing tablets or powders of dechlorination chemicals were placed in the flow path of hydrant water. At all three sites, the water used for the test originated from surface water sources rather than from groundwater sources. Table 3 summarizes the chemicals, forms and dosing rates used in these studies. 

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