Issues in Potable Reuse The Viability of Augmenting Drinking Water Supplies with Reclaimed Water (1998) / Chapter Skim
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1 Reclaiming Wastewater: An Overview
1 Reclaiming Wastewater: An Overview
Pages 14-44
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From page 14... ...
These "potable reuse" projects are made possible by improved treatment technology that can turn municipal wastewater into reclaimed water that meets standards established by the Safe Water Drinking Act. However, questions remain regarding how much treatment and how much testing are necessary to protect human health when reclaimed water is used for potable purposes.
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From page 15... ...
This report should help communities considering potable reuse make decisions that will protect the populations they serve. Some of the issues relate to similar concerns for drinking water sources that receive incidental or unplanned upstream wastewater discharges.
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From page 17... ...
And Chapter 6 evaluates reliability and quality assurance issues for potable reuse projects. SELECTION OF DRINKING WATER SOURCES Some public health authorities have been reluctant to allow or support the planned augmentation of water supplies with reclaimed municipal wastewater under any circumstances, subscribing to the maxim that only natural water derived from the most protected source should be used as a raw drinking water supply.
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From page 18... ...
Communities looking for new water sources must examine a number of options, including water conservation, nonpotable reuse, and investing more money in the treatment of water supplies that are of poorer quality but more readily available. Most communities will readily pay a premium to obtain a pristine supply for their drinking water.
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From page 20... ...
The utility might identify potential contaminants of concern by surveying the industrial inputs into the wastewater, examining the wastewater for chemical constituents broader than those represented by drinking water standards, and/or using toxicological testing methods to ensure that the product water does not contain substantial concentrations of chemicals whose toxicological properties have not been established. TYPES OF WATER REUSE When discussing the reuse of treated municipal wastewater for potable purposes, it is useful to distinguish between "indirect" and "direct" potable reuse and between "unplanned" and "planned" potable reuse.
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From page 21... ...
With planned indirect potable reuse and direct potable reuse, the wastewater is treated to a much higher degree than it would be were it being discharged directly to a surface water without specific plans for reuse. The wastewater generally is first treated as it would be in a conventional municipal wastewater treatment plant, then subjected to various advanced treatment processes.
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From page 22... ...
According to measures of identifiable contaminants, water treated in this manner is often of better quality than some polluted surface waters now used as TABLE 1-1 Constituent Removal by Advanced Wastewater Treatment Processes Principal Type of Removal Description Wastewater Function of Process Treateda Suspended solids removal Filtration EPT, EST Microstrainers EST Ammonia oxidation Biological Vitrification EPT, EBT, EST Nitrogen removal Biological vitrification/ EPT, EST denitrification Nitrate removal Separate-stage biological EPT + Vitrification denitrification Biological phosphorus Mainstream phosphorus RW, EPT removal removalb Sidestream phosphorus RAS removal
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From page 23... ...
Microorganism removal is also accomplished by any of several chemical disinfection processes (e.g., free C12, NH2C1, C1O2, 03) , but these are not usually considered as advanced wastewater treatment processes.
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24 be.
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From page 25... ...
HISTORY OF PLANNED POTABLE REUSE AND ITS MOTIVATION Direct potable reuse is not currently approved for use in U.S. water systems.
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From page 26... ...
In the Washington, D.C., area, the wastewater-contaminated Potomac River Estuary was evaluated as a potential source of drinking water in an extensive study conducted from 1980 to 1983 by the U.S. Army Corps of Engineers and authorized as part of the Water Resource Development Act of 1974 (see Box 1-1~.
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From page 27... ...
, in the early 1960s using surface percolation of blends of captured storm water, imported water, and treated wastewater in unlined river channels or specially constructed spreading basins (Nellor et al., 1984, 1995~. In 1972, Orange County Water District in Fountain Valley, California, began operation of Water Factory 21 (see Box 1-2)
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From page 28... ...
In West Texas, the Fred Hervey Water Reclamation Plant began operation in 1985 as a wastewater treatment facility incorporating advanced treatment processes designed for recycling wastewater from the northeast area of E1 Paso back to the Hueco Bolson aquifer, which supplies both E1 Paso, Texas, and Tuarez, Mexico. This artificial recharge project is necessary to protect the freshwater aquifer from depletion and salt water intrusion.
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From page 29... ...
Planned augmentation of surface water supplies with reclaimed water is being investigated in both California and the eastern United States for different reasons. San Diego is actively investigating the feasibility of augmenting its general water supplies with reclaimed municipal wastewater because of the high costs of importing water from other parts of the state and the lack of local water sources (see Box 1-6~.
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From page 30... ...
Since 1978, the Upper Occoquan Sewage Authority (UOSA) , in northern Virginia, has discharged reclaimed wastewater to the upper reaches of the Occoquan Reservoir, which serves as the principal water supply source for approximately one million people.
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From page 31... ...
In Arizona, regulations addressing ground water recharge with treated wastewater are independent from the state's reuse criteria. Federal Guidelines EPA's guidance manual on water reuse, though not a formal regulatory document, provides recommendations for a wide range of reuse practices, including indirect potable reuse by ground water recharge or surface water augmentation, that should be useful to state agencies in developing appropriate regulations.
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From page 32... ...
32 ISSUES IN POTABLE REUSE TABLE 1-2 EPA Suggested Guidelines for Reuse of Municipal Wastewater Type of Reuse Treatment Reclaimed Water Qualitya Ground water recharge by spreading on ground above potable aquifers Ground water recharge by injection into potable aquifers · Site-specific · SecondaryC and disinfections (minimum) · May also need filtrations and/or advanced wastewater treatmentf · SecondaryC · Filtratione · Disinfectiond · Advanced wastewater treatmentf · Site-specific · Meet drinking water standards after percolation through vadose zone Includes, but is not limited to, the following: · pH = 6.5-8.5 · Turbidity < 2 NTU' · No detectable fecal coliforms per 100 mlj, k · Residuall 2 1 mg/liter C12 · Meet drinking water standards
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From page 33... ...
· The reclaimed water should to extraction be retained underground for wells; may vary depending on site-specific conditions at least 1 year prior to withdrawal ·Monitoring wells are necessary to detect the influence of the recharge operation on the ground water · Recommended water quality limits should be met at the point of injection · The reclaimed water should not contain measurable levels of pathogens at the point of injection Table continues on next page
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From page 34... ...
bSetbacks are recommended to protect potable water supply sources from contamination and to protect humans from unreasonable health risks due to exposure to reclaimed water. CSecondary treatment processes include activated sludge, trickling filters, rotating biological contactors, and many stabilization pond systems.
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From page 35... ...
.. virus ~nacr~var~on · Treatment reliability checks need to be provided Includes, but is not limited to, the following: · pH: daily · Turbidity: continuous · Coliform: daily · C12 residual: continuous · Drinking water standards: quarterly · Otherg: depends on constituent · Site-specific "Monitoring should include measurement of the concentrations of inorganic and organic compounds, or classes of compounds, that are known or suspected to be toxic, carcinogenic, teratogenic, or mutagenic and are not included in the drinking water standards.
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From page 36... ...
The proposed regulations, which have gone through several iterations, are designed to ensure that ground water extracted from an aquifer recharged by reclaimed water meets all drinking water standards and requires no treatment prior to distribution. Table 1-3 summarizes the proposed treatment process and site requirements.
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From page 37... ...
CNot applicable. dFrom edge of recharge operation to the nearest potable water supply well.
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From page 38... ...
California has not developed criteria for indirect potable reuse via surface water augmentation, although a framework has been proposed (California Potable Reuse Committee, 1996~. Augmentation of surface drinking water sources with reclaimed water in California requires two state permits a waste discharge or reclamation permit from a California Regional Water Quality Control Board and an amended water supply permit from the Department of Health Services.
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From page 39... ...
The first types of water reuse shown in Table 1-4, rapid-rate infiltration basin systems and absorption field systems, have less stringent water quality limits and treatment requirements than do the other types of reuse because the water receives some treatment as it percolates through the soil. Any wastewater land application system located over a potential source of drinking water must meet these standards.
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From page 40... ...
drinking water standards Injection to ground water No detectable fecal Secondary, filtration, coliforms/100 mla and disinfection 5.0 mg/liter TSS Primary and secondary U.S. drinking water standards Injection to formations of No detectable fecal Secondary, filtration, Floridian or Biscayne aquifers coliforms/100 mla disinfection, and having TDS <500 mg/liter 5.0 mg/liter TSS activated carbon 5 mg/liter TOC adsorption 0.2 mg/liter TOXd Primary and secondary U.S.
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From page 41... ...
Additionally, both the owner of the wastewater treatment plant that provides the reclaimed water for ground water recharge and the owner or operator of the ground water recharge project that uses the reclaimed water must obtain permits from the ADWR before any reclaimed water can be recharged (Arizona Department of Water Resources, 1995~. A single permit may be issued if the same applicant applies for both permits and the permits are sought for facilities located in a contiguous geographic area.
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From page 42... ...
While the maxim that drinking water should be obtained from the best available source should still be the guiding principle for water supply development, in some instances the best available source of additional water to augment natural sources of supply may be reclaimed water. No enforceable federal regulations currently govern the use of reclaimed water for potable purposes, and only a few states have developed detailed criteria for water reuse.
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From page 43... ...
1996. A proposed framework for regulating the indirect potable reuse of advance treated reclaimed water by surface water augmentation in California.
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From page 44... ...
1975. A "state-of-the-art" review of health aspects of Wastewater reclamation for ground water recharge.
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