Use of Reclaimed Water and Sludge in Food Crop Production (1996) / Chapter Skim
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7 Regulations Governing Agricultural Use of Municipal Wastewater and Sludge
7 Regulations Governing Agricultural Use of Municipal Wastewater and Sludge
Pages 120-150
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From page 120... ...
that have active water reuse programs have developed comprehensive, numerical water quality criteria for different water uses, including crop irrigation. Pathogen reduction continues to be the major concern, and microbiological limits for treated effluents are based largely on practical experience within the public health community, and on the expected performance of Wastewater treatment processes.
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From page 121... ...
Florida normally restricts the agricultural use of reclaimed water to those for crops that are skinned, cooked, or thermally processed before consumption (EPA, 1992~. Chemical pollutants in treated municipal wastewater have not been targeted by state regulations for reclaimed water.
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From page 122... ...
FEDERAL STANDARDS FOR THE CONTROL OF PATHOGENS IN SEWAGE SLUDGE Standards and management practices for the reduction of pathogens to acceptable levels prior to human or animal contact and vector attraction reduction are major aspects of the Part 503 Sludge Rule. Based upon pathogen reduction criteria, the Rule divides sludge into two categories, Class A (safe for direct contact)
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From page 123... ...
Or If levels of enteric virus and/or helm~nth ova prior to pathogen treatment are 21 PFU or if viable ova are present, then test after treatment. Document process operating parameters to achieve < 1 PFU/4 crams total solids for virus and < 1 viable ova/4 grams total solids for helminth ova.
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From page 124... ...
Helminth ova are among the most environmentally resistant of the infectious agents, and the time required for their reduction would be more than sufficient for the reduction of bacterial and viral pathogens. The Part 503 Sludge Rule requires a 20-month time period to elapse prior to harvesting root crops and a 14-month time period before harvest of other crops that touch the ground.
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From page 125... ...
APPROACHES TO TOXIC CHEMICAL REGULATION IN SLUDGE AND WASTEWATER LAND APPLICATION Philosophically, pollutant inputs to soils through land application of wastewater and sewage sludge may be regulated through two approaches (Chang et al.
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From page 126... ...
Consequently, the pollutant loading from all sources including land application of wastewater and sewage sludge must also be very low in order to maintain the balance and prevent any net accumulation. Regulations and guidelines that employ this principle must set very stringent toxic chemical pollutant loading limits for soils that can only be met by preventing all toxic chemical pollutants from entering wastewater collection and treatment systems, or by requiring the use of advanced levels of treatment to physically strip pollutants out of the effluent or sludge prior to land application.
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From page 127... ...
EPA's approach is premised on the condition that chemical pollutants will accumulate in the soil with each application of sludge. The risk assessment considers pollutant transport through various environmental exposure pathways, and has the objective of setting maximum pollutant loading limits and minimum sludge quality requirements for cropland application of sewage sludge.
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From page 128... ...
Hazard Identification The first step in the risk assessment process" hazard identification is to determine the nature of the effects that may be experienced by a human exposed to an identified pollutant and whether evidence of toxicity exists sufficient to warrant a quantitative risk assessment. Data are gathered on a specific pollutant and qualitatively evaluated based on the type of health effect produced, the conditions of exposure, and the metabolic processes that govern pollutant behavior within the human body or other organism studied.
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From page 129... ...
· The concentration of the pollutant in sewage sludge is already low enough that the estimated annual loading to cropland soil would result in an annual pollutant loading rate within allowable nsk-based levels. Based on these criteria, EPA exempted all of the organic pollutants under consideration.
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From page 130... ...
. For the purposes of the Part 503 Sludge Rule, models were developed to determine the maximum amount of pollutant that could be added to the soil (otherwise known as a Pollutant loading")
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From page 131... ...
Pyrene x Chlordane x x x DDT/DDE/DDD x x x (total) Heptachlor x x x Hexachlorobenzene x Hexachlorobutadiene x x Lindane x x x N-Nitroso dimethylamine x x PCBs x Toxaphene x x x Trichloroethylene x x pollutant loading rate," sets the total allowable level of sludge-borne pollutant that can be added to the soil and still maintain an acceptable level of exposure to the HE!
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From page 132... ...
To provide flexibility in applying sludges and to expedite the use of sewage sludge in nonagricultural land application, several variations in pollutant loading limits were derived from the risk-based cumulative pollutant loading rates. These alternative limits are described below and include pollutant concentration limits, ceiling concentration limits for pollutants, and annual pollutant loading rates.
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From page 133... ...
The nsk-based, cumulative pollutant loading rate (kg of pollutant/ha for the life span of the application site) is then uniformly distributed among 1,000 metric tons of sludge/ha, and a maximum permissible pollutant concentration (in kg of pollutant/ton of sludge or in mg of pollutant/kg of sludge)
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From page 134... ...
EVALUATION OF FEDERAL STANDARDS FOR CHEMICAL POLLUTANTS IN SEWAGE SLUDGE The objectives of the Part 503 Sludge Rule are to protect human health and the environment from reasonably anticipated adverse effect of pollutants in sewage sludge and to encourage the beneficial use of sewage sludge. If the regulation is viewed in this manner, the risk assessment approach used by EPA to establish the numerical limits (cumulative pollutant loading rate)
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From page 135... ...
Following a review of public comments on the proposed rule, the Agency undertook a screening exercise to reevaluate the need to regulate these 12 organic pollutants. The exercise resulted in no organic chemicals being regulated under the final rule promulgated in 1993.
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From page 136... ...
However, there are four pollutants (PCBs, benzo~a~pyrene, hexachIorobenzene and NNitrosodimethylamine3 whose 99th percentile concentrations resulted in calculated APERs higher than those calculated by the exposure assessment. When calculating the APER, EPA used 7 metric tons as the annual whole sludge application rate for agricultural land.
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From page 137... ...
137 Cal U
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From page 138... ...
In the Part 503 Sludge Rule, the final numerical limit of a pollutant is the lowest cumulative pollutant loading of all 14 exposure pathways. Because other, nonfood-chain pathways resulted in lower pollutant limits, the final cumulative pollutant loacling for 10 chemical pollutants currently being regulated are all significantly lower than any of the limits that would be derived from the human food-chain exposure pathways.
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From page 139... ...
the Maximum Pollutant Loading Rate Calculated from Food-Cha~n Exposure Pathways Cumulative Maximum Permissible Pollutant Loading Rate Pollutant Loading (kg/ha) PollutantRate ~g/ha)
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From page 140... ...
Over the years, federal agencies have not exercised direct regulatory authority over either wastewater irrigation or other type of effluent reuse, except through provisions in the National Pollutant Discharge Elimination System permit system which regulates the discharge of treated wastewater effluents. In practice, wastewater irrigation is normally treated as a community-wide environmental sanitation and public work improvement project that should undergo rigorous facility planning and engineering evaluation (EPA, libel)
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From page 141... ...
13. Reclaimed water applied to most food crops, particularly those that can be eaten uncooked, should be processed at least through secondary treatment followed by filtration and adequate disinfection.
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From page 142... ...
The regulation permitted the use of untreated wastewater for irrigating crops that would be cooked before consumption, provided that a 30-day or longer waiting period was observed prior to harvest. It also permitted the use of reclaimed water for fruit and nut trees and melon crops if the products did not come into direct contact with the wastewater.
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From page 143... ...
, and on-line chlorine residual and turbidity; · treatment reliability provisions; · site management practices that prevent workers and residents from being exposed to applied water and contaminated soils at the application site (providing setback distance, limiting public and worker access, posting warning signs, cross-connection prevention, hydraulic loading rate, etch; and · water management practices that minimize contamination of crops (specifying method of irrigation and/or types of crops permitted, requiring waiting period for crop harvesting or animal grazing, maximum water application rate, etc.) Regulations define the conditions necessary to minimize human exposure to pathogens.
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From page 144... ...
require an extended waiting period before animals are allowed on fields irrigated with lower-quality wastewater effluents. So far, trace chemical contaminants in treated municipal wastewater have not been targeted by State regulations or EPA guidelines for reclaimed water because their concentrations in wastewater receiving a minimum of secondary treatment are comparable to conventional sources of irrigation water (see Chapter 4~.
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From page 145... ...
While the public health safety record for reclaimed water irrigation has been excellent, there are little epidemiological data to support or refute the currently regulated levels (Crook, 1978; 1982~. For developing countries, recent research in epidemiology indicates that the public health risks resulting from crop irrigation with treated municipal wastewater are overestimated, and that the United States guideline may be "unjustifiably restrictive, particularly with respect of bacterial pathogens" (WorId Health Organization, 19891.
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From page 146... ...
146 The Use of Reclaimed Water and Sludge in Food Crop Production TABLE 7.14 Concentration of Trace Elements and Toxic Organic Chemicals in Selected Treated Effluents in California San lose WhiHier Pollutant Unit Creek Narrow Arsenic Aluminum Barium Cadmium Chromium Lead Pomona NPDWSa mg/1 mg/! mg/1 mg/1 mg/1 mg/1 Manganese mg/1 Mercury Selenium Silver Lindane Endnn Toxaphene Methoxychlor 2,4-D 2,4,5-D Turbidity Total Coliform mg/1 mg/1 mg/!
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From page 147... ...
In terms of trace elements, sewage sludge that is applied according to the pollutant loading rates specified in Part 503 should not affect the safety of the nation's food supply. The pollutant loading rates are set by the maximum permissible loading rates of nonfood-chain
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From page 148... ...
Regulations for Effluent Irrigation State regulations governing reclaimed wastewater for crop irrigation rely on wastewater treatment and site management to (~) minimize the presence of pathogens, (2)
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From page 149... ...
1981. Process design manual for land application of municipal wastewater.
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From page 150... ...
1985. Irrigation water quality criteria in Irrigation with ~, G
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