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About UNEP
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United Nations Environment Programme
Division of Technology, Industry and Economics
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Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>

United States

BOD/TSS

Secondary treatment is required as a minimum treatment, defined as effluent quality of 45 mg/L BOD5 and 60 mg/L SS. Either BOD5 or CBOD5 may be the permit criteria. Receiving water quality for rivers and streams is based on a 7 day consecutive 10 year low flow regime (7Q10). Mass limits for discharges are usually set using the 7Q10, and average annual plant design flow. Discharge limits of 10 mg/L BOD5 and 10 mg/L SS may be set in very sensitive environmental discharge conditions.

To locate remaining sources of water pollution in water bodies, where quality is low despite in place pollution controls, the EPA is moving towards total watershed management by permitting total daily maximum loads (TDMLs) in order to better control overall pollutant loadings to a watershed. Individual states identify and develop TMDLS for waters that fail to meet water quality standards despite pollution controls. Sources can trade TDML allowances.

The EPA National policy on Combined Sewer Overflow (CSO) Control was issued in 1994 and identifies 9 minimum controls to meet the technology-based requirements of the Clean Water Act. The CSO National Policy requires municipalities to develop long-term control plans and lays out targets for CSO controls to meet water quality standards and Clean Water Act requirements.

Nine minimum controls are:

  1. Proper operation and regular maintenance programs for the collection system and CSOs.
  2. Maximum use of the collection system for storage.
  3. Review and modification of pretreatment requirements to ensure that CSO impacts are minimized.
  4. Maximization of flow to the publicly owned treatment works for treatment.
  5. Elimination of CSOs during dry weather.
  6. Control of solid and floatable materials in CSOs.
  7. Pollution prevention programs to reduce contaminants in CSOs.
  8. Public notification to ensure that the public receives adequate notification of CSO occurrences and impacts.
  9. Monitoring to effectively characterize COS impacts and the efficacy of CSO controls.

The Comprehensive Environmental Response, Compensation and Liability Act (also known as the Superfund Act) covers wastewater exfiltration and overflow in the collection system, storage leaks, effluent and solids disposal, if they pose a threat to public health, welfare or environment.

Disinfection

Individual states develop site-specific water quality standards which mandate disinfection levels for municipal treatment plants. Guidance is provided by US EPA and other federal agencies, based upon 50 percent of the fecal coliform density at which a public health risk has been shown. Presently, if there is no primary contact with the receiving water, no disinfection or 800 MPN/100 mL fecal coliform is acceptable. Primary recreational contact with the water requires 200 MPN/100 mL. Reuse, irrigation and discharge to shellfish waters requires disinfection to 2.2 fecal coliforms/100 mL.

The most usual statistical basis is a minimum of 5 samples in 30 days. California has instituted a 7 day median value criteria.

Eighteen (18 ) states have seasonal disinfection requirements only.

Biosolids

The federal government is directly involved in the control of biosolids management practices, through municipal solid waste landfill regulations (40 CFR Part 258), technical standards for the use and disposal of biosolids (40 CFR Part 503), and expanded NPDES programs requiring federal permitting for biosolids use and disposal (40 CFR Part 122-124 and 501).

The Part 503 technical standards affect generators, processors, users and disposers of biosolids and domestic septage, and address land application, surface disposal and incineration.

Land application is defined as biosolids applied to land at agronomic rates for beneficial use. Biosolids for land application must meet Part 503's heavy metal pollutant ceiling concentration limits, Class B requirements for pathogen reduction, and vector attraction reduction requirements. General requirements and management practices apply unless the biosolids meet high quality pollutant concentration limits, Class A pathogen reduction requirements and vector attraction reduction processing requirements.

Surface disposal requirements apply to lined and unlined monofills, dedicated disposal surface application sites and piles, mounds or lagoons used for final disposal, defined as longer than 2 years. Metals concentration limits apply for unlined sites. There are management practice requirements for site location, control of runoff, methane gas monitoring, crop production, grazing and public access. States can establish site specific more stringent requirements.

Incineration requirements limit concentrations of heavy metals in biosolids fed to incinerators, and the concentration of total hydrocarbons or carbon monoxide in the exit gas from incinerator stacks. Management practices and frequency of monitoring, record keeping and reporting requirements are also established. Continuous emissions monitoring equipment, performance tests, and site-specific air modelling are required.

Facilities in states which do not have a delegated federal program must comply with both state and federal biosolids management programs.

Other

General Pretreatment Regulations in the U.S. require all publicly owned treatment works with flows greater than 19 ML/d, and smaller plants with significant industrial discharges to the collection system, to establish a local pretreatment program. Explosive, obstructive, excessively variable and excessively hot pollutants cannot be discharged to collection systems. One hundred and twenty-six (126) priority pollutants are also regulated by the General Pretreatment Regulation, and are locally enforced and implemented through the NPDES permit program. Three hundred and sixty-six (366) extremely hazardous substances have been identified, and must be traced from point of generation to disposal if municipal landfills are used for solids disposal, or if the substance does not mix with the domestic wastewater before it enters the treatment works. State and local officials must be notified of the presence of extremely hazardous substances used as part of the wastewater treatment, i.e.: chlorine and sulfur dioxide, if in excess of specified threshold amounts.
Under the Clean Air Act, emissions of carbon monoxide, particulate, lead, nitrous oxide, ozone and sulfur oxide emissions from incinerators, dryers, engines and boilers are regulated. If pollutants defined as hazardous are emitted at greater than a threshold mass, an air discharge permit is also required.

Roles of engineering firms, contractors and public agencies

Engineering firms in North America have been instrumental in developing regulations; providing regulators with the technical background for setting effluent limits and management guidelines. This work has been undertaken both on contract and on a volunteer basis, depending upon the situation.

Public agencies such as the Natural Sciences and Engineering Research Council in Canada and the US Environmental Protection Agency (EPA), and not-for-profit organizations such as the US based Water Environment Federation Research Foundation, fund and manage research to extend the detection limits of laboratory tests, determine toxicity of given substances, and to establish treatment performance standards.

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