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 Abstract

  Regulations on the Disposal of Arsenic Residuals From Drinking Water Treatment Plants (EPA/600/R-00/025) May 2000

Water treatment systems produce a product (clean water) and a residual of the treatment process. Restrictions have been placed on the discharge of residuals to water bodies and onto land. This report summarizes federal regulations and selected state regulations that govern the management of residuals produced by small drinking water treatment systems that remove arsenic from drinking water.

Arsenic is a naturally occurring contaminant in ground water, which is used by many small water treatment facilities as their primary source of water. This document reports on five water treatment processes known to be effective for arsenic removal:

  • Anion exchange
  • Activated alumina adsorption
  • Iron and manganese removal
  • Media adsorption
  • Membrane processes

For each technology, a brief description of the treatment process is provided, along with a discussion of the residual production characteristics. This report also discusses specific disposal methods and the method by which the residuals are managed:

  • Liquid residuals – direct discharges, indirect discharges, underground injection, and land disposal
  • Solid and sludge residuals – solid waste landfill, hazardous water landfill, lagoons, reuse of hazardous waste, reuse of solid waste, and off-site disposal

Under the Safe Drinking Water Act (SDWA), a maximum contaminant level (MCL) of 0.05 milligrams per liter (mg/L) was established for arsenic in drinking water. Under the 1996 SDWA Amendments, EPA was required to develop a revised arsenic regulation by January 2001. Concerns have been raised about the technical feasibility and regulatory implication of a more stringent arsenic MCL on the disposal of residuals from the arsenic removal processes.

This report provides an overview of the federal regulations that apply to the management of residuals, with a focus on arsenic-removal residuals. The overview offers guidance on the federal regulatory requirements of residuals management so that water suppliers can evaluate compliance of existing practices and plan for needed changes in treatment plant operations.

Federal regulations summarized in this report include the:

  • Clean Water Act (National Pollutant Discharge Elimination System and pretreatment)
  • Safe Drinking Water Act (underground injection control and lagoons)
  • Resource Conservation and Recovery Act (Subtitles C and D)

In addition to these federal regulations, state regulations were also reviewed. Seven states (Arizona, California, Maine, Nebraska, New Mexico, Nevada, and Pennsylvania) were chosen for this report because of their arsenic occurrence and regional representation. The review of the state regulations also focused on different management options available for liquid and solid residuals generated by arsenic removal. Many components of the state regulatory programs were consistent with the federal minimum requirements. However, the state programs differed from federal program requirements and each other regarding the:

  • Surface water quality standards applicable to control the amount of arsenic in direct discharges of liquid effluent
  • Local limits that specify how much arsenic may be discharged to a sanitary sewer system
  • Regulation of solid waste landfills
  • Protection of ground water resources
  • Regulation of land application activities

Contact

Thomas J. Sorg


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