Industrial Effluents as a Source of Drinking Water Contamination

Contamination of drinking water supplies from industrial waste is a result of various types of industrial processes and disposal practices. Industries that use large amounts of water for processing have the potential to pollute waterways through the discharge of their waste into streams and rivers, or by run-off and seepage of stored wastes into nearby water sources. Other disposal practices  which cause water contamination include deep well injection and improper disposal of  wastes in surface impoundments.

Industrial waste consists of both organic and inorganic substances. Organic wastes include pesticide residues, solvents and cleaning fluids, dissolved residue from fruit and vegetables, and lignin from pulp and paper to name a few. Effluents can also contain inorganic wastes such as brine salts and metals. The Clean Water Act has standards for the permitted release of a limited amount of contaminants into waterways. This is an incentive for industry to pre-treat their water by neutralizing the chemically active components, recycling, dilution or extraction and collection for proper disposal.. More than 200,000 sources of waste water are regulated by the National Pollutant Discharge Elimination System (NPDES) permit program.

Industries which use large amounts of water in their processes include chemical manufacturers, steel plants, metal processers, textile manufacturers, and the following(1,4):

Agriculture. Run-off from crops contain pesticides, fertilizer, sediment. Run-off from animal production facilities contain bacteria, organic matter, nitrates, and phosphates.

Fruit and Vegetable Processing. Waste water contains high concentrations of dissolved organic matter and may be highly alkaline from the use of lye. Most of this water is now recycled.

Petroleum Refining. Oil is mixed with water in the refining process to remove salts and other impurities. It is then separated and collected. Most of this water is now recycled.

Pulp and Paper. The use of bisulfite and sulfurous acid or sulfur dioxide in the pulping process yields a waste sulfite liquor containing various wood by-products.  This can be reduced or recycled into various useful products.   There is presently a concern over the release of dioxins into waterways by the pulp and paper industry.

The waste disposal practices which presently pose a threat to drinking water supplies include deep well injection of wastes and wastes that are dumped and retained in surface impoundments or evaporation ponds.

Deep well injection is used mostly by the chemical industry. These wells range from 1000 to 9000 feet deep and are used for storage and disposal of wastes (3). Injection of highly toxic waste into aquifers or leakage of contaminants form confined areas cause water contamination.

Surface impoundments and evaporation ponds can cause groundwater contamination if they are not lined and seepage occurs. They are located near industrial sites and are used for settlement of suspended solids, removal of excess water by evaporation and biological treatment of waste. Leftover residues are shipped to landfills or applied to land as fill if it meets certain non-hazardous criteria. Some wastes are recycled such as silica(sand) and metals. The Resource Conservation and Recovery Act sets time limits for on site storage of disposed wastes. This is done to prevent ground water contamination and as an incentive to recycle or dispose of wastes in a timely manner.

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  References

1. U.S. EPA Planning Workshop to Develop Recommendations for a Ground Water Protection Strategy. 1980b. Appendixes. Washington DC. pp 171.

2. Final Report to the President and the Congress of the United States. 1973. National Water Commission, Water Policies for the Future. pp64-70.

3. U.S. EPA Handbook, Ground Water Vol. 1: Ground Water and Contamination. 1990. Office of Research and Development. Washington DC. EPA/625/6-90/016a.

4. National Summary of Water Quality Conditions, Inventory Report to Congress, 1994. URL: http://www.epa.gov/305b/execsum.html

This page was prepared by T.L. Pedersen , June 1997, UCD EXTOXNET FAQ Team.
Revised by B.T. Johnson, October 1997