Significance and behaviour of heavy metals in wastewater treatment processes. IV. Water quality standards and criteria.

Literature on the health aspects of the presence of heavy metals in water and wastewaters is reviewed and quality standards, criteria and legislation promulgated by the World Health Organisation, European Economic Community, U.S. Environmental Protection Agency and Government of the U.S.S.R. are assessed and compared. It is evident from the literature that standards applied differ according to the projected water use and that although standards for potable water are generally based on human health criteria, other factors including available technology and economics may be limiting. Emphasis has been placed on the protection of raw water quality as a result of the limited ability of potable water treatment processes to remove certain heavy metals. It is apparent that limitations on heavy metals in discharges from the chlor-alkali and cadmium salts and pigments industries are more stringent in the United States than in the European Economic Community. It is concluded that the finite availability of unpolluted freshwater will result in greater water re-use and that appropriate standards are required to protect potable supply, raw water and agricultural land from contamination by heavy metals.