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ABSTRACT: Results are presented that explore the possibility of organocyanide compounds in wastewater contributing to elevated cyanide levels in the chlorinated effluents of publicly owned treatment works. Four model compounds, acetonitrile, amygdalin, cyanocobalamin, and 2-acetoxy-3-butenenitrile, were selected and tested with varying chlorine dosages for release of cyanide by total and diffusible cyanide procedures. The coenzyme form of vitamin B^sub 12^, which does not contain cyanide, was also tested. It was found that acetonitrile and amygdalin do not yield cyanide with or without chlorination, cyanocobalamin had increased release with increased chlorine dosages, and 2-acetoxy-3butenenitrile had generally decreased release of cyanide with increased chlorine dosages. Both cyanocobalamin and coenzyme vitamin B^sub 12^ gave evidence of the formation of the cobalt-cyanide complex after chlorination, even though the molecular structure of the coenzyme vitamin B^sub 12^ contains no cyanide. Water Environ. Res., 74, 51 (2002).
KEYWORDS: organocyanides, chlorination, water quality standards, analytical methods.
Introduction
In numerous publicly owned treatment works (POTWs) across the United States, chlorinated effluents are often found to contain cyanide at levels exceeding influent concentrations (Environ Inc., 1996, and Sawyer et al., 1996). Cyanide discharge limits are based on U.S. Environmental Protection Agency (U.S. EPA) water quality criteria that can be as low as 1.0 (mu)g/L for marine environments (ATSDR, 1997). Because water quality criteria and related discharge limits are typically low, small increases in detectable cyanide can result in permitted levels being exceeded.
The causes of elevated cyanide levels in chlorinated effluents are not clear. One possibility is interference in sample preservation and analytical methods. It has been reported that the colorimetric procedure for cyanide is sensitive to the presence...