Cyanide is well known as a toxin to humans and aquatic life. Consequently, limits on the discharge of cyanide have been imposed to protect the environment. Concentrations as low as 5 ppb have been reported to be detrimental to sensitive aquatic life; thus, the strictest limits for cyanide discharge are placed on waste water treatment plants. Measurements for cyanide in waste water are not very consistent at this concentration, so any type of interference or contamination will influence a facility's ability to demonstrate compliance with its discharge permit. This study formed part of a project conceived by a consortium of North Carolina waste water utilities that continued to violate discharge permits for a variety of species. The study was designed to determine sources of any interference or contamination that could lead to a bias in cyanide measurements using existing methodology. An earlier component of the larger study indicated that those plants using chlorination were most likely to have recurrent problems meeting their discharge permit levels for cyanide. In addition, the analytical method for total cyanide as practiced at the utility or contract laboratories was found to suffer many shortcomings. Published literature states that both nitrite and sulfide are known to interfere with the total cyanide analysis. This research, therefore, aimed to study the potential artifactual presence of cyanide utilizing an alternative methodology. The data collected from the various experiments were intended to validate if the cyanide formation was truly occurring in the chlorination process or if the cyanide were an artifact of the testing methodology. This was designed to be done through sampling before, during and after the chlorination process. These waste water samples were then treated to identify where the cyanide formation reaction was occurring and the chemical species involved. Determination of the levels of these chemical constituent was also performed to observe any correlation exists between these species and effluent cyanide concentrations. These collected waste water samples were treated in a variety of ways to account for possible chemical interfereces that may contribute to high cyanide concentrations. Approaches were then developed to control these reactions and to assure stabilization of collected samples during analysis. This study attempts to furnish an approach for waste water utilities to ensure accurate monitoring of total cyanide in their effluent, and there by identify the source of true cyanide contamination when permit violations occur.Master of Science in Environmental Engineerin
