AWWA ACE95055

The use of free chlorine as a drinking water disinfectant results in the formation of trihalomethanes (THMs), which are subject to regulation by the US Environmental Protection Agency (USEPA). An attractive alternative to chlorination is the use of ozone as a primary disinfectant with chloramines as a secondary or residual disinfectant; THMs are not formed at significant levels. Cyanogen chloride (CNCl), however, is one disinfectant by-product (DBP) which as been found to be preferentially formed in chloraminated drinking waters. Additionally, it appears that the use of ozone prior to chloramination may enhance CNCl formation in some waters. Although currently unregulated by the USEPA, CNCl has appeared on the Drinking Water Priority List (DWPL) since 1988; it is a candidate for regulation. The USEPA recently proposed that CNCl be monitored quarterly by drinking water utilities which use chloramines as a disinfectant and serve a population of at least 100,000. The objectives of the proposal were to understand the water quality parameters affecting the formation of CNCl, and to establish a database on the occurrence of the compound. This paper presents and discusses a reaction pathway which may be responsible, at least in part, for the presence of CNCl in chloraminated waters. CNCl has been observed to form from the reaction of monochloramine with formaldehyde. Humic acid and glycine, potential formaldehyde precursors, were found to react with chloramines to produce CNCl. An additional research focus has been the development of an accurate, sensitive method of analysis for CNCl; this effort resulted in an equilibration chamber method.

Product Details

Published:

01/01/1995

ISBN(s):

0898678331

Number of Pages:

11

File Size:

1 file , 320 KB