A CASE STUDY OF CHARLESTON CPW: SOME PRACTICAL CONSIDERATIONS IN USING CHLORAMINATION

摘要

The Commissioners of Public Works of the City of Charleston, SC (CPW) is a regional utility providing potable water service to approximately 400,000 residents of the Greater Charleston Metropolitan Area. As a result of the Trihalomethane Regulation of 1979, CPW conducted extensive bench and pilot scale testing which determined that conversion to chloramine disinfection would allow the new THM standard of 100 ppb to be met. In February 1985, CPW converted from the use of free chlorine to the use of chloramination as the primary and secondary disinfectants. In 1992, in conformance with the Surface Water Treatment Rule, CPW returned to the use of free chlorine as the primary disinfectant while continuing with chloramination for secondary disinfection.While the primary impetus for conversion to chloramination was initially the control of THMs, many other benefits have been realized and these are discussed. In addition, there is important operational, maintenance, and public education aspects associated with using chloramines and it is the objective of this paper to examine some of these considerations.