Treatment Alternatives for Controlling Chlorinated Organic Contaminants in Drinking Water

摘要

A pilot plant study was conducted by the City of Thornton, Colorado, to evaluate techniques for controlling chlorinated organic compounds formed in drinking water as a result of breakpoint, or free, chlorination. The pilot plant was operated for 46 months using the raw water sources available to the City's 20-mgd Columbine Water Treatment Plant. The treatment techniques evaluated included conventional coagulation and sedimentation, adsorption of organic precursors on powdered activated carbon (PAC), adsorption of chlorinated organic compounds on granular activated carbon (GAC), and alternative methods of disinfection, including the use of chloramines and chlorine dioxide in addition to the present practice of breakpoint chlorination. The effectiveness of the alternatives were assessed with respect to formation or removal of total trihalomethane (TTHM) and total organic halogen (TOX). In addition, the alternative disinfectants were evaluated for biocidal effectiveness. Based on the study findings, a process that employs chlorine dioxide in combination with chloramination was selected for full-scale evaluation.