Modeling enhanced coagulation to improve ozone disinfection

Use of enhanced coagulation to improve disinfection capabilities (C x T) of a postsedimentation ozonation system was investigated at full scale at the Mannheim Water treatment Plant in Kitchener, Ont. Multiple linear regressi on was used to assess the effects of different water quality, environmental , and engineered parameters on the average ozone (O-3) concentration (C-avg ) in the O-3 contactor. It was found that C-avg was significantly affected by the transferred O-3 dose, the settled water pH, the settled water nonpur geable organic carbon concentration, the flow rate, and the water temperatu re. For the specific water tested, model predictions indicated that operati on of the plant under enhanced coagulation conditions could substantially i mprove the disinfection capacity of the ozone system, compared with convent ional coagulation. Modeling results also showed that the effect of flow rat e (i.e., contact time ) on C x T depended on the rate of O-3 decay. For rap id O-3 decay conditions, models predicted an increase in calculated C x T w ith increasing flow rate (i.e., decreased contact time).