Controlling Disinfection By-Products Using Chlorine Profile and CT Tables at EL-Nobarya Drinking Water Treatment Plant, Egypt

Abstract

The present study aims to optimize the disinfection process at the El-Nobarya water treatment plant by developing a disinfection profile and utilizing CT tables as a secondary strategy, along with enhanced coagulation (EC), to achieve a constant reduction in Trihalomethanes (THM) levels and ensure adequate pathogen removal. Temperature effect was studied as chlorine profile was calculated based on highest and lowest water temperature recorded in the plant. Plant processes configuration (baffling factor) and efficiency (log removal) role in reducing chlorine dose by increasing contact time and reducing the log removal required was also determined. The results of disinfection profile revealed that more than 30 log inactivation of Giardia in summer and 11 log inactivation in winter was achieved by disinfection process. The log inactivation was reduced to 8 log in summer and 2.7 log in winter consequently. THM was reduced by more than 50%, even with high temperature and natural organic matter (NOM) level. Moreover, Giardia cysts were completely absent in the treated water. Chlorine dose was reduced from 8 to 5-5.5 gm/m³ with saving of 13000 EP /month. The results of the present study will help operators, consultants, and government agencies to reduce Disinfection Byproducts (DBPs) for existing, upgrading, and new water distribution systems in Egypt.