Inclusion of Variable Disinfection Levels in Slug Feed Optimal Disinfection of Water Distribution Systems

Water distribution systems are vulnerable of being intentionally or accidentally contaminated. In the case of a contamination event the contaminated section of the water distribution system should be located, isolated and cleaned before it can be returned to regular service. Depending on the specific contaminant, the cleaning process mainly includes flushing and disinfection. All of the disinfection methods (for example: tablet, continuous and slug) require that the disinfectants will have minimal contact time (T) in a predefined concentration (C) with the pipes and the system's apparatuses. The regulatory agencies, such as the Ministry of Health in Israel or the American Water Work Association, publishes procedures for the disinfection of water systems in which usually only a single water main is considered and no specific procedures are given for larger portions of the water system. This paper presents an optimal operation plan for the disinfection of water distribution systems using the slug feed method while considering the injection times, flow rates and drainage locations while keeping variable disinfection C*T values in different areas of the network. The method is a two stage GA-EPANET procedure. It is demonstrated on a small real-world network section.