Risk assessment in water treatment processes for the development of a water safety plan – WSP

Abstract

Drinking Water Treatment Plants (DWTP) must ensure safe water supply; to this end, we applied risk assessment tools for the development of the Water Safety Plan (WSP) in a DWTP from Cali-Colombia, which supplies 1.4 million inhabitants. For the identification of hazards and risk assessment, four tools were used: exploratory analysis of turbidity data, inspection visits, hazard/hazardous event matrix and semiquantitative matrix. Under normal and extreme conditions of turbidity (>400-2500 UNT), it has been guaranteed the turbidity of treated water of 0.39 ± 0.15 UNT, showing the robustness of the DWTP. It was found that sixty percent of the 40 hazardous events had a very high risk level without considering control measures and it was possible reduce to 7% with existing control measures. The improvement or support programs should be directed towards the treatment phases identified as priority (chemical conditioning, coagulation, flocculation/clarification and filtration).