Fast Disinfection of Contaminated Stormwater Using Peracetic Acid

Abstract

This work evaluates the performance of peracetic acid (PAA) for the disinfection of stormwater runoffs contaminated by domestic sewage with the objective of using the collecting systems as contact reactors for in-situ disinfection. PAA is increasingly being used as a substitute for chlorination in the disinfection of wastewaters because of its rapid degradability and the absence of chlorinated organic by-products. In Brazil, and despite the adoption of the separator system in sewage systems, there is a large amount of domestic effluents that are piped directly into the stormwater systems, contributing to the contamination of water bodies. The efficiency of the disinfection of Escherichia Coli was evaluated by applying different doses (2, 5 and 10 mg.L -1 ) of PAA with short contact times (2, 5 and 10 minutes) in real stormwater samples collected at three different points of the stormwater system of the city of Rio de Janeiro. Trials were performed simulating the conditions and flow times available in the stormwater sewers. The results were excellent, with removals up to 5 log units with 10 mg.L -1 peracetic acid and 2 minutes contact time. Where there was available a contact time of at least 5 minutes, a dose of 5 mg.L -1 was sufficient.