Chlorine has been applied as the main disinfectant in US drinking water treatment for a century. Chlorination is low cost and effective, yet there are problems with this technology, including disagreeable taste of treated drinking water and formation of toxic and potentially carcinogenic disinfection byproducts (DBPs). Alternative disinfection methods including ozone, ferrate and UV light have been studied. They are not widely applied in drinking water treatment because of problems such as the costly generation process or no residual in the system.
Peracetic acid, an easy-to-use and economic friendly oxidant, has been applied as an alternative disinfectant to chlorine in wastewater treatment. However, the study and application of PAA in drinking water treatment is limited. In this research, PAA disinfection and its use to control DBP formation during subsequent chlorination was examined. Different PAA operation scenarios were tested: disinfection in the dark at 20 C with contact times up to 72 hours, decay under direct sunlight up to 18 hours and decay in the dark at 20 C with different short contact times. Best DBP control effect was observed in the 72-hour PAA pre-oxidation test. Direct sunlight accelerated PAA decomposition and shown higher ability to drop the amount of DBPs formed during subsequent chlorination. Among the scenarios tested in this study, the optimum disinfection condition for PAA was 2 hours of PAA pre-disinfection in the dark at 20 C.