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Wastewater Disinfection with Peracetic Acid (PAA) and UV Combination: A Pilot Study at Muddy Creek Plant
Garg, A., V. Namboodiri, T. Bowman, B. Murugesan, AND A. Al-Anazi. Wastewater Disinfection with Peracetic Acid (PAA) and UV Combination: A Pilot Study at Muddy Creek Plant. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-19/084, 2019.
EPA and various US wastewater treatment plants are exploring alternative methods to reduce the high-energy cost to run the UV disinfection system. Combining UV with peracetic acid (PAA) is one of such possibilities. There are two major benefits of using UV for wastewater disinfection over chemical disinfectants. One, it does not form any disinfection byproducts (DBPs) and, two, it does not produce/leave any chemical residuals in the treated water. However, the higher cost is the biggest downside of the UV systems. UV lamps consume large amount of electric power that can put significant financial burden on the utility. Another disadvantage for UV disinfection is that it is not very effective in the waters with low UV transmittance or high solid content. Therefore a study report on the combination of PAA and UV treatment will be valuable for many utilities in US and around the world to improve waste water treatment efficiency with energy and cost savings.
For the past several years, Metropolitan Sewer District of Greater Cincinnati (MSD) and USEPA has been investigating the use of peracetic acid (PAA) as an alternative to chlorination and several aspects of its implementation in the real world. We have studied the treatment of secondary effluent with PAA alone and in combination with UV with an objective to increase the efficiency and reduce the cost of disinfection treatment. This report on PAA-UV disinfection summarizes the results from a full-scale plant-level pilot study that we conducted from January to July 2018 at MSD’s Muddy Creek Treatment Plant. In this study, we pre-treated secondary effluent with PAA and investigated its impact on UV disinfection efficiency and the rate of microbial inactivation. It was observed that pre-treating secondary effluent with low doses of PAA resulted in an increased UV efficiency, which, in turn, resulted in significant increase in the rate of microbial inactivation. The combined PAA-UV treatment achieved significantly greater log reduction in fecal coliform, and E. coli number. The membrane method was employed to measure the microbial inactivation. Results from this plant-level pilot study validates our lab and side-stream pilot studies that a PAA-UV sequential treatment is more effective than the individual UV or PAA treatments.