Swine effluent post-treatment by alkaline control and UV radiation combined for water reuse

Water reuse is widely practiced by industries, including swine farms, to reduce the consumption of clean water. However, water reuse requires controlling physical and chemical parameters of quality and mainly pathogens to meet the regulation limits recommended for no potable reuse. This paper presents an exploratory evaluation of the combined disinfection use of alkaline control and ultraviolet radiation to suit the sanitary parameter of secondary effluent from a swine manure treatment plant for agricultural water reuse. The efficiency of disinfection was measured by total coliforms, Escherichia coil and Salmonella at three pH levels (7.5, 9 and 10), two settling times (30 and 60 min), and two contact times for ultraviolet radiation (0 and 60 s) at 160.5 +/- 20.8 mJ/cm(2). The highest inactivation responses were 3.7 log for total coliforms, 3.8 log for Escherichia coli and 4.0 log for Salmonella at pH 10, 60 min of settling and 60 s of exposure to UV radiation. These results show an increase in the disinfection efficiency of 2.8 log for total coliforms and Escherichia coli and 2.4 log for Salmonella in comparison to pH control alone. Therefore, a previous alkaline treatment forces the sedimentation of the total suspended solids, responsible for reducing the ultraviolet light germicidal effect, and, for this reason, in the next stage of disinfection the efficiency was higher. The application of both disinfection agents sequentially yielded better results to improve biosecurity status for water reuse. (C) 2016 Elsevier Ltd. All rights reserved.