Disinfection of poultry processing wastewater using advanced oxidation processes

Given the increasing demand of poultry products, poultry processing continues to generate a large volume of wastewater rich in diverse foodborne pathogens that require effective treatment to support safe reuse. This study evaluated the disinfection rate of photo-electrochemical (PEC) treatment, which combines electrochemical (EC) and photochemical (PC) treatments for poultry processing wastewater. Wastewater from the scald and inside-outside bird washer (IOBW) units were treated using independent 7 L and 30 L PEC reactors operated at 70 V and 100 V EC with a fixed 1.6% curcumin for PC. Treatment was conducted for 300 minutes with aliquots collected every 30 minutes for quantification of aerobic bacteria (AC), Enterobacteriaceae (EB), coliforms (CC), and E. coli, on Petrifilm™. Furthermore, samples at 0, 150 and 300 minutes were selectively enriched and plated on Campylobacter agar and xylose lysine tergitol-4 for Campylobacter and Salmonella detection, respectively. Microbial reductions were reported as log₁₀ CFU/mL and analyzed using linear mixed-effects model on R software (p ≤ 0.05) with a limit of detection of 1 CFU/mL. Across all wastewater types and reactor scales, PEC treatment at 70 V and 100 V achieved substantial reductions in AC, reducing initial loads of 5.4 - 6.2 log CFU/mL to 2.0 - 2.9 log CFU/mL within 300 minutes. Specifically, treatments at 100 V reduced AC to below the regulatory threshold of 500 CFU/mL (2.70 log CFU/mL) for wastewater reuse. EB, CC, and E. coli were completely inactivated, with faster disinfection generally observed at 100 V (120-180 minutes) compared to 70 V (180-210 minutes). Although differences between pathogen reductions were insignificant between 70 V and 100 V (p> 0.05), disinfection at 100 V showed a trend of quicker and greater microbial reduction across all microorganisms tested. Furthermore, Campylobacter and Salmonella were consistently eliminated within 150 minutes across all treatments. Overall, these findings demonstrate PEC as a viable, sustainable disinfection strategy which effectively reduced microorganisms including Campylobacter and Salmonella in processing wastewater, supporting safe reuse while reducing environmental impact.