Research note: Reduction of Salmonella enterica in simulated wastewater using electrochemical and photochemical processes

Salmonella is a poultry-borne pathogen causing numerous human outbreaks in the U.S. Consequently, Salmonella, along with other pathogens, can be found in wastewater generated from poultry processing. It is essential to treat this wastewater before discharge, recycle, or reuse. Hence, this study investigated the utility of Advanced Oxidation Processes (AOPs) like electrochemical (EC) and photochemical processes (PC) to disinfect Salmonella in simulated wastewater (contaminated water). Three Salmonella serotypes: Kentucky (SK), Infantis (SI), and Typhimurium (ST) were chosen based on their ability to persist in poultry processing environments and cause infection. These serotypes, prepared in water at 6 to 7 Log₁₀ CFU/mL were exposed to alternating current in EC with a voltage demand of 30 V, 40 V, and 50 V where ammonium sulfate was added as an electrolyte and ferrous sulfate to facilitate AOP production; and PC with curcumin, a photosensitizer at 0.40 % (1X) and 0.80 % (2X) to produce singlet oxygen and hydrogen peroxide that are lethal to pathogens. During the disinfection process, samples were collected every 20 min for 180 min and plated on XLD agar to assess Salmonella reduction. The data were analyzed using ANOVA in SAS. Bacterial reduction differed (P < 0.0001) between serotypes at 30 V and SK had the greatest reduction (3.13 Log₁₀ CFU/mL), whereas there was no difference in reduction between the serotypes at 40 V (P = 0.98) where all the serotypes had more reduction than at 30 V. Complete attenuation of the serotypes was seen at 50 V (P < 0.0001), where SI reduced the most (5.96 Log₁₀ CFU/mL) followed by ST (5.15 Log₁₀ CFU/mL) after 140 min. SK was also attenuated (3.34 Log₁₀ CFU/mL) after 60 min due to a lower starting concentration. This preliminary result suggests that Salmonella in poultry processing wastewater can be effectively attenuated through AOPs, offering a potential solution for enhancing poultry wastewater treatment.