Disinfection of Campylobacter Species and Salmonella Typhimurium in Contaminated Water Using Advanced Oxidation Processes

Abstract

Poultry processing generates pathogen-rich wastewater. Conventional disinfection methods like aerobic digestion and chlorination, although effective, impose considerable operational cost and generate disinfectant by-products. Integrated recycling systems present a promising opportunity for enhancing resources and sustainability. This study investigated the use of Advanced Oxidation Processes (AOPs), specifically electrochemical (EC) and photochemical (PC) treatments, to disinfect Campylobacter species (jejuni (Cj) and coli (Cc)) and Salmonella Typhimurium (ST) in contaminated water to simulate bacterial conditions in wastewater. The inoculum was prepared to produce 7 L of 6 log₁₀ CFU/mL contaminated water. The water was subjected to alternating current in EC treatments with a voltage demand of 50 V and 70 V and ferrous sulfate as a Fenton-related catalyst, alongside PC treatments using curcumin, a photosensitizer at concentrations of 0.8% and 1.6% to generate singlet oxygen and hydrogen peroxide. Samples were collected every 30 min for 300 min and plated on Campylobacter agar that was incubated at 42 °C for 48 h. Furthermore, Cj was combined with ST to make a mixed inoculum typical of poultry wastewater and exposed to the same photo-electrochemical (PEC) treatments. Bacterial growth was assessed on Campylobacter and XLD agar. Cj was completely disinfected after 150 min (4.70 log CFU/mL) at 50 V and 120 min (5.97 log CFU/mL) at 70 V of treatment whereas Cc was disinfected after 210 min (5.68 log CFU/mL) at 50 V and 180 min (5.99 log CFU/mL) at 70 V. While the rate of disinfection varied between Campylobacter species and in response to the voltage of the EC treatment, the concentration of curcumin in PC treatment had no impact on bacterial disinfection rates. In a mixed population, Cj and ST exhibited a complete reduction in 120 min (6.07 log CFU/mL), establishing an optimal condition of both EC (70 V) and PC (1.6%) for effective removal of both pathogens. Our findings suggest that combined PEC treatments effectively killed Campylobacter and Salmonella in contaminated water, highlighting the potential of AOPs as a sustainable poultry wastewater disinfection strategy.