Pilot-Scale Evaluation of Poultryponics: Insights into Nitrogen Utilization and Food Pathogen Dynamics

Poultry processing wastewater (PPW) is a nutrient-rich effluent with the potential for reuse in crop irrigation. This study investigated transforming PPW into a hydroponic nutrient solution using a pilot scale "poultryponics" system operated continuously for 222 days. The system treated ∼57 L d^-1 of real PPW and consisted of bioreactors (inoculated with a consortium of microalgae and nitrifying bacteria), clarifiers, membrane filters, a UV disinfection unit, and a deep-water hydroponic system. The system was evaluated in terms of nitrogen transformation, organic removal efficiency, and pathogen levels. Although soluble organic removal efficiencies (sCOD) were high (>80%) in all bioreactors, nitrification was limited due to high organic loading (350-800 mg sCOD L^-1), relatively short retention time (24 h), and low dissolved oxygen levels (<3.5 mg O₂ L^-1). Grow beds showed significant nitrification, indicating the importance of upstream organic removal. CO₂ supplementation (0.5% v/v) in bioreactors did not promote nitrification in the bioreactors but was beneficial for nitrification in grow beds due to pH-modulating effects. Microbiological analyses showed no Salmonella detection in bioreactors and substantial reductions in total coliform (∼40%) and aerobic plate counts (∼30%) after UV treatment. These findings demonstrate the sustainable and safe reuse of nutrient-rich industrial effluents in agriculture.