Interaction of physicochemical parameters during pressurized in-vessel composting of food waste

Abstract The current paper investigates potential interactions and correlations between physicochemical parameters during pressurized in-vessel composting of food waste. A laboratory-scale bioreactor, which operates semi-continuously under 0.6 bar air pressure, was designed for the purpose of this study. The studied evaluations included operational indices as well as compost maturity indices. The evolution of different physicochemical parameters showed that food waste could be composted successfully in 12 days. During the active phase of composting, high CO2 generation involved high temperature and high internal air pressure, revealing vigorous microbial activity. Moreover, the final compost was satisfactory for its agricultural application in terms of C/N ratio, EC, and NH4+-N content. The correlation matrix and the Principal Component Analysis showed that nitrate negatively correlates with ΔP, CO2, C/N ratio, EC and ammonium. Whereas, ΔP positively correlates with CO2, EC and NH4. Positive correlations were also observed between CO2 and EC, NH4; and C/N ratio and EC.