Optimization of Thermal Pretreatment of Food Waste for Maximal Solubilization

Food waste has become an increasing concern across the globe. Anaerobic digestion (AD) has been recognized as an effective approach for handling this waste while generating biogas. AD's performance could be enhanced by improving the carbon conversion efficiency and leading to the lowest amount of residuals possible. For this purpose, various pretreatment approaches have been investigated. This study focuses on optimizing thermal pretreatment of food waste. In particular, three parameters, namely temperature, treatment time, and total solid content, were evaluated statistically for their effects on the increase of soluble chemical oxygen demand (SCOD). It was found that temperature and time had statistically significant impacts on the SCOD increase compared with the untreated controls. The optimal condition of 170°C, 60 min, and 118 g/L solid content led to a 1.92-fold increase of SCOD. After a 5-day fermentation, the pretreated slurries produced 17.1 g/L of volatile fatty acids. Results from this study could be used at large scale for pretreating food waste before AD for producing biogas or other valuable products.