Effect of Hydrothermal Pre-treatment on Production of Volatile Fatty Acids from Thickened Waste Activated Sludge using Semi-continuous Fermentation

The research project focuses on the effect of hydro-thermal pre-treatment of the thickened waste activated sludge (TWAS). Reducing the amount of waste generated by the process called anaerobic digestion (AD) includes the benefits of low cost and supplies source of renewable energy. Fermentation is the first part of AD where volatile fatty acids (VFAs) are produced. In this study hydro-thermal pre-treatment was conducted before the fermentation process to enhance the production of VFAs from TWAS. The study is a comparison between the pre treated sludge and raw sludge using Semi-continuous fermentation for 40 days with hydraulic retention time of 3 days. TWAS was pre-treated at 170○C for 30 min at the pressure 3 bar before the semi-continuous fermentation process, and compared with the raw sample performance. It was found that the amount of VFAs produced from the pre-treated sludge were 26 % higher than that one from the raw sludge. Also, the chemical oxygen demand (COD) solubilisation for the hydrothermally pre-treated sample was higher than that of raw sludge.