Effect of Hydrothermal Pretreatment on the Acidification of Thickened Waste Activated Sludge and Source Separated Organics

Abstract

The objective of this study was to investigate the impact of the hydrothermal pre-treatment (HTP) on solubilization and acidification of thickened waste activated sludge (TWAS) and source separated organics (SSO). The temperatures, retention times, and pressures used in this study ranges were 150-240°C, 5-30 min, and 69-488 psi, respectively. Mesophilic batch acidification tests were conducted for all pretreated and non-pretreated samples. For the TWAS, the highest overall COD solubilization due to HTP and acidification of 64% was observed at “200°C-10 min” compared to 30% for raw TWAS. The highest VFAs yield of 2856 mg VFAs/g VSS added was observed at “190°C-10 min” compared to 1251 for raw TWAS. For the SSO, the highest overall COD solubilization of 63% was observed at “210°C-20 min” compared to 17% for raw SSO. The highest VFAs yield of 1536 mg VFAs/g VSS added was observed at “210°C-20 min” compared to 768 for raw SSO.