Water Quality Improvement Using a TWF/C-PAM Treatment Agent and Reutilization Potential of Sewage Sludge as an Agricultural Soil Amendment

Abstract

The applicability of a torrefied wood flour/cationic polyacrylamide (TWF/C-PAM) treatment agent for pilot-scale wastewater treatment and the reutilization potential of the generated sewage sludge as an agricultural soil amendment were evaluated. The TWF/C-PAM treatment agent showed high removal efficiencies for turbidity 91.8%, suspended solids 96.4%, total phosphorus 90.0%, chemical oxygen demand 67.3%, and biochemical oxygen demand 61.2%. The treatment performance was comparable to that of conventional 10% polyaluminum chloride, although relatively low total nitrogen removal efficiency 10.3% was observed. Lettuce (Lactuca sativa L.) was cultivated in sewage sludge-amended soil presented with sludge addition ratios of 1%, 5%, 10%, and 30%. Chlorophyll and carotenoid contents increased up to the 5% treatment level, indicating the potential applicability of sewage sludge as an agricultural soil amendment. These findings demonstrate the potential of the TWF/C-PAM treatment process for simultaneous wastewater treatment and sewage sludge reutilization.