Using modified biochar as a physical-chemical conditioner for waste activated sludge dewatering

The development of safe, efficient, environmentally friendly and cheap skeleton particles is a hot spot in the study of sludge reduction and resource utilization in the field of environmental engineering in my country. In this study, we prepared for the first time a biochar P-BC modified with polyaluminum chloride as a physical and chemical conditioning agent to be used in the field of sludge dewatering. The sludge moisture content, sludge specific resistance, and sludge compressibility coefficient are used to evaluate the sludge dewatering effect of P-BC. When the dosage of P-BC is 1.25 g/gTSS, WC drops to 79.65±3%, and SRF drops to 7.73±0.1×1012 m/kg, indicating that the sludge dewatering performance has been significantly improved. Through analysis of changes in Zeta potential, sludge particle size and distribution of extracellular polymer components before and after sludge pretreatment, the mechanism of P-BC promotion of sludge dewatering was explored, and it was proved that P-BC can neutralize sludge. The negative charge in the sludge promotes the agglomeration of sludge particles, promotes the conversion of the bound water inside the EPS to free water, and effectively improves the sludge dewatering effect.