Centrifugal dewatering of blended sludge from drinking water treatment plant and wastewater treatment plant

The blended sludge taken from drinking water treatment plant (WTP) and wastewater treatment plant (WWTP) for centrifugal dewatering was proposed. Residual products of polyaluminum chloride and inorganic particles in alum sludge from WTP were considered to improve dewaterability of sewage sludge from WWTP through the charge neutralization, adsorption bridging, squeezing, and skeleton builders. The sludge with blend ratio of 1:1 and no PAM addition, the specific resistance to filtration was 1.27 × 10¹³ m/kg, the moisture content was 62% after centrifugal dewatering, and more excellent dewatering performance of blended sludge was proved. Scanning electron microscope showed that the surface of blended sludge had more rough and porosity structure than the sewage sludge. EDS analysis showed that residual alum and inorganic particles existed in blended sludge. 3D-Excitation-emission matrix was used to analyze change of protein-like of sewage sludge and blended sludge with dewatering process. The results implied that alum sludge acted as chemical conditioner and physical conditioner in blended sludge. A hypothesis was suggested to describe the centrifugal dewatering process of blended sludge. The final disposal options of the blended sludge would be landfilling and building material utilization.