The Waste Recycling Approach for Enhancing Wastewater Sludge Dewaterability by Using Iron-Mud (Im) / Sawdust Derived Carbon Composite

Abstract

The dewaterability of wastewater sludge by solid waste of iron-mud (IM) /carbon (IMS) composite prepared via in-situ carbothermal reduction method is systematically studied in this paper. The effects of different IMS materials, IM dosages and stirring speeds on sludge dewaterability are investigated, including water content, capillary suction time, EPS contents and particle size. The results of dewatering tests demonstrated that IMS materials enhanced sludge dewaterability, which resulted in 39.85% capillary suction time reduction and 13.26 % water content reduction in dewatered sludge under optimum parameters (IMS-3 dosage 8% DS; stirring speed 250 r/min for 30 minutes). The EPR and scavenging experiments were conducted to better understand mechanism of the dewatering process. From the results, it can be reasonably concluded that both .OH and •O2- worked collaboratively during dewatering process. Furthermore, additional analysis was implemented for the particle size of sludge flocs and SEM imaging of sludge morphology to reveal the synergism of IMS treatment. A two-step mechanism of oxidation and Fe(III)-based re-flocculation could be a possible explanation for the synergetic effect of IMS materials treatment. This novel recycle-based IMS composite approach shed light on a new management route for industrial solid wastes while improving efficiency on sludge dewatering.

Keywords: Waste management, advanced oxidation, ZVI, carbon resource utilization, sludge reduction