Novel electro-dewatering system for activated sludge biosolids in bench-scale, pilot-scale and industrial-scale applications

Abstract

To optimize the economics of electro-dewatering system in a new multi-layer vertical electric field for activated sludge biosolids, different-sized experiments were carried out in this study, including bench-scale, pilot-scale and industrial-scale applications. A bench-scale system was established to determine the optimal parameters of the new structure, including the mechanical pressure level, dewatering extent, processing time and sludge cake thickness. Then, a pilot-scale automated electro-dewatering system was developed to investigate the cathode fouling problems during continuous operations. A complete industrial-scale electro-dewatering system was established with 80t/d of sludge dewatering capacity based on the above work. The operational stability, the service life of the core parts and the economics were evaluated during a long time operating. Under various optimized parameters and control modes, 69% of the moisture in mechanically dewatered sludge could be reduced within 7–8min. The average energy consumption was 0.123kWh/kgdewater at 41kgdewater/(m2h) of anode processing capacity and the anode side temperature was lower than 65°C, when the anode utilization efficiency was 88.2%. The industrial-scale tests with optimized parameters demonstrated considerable economic benefits.