Enhancement of anaerobic digestion efficiency of sludge from urban domestic wastewater treatment plant by pretreatment with Kali hydroxide

Abstract

    With the increasing industrialization and urbanization, the management and disposal of wastewater sludge, especially Waste Activated Sludge (WAS), has become one of the biggest environmental challenges. WAS is an inevitable by-product of biological wastewater treatment in municipal wastewater treatment plants (WWTP). Improper disposal of WAS can cause serious environmental damage due to the high pathogen and organic content in the sludge. This study aimed to develop an efficient KOH pretreatment process, integrating the analysis of mechanism, performance and practical application potential, thereby providing an optimal solution for WAS treatment and energy recovery. The study confirmed that 3-hour alkaline pretreatment with KOH is an effective pretreatment method to enhance the anaerobic digestion of waste activated sludge, resulting in a significant increase in biogas potential. The optimal KOH dosage (0.15 gKOH/gVS) increased the cumulative biogas yield by 34% compared to the control sample. This enhancement was achieved due to the strong disruption of the biomass structure, which increased the sCOD concentration by nearly 5 times. With the obvious biogas enhancement effect and short treatment time (3 hours), this method has the potential for practical implementation to improve the economic and environmental performance of wastewater treatment plants.