Ultrasonication-enhanced biogas production in anaerobic digestion of waste active sludge: A pilot scale investigation

In this study, long-term pilot experiments were conducted to investigate the effects of ultrasonication (US) pretreatment on anaerobic digestion (AD) performance. Life cycling assessment (LCA) was used to assess energy efficiency and environmental impacts. With the response to 90-s US at 0.8 W/mL, the soluble COD concentrations increased by 359.0%, whereas the sludge particle size decreased by 56.7%. The positive effects of US increased biogas production by 15.0% and 25.6% at raw sludge VS/TS averages of 0.60 and 0.43, respectively. LCA results indicated that energy neutralization for US-AD was feasible, with a total energy balance of 461.3 kW center dot h/t DS because of increased energy recovery. The use of US pretreatment allowed for a more diverse microbial community in AD, thereby improving resilience to environmental fluctuations. Unfortunately, US-AD exhibited weak efficiency in inactivating pathogens and antibiotic resistance genes (ARGs), and US could hardly improve the AD control of pathogens carrying ARGs.