Improving biogas production performance of dairy activated sludge via ultrasound disruption prior to microwave disintegration

Abstract

In this study, ultrasound disruption was employed to enhance the efficiency of microwave disintegration of dairy sludge. Results revealed that ultrasound specific energy input of 1,500 kJ/kg TS was found to be optimum with limited cell lysis at the end of the disruption phase. Biodegradability study suggested an enhancement in suspended solids reduction (16%) and biogas production (180 mL/gVS) in floc disrupted (deflocculated) samples when compared to sole microwave pretreatment (8.3% and 140 mL/gVS, respectively). Energy assessment to attain the 15% optimum solubilization revealed a positive net production of 26 kWh per kg sludge in deflocculated samples compared to 18 kWh in flocculated (sole microwave) samples. Thus, ultrasound disruption prior to microwave disintegration of dairy sludge was considered to be a feasible pretreatment technique.

Effect of low microwave temperature on the physical and chemical properties of waste activated sludge

“…The exact composition of biosludge and the effectiveness of thermal pretreatment can vary depending on factors such as the source of wastewater, the treatment processes used, and the conditions of pretreatment (Al Ramahi et al, 2020). Additionally, by the pretreatment of biosludges while some elements like N, P, K, Na, and Ca might be released in significant quantities, others might not be as readily mobilized or formed compounds that were less soluble (Sun et al, 2013).…”

Effects of the Combined Utilization of Ultrasonic/Hydrogen Peroxide on Excess Sludge Destruction

“…The fast stage is mainly due to the reduction of sludge particle size through destruction, and the extracellular polymer wrapped around the cells is rapidly dissolved in the liquid phase. The slow stage is mainly due to the reduction of easily soluble and decomposable substances in the sludge [40]. In this stage, ultrasound may disrupt exposed cells.…”

Enhancement of biomethane potential of brown sludge by pre-treatment using vortex based hydrodynamic cavitation

“…Acoustic cavitation and microwave have also been used for pre-treatment. However, these processes require significant energy input with adverse impact on cost and environment [ 15 , 16 ]. Hydrodynamic cavitation (HC) refers to a process in which small bubbles or cavities form, expand and subsequently collapse rapidly under ambient conditions.…”