Continuously flow microwave pre-treatment for enhanced anaerobic biodegradability of dairy industry sludge

Abstract

Our research has focused on the investigation of the applicability of continuously flow microwave pre-treatment process for anaerobic digestion of dairy industry sludge. In the continuously flow operation effects of microwave specific process parameters, i.e. specific irradiated energy and microwave power level, were examined on the biogas yield and anaerobic digestion rate. Furthermore, the efficiency of process was characterized based on energetic analysis, as well. Our results show, that depend on the irradiated energy level the microwave power has effect on biogas yield, and determine the biodegradation rate, as well. Higher energy irradiation or higher power has been manifested in enhanced anaerobic digestion, but over a certain value of them led to worsened methane content. Considering the results obtained from energetic analysis can be concluded, that microwave pre-treatment followed by anaerobic digestion is efficient if irradiated energy was kept lower level (100 kJ L-1, in present experiments) with microwave power levels of 536 W, or 700W, respectively. Too high energy intensity at high power level, or too low microwave power, independently from the extent of irradiated energy, led to higher energy demand of pre-treatment, than can be recovered as energy content of surplus biogas.