Synergistic effect of ultrasonic and microwave pretreatment on improved biohydrogen generation from palm oil mill effluent

Abstract

This study aims to investigate the effect of the ultrasonic, microwave, and combined ultrasonic-microwave pretreatment of palm oil mill effluent (POME) sludge before fermentation to analyze hydrogen (H2) production and chemical oxygen demand (COD) removal efficiency in batch fermentation. Experimental results showed that the pretreatment of sludge (ultrasonication, microwave, and ultrasonication-microwave pretreatment) had positively influence the H2 production and COD removal efficiency during fermentation as compared to control one (without any pretreatment). Combined ultrasonication-microwave pretreatment of POME sludge was shown to be more effective for increasing both H2 production and COD removal from POME with the highest cumulative H2 and COD removal efficiency of 4080 mL H2/L-POME and 75.56%, respectively. The improvement observed for cumulative H2 production and COD removal was 12.14% and 21.42%, respectively, compared to the control one. These observations concluded that the POME sludge pretreatment with ultrasonication-microwave irradiation could be an effective strategy for improved treatment of POME with simultaneous production of H2.