Effect of Ultrasonic and Sonothermal Treatment on Weight Reduction and Particles Size Distribution of Raw Palm Oil Mill Effluent (POME)

Abstract

Thetemperature rise during ultrasonic and sonothermal pretreatments had induced the volatilisationof wastewater prior to anaerobic digestion process. In this study,wastewater from palm oil mill which is known as raw palm oil mill effluent (POME) was exposed to ultrasonic irradiation by using an ultrasonic bath at the rate of 37 kHz. Effects ofultrasonic and sonothermaltreatments onphysical properties of raw POME as a result of the volatilisation process were investigated through these analyses: weight reduction, particle sizedistribution and Specific Surface Area (SSA). The weight reduction was observed to be increased by 39.05% after 6 hours ofultrasonic exposure due to volatilisation process in aqueous phase.The combined sonothermal at a temperature of 75oC resulted in the highest weight reduction, 19%, compared to lower sonothermal temperatures of 45oC, 55oC and 65oC after 1 hour treatment. Looking at particle size distributions after the treatment, the process reduce the Average Particle Size, D[4,3](or de Brouckere mean diameter) while making the SSAincrease, both rather significantly. However, there were slight increase observed in D[4,3] and areduction in SSA after 3 hours of ultrasonic treatment. This is mostly due to thereflocculation process during the ultrasonic treatment. In contrast, an hour ofsonothermaltreatment showed that the D[4,3] of raw POME continuously reduced as the temperature increase from 45oCto 75oC.