Enhancement of Kelowna's biosolids to energy conversion with thermal pretreatments

The potential of using biogas generated from organic waste as energy source is broadly recognized and anaerobic digestion has become a major part of modern wastewater treatment plants (WWTPs). Various pretreatment techniques have been recently developed to increase the quantity of biogas and reduce digester volume by enhancing the hydrolysis of waste material fed to the digesters. This study evaluates advanced anaerobic digestion incorporating thermal pretreatments (microwave at 2.45 GHz and conventional heating) as an alternative disposal method for the municipal biosolids generated by Kelowna WWTP (BC, Canada) which are currently composted. To be able to compare microwave irradiation with conventional heating under identical conditions (temperature/ heating rates), a custom pressure vessel was built for conventional heating. Biosolids heated from room temperature up to pretreatment temperatures of 80, 120 and 160oC at heating rate of (7.5oC/min) in the closed vessel microwave unit and the pressure sealed vessel. Both conventional heating and microwave pretreatments indicated that in a pretreatment range of 80-160oC, temperature was a statistically significant factor (p