Keywords: microwave temperature, microwave intensity, moisture content, solubilisation, municipal solid waste, organic fraction, pre-treatment, anaerobic digestion, soluble COD, chemical oxygen demand, sCOD, proteins, sugars
Effect of microwave temperature, intensity and moisture content on solubilisation of organic fraction of municipal solid waste
High temperature and pressure microwave (MW) pre-treatment of the Organic Fraction of Municipal Solid Waste (OFMSW) enhanced solubilisation prior to Anaerobic Digestion (AD). Three temperatures (175°C, 145°C and 115°C), three MW intensities based on temperature ramp times (20, 40 and 60 minutes) and two Supplemental Water Additions (SWA) of 20% and 30% were evaluated. MW irradiation resulted in higher concentrations of soluble Chemical Oxygen Demand (sCOD), proteins and sugars in the supernatant phase. The highest level of solubilisation was achieved at 175°C and SWA of 30% and resulted in 1.61, 1.62 and 1.58 times higher sCOD concentrations versus controls for MW intensity ramp times of 20, 40, and 60 minutes, respectively. Additionally, for the same conditions, the free liquid volume released from the OFMSW into the supernatant were observed to be 1.39, 1.34 and 1.37 times greater than the control, respectively. Concomitantly, potentially bio-available sCOD available for AD increased more than two fold compared to control.