Valorization of palm oil wastes into oyster mushrooms (Pleurotus HK-37) and biogas production

The study explored the potential of co-production of oyster mushroom Pleurotus HK-37 and biogas from palm oil waste fractions to add value and mitigate environmental impact. Nine different blends of waste fractions were subjected to mushroom production. The highest mushroom yield and biological efficiency were obtained from a blend that combined equal amounts of palm mesocarp fiber (PMF) and empty fruit bunch (EFB) waste fractions supplemented with 1% palm oil mill effluent (POME) and sediments (SD). The spent mushroom substrates (SMS) were used in biogas production, compared to fresh waste blends, biogas volume was higher across all but two treatments. Substrate formulation no. 3 (1:1 PMF and EFB (each 49% total weight) supplemented with POME and SD at 1%) showed the highest mushroom yield, biological efficiency and mushroom size while spent mushroom substrate formulation number. The highest biogas and methane volumes were from SMS that was a blend of equal parts PMF and EFB supplemented with 1% POME and SD, and 5% palm press cake and palm kernel shells. The highest increase of biogas volume and methane yield observed as a result of pretreatment of the palm oil waste fractions through mushroom cultivation was 102.78%. These findings show that co-production of mushrooms and biogas is a potential solution to managing palm oil waste and promoting a circular economy. Future research should establish economic feasibility of the process.