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

Abstract

Continued growth of oil palm cultivation for palm oil production has led to higher post-processing wastes that pose environmental management challenges. The goal of this study was to investigate the co-production of oyster mushroom Pleurotus HK-37 and biogas as a means to add value to palm oil waste fractions and thus reduce their impact on the environment. A total of 9 blends of solid, semi-solid and liquid palm oil waste fractions were subjected to mushroom production and the resulting spent mushroom substrate (SMS) was used for biogas production. There was a significant difference in mushroom yield (t-test, p = 0.00013237) and biological efficiency (t-test, p = 0.00044955), with the highest values obtained from substrate formulation no. 3 (1:1 PMF and EFB (each 49% total weight) supplemented with POME and SD at 1%). Biogas production was also significantly different among both fresh and pretreated (SMS) waste fractions. The highest biogas volume, methane content and methane yield were observed from SMS waste fractions no. 4 (1:1 PMF and EFB (each 44% total weight) supplemented with PPC and PKS at 5% and POME and SD at 1%). Overall, pretreatment of palm oil processing waste with oyster mushrooms increased biogas production and methane yield per kg volatile solids by 102.78% compared to untreated waste. This study has demonstrated that mushroom and biogas production are viable options for the management of palm oil processing waste fractions and thus promoting a circular economy. Further studies should optimize their production and conduct techno-economic