A review on valorization of oyster mushroom and waste generated in the mushroom cultivation industry.

A review of valorization of oyster mushroom species and waste generated in the mushroom cultivation is presented, with a focus on the cultivation and valorization techniques, conditions, current research status and particularly the hazard mitigation and value-added recovery of the waste mushroom substrate (WMS) - an abundant waste in mushroom cultivation industry. Based on the studies reviewed, the production rate of the present mushroom industry is inadequate to meet market demands. There is a need for the development of new mushroom cultivation methods that can guarantee an increase in mushroom productivity and quality (nutritional and medicinal properties). This review shows that the cylindrical baglog cultivation method is more advantageous compared with the wood tray cultivation method to improve the mushroom yield and cost efficiency. Approximately 5 kg of potentially hazardous WMS (spreading diseases in mushroom farm) is generated for production of 1 kg of mushroom. This encourages various valorization of WMS for use in agricultural and energy conversion applications, mainly as biocompost, plant growing media, and bioenergy. The use of WMS as biofertilizer has shown desirable performance compared to conventional chemical fertilizer, whilst the use of WMS as energy feedstock could produce cleaner bioenergy sources compared to conventional fuels.

Applying microwave vacuum pyrolysis to design moisture retention and pH neutralizing palm kernel shell biochar for mushroom production.

Microwave vacuum pyrolysis of palm kernel shell was examined to produce engineered biochar for application as additive in agriculture application. The pyrolysis approach, performed at 750 W of microwave power, produced higher yield of porous biochar (28 wt%) with high surface area (270 cm2/g) compared to the yield obtained by conventional approach (<23 wt%). Addition of the porous biochar in mushroom substrate showed increased moisture content (99%) compared to the substrate without biochar (96%). The mushroom substrate added with biochar (150 g) was optimal in shortening formation, growth, and full colonization of the mycelium within one month. Using 2.5% of the biochar in mushroom substrate desirably maintained the optimum pH level (6.8-7) during the mycelium colonization period, leading to high mycelium growth (up to 91%) and mushroom yield (up to 280 g). The engineered biochar shows great potential as moisture retention and neutralizing agent in mushroom cultivation.

Production of bio-fertilizer from microwave vacuum pyrolysis of palm kernel shell for cultivation of Oyster mushroom (Pleurotus ostreatus).

Microwave vacuum pyrolysis of palm kernel shell (PKS) was performed to produce biochar, which was then tested as bio-fertilizer in growing Oyster mushroom (Pleurotus ostreatus). The pyrolysis approach produced biochar containing a highly porous structure with a high BET surface area of up to 270m2/g and low moisture content (≤10wt%), exhibiting desirable adsorption properties to be used as bio-fertilizer since it can act as a housing that provides many sites on which living microorganisms (mycelium or plant-growth promoting bacteria) and organic nutrients can be attached or adsorbed onto. This could in turn stimulate plant growth by increasing the availability and supply of nutrients to the targeted host plant. The results from growing Oyster mushroom using the biochar recorded an impressive growth rate and a monthly production of up to about 550g of mushroom. A shorter time for mycelium growth on one whole baglog (21days) and the highest yield of Oyster mushroom (550g) were obtained from cultivation medium added with 20g of biochar. Our results demonstrate that the biochar-based bio-fertilizer produced from microwave vacuum pyrolysis of PKS shows exceptional promise as growth promoting material for mushroom cultivation.