Prospects of Utilization of Liquid Fraction of Biogas Digestate as Substrate Supplement for Mushroom Cultivation

Biogas digestate is the by-product of ‘anaerobic digestion’ process that produces biogas as the primary form of energy. Since digestates are the inevitable commodities of the conversion process, means of their appropriate management is essentially required for sustainability of bioenergy system. In developing countries, with faster adoption of biogas technology, a simultaneous increase in biogas residue is also expected drawing attention for their immediate and effective utilization. Since biogas digestate retains nutrients from input feedstock with enhanced bioavailability and minimum variation, these could be potentially used as growth supplement for mushroom. Present study discusses the prospects of utilization of the liquid fraction of biogas digestate as a substrate along with rice straw for enhancing the production of white oyster mushroom (Pleurotus florida) under laboratory conditions. The study investigates the effect of liquid fraction of biogas digestate on yield and growth parameters (stem height, cap diameter, mean weight) of mushroom. An enhancement of yield by 38% was observed under liquid digestate application compared to control using only rice straw as substrate. In addition, cost dynamics analysis also showed feasibility of production of mushroom at commercial scale. Integrated development of biogas technology with subsequent valorization of digestate through mushroom cultivation may help in increasing overall profitability of biogas system.