Biodegradation of organic wastes to fuel gases by microbial fermentation

Biowastes (e.g. apple pomace, dumping wheat and vegetable wastes), rich in organic substrates have been utilized for producing H₂ and CH₄ by mixed and pure cultures. Mixed culture obtained from cattle dung could generate CH₄ from apple pomace, dumping wheat and vegetable wastes in the range of 157,500 and 218 ml per gram total solids of organic waste degraded respectively. H₂ was generated from apple pomace and dumping wheat only, being 60 ml and 58 ml/g of organic substrate degraded. Pure culture of H ₂ producing bacteria isolated from cattle dung generated 84 ml H₂/g glucose consumed and 30 ml and 42 ml H₂/g apple pomace and dumping wheat fed respectively. Microbial H₂ production was observed to be optimum at temperature of 40°C, pH 6.5-7.0 and a substrate level of 3-6%, whereas optimum CH₄ production occurs at temperature range of 37-40°C, pH 7-8 and substrate level of 3%. These fermentation processes also lead to substantial reduction in the chemical oxygen demand (COD) load of the waste material