Anaerobic degradation of cellulose by mixed culture

Abstract

A mixed culture in which cellulose is capable of being converted to methane and carbon dioxide was obtained from an inoculum procured from a sewage-treatment plant and maintained in a synthetic medium containing tissue paper and an inorganic salt and vitamin mixture. The culture was tested for its ability to degrade 12 different paper and cotton products under batch conditions in 3-ℓ anaerobic fermenters. This culture degraded 6–8 mmol/ℓ per week of cellulose, expressed as glucose equivalents, with total gas yields of 0.3 m3/kg of cellulose degraded. The gas produced contained between 56 and 59% of methane. Maximum cellulose degradation occurred at chemical oxygen demand: nitrogen: phosphorus level of 80:5:1 and was adversely affected by high stirring rate. Also the presence of higher proportions of lignin in cellulose products adversely affected the ability of this culture to degrade cellulose.