LIMITATION IN BIOGAS PRODUCTION FROM CATTLE WASTE DIGESTERS

摘要

To verify if biogas production from cattle waste can be improved by increasing the level of utilizable sugars, daily fed cattle waste digesters - 5.1 operating at a residence time (RT) of 30 days at mesophilic temperature were charged with cattle waste supplemented with cane molasses containing 1.5-7.5% sucrose. Initially, biogas production increased with an increasing concentration of molasses sugar. However, after 4 months, digesters receiving sucrose concentrations higher than 3%, accumulated volatile fatty acids and ceased to produce methane. These acidified digesters could be reactivated only by neutralization and reinoculation. The optimum level of sugar concentration in cattle waste required for optimum gas production was determined to be about 0.2-0.4 % and enhancement of ligno cellulose hydrolysis from cattle waste to yield sugars beyond this level is not desirable.