Study on the Factors Influencing COD Removal Rate of Cattle Manure Anaerobic Fermentation

The influence of liquor concentration, temperature and sludge amount on COD removal rate of cattle manure anaerobic fermentation from 20 degrees C to 30 degrees C were studied with the experimental design of quadratic rotatable regression. The ranges of liquor concentration, temperature and sludge amount were from 4% to 12%, from 20 degrees C to 30 degrees C and from 0% to 40% respectively. Frequency analysis was used to find the optimal experimental parameter space. The single-parameter analysis and the double-parameter analysis were used to analyze the main-sub order of every parameter in quadratic nonlinear model and the influence of every parameter on COD removal rate. The results showed that the optimal experimental parameter space of liquor concentration, temperature and sludge amount were from 6% to 9%, from 28 degrees C to 30 degrees C and from 24% to 35% respectively. The effect of temperature on COD removal rate was the greatest, sludge amount and liquor concentration were the second and third effective ones. The COD removal rate first increased and then decreased with increasing liquor concentration, first decreased and then increased with raising temperature and first increased and then decreased with increasing sludge amount.