The influence of aeration rate on intermittent forced-aeration composting of biogas residue

An experiment was conducted to study the effect of aeration rates of 0.2, 0.5, 0.8L/(min·kg OM) on intermittent forced-aeration composting of biogas residue. Characteristics of physics, chemistry and maturity were determined during the composting. The results were manifested that the higher aeration rate of 0.8 L/(min·kg OM) did not maintain a longer thermophilic phase. The decomposition rate of OM were 28.2%, 32.9% and 30.5%, respectively. The aeration rate had little influence on the final pH and EC, all composts had reached acceptable optimum values and EC had not exceeded 4mS/cm. The final ammonia nitrogen content in pile of aeration rates of 0.2L/(min·kg OM) did not meet the limit value of 400 mg/kg, and the nitrate nitrogen was 2545, 3146 and 2735 mg/kg, respectively. The final C/N was 16.5, 14.1 and 15.6, and the final germination index (GI) was 92.2%, 96.6% and 82.7%, respectively. The pile of middle aeration rates of 0.5L/(min·kg OM) had the highest humification because E465/E665 (E₄/E₆) of it reduced the largest range. Overall, aeration rates of 0.5L/(min·kg OM) can be chosen for composting.