This study investigated the effect of bulking agents on the maturity and gaseous emissions of composting
kitchen waste. Three different bulking agents (cornstalks, sawdust, and spent mushroom substrate) were
used to compost kitchen waste under aerobic conditions in 60-L reactors for a 28-d period. A control
treatment was also studied using kitchen waste without a bulking agent. During the experiment, maturity
indexes such as temperature, pH value, C/N ratio, and germination index were determined, and continuous
measurements of leachate and gaseous emissions (CH4, N2O, and NH3) were taken. The results
showed that all of the composts with bulking agents reached the required maturity standard, and the
addition of spent mushroom substrate gave the highest maturity (C/N ratio decreased from 23 to 16
and germination index increased from 53% to 111%). The bulking agents also reduced leachate production
and CH4 and N2O emissions, but had little impact on NH3 emissions. Composting with sawdust as a bulking
agent was found to emit less total greenhouse gas (33 kg CO2-eq t1 dry matter) than the other
treatments.