Relationship between respiratory quotient, nitrification, and nitrous oxide emissions in a forced aerated composting process

摘要

We assessed the relationship between respiratory quotient (RQ) and nitrification and nitrous oxide (N_2O) emission in forced aerated composting using lab-scale reactors. Relatively high RQ values from degradation of readily degradable organics initially occurred. RQ then stabilized at slightly lower values, then decreased. Continuous emission of N_2O was observed during the RQ decrease. Correlation between nitrification and N_2O emission shows that the latter was triggered by nitrification. Mass balances demonstrated that the O_2 consumption of nitrification (～24.8 mmol) was slightly higher than that of CO_2 emission (～20.0 mmol), indicating that the RQ decrease was caused by the occurrence of nitrification. Results indicate that RQ is a useful index, which not only reflects the bioavailability of organics but also predicts the occurrence of nitrification and N_2O emission in forced aerated composting.