Nitrous oxide emissions from a typical northern Chinese municipal wastewater treatment plant

摘要

Nitrous oxide (N_2O) emissions from a typical full-scale tertiary municipal wastewater treatment plant (WWTP) in northern China were investigated during spring and summer of 2010. Results showed that the major emission sources of N_2O performed the following descending order: oxic tanks, final clarifier tanks, anoxic tanks, sludge concentration tanks and anaerobic tanks. The total annual N_2O flux from the oxic tanks was the highest and accounted for the majority of total N_2O emissions of this WWTP. The emission factors derived from the field measurements included per capita emissions of 1.73-2.19 g of N_2O person~(-1) y~(-1) and flow based emissions of 2.37×10~(-5)-3.01×10~(-5) g of N_2O (L of wastewater)~(-1). The N_2O emissions accounted for approximately 0.10%-0.13% of the total nitrogen removed in this WWTP. The most significant factors influencing N_2O emissions in this plant were dissolved oxygen concentration and nitrite concentration in the oxic tanks.