Estimating nitrous oxide emissions based on TN discharge from municipal wastewater treatment plants: A case study for the city of Xiamen, China

Mitigation of nitrous oxide (N₂O) emissions is of primary importance to meet the targets of reducing carbon footprints of wastewater treatment plants (WWTPs). This paper takes the N₂O discharged from a case study of wastewater treatment plants as the main research object, and then develops a novel algorithm, which can accurately estimate the amount of N₂O release, and then applies it to the local wastewater treatment plants. According to the results, the nitrous oxide emission flux and the emission factors (EFs) are discussed. The results include the following: (1) The total amount of N₂O discharged from Xiamen wastewater treatment plants between 2018 and 2019 was 3881.29 kg and 3642.97 kg, respectively; (2) the production of N₂O emissions based on the total nitrogen (TN) algorithm in the existing wastewater treatment factories in Xiamen was obtained based on the research EFs; and (3) by controlling other factors of WWTPs process such as chemical oxygen demand /nitrogen (COD)/ (N) ratio, dissolved oxygen (DO) concentration, pH value (the degree of concentration of hydrogen ions), and solids retention time (SRT) in the wastewater treatment process, selecting a secondary wastewater treatment process with an economical and reasonable approach can reduce N₂O emissions in the wastewater treatment process. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.