Non-CO2 Greenhouse Gas Release from Different Biological Wastewater Treatment Processes

Abstract

Methane (CH4) and nitrous oxide (N2O) are two of the most important non-CO2 greenhouse gases. And municipal sewage treatment plant is an important anthropogenic source of CH4 and N2O. Therefore, it is essential to measure the production and emission of CH4 and N2O during biological wastewater treatment process. The surface emission flux isolation chamber was employed to collect the gas sample from the Xi'an No.3 WWTP (the Orbal oxidation ditch process) and Xi'an NO.4 WWTP (A/A/O process) to determine the contents of methane and nitrous oxide. And the effects of temperature and dissolved oxygen concentration on non-CO2 greenhouse gases emission from Xi'an NO.4 WWTP were discussed. The results showed that methane and nitrous oxide emission factors from No.3 WWTP were 1181 mg CH4 per m3 influent and 36.20 mg N2O per m3 influent, respectively while those from the No.4 WWTP were 209 mg CH4 per m3 influent and 54.64 mg N2O per m3 influent. In addition, the important influencing factors which affected methane and nitrous oxide emission were temperature, aeration strategy, DO, nitrite oxidation rate and specific methanogenic activity.