title: Direct emissions of N2O, CO 2, and CH 4 from A/A/O bioreactor systems: impact of influent C/N ratio.
abstract: Direct emissions of N2O, CO2, and CH4, three important greenhouse gases (GHGs), from biological sewage treatment process have attracted increasing attention worldwide, due to the increasing concern about climate change. Despite the tremendous efforts devoted to understanding GHG emission from biological sewage treatment process, the impact of influent C/N ratios, in terms of chemical oxygen demand (COD)/total nitrogen (TN), on an anaerobic/anoxic/oxic (A/A/O) bioreactor system has not been investigated. In this work, the direct GHG emission from A/A/O bioreactor systems fed with actual sewage was analyzed under different influent C/N ratios over a 6-month period. The results showed that the variation in influent carbon (160 to 500 mg/L) and nitrogen load (35 to 95 mg/L) dramatically influenced pollutant removal efficiency and GHG production from this process. In the A/A/O bioreactor systems, the GHG production increased from 26-39 to 112-173 g CO2-equivalent as influent C/N ratios decreased from 10.3/10.7 to 3.5/3.8. Taking consideration of pollutant removal efficiency and direct biogenic GHG (N2O, CO2, and CH4) production, the optimum influent C/N ratio was determined to be 7.1/7.5, at which a relatively high pollutant removal efficiency and meanwhile a low level of GHG production (30.4 g CO2-equivalent) can be achieved. Besides, mechanical aeration turned out to be the most significant factor influencing GHG emission from the A/A/O bioreactor systems.
authors: Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan, People's Republic of China.
authors: Yangang
authors: Y
authors: Ren
authors: Jinhe
authors: J
authors: Wang
authors: Li
authors: L
authors: Xu
authors: Cui
authors: C
authors: Liu
authors: Ruiqiang
authors: R
authors: Zong
authors: Jianlin
authors: J
authors: Yu
authors: Shuang
authors: S
authors: Liang
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D002244:Carbon / Q000032:analysis; D002245:Carbon Dioxide / Q000032:analysis*; D008697:Methane / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis; D009609:Nitrous Oxide / Q000032:analysis*; D012722:Sewage; D014865:Waste Disposal, Fluid
chemical_list: D000393:Air Pollutants; D012722:Sewage; D002245:Carbon Dioxide; D002244:Carbon; D009609:Nitrous Oxide; D009584:Nitrogen; D008697:Methane