[Non-CO2 Greenhouse Gas Release from Different Biological Wastewater Treatment Processes]
Hui-Juan Li1, Dang-Cong Peng1, Wen-Bo Liu1
1School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
Huan Jing Ke Xue= Huanjing Kexue
|July 3, 2018
Summary
Municipal wastewater treatment plants emit methane and nitrous oxide. This study measured these greenhouse gases, finding varying emission factors and identifying temperature and dissolved oxygen as key influencing factors.
Area of Science:
- Environmental Science
- Environmental Engineering
- Atmospheric Chemistry
Background:
- Methane (CH4) and nitrous oxide (N2O) are significant non-CO2 greenhouse gases.
- Municipal wastewater treatment plants are a notable anthropogenic source of CH4 and N2O emissions.
- Accurate measurement of CH4 and N2O production and emission during biological wastewater treatment is crucial.
Purpose of the Study:
- To quantify methane (CH4) and nitrous oxide (N2O) emissions from two municipal wastewater treatment plants (WWTPs) in Xi'an.
- To investigate the influence of operational parameters, such as temperature and dissolved oxygen (DO) concentration, on greenhouse gas emissions at the Xi'an NO.4 WWTP (A/A/O process).
Main Methods:
- Utilized surface emission flux isolation chambers to collect gas samples from WWTPs.
- Analyzed gas samples to determine the concentrations of methane (CH4) and nitrous oxide (N2O).
- Correlated gas emissions with environmental factors like temperature and dissolved oxygen (DO).
Main Results:
- Methane and nitrous oxide emission factors for Xi'an No.3 WWTP (Orbal oxidation ditch) were 1181 mg CH4/m³ and 36.20 mg N2O/m³.
- Methane and nitrous oxide emission factors for Xi'an No.4 WWTP (A/A/O process) were 209 mg CH4/m³ and 54.64 mg N2O/m³.
- Temperature, aeration strategy, DO, nitrite oxidation rate, and specific methanogenic activity significantly impacted CH4 and N2O emissions.
Conclusions:
- Wastewater treatment processes significantly contribute to CH4 and N2O emissions.
- Emission factors vary between different treatment processes (Orbal vs. A/A/O).
- Optimizing operational parameters like temperature and DO can mitigate greenhouse gas emissions from WWTPs.
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