Study On Greenhouse Gas Accounting And Emission Reduction Potential Of Wastewater Treatment Plants

In the process of wastewater treatment,a lot of greenhouse gases such as CO₂,CH₄ and N₂O will be released while reducing pollutants in wastewater.This paper briefly introduces the global background of greenhouse gas emission and the development of wastewater treatment in China.Under these two backgrounds,greenhouse gas emission accounting and emission reduction potential of wastewater treatment plants were studied.?1?The process of wastewater treatment is a combine process of physical purification,chemical purification and biochemical purification.The concept model of greenhouse gas emission was introduced to reflect the greenhouse gas emission in wastewater treatment process.The biological sources of CO₂ in wastewater treatment process are mainly catabolism and anabolism of microorganisms.CH₄ was a metabolite produced by microbiodegradation of complex organic pollutants in an anaerobic environment.The production of N₂O was mainly concentrated in nitrification process and denitrification process.The temperature,pH and concentration of organic matter of wastewater all affect the release of CO₂,CH₄ and N₂O.?2?There were three main GHG accounting methods:emission factor method,mass balance method and measurement method.By comparing the three methods and combining the actual situation,the emission factor method was chosen as the main method.Two accounting models by using emission factor method were selected,and a calculator was made to account the greenhouse gas emissions of sewage treatment in example 1,example 2,and example 3.Recycling CH₄ can effectively reduce greenhouse gas emissions.?3?According to the accounting,the COD removal process is the largest emission source of greenhouse gases in example 1 and Example 3,and the same accounting model is adopted for them.The main emission sources of greenhouse gases in example 2 were the power consumption of equipment operation and the emission of CH₄.The adjustment of power grid energy structure reduces greenhouse gas emission by reducing emission factors.The greenhouse gas emission could be reduced by upgrading the wastewater treatment process or adjusting the operation parameters.CH₄ recycling,hydrogen production from wastewater and acid production from wastewater reduce greenhouse gas emissions and realize resource utilization at the same time.Cities of different sizes can also reduce greenhouse gas emissions by choosing suitable sewage treatment models.