The Method And Model Research Of GHG Accounting Of Urban Sewage Treatment System

Recently, climate change had attractted much attentionof the social from all walksof life, to fight climate change, various countries had made corresponding greenhousegas reduction plan. Our country plan to reduce17%GHG emission in2015compared to2010.Urban sewage treatment system is a larger dispersion of GHG emission sources,according to the statistics, from2003to2009, GHG emission from the wastewatertreatment process was increasing year by year, the GHG wmission was53million tonsof CO₂equivalent in2003and75million tons of CO₂equivalent in2009, the annualaverage growth rate was5.95%. Therefore, the GHG emission from urban sewagetreatment system could not to be ignored.In view of the situation of high GHG emission from sewage treatment system,scholars at home and abroad had carried out the research of GHG accounting methodsof wastewater treatment system, based on the methodology by IPCC Guidelines forNational Greenhouse Gas Inventories. But the emission factors defined by the IPCCwere calculated by foreign statistical data, did not fully apply to the sewage treatmentsystem in our country, and the factor were ranged broadly, were suitable for all kinds ofprocessing technology and scale, so the method by IPCC did not have perfect pertinenceand operability.To puts forward the GHG accounting method of sewage treatment system, the pathof all kinds of greenhouse gas emission was analyzed, the main research content andconclusions included:①GHG emission from urban wastewater treatment systemThe organic cycle and transformation of sewage treatment system were concluded,through the degration process of the organic matter during the sewage treatment system.Then, the GHG emission from the sewage treatment system was defined to five kinds.The path of each type GHG emission was analysied, and the key factors wereconcluded.②GHG accounting methods of urban sewage treatment systemAccording to the path and key factors of each kinds of GHG emission from urbanwastewater system, the accounting methods of each kinds of GHG emission were putforward.③Establish and simulation application of GHG accounting method Regard sewage treatment plant as the object, the carbon accounting model ofsewage treatment plant was put forward, and a small-scale sewage treatment plant wastaken to simulation calculation. The results shown that, the GHG emissions of thesewage treatment plant were0.474kg CO₂/t waste water, direct carbon emissions were0.245kgCO₂/t waste water, indirect carbon emissionswere0.229kgCO₂/t waste water;when the biogenic carbon emissions were not included in the calculation; the GHGemissions of the sewage treatment plant were0.595CO₂/t waste water, direct carbonemissions were0.366kgCO₂/t waste water, indirect carbon emissionswere0.229kgCO₂/t waste water; when the biogenic carbon emissions were included in thecalculation.Through the research on GHG accounting of urban sewage treatment system, GHGaccounting methods of sewage treatment system were proposed, which would providethe theoretical basis for quantitative evaluation of ow-carbon technology for urbansewage treatment.