基于化石碳的污泥干化焚烧处置碳排放分析

Analysis on carbon emissions of sludge drying and incineration treatment based on fossil carbon

通常认为,污泥焚烧产生的CO^(2)是生物成因,不计入碳排放核算清单。但石油加工化学品的广泛使用会导致污泥化石碳质量分数增加。为符合实际情况,采用放射性碳测年法测定污泥化石碳质量分数。基于浙江省某2500 t·d^(-1)污泥能源化利用热电联产项目运营数据,以1 t干基污泥(DS)为核算对象,构建碳排放及碳补偿核算方法,得出污泥干化焚烧-灰渣综合利用路径的碳排放因子,并与深度脱水-应急填埋路径的理论碳排放水平比较。结果表明,污泥有机碳中化石碳质量分数为64.94%,并非100%的生源碳。因此,污泥焚烧时计入碳排放核算清单的直接碳排放会增大,同时数据准确性和可靠度也有所增加。干化焚烧-灰渣综合利用路径中,1 t干基污泥的碳排放为0.32 tCO^(2eq),约为深度脱水-应急填埋路径的1/6,更具减排潜力。本研究结果可为污泥低碳化处理处置提供参考。

CO^(2)from sludge incineration is commonly considered biogenic and thus excluded from the carbon emission accounting list.However,the widespread use of petroleum processing chemicals would lead to an upward trend in sludge’s fossil carbon mass proportion.To adjust for the current circumstances,the radiocarbon dating technique was employed to quantify the mass fraction of fossil carbon in sludge.Based on the operation data of a 2500 t·d^(-1)sludge energy utilization cogeneration project in Zhejiang Province,carbon emissions and compensation accounting methods were built using 1 t dry base sludge(DS)as the accounting object.The carbon emission factor of the sludge drying incineration-comprehensive utilization of ash and slag path was calculated and compared with the theoretical carbon emission level of the deep dewatering-emergency landfill path.The results revealed that the mass proportion of fossil carbon in sludge organic carbon was 64.94%,indicating that the carbon was not entirely biogenic.As a result,the direct carbon emissions integrated into the carbon emission inventory when incinerating sludge would increase,simultaneously improving the data’s accuracy and dependability.The carbon emission(in terms of CO^(2)-equivalent)of 1 t dry base sludge in the path of drying incineration-comprehensive utilization of ash and slag was 0.32 t,about 1/6 of that in the route of deep dehydration-emergency landfill,which had better emission reduction potential.This research could serve as a reference for sludge low-carbonization treatment and disposal.