Current Situation And Development Trend Of Urban Sludge Disposal In China Based On Carbon Emission Reduction Analysis

China has a large population and a huge amount of urban sewage.By the end of 2019,there were 5,476 sewage treatment plants nationwide,with an annual cumulative treatment capacity of 656.5 × 108 m3 and an annual sludge production capacity of 39.23 million tons(80% moisture content).With the increase in the number of urban sewage plants,sludge output continues to rise.Fully understanding the current status and development of sludge treatment and disposal and the distribution of carbon emissions is necessary for the future planning and development of the sludge industry.Based on the data of sludge treatment and disposal in China from 2007 to 2019,this paper defined the research boundary of sludge treatment and disposal carbon emissions and calculated the carbon emissions of different sludge treatment and disposal processes according to the methods given by IPCC or obtained through literature review.According to the calculation,carbon emissions per ton of dry sludge anaerobic digestion + land use,aerobic composting + land use,sanitary landfill,incineration,and building materials used are 960.19 kg CO2-eq/t,731.38 kg CO2-eq/t,1587.59 kg CO2-eq/t,2341.36 kg CO2-eq/t and 1239.61 kg CO2-eq/t,respectively.The carbon emission inventory of sludge treatment and disposal from 2007 to 2019 was constructed,and the carbon emission of sludge treatment and disposal in China in 2030 was predicted,and relevant policy Suggestions were given.The number of wastewater treatment plants and sludge production in various provinces,regions and regions are increasing.In 2007,the province with the largest number of wastewater treatment plants was Jiangsu Province(172),and in 2019,the province with the largest number of wastewater treatment plants was Guangdong Province(581).In 2007,the province with the largest sludge production was Shanghai(6.10×106 t),and the province with the largest sludge production in 2019 was Shandong(3.87×106 t).In 2019,the annual sludge production in the seven major regions are: East China(1.44×107t)>North China(6.33×106t)>Central China(4.59×106t)>South China(4.24×106 t)>Southwest(3.59×106 t)>Northwest(3.11×106 t)>Northeast(2.95×106 t).In 2019,the total disposal volume of sludge in the country was 39.0475 million tons,of which land disposal,incineration,construction material utilization and sanitary landfill disposal were 114.023 million tons,10.4231 million tons,6.189 million tons,and 7.803 million tons,respectively.In 2019,the carbon emissions from sludge land use in Beijing and Shandong accounted for a relatively large amount,accounting for 13.14%(250,800 tons CO2-eq)and 12.05%(230,000 tons CO2-eq);Shanghai and Henan provinces account for a relatively large amount of carbon emissions from sanitary landfills,accounting for 10.99%(273.9 thousand tons CO2-eq)and 7.75%(193.3 thousand tons)CO2-eq);Zhejiang Province and Jiangsu Province and other provinces,regions and municipalities accounted for a relatively large amount of carbon emissions from sludge incineration,accounting for 27.02%(1.3186 million tons of CO2-eq)and 19.92%(972,000 Tons CO2-eq).Guangdong Province,Shandong Province and other provinces,autonomous regions and municipalities account for a relatively large amount of carbon emissions from sludge building materials,accounting for 24.39%(370,500 tons CO2-eq)and 9.49%(145.9 thousand tons CO2-eq).Overall,in 2019,Zhejiang,Jiangsu,and Shandong all contributed more than 10% of their carbon emissions,and the three provinces together accounted for about 34.97% of the total carbon emissions from sludge disposal in 2019.It is predicted that by 2030,my country’s annual sewage output will be 94.2416 billion m3,the annual sludge output will be 56544967 tons,the proportion of sludge treatment and disposal will reach 100%,so the annual sludge disposal volume will be 56544967 tons.The amount of sludge used for sanitary landfill,land use,incineration,building material utilization,and other disposals are: 5654497 ± 2827248 tons,19790738 ± 2827248 tons,14136242 ± 2827248 tons,14136242 ± 2827248 tons,2827248 ± 2827248 tons,sludge The carbon emissions from landfill,land use,incineration,and building material utilization are: 1.80 ± 0.89 million tons of CO2-eq,2.89± 0.41 million tons of CO2-eq,6.62 ± 1.32 million tons of CO2-eq,3.51 ± 0.70 million tons of CO2-eq.Overall,by 2030,the overall sludge treatment and disposal situation will be similar to the sludge treatment and disposal situation in developed European countries in 2017.