Comparative study of sludge thermophilic drying technology under the dual carbon strategy

Carbon emission during the sludge treatment and disposal process is an important source of carbon emission in the sewage treatment industry. The drying process can achieve the reduction and stabilization of sludge, reducing its adverse impact on the environment. Aiming at the problems of reduction and resourceization in the process of municipal sludge treatment, municipal sludge with water content of 40%-80% was taken as the research object, and a multi-dimensional evaluation of the disc drying and low-temperature drying technologies was carried out by comparing and analyzing the working principle, economic cost, carbon emission, and other indexes. The results showed that the low temperature drying technology had better condensate quality, lower wastewater treatment cost, less odor volume and simple composition. Disc drying technology process was mature, adapted to large-scale sludge disposal project, low investment cost, simple structure, small footprint, low performance decay rate, and stable operation. In addition, the carbon emission of low-temperature drying technology for treating per unit mass of sludge was 907.94 kg/t(calculated as CO2-eq), while the carbon emission of disc drying was 1 262.80 kg/t(calculated as CO2-eq). The effect of low-temperature belt drying technology in reducing the pollution and carbon was remarkable.