Cradle to Gate
Identity ID
73a28c8f-d91e-4465-8abd-4bac02ce5589
Waste treatment
Associated ID
70b39594-664b-4755-84b7-5dd8165bebd6
Included activities starts
Included activities ends
Description
Primary sludge (97.5% water content) is first thickened to reduce moisture content to 95%. The thickened sludge then undergoes anaerobic digestion, a process that generates biogas which can be recovered and used as an energy source. The digestate residue from anaerobic digestion is ultimately disposed of through land application. For each kg of primary sludge, the greenhouse gas emissions from the anaerobic digestion process are as follows: 0.00225 kg of CH4, 0.00016625 kg of NH₃; 1.03125 kg of COD in the leachate; and recoverable electrical energy of 0.0111125 kWh.
Activity Description
During the treatment process, sludge first undergoes a thickening stage to reduce its volume and increase its solids content. The thickened sludge then enters anaerobic digestion, where anaerobic microorganisms break down organic matter in the sludge, producing biogas for energy recovery while reducing sludge volume and enhancing its stability. The sludge after anaerobic digestion can be used for land application, improving soil structure and providing nutrients necessary for plant growth.
Process Description
"Sewage sludge" is a byproduct generated during the urban wastewater treatment process. 100% sewage sludge, with a moisture content of 97%. 5%, "sludge" consists of the following components: microorganisms, animal and plant residues, inorganic minerals, potential heavy metals, micropollutants, and pathogens. Treatment methods for this by-product include sanitary landfilling, municipal incineration, and use as a raw material for clinker production. Additionally, sludge can be converted into bioenergy through anaerobic digestion or applied to land following stabilization. In the HiQ database, treatment methods for this by-product include incineration, landfilling, aerobic composting, anaerobic digestion, wet oxidation, pyrolysis/hydrothermal carbonization, and land application. Furthermore, this by-product is utilized in the following processes: clinker production, among others.
Time period
2022
2026
Geography
China
Geography comment
National statistics, literature research
Macroeconomic value
Business-as-Usual
Data validation
Yes
Technology
Current Technology
Technology comment
In China's sludge treatment processes, the thickening stage mainly increases the solids content of sludge through gravity thickeners. The anaerobic digestion stage employs anaerobic microorganisms to decompose organic matter in sludge. This biological treatment method not only reduces sludge volume but also recovers energy through biogas production. In the land application stage, sludge treated by anaerobic digestion and stabilization is used for landscaping or soil improvement. This form of resource recovery helps enhance soil structure and provides nutrients necessary for plant growth.