Cradle to Gate
Identity ID
d423f37b-e1af-4086-862a-3cda4804aa91
Waste treatment
Associated ID
4639c6c1-97dd-454b-9be3-1d34aa74872a
Included activities starts
Included activities ends
Description
Initial sludge (97.5% moisture) is first concentrated and dewatered to reduce the moisture content to 80%, then dried further to reduce the moisture content to 40%, and finally incinerated until all moisture is eliminated, converting the sludge into ash, gas, and thermal energy. Each kg of initial sludge generates 0.025625 kWh of electricity through incineration and produces 0.015 kg of ash. Since sludge incineration ash is pozzolanic and has properties similar to ordinary concrete, it can be used as a supplementary cementitious material in concrete production.
Activity Description
During the treatment process, sludge first undergoes a thickening stage to reduce its volume and increase its solid content. The thickened sludge is then subjected to dewatering, where flocculants are used to further reduce its moisture content. After dewatering, the sludge enters a drying phase, in which thermal energy is applied to reduce moisture, enhancing stability and facilitating subsequent treatment or utilization. Dried sludge is then oxidized through incineration, converting it into ash, gases, and thermal energy. This step eliminates pathogens, reduces sludge volume, and allows for the recovery of thermal energy. Incineration ash can be used in the concrete production process, which reduces the extraction of raw materials for concrete production and should also be considered in the calculations.
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 primarily increases the solids content of sludge through gravity thickeners. Commonly used equipment in the dewatering process includes centrifugal dewatering machines, belt presses, and filter press systems. Sludge drying technologies include direct heating, indirect heating, or a combination of both. The dried sludge is subsequently incinerated, with the main sludge incineration technologies including standalone incineration, co-incineration with municipal solid waste, and co-processing in cement kilns. The incineration ash can be used in the production of concrete, reducing sand consumption and enabling waste recycling and reuse.