Cradle to Gate
Identity ID
d743918f-1ba5-43a2-ae52-02a3a172d0ff
Waste treatment
Associated ID
d317038c-a122-4683-94bf-03c6c901a127
Included activities starts
Included activities ends
Description
The initial sludge (95% moisture content) is first thickened and then centrifugally dewatered by adding polyacrylamide (PAM) to reduce the moisture content to 75%. The removed water is treated with a certain amount of FeCl3 and discharged after meeting the required standards. The dewatered sludge is directly sent to a kiln incineration plant, where it is mixed with clay, limestone, iron ore, and other materials for incineration to produce gases and cement. Specifically, 1 ton of dry sludge generates 0.3 tons of ash residue, which is incorporated into cement products at a ratio of 10%.
Activity Description
During the treatment process, sludge first undergoes a concentration stage to reduce its volume and increase its solid content. The concentrated sludge is then dewatered, further reducing its moisture content with the aid of flocculants. The removed water is treated with flocculants and discharged after meeting regulatory standards. The dewatered sludge is fed into a cement kiln, where it is co-incinerated with other materials, converting it into combustion residues and gases. This step eliminates pathogens and reduces the volume of the sludge. The resulting residues can be recovered and used as raw material in cement production.
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 uses gravity thickeners to increase the solids content of the sludge. Commonly used equipment in the dewatering stage includes centrifugal dewatering machines, belt press filters, and plate-and-frame filter presses. Sludge drying technologies involve direct heating, indirect heating, or a combination of both. The dried sludge is subsequently incinerated. Sludge incineration technologies mainly include standalone incineration, co-incineration with municipal solid waste, and co-processing in cement kilns. Incineration is widely applied due to its high degree of volume reduction, effective detoxification, and thorough treatment. Incineration in cement kilns can transform sludge and other materials into cement, enabling waste recycling and reuse.