Cradle to Gate
Identity ID
d108855a-a14c-4fd1-863b-3afb46267a04
Waste treatment
Associated ID
c1b7bbe6-4116-4f89-b8a4-bb4242c1a231
Included activities starts
Included activities ends
Description
Initial sludge (95%) 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 regulatory standards. The dewatered sludge undergoes semi-drying in a fluidized bed, reducing its moisture content to 40%. The dried sludge is then sent to a waste incineration plant for co-combustion, during which combustion heat is converted into electricity, enabling energy recovery. The ash and residues from sludge incineration are transported to a landfill for final disposal. The landfill's impermeable layer is covered with low-density polyethylene (LDPE) film, which has a low permeability coefficient. Per kg of initial sludge, incineration can generate 0.031986 kWh of electrical energy and produce 0.0421815 kg of ash residue. The ash residue is used for preparing construction materials (e.g., cement or bricks).
Activity Description
During the sludge 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 applied to further reduce its moisture content. The separated water is treated with flocculants and discharged after meeting regulatory standards. The dewatered sludge proceeds to the drying phase, where thermal energy is applied to reduce moisture, enhancing stability for subsequent processing or utilization. The dried sludge is then incinerated, undergoing oxidation to produce ash, flue gas, and thermal energy. This step eliminates pathogens, reduces sludge volume, and recovers energy. The residual ash from incineration is utilized in the production of construction materials.
Process Description
During the sludge 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 applied to further reduce its moisture content. The separated water is treated with flocculants and discharged after meeting regulatory standards. The dewatered sludge proceeds to the drying phase, where thermal energy is applied to reduce moisture, enhancing stability for subsequent processing or utilization. The dried sludge is then incinerated, undergoing oxidation to produce ash, flue gas, and thermal energy. This step eliminates pathogens, reduces sludge volume, and recovers energy. The residual ash from incineration is utilized in the production of construction materials.
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. Commonly used equipment in the dewatering process includes centrifugal dewatering machines, belt filter presses, and plate-and-frame filter presses. Sludge drying technologies include direct heating, indirect heating, or a combination of both. Dried sludge is subsequently incinerated, with sludge incineration technologies primarily including standalone incineration, co-incineration with municipal solid waste, and co-processing in cement kilns. Landfilling, as an end-disposal method for sludge, requires pretreatment of sludge prior to landfilling to reduce volume and enhance stability. Due to its advantages such as high volume reduction, high harmless level, and thorough treatment, incineration technology is widely applied. Incineration ash can be used in the production of cement and bricks.