Cradle to Gate
Identity ID
59801800-0373-4406-b2b7-e0bac4d0df0f
Waste treatment
Associated ID
a9a3637f-400f-4214-9306-1e8764a3bd10
Included activities starts
Included activities ends
Description
The initial sludge (95% moisture content) is first thickened and then dewatered via centrifugation with the addition of polyacrylamide (PAM), reducing its moisture content to 75%. The removed water is treated with a certain amount of FeCl3 and discharged after meeting regulatory standards. The dewatered sludge is semi-dried in a fluidized bed, reducing the moisture content to 40%. The dried sludge is then incinerated separately in a waste-to-energy plant, where the thermal energy generated from combustion is converted into electricity for energy recovery. The ash residue from sludge incineration is transported to a landfill for final disposal. The landfill's lining plate is covered with a low-density polyethylene (LDPE) membrane, which has a low permeability coefficient. Each kg of raw sludge can generate 0.0365555 kWh of electricity through incineration, producing 0.041128 kg of ash residue. The ash residue is transported to a landfill for disposal. Nitrogen (N), phosphorus (P), and heavy metals in landfill leachate are released into water bodies, causing pollution.
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 proceeds to dewatering, where, with the aid of flocculants, its moisture content is further reduced. The separated water is treated with flocculants and discharged after meeting regulatory standards. The dewatered sludge enters the drying phase, where thermal energy is applied to reduce moisture, making it more stable and suitable for subsequent treatment or utilization. During incineration, dried sludge is oxidized, converting into ash, gases, and thermal energy; this step eliminates pathogens, reduces sludge volume, and allows for energy recovery. The residual ash from incineration is sent to a landfill for final disposal. The landfill's impermeable layer uses polyethylene material, which has a low permeability coefficient to prevent pollutants from entering the environment.
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 the sludge through gravity thickeners. Commonly used equipment in the dewatering stage includes centrifugal dewatering machines, belt presses, and plate-and-frame filter presses. Sludge drying technologies involve direct heating, indirect heating, or a combination of both. Dried sludge is subsequently incinerated, with incineration technologies mainly comprising standalone incineration, co-incineration with municipal solid waste, and co-processing in cement kilns. Landfilling, as a final disposal method for sludge, requires pre-treatment of the sludge to reduce its volume and enhance stability before landfilling. The incineration process is widely used due to its high degree of volume reduction and harmlessness, as well as thorough treatment. Landfills need to be equipped with anti-seepage, drainage, and gas collection systems to prevent environmental pollution.