Cradle to Gate
Identity ID
943b653e-e923-4180-af58-abacc232a91a
Waste treatment
Associated ID
2f086c13-2e13-4853-b638-00223abaf5bb
Included activities starts
Included activities ends
Description
Raw sludge (95%) is first thickened and dewatered via filtration with the addition of FeCl3 to reduce moisture content to 70%. The removed water is treated with a certain amount of FeCl3 and discharged after meeting regulatory standards. The dewatered sludge is then stabilized by adding lime to reduce its moisture content and pathogen levels, minimizing its subsequent environmental impact. The lime-stabilized sludge is transported to a landfill for final disposal, where the impermeable layer is covered with a low-density polyethylene (LDPE) membrane, which has a low permeability coefficient. Landfill masses can generate malodorous substances such as H2S and NH3, while nitrogen (N), phosphorus (P), heavy metals, and persistent organic pollutants (POPs) in leachate can be released into water bodies, causing pollution.
Activity Description
During sludge treatment, it first undergoes gravity or centrifugal thickening to reduce its volume and increase the solid content. The thickened sludge is then dewatered, further reducing its moisture content with the aid of flocculants. The separated water is treated with flocculants and discharged after meeting regulatory standards. The dewatered sludge is stabilized by mixing with a certain amount of lime, effectively suppressing pathogen growth and reducing the release of volatile organic compounds (VOCs). The lime-stabilized sludge is then sent to a landfill for final disposal. The landfill's liner is made of polyethylene material, which has a low permeability coefficient, preventing pollutants from infiltrating into 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 sludge through gravity thickeners. Commonly used equipment in the dewatering stage includes centrifugal dewatering machines, belt presses, and plate-and-frame filter presses. Landfilling, as an end-disposal method for sludge, requires pretreatment before landfilling to reduce volume and enhance stability. Adding lime to dewatered sludge for stabilization can reduce moisture content, eliminate pathogens, and improve sludge stability, facilitating subsequent handling. Landfills must be equipped with anti-seepage, drainage, and gas collection systems to prevent environmental pollution.