Cradle to Gate
Identity ID
7c4e6bf3-c620-4ea8-bee7-3d6302165e46
Waste treatment
Associated ID
b6e5d37d-c9e4-45d0-8cfe-f20093cf6145
Included activities starts
Included activities ends
Description
The initial sludge (97.5%) is first concentrated and dewatered to reduce its moisture content to 80%. Since the moisture content of the dewatered sludge is still too high for direct use in cement production, it must first be dried to approximately 30% moisture content. The dried sludge can replace part of the sandstone in concrete production; each kg of initial sludge can substitute for 0.0015 kg of sandstone production.
Activity Description
During the treatment process, sludge first undergoes a thickening stage to reduce its volume and increase its solids content. The thickened sludge is then dewatered, where, under the action of flocculants, its moisture content is further reduced. The dewatered sludge is transported to cement plants for use in concrete production. Due to its high moisture content, it cannot be directly used in cement production and requires thermal energy input for drying. The dried sludge is then utilized in concrete preparation, reducing the extraction of raw materials for concrete production, which should also be accounted for 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 using 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. The final dried sludge is utilized in cement production, reducing the consumption of sandstone and achieving the value of waste recycling and reuse.