Feasibility and Carbon Footprint Analysis of Lime-Dried Sludge for Cement Production

Li Ping, Gang Zhao, Xiaohu Lin, Yunhui Gu, Wei Liu, Haihua Cao, Juwen Huang and Jingcheng Xu
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Li Ping: College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
Gang Zhao: College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
Xiaohu Lin: College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
Yunhui Gu: College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
Wei Liu: College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
Haihua Cao: College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
Juwen Huang: College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
Jingcheng Xu: College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China

Sustainability, 2020, vol. 12, issue 6, 1-11

Abstract: Cement manufacturing and the treatment of sludge are considered both energy-intensive industries and major greenhouse gas (GHG) emitters. However, there are still few studies on comprehensive carbon footprint analysis for adding municipal sludge in the cement production. In this study, the lime-dried sludge blended with calcium oxide at the mass mixing ratio of 10% was utilized as raw material for the preparation of Portland cement. The chemical and physical properties of sludge were analyzed. A set of carbon footprint calculation methods of lime-drying treatment of sludge and reuse in cement kilns was then established to explore the feasibility of coprocessing lime-dried sludge in cement kilns. The results showed lime-dried sludge containing CaO, SiO 2 , Al 2 O 3 , and Fe 2 O 3 was ideal for cement production as raw material. However, the water content of lime-dried sludge should be strictly limited. The lime-drying process presented the biggest carbon emission (962.1 kg CO 2 -eq/t sludge), accounting for 89.0% of total emissions. In the clinker-production phase, the lime-dried sludge as raw material substitute and energy source gained carbon credit of 578.8 and 214.2 kg CO 2 -eq/t sludge, respectively. The sludge used for producing cement clinker could reduce carbon emissions by 38.5% to 51.7%. The addition ratio of lime and stacking time in the sludge lime-drying process could greatly affect the carbon footprint of coprocessing lime-dried sludge in cement kiln.

Keywords: wastewater treatment plant; lime-dried sludge; cement production; energy; carbon footprint (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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