Main content area

Life cycle assessment of an industrial symbiosis based on energy recovery from dried sludge and used oil

Liu, Qiang, Jiang, Peipei, Zhao, Jun, Zhang, Bo, Bian, Huadan, Qian, Guangren
Journal of cleaner production 2011 v.19 no.15 pp. 1700-1708
acidification, air, ammonia, carbon dioxide, coal, drying, energy, energy recovery, environmental impact, environmental performance, eutrophication, global warming, heavy metals, humans, hydrochloric acid, hydrogen sulfide, industrial symbiosis, life cycle assessment, methane, nitrous oxide, oils, operating costs, polycyclic aromatic hydrocarbons, sewage sludge, steam, sulfur dioxide, toxicity, volatile organic compounds, China
Recovering energy from wastes is a useful strategy for integrated waste and energy management in an eco-industrial park (EIP) and gives promising reduction of wastes, total energy consumption and operation cost. In Jinqiao EIP, Pudong New Area, Shanghai, an industrial symbiosis, based on the energy recovery from municipal sewage sludge and re-refined oil, was proposed in the central heat-supplying company of Jinqiao EIP. It is expected that hot off-gas or part of the steam from the central heat-supplying company could be used for sludge drying and used oil re-refining while the dried sludge and refined oil can be partial substitution for fossil fuel. For the purpose of assessing the environmental performance of this industrial symbiosis, life cycle assessment (LCA) was used and different scenarios were set up in this study to evaluate the Global warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), Human toxicity air (HTA) and Total Environmental Impact Potential (TEIP) of the system. Results indicate that when the substitute ratio of coal by sludge is 14%, the proposed industrial symbiosis has the least environmental impact. Compared with the current situation (sludge is landfilled), co-combustion of dried sludge and re-refined oil with coal at optimal scale will release less CO₂, CH₄, NOₓ, N₂O and CO, but more SO₂, H₂S, NH₃, HCl, polycyclic aromatic hydrocarbons (PAHs), non-methane volatile organic compounds (NMVOC) and heavy metals.