Hong Jinglan, Hong Jingmin, Otaki Masahiro, Jolliet Olivier
Department of Environmental Health Science, School of Public Health, University of Michigan, 109 South Observatory, Ann Arbor, MI 48109, USA.
Waste Manag. 2009 Feb;29(2):696-703. doi: 10.1016/j.wasman.2008.03.026. Epub 2008 Jul 22.
Life cycle assessment for sewage sludge treatment was carried out by estimating the environmental and economic impacts of the six alternative scenarios most often used in Japan: dewatering, composting, drying, incineration, incinerated ash melting and dewatered sludge melting, each with or without digestion. Three end-of-life treatments were also studied: landfilling, agricultural application and building material application. The results demonstrate that sewage sludge digestion can reduce the environmental load and cost through reduced dry matter volume. The global warming potential (GWP) generated from incineration and melting processes can be significantly reduced through the reuse of waste heat for electricity and/or heat generation. Equipment production in scenarios except dewatering has an important effect on GWP, whereas the contribution of construction is negligible. In addition, the results show that the dewatering scenario has the highest impact on land use and cost, the drying scenario has the highest impact on GWP and acidification, and the incinerated ash melting scenario has the highest impact on human toxicity due to re-emissions of heavy metals from incinerated ash in the melting unit process. On the contrary, the dewatering, composting and incineration scenarios generate the lowest impact on human toxicity, land use and acidification, respectively, and the incinerated ash melting scenario has the lowest impact on GWP and cost. Heavy metals released from atmospheric effluents generated the highest human toxicity impact, with the effect of dioxin emissions being significantly lower. This study proved that the dewatered sludge melting scenario is an environmentally optimal and economically affordable method.
通过评估日本最常用的六种替代方案（脱水、堆肥、干燥、焚烧、焚烧灰熔融和脱水污泥熔融，每种方案有无消化处理）的环境和经济影响，对污水污泥处理进行了生命周期评估。还研究了三种最终处置方法：填埋、农业应用和建筑材料应用。结果表明，污水污泥消化可以通过减少干物质体积来降低环境负荷和成本。通过将废热再利用来发电和/或供热，可以显著降低焚烧和熔融过程产生的全球变暖潜能值（GWP）。除脱水方案外，其他方案中的设备生产对GWP有重要影响，而施工的贡献可忽略不计。此外，结果表明，脱水方案对土地利用和成本的影响最大，干燥方案对GWP和酸化的影响最大，焚烧灰熔融方案由于熔融单元过程中焚烧灰中重金属的再排放而对人体毒性影响最大。相反，脱水、堆肥和焚烧方案分别对人体毒性、土地利用和酸化的影响最小，焚烧灰熔融方案对GWP和成本的影响最小。大气排放物中释放的重金属对人体毒性影响最大，二噁英排放的影响明显较低。本研究证明，脱水污泥熔融方案是一种环境最优且经济可行的方法。
