College of Environmental Science & Engineering, Tongji University, Shanghai 200092, PR China; Civil & Environmental Engineering Department, University of California, Irvine, CA 92697-2175, USA.
Civil & Environmental Engineering Department, University of California, Irvine, CA 92697-2175, USA; Water-Energy Nexus (WEX) Center, University of California, Irvine, CA 92697-2175, USA.
Sci Total Environ. 2019 May 15;665:762-773. doi: 10.1016/j.scitotenv.2019.02.024. Epub 2019 Feb 4.
Biosolids or sludge management has become an environmental and economic challenge for water resource recovery facilities (WRRFs) and municipalities around the world. The electric energy and operational costs linked to the solid processing stage can account for 20% and 53% of the overall treatment respectively, and as such they are primary factors among utilities which must be considered while working toward more efficient strategies with less energy use. As part of the growing awareness of greenhouse gas (GHG) emissions, municipal wastewater treatment plants have begun reporting their GHG emission inventories. However, there is not yet a standardized or fully comprehensive CFP analysis for the biosolids management. In this paper, two major metropolitan WRRFs in China and the USA with two different biosolids management approaches were compared in terms of energy and carbon footprint (CFP). Site-specific equipment inventories coupled with state-of-the-art methodologies were used for the carbon and energy intensity assessment. Tailored biosolids management strategies and scenarios were included in the analysis to provide a venue for the reduction of their environmental impact. Co-digestion with food waste (FW) and the economic feasibility of its implementation were proposed as a GHGs mitigation strategy to highlight the energy recovery potential. Although both plants had similar energy intensity, Plant A (Shanghai) exhibited three times larger CFP primarily due to site-specific limitations on their biosolids management. The study showed the potential to improve CFP by 28.8% by selecting convenient strategies (i.e., incineration with AD). Energy recovery with its concurrent environmental benefits can be further enhanced by implementing FW co-digestion. This study shows the economic and environmental relevance of selecting adequate biosolids processing strategies and energy recovery practices in WRRFs.
生物固体或污泥管理已成为全球水资源回收设施 (WRRF) 和城市的环境和经济挑战。与固体处理阶段相关的电能和运营成本分别占总处理费用的 20%和 53%，因此它们是公用事业公司在寻求更节能、使用更少能源的策略时必须考虑的主要因素。随着对温室气体 (GHG) 排放认识的不断提高，城市污水处理厂已开始报告其 GHG 排放清单。然而，对于生物固体管理，目前还没有标准化或全面的综合碳足迹 (CFP) 分析。本文比较了中国和美国两个具有不同生物固体管理方法的主要大都市 WRRF 的能源和碳足迹 (CFP)。使用特定于站点的设备清单和最先进的方法进行碳和能源强度评估。定制的生物固体管理策略和方案被纳入分析，以提供减少其环境影响的场所。与食物垃圾 (FW) 共消化和其实施的经济可行性被提出作为一种减少 GHG 的策略，以突出能源回收潜力。尽管两个工厂的能源强度相似，但工厂 A（上海）表现出三倍大的 CFP，主要是由于其生物固体管理的特定地点限制。研究表明，通过选择便捷的策略（即与 AD 一起焚烧），CFP 有潜力提高 28.8%。通过实施 FW 共消化，可以进一步提高能源回收的环境效益。本研究表明了在 WRRF 中选择适当的生物固体处理策略和能源回收实践的经济和环境相关性。
