Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong S.A.R.
Department of Civil and Environmental Engineering, Imperial College London, South Kensington SW7 2AZ, London, United Kingdom.
Environ Sci Technol. 2020 Apr 21;54(8):4746-4757. doi: 10.1021/acs.est.9b05755. Epub 2020 Mar 30.
Several life-cycle assessments (LCAs) have evaluated the environmental impacts (EIs) of different wastewater treatment (WWT) configurations, attempting resource recovery and energy efficiency. However, a plant-wide LCA considering up-concentration primary treatment and low carbon-to-nitrogen (C/N) ratio sewage at the secondary biological treatment (SBT) has not yet been conducted. This study identifies the environmental trade-offs and hotspots for the chemically enhanced primary treatment (CEPT) and low C/N ratio SBT emerging processes compared to conventional WWT. The life-cycle inventories were calculated using a stoichiometric life-cycle inventory framework that couples stoichiometry and kinetics to obtain site-specific water, air, and soil emissions. The midpoint results of LCA show that CEPT with anaerobic digestion (AD) for sludge treatment achieves energy self-sufficiency, but increases marine eutrophication (MEu) by 1 order of magnitude compared to conventional WWT. A mainstream anaerobic fluidized-bed bioreactor and a partial nitritation-anammox fluidized-bed membrane bioreactor which can reduce all environmental impacts by 17-47%, including MEu, are proposed as the SBT of the low-carbon CEPT settled sewage. Integrating the standardized S-LCI framework resulted in a site-specific LCA that aids decision-makers on choosing between higher reductions in most EIs at the expense of high MEu or less but consistent reductions in all EI categories.
已有几项生命周期评估（LCA）针对不同的废水处理（WWT）配置评估了环境影响（EI），同时尝试资源回收和提高能源效率。然而，对于在二级生物处理（SBT）中采用上向流一级处理和低碳氮比（C/N）污水的全厂范围的 LCA 还尚未进行。本研究确定了与传统 WWT 相比，强化一级处理（CEPT）和低碳氮比 SBT 新兴工艺的环境权衡和热点。使用化学计量生命周期清单框架计算了生命周期清单，该框架将化学计量学和动力学结合起来，以获得特定地点的水、空气和土壤排放。LCA 的中点结果表明，与传统 WWT 相比，采用厌氧消化（AD）处理污泥的 CEPT 可实现能源自给自足，但会使海洋富营养化（MEu）增加 1 个数量级。提出采用主流厌氧流化床生物反应器和部分硝化-厌氧氨氧化流化床膜生物反应器作为低碳 CEPT 沉淀污水的 SBT，可将所有环境影响（包括 MEu）降低 17-47%。整合标准化 S-LCI 框架可进行特定地点的 LCA，帮助决策者在以 MEu 升高为代价换取大多数 EI 大幅降低，或在所有 EI 类别中降低幅度较小但一致之间做出选择。
