State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Sci Total Environ. 2023 Jan 10;855:158629. doi: 10.1016/j.scitotenv.2022.158629. Epub 2022 Sep 7.
Sewage treatment provides a pathway for anthropogenic water purification that can address the growth in domestic sewage volumes due to urbanization and protect the aquatic environment. However, the process can also generate greenhouse gases (GHGs), which are sometimes termed "unrestricted" GHG emissions and are neglected by low carbon policies. A combination of a life cycle analysis (LCA), data envelopment analysis (DEA), and questionnaire survey was used to evaluate sewage treatment related GHG emissions and assess the GHG emission reduction efficiencies during 2005-2020, as well as determine the opinions of environmental managers regarding the threats to climate change mitigation posed by sewage treatment in the low carbon pilot city of Shenzhen, China. There were four main results. (1) GHG emissions from sewage treatment plants (STPs) in Shenzhen increased gradually from 0.22 Mt. CO-eq in 2005 to 1.16 Mt. CO-eq in 2020 with an emission intensity ranging from 0.41 to 0.58 kg CO-eq/m, mainly due to the indirect emissions from sludge disposal (35-57 %). Longgang administrative district was the hotspot of these GHG emissions during the study period. (2) Reductions in GHG emissions were achieved in most years since 2012 with the greatest efficiency observed in 2020. (3) Beyond the environmental managers' perceptions of the challenges in GHG mitigation, future sewage treatment may create the potential for more substantial GHG emission growth compared to the emissions from energy combustion, due to policy deficiencies, growth in sewage volumes, and the enforcement of stricter effluent quality control. (4) Several opportunities to overcome these barriers were considered including innovational environmental management, planting of constructed wetlands, and the promotion of water-saving behavior. This case study of Shenzhen has valuable implications for the synergistic governance of water pollution and climate change mitigation in megacities in China and elsewhere, enabling a move towards a future carbon-neutral society.
污水处理提供了一种人为净化水的途径，可以解决城市化导致的生活污水量增加问题，并保护水生态环境。然而，该过程也会产生温室气体（GHG），这些温室气体有时被称为“无限制”温室气体排放，并且被低碳政策所忽视。本研究采用生命周期分析（LCA）、数据包络分析（DEA）和问卷调查相结合的方法，评估了污水处理相关的温室气体排放，并评估了 2005-2020 年期间的温室气体减排效率，同时确定了深圳市（中国低碳试点城市）环境管理者对污水处理减轻气候变化威胁的看法。主要有四个结果。（1）深圳市污水处理厂（STP）的温室气体排放量从 2005 年的 0.22 Mt.CO-eq 逐渐增加到 2020 年的 1.16 Mt.CO-eq，排放强度在 0.41-0.58 kg.CO-eq/m 之间，主要是由于污泥处置产生的间接排放（35-57%）。在研究期间，龙岗行政区是这些温室气体排放的热点地区。（2）自 2012 年以来，大多数年份的温室气体排放量都有所减少，2020 年的减排效率最高。（3）除了环境管理者对温室气体减排挑战的看法外，由于政策缺陷、污水量增长以及更严格的出水质量控制的实施，未来污水处理可能会产生比能源燃烧更大的温室气体排放增长潜力。（4）考虑了克服这些障碍的几种机会，包括创新的环境管理、人工湿地的种植以及节约用水行为的推广。本案例研究对中国乃至其他大城市水污染和气候变化协同治理具有重要意义，为向未来的碳中和社会迈进奠定了基础。
