Conventional processes for municipal wastewater treatment facilities are energy and materially intensive. This work quantifies the air emission implications of energy consumption, chemical use, and direct pollutant release at municipal wastewater treatment facilities across the U.S. and assesses the potential to avoid these damages by generating electricity and heat from the combustion of biogas produced during anaerobic sludge digestion. We find that embedded and on-site air emissions from municipal wastewater treatment imposed human health, environmental, and climate (HEC) damages on the order of $1.63 billion USD in 2012, with 85% of these damages attributed to the estimated consumption of 19 500 GWh of electricity by treatment processes annually, or 0.53% of the US electricity demand. An additional 11.8 million tons of biogenic CO₂ are directly emitted by wastewater treatment and sludge digestion processes currently installed at plants. Retrofitting existing wastewater treatment facilities with anaerobic sludge digestion for biogas production and biogas-fueled heat and electricity generation has the potential to reduce HEC damages by up to 24.9% relative to baseline emissions. Retrofitting only large plants (>5 MGD), where biogas generation is more likely to be economically viable, would generate HEC benefits of $254 annually. These findings reinforce the importance of accounting for use-phase embedded air emissions and spatially resolved marginal damage estimates when designing sustainable infrastructure systems.

中文翻译：

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市政污水处理厂减少沼气发电的废气排放效益

用于市政废水处理设施的常规过程是能源和材料密集型的。这项工作量化了能源消耗，化学药品使用以及美国全市市政污水处理设施中污染物的直接排放对空气排放的影响，并评估了通过厌氧污泥消化过程中产生的沼气燃烧产生的电能和热量来避免这些损害的潜力。我们发现，市政废水处理产生的嵌入式和现场排放的空气在2012年对人类健康，环境和气候（HEC）造成了约16.3亿美元的损失，其中85％的损失归因于19500的估计消耗量每年通过处理过程产生的电力GWh，占美国电力需求的0.53％。额外的1180万吨生物CO目前工厂中安装的废水处理和污泥消化过程直接排放出₂种。用厌氧污泥消化法改造现有的废水处理设施，以生产沼气，以沼气为燃料的热力和电力，相对于基准排放量，有可能将HEC损害减少多达24.9％。仅对大型工厂（> 5 MGD）进行改造，在这种情况下，沼气的生产更有可能在经济上可行，每年将产生254美元的HEC收益。这些发现加强了在设计可持续基础设施系统时考虑使用阶段嵌入式空气排放和空间分辨的边际损害估计的重要性。