基于碳足迹核算的农村生活污水处理工艺比选

Comparison and selection of rural domestic sewage treatment processes based on carbon footprint accounting

  • 摘要: 农村生活污水处理作为污水处理行业的重要组成部分之一,其工艺选择与运行管理具有较大的减排潜力,然而针对农村生活污水处理工艺的碳足迹核算鲜有研究。编制了农村生活污水处理基于全生命周期评价(LCA)的排放清单,并据其对长三角地区4种典型农村生活污水处理工艺进行了碳足迹核算。结果表明:在进出水水质类似、处理效果相当情况下,一体化厌氧-好氧(AO)工艺的碳足迹为1.635 kg/m3(以CO2当量计,全文同),膜生物反应器(MBR)工艺的碳足迹为2.140 kg/m3,生物滤池(BAF)+人工湿地(CW)工艺的碳足迹为0.814 kg/m3,自流增氧(OT)+CW工艺的碳足迹为1.060 kg/m3;碳足迹影响因素按影响程度从高到低分别为电力消耗(45.70%~64.61%)、温室气体直接排放(20.02%~29.73%)、药物/物料消耗(6.93%~16.70%)、污泥处理处置(5.53%~9.99%)和尾水排放(2.01%~5.98%);在“双碳”背景下,BAF+CW是相对理想的农村生活污水处理工艺,并且比碳排放和敏感性结果显示,减少电能消耗是降低碳足迹的首要途径。本研究可为“双碳”背景下农村生活污水处理工艺的筛选提供借鉴。

     

    Abstract: As a vital part of the wastewater treatment industry, rural domestic wastewater treatment holds substantial potential for emission reduction. However, there has been little research on carbon footprint accounting in rural domestic wastewater treatment processes. Therefore, accounting for the carbon footprint of these processes is crucial. An emission inventory based on life cycle assessment (LCA) was compiled, and carbon footprint accounting for four typical rural domestic wastewater treatment technologies was conducted based on this inventory. The results indicated that the carbon footprint of the Anaerobic-oxic process (AO) was 1.635 kg/m³ (in terms of CO2-eq, applies throughout the text), the membrane bio-reactor process (MBR) was 2.140 kg/m³, the biological aerated filter (BAF) + constructed wetland (CW) process was 0.814 kg/m³, and the Oxygenating tank (OT) + CW process was 1.060 kg/m³. The factors influencing the carbon footprint ranked by impact were electricity consumption (45.70%-64.61%), direct greenhouse gas emissions (20.02%-29.73%), chemical/material consumption (6.93%-16.70%), sludge treatment and disposal (5.53%-9.99%), and effluent discharge (2.01%-5.98%). Under the "dual carbon" strategy, BAF+CW process emerged as a relatively ideal rural domestic wastewater treatment process. The results of carbon emissions per unit of pollutant and sensitivity analysis showed that reducing electricity consumption was identified as the primary approach to lowering the carbon footprint. This study could provide a theoretical basis for selecting rural domestic wastewater treatment processes under the "dual carbon" strategy.

     

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