重庆市城镇生活污水碳排放时空分布特征

Temporal and Spatial Distribution Characteristics of Carbon Emissions from Urban Domestic Sewage in Chongqing

化粪池中因发生生活污水生化消解反应而产生的碳排放问题应予以重视。为此,提出生活污水“首次”生化消解反应的概念,并选择重庆市这一西部重镇作为研究区域,通过3389台气体传感设备,采用Fick扩散定律测算出2019年—2021年的“首次”碳排放量,得出重庆市主城区居民生活污水“首次”生化消解反应碳排放的时空分布特征。结果表明,2019年—2021年生活污水碳排放量(以二氧化碳当量计)分别约为4.443×10~8、4.554×10~8和2.730×10~8 kg,其中各区县均有超过99%的甲烷会从化粪池逸散到外部空间;实现化粪池的取缔工作与城市碳减排工作的有机结合、新建污水处理厂,充分挖掘城镇生活污水及其生化消解反应产生的甲烷气体的各种价值必然是大势所趋,为未来逐步取消化粪池提供了新思路和新动力;2019年—2021年生活污水“首次”生化消解反应的高碳排放区域均分布在主城区西部、南部以及主城区中心地带,低碳排放区域减少,中碳排放区域增加,碳排放空间分布差异减小;气候对生活污水“首次”生化消解反应碳排放有显著影响,2019年—2021年,碳排放随冬、春、夏、秋的四季变化呈现出“高-低-高-低”的分布态势。

The carbon emissions resulting from the biochemical digestion of domestic sewage in septic tanks require greater attention.The concept of the“first”biochemical digestion of domestic sewage was introduced,with Chongqing City,a key town in western China,selected as the research area.By utilizing 3389 gas sensing devices,Fick’s diffusion law was employed to calculate the“first”carbon emissions from 2019 to 2021.This study obtained the temporal and spatial distribution characteristics of carbon emissions from the“first”biochemical digestion of domestic sewage in the main urban area of Chongqing.The carbon emissions of domestic sewage(in terms of carbon dioxide equivalent)from 2019 to2021 were approximately 4.443×10~8 kg,4.554×10~8 kg and 2.730×10~8 kg,respectively.It was worth noting that more than 99%of the methane in each district and county escaped into the external space.The organic combination of the prohibition of septic tanks and urban carbon emission reduction work,and the construction of sewage treatment plants necessitated the full exploitation of various values of urban domestic sewage and methane generated by biochemical digestion.These measures represented inevitable trends,providing new ideas and impetus for the gradual elimination of septic tanks in future.From 2019 to 2021,the high-carbon emission areas of the“first”biochemical digestion of domestic sewage were predominantly located in the western and southern regions of the main urban area,as well as in the central area.Conversely,there was a decrease in low carbon emission areas,an increase in medium carbon emission areas,and a reduction in spatial distribution disparity of carbon emissions.The climate exerted a significant influence on the carbon emissions resulting from the“first”biochemical digestion of domestic sewage.Over the period from 2019 to 2021,there was an observable fluctuation in carbon emissions,following a pattern of high-low-high-low distribution corresponding to the four seasons of winter,spring,summer,and autumn.