在当前全球气候变化的大背景下,城镇生活污水处理厂作为城镇供排水系统的组成部分,是重要的温室气体排放源之一.基于排放因子法,对中国东南沿海某省会城市4座不同工艺的生活污水处理厂进行了碳排放核算,分析了不同工艺之间的碳排放特征和强度的差异.研究对象包括采用卡鲁塞尔氧化沟(OD)、厌氧-缺氧-好氧(A2/O)、厌氧-缺氧-好氧与膜生物反应器结合(A2/O+MBR)以及循环式活性污泥法(CASS)工艺的污水处理厂.结果表明,4座污水处理厂的碳排放总量和结构存在显著差异.A2/O+MBR工艺因其高能耗和药剂使用导致碳排放强度最高,平均为0.403 kg CO2-eq/m3;CASS工艺由于其周期性运行模式,N2O排放占比显著,但其电力和药剂消耗有明显优势.OD和A2/O工艺运行稳定,碳排放强度波动较小.研究发现,处理水量和进水TN浓度是影响碳排放强度的关键因素,其中,A2/O+MBR工艺表现出显著的规模效应.基于上述分析,提出了南方地区污水处理厂的碳削减对策,包括低碳规划、工艺选择、运行优化和因子本地化等方面.通过这些策略,可以有效减少污水处理过程中的碳排放,推动污水处理向低碳高效方向发展.
CARBON EMISSIONS CHARACTERISTICS AND REDUCTION STRATEGIES FOR TYPICAL URBAN DOMESTIC WASTEWATER TREATMENT PLANTS IN SOUTHEASTERN CHINA
In the context of global climate change,urban domestic wastewater treatment plants,as a crucial component of urban water supply and drainage systems,are complex sources of greenhouse gas emissions.This study,based on the emission factor method,conducted a carbon emission accounting for four domestic wastewater treatment plants using different processes in a provincial capital city in southeastern China.Those processes include the Carrousel oxidation ditch(OD),anaerobic-anoxic-oxic(A2/O),anaerobic-anoxic-oxic combined with membrane bioreactor(A2/O+MBR),and cyclic activated sludge system(CASS).The results indicated significant differences in the total and structural carbon emissions among the four treatment plants.The A2/O+MBR process exhibits the highest carbon emission intensity,averaging 0.403 kg CO2-eq/m3,due to its high energy consumption and chemical usage.The CASS process,with its cyclic operation mode,shows a significant proportion of N2O emissions but has obvious advantages in terms of electricity and chemical consumption.The OD and A2/O process operate stably with relatively lower fluctuations in carbon emission intensity.The study also found that treatment water volume and influent TN concentration are key factors influencing carbon emission intensity,with the A2/O+MBR process demonstrating a significant scale effect.Based on the analysis,this paper proposed carbon reduction strategies for wastewater treatment plants in southeastern China,including optimizing process selection,addressing key influencing factors,proactively responding to low water quality issues,and establishing localized emission factors.Implementing these strategies can effectively reduce carbon emissions in the wastewater treatment process and promote the development of low-carbon and efficient wastewater treatment.
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