下水道甲烷释放模型评价与内在控制分析

Evaluating Methane Emission Models of Sewers and Analyzing Inherent Control

下水道产生的甲烷排放量近似污水处理过程能耗产生的间接碳排放量,其温室效应不可小觑。通过对下水道甲烷产生与释放过程模型总结、归纳,厘清了下水道甲烷排放模型差异及其适用范围。采用正交试验方法,特别对预测模型中主要控制因子影响甲烷生成量程度进行了显著性分析。计算结果显示,温度对甲烷产生量的影响程度最为显著;进行管道在线热量交换而降温技术上虽然可行但并不可取,因为这势必影响冬季污水生物处理效果。污水COD浓度与管道管径影响程度次之,但受客观条件制约也显得束手无策。归根结底,唯有减少污水管道中流动时间方有可能避免甲烷形成,对此可采用负压排水系统作为技术解决方案,但需核算能耗间接碳排放(CO_(2))与管道CH_(4)排放间的差异。投加化学药剂等外源介入措施固然可一定程度抑制产甲烷细菌活性,但必须考虑维护费用与间接碳排放等问题。

Methane emission from sewers is almost close to indirect carbon emission from energy consumption of wastewater treatment,so that its greenhouse effect should not be underestimated.Some models describing methane production and emission in sewers are first analyzed and summarized,which clarifies the differences and application scopes of these models.Based on the orthogonal tests,the significant degree of key factors on affecting methane production is fully analyzed for the predicting models.The calculated results reveal that temperature has the most significant influence on methane production;lowering temperature by exchanging heat online is feasible but not desirable as this action would inevitably affect biological wastewater treatment during the winter time.The COD concentration and sewers’diameter are the second to affecting methane production,but it seems as if hands be tied because of objective conditions.On balance,reducing the flowing time of wastewater in sewers might be the only approach to avoiding methane production.In this aspect,vacuum sewer system(VSS)seems a technical solution,but it is essential to balance the indirect CO2 emission of energy consumption caused by VSS and direct CH4 emission from sewers.Besides,such external intervention measures as adding chemicals into sewers could inhibit the activity of methanogens to an extent,but maintenance costs and indirect carbon emissions have to be considered.