排水管道甲烷产生影响因素及其估算方法

Affecting Factors and Estimating Methods of Methane Produced in Sewers

排水管道甲烷(CH_(4))释放属于“自然”现象,是一种容易被忽视的隐形碳排源。污水中的有机物(COD)、排水管道的厌氧环境为产甲烷细菌(MA)的滋生创造了必要条件,导致非控条件下排水管道中会不可避免地产生CH_(4)。定量估算排水管道CH_(4)生成量既有简单系数估算法,也有模型预测方式,无论哪种估算方法,我国排水管道CH_(4)年排放量都在2000×10^(4) tCO_(2)-eq/a左右,其值已经接近我国污水处理厂碳排总量(3985×10^(4) tCO_(2)-eq/a)的1/2。因此,排水管道CH_(4)排放量不可小觑。从技术角度,可通过人工干预方式对CH_(4)的生成与释放进行控制,如源头抑制(投加高铁酸盐、游离氨、亚硝酸,调节pH)、过程控制(管道设计和运营管理)、末端处理(尾气处理)等方式。

Methane(CH_(4))released from sewers is a natural phenomenon,which is an invisible carbon emission source that is easily neglected.Chemical oxygen demand(COD)in wastewater and the anaerobic environment in sewers favor the growth of methanogenic archaea(MA),and will lead to the inevitable CH_(4) production.Simple coefficient estimation and model prediction are methods for quantitative estimation of CH_(4) production in sewers.The CH_(4) emission from sewers in China is around 20 million tCO_(2)-eq/a taking these estimation methods,which is nearly half of the total carbon emissions from wastewater treatment plants(39.85 million tCO_(2)-eq/a)in China.Under the circumstance,CH_(4) released from sewers should not be underestimated and neglected.The technical measures for controlling CH_(4) generation and release in sewers include source control(adding ferrate,free ammonia and nitrous as well as controlling pH),process management(pipeline design and operation),end-of-pipe treatment(off-gas treatment),etc.