Methanogenic Potential\nof Sewer Microbiomes and Its\nImplications for Methane Emission

The sewer system, despite being a significant source\nof methane\nemissions, has often been overlooked in current greenhouse gas inventories\ndue to the limited availability of quantitative data. Direct monitoring\nin sewers can be expensive or biased due to access limitations and\ninternal heterogeneity of sewer networks. Fortunately, since methane\nis almost exclusively biogenic in sewers, we demonstrate in this study\nthat the methanogenic potential can be estimated using known sewer\nmicrobiome data. By combining data mining techniques and bioinformatics\ndatabases, we developed the first data-driven method to analyze methanogenic\npotentials using a data set containing 633 observations of 53 variables\nobtained from literature mining. The methanogenic potential in the\nsewer sediment was around 250–870% higher than that in the\nwet biofilm on the pipe and sewage water. Additionally, <i>k</i>-means clustering and principal component analysis linked higher\nmethane emission rates (9.72 ± 51.3 kg<sub>CO<sub>2</sub> eq</sub> m<sup>–3</sup> d<sup>–1</sup>) with smaller pipe size,\nhigher water level, and higher potentials of sulfate reduction in\nthe wetted pipe biofilm. These findings exhibit the possibility of\nconnecting microbiome data with biogenic greenhouse gases, further\noffering insights into new approaches for understanding greenhouse\ngas emissions from understudied sources.