Effects of Granular Activated Carbon Amendment, Temperature, and Organic Loading Rate on Microbial Communities in Up-Flow Anaerobic Sludge Blanket Reactors

Abstract

Methane recovery in up-flow anaerobic sludge blanket (UASB) reactors performing anaerobic digestion (AD) can be improved with adjustments in operational factors such as temperature, organic loading rate, and the addition of granular activated carbon (GAC). This study aims to perform a multiple operational factor analysis for their impacts on UASB microbial communities. Data collected from seven continuously operated UASB reactors and batch tests were analyzed using a range of bioinformatics and statistical tools. Temperature and reactor types were the most important factors in microbial communities in UASB reactors, although the addition of GAC also had a statically significant impact. The positive and negative correlations between classified phylotypes and performance indicators were determined. It was noted that more phylotypes were positively correlated with hydrogenotrophic specific methanogenic activity (SMA) than acetoclastic SMA. The occurrence network of the overall microbial communities from samples amended with GAC was modularized into eight main groups (occupying 92% of the nodes). Seven modules containing both methanogens and syntrophs were identified as potential functional communities for AD. These modules were mainly regulated by reactor types and driven by different combinations of operational factors using co-occurrence network analysis and generalized joint attribute modeling. Overall, the paper bridged operational configurations and reactor performance with microbial community dynamics.