Roles of granular activated carbon (GAC) and operational factors on active microbiome development in anaerobic reactors

Ambient temperature municipal sewage was treated using two laboratory-scale up-flow anaerobic sludge blanket reactors for 225 days. Granular activated carbon (GAC) was added to one reactor to facilitate the development of direct interspecies electron transfer (DIET). The GAC addition increased total chemical oxygen demand removal by 5% - 18%. In addition to assessing the relative abundance of active amplicon sequence variants (ASVs), the mass balance model, the Mantel test, and the generalized linear models were applied to evaluate the dynamics of the active ASVs and the key operational factors controlling the bioreactor microbial community. These results demonstrated that, in addition to the GAC addition, extrinsic engineering operational factors played important roles in controlling (active) microbial communities. This study underlines the importance of taking a wholistic approach to assess microbial population dynamics. Reactor design and performance prediction should consider key engineering parameters when using DIET-based AD reactors in the future.

Automated summary

The study found that adding granular activated carbon to the reactor can increase the total chemical oxygen demand removal rate when treating municipal sewage at ambient temperature. In addition to GAC addition, external engineering operational factors also play an important role in controlling microbial communities. When designing and using DIET-based AD reactors in the future, key engineering parameters should be considered comprehensively.