Functional diversity of the microbiome of an activated carbon filter for wastewater treatment: perspective of bioaugmentation for micropollutant degradation

Traditional wastewater treatment methods are ineffective at removing micropollutants like pesticides, pharmaceuticals, microplastics, and nanoparticles. Advanced techniques such as activated carbon filters (ACFs) improve the elimination of trace chemicals. There is limited research on the microbiome and associated processes in ACFs despite the cognition that microbial biodegradation takes place in these filters.

Our research aims to understand the microbial communities and their functional role of specific bacterial microbiomes within ACFs with the perspective of bioaugmentation by introducing micropollutant-degrading bacteria. To achieve this, microbiome analysis via amplicon sequencing and physiological experiments were employed.

The initial analysis of the microbiome of a newly installed ACF at a wastewater treatment plant revealed a diverse range of bacterial groups colonizing the AC over 12 months. Pairwise PERMANOVA tests indicated that the bacterial communities differed significantly (Padonis< 0.05) between sampling points. Sphingomonadaceae, Chitinophagaceae, Hyphomonadaceae, Nitrosomonadaceae, and Comamonadaceae consistently dominated the samples. Based on the molecular data, members of the Chitinophagaceae are expected to be involved in the breakdown of polysaccharides within the ACF biofilm. The concurrent presence of Nitrosomonadaceae, Hyphomonadaceae, and Comamonadaceae with known nitrifying and denitrifying members indicates that nitrogen elimination might take place within the ACF. Additionally, Sphingomonadaceae and Comamonadaceae might be involved in the biodegradation of organic micropollutants in the AC filter.

Physiological experiments with Novosphingobium and Pseudomonas strains indicated that N. aromaticivorans can actively desorb adsorbed organic compounds from AC while P. putida was unable. This notion aligned with molecular data indicating the absence of pseudomonads in the ACF.

These findings provide insight into the functional capabilities of specific bacterial groups within ACFs and suggest the potential of using Sphingomonadaceae for bioaugmentation to enhance micropollutant degradation in wastewater treatment processes.