Biochar Affects Microbial Attachment and Biofilm Formation Besides Improving Pollutant Removal and Changing Microbial Community in Constructed Wetlands
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Titel:
Biochar Affects Microbial Attachment and Biofilm Formation Besides Improving Pollutant Removal and Changing Microbial Community in Constructed Wetlands
Beschreibung:
As the regulator of constructed wetlands (CWs), biochar is often used to enhance pollutant removal and reduce greenhouse gas emission. Biochar is proved to have certain effects on microbial populations, but its effect on the aggregation of microbial flocs and the formation of biofilms in CWs has not been thoroughly investigated. Therefore, the above topics were studied in this paper by adding a certain proportion of biochar in aerated subsurface flow constructed wetlands. The results indicated that after adding biochar in CWs, pollutant removal was enhanced, especially for nitrogen pollutants, and the weakened hydrophobic and the reduced affinity of extracellular polymeric substances (EPS) inhibited the initial attachment of microorganisms. The relative abundance of Chloroflexi was decreased after adding biochar, reducing the dense structural skeleton of biofilm aggregates. Correspondingly, the abundance of Bacteroidetes was increased, promoting EPS degradation. Biochar addition increased the proportion of catalytic active proteins in extracellular proteins, but decreased the proportion of binding active proteins, hindering the combination of extracellular proteins and macromolecules to form microbial aggregates. Additionally, the proportions of three extracellular protein structures promoting microbial aggregation, including aggregated chain, β-sheet, and 3-turn helix, were decreased, while random coil and antiparallel β-sheet inhibiting microbial aggregation were increased. An interesting conclusion from the experimental results is that biochar not only can enhance pollutants removal, but also has the potential of alleviating biological clogging in CWs, which is of great significance to realize the sustainable operation and improve the life cycle of CWs