Constructed wetlands (CWs) offer effective, economical, environment-friendly and energy-efficient solution to growing challenges of increasing sewage and wastewater loads in urban areas. Although microbial communities form an integral component of constructed wetlands for sewage treatment, functional processes and their dynamics during sewage bioremediation in constructed wetlands remain largely uncharacterized. Moreover, the association of specific bacterial taxa with remediation of different sewage and water quality parameters remains largely unclear. This study explored the functional diversity likely associated with microbial communities of a constructed wetland system used for in situ remediation of 1 MLD (Million Liters per Day) sewage without external energy input since 2014. Different bacterial functional groups in the sludge from a stabilization pond and from rhizospheric sediments of the integrated constructed wetland were predicted using a 16S rRNA gene metagenomic sequencing dataset. Correlation analysis, multivariate statistics and a co-occurrence network were used to assess the bacterial groups associated with changes in water quality as it flows through different components of the integrated CW and highlight association patterns predicting major exchanges which might be operating in the microbial communities. While stabilization pond microbiome was dominated by bacterial groups such as Firmicutes, Desulfobacterota and Methylomirabilota known to be involved in carbon fermentation, sulphate reduction and methanogenesis, the rhizospheric sediments showed prevalence of bacteria associated with nitrogen reduction including Nitrospirota and Planctomycetota contributing to improved sewage quality parameters. Such results indicated complex microbial interactions involving bacteria from diverse functional groups sustaining bioremediation in the CW. The identification of primary bacterial taxa along with their putative functions can help in designing strategies to improve sustainable, nature-based wastewater treatment by CW systems.
Seth et al. (Thu,) studied this question.