Citation:

Li, L., D. Ning, Y. Jeon, H. Ryu, J. SantoDomingo, D. Kang, A. Kadudula, AND Y. Seo. Ecological Insights into Assembly Processes and Network Structures of Bacterial Biofilms in Full-scale Biologically Active Carbon Filters under Ozone Implementation. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, Netherlands, 751:141409, (2021). https://doi.org/10.1016/j.scitotenv.2020.141409

Impact/Purpose:

The increasing occurrence and severity of cyanobacterial harmful algal blooms (HABs) in freshwater have challenged the quality and safety of drinking water supplies. Conventional treatment processes, comprised of coagulation, sedimentation, and granular media filtration, are known to be ineffective in completely removing algal organic matter including taste/odor-causing compounds and cyanotoxins. Notably, various kinds of cyanotoxins detected in the finished water have raised great concerns over public health protection. To address this emerging issue and provide a reliable treatment barrier for cyanobacteria-impacted source water, many water utilities are examining innovative approaches and/or upgrading their existing drinking water treatment plants (DWTPs). The advanced oxidation process of ozonation followed by biologically active carbon (BAC) filtration has recently attracted much attention, especially in upgrading water treatment plants, as it can remove a wide range of natural organic matter (NOM), while simultaneously reducing micropollutants and minimizing the formation of disinfection byproducts. Given the fact that BAC filters are vital components and significantly affect finished water quality and other downstream processes in DWTPs, integrating sequencing results and microbial ecology theory should provide new insights for comprehensively managing and optimizing BAC filter performance. Accordingly, a quantitative ecological null model was applied to unravel the driving forces that regulate the bacterial biofilm assemblage in full-scale BAC filters, which underwent a new ozone system installation. Ecological network analysis was also conducted to examine the topological properties of bacterial networks and potential interspecies interactions (important elements in deterministic processes). Additionally, the 16S rRNA gene sequencing data was used to predict the corresponding changes of bacterial functions in BAC filters.

Description:

To address the adverse effects of harmful algal blooms, there are increased demands over the implementation of ozone-biologically active carbon (BAC) filters in the drinking water treatment plants. Although the microbial biofilms are vital elements to support the proper performance of BAC filters, except for taxonomic affiliations, little is known about the temporal dynamics of bacterial communities in the full-scale BAC filters. In this study, we investigated the temporal dynamics of bacterial assembly mechanisms, phylogenetic molecular network structures, and their functional potential in full-scale BAC filters which underwent ozone implementation (across five seasons). Along with the increase of bacterial taxonomic richness and evenness, the ecological null model revealed that stochastic processes became more crucial to determine the bacterial community assembly in the summer and autumn after ozone implementation. Moreover, their corresponding networks possessed simple network structures with lower modularity than other seasons, which implied less intense interactions among bacterial populations. Additionally, the correlations between taxonomic and predicted functional diversities suggested that relatively high levels of bacterial functional redundancy generally exist in BAC filters. The functional redundancy indices further demonstrated that higher degrees of functional redundancy existed in the summer and autumn after ozone implementation than the other three seasons. Overall, this work established a potential ecological framework to characterize the bacterial communities in BAC filters and provide novel insights into formulating operational strategies to optimize the performance of full-scale BAC filters.

URLs/Downloads:

Record Details: