Abstract
Microbial community composition and stability affect pollutant removal for biological/granular activated carbon (BAC/GAC) processes. Here, we pre-loaded the organic carbon substrates sucrose, lactose, and Lysogeny Broth (LB) medium onto new GAC prior to use and then tested whether this substrate pre-loading promoted development of biofilms with high coverage that remained stable for prolonged operational periods. Temporal dynamics of the biomass and microbial community on the GAC were monitored via flow cytometry (FCM) and sequencing, respectively, in both batch and continuous-flow experiments. In comparison with the non-loaded GAC (control), the initial biofilm biomass on substrate-loaded GAC was 3–114 times higher, but the initial richness was considerably lower (only accounting for 13–28% of the control). The initial community compositions were significantly different between batch and continuous-flow column experiments, even when loaded with the same substrates. In the continuous-flow column experiments, both biomass and microbial community composition became remarkably similar to the control filters after 64 days of operation. From these findings, we conclude that substrate-loaded GAC could enhance initial colonization, affecting both biomass and microbial community composition. However, the biomass and composition did not remain stable during long-term operation due to continuous dispersal and competition from influent bacteria.
Highlights
Biological/granular activated carbon (BAC/GAC) filtration, which combines adsorption with biodegradation, is a promising method for the removal of organics, is general, and removes micro-pollutants from drinking water and wastewater (Kirisits et al, 2001; Kalkan et al, 2011; Chu et al, 2012; Jantarakasem et al, 2020; Zhiteneva et al, 2020)
Glucose, sucrose, lactose, and Lysogeny Broth (LB) medium were initially selected as the primary carbon substrates
Sucrose, lactose, and LB medium were selected as carbon substrates in the subsequent experiments in this study
Summary
Biological/granular activated carbon (BAC/GAC) filtration, which combines adsorption with biodegradation, is a promising method for the removal of organics, is general, and removes micro-pollutants from drinking water and wastewater (Kirisits et al, 2001; Kalkan et al, 2011; Chu et al, 2012; Jantarakasem et al, 2020; Zhiteneva et al, 2020). New biofilters typically require a long start-up period (2–3 months) to reach a steady state in biofilm concentration, community composition, and targeted pollutant effluent concentration (Velten et al, 2011; Han et al, 2013; Zheng et al, 2018). It is Manipulation of GAC Biofilter Biofilms conceivable that targeted pollutants could not be removed efficiently due to failed/insufficient colonization of the specific species required for their degradation. Targeted initial GAC colonization, enrichment of specific communities, and maintenance of the stability of these enriched bacteria on GAC filters are essential to shorten the start-up time and to enhance removal efficiency of targeted pollutants
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