Propane biostimulation in biologically activated carbon (BAC) selects for bacterial clades adept at degrading persistent water pollutants

Abstract

Biologically activated carbon (BAC) can be used in both municipal water and hazardous waste remediation applications to enhance contaminant attenuation in water; however, questions remain about how selective pressures can be applied to increase the capabilities of microbial communities to attenuate recalcitrant contaminants. Here we utilized flow-through laboratory columns seeded with municipally derived BAC and exposed to water from a local drinking water facility to query how propane biostimulation impacts resident microorganisms. Ecological analyses using high throughput phylogenetic sequencing revealed that while propane did not increase the total number of microbiological species, it did select for bacterial communities that were distinct from those without propane. Temporal extractions demonstrated that microbial succession was rapid and established in approximately 2 months. A higher density of propane monooxygenase genes and bacterial clades including the Pelosinus and Dechloromonas genera suggest an enhanced potential for the degradation of persistent water pollutants in propane-stimulated systems. However, the ecological selective pressure was exhausted in less than 15 cm of transit in this flow-through scenario (25 hour retention) indicating a pronounced zonation that could limit the size of a biostimulated zone and require physical mixing, hydraulic manipulation, or other strategies to increase the spatial impact of biostimulation in flow-through scenarios.

Effect of advanced oxidation on N-nitrosodimethylamine (NDMA) formation and microbial ecology during pilot-scale biological activated carbon filtration

“…Interestingly, the highest population diversities were in the top samples ( Fig S2) where a significant decrease with depth was found in both columns (Kruskal-Wallis H Test, both P< 0.001). Similar phenomena were observed in a previous pilot-scale up-flow BAC filtration system treating lake water with pre-ozonation, in which a marked decrease of microbial diversity in the BAC filtration system was observed along the flow path (Liao et al, 2012) and a lab scale BAC filtration system (Mikkelson et al, 2015). In contrast, a converse trend with increasing diversity during biofiltration transit has been observed in sand sediment columns exposed to surface and wastewaters (Li et al, 2012 and.…”

“…This phylogenic profile is consistent with nitrate formation during BAC transit as described in the prior section. Analogously, Nitrospira were found in the top layers (0.3 m below the surface) of two BAC columns that received ozone treated water (accounting for 3.4% and 5.3% of total microbial population) in a previous study (Liao et al, 2013b) and were dominant (5.1% of total microbial population) in the top layer of a BAC column receiving tap water (Mikkelson et al, 2015). Planctomyces species belong to the phylum Planctomycetes, which hosts guilds capable of anammox metabolism (Kartal et al, 2013), were abundant in the top samples of both columns (3.4% and 1.0%, respectively), suggesting a potential interplay with Nitrospira.…”

“…A more intimate knowledge of microbial phylogenetic composition and selective biases in these systems could enhance functional understanding of BAC treatment perhaps informing the selection of desirable candidate populations, design and management practices. While studies have begun to explore the effects of upstream water properties on the phylogenetic structure of microbial populations in BAC systems (Mikkelson et al, 2015), the effects of AOPs remain largely unknown and appear limited to BAC systems following ozonation (Kasuga et al, 2007;Liao et al, 2012Liao et al, , 2013aLiao et al, and 2013b. Ozone and UV/H 2 O 2 both utilize hydroxyl radicals to break/alter chemical structures of parent organic compounds including persistent pollutants.…”

Impact of algal organic matter on the performance, cyanotoxin removal, and biofilms of biologically-active filtration systems

“…Lastly, our community analysis results clearly demonstrated that AOM and MC-LR could impact the community structure of biofilm, increasing the relative abundance of bacteria that potentially utilize AOM components and MC-LR. Our finding displays the future potential to harness biofilm activity and functions in BAF for enhanced removal of cyanobacteriaderived contaminants using feasible strategies such as biostimulation and/or bioaugmentation (Horemans et al, 2017;Mikkelson et al, 2015).…”