The formation and activity of an As(III)-oxidising biofilm in a bioreactor, using pozzolana as bacterial growth support, was studied for the purpose of optimising fixed-bed bioreactors for bioremediation. After 60 days of continuous functioning with an As(III)-contaminated effluent, the active biofilm was found to be located mainly near the inflow rather than homogeneously distributed. Biofilm development by the CAsO1 bacterial consortium and by Thiomonas arsenivorans was then studied both on polystyrene microplates and on pozzolana. Extra-cellular polymeric substances (EPS) and yeast extract were found to enhance bacteria attachment, and yeast extract also appears to increase the kinetics of biofilm formation. Analysis of proteins, sugars, lipids and uronic acids indicate that sugars were the main EPS components. The specific As(III)-oxidase activity of T. arsenivorans was higher (by ninefold) for planktonic cells than for sessile ones and was induced by As(III). All the results suggest that the biofilm structure is a physical barrier decreasing As(III) access to sessile cells and thus to As(III)-oxidase activity induction. The efficiency of fixed-bed reactors for the bioremediation of arsenic-contaminated waters can be thus optimised by controlling different factors such as temperature and EPS addition and/or synthesis to increase biofilm density and activity.
Core Ideas Incorporation of a cover crop improved ethanol and biomass yield regardless of harvest time. Stover‐only treatments yielded greater ethanol and biomass when harvest in the fall. Despite differences in fermentable sugars among feedstocks, biomass yield was the strongest driver of per hectare ethanol yield. Corn (Zea mays L.) stover is readily available and can be used as a feedstock for cellulosic ethanol. The addition of a winter annual cereal crop to the corn stover system could increase potential ethanol yield by adding harvestable biomass. The objective of this study was to evaluate the potential bioethanol yield resulting from the harvest of mixed stands of corn stover interseeded with winter cereals. The winter cereal crop factor consisted of three treatments; cereal rye (Secale cereale L.), triticale (Triticale hexaploide Lart.), and no winter cereal crop (control). The harvest time factor consisted of two treatments; a two‐harvest system (fall + spring), and a one‐harvest system (fall or spring). Two‐harvest feedstock ethanol content [EtOH] was the greatest (0.305 kg kg−1 and 0.307k g kg−1) followed by the spring‐harvested stover (0.201 kg kg−1). Biomass production and [EtOH] were then multiplied to calculate ethanol yields. Ethanol yield (L ha−1) decreased by 47% when stover‐only feedstock was harvested in the spring compared to the fall. When only considering a single harvest system, incorporation of a cover crop did improve ethanol yield by 242 L ha−1 at spring harvest. The two‐harvest mixed feedstock system was the most productive with 41.8% greater ethanol yield when compared to the single harvest. Overall, the mixed biomass feedstocks resulting from the incorporation of a winter annual cereal with corn stover improved biomass yield and [EtOH] relative to stover‐only feedstocks.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.