Iron and nickel nanoparticles role in volatile fatty acids production enhancement: Functional genes and bacterial taxonomy in an anaerobic fluidized bed reactor

• Published in: Biochemical engineering journal Vol. 187; p. 108656
• Main Authors: Moura, A.G.L., Delforno, T.P., Rabelo, C.A.B.S., Kumar, G., Silva, E.L., Varesche, M.B.A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2022
• Subjects: Anaerobic fluidized bed reactor; Clostridium butyricum; Dark fermentation; Metagenome; Nanoparticles; Nanoparticles; Anaerobic fluidized bed reactor; Clostridium butyricum; Dark fermentation; Metagenome
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2022.108656

This study is the first report that describes Iron (16.7 mg Fe0 g-1) and Nickel (0.04 mg Ni0 g-1) nanoparticles (NPs) immobilization on the support material of an Anaerobic Fluidized Bed Reactor (AFBR-NP) and the assessment of its influence on fermentation pathway when compared with a reactor without NPs (AFBR-Control). AFBRs were operated at initial pH 6.8, 37 °C, 3.0 h Hydraulic Retention Time. Natural fermentation along with bioaugmentation with Clostridium butyricum were used as inoculation strategy. Both reactors were fed with glucose as main substrate (56 ± 6 and 21 ± 2 g COD L-1 d-1 at operational Stages I and II, respectively). 78–98% higher Volatile Fatty Acid (VFA) was observed on AFBR-NP. Metals higher availability specifically favored butyric (1.04 ± 0.37 g L-1) and acetic (1.22 ± 0.33 g L-1) acid production metabolic route on AFBR-NP. Under the same operational conditions, lactic acid was observed as main metabolite on AFBR-Control (1.23 ± 0.25 g L-1). Enzymes related to butyric (butyryl-CoA dehydrogenase, phosphate butyryltransferase, butyrate kinase) and propionic acid (pyruvate-ferredoxin oxidoreductase) metabolic routes were identified on AFBR-NP reactor biofilm. Through these results, it is possible to infer that Fe0 and Ni0 NPs could effectively improve VFA production and the fermentation process. [Display omitted] •Metal nanoparticles were immobilized on support material of a continuous reactor.•Using metagenome analyses, enzymes on biofilm of AFBR-NP were described.•Metals higher availability favored butyric and acetic acid production.•Nickel and Iron nanoparticles were able to improve VFA production by 78–98%.