N-PROPANOL PRODUCTION DURING ETHANOL DEGRADATION USING ANAEROBIC GRANULES

n-Propanol formation and consumption during ethanol oxidation by anaer obic brewery granules was investigated. The granules were taken from a n UASB reactor fed with a synthetic brewery waste water. Ethanol degra dation assays and an isotopic assay using C-13-labeled ethanol and bic arbonate were performed. Intermediate products propionate, n-propanol, acetate, hydrogen, formate and carbon monoxide were observed. Results have shown a consistent and reproducible trend of ethanol being conve rted to, primarily intermediates propionate and acetate with some accu mulation of n-propanol. Hydrogen and carbon monoxide concentration acc umulated to 1120 and 50 ppm in the gas phase, respectively. Methane an d carbon dioxide were the terminal products, Bicarbonate was not a sig nificant contributor of carbon for n-propanol production based on C-13 assay results. From reaction energetics analysis and ethanol degradat ion assays, reactions of hydroformylation of ethanol with carbon monox ide and hydrogen, ethanol condensation, propionate reduction, and, eth anol oxidation coupled with propionate reduction are potentially respo nsible for the formation of propanol during anaerobic ethanol oxidatio n. Carbon monoxide is likely an additional carbon to ethanol during th e formation of n-propanol. Hydrogen appeared to play a strong role as a driving force governing reactions involving propionate. Copyright (C ) 1996 Elsevier Science Ltd