BIOLOGICAL SULFATE REDUCTION IN A UASB REACTOR FED WITH ETHANOL AS THE ELECTRON-DONOR

Citation
Sv. Kalyuzhnyi et al., BIOLOGICAL SULFATE REDUCTION IN A UASB REACTOR FED WITH ETHANOL AS THE ELECTRON-DONOR, Microbiology, 66(5), 1997, pp. 562-567
Citations number
14
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
ISSN journal
0026-2617
Volume
66
Issue
5
Year of publication
1997
Pages
562 - 567
Database
ISI
SICI code
0026-2617(1997)66:5<562:BSRIAU>2.0.ZU;2-5
Abstract
A process of biological reduction of sulfate was investigated using a 3.2-1 laboratory UASB reactor (35 degrees C) with conventional anaerob ic sludge and ethanol (a relatively cheap reagent) as the sole electro n donor and carbon source. High sulfate-conversion efficiencies (SCE) of up to 80% were obtained at sulfate loading rates (SLR) of up to 6 g SO42-/(1 day) (hydraulic retention times (HRT), 5-0.85 days; influent sulfate concentrations, 0.84-5 g/l). Further increasing the SLR to 10 g SO42-/(1 day) caused the SCE to decrease to 60%. The SCE slightly d ecreased with a decrease in HRT, was almost independent of the influen t sulfate concentration, and linearly increased with the increase in m edium DH, i.e., with the decrease in the concentration of undissociate d H2S. Thus, to reach a high SCE at a high SLR, additional measures sh ould be taken to eliminate undissociated H2S from the reactor medium. Sulfate-reducing bacteria (SRB) won the competition with methanogens f or the energy and carbon sources in this system. The predominance of S RB was continuously enhanced with time, although complete cessation of methane production was not observed even after 8 months of the experi ment. It is speculated that the microbial sulfate reduction can be fol lowed by a stripping of the H2S formed or chemical (biological) proces ses of further conversion of H2S to sulfur and/or sulfuric acid.