Murdoch University Research Repository

Welcome to the Murdoch University Research Repository

The Murdoch University Research Repository is an open access digital collection of research
created by Murdoch University staff, researchers and postgraduate students.

Learn more

Sequential removal of selenate, nitrate and sulfate and recovery of elemental selenium in a multi-stage bioreactor process with redox potential feedback control

Yan, S., Cheng, K.Y., Ginige, M.P., Morris, C., Deng, X., Li, J., Song, S., Zheng, G., Zhou, L. and Kaksonen, A.H. (2022) Sequential removal of selenate, nitrate and sulfate and recovery of elemental selenium in a multi-stage bioreactor process with redox potential feedback control. Journal of Hazardous Materials, 424 . Art. 127539.

[img]
Preview
PDF - Published Version
Download (5MB) | Preview
Free to read: https://doi.org/10.1016/j.jhazmat.2021.127539
*No subscription required

Abstract

Bioreduction can facilitate oxyanions removal from wastewater. However, simultaneously removing selenate, nitrate and sulfate and recovering high-purity elemental selenium (Se0) from wastewater by a single system is difficult and may lead to carcinogenic selenium monosulfide (SeS) formation. To solve this issue, a two-stage biological fluidized bed (FBR) process with ethanol dosing based on oxidation-reduction potential (ORP) feedback control was developed in this study. FBR1 performance was first evaluated at various ORP setpoints (between −520 and −360 mV vs. Ag/AgCl) and elevated sulfate concentration. Subsequently, ethanol-fed FBR2 was used to reduce sulfate from FBR1 effluent, followed by an aerated sulfide oxidation reactor (SOR). At − 520 mV ≤ ORPs ≤ − 480 mV, FBR1 removed 100 ± 0.1% nitrate and 99.7 ± 0.3% selenate without sulfate reduction. At ORPs ≥ − 440 mV, selenate reduction was incomplete, whereas nitrate removal remained stable. Se0 recovery efficiency from FBR1 effluent was 37.5% with 71% Se purity. FBR2 converted 86% of the remaining sulfate in FBR1 effluent to hydrogen sulfide, but the over-oxidation of dissolved sulfide in SOR decreased the overall sulfate removal efficiency to ~46.3%. Overall, the two-stage FBR process with ORP feedback dosing of ethanol was effective for sequentially removing selenate, nitrate and sulfate and recovering Se0 from wastewater.

Item Type: Journal Article
Murdoch Affiliation(s): IT, Media and Communications
Publisher: Elsevier BV
Copyright: © 2021 The Author(s).
URI: http://researchrepository.murdoch.edu.au/id/eprint/63067
Item Control Page Item Control Page

Downloads

Downloads per month over past year