title: Simultaneous bioreduction of nitrate and chromate using sulfur-based mixotrophic denitrification process.
abstract: This study aims at evaluating simultaneous chromate and nitrate reduction using sulfur-based mixotrophic denitrification process in a column reactor packed with elemental sulfur and activated carbon. The reactor was supplemented with methanol at C/N ratio of 1.33 or 2. Almost complete denitrification was achieved at influent NO3(-)-N and Cr(VI) concentrations of 75 mg/L and 10mg/L, respectively, and 3.7h HRT. Maximum denitrification rate was 0.5 g NO3(-)-N/(L.d) when the bioreactor was fed with 75 mg/L NO3(-)-N, 150 mg/L methanol and 10mg/L Cr(VI). The share of autotrophic denitrification was between 12% and 50% depending on HRT, C/N ratio and Cr(VI) concentration. Effluent total chromium was below 50 μg/L provided that influent Cr(VI) concentration was equal or below 5mg/L. DGGE results showed stable microbial community throughout the operation and the presence of sulfur oxidizing denitrifying bacteria (Thiobacillus denitrificans) and Cr(VI) reducing bacteria (Exiguobacterium spp.) in the column bed.
authors.affiliation: Istanbul Medeniyet University, Bioengineering Department, Goztepe, Istanbul, Turkey. Electronic address: erkansahinkaya@yahoo.com.
authors.forename: Erkan
authors.initials: E
authors.lastname: Sahinkaya
authors.forename: Adem
authors.initials: A
authors.lastname: Kilic
authors.forename: Beste
authors.initials: B
authors.lastname: Calimlioglu
authors.forename: Yasemin
authors.initials: Y
authors.lastname: Toker
mesh_terms: D000327:Adsorption; D001483:Base Sequence; D019149:Bioreactors; D002840:Chromates / Q000737:chemistry*; D017931:DNA Primers; D058440:Denitrification; D004926:Escherichia coli / Q000235:genetics; D009566:Nitrates / Q000737:chemistry*; D010084:Oxidation-Reduction; D016133:Polymerase Chain Reaction; D013455:Sulfur / Q000737:chemistry*
chemical_list: D002840:Chromates; D017931:DNA Primers; D009566:Nitrates; D013455:Sulfur
keywords: Chromium; Denitrification; Mixotrophic denitrification; Sulfur based denitrification