A novel elemental sulfur-based mixotrophic denitrifying membrane bioreactor for simultaneous Cr(VI) and nitrate reduction.
This study aims at investigating the simultaneous nitrate and chromate reduction by combining the advantages of sulfur-based autotrophic denitrification, heterotrophic denitrification and membrane bioreactor (MBR) technologies. A laboratory-scale MBR equipped with hydrophilic flat sheet polyethersulfone (PES) membranes (0.45μm) was used to evaluate the performance of mixotrophic denitrification at varying nitrate and Cr(VI) concentrations. Methanol was supplied at C/N (mg methanol/mg NO3--N) ratio of 1.33. In the absence of Cr(VI), almost complete denitrification of 50mg/L NO3--N was obtained and the methanol requirement (3.60±0.9mg COD/(mg NO3--N)) for heterotrophic denitrifiers, was quite close to the theoretical value (3.7mg COD/(mg NO3--N)). Around 54% of the influent nitrate was denitrified by heterotrophs and the rest (56%) was denitrified by autotrophic sulfur oxidizers. The effluent sulfate averaged around 200mg/L, which was below than the theoretical sulfate concentration if autotrophic denitrification process was used alone. Autotrophic denitrification activity completely ceased at 5mg/L Cr(VI), but heterotrophic denitrification did not show any inhibition. Almost complete chromate and nitrate reduction was observed at 1mg/L Cr(VI). MBR was operated for around 200days and a weekly physical membrane cleaning was enough at a flux of 15 LMH.
['Sahinkaya|Erkan|E|', 'Yurtsever|Adem|A|', 'Ucar|Deniz|D|']
D019149:Bioreactors D002857:Chromium D058440:Denitrification D052836:Heterotrophic Processes D006863:Hydrogen-Ion Concentration D008567:Membranes, Artificial D000432:Methanol D009566:Nitrates D010084:Oxidation-Reduction D013431:Sulfates D013455:Sulfur D014462:Ultrafiltration D018508:Water Purification
Membrane bioreactor Sulfur-based autotrophic denitrification Autotrophic denitrification Mixotrophic denitrification Drinking water