Removal of selenium using a novel algal: bacterial process

A process for removing selenium and nitrate from agricultural drainage water using algae and anaerobic bacteria was studied in a field system. Algae were grown in high-rate ponds containing drainage water, and the 178- ± 99-mg/L culture took up 18 ± 13 mg/L${\rm NO}_{3}{}^{-}\text{-}{\rm N}$. The al...

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Bibliographic Details
Published in:Research journal of the Water Pollution Control Federation 1991-07, Vol.63 (5), p.799-805
Main Authors: Gerhardt, M.B. (Brown and Caldwell Consultants, Pleasant Hill, CA), Green, F.B, Newman, R.D, Lundquist, T.J, Tresan, R.B, Oswald, W.J
Format: Article
Language:English
Subjects:
AGUA DE DRENAJE
ALGAE
Anaerobic bacteria
ANAEROBIOSE
ANAEROBIOSIS
BACTERIA
BIOLOGICAL TREATMENT
Chlorides
DRAINAGE WATER
EAU DE DRAINAGE
FARMLAND
FERMENTACION
FERMENTACION METANICA
FERMENTATION
FERMENTATION METHANIQUE
Methane
METHANE FERMENTATION
NITRATE
NITRATES
NITRATOS
Ponds
Productivity
Research Papers
SELENIO
SELENIUM
TERRE AGRICOLE
TIERRAS AGRICOLAS
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Summary:A process for removing selenium and nitrate from agricultural drainage water using algae and anaerobic bacteria was studied in a field system. Algae were grown in high-rate ponds containing drainage water, and the 178- ± 99-mg/L culture took up 18 ± 13 mg/L${\rm NO}_{3}{}^{-}\text{-}{\rm N}$. The algae and drainage water were then transferred to anoxic units where denitrifying and selenate-reducing bacteria, feeding on algae, reduced${\rm NO}_{3}{}^{-}\text{-}{\rm N}$from 100 ± 24 mg/L to less than 10 mg/L at times. Soluble selenium concentration, which was 200-400 μg/L in the influent, decreased only slightly in anoxic units, but speciation of effluent selenium showed that selenate was completely reduced to selenite and other reduced forms. Addition of 10-20 mg/L ferric chloride to the effluent reduced soluble selenium to 7-12 μg/L. Selenium reduction was not inhibited by 2000-4000 mg/L sulfate. Algae not used by denitrifying and selenate-reducing bacteria were fermented to methane in unmixed cylindrical digesters where methane production averaged 0.16 L/g volatile solids introduced.
ISSN:1047-7624
2327-7475