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Selenite reduction by a denitrifying culture: batch- and packed-bed reactor studies
Sridhar Viamajala1, Yared Bereded-Samuel, William A Apel
1National Bioenergy Center, National Renewable Energy Laboratory, 1617 Cole Blvd. MS 3511, Golden, CO 80401, USA.
Applied Microbiology and Biotechnology
|January 25, 2006
Summary
Bacterial consortia can reduce selenite under denitrifying conditions. Optimal selenium removal from waste streams occurs with immobilized cultures under nitrate-limited conditions, avoiding nitrite inhibition.
Area of Science:
- Environmental microbiology
- Bioremediation of selenium
Background:
- Selenite contamination in industrial wastewater poses environmental risks.
- Denitrifying bacteria can transform selenite, but process efficiency is affected by electron acceptors.
Purpose of the Study:
- To investigate selenite reduction by denitrifying bacteria under various conditions.
- To evaluate the effectiveness of immobilized cultures for selenium removal from waste streams.
Main Methods:
- Enrichment of bacterial consortia from oil refinery waste sludge.
- Batch and continuous-flow experiments using packed-bed columns with immobilized cultures.
- Manipulation of nitrate and nitrite concentrations as electron acceptors.
Main Results:
- Selenite reduction was inhibited by high nitrite concentrations.
- Continuous nitrate feeding showed limited selenite removal.
- Pulsed nitrate feeding and low-concentration continuous nitrate feeding significantly enhanced selenium removal and retention.
Conclusions:
- Immobilized denitrifying bacteria show potential for selenium removal from wastewater.
- Nitrate-limited conditions are crucial for efficient selenite reduction and selenium recovery.
- Optimizing electron acceptor supply is key to overcoming nitrite inhibition in bioremediation processes.
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