Removal of soluble selenium by a selenate-reducing bacterium Bacillus sp. SF-1

Area of Science:

• Environmental Microbiology
• Bioremediation
• Wastewater Treatment

Background:

• Industrial wastewater often contains toxic selenium compounds.
• Effective biological methods are needed for selenium removal.
• Selenium contamination poses environmental and health risks.

Purpose of the Study:

• To isolate and characterize a bacterial strain for selenium removal from industrial wastewater.
• To investigate the biological mechanism of selenium transformation by the isolated strain.
• To evaluate the efficiency of a sequential selenium removal system.

Main Methods:

• Isolation of Bacillus sp. strain SF-1 from selenium-contaminated sediment.
• Anaerobic cultivation using lactate as an electron donor.
• Monitoring of selenium reduction from selenate to elemental selenium.
• Assessing the sequential treatment capability of the bacterial strain.

Main Results:

• Bacillus sp. strain SF-1 was isolated and identified.
• The bacterium anaerobically reduces selenate to selenite and then to insoluble elemental selenium.
• Elemental selenium precipitates intracellularly and extracellularly.
• Selenite accumulation was transient due to a higher selenate reduction rate.
• A sequential system demonstrated efficient removal of 0.5 mM selenate daily.

Conclusions:

• Bacillus sp. strain SF-1 is a promising candidate for biological selenium removal.
• The bacterium's metabolic pathway facilitates the transformation of soluble selenium into elemental selenium.
• The developed sequential treatment system is effective for industrial wastewater remediation.