Selenium Removal from Wastewater by Microbial Transformation and Volatilization

Area of Science:

• Environmental Microbiology
• Bioremediation
• Trace Element Chemistry

Background:

• Selenium (Se) is an essential trace element for humans and animals, but toxic at high concentrations.
• Wastewater contamination with selenium poses environmental and health risks.
• Microbial processes offer a promising avenue for selenium remediation.

Purpose of the Study:

• To investigate the role of microbes in removing selenium from contaminated wastewater.
• To explore biological transformation and volatilization as selenium removal mechanisms.
• To identify specific microbial strains with high selenium biotransformation capabilities.

Main Methods:

• Laboratory study using contaminated wastewater.
• Isolation and testing of microbial strains, including Bacillus cereus.
• Analysis of selenium transformation into elemental selenium (Se0) and volatile selenium compounds.
• Assessment of microbial reduction, methylation, and volatilization processes.

Main Results:

• Bacillus cereus effectively reduced selenate and selenite to elemental selenium (Se0).
• This bacterial strain also transformed selenium into volatile organic compounds.
• Microbial biotransformation and volatilization were confirmed as key selenium removal pathways.
• Substrates like wheat straw and biosolid-WTR-sand supported microbial selenium removal.

Conclusions:

• Microbial reduction, methylation, and volatilization are crucial for bioremediating selenium-contaminated wastewater.
• Bacillus cereus exhibits significant potential for selenium removal from wastewater.
• Understanding these microbial processes is vital for developing effective selenium remediation strategies.