Entrapped elemental selenium nanoparticles affect physicochemical properties of selenium fed activated sludge

Area of Science:

• Environmental Science
• Materials Science
• Biotechnology

Background:

• Wastewater treatment plants utilize activated sludge systems for contaminant removal.
• Selenium contamination in wastewater poses environmental and health risks.
• Current selenium removal methods require further optimization for efficiency and characterization.

Purpose of the Study:

• To characterize selenium-fed activated sludge flocs for improved selenium removal.
• To investigate the physicochemical properties of activated sludge after selenium nanoparticle entrapment.
• To understand the impact of elemental selenium nanoparticles on sludge floc characteristics.

Main Methods:

• Analysis of selenium-fed activated sludge flocs using advanced characterization techniques.
• Comparison of selenium-fed sludge with control sludge not exposed to selenite.
• Assessment of floc settling rates, hydrophilicity, dewaterability, and surface charge density.

Main Results:

• Over 94% of trapped selenium exists as elemental selenium nanoparticles (nanospheres and nanorods).
• Selenium-fed sludge exhibits faster settling, increased hydrophilicity, and reduced dewaterability.
• Surface charge density became less negative, and Al/Mg distribution was altered in selenium-fed sludge.

Conclusions:

• Elemental selenium nanoparticle formation and entrapment significantly alter activated sludge floc properties.
• Understanding these changes is crucial for optimizing selenium removal processes.
• The study provides foundational data for developing novel selenium bioremediation strategies.