Three-Dimensional Packed-Bed Electrochemical Reactor Design for Selective Selenite Reduction in Water.

Area of Science:

• Environmental Chemistry
• Electrochemistry
• Wastewater Treatment

Background:

• Selenium contamination in flue-gas desulfurization (FGD) wastewater presents significant environmental challenges.
• Conventional treatment methods often face limitations in efficiency and require regeneration.

Purpose of the Study:

• To develop and optimize a three-dimensional electrochemical reactor (3DER) for efficient selenium removal from FGD wastewater.
• To evaluate the performance of the 3DER under various operating conditions and in real wastewater matrices.

Main Methods:

• A 3DER utilizing carbon-based particle electrodes (PEs) was designed and optimized.
• Reactor performance was assessed by varying PE geometry, recirculation rate, cell potential, and anode-to-cathode chamber ratio.
• System efficiency was tested using synthetic and real FGD wastewater, monitoring selenium removal rates and energy consumption.

Main Results:

• The optimized 3DER configuration achieved steady selenium removal, improving over 12 hours in synthetic wastewater.
• In real FGD wastewater, the system demonstrated robust performance without regeneration, achieving high removal rates and low energy consumption.
• Competing ions in real wastewater enhanced selenium reduction, and elevated selenium loadings further boosted removal efficiency.

Conclusions:

• The 3DER offers a resilient and efficient solution for selenium removal from challenging industrial wastewater streams.
• The system's performance, low energy consumption, and ability to handle high selenium loads support its potential for large-scale application.
• This technology provides a promising approach for mitigating selenium pollution from coal-fired power plants.