Fluoride removal using a rotating anode electro-coagulation reactor: Parametric optimization using response surface...

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Chemical Engineering

Background:

• Fluoride in drinking water causes dental and skeletal fluorosis.
• Effective and economical fluoride removal methods are crucial for public health.
• Existing methods require optimization for efficiency and cost-effectiveness.

Purpose of the Study:

• To intensify fluoride removal using a rotating anode electro-coagulation (EC) reactor.
• To model and optimize EC process parameters for maximum fluoride removal efficiency.
• To evaluate the economic viability and environmental safety of the optimized process.

Main Methods:

• Utilized Response Surface Methodology (RSM) with central composite design (CCD) for optimization.
• Varied operational parameters: rotation speed (20-80 RPM), current (0.2-1.0 A), initial fluoride concentration (8-40 mg/L), and time (15-75 min).
• Analyzed removal kinetics (second-order model) and isotherms (Sips model).
• Conducted cost analysis and sludge characterization (XRD, FTIR, TCLP).

Main Results:

• Achieved a maximum predicted fluoride removal of 96.87% and experimental removal of 95.40% under optimized conditions.
• Optimized parameters: 32 mg/L initial fluoride, 0.8 A current, 60 min, and 60 RPM.
• Determined an operational cost of 0.256 USD/m³ for 93.49% fluoride removal at specific conditions.
• Sludge characterization confirmed safe disposal potential.

Conclusions:

• The rotating anode EC reactor, optimized via RSM, is highly effective for fluoride removal.
• The process presents a cost-effective and environmentally safe solution for mitigating fluoride contamination in drinking water.
• The study demonstrates a promising approach for sustainable water treatment.