Treatment of bio-digester effluent by electrocoagulation using iron electrodes

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Electrochemistry

Background:

• Bio-digester effluent (BDE) presents significant pollution challenges due to high chemical oxygen demand (COD).
• Conventional treatment methods may not fully address the pollutant load, necessitating advanced techniques.
• Electrocoagulation (EC) is a promising technology for wastewater treatment.

Purpose of the Study:

• To investigate the reduction of COD in BDE using a batch electrocoagulation reactor with iron electrodes.
• To evaluate the individual and interactive effects of key operational parameters on COD removal efficiency.
• To determine the optimal conditions for maximum COD and color reduction.

Main Methods:

• Utilized a batch electrocoagulation (EC) reactor with iron electrodes.
• Employed a central composite (CC) experimental design to study four parameters: current density, initial pH, inter-electrode distance, and electrolysis time.
• Analyzed results using Pareto analysis of variance (ANOVA) and a second-order regression model.

Main Results:

• Achieved maximum COD reduction of 50.5% and color reduction of 95.2% under optimized conditions.
• The second-order regression model demonstrated a high coefficient of determination (R²=0.8547), indicating satisfactory prediction accuracy.
• Pareto analysis of variance identified significant parameters influencing COD removal efficiency.

Conclusions:

• Electrocoagulation is an effective method for reducing COD and color in bio-digester effluent.
• The study identified optimal operating parameters for the EC process in distillery wastewater treatment.
• EC can serve as a pre-treatment step to reduce pollution load before aerobic treatment, aiding compliance with discharge standards.