Landfill leachate treatment by sequential membrane bioreactor and electro-oxidation processes

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Chemical Engineering

Background:

• Old landfill leachate presents significant treatment challenges due to high contamination levels.
• Seasonal variations impact leachate characteristics and treatment process efficiency.
• Effective treatment requires advanced oxidation and biological processes.

Purpose of the Study:

• To optimize and evaluate a combined membrane bioreactor (MBR) and electro-oxidation process (EOP) for treating highly contaminated landfill leachate.
• To determine optimal operating conditions for both MBR and EOP.
• To assess the impact of seasonal variations on treatment performance.

Main Methods:

• A high-performance membrane bioreactor (MBR) with ultrafiltration was employed.
• Electro-oxidation process (EOP) using boron-doped diamond (BDD) electrodes was utilized.
• Processes were optimized for raw and pretreated landfill leachate, considering seasonal variations.

Main Results:

• Optimal MBR conditions (1.2 gCOD/L/day, 80 days SRT) achieved 63% COD, 35% TOC, 98% NH₄⁺, and 52% P removal.
• Optimal EOP conditions (3 A, 120 min) were identified.
• EOP effluent toxicity was noted, with removal via stripping or sludge assimilation when used as pretreatment.
• Energy consumption for EOP decreased from 22 to 16 kWh/m³ for treated and raw leachate, respectively.

Conclusions:

• The combined MBR-EOP system demonstrates effective treatment of challenging landfill leachate.
• Optimized operating parameters are crucial for maximizing contaminant removal.
• EOP can be a viable pretreatment or post-treatment step, but effluent toxicity requires management.