Application of boron-doped diamond, Ti/IrO₂, and Ti/Pt anodes for the electrochemical oxidation of landfill leachate biologically pretreated by moving bed biofilm reactor

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Electrochemistry

Background:

• Conventional biological treatments struggle with stabilized landfill leachate in Indonesia.
• Leachates contain high organic and nitrogenous compounds, necessitating advanced treatment.
• A combined biological-electrochemical approach offers a promising solution.

Purpose of the Study:

• To evaluate the efficacy of a combined Moving Bed Biofilm Reactor (MBBR) and electrochemical oxidation system.
• To investigate the impact of different anode types (BDD, Ti/IrO2, Ti/Pt) and applied currents on leachate treatment.
• To assess the removal of organic compounds and total nitrogen from landfill leachate.

Main Methods:

• Utilized a Moving Bed Biofilm Reactor (MBBR) followed by electrochemical oxidation.
• Employed boron-doped diamond (BDD), Ti/IrO2, and Ti/Pt anodes.
• Varied applied currents at 350, 400, and 450 mA to optimize treatment.

Main Results:

• The boron-doped diamond (BDD) anode achieved 85% chemical oxygen demand (COD) removal at 350 mA with 36.9 Wh/L energy consumption.
• Ti/Pt anode yielded 78% COD removal at 400 mA (56.7 Wh/L), while Ti/IrO2 showed 76% at 350 mA (58.9 Wh/L).
• MBBR pretreatment removed 46-95% of nitrogenous compounds, with partial conversion to nitrates; electrochemical oxidation showed limited nitrogen reduction.

Conclusions:

• The MBBR-electrochemical oxidation combination effectively reduces organic pollutants in landfill leachate.
• Boron-doped diamond anodes offer superior performance and energy efficiency for leachate treatment.
• Further optimization is needed for efficient total nitrogen removal in combined systems.