An efficient sequential method for enhanced landfill leachate treatment and detoxification:...

Area of Science:

• Environmental Chemistry
• Water Treatment Technologies
• Advanced Oxidation Processes

Background:

• Organic matter in leachate poses significant environmental challenges.
• Conventional treatment methods often struggle with complete mineralization.
• Developing cost-effective and efficient pre-treatment and advanced oxidation processes is crucial.

Purpose of the Study:

• To investigate a novel sequential treatment process for organic matter mineralization.
• To evaluate the integration of permanganate into electrocoagulation (EC/PM) for enhanced pre-treatment.
• To repurpose iron sludge from EC/PM as a catalyst (SDEC) in subsequent UV-activated peroxymonosulfate (PMS) treatment.

Main Methods:

• Sequential treatment: electrocoagulation/permanganate (EC/PM) followed by UV-activated peroxymonosulfate (PMS) with sludge-derived electrocoagulation (SDEC).
• Optimization of key operating parameters for the treatment sequence.
• Comprehensive leachate analysis: COD, BOD, TOC, ammonia, average oxidation state, biodegradability, and spectroscopic methods.

Main Results:

• Achieved high removal efficiencies: 98.9% COD, 94.9% BOD, 96.4% TOC, and 97.7% ammonia.
• Spectroscopic analysis indicated breakdown of organic matter into smaller, oxidized, and acidic molecules, with increased aliphatic and reduced aromatic content.
• Improved BOD5/COD ratio to 0.55, signifying enhanced biodegradability and reduced toxicity.

Conclusions:

• The EC/PM followed by PMS/SDEC/UV treatment sequence is highly effective for organic matter mineralization.
• Repurposing iron sludge as SDEC offers a cost-effective catalytic solution.
• The treated leachate is suitable for subsequent biological treatment, demonstrating reduced environmental risk.