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Complementary treatment of municipal landfill leachate for chemical oxygen demand and color removal, case study: Waste Management Organization of Tehran Municipality

Sinaei, Yahya | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58161 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Raie, Mohammad
  7. Abstract:
  8. Landfill leachate, due to its content of resistant organic and inorganic pollutants, is considered one of the most significant environmental challenges. This study aimed to investigate advanced and complementary treatment methods for removing Chemical Oxygen Demand (COD) and color (at wavelengths of 455 and 465 nm) from treated leachate (subjected to biological and chemical treatment) from the Aradkouh landfill in Tehran. In the first phase, the combined oxidation and coagulation-flocculation process using two ferrate (VI)-based compounds (soluble sodium ferrate (Fersol) and potassium ferrate powder) was evaluated. Results showed that both substances performed best under highly acidic conditions (pH= 1), with their optimal dosages improving COD and color removal. Potassium ferrate achieved optimal COD and color removal efficiencies of approximately 45% and 64-65%, respectively, with rapid mixing for 15 minutes, while Fersol provided a maximum COD removal of about 34%. However, due to the high cost of chemicals, the need for extreme pH adjustments, the large volume of sludge produced, and the lower COD removal efficiency, these methods were deemed less feasible from operational and economic perspectives. In the second phase, the advanced oxidation process (UV-H₂O₂) was evaluated under varying conditions of pH, hydrogen peroxide dosage, and reaction time. Results indicated that optimal performance occurred at neutral pH, with a hydrogen peroxide dosage of 2000 mg/L and a reaction time of 120 minutes, achieving COD removal of 68% (reducing it to about 324 mg/L) and color removal of 98%. However, shorter reaction times (less than 60 minutes) resulted in incomplete reactions and suboptimal efficiencies. In the third phase, the performance of adsorption filters containing granular activated carbon (GAC) and zeolite was assessed. When different volumes of leachate passed through the filters, it was found that for smaller volumes (100 mL), GAC achieved approximately 39% and 32%, and zeolite achieved 33% and 13% COD and color removal, respectively. However, with increasing volumes, the adsorption capacity of the filters decreased. Finally, combining the UV-H₂O₂ process (under maximum efficiency conditions) with effluent passage through adsorption filters increased final COD removal efficiency to approximately 80% with the carbon filter and 78% with the zeolite filter, while the effluent color remained within standard limits. A comparison of operational costs showed that the UV-H₂O₂ process, in addition to achieving higher pollutant removal efficiencies, incurred lower costs compared to potassium ferrate
  9. Keywords:
  10. Leachate ; Chemical Oxygen Demand (COD) ; Decolorization ; Flocculation ; Coagulation ; Advanced Oxidation Process ; Granular Activated Carbon ; Zeolite ; Adsorption Filters ; Tertiary Treatment ; Soluble Sodium Ferrate (Fersol) ; Potassium Ferrate ; Waste Management

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