Environmental pollution size of the Bishkek Solid Waste Landfill and treatment of generated leachate wastewater
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-08-10 |
| Journal | MANAS Journal of Engineering |
| Authors | Venera EDÄ°LBEK KYZY, Nurzat Shaykieva, Kubat Kemelov, Mustafa Dolaz, Mehmet Kobya |
| Institutions | Kyrgyz-TĂŒrkish Manas Ăniversity |
| Citations | 2 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive Summaryâ- Problem Statement: The Bishkek Solid Waste Landfill (BSWL) generates highly stabilized (old) leachate characterized by high COD (1400 mg/L) and low biodegradability (BOD5/COD ratio of 0.014). This untreated leachate is currently polluting local natural ponds and groundwater.
- CF Ineffectiveness: Conventional Coagulation-Flocculation (CF) using optimized dosages of Alum (pH 6.5) and Ferric Chloride (pH 8.5) proved inefficient, achieving a maximum of only 40% COD removal and 14% Ammonia Nitrogen removal.
- EO Efficacy: Electro-Oxidation (EO) using Boron-Doped Diamond (BDD) anodes and Stainless Steel (SS) cathodes was investigated as a highly effective alternative for refractory pollutant destruction.
- Optimal Performance: At the highest tested current (5.0 A, or 208.33 A/m2), the EO process achieved near-complete removal of key pollutants within 260 minutes.
- Key Achievement: The EO process successfully removed 97.9% of COD, 95.5% of Total Organic Carbon (TOC), and 99.8% of Ammonia Nitrogen, demonstrating superior performance over CF for stabilized leachate.
- Conclusion: The study confirms that BDD-based EO is a viable and effective technology for treating the highly polluting, stabilized leachate generated by the irregular Bishkek landfill.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Initial COD | 1400 ± 50 | mg/L | Raw Bishkek Landfill Leachate (BLL) |
| Initial TOC | 540 ± 15 | mg/L | Raw BLL |
| Initial NH3-N | 315 ± 10 | mg/L | Raw BLL |
| Initial pH | 8.1 ± 0.2 | - | Stabilized/Old Leachate characteristics |
| BOD5/COD Ratio | 0.014 | - | Indicates low biodegradability |
| CF Coagulant 1 | Alum (Al2(SO4)3) | - | Optimized at pH 6.5 |
| CF Coagulant 2 | Ferric Chloride (FeCl3) | - | Optimized at pH 8.5 |
| Max COD Removal (CF) | 40 | % | Achieved using 5 g/L FeCl3 dosage |
| EO Anode Material | Boron-Doped Diamond (BDD) | - | Used for high oxidative capacity |
| EO Cathode Material | Stainless Steel (SS) | - | - |
| Electrode Area | 120 | cm2 | Area of both BDD anode and SS cathode |
| Electrode Gap | 1.60 | cm | Distance between electrodes |
| Applied Current (Max) | 5.0 | A | Corresponds to 208.33 A/m2 current density |
| EO Treatment Time | 260 | min | Time required to achieve maximum removal |
| Max COD Removal (EO) | 97.9 | % | Achieved at 5.0 A |
| Max TOC Removal (EO) | 95.5 | % | Achieved at 5.0 A |
| Max NH3-N Removal (EO) | 99.8 | % | Achieved at 5.0 A |
Key Methodologies
Section titled âKey Methodologiesâ- Leachate Characterization: Raw leachate samples were collected from natural lagoons adjacent to the BSWL and stored at 4 °C. Key parameters (COD, TOC, BOD5, NH3-N, pH) were measured according to Standard Methods.
- Coagulation-Flocculation (CF) Testing: Experiments were conducted in a 250 mL jar test apparatus (100 mL working volume).
- CF pH Control: Optimal pH values were maintained: pH 6.5 for Alum and pH 8.5 for Ferric Chloride, adjusted using H2SO4 or NaOH.
- CF Mixing Protocol: Samples underwent rapid mixing (200 rpm, 2 min), followed by slow mixing (30 rpm, 30 min), and a 60 min settling period. Coagulant dosages ranged from 0.10 to 0.50 g/L.
- Electro-Oxidation (EO) Setup: A batch EO reactor (1000 mL volume) was utilized, featuring a BDD plate anode and a SS plate cathode, both 20 x 6 cm (120 cm2 area), separated by 1.60 cm.
- EO Operation: Experiments were run at constant applied currents (1.0 A, 3.0 A, and 5.0 A) using a DC power supply, without the addition of supporting electrolytes, at room temperature (22 ± 3 °C).
- Performance Measurement: Samples were periodically collected, filtered (0.45 ”m), and analyzed for residual COD, TOC, and NH3-N to determine removal efficiencies over 260 minutes.
Commercial Applications
Section titled âCommercial ApplicationsâThe successful application of Boron-Doped Diamond (BDD) electro-oxidation for highly stabilized landfill leachate demonstrates its commercial viability in several advanced water treatment sectors:
- Sanitary Landfill Leachate Management: Essential for treating old or stabilized leachates where biological methods fail due to high concentrations of refractory organic compounds and ammonia.
- Advanced Oxidation Processes (AOPs): Used for the destruction and mineralization of non-biodegradable and toxic pollutants in industrial effluents.
- Refractory Industrial Wastewater Treatment: Applicable to industries generating complex, high-strength wastewater (e.g., pharmaceuticals, pesticides, dyes, and specialty chemicals).
- Water Reclamation and Reuse: BDD technology provides a final polishing step to meet stringent discharge or reuse standards by ensuring near-complete removal of trace contaminants and chemical oxygen demand.
- Electrochemical Disinfection: Utilization of electro-generated active chlorine and hydroxyl radicals for effective disinfection and pathogen control in water systems.
View Original Abstract
The disposal of municipal solid wastes (MSW) is one of the important issues today. The MSW is generally disposed of in a landfill. The disintegration of wastes in landfill generates the wastewater known as leachate and it became one of the budding environmental impacts. The landfill leachate seeps into natural ponds next to the Bishkek (Kyrgyzstan) landfill. The MSWs are dumped with an irregular landfill in Bishkek, and it has been observed that this situation creates many environmental pollution problems (air pollution due to the combustion of wastes and generated biogas, due to leakage of leachate from the landfill) around the landfill. The leachate in the ponds is not treated and leaks into the environment. In this study, the potential of the coagulation-flocculation(CF) and electrooxidation (EO) processes was investigated for the treatment of leachate from the sanitary landfill located in Bishkek-Kyrgyzstan. The initial COD (1400 ± 50 mg/L), TOC (540 ± 15 mg/L), and ammonia nitrogen (315 ± 10 mg/L) from landfill leachate were treated by the CF process as 33, 23, and 14% at pH 6.5 with alum dosage of 5 g/L, and 40, 29 and 10.1% at pH 8.5 with ferric chloride dosage of 5 g/L, respectively.Removal efficiencies at applied currents of 1.0, 3.0, and 5.0 A with an EO reactor using boron-doped diamond (BDD) plate anode and stainless steel (SS) plate cathode were 67.20, 88.30, and 97.90% for COD, 60.10, 85.38, and 95.53% for TOC, and 48.9, 94.6 and 99.8% for ammonia nitrogen, respectively. As a result, it was seen that Bishkekâs irregular solid waste landfilling leachate, which causes environmental pollution, was effectively treated with the EO process. By establishing a regular landfill, Bishkek municipal solid wastes must be disposed of in the landfill and treated of the leachate.