RESUMEN
Due to the accumulation of an enormous amount of plastic waste from municipal and industrial sources in landfills, landfill leachate is becoming a significant reservoir of microplastics. The release of microplastics from landfill leachate into the environment can have undesirable effects on humans and biota. This study provides the state of the science regarding the source, detection, occurrence, and remediation of microplastics in landfill leachate based on a comprehensive review of the scientific literature, mostly in the recent decade. Solid waste and wastewater treatment residue are the primary sources of microplastics in landfill leachate. Microplastic concentration in raw and treated landfill leachate varied between 0-382 and 0-2.7 items L-1. Microplastics in raw landfill leachate are largely attributable to local plastic waste production and solid waste management practices. Polyethylene, polystyrene, and polypropylene are the most prevalent microplastic polymers in landfill leachate. Even though the colors of microplastics are primarily determined by their parent plastic waste, the predominance of light-colored microplastics in landfill leachate indicates long-term degradation. The identified morphologies of microplastics in leachate from all published sources contain fiber and fragments the most. Depending on the treatment method, leachate treatment processes can achieve microplastic removal rates between 3% and 100%. The review also provides unique perspectives on microplastics in landfill leachate in terms of remediation, final disposal, fate and transport among engineering systems, and source reduction, etc. The landfill-wastewater treatment plant loop and bioreactor landfills present unique difficulties and opportunities for managing microplastics induced by landfill leachate.
RESUMEN
In-situ chemical oxidation (ISCO) is a commonly used method for the remediation of environmental contaminants in groundwater systems. However, traditional ISCO methods are associated with several limitations, including safety and handling concerns, rebound of groundwater contaminants, and difficulty in reaching all areas of contamination. To overcome these limitations, novel Controlled-Release Biodegradable Polymer (CRBP) pellets containing the oxidant KMnO4 were designed and tested. The CRBP pellets were encapsulated in Polyvinyl Acetate (CRBP-PVAc) and Polyethylene Oxide (CRBP-PEO) at different weight percentages, baking temperatures, and time. Their release efficiency was tested in water, soil, and water and soil mixture media. Results showed that CRBP-PVAc pellets with 60 % KMnO4 and baked at 120 °C for 2 min had the highest release percentage and rate across different conditions tested. Natural organic matter was also found to be an important factor to consider for in-field applications due to its potential reducing effect with MnO4-. Overall, the use of CRBP pellets offers an innovative and sustainable solution to remediate contaminated groundwater systems, with the potential to overcome traditional ISCO limitations. These findings suggest that CRBP pellets could provide sustained and controlled release of the oxidant, reducing the need for multiple injections and minimizing safety and handling concerns. This study represents an important step towards developing a new and effective approach for ISCO remediation.