Unveiling The Potential of Microwave Plasma Treated Char For Sustainable Automotive Shredder Residue (ASR) Management and Reduced Ecological Risk Of Cadmium

<p>Introduction: This study explores the effectiveness of microwave plasma pyrolysis in reducing heavy metal concentrations, specifically cadmium, in automobile shredder residue (ASR). </p> <p> Methods: The ASR was subjected to plasma pyrolysis at microwave power levels ranging from 800 to 1000W, resulting in a significant decrease in heavy metal concentration in the char. Utilizing the Bureau Communautaire de Référence (BCR) sequential extraction method, a standardized procedure developed by the European Commission, we assessed the chemical speciation and matrix properties of the char. The results indicated that microwave plasma treatment effectively decreased the bioavailable forms of cadmium. After 6 minutes of pyrolysis at 1000W, the exchangeable and acidsoluble fractions (F1) dropped to 10%, while the reducible fraction (F2) fell to 12%. </p> <p> Results: This treatment resulted in a substantial increase in the oxidizable (F3) and residue (F4) fractions, which reached 27% and 51%, respectively. Importantly, the potential ecological risk of cadmium decreased significantly, with the risk index (Er) dropping from 164.91 to 28.45, aligning with Taiwan's regulatory standards for non-hazardous waste. </p> <p> Conclusion: These findings suggest that microwave plasma pyrolysis is a promising and sustainable approach for the disposal of ASR, offering an environmentally friendly alternative for waste management. This study provides valuable insights for policymakers, environmental scientists, and industries seeking effective solutions for ASR treatment.</p>