Innovative approach to industrial waste utilization for acid mine drainage remediation and Spent material reuse: A cost-effective circular economy approach

Acid mine drainage (AMD) is a major environmental concern, distinguished by its acidic nature and elevated levels of metal and sulfate ions. Study evaluated the effectiveness of three end-of-life industrial waste materials, bagasse fly ash, iron slag, and red mud, separately in neutralizing AMD and facilitating metal precipitation. A batch test was designed to accomplish this objective, focusing on optimizing factors such as dose, reaction time, and temperature. Metal ions precipitation was effective; however, sulfate ions mitigation was the limitation with industrial waste. To precipitate sulfate ions in the form of ettringite compound CaO and Al(OH)₃ were added. The reaction mechanism for complete treatment was comprehended. The combined treatment approach successfully reduces AMD pollutants to levels within their regulatory limits in treated water. Preliminary cost estimation for AMD remediation was estimated $0.026/L for bagasse fly ash, $0.025/L for iron slag, and $0.022/L for red mud, highlighting significant financial savings along with the advantage of utilizing industrial waste. The study used sludge material after metal removal, to produce eco-friendly fired clay bricks by replacing 10 % of the clay (by weight) and firing at 1050 °C. Cost benefits with sludge utilization suggests additional financial and environmental benefits. This approach presents a sustainable and cost-effective solution for AMD treatment. It also repurposes industrial waste with sludge valorisation and delivers significant environmental as well as economic advantages.