Black tea waste/iron slag reactive filter media-electrokinetic for mixed heavy metals treatment from contaminated site

Electrokinetic (EK) remediation is a cutting-edge technique used for extracting heavy metals from soils by applying an electric field. This study explores the integration of EK remediation with reactive filtration media (RFM) composed of recycled waste materials of powder iron slag/black tea waste (PIS/BTW) and granular iron slag/black tea waste (GIS/BTW) to improve the removal efficiency of single and mixed heavy metals from kaolinite and natural soils. Results demonstrated that PIS/BTW significantly outperformed GIS/BTW in heavy metal extraction, achieving 98.75 % copper removal compared to 90.06 % with GIS/BTW. Recycled RFMs achieved excellent copper removal, reaching 91.28 % for PIS/BTW and 84.90 % for GIS/BTW over 3 weeks. Specific energy consumption (SEC) increased with treatment durations, ranging from 0.055 to 0.254 kWh kg⁻¹ in kaolin soil, while 0.344 kWh kg⁻¹ increased in natural soil. For a heavy metals mixture in kaolinite soil, the removal of copper, nickel, and zinc achieved 97.15 %, 98.30 %, and 96.68 %, respectively, after 4 weeks, while in natural soil, the removal rates for copper, nickel, and zinc were 16.39 %, 89.22 %, and 84.38 % after 5 weeks. The alkaline pH of the RFMs facilitated the adsorption and precipitation of metal ions, contributing to their immobilization. The research study demonstrated the effectiveness of using recyclable and eco-friendly RFMs to optimize EK remediation, providing a sustainable and efficient solution for addressing heavy metal contamination in soils.