Fly ash-induced groundwater contamination and magnetic nanoparticles as an innovative adsorbent for remediation: A critical review

India generates approximately 75 % of its total electricity from coal-based thermal power plants, resulting in the daily production of thousands of tons of fly ash. The last decade, the coal-based power industry has increased its capacity by 32 GW, contributing to over 64 % of the total new additions, leading to a rise in coal. This fly ash requires more than 30,000 ha of land for disposal in nearby region. The fly ash accumulates in the ash pond and leaches hazardous pollutants in to the ground water thereby contaminating the water. The ash residues contain elements like: F, Ca, Pb, Hg, As, Al, Se, Cd, Cr, Mn and others. This contaminated water not only possess a threat to the mankind but also to flora and fauna surrounding the water body. This text provides comprehensive coverage of several heavy metals and their impacts on human health. This review article also addresses several techniques for water purification and their performance. The magnetic nano-adsorbents show promise due to their ability to be magnetically separated from the slurry phase into the thicker sludge phase. This paper provides detailed coverage of magnetic nanoparticles as adsorbents for the removal of contaminants.