The invention relates to the use of maghemite nanoparticles at pH < 5 to remove sulphate, manganese, copper, nickel, cobalt and zinc metal ions from acid mine drainage (AMD). In a conventional way of AMD treatment, these pollutants are only removed at higher pH and requires costly alkaline chemicals

A system which harvests thermal energy from various sources such as sunlight, cars, power plants, factories and other industries, and converts it into electricity. The harvested heat energy is stored in a storage tank, with water used as an energy storage medium. This then flows along a gradient to