Manganese removal using an aerated granular filter

Experiments on manganese removal using an aerated granular filter with mean particle size of 3.68 mm and 5.21 mm anthracite were conducted at a filtration rate of 100 m d^-1. Air, with a rate of 0 to 366 m d^-1, was supplied through nozzles positioned 100 mm above the filter column bottom. From the experiments that were conducted, it was found that manganese removal is completed at a pH of 9.6 or above. In addition, the oxidation and removal rate of dissolved manganese were expressed as a first-order reaction. The smaller the filter media particles were, the higher the manganese removal efficiency was. The aeration rate of dissolved oxygen in raw water is sufficient for the manganese removal process. The manganese removal rate increased with time due to the catalytic effect of manganese dioxide (MnO₂) attached to the media. The x-ray diffraction analysis showed that the solids attached to the filter media were not crystalline but amorphous manganese.