INVESTIGATION OF BIOLOGICAL FILTRATION FOR REMOVAL OF MANGANESE FROM DRINKING WATER

Abstract

Reduced iron and manganese in drinking water can cause aesthetic concerns and manganese has potential neurotoxic effects. Biofiltration is a proven but poorly understood method for removal of manganese from drinking water. In this research media selection for biofiltration is investigated in bench-top and pilot-scale experiments. Treatments using sand as filter media had higher rates of manganese removal, and pilot-scale sand filters supported 36,666 and 25,000 colony forming units per gram (CFU/g) of media while anthracite and recycled glass supported 11,111 and 6,349 CFU/g of media, respectively. Biological filtration proved to be an effective treatment option for removal of iron and manganese for the municipality where it was piloted. Sand filter removal rates ranged from 88.0% to 91.9% for iron and 84.3% to 87% for manganese. Canadian Drinking Water Quality Guidelines (CDWQG) were met for 44 of 44 samples for iron and for 35 of 44 samples for manganese. Deoxyribonucleic acid (DNA) sequencing indicated that manganese oxidising bacteria (MOB) accounted for 4.0% of total bacteria and that 10 phyla made up 95.5% of the bacteria in all filter samples.