Direct Biofiltration for Manganese Removal from Surface Water

Research has shown biological filtration to be a successful treatment for the removal of manganese (Mn) from groundwater and surface water. In this study, bench-scale direct biofiltration was used to remove Mn and dissolved organic carbon (DOC) from a pH 6 surface water source in Halifax, Nova Scotia, Canada. Three factors were examined for their effects on Mn and DOC removal: media type (granular activated carbon and anthracite), pH (6 and 9–11), and nutrient enhancement with phosphorus (P; 20 and 200 μg/L). pH was a significant factor in Mn removal (α=0.05). The P-enhanced pH 6 biofilters for both media obtained an average 91% Mn removal; the P-enhanced pH 9–11 filters for both media achieved an average 70% Mn removal. An average of 23% DOC removal was achieved with P enhancement, compared to 12% DOC removal without P enhancement. Mn was likely removed by biological oxidation and biogenic oxide adsorption. These results show that direct biofiltration of raw surface water at pH 6 can remove Mn t...