A feasibility study of using hematite to remove dissolved organic carbon in water treatment

An experimental investigation of using hematite to remove natural organic s ubstances from water was carried out. Hematite sols (iron oxide, alpha -Fe2 O3) prepared in the laboratory were found to form flocs with natural organi c substances. Jar tests revealed that when a 85 mg/L hematite concentration (as Fe) was used, natural organic substances in the form of fulvic acid (4 mg/L) were totally removed. Direct filtration experiments using hematite w ere effective in removing dissolved organic carbon (DOC) from water; howeve r the large hematite-organic flocs clogged the filter and reduced the filte r run. A conventional filtration system, which included flocculation and sedimenta tion prior to filtration, was found to be very effective at removing total DOC from water. An 86 mg/L hematite concentration (as Fe) was found to effe ctively remove 4 mg/L of fulvic acid from Milli-Q water. A residual iron co ncentration in the final effluent from the filtration unit was well below t he allowable Australian drinking water guideline. Further research is warra nted to optimize hematite concentration, pH, and ionic strength for applica tion of this process in conventional water treatment plants.