NOM removal by slow sand filtration through iron oxide-coated olivine

摘要

A 16-month pilot study compared iron oxide-coated olivine (IOCO) with uncoated olivine and plain sand as a medium for slow sand filtration. Three columns, each containing one of the media, were fed water from one proposed and one existing water supply source, and the removal efficiencies of natural organic matter (NOM) in the columns were compared. Consistent with previous work, NOM removal (measured as dissolved organic carbon or UV_(254)) was slight in both the sand-packed and olivine-packed columns. However, removal of NOM was dramatically better in the IOCO-packed column. This improved performance could be attributed to both more efficient adsorptive removal of NOM and greater bioactivity in the IOCO column. During the test period, there was no indication that the adsorptive capacity of the IOCO was approaching exhaustion, suggesting that the adsorption sites were being bioregenerated. The performance of the IOCO warrants further evaluation as a technique for removing disinfection by-product precursors, particularly in small systems.