Influence of nutrient supplementation on DOC removal in drinking water biofilters

Analysis of the impacts of nitrogen, phosphorus and potassium supplementation on biofilter performance for organic carbon removal was studied on laboratory-scale biofilter columns. Three dual media biofilter columns were fed with synthetic raw water C:N:P ratios of 546:24:1, 100:10:1, and 25:5:1 (w/w) to simulate nutrient limited and two nutrient supplemented conditions, respectively. Research found that air-scour versus water only backwash improved the nutrient limited dissolved organic carbon (DOC) removal by 8%. In addition, nutrient supplementation and backwash alteration improved DOC removals by 19% for the 25:5:1 column and 14% for the 100:10:1 column. Potassium supplementation with the 25:5:1 C:N:P ratio column had no discernible effect on DOC removal. No correlation with phospholipid (7–474 nmol P/g media) and adenosine triphosphate (ATP) (0.6 × 10⁵–32.74 × 10⁵ pg ATP/g media) values with DOC removal were found. Nutrient availability was found to influence DOC removal, demonstrating its importance when utilizing biofiltration for treatment of source waters.