Improving Biological Treatment of Drinking Water

In Denmark, drinking water is not disinfected with chemicals such as chlorine, which makes the product water sustainable, environmentally friendly, and safe for the consumer. Thus, as no disinfection is used, unwanted microbial growth in the water distribution system needs to be controlled by keeping nutrient concentrations during distribution low. Ammonium (NH4 +) is one nutrient of concern, and is typically removed in biologically active sand filters, during water treatment. The removal process is called nitrification, conducted by microorganisms which need nutrients to metabolize the NH4 +. Hence, if nutrients are already too low during treatment, NH4 + removal can be incomplete, subsequently endangering water quality during distribution. The aim of this project was to investigate if addition of selected nutrients to biological sand filter columns could improve biological NH4 + removal from drinking water.