Chemical Phosphorus Removal from Onsite Generated Wastewater

Phosphorus originating from onsite generated wastewater is becoming recognized as a major cause of impairment to streams and lakes. Efficient, low maintenance technologies are needed to reduce discharge levels. Removing phosphorus using luxury uptake or precipitation followed by settling, as is common at municipal wastewater treatment plants, is not practical for onsite generated wastewater. Alternatives include reactive media that remove phosphorus by ion exchange and/or surface precipitation. Various media have been studied, ranging from natural to highly manufactured. This ongoing research examined 3 types of media. Included were a ceramic foam manufactured from waste iron hydroxide-coated iron and the same foam coated with a nano enhanced iron hydroxide. Additionally, a commercially available activated aluminum product was tested. All of the media worked relatively well during continuous labscale column studies that employed effluent from a recirculating sand filter. The iron media had a distinctly different phosphorus removal pattern than the activated aluminum. A linear scale-up of the best performing column run found that 3.4 ft3 of media would be needed every 3 months to reduce the phosphorous level down to 2 mg/L P in a typical single-family 500 gal/day system. Testing is ongoing with a new generation of both types of products, as well as the use of the exhausted media for beneficial purposes.