Transformation and removal of nitrogen in reactive bed filter materials designed for on-site wastewater treatment

• Nitrogen (N) and phosphorus (P) should be removed and recycled from wastewater in order to reduce the nutrient load to recipient waters, avoid contamination of groundwater and conserve resources. Nitrogen removal and transformation were studied in domestic wastewater percolating in unsaturated conditions through 0.5 m long columns containing potential filter materials. Six materials (three types of slag, limestone, opoka, Polonite(R) and sand) were compared at a design loading rate of 85 L m(-2) d(-1) during 67 weeks. All materials transformed ammonium efficiently to nitrate (>98%). Apparent removal of inorganic N was shown only by the coarsest slag and by Polonite(R), possibly due to losses through volatilisation. All other filter materials leached nitrate at the column effluent. Total N content was highest in the surface layer of the column material, with decreasing values with depth. In contrast, carbon

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Naturresursteknik -- Annan naturresursteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Engineering -- Other Environmental Engineering (hsv//eng)

Keyword

Ammonium removal

Blast furnace slag

Column experiment

Nitrification

Polonite (R)

flow constructed wetlands

phosphorus retention

ammonium removal

ion-exchange

sand-filters

subsurface flow

shell sand

denitrification

performance

effluent

Environmental engineering

Miljöteknik

Publication and Content Type

ref (subject category)

art (subject category)