KVÄVEMUREN I HELSINGBORG – ERFARENHETER FRÅN ANLÄGGNING, FÄLTMÄTNING OCH LABORATORIEFÖRSÖK / The denitrification wall in Helsingborg – experiences from construction, field experiments and laboratory experiments
This is an evaluation of a new method, the denitrification wall, with the purpose of diminishing nutrient content in drainage water from agriculture land use. The denitrification wall consists of a trench filled with soil mixed with sawdust that intersects the drainage pipes.. The concept was applied in the drainage area of River Råån in southern Sweden. Nutrient reduction and technical function were studied in field and laboratory experiments. The field experiment showed a reduction of total phosphorous of 67 % and orthophosphate of 79 %. The reduction of total nitrogen was 9,3 % and nitrate + nitrite 9,2 %. Laboratory experiments indicated higher denitrification activity initially in straw compared to sawdust. After a period of incubation, sawdust also had high denitrification activity. After a long incubation period, a mixture with straw and soil showed high mobilisation of ammonium, which was not observed for a sawdust mixture. The results indicated high nutrient reduction potential, which makes the method interesting for other uses such as treatment of sewage water in non urban areas and from greenhouses. Another possible application is to use the denitrification wall in com-bination with constructed ponds and wetlands.