Nitrogen elimination from landfill leachates using an extra carbon source in subsurface flow constructed wetlands

• Published in: Water science and technology Vol. 56; no. 3; pp. 125 - 133
• Main Authors: Rustige, H, Nolde, E
• Format: Journal Article
• Language: English
• Published: England IWA Publishing 01.01.2007
• Subjects: Acetic Acid; Activated carbon; Advection; Artificial wetlands; Beds; Carbon sources; Denitrification; Design optimization; Environmental monitoring; Filtration; Flow system; Kinetics; Landfill; Landfill construction; Landfills; Leachates; Nitrification; Nitrogen; Nitrogen - isolation & purification; Nitrogen removal; Pilot Projects; Plants; Reed beds; Reedbeds; Removal; Sand; Sand filters; Silicon Dioxide; Vertical flow; Vertical mixing; Waste disposal sites; Waste Disposal, Fluid - methods; Water Movements; Water Pollutants, Chemical - chemistry; Water Purification - methods; Wetlands
• ISBN: 9781843395980; 1843395983
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2007.506

A three-stage constructed wetland for leachate treatment was monitored on a landfill at a pilot scale. The plant had been designed to achieve at least 75% nitrogen removal. NH4-N input concentration was 240 (median) up to 290 mgl(-1) and COD concentration was 455 to 511 mgl(-1), respectively. A 14 m2 vertical flow sand filter plus a 14 m2 horizontal flow sand filter followed by a 3.3 m2 vertical flow sand filter was chosen. Acetic acid was added to the horizontal flow system for denitrification. The results showed a very stable nitrification rate within the vertical flow system of 94% (median) at NH4-N loading rates of about 10 (median) up to 17 gm(-2)d(-1). Denitrification was mainly dependent on the dosing of acetic acid and could reach a maximum of 98%. One interesting effect was the production of nitrite in the horizontal flow sand filter. This could efficiently be eliminated by the subsequent vertical flow sand filter. The chosen concept proved to be very effective for nitrogen removal. In combination with a final activated carbon filter the COD effluent concentrations could be easily and safely controlled. The design of denitrification reed beds showed a further potential for optimization.