Model experiments on improving nitrogen removal in laboratory scale subsurface constructed wetlands by enhancing the anaerobic ammonia oxidation.
Anaerobic ammonia oxidation (Anammox) has been identified as a new general process-strategy for nitrogen removal in wastewater treatment. In order to evaluate the role and effects of the Anammox process in wetlands, laboratory-scale model experiments were performed with planted fixed bed reactors. A reactor (planted with Juncus effusus) was fed with synthetic wastewater containing 150-200 mg L(-1) NH4+ and 75-480 mg L(-1) NO2(-). Under these operating conditions, the plants were affected by the high ammonia and nitrite concentrations and the nitrogen removal rate fell within the same range of 45-49 mg N d(-1) (equivalent to 0.64-0.70 g Nm(-2)d(-1)) as already reported by other authors. In order to stimulate the rate of nitrogen conversion, the planted reactor was inoculated with Anammox biomass. As a result, the rate of nitrogen removal was increased 4-5-fold and the toxic effects on the plants also disappeared. The results show that, in principle, subsurface flow wetlands can also function as an "Anammox bioreactor". However, the design of a complete process for the treatment of waters with a high ammonia load and, in particular, the realisation of simple technical solutions for partial nitrification have still to be developed.
Paredes
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Facultad de Ciencias Ambientales, Universidad Tecnológica de Pereira, Apartado Aereo 97. Sede la Julita, Pereira, Colombia. diparede@utp.edu.co
Kuschk
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Stange
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Müller
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Köser
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D000641:Ammonia / Q000378:metabolism*; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D018533:Biomass; D019149:Bioreactors; D009584:Nitrogen / Q000302:isolation & purification*; D010084:Oxidation-Reduction; D012106:Research; D014865:Waste Disposal, Fluid / Q000379:methods; D018508:Water Purification / Q000379:methods*; D053833:Wetlands