EFFICIENCY OF NITRIFICATION IN TRICKLING FILTERS USING DIFFERENT FILTER MEDIA

O.I. Lekang, H. Kleppe-2000

Aquacultural Engineering, 21 (3): 181-199 (from Current Contents)

Abstract :

The efficiency of nitrifying trickling filters varies with media type. Three sizes of crushed Leca (dried expanded clay) and three types of plastic media (Kaldnes rings, Norton rings, and a rolled mat of Finturf artificial grass) were tested in columns 1.5 m high and 11 cm in diameter. Synthetic water containing 1.5 mg total ammonia nitrogen (TAN)/l and 1 mg PO43-/1 was added at a rate of 0.5 1/min and a temperature of 15 C. The nitrification rate stabilised 7-8 weeks after start-up in the Leca fractions and artificial grass columns. For the other two media, no positive stabilization was observed over the duration of the experiment (140 days). At the end of the experimental period, the nitrification rate was 100% in the Leca fraction columns, 80% in the Kaldnes ring columns, 60% in the Norton ring columns and 40% in the artificial grass columns. The nitrification rate was between 0.1 and 0.2 g TAN/m/day in the different columns, and the hydraulic load was below 0.25 m^3/m^2/day.

(Univ Agr, Dept Agr Engn, Pb 5065, N-1430 Aas, Norway, e-mail: odd-ivar.lekang@itf.nlh.no)

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