Use of natural zeolite to enhance nitrification in biofilter.

To enhance nitrification, natural zeolite and activated carbon were tested as a media in a biofilter to treat wastewater containing relatively high concentrations of TKN. Using those media, the adsorption isotherms for ammonium ion were compared; the K values for natural zeolite and activated carbon were found to be 0.5117 and 0.0006, respectively. In comparison of the performance of the two media, two identical, lab-scale biofilters were then operated for 4 months. The effect of NH3-N loading rates on the performance was investigated. The results showed that higher NH3-N removal efficiency and faster nitrification were achieved in the biofilter with natural zeolite throughout the experimental period. Nitrosomonas and Nitrobacter, two principal nitrifiers, in biofilm grown on two different media were counted and compared. Nitrobacter which is the more fragile of the two principal nitrifiers was outgrown in the biofilm on natural zeolite media. The reason for this may be due to the ammonium ion exchanging capacity of natural zeolite which provided the favorable environment for Nitrobacter.