Nitrification performance of sand, polystyrene microbead and Kaldnes® bead in relation to ammonia loading rate

Abstract

The volumetric TAN removal rate increased with increasing ammonia loading rate in all filter media. Mean volumetric TAN removal rates at 5, 25, and 50 g m-3 d-1 in SF (39.3, 168.6, and 322.7 g m-3 d-1, respectively) were higher than those of PF (35.0, 157.4, and 310.5 g m-3 d-1, respectively) and KF (32.1, 142.5, and 288.1 g m-3 d-1, respectively). These results are due to the differences of SSA among the filter media. However, sand need high energy requirements to lift up sand in the biofilter and induce increased energy cost and Kaldnes® showed lowest ammonia removal efficiency and the highest price per media, it also increases cost. Removal of TAN of SF was observed superior and showed the highest SSA. However, sand need high energy requirements for lift up and fluidizing sand bed in biofilter and result in increasing of energy cost. On other hand, the performance of polystyrene and Kaldnes® media werealso satisfactory in terms of maintaining the water quality and because both media are light, the methods of down flow filtering (trickling) is applicable. Therefore, energy cost might be much lower than fluidized SF. According to above analyzed results, polystyrene is recommended owing to their good performance in ammonia removal, light in media weight and more economical per volume of surface area.