Efficiency of sand, polystyrene microbead and Kaldnes® bead for red seabream culture in laboratory scale recirculating system

Abstract

The volumetric total ammonia nitrogen (TAN) removal rates for SF, PF and KF were 193.8, 183.9 and 142.6 g m-3 d-1, respectively and the volumetric NO2-N removal rate for SF, PF and KF were 113.4, 105.9 and 85.8 g m-3 d-1, respectively. The TAN and NO2-N removal rates of KF were lower than those of SF and PF (P<0.05), but there were no significantly differences between SF and PF (P>0.05). The concentration of total suspended solid decreased in KF and increased in SF and PF. Weight gain, specific growth rate and feed conversion efficiency of KF were lower than those of SF and PF (P<0.05), but there were no significantly differences between SF and PF (P>0.05). The volumetric TAN removal rate of SF was the highest and SF also has the highest SSA. However, SF needs high energy requirements for lift up and fluidizing SF in biofilter and that induced increasing of energy cost. Meanwhile, the performance of PF and KF was also satisfactory in terms of maintaining the water quality. Both media are light, the method of down flow filtering (trickling) is applicable. Therefore, energy cost might be much lower than fluidized SF. Based on the analyzed results above and since the red seabream could grow within acceptable range in three biofilter system, PF is recommended due to their good performance in ammonia removal, light media weight and more economical.