Survey of nitrification dynamic and rules of different biofilteration process in aerobic biofilters

Nitrification rate of biofilters is influenced by ammonia concentration and levels of ammonia vary in response to feeding time. On the other hand, existence and activity of different groups of bacteria can be expected in the biofilters. Hence in this research, nitrification dynamic of biofilters during day hours and also rules of different biofilteration process (nitrification, denitrification and anamox) in aerobic biofilters of Common carp recirculating aquaculture system were surveyed. To conduct of this research 12 pilot recirculating aquaculture systems with barley straw, wood chip, sponge and PVC pure pipe based biofilters were designed. After activation of biofilters, nitrification rates measured at day 46 and 61 in 4 hour interval and via sampling of granules from biofilters at day 62, nitrification, denitrification and anamox process were surveyed. Results indicated that nitrification rates were different during day hours, as so peak rates observed in related to feeding time. Nitrification rates in batch culture of granules were greater than maximum rates obtained for biofilters established in recirculating aquaculture systems and these granules showed not only nitrification but also denitrification and relatively anamox activities. In conclude by modifying the management of biobilters all biofilteration process of inorganic nitrogen wastes can be useful.