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Performance of nitrification and denitrification biofilters in a small-scale recirculating aquaculture system
7th International Conference on Aquaculture & Fisheries
October 19-21, 2017 | Rome, Italy

Zipporah Gichana

University of Natural Resources and Life Sciences, Austria

Posters & Accepted Abstracts: J Aquac Res Development


Recirculating aquaculture (RAS) are designed to reduce nitrogenous wastes using nitrification process with limited attention on denitrification, although it is one of the most efficient methods to reduce nitrates in wastewater. Besides denitrification can reduce water usage, orthophosphates, need for aeration and can be applicable in areas with frequent power shortages. This study assessed the efficiency of nitrifying and denitrifying biofilters in a small-scale RAS for Nile tilapia production. The biofilters consisted of a 200 L plastic barrel packed with 50 cm depth of pumice stones with 5.5 L/min flow rate. Preliminary results show an increase in removal of nitrogenous wastes in the two biofilters with increase in time. However, the denitrification biofilter was more efficient (55.4±0.9 %) than the nitrification biofilter (45±1.3%) although endogenous organic carbon was used to fuel the process. A remarkable decrease of ammonia was observed in the two biofilters but nitrates increased with time in the nitrifying biofilter. There was a remarkable difference between the denitrification and nitrification biofilters (P?0.05). The growth of fish was not affected by the performance of the two biofilters (P?0.05); however, the survival rate was higher in the RAS with denitrification biofilter (94%) than in RAS with the nitrification biofilter (88 %). In conclusion, denitrification can be a feasible and cost-effective method to reduce nitrogenous wastes from aquaculture and it can replace nitrification biofilters since ammonia can be oxidized anaerobically by anaerobic ammonium oxidation (Anammox) bacteria.