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SIMULATION MODEL FOR DESIGN AND MANAGEMENT OF WATER RECIRCULATING SYSTEMS IN AQUACULTURE

SIMULATION MODEL FOR DESIGN AND MANAGEMENT OF WATER RECIRCULATING SYSTEMS IN AQUACULTURE

Added by: elsayed.khater
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A simulation model for design and management of water recirculating aquaculture systems was developed. The model is able to predict the water temperature and energy consumption at different air ambient temperature (23, 25, 27, 29 and 31 ºC) and to predict the oxygen consumption, ammonia production and nitrate production at different water temperatures (24, 26, 28, 30 and 32 ºC). Also, the model is able to predict the solids generation at different water depths (0.8, 1.0, 1.2, 1.4 and 1.6m) and different settling velocities (1.25, 1.67, 2.08, 2.5 and 2.9 m/h). Experiment was carried out to validate the model results which include: water temperature, dissolved oxygen, ammonia, nitrite, nitrate, solids, pH, alkalinity and fish mass. The results indicated that the average hourly temperature predicted by the model was in a good agreement with those measured by the system, where, it ranged 25.00 to 30.90˚C experimentally, while it was from 24.20 to 29.86˚C theoretically. The predicted oxygen consumption values were in the range 189.13 to 457.56 mg O2/kg fish per hour and the measured oxygen consumption values were from 197.42 to 467.61 mg O2/kg fish per hour. The ammonia production from the system ranged from 10.56 to 52.96 mg NH3/kg fish.hour experimentally while it was from 10.45 to 48.61 mg NH3/kg fish.hour theoretically. The nitrate XXIII production in the system ranged from 41.61 to 222.31 mg NO3/kg fish.hour experimentally, while it was from 45.34 to 210.97 mg NO3/kg fish.hour theoretically. The efficiency of the biological filter for ammonia removal from the system ranged from 11.11 to 63.64 %. The settleabe solids removal was determined and was found to be between 0.0304 to 0.0556 kg m-3 (30.40 to 55.60 mg l-1) while it was 0.039 kg m-3 (39 mg l-1) theoretically. The suspended solids removal was found to be between 0.0123 to 0.0806 kg m-3 (12.30 to 80.60 mg l-1) while it was from 0.0124 to 0.1425 kg m-3 theoretically. The hydrocyclone and screen filter efficiency to remove the solids from the system ranged from 27.4 to 57.79 % and15.46 to 74.41 %, respectively. The daily average fish growth rate from the system ranged from 0.26 to 1.46 g/day experimentally, while it was from 0.11 to 1.96 g/day theoretically. The weight of individual fish from the system ranged from 4.00 to 115.79 g experimentally, while it was from 4.00 to 130.80 g theoretically. The feed conversion rate ranged from 0.61 to 2.25 kg feed / kg fish actually, while, it was estimated to be from 0.50 to 1.94 kg feed / kg fish theoretically. The actual and theoretically energy consumption by whole system during the whole day was 377252.50 and 359896.5 kJ.day, respectively. The model results were in a reasonable agreement with the experimental ones.

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