Mathematical model for goldfish recirculating aquaculture system (GRAS)

摘要

A mathematical model is framed for a goldfish recirculating aquaculture system based on unsteady-state mass balance for prediction of the concentration of total ammonia nitrogen (TAN), nitrite-nitrogen (NO2-N), nitrate-nitrogen (NO3-N), dissolved oxygen (DO) and total suspended solids (TSS). The goldfish were stocked at 100 numbers per m(3) of rearing water volume of 5 m(3) tank capacity in the years 2009 and 2010 and the model was calibrated and validated. The recirculation flow rate was fixed at 29,000 L/day. The model parameters were estimated as k(TAN) (mg of TAN generated per kg of feed): 20,000, M (mortality rate): 0.002 day(-1), alpha (percentage of feed conversion to suspended solids): 23.8, k(oxy) (mg of oxygen required for fish respiration per kg of feed applied in unit time): 300,000, k(b) (partial nitrification in the culture tank): 0.86 and the reaction rate constants, k(1) and k(2) : 84.65 day(-1) and 42.03 day(-1) respectively and temperature growth coefficient (TGC): 5.00 x 10(-5). The model efficacy was adjudged by estimation of the coefficient of determination (R-2), root mean square error (RMSE), Nash-Sutcliffe modelling efficiency (E-NS) and graphical plots between predicted and observed values.