Industrial wastewaters is the manufacturing wastewater includes many kinds of wastewater from candy, paint, wine and beer, soft drink, automobile, textile, aquatic products processing factories, aquaculture (especially hatchery)... In this study, concentrate on the kind of aquaculture seed (hatchery) wastewater, and modelisation and simulation of this treatment process by MBBR. The idea technique to removal nitrogen is MBBR with the high efficiency and the simple in the capital and save the volume of the aerobic tanks by the useful and large specific area of the media about 8.000 10.000 m2/m3 that helps the growth of slowly growing bacteria such as the nitrifiers and denitrifiers. All these processes have been modelized and simulated by a modified ASM3 model, named ASM3_2step_MBBR. The model takes into account the presence of the microorganism in the bulk of the liquid and in the fixed bio-film as well. Kinetic and stoichiometric parameters (u_A_NH, Y_A_NH
Y_A_NO2, Y_H_O2, b_A, KA_NH), were determined from biokinetic tests and respirometry. Simulation yielded high potential removal rates of nitrification is less than lkg-Ni11media/3day. After validation, currently, the pilot plan is also the aim of this study to compare with the result from modelisation to validate the parameters in the ASM3_2step_MBBR.