| ANAMMOX process for the treatment of nitrogen has some general cost-efficient advantages compared to nitrification-denitrification. The ideal process features autotrophic conversions of ammonium and nitrite to dinitrogen gas without demand for oxygen and no external carbon requirement. A liquid-solid fluidized bed reactor (FBR) was chose for its low cost and high efficiency in reducing the outer mass-transfer resistance. Moreover, using PVA beads which is light and easy to suspend in water, has the characteristics of highly effective, stable, energy conservation, and so on.Firstly, this paper researched the characters and simulation of denitrogenation by immobilized ANAMMOX sluge in a FBR. Denitrogenation was carried out experimentally, integrated a liquid-solid fluidized bed reactor (FBR), the using of polyvinyl alcohol (PVA) beads as the biocarriers and perfect ANAMMOX process. The conclusions are as followed:(1) The experiment carried out in this paper is exactly the ANAMMOX process.Ratios of T-N removal, NO2--N removal, and NO3--N production to NH4--N removal were 1.86:1.02: 0.16. The color of the PVA-gel beads changed from white to brownish red, which is consistent with ANAMMOX bacteria. By the Denaturing Gradient Gel Electrophoresis (DGGE) method, both KSU-1 and KU-2 anammox strains were detected with KSU-1 in dominance in the FBR process.(2) This process can achieve a satisfactory efficiency in denitrogenation. With hydraulic retention times(HRTs) from 16 h to 9 h , NH4+-N and NO2--N removal efficiencies were about 81% and 92%, respectively. The removal rates of NH4+-N,NO2-N and total nitrogen increased up to 0.71 kg N/(m3·d), 0.77 kg N/(m3·d)and 1.35 kg N/(m3·d), respectively.(3) Compare to other types of bioreactor, FBR using PVA as carrier can get more stable and higher abilities in not only NH4+-N removal and NO2--N removal.In addition, a mathematical model was formed using both bioreaction engineering principles and artifical neutral network. The conclusions are as followed:(1) Overall effectiveness factors (ηDf) demonstrating the internal and outer mass-transfer resistance approximated 100% corresponding with bulk concentration. This indicated that mass-transfer resistance could be neglected for the low growth rate of ANAMMOX bacteria. (2) The simulated results corresponded satisfactorily with the experimental data.It was the first time that, a mathematical model about two substrates was used to describe the simultaneous diffusion and reaction of substrate in the FBR. Not only the internal and outer mass-transfer resistance, but also the character of the Bioreaction Dynamics and the growing mode of biofilm were considered. Moreover, the proposal model also takes account of the detachment of the biofilms and therefore it can predict both the concentration of substrates and density of alive biofilms in all parts of the FBR.Results from this paper can also provide provide scientific basis for industrial application of the denitrogenation by immobilized ANAMMOX sluge in a FBR.
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