Preliminary Study On Enhanced Nitrification Performance And Influence Factors Using Electro-Biological Contractor

In recalculating aquaculture system (RAS), the ammonia in the water is toxic to fish, biological filter is a common method for the removal of ammonia nitrogen. However, the traditional methods have the limits in saving energy, and increasing the reaction efficiency. Bio-electric reactors (BER), especially the study in simultaneous nitrification and denitrification (SND) provide some new ideas for the application of water treatment technologies which combine the electro-chemical technology and biological membrane technology, and it is especially valuable for the emergency treatment in the RAS.This paper mainly studied the nitrification and its dynamics kinetics under different voltage in the series rotating biological contactor reactor, and the compartmental kinetics characteristics of nitrification under various voltage was studied. The effect and the Current Intensity, the concentration of ammonia nitrogen (TAN) and hydraulic retention time (HRT) on the removal rate of ammonia nitrogen (TAN removal efficiency) also were studied by the method of central composite design(CCD) and response surface analysis. The results are as follows:(1) There is a linear relation between nitrification rate and the influent ammonia load. When the applied voltage is different, the linear equation is different. When the influent ammonia load is low, the effect of voltage was not significant on the nitration reaction rate, when the influent ammonia load increases, the difference effect of voltage on nitrification rate is larger.(2) The kinetic model of nitrification is not the same under different voltages. When the applied voltage was OV (traditional biological filter),1V,3V and5V, the kinetic model of nitrification were R=2.62(S-0.38)/(S+9.10),R=3.17(S-0.18)/(S+8.84), R=3.28(S-0.13)/(S+4.62), R=2.70(S-0.23)/(S+3.48).(3) The nitration piecewise dynamic model keeps a grade order nitrification under different applied voltage in the condition of low concentration of ammonia nitrogen, but gradually into the half grade or zero order kinetics reaction kinetics reaction with the increase of concentration of ammonia nitrogen. And one of the conditions of3v it into half level dynamics and zero order kinetics reaction of ammonia nitrogen are less than the other conditions, to prove its higher removal efficiency of ammonia nitrogen under the same concentration of ammonia nitrogen.(4) The results showed that the nitrification could be easier to become half-order and zero-order kinetic rate under the condition of3v than others because it had smaller range of first-order nitrification, which means higher nitrification rate. This could be useful when there is an emergency in RAS.(5) Response surface analysis test for the ammonia nitrogen concentration and hydraulic retention time on ammonia nitrogen removal efficiency were different significantly, and the best current intensity was1.1±0.1A/m2.(6) Coulomb Efficiency is different under the different conditions. Besides, the highest columbic efficiency showed up under the condition of1A/m2for current density,12.38h for HRT,8.29mg/L for TAN.This study shows that the ability of the nitration reaction would enhance the nitrification, but the intensity of electric current have to be controlled within a certain range of security.