The Methanogenesis Kinetics Of Granular Sludge From EGSB Reactor And The Inhibition Of NO₂ On It

It is popular to study the nitrogen removal methods in recent years. It also has been reported that NO₂ is significant essential for anaerobic ammonium oxidation. So the effects of NO₂ on the integration of anaerobic methanogenesis and denitrification with anaerobic ammonium oxidation should be further researched. Therefore, the experiments without and with trace NO₂ have been studied on the granule sludge from the EGSB reactor in which the integration of anaerobic methanogenesis and denitrification with anaerobic ammonium oxidation has been finished. The paper established the reaction kinetic equation of the anaerobic methanogenesis and the inhibition kinetic equation of NO₂. The influences of NO₂ on the anaerobic methanogenesis also was discussed. The results indicated:â‘ In the absence of NO₂, methanogenesis kinetic experiments showed that the relationship between specific substrate detradation rates and substrate concentrations accord with Monod equation.The kinetics of methanogenesis have been analyzed and kinetics parameters have been got: Vmax=0.158h^-1, Ks=464.27mg/L, y=0.254ml/mg.â‘¡The trace NO₂ would inhibit the substrate degradation and the inhibition degree would increase with the trace NO₂ concentration increasing.15ppm,25ppm,50ppm,100ppm and 150ppm NO₂ resulted in 7.40%,11.87%,27.56%,39.75% and 43.24% inhibition, respectively. The CI50 of trace NO₂ to the methanogenic bacteria was 205ppm(4.149×10^-4mg/L).The specific substrate degradation rate equation with the trace NO₂ have been established:â‘¢NO was monitored present in the outlet flow by the NO₂/NO instrument. The NO₂ and NO concentration in the outlet flow was about 10.3%-49.4% of the NO₂ concentration in the inlet flow.And most of nitrogen couldn't be monitored, it is likely due to that part NO₂ was translated into nitrite and nitrate, nitrite into NO and nitrate, and at the same time nitrite and nitrate into N₂ by denitrification. Furthermore, the operation and the gas collecting process would also arose subjective losses.â‘£The trace NO₂ would inhibit the anaerobic methanogenesis, for the biochemical actions of methanogenic bacteria were affected by the factors that the trace NO₂ could...