Substantiation of the calculation methods of the nitrogen removing (nitrification) in bioreactors with using on the biofilm models

Abstract

The mathematic model and calculations of the waste waters cleaning parameters from the compounds ammonium nitrogen (nitrification) in bioreactors with additional using in theirs volume the fixed biocenosis as the biofilm are presented. The valuation of the different influence factors on the waste waters cleaning parameters is given. The kinetics of reaction according to Monod nonlinear equation is used that allow to calculate the nitrogen concentrations on the external and in the interior biofilm surfaces and to evaluate the efficiency of the biofilm work of the given thickness relative to penetration character of the nitrogen pollutions in it. As showed the biofilm thickness and the flow in it are decreasing as the tearing off velocity of the biomass from its surface is increasing where as at increasing of the nitrogen concentrations these parameters are increasing. At this the substrate flow and the penetration depth into the biofilm are the functions of the substrate concentration on the biofilm surface, velocity of the reaction within it and the diffusive masstransfer. As a main parameter for evaluation of the oxygen influence for control of the process of ammonium oxidation to nitrite the relation of the concentrations oxygen to ammonium nitrogen is proposed. The specific examples and calculations have showed the given relation may be better alternative for control of the nitrification processes in reactor in comparison with oxygen concentration.