A Mathematical Model Of Inhibited Aerobic Biofilm And Simulation

The coking wastewater is difficult to dispose, which contains wide range of contaminants. In this paper, we studied the process of an A/O biofilm reactor, some simplifications had been implemented at the base of the activate sludge model No1 (ASM NO.1), an inhibited aerobic biofilm model was established through combing the feature of the coking wasterwater and the theory of convection and reaction. A computer program was developed to model and simulate the result of the operation with a Matlab's tool. The model was applied to forecast the situation that the Biological aerated filters (BAF).In this study, I decided to applied A/O biofilm systems to deal with the coking wastewater, COD in the purified wastewater has reached the second class of integrated wastewater discharge standard. According to the wide pH range in the coking wastewater, NH₄⁺-N in the purified wastewater has not below 25mg/L, so in order to have better removal efficiencies, the pH in the BAF should more than 7.5. And there should be pretreatment equipments in order to reduce the SS and coking oil in the influent water when we apply A/O biofilm systems to deal with the coking wastewater. It can reduce the toxicity of the coking wastewater to dilute the purified wastewater from the AF, so the systems can have the better removal efficiencies. Because COD and NH₄^-N load in the influent water have a great influence on the nitration reaction ,the systems should remain the steady influent COD and NH₄⁺-N load.The inhibited aerobic biofilm model is used to simulate the results of the BAF dealing with the coking wastewater with a Matlab's tool. It provides some valuable reference data for designation, operation and management of diversified biofilm reactors. Some problems which should be solved in the future are brought forward in the paper. Operation parameters and environment factors are studied through the simulation of the program. The results show that high levels of hydroxybenzene could inhibit the activation of microorganism and lead to reducing the removal efficiencies. It is suggested that extractione quipments should be set up before the biochemical treatment to reduce the concentration of hydroxybenzene. Biofilm detachment is the most important factor that influence on the morphology, stability and structure of biofilm. The high detachment velocity would reduce stability of biofilm so that the removal efficiencies would be played down. Lower temperature has great affection on nitration reaction. The better removal efficiencies can be arrived when the biofilm become more thick. The increasing of the COD and NH_<sup>+4-N load is good for the growing of microorganism. So it is also good for the forming of biofilm, but the removal efficiencies of NH₄⁺-N is reduced.