Study On Internal Loop Fixed Bed Biofilm Reactor Behavior For The Treatment Of Wastewater

The treatment of wastewater by using biofilm method is simple and highly effective technology. Compared with the activated sludge process, the biofilm technology has many advantages such as higher removal efficiency, less equipment, smaller layout area, wide application, strong impact resistance and stable ecological system in reactors and so on.The paper reasearches and develops a new type of reactor that combines the structural characteristics of Airlift Internal Loop Reactor with the elasticity plastic biofilm carrier. The reactor not only utilizes fully the advantages of technology of biofilm wastewater treatment, but also has a good hydrodynamics condition because of the internal loop flow pattern inside the reactor. The experimental set-up of the new type of reactor, which is named Internal Loop Fixed Bed Biofilm Reactor (ILFBBR), is built and investigated.The paper studies the effect of biofilm formation process in ILFBBR by using the synthetic wastewater. It also studies the treatment effect and influencing factors in C/N removal rate. In addition, the kinetics of substrate degradation is calculated by utilizing the method of the numerical simulation. The main contents of the dissertation are as follows:1. The experimental set-up of ILFBBR is built, and the formation process of biofilm on the carrier is investigated.2. The optimal operating parameters and influencing factors of removal rates of COD and nitrogen are confirmed. The function of simultaneous nitrification and denitrification in the reactor is achieved.3. Compared with activated sludge reactor and fluidized bed bio-reactor, ILFBBR shows higher removal efficiency of COD and NH4-N. Furthermore, it has also some advantages such as non-recirculating external flow, smaller gas/liquid ratio and lower operating cost.4. The parameters in kinetics equation of substrate degradation are determined by using the method of nonlinear least squares and error analysis. These parameters are as follows:μ_max/Y_X/S=0.0156 min^-1,K_s=516.96 mg.L^-1,K_i=697.57 mg.L^-1,k_e/Y_X/S=0.0022 min^-1.The simulation results show that it is appropriate in describing the behaviour of kinetics of substrate degradation by using the equation of Haldane-Endo that is developed in this paper.