Biological Properties Of Material And Structure Of Suspended Bio-carriers And Cage-type Bioreactor

The rivers are polluted severely, and are cried for treatment. The research on new treatment technology and new devices is one of the most important and hot problem in environment engineering. In this dissertation, the interdisciplinary method with material machining is applied, from study on the biological properties of bio-carriers'material and structure to construction of high-efficiency sewage treatment environment, which is cage-type bioreactor, the new sewage treatment material and high-efficiency sewage treatment devices are provided. Through large numbers of experiments, analysis and numerical simulation, the main results and conclusions are as follows:(1) The large numbers of bio-film experiments of bio-carriers are processed, and the biological properties of bio-carriers'material and structure are discussed. The results show that the bio-film properties of bio-carriers are related with main components of bio-carriers materials, material diversity is beneficial for enhance the bio-film properties of bio-carriers, and the moving bed with mixing bio-carriers gets strong effect of sewage treatment. These can provide a reference for mixture using of bio-carriers, enhancing effect of moving bed, material combination in bio-carriers design. The results indicate that the bio-carriers structure need provide high specific surface area for microbe inhabiting region, and multi-connected structure can improve utilization rate of bio-carriers surface, and be beneficial for gas distribution and obtain the suitable surface shear stress. These can improve the bio-carriers bio-film properties. The force under condition of dynamics sewage treatment is described in detail, and the quantity of bio-carriers bio-film is analyzed by using of microbe adhesion kinetics model.(2) The coupling computation of multi-phase and dynamics mesh is realized, and the hydrodynamics characteristics of bio-carriers are numerical simulated, and it is used for evaluating the rationality of bio-carriers structure, and the computation results are positive related with bio-film results of experiment. It is an efficient method for evaluation of bio-carriers space structure and optimization. According to the computation results, a new suspended bio-carriers, whose structure is wire-wound, is designed, and it is used to treat sewage, the experiment results show that the removal rates of COD_Cr and NH3-N are 79.5%, 80.3% respectively under condition of the effective volume with 1.8L, water flow with 30 mL/min, aeration with 0.3 L/min. These results are better than that of multi-face hollow sphere, pall ring, stage ring, bio-ceramic, and it has more stable to shock load.(3) According to the characteristic of rivers pollution control, based on the initiative moving bed concept, the cage-type suspended carriers bioreactor is developed, which constructs high-efficiency environment for rivers sewage treatment. Its mechanism of removing contamination is analyzed, and flow velocity, which just can drive the bioreactor to rotate, is computed. The start-up experiment, operation parameters optimum experiment, and operation experiment are processed, the results show that the cage-type bioreactor can high effective treat sewage. Under the condition that aperture porosity on cage wall is 58%, the length of inside laminae is 35mm, the carriers fill rates is 50%, the hydraulic retention time is 1.2 h, aeration flow is 2.5 m³/h, the sewage flow is 1 m³/h, rotation-cage rotated speed is 1.5 r/min, and the removal rates of COD_Cr and NH₃-N are 86.9% and 87.6% respectively. Comparing with biological aerated filter and moving bed, it can get high effect.(4) The sewage treatment mechanism of cage-type bioreactor is studied in depth, according to the Monod equation, the kinetics equations of and biodegradation are deducted. The reaction rates constants are obtained by kinetics experiment, and the influence of different bio-carriers is discussed. The preliminary design model of cage-type bioreactors is derived from material balance principles, and the model constants are obtained by experiments. This model is validated by experiment, and the errors are less than 15%, these models are reference for enlarged design and practical application of cage-type bioreactors.(5) The coupling computation of multi-phase and sliding mesh is realized, and the hydrodynamics characteristics of cage-type bioreactors is numerical simulated. The computation results are positive related with experiment results, so the technology with multi-phase and sliding mesh is an efficient method for evaluation of bio-carriers space structure and optimization, and the inside structure of cage-type bioreactors is optimized. The optimized inside structure with proper hydrodynamics characteristics is obtained, which the length of inside lamina is 0.15 Rz, the number of inside lamina is 10, the profile of inside lamina is positive curve surface, the profile of outside lamina is spline.