Optimization Design And Research Of Performance Of EGSB

The anaerobic reaction technology is developing rapidly in the past ten years and has already played a important role in the industrial wastewater treatment. As representatives of the modern anaerobic reactor, such as UASB (Up-flow Anaerobic Sludge Bed), EGSB (Expanded Granular Sludge Bed) and IC (Internal Circulation), they have been applied widely. Therefore, it is a challenging issue to develop high-efficient anaerobic reactor and narrow the technological gap between developed countries and our country.We have improved EGSB based on the principle of EGSB and developed an IEGSB (Improved Expanded Granular Sludge Bed) at last. The IEGSB not only increases hydraulic up-flow velocity, for which influent could be better mixed with sludge and get excellent massing transfer efficiency, but also decreases the three-phase separator load, improving separation efficiency and maintaining high concentrations of granular sludge by increasing the ratio of height and diameter of the reactor and adopting effluent circulation technology before separation. The key technology of anaerobic reactor is the water distribution system and the three-phase separator. On one hand , we developed a cyclone-flow water distribution device which could improve water distribution uniformity basing on the knowledge of hydraulics and the experiences from practical operation; On the other hand, we developed an improved three-phase separator which called short distance tilted plate three-phase separator basing on conventional three-phase separator, the shallow theory and engineering experience. The improved separator could improve the separation effect of liquid, solid and gas, assuring the water quality of effluent.The research established a mathematical model of the IEGSB and simplified it by theory analysis. The simplified model is a good tool for the optimization design of reactor. According to this model, we developed a laboratory scale IEGSB. The operational performances of the cyclone-flow water distribution device and the short distance tilted plate three-phase separator of the reactor were studied in detail. Base on the small scale test and the pilot experiment, the external circular anaerobic technology was applied to the practical project. And the treatment effect of the operation was investigated seriously.Through the comparison experiment between tracer experiment and test with vertical water feed, we found that the reactor with cyclone-flow water distribution device had excellent uniformity of water distribution and sludge distribution along the height of the reactor, smaller energy consumption, unobvious sludge-water interface and high sludge bulking rate as well as volumetric utilization rate. The reactor with short distance tilted plate three-phase separator was more efficient to separate the liquid, solid and gas phase than the traditional one and had small sludge concentration in the effluent.Base on the small scale test and the medium trial, the external circular anaerobic technology was used in the actual engineering filially. According to the designed discharge and the designed water quality, the diameter, height of active sludge area, height of suspension layer, cyclone-flow water distribution device and short distance tilted plate three-phase separator of IEGSB could be calculated by the correlation formula and the correlation coefficient of the second chapter. After the project finished, the results of two months'running showed that the anaerobic system could run steadily and reliably, and the water quality of effluent met the design requirements.