The Development And Appilication Of High-Rate Anaerobic Reactors

High-rate anaerobic reactors are energy saving and environmental devices in the organic treatment of wastewater. The problems of the wastewater pollution and the energy sources are increasingly becoming the focal problems in the whole world , and organic pollution is the key one for wastewater pollution problems. Highly concentrated organic wastewater treatment is the important part of the organic wastewater treatment technologies which are concerned with people. However in recent days second and third generation anaerobic reactors are the primary reactors being studied and applied to the treatment of high-concentrate organic wastewater both at home and abroad. There are some factors that restrict the development of the anaerobic reactors in the treatment of high-concentrate organic wastewater at present. In this paper is described the attempt to solve the key theoretical and technological problems restricting the development of anaerobic reactors, and the consequent improvement in equipment.Four kinds of anaerobic reactors were designed in this paper: conventional UASB, hydraulic circulating compound UASB, hydraulic circulating compound screen UASB and mechanical mixing UASB. These four reactors were gradually improved. Three years were spent on tests of the properties of the reactors, and finally by way of hierarchical analysis, the hydraulic circulating compound UASB and mechanic mixingUASB were developed. Through the comparisons of sludge observation, the abilities of treating organic wastewater, the hydraulic conditions, etc., in reactors and the characteristics of the sludge and sludge structure.Mechanic mixing UASB and hydraulic circulating compound screen UASB designed in this paper is a bold advance on the conventional anaerobic reactor. The characteristics of the designed structure of reactors are the separation of sludge circulation, simple structure, easily controlled operation and condition and mass biomass, so the reactor research is believed to be successful. The concept about a new kind of reactor was put forward in this experiment, in which the hydraulic gradient replaced the velocity of flow .The structure makes wastewater and sludge to be completely miscible. The biochemical reaction in the reactor is at a high speed, and the sludge is at high consistency at the same time.The study focused on the start-up and performances of the mechanical mixing UASB and hydraulic circulating compound UASB treating artificial organic wastewater (most of the organic compound in the wastewater was flour). Experiments were done in the Rizhao citrate factory. Through the theoretic analysis of more than 1000 experimental data, the main conclusions are as follows:1. Having put forward the theory of granular sludge quick growth of high-rate anaerobic reactor, the formation of anaerobic granular sludge is due to the quickly growth of methane bacteria. Good mass transfer force is the basic requirement of high rate anaerobic reactor.2. Mechanical mixing UASB and hydraulic circulatingcompound screen UASB have the merit of being third generation reactors. Their superiority was proved by the hierarchical analysis.3. It is blieved Mechanical mixing UASB and hydraulic circulating compound screen UASB possess an advanced type of circulating sludge separation in comparison with the type of suspending sludge filter in the IC and EGSB on the basis of the mechanism of separation between water and anaerobic sludge.4. The self-adjusting ability of pH in the high-rate anaerobic reactors system was examined. The view of inadaptation to the environment of methane bacteria is put forward by observation of the acidation phenomenon of anaerobic reactors.5. High-rate anaerobic reactors have prodigious superiority for the treatment of differently concentrated organic wastewater and adaptability with organic loading.6. The deduced flow volume passing through the three-phase separation device and the stability of the refined disposal area can cause the retention of more sludge and lengthen the retention time of anaerobic bacteria.