China Water Network recently interviewed Wang Kaijun, chief engineer of the Beijing Academy of Environmental Protection Sciences. Chief Engineer Wang Kaijun has long been engaged in the research, development and technology promotion of water pollution control, and has presided over the design of many major wastewater projects. Governance project. He also presided over key research projects of the national “Seventh Five-Year Plan”, “Eighth Five-Year Plan”, “Ninth Five-Year Plan” and “Tenth Five-Year Plan”, and has extensive influence in the industry. Some time ago, the 863 project led by Chief Engineer Wang Kaijun just concluded. This project is one of the national major special water pollution control technology and treatment projects. It is jointly undertaken by the Beijing Academy of Environmental Protection Sciences, the Department of Environmental Science and Engineering of Tsinghua University, Xi'an Jiaotong University and Jinan Shifang Environmental Protection Co., Ltd. The project developed a new type of anaerobic bioreactor with independent intellectual property rights - "anaerobic compound circulating granular sludge suspended bed reactor". The anaerobic granular sludge suspended bed reactor absorbs the characteristics of modern high-efficiency anaerobic bioreactors such as UASB, EGSB and IC, comprehensively considers the operating characteristics of the reactor under high load, and designs a reasonable reactor height-to-diameter ratio. The circulation in the reaction zone, the effluent circulation and the biogas circulation make the reactor have the characteristics of high sludge bed, high sludge concentration, high mixing degree and high matrix degradation driving force. Based on the analysis of the characteristics of the upflow granular sludge bed (UASB and EGSB) reactors, the upflow reactor type, sludge granulation and phase separator are proposed. These basic structural types and new biological reaction phenomena are expanded By understanding the connotation of bioreactors, it can not only guide the development and application of new anaerobic reactors, but also further expand into the fields of aerobic and anoxic biological treatment. Therefore, the suspended bed reactor process inherits the form of the upflow reactor, emphasizing the unified role of granular sludge and biofilm particles, and keeping the particles (sludge) in a fully suspended state in the flow state. According to changes in the incoming water volume, water quality and reactor operating performance, the online composite feedback adjustment system uses a composite cycle method and technical means that combines internal and external water circulation and biogas circulation to promote the rapid formation and particle structure of granular sludge. and maintenance of activity, achieving full contact and mass transfer between the matrix and microorganisms in the reactor, and accelerating the reaction rate. It has the following characteristics: 1) By adjusting and controlling the degree of suspension of the sludge bed, it promotes the formation of granular sludge and its retention and renewal in the reactor. It also promotes the full integration of the gas/liquid/solid three phases in the reactor. Contact and mass transfer; 2) The ratio of internal and external water circulation and biogas circulation, the dosage (amount) of chemicals, etc. can be automatically adjusted and controlled through online instruments, which can achieve optimal control of pH and alkalinity in the reactor system ;3) By regulating the methods and proportions of internal and external composite circulation of effluent or biogas circulation, the efficient, low-consumption and stable operation of the entire system can be ensured. This project has achieved innovative results in aspects such as anaerobic suspended bed theory, anaerobic suspended bed reactor flow pattern, dynamics, and functional expansion. The demonstration project has been running for more than a year, and the load of the anaerobic suspended bed reactor is stable at 30~ 40kgCOD/m3.d, the maximum load reaches 52 kgCOD/m3.d, and the load index reaches the international advanced level of anaerobic bioreactors. It has applied for 5 national invention patents and formed a professional research team for high-efficiency anaerobic bioreactors. The results achieved have good social and economic benefits. In the interview, Chief Engineer Wang Kaijun mentioned that the current anaerobic technology is mainly divided into four aspects: industrial wastewater, anaerobic digestion and anaerobic treatment of urban sewage sludge, solid waste (including landfills, agricultural waste etc.) anaerobic treatment and rural biogas. Anaerobic digestion of urban sewage sludge is a relatively traditional field, but its technology, scale and application are difficult to compare with foreign countries. It has a certain relationship with economy, policy and technology, and the biggest problem is technical factors. Although some people believe that there are already very successful and technologically advanced projects in China, the success of one project does not represent the level of the overall level. Overall, there is still a big gap between domestic technology in this area and foreign countries. Anaerobic technology for industrial wastewater has developed rapidly in the past two decades, but there is still a certain gap compared with foreign countries. Among the entire anaerobic technology, only rural biogas in China has a certain foothold in the world, which mainly includes two aspects: one is the application of rural biogas chambers. There are more than 200 million farmers in the entire countryside, and by the end of 2004, 15 million households were running biogas chambers, which are the most widely used in the world. The second is the application of biogas septic tanks.
Biogas septic tanks are equivalent to non-powered reactors in sewage treatment. They are leading the world in the field of biogas. According to incomplete statistics, there are currently 100,000-200,000 biogas septic tank installations across the country. When talking about the reason why rural biogas leads the world, Wang Kaijun said that it is mainly because the Ministry of Agriculture has done a lot of work and policies have promoted the application of biogas. In the field of sewage, people in the industry (such as design institutes, sewage treatment plants, etc.) believe that anaerobic technology is relatively complex, and it is difficult for small and medium-sized factories to master the technology and operate it. Therefore, the policy recommends that sewage treatment plants with a capacity of less than 100,000 tons should not use anaerobic digestion. In comparison, 80% of some European and American countries use anaerobic sludge digestion. When asked about the relationship between anaerobics and sustainable development, Chief Engineer Wang Kaijun said that we must first start with the definition of sustainable development. The definition of sustainable development is different at the social level and at the technical level. In terms of political or administrative management, if a city has established a sewage treatment plant and the sewage discharge reaches the standard and is controlled, it can be said that the city has achieved sustainable development. The essence of sustainable development is development that meets the needs of the present without compromising the needs of future generations. Its core is the coordination of economic development with resource protection and ecological environment protection, so that future generations can enjoy sufficient resources and a good natural environment. Consider whether the consumption of resources, occupation of land resources, energy and other resources is reasonable. Technically, it is necessary to consider whether to adopt high energy consumption or low energy consumption, high land occupation or low land occupation technology, and also take into account the impact of high energy consumption on other industries. Anaerobic technology itself is a resource recovery technology with renewable energy. Under this premise, in terms of energy and resource consumption, anaerobic technology is the core technology of sustainable development. Chief Engineer Wang Kaijun’s research group has done many successful cases of anaerobic applications. For example, the high-concentration wastewater studied is suitable for anaerobic technology. Research on UASB began during the “Ninth Five-Year Plan”, and then began research on new high-efficiency anaerobic bioreactors during the “Tenth Five-Year Plan”. Among them, the treatment of starch wastewater is a very successful field. For starch wastewater with a concentration of 10,000 mg/l, the energy recovered from the specific treatment project is still supplied to the sewage treatment plant. At this time, the sewage treatment plant does not consume energy but is the energy output. Preliminary statistics indicate that the research group's processing projects in the starch industry account for more than 50%-60% of the country's total. In terms of the application of anaerobic technology, China has been more successful in the starch industry, with an annual biogas production of hundreds of millions of cubic meters, and the benefits are very considerable. In addition, there are applications in the agricultural field. Anaerobic technology for solid waste such as landfill waste is currently a new field. The development trend of anaerobic technology is on the one hand to develop towards high concentrations, such as sludge and feces with a solid content of more than 10%. On the other hand, it is developing towards low concentrations, such as domestic sewage with a COD content of only 300-500mg/l. Chief Engineer Wang Kaijun studied under G.lettingga, the inventor of UASB. Letga developed UASB in the 1970s, and was also one of the developers of EGSB, which was subsequently developed based on UASB. The application of UASB and EGSB in the world today exceeds 80%, and lettingtingga has made a great contribution to the development of anaerobic technology. It is worth mentioning that he did not apply for a patent after his invention at UASB. Lettingga said that technology serves all mankind. His noble personality is worthy of praise. In addition, he is very helpful and supportive to developing countries. Almost all of his students come from developing countries such as China, Southeast Asia, Africa, and South America. Every month or two, he invites students from various countries and colors to his home. In addition, from a professional perspective, UASB has been widely used in industrial wastewater, but he is interested in two other aspects: one is the anaerobic technology of urban sewage. Lettingga believes that anaerobic technology can only be applied in urban sewage. real promotion. At present, anaerobic treatment of urban sewage has been vigorously promoted in India, South America, Brazil, Colombia and other places. The second is the decentralized treatment technology of domestic sewage. This kind of anaerobic decentralized treatment with anaerobic as the core is in line with the idea of ??sustainable development. On the contrary, large-scale construction of sewage treatment plants such as laying pipelines is not in line with the idea of ??sustainable development.