History of mainstream wastewater treatment technology

Chronicle of the development of sewage treatment technology

The history of sewage treatment can be traced back to the ancient Roman period. In that period, the environmental capacity was large, and the self-purification capacity of water body could meet the water demand of human beings. People only need to consider the drainage problem. Later, with the acceleration of urbanization, domestic sewage caused the spread of infectious diseases through the transmission of bacteria. For health reasons, humans began to treat the discharged domestic sewage. The early treatment methods were lime, alum precipitation and bleaching powder disinfection. In the late Ming Dynasty, China has sewage purification equipment, but because the demand is not strong, China's domestic sewage is still used for agricultural irrigation.

In 1762, the United Kingdom began to use lime and metal salts to treat urban sewage.

In 1881, French scientists invented the first bioreactor, and the first anaerobic biological treatment tank moris tank was born, which opened the prelude to biological treatment of sewage.

In 1893, the first biological filter was put into use in Wales, England, and quickly promoted in Europe, North America and other countries.

In 1912, the British Royal Commission on Sewage Treatment proposed BOD5 to evaluate the degree of water pollution. The development of technology has promoted the emergence of standards.

In 1914, since the advent of activated sludge method secondary biological treatment technology in Manchester, England, it has been widely used in the world, and developed countries have popularized secondary biological treatment technology. However, in view of the problems existing in the activated sludge method, researchers in various countries continue to transform and develop the technology. There have been ordinary activated sludge method, anaerobic/anoxic/aerobic activated sludge method (A/O, A/ A/O), batch activated sludge method (SBR method), improved SBR (MSBR) method, integrated activated sludge method (UNITANK), two-stage activated sludge (AB) method and various types of biofilm method.

Sewage treatment technology in economically developed countries from the end of the treatment in the 1960s to the prevention and control combination in the 1970s, from the centralized treatment in the 1980s to the clean production in the 1990s, and constantly update the treatment technology, facilities and equipment. At present, the main development trend of sewage biological treatment technology is the new technology and new process of combining various technologies. Such as synchronous denitrification and phosphorus removal aerobic granular sludge technology, electrical/biological coupling technology, adsorption/biological regeneration process, biological adsorption technology, and the use of light, sound, electricity and efficient biological treatment technology combined with the treatment of high concentration of toxic, harmful and difficult to degrade organic wastewater new physical, chemical, biological treatment combination technology, Such as photocatalytic oxidation biological treatment new technology, electrochemical advanced oxidation/efficient biological treatment technology, ultrasonic pretreatment/efficient biological treatment technology, wet catalytic oxidation/efficient biological treatment technology and radiation decomposition biological treatment combination process. In many countries, there have been major changes in the objectives and technical routes of water pollution control, and the objectives of water pollution control have been changed from the traditional sense of "sewage treatment, standard discharge" to "water recycling" with water quality regeneration as the core, and from the simple "pollution control" to "water ecological restoration".

History of sewage biological treatment technology

The traditional view is that the main function of biological treatment is to decompose and stabilize organic matter, that is, to reduce BOD. With the development of industrial production and long-term observation and research on the water environment, many synthetic organic matter has "three causes" (carcinogenic, teratogenic, mutagenic) serious harm, and is difficult to be degraded by microorganisms, while inorganic nutrients such as nitrogen and phosphorus are easy to cause water eutrophication. Therefore, the requirements of water treatment are also changing, in addition to requiring the water treatment process to have the function of nitrogen and phosphorus removal, but also require the industrial production, through high temperature and high pressure synthesis of various pollutants in the sewage treatment process to be effectively controlled. Because the degradation of this kind of substance in nature takes hundreds of years or even thousands of years, it will continue to enrich and increase its concentration, directly endangering the ecological environment and the health of human life. Is biological treatment effective for this type of wastewater treatment? Some BOD, COD concentration is very high, even up to tens of thousands of mg/L of sewage, biological treatment technology can be effective? These new problems and requirements have promoted the development of biological wastewater treatment technology and process.