What is the history of wastewater treatment technology?

The demand for sewage treatment is accompanied by the birth of the city. After hundreds of years of changes, urban sewage treatment technology has developed from the initial primary treatment to the current tertiary treatment, from simple disinfection and precipitation to organic matter removal, nitrogen and phosphorus removal to deep treatment and reuse. Among them, the advent of activated sludge method is of epoch-making significance. This year marks the 106th anniversary of the birth of activated sludge method. How will urban sewage treatment technology develop in the future? In this regard, let's first review the road that urban sewage treatment has gone through in those years.

History of sewage treatment technology

The history of urban sewage treatment can be traced back to the ancient Roman period, when the environmental capacity was large, the self-purification capacity of the water body could also meet the water needs of humans, and people only need to consider the drainage problem. Then, with the acceleration of urbanization, domestic sewage caused the spread of infectious diseases through the transmission of bacteria. For health considerations, humans began to treat the discharged domestic sewage. The early treatment methods used lime, alum and other precipitation or bleach powder for disinfection. In the late Ming Dynasty, there were sewage purification devices in China. However, because the demand was not strong at that time, domestic sewage in China was still dominated by agricultural irrigation. In 1762, the United Kingdom began to use lime and metal salts to treat urban sewage.

In the mid-18th century, the Industrial Revolution in Europe began, among which organic matter in urban sewage became the focus of removal. In 1881, French scientists invented the first bioreactor, and also 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. The development of technology has promoted the emergence of standards. In 1912, the British Royal Commission on Sewage Treatment proposed BOD5 to evaluate the degree of water pollution.

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 the first 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 method (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 a combination of new technologies and new processes. 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 and 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 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 and restoration".

History of bioprocessing 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 removal and phosphorus removal, but also requires 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 substances in nature takes hundreds of years or even thousands of years, will continue to enrich, the concentration continues to increase. Direct harm to the ecological environment and human health. Whether biological treatment technology is effective for this type of sewage treatment, some BOD, COD concentration is very high, and even up to tens of thousands of mg/L of sewage, biological treatment technology can be effective, these new problems and new requirements have promoted the development of the world's sewage biological treatment technology and process methods.