What are the biological treatment methods of sewage
Source：Jiangsu Envset Time:09 June 2021
Types of modern biological treatment methods use the biochemical action of microorganisms in the natural environment to oxidatively decompose organic pollutants and certain inorganic poisons (such as fluoride and sulfide) dissolved in sewage or in the state of limbs, and convert them into stable Harmless inorganic substances, so that waste water can be purified. This method has the advantages of low investment, good effect, low operating cost, etc., and is the most widely used in the treatment of urban wastewater and industrial wastewater.
Types of modern biological treatment methods are classified into two types: aerobic biological treatment and anaerobic biological treatment according to whether microorganisms need oxygen in their biochemical reactions.
(1) Aerobic biological treatment method.
Under aerobic conditions, relying on the biochemical action of aerobic bacteria and facultative bacteria to complete the Wastewater treatment process is called aerobic biological treatment. This method requires aerobic supply. According to the state of aerobic microorganisms in the treatment system, it can be divided into activated sludge method and biofilm method.
1) The activated sludge method is currently the most widely used biological treatment method.
This method is to continuously pass air (aeration) into the wastewater rich in organic pollutants and bacteria in the aeration tank, and after a certain period of time, suspended flocculent mud particles will appear. This is actually caused by The aerobic bacteria (and facultative aerobic bacteria) adsorbed organic matter and aerobic bacteria metabolic activity of the product composed of aggregates, has a strong ability to decompose organic matter, called "activated sludge". After the mixed liquid of sewage and activated sludge flowing out of the aeration tank is settled and separated in the sedimentation tank, the clarified water is discharged, and the sludge is returned to the aeration tank as seed sludge, and the operation continues and the Wastewater treatment process has been completed.
2) The biofilm method is to make the sewage flow continuously through the solid filler (gravel, coal cinder or plastic filler), and the microorganisms multiply on the filler to form a sludge-like film called biofilm. The biofilm is used to treat sewage. Known as the biofilm method.
The biofilm is mainly composed of a large number of bacterial micelles, fungi, algae and protozoa. The microorganisms on the biofilm have the same purification effect as the activated sludge, adsorbing and degrading organic pollutants in the water. Types of modern biological treatment methods After sedimentation and separation in the sedimentation tank, the sewage can be purified. Commonly used biofilm methods include biological filter, biological contact oxidation pond, biological turntable and so on.
(2) Anaerobic biological treatment method.
Under anaerobic conditions, the method of using anaerobic microorganisms to decompose and decompose organic matter in sewage to purify sewage is called anaerobic biological treatment. In recent years, the world's energy shortage has caused sewage treatment to develop in the direction of energy conservation and realization of energy, thereby promoting the development of Anaerobic microbial treatment method. A large number of high-efficiency new anaerobic bioreactors have appeared one after another, including anaerobic biological filter, upflow anaerobic sludge bed, anaerobic sulfurized bed, etc.
Their common feature is that the concentration of biological groups in the reactor is very high, the sludge age is very long, so the processing capacity is greatly improved, so that the Anaerobic microbial treatment method has low energy consumption, can recover energy, and has a small amount of remaining sludge. The advantages of the generated sludge are stable and easy to handle, and high efficiency in the treatment of high-concentration organic wastewater. After years of development, the Anaerobic microbial treatment method has become one of the main methods of sewage treatment.
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Tags:types of modern biological treatment methods, wastewater treatment process, anaerobic microbial treatment method