Aerobic biological treatment     In 1912, Clark and Gage in the United Kingdom found that long-term aeration of sewage produced sludge, and the water quality was significantly improved. This phenomenon was studied by Arden and Lockgtt. The aeration test was carried out in a bottle. The bottle was emptied at the end of the test every day and restarted the next day. They stumbled upon the fact that the treatment was not as good as the bottle was cleaned and the sludge was attached to the bottle wall. Knowing the importance of leaving sludge on the bottle wall, they called it activated sludge. Subsequently, before the end of the test every day, they settled the aerated sewage in a static state, and only poured the upper layer to purify the water, leaving the sludge at the bottom of the bottle for use the next day, which greatly shortened the sewage treatment time. The process of this test was the first activated sludge process wastewater treatment plant built in 1916. Observing these brown flocculants under a microscope, you can see a large number of bacteria, as well as fungi, protozoa and metazoans, which form a unique ecosystem. It is these microorganisms (mainly bacteria) that use the organic matter in the sewage as a foodstuff for metabolism and reproduction, which reduces the content of organic matter in the sewage. Activated sludge can be divided into aerobic activated sludge and anaerobic granular activated sludge.     Microorganisms involved in activated sludge treatment need to continuously absorb the necessary nutrients from the surrounding sewage during their life activities, including carbon sources, nitrogen sources, inorganic salts and certain auxins. These substances must be sufficiently contained in the sewage to be treated. Carbon is an important substance that constitutes microbial cells. Microorganisms involved in activated sludge treatment have a large demand for carbon sources, generally in the case of BOD5, and should not be lower than 100 mg/L. Domestic carbon sources for domestic sewage are relatively sufficient. For some industrial wastewaters with insufficient carbon sources, carbon sources such as domestic sewage or starch should be added.     Nitrogen is an important element constituting proteins and nucleic acids in microbial cells. The nitrogen source may be derived from inorganic nitrogen compounds such as N2, NH3, and NO3, and may also be derived from organic nitrogen-containing compounds such as proteins, dong and amino acids. The nitrogen source in domestic sewage is sufficient and does not need to be added separately; industrial wastewater should consider whether nitrogen is sufficient, and if necessary, urea or ammonium sulfate can be added.     Phosphorus is an important element in the synthesis of nuclear proteins, lecithin and other phosphorus compounds, and plays an important role in the metabolism and transformation of microorganisms. Coenzyme I, coenzyme II, adenosine phosphate, and the like all contain phosphorus. Microorganisms mainly obtain phosphorus from inorganic phosphorus compounds. Insufficient phosphorus source will affect the activity of the enzyme, thereby affecting the physiological function of the microorganism. 3.2 Dissolved oxygen Reference sewage activated sludge treatment is mainly aerobic bacteria microbial population. According to the operating experience data, the dissolved oxygen concentration in the aeration tank should be no less than 2mg/L (subject to the outlet). The concentration of organic pollutants in local areas is high, the rate of oxygen consumption is high, and the dissolved oxygen concentration is not easy to maintain 2mg/L, which may be reduced, but not lower than 1mg/L. 3.3 PH value     The physiological activities of microorganisms are closely related to the pH of the environment. Only under the appropriate pH conditions can the microorganisms carry out normal physiological activities. Microorganisms involved in biological treatment of sewage generally have an optimum pH range of between 6.5 and 8.5. 3.4 Water temperature     The effect of temperature is very important. The microorganisms involved in the treatment of activated sludge are mostly mesophilic bacteria. The suitable temperature is 10 to 45 degrees Celsius. For safety, the temperature of activated sludge treatment is generally controlled at 15 to 35 degrees Celsius, and the growth of microorganisms is slower than 5 degrees Celsius. 3.5 Toxic substances     "Toxic substances" refers to certain inorganic and organic substances that have an inhibitory effect on the physiological activities of microorganisms, mainly heavy metal ions (such as zinc, copper, nickel, lead, chromium, etc.) and some non-metallic compounds (such as phenol, aldehyde, cyanide). Compounds, sulfides, etc.). The toxic effect of toxic substances on microorganisms has a quantitative concept. Only when toxic substances reach a certain concentration in the environment, the toxic and inhibitory effects are revealed. As long as the various toxic substances in the sewage are below this concentration, the physiological functions of the microorganisms are not affected. The role of toxic substances is also related to pH, water temperature, dissolved oxygen, the presence or absence of other toxic substances and the number of microorganisms, and whether or not they are domesticated. 4 Processing method Edit this paragraph     The aeration tank is a place where the activated sludge composed of microorganisms is thoroughly mixed with the organic pollutants in the sewage, and then degraded, absorbed and decomposed. It is the core of the activated sludge process. The function of the aeration system is to supply the aeration tank with the oxygen necessary for the growth of microorganisms and the decomposition of organic matter, and to mix and stir, so that the activated sludge is in full contact with the organic matter. In the aeration tank, a large amount of flocculent sludge particles that are observed by the naked eye are called activated sludge flocs. As organic pollutants are decomposed, the aeration tank adds a portion of the activated sludge daily, which is called residual activated sludge. Use a sludge pump to directly drain the outside of the system -- the sludge tank. 5 Basic Process Edit this paragraph (1) The sludge sedimentation ratio of the project reflecting the nature of the sludge - SV < 30% is preferred; the sludge volume index - SVI = 50 ~ 150, SVI = 100 is the best, and the sludge may expand if the SVI reaches 200 or more. , (2) The project reflecting sludge nutrition belongs to sludge nutrient determination project: BOD5; effluent ammonia nitrogen (at least 1mg/L); effluent phosphorus (at least 1mg/L); secondary sedimentation tank effluent DO is not less than 0.5mg/L . (3) dissolved oxygen DO dissolved oxygen (not less than l ~ 2mg / L); secondary sedimentation tank effluent DO is not less than 0.5mg / L. (4) Reflecting the environmental conditions of the sludge, water temperature, pH value, BOD5, CoDcr, toxic substances, CN-, S2-, SS, NO3-, NO2-, etc. 6 Related Policies According to the current “Technical Policy for Urban Sewage Treatment and Pollution Prevention and Controlâ€: 1. The sludge produced by urban sewage treatment should be stabilized by methods such as anaerobic, aerobic and composting. It can also be disposed of properly by sanitary landfill. 2. The sludge produced by the secondary treatment facilities of sewage with a daily treatment capacity of more than 100,000 cubic meters should be treated by anaerobic digestion process, and the generated biogas should be comprehensively utilized. The sludge produced by the sewage treatment facilities with a daily processing capacity of less than 100,000 cubic meters can be composted and comprehensively utilized. The sewage treatment facilities using the delayed aeration oxidation ditch method, the SBR method and the like, the sludge needs to be stabilized. The sewage treatment facilities using the physicochemical first-stage strengthening treatment shall be properly treated and disposed of. 3. After the treated sludge reaches the requirements of stability and harmlessness, it can be used in farmland; sludge that cannot be used in farmland should be disposed of in sanitary landfill according to relevant standards and requirements. The Biomonitor online BOD analyzer developed by Yingnuo Instruments (Shanghai) Co., Ltd. is based on the activated sludge method to measure BOD and sludge toxicity. The dual-channel 40-series reaction tank is used to shorten the detection time and be accurate and effective. .  good fresh frozen squid Fresh Frozen Squid,Frozen Fresh Squid,Delicious Frozen Squid,Delicious Fresh Frozen Squid Strip Zhoushan Junwei Aquatic Products Co., Ltd. , https://www.junweiaquatic-intl.com
Active sludge is a general term for microbial populations and the organic and inorganic substances to which they depend . The microbial population mainly includes bacteria, protozoa and algae. Activated sludge is an aerobic biological treatment method . It was first discovered by the British Clark and Cage in 1912 that long-term aeration of wastewater produced sludge and improved water quality. Later, Arden and Lackett further studied and found that The experimental container was not cleaned, and the residue on the wall of the bottle caused the treatment effect to be improved, thereby discovering the active microbial cellulite group, which was named as activated sludge . Complex microbes in activated sludge and organic nutrients in wastewater form a complex food chain