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The role of dissolved oxygen in sewage treatment

by:BOQU     2023-03-18
What is dissolved oxygen? What is the relationship between dissolved oxygen and microorganisms? Oxygen dissolved in water is called dissolved oxygen. Organisms and aerobic microorganisms in water, the oxygen they depend on for survival is dissolved oxygen. Different microorganisms have different requirements for dissolved oxygen. Aerobic microorganisms need to provide sufficient dissolved oxygen. Generally speaking, dissolved oxygen should be kept at 3 mg/L, and the minimum should not be lower than 2 mg/L; the range of dissolved oxygen required by facultative microorganisms is 0.2-2.0 mg/L; and the range of dissolved oxygen required by anaerobic microorganisms is 0.2 mg/L or less. What does dissolved oxygen mean? Dissolved oxygen (DO) represents the amount of dissolved oxygen in water, and the unit is mg/L. Different biochemical treatment methods have different requirements for dissolved oxygen. In the facultative biochemical process, the dissolved oxygen in water is generally between 0.2-2.0mg/L, while in the SBR aerobic biochemical process, the dissolved oxygen in water is generally between 2.0-8.0mg/L. Therefore, when the facultative pool is running, The aeration volume should be small and the aeration time should be short; while in the operation of the SBR aerobic tank, the aeration volume is large and the aeration time is long, but we use contact oxidation, and the dissolved oxygen is controlled at 2.0-4.0mg/L. What factors are related to the dissolved oxygen content in wastewater? The concentration of dissolved oxygen in water can be expressed with Henry's law: when reaching solution balance: C=KH*P wherein: C is the solubility of oxygen in water when solution balance; p is the partial pressure of oxygen in gas phase; Relevant; increase the intensity of aeration to make the dissolved oxygen close to balance, and the activated sludge will also consume the oxygen in the water. Therefore, the actual dissolved oxygen in wastewater is related to water temperature, effective water depth (affecting pressure), aeration rate, sludge concentration, salinity and other factors. Who provides the oxygen needed by microorganisms in the biochemical process? The oxygen required by microorganisms in the biochemical process is mainly provided by the aeration device. What kind of dissolved oxygen meter can accurately feed back the dissolved oxygen content in sewage treatment in real time? Fluorescent dissolved oxygen is more suitable for sewage treatment because it will not be interfered by other ions in sewage, does not consume oxygen, is not limited by flow rate, does not require frequent calibration, has low maintenance, long service life, and can be monitored online for a long time. What are the advantages of the fluorescence dissolved oxygen sensor? 1) Master the core technology, unique leading fluorescent materials, sensitive response, more accurate measurement. 2) It has its own machining center and CNC machine tools. 3) There is an expert team for importing. Submerged aeration equipment: The motor directly drives the impeller to rotate, generating centrifugal force, which makes the nearby low-pressure water absorb and flow, and also sucks in air at the impeller inlet. In the mixing chamber, air and water are quickly expelled by centrifugal force. The latest aeration technologies include bubble-free aeration, catenary aeration and micro-nano aeration. Teach you to use and optimize, fully understand the operation skills of dissolved oxygen analyzer. Commonly used techniques and equipment: (1) Bubble-free aeration technology: water flows outside the tube, and the oxygen pressure is kept below the bubbles. Under the influence of the oxygen partial pressure difference on both sides of the membrane, the oxygen in the tube directly enters the water outside the membrane through the micropores or the membrane wall; (2) Hanging chain aeration technology: the aeration equipment mainly changes the fixing method of the traditional aeration equipment, adopts The float is aerated, suspended in the pool, with a hose connected between the aerator and the exhaust pipe. When the ventilator is ventilating, due to the uneven force, the ventilator moves in the water. When the aerator deviates from the vertical axis of the aerator, the air bubbles rise to the surface of the aerator and explode on one side of the aerator. (3) Micro-nano bubble generator: mainly composed of generator, micro-nano bubble generator and connecting pipe. Under the pressure of the water pump, the aeration stone in the aeration head rotates at high speed. Under centrifugal action, a negative pressure zone is formed inside the aerator head, and air enters the negative pressure zone through the inlet, and the negative pressure zone is divided into a surrounding liquid zone and a central gas zone in the container. Due to the small air bubbles, the air is not affected by the solubility of air in water, temperature, pressure and other external conditions, and can stay in the sewage for a long time, which has a good air flotation effect. The composition of the dissolved oxygen analyzer: 1. Digital sensor, rs485 output, the protocol is equipped with an automatic cleaning device, which can effectively remove sensor surface contamination, prevent microbial growth, more accurate, and lower maintenance. Fluorescent dissolved oxygen, electromagnetic conductivity, turbidity, ph, orp sensors are selected, suitable for comprehensive design, and can measure five parameters (including temperature) at the same time. 2. The multi-parameter water quality analysis sensor includes oxygen and fluoride dissolution rate, conductivity, turbidity, ph, P, temperature and self-purification device. 12v DC power supply, waterproof. 1 channel rs485 output optional sub-sensor description Fluorescent dissolved oxygen sensor detection range is 0.20mg/L or 0.200% saturation; electromagnetic transmission: 20s/cm600ms/cm, accuracy: 1.5%, electrode material: pp, working temperature: 0100c ; Optical fiber turbidity sensor, temperature: 0.11000ntu, accuracy: 5% or 0.3ntu, response time: 2 seconds, working temperature: 050; ph sensor online industrial ph electrode 485 interface, 0-14ph, fixture; or pp sensor range :-15000mv1500mv, precision: 15000m. 3. Fluorescence dissolved oxygen probe: 0-20mg/l accuracy 0.3mg/l Turbidity probe: 0-1000ntu accuracy 5% or 0.3ntu resolution 0.1ntu conductivity probe: 1us/cm-600ms/cm accuracy 1.5%fs resolution Rate 0-1000ms/cm: 1us/cm1ms1mv Resolution: Range: 0-0-500000mv1mv1mv.
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