The aeration tank uses the activated sludge method for sewage treatment. The tank provides a certain sewage retention time to meet the oxygen content required by aerobic microorganisms and the mixing conditions for full contact between sewage and activated sludge. The aeration tank is mainly composed of a tank body, an aeration system, and a water inlet and outlet. The pool body is generally made of reinforced concrete, and the plane shapes are rectangular, square, and round.
Aeration methods can be divided into two types, mainly including blast aeration and mechanical aeration. The air is pumped into the aeration tank by an air compressor, and the machinery is generally rotated by the mechanical impeller installed in the aeration tank to violently stir the wastewater in the tank, to dissolve the oxygen in the air into the water.
An aeration tank is also a part of the biological treatment system. As it is very important in the whole sewage treatment system, the methods used are also being developed constantly. Generally speaking, the aeration tank is developing towards high efficiency, small size, and energy saving.
Electromagnetic Flowmeters (EMF for short) are a new type of flow measurement instrument that developed rapidly with the development of electronic technology from the 1950s to the 1960s. An electromagnetic flowmeter is an instrument that measures the flow of conductive fluid according to the electromotive force generated when the conductive fluid passes through the external magnetic field by applying the principle of electromagnetic induction.
Because there are many impurities in the sewage, the medium composition is complex and corrosive, the electromagnetic flowmeter can effectively overcome these problems, and the price of the electromagnetic flowmeter is relatively affordable and cost-effective. In the current sewage treatment industry, most of the flow measurement is realized through an electromagnetic flowmeter.
The vortex flow meter is a kind of volume flow meter that is researched and produced according to the Karman vortex street principle to measure the volume flow of gas, steam, or liquid, the volume flow of standard conditions, or the mass flow. It is mainly used for flow measurement of medium and fluid in industrial pipelines, such as gas, liquid, steam, and other media.
The vortex flowmeter in sewage treatment is generally used to measure the amount of oxygen flowing into the aeration tank, and the oxygen is sent into the aeration tank by an air compressor or blower, which is good like the blower, and the air compressor will have severe vibration when used generally. If a low-quality vortex flowmeter is selected, it will be damaged in two days. Therefore, the vortex flowmeter used for sewage treatment must be a high-quality vortex flowmeter with strong seismic resistance.
A pH meter is a kind of commonly used instrument and equipment, which is mainly used to precisely measure the pH value of a liquid medium. With a corresponding ion selective electrode, it can also measure the MV value of ion electrode potential. pH meter is widely used in environmental protection, sewage treatment, scientific research, pharmacy, fermentation, chemical industry, breeding, tap water, and other fields.
ORP meter, also known as an oxidation-reduction potential online analyzer, is an instrument widely used in industry and experiments; ORP, as a comprehensive indicator of environmental conditions of media (including soil, natural water, culture medium, etc.), has been used for a long time. It represents the relative degree of oxidation or reduction of media. The unit of ORP is mv.
The electrodes of the pH meter and ORP meter are consumables, and the actual measurement accuracy and service life are all determined by the electrodes. Choosing the right electrode can double the service life. It is recommended that you never choose the poor pH/ORP electrode on the market for measurement unless you want to change an electrode in two days.
Conductivity is the ability of a solution to conduct electric current. The conductivity of water is related to the amount of inorganic acid, alkali, and salt it contains. When their concentration is low, the conductivity increases with the increase of concentration. Therefore, this indicator is often used to predict the total concentration or salt content of ions in water. The conductivity can reflect and reflect the content of dissolved organic matter in the sewage. The higher the conductivity is, the higher the cod is. It is necessary to measure the conductivity to control the effect of the entire sewage treatment.
The dissolved oxygen meter is mainly used for continuous monitoring of dissolved oxygen value in chemical fertilizer, metallurgy, environmental protection, pharmacy, biochemistry, food, tap water, and other solutions. Conventional dissolved oxygen meters can be roughly divided into the membrane method (polarography) and fluorescence method according to the principle.
The dissolved oxygen in the aeration tank is a very important indicator. Because of the complex medium composition in the sewage, it is very difficult to measure it with the membrane-dissolved oxygen meter. However, the fluorescence dissolved oxygen meter only reacts with oxygen molecules, and will not be interfered with by sulfide and polarized. The service life of the membrane head is more than one year, which greatly reduces the maintenance cost.
Chemical Oxygen Demand (COD) is a chemical method to measure the amount of reducing substances in water samples that need to be oxidized. Oxygen is the equivalent of substances (generally organic substances) that can be oxidized by strong oxidants in wastewater, the effluent of wastewater treatment plants, and polluted water. In the research of river pollution and industrial wastewater properties, as well as in the operation and management of wastewater treatment plants, it is an important and fast-measuring organic pollution parameter, often expressed by the symbol COD.
The analyzers for COD and ammonia nitrogen are generally called "big meters" in sewage flow meters, and the purchase amount accounts for the largest part of the analytical instruments required for the whole sewage treatment. Therefore, you must be careful when purchasing such products. After all, each one is expensive!
The phosphorus is the result of determination after the water sample is digested and transformed into orthophosphate. It is measured in milligrams of phosphorus per liter of the water sample.
There are three common determination methods of orthophosphate:
① Vanadium molybdenum phosphoric acid colorimetry. The sensitivity of this method is low, but there are few interfering substances.
②Molybdenum antimony scandium colorimetry. High sensitivity, stable color, and good repeatability.
③ Stannous chloride method. Although sensitive, it has poor stability and is interfered with by chloride ions, sulfate, etc.
The harm of phosphorus to natural water bodies The discharge of excessive nutrients (mainly nitrogen, phosphorus, etc.) in natural water bodies causes abnormal reproduction and growth of various aquatic organisms and plants. This phenomenon is called water eutrophication. Therefore, the treatment of phosphorus in sewage treatment must meet the standard, otherwise, it will cause huge damage to the environment.
Ammonia nitrogen wastewater mainly comes from fertilizer, coking, petrochemical, pharmaceutical, food, garbage landfill, etc. A large amount of ammonia nitrogen wastewater discharged into the water body not only causes eutrophication and a black odor to the water body, but also increases the difficulty and cost of water supply treatment, and even produces toxic effects on people and organisms. The treatment processes for ammonia nitrogen wastewater include biological and physicochemical methods.
According to different test standards, ammonia nitrogen testers are of types A and B. Type A adopts Nessler's reagent colorimetric method GB7479-87; Type B adopts the salicylic acid photometric method specified in the national standard GB7148-81 and the international ISO7150/1-1948 as the basic test method, supplemented by the pretreatment of sample colorimetric reaction, to achieve rapid and accurate colorimetric determination of samples, which has the advantages of stability, sensitivity, reliability, and mercury free.
In the measurement, the ultrasonic pulse is sent out by the sensor (transducer), and the acoustic wave is received by the same sensor or ultrasonic receiver after being reflected by the liquid surface. It is converted into an electrical signal through piezoelectric crystals or magnetostrictive devices, and the distance from the sensor to the measured liquid surface is calculated by the time between the transmission and reception of the acoustic wave. Due to the non-contact measurement, the measured medium is almost unlimited and can be widely used for the height measurement of various liquid and solid materials.
Liquid level measurement is required for many links such as grit chambers, primary sedimentation tanks, and secondary sedimentation tanks in sewage treatment, and such liquid level measurement is generally realized by ultrasonic level gauge. Since there are often many foams in sewage treatment, the ultrasonic level gauge must be selected with strong penetrability. If there is too much foam, it is recommended to use a radar level gauge.
The ultrasonic sludge interface meter is specially designed for continuous online monitoring of the sludge interface in the sewage treatment process. The instrument uses the reliable ultrasonic echo detection principle to realize the real-time detection of sludge thickness and provide reliable data for the process control of related processes, thus optimizing the process control flow of sludge discharge and dosing.
The mud water interface instrument is used in the primary sedimentation tank and secondary sedimentation tank of sewage treatment. Although its popularity is not very high, it is also an indispensable important instrument in sewage treatment.