Wastewater treatment is extremely important!

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Why is it necessary to install a homogenization tank in wastewater treatment systems? The wastewater discharged by industrial enterprises often exhibits significant fluctuations in parameters such as water quality, volume, pH level, and temperature over time. Such variations are highly detrimental to the proper operation of wastewater treatment facilities, especially those used for biological treatment, as they can prevent these facilities from performing their purification functions effectively, or even lead to their complete failure. Therefore, for comprehensive wastewater treatment plants, since multiple types of wastewater are discharged and their quality and quantity change frequently, it is essential to install a homogenization and regulation tank. The function of the homogenization tank is to overcome the unevenness in wastewater discharge, to balance variations in wastewater quality, volume, and temperature, to store excess amounts and make up for shortages, thereby ensuring a steady flow of water into the biological treatment facilities. This helps to reduce the adverse effects caused by such inconsistencies on the subsequent secondary biological treatment processes. Furthermore, acidic wastewater and alkaline wastewater can also be neutralized with each other in a regulating tank. What is the purpose of installing a homogenization and regulation tank in a wastewater treatment system? The purposes of such a tank are as follows: (1) To enable factories that operate on an intermittent basis to continue feeding wastewater into the biological treatment system even when production stops, thus maintaining the continuous and stable operation of the biological treatment system; (2) To enhance the system’s capacity to handle fluctuations in organic load, preventing sudden changes in the organic load within the biological treatment system; (3) To homogenize the incoming wastewater, preventing high-concentration toxic substances from entering the biological treatment system; (4) To control large fluctuations in pH levels, reducing the amount of acid or base required during the neutralization process; (5) To avoid fluctuations in the flow rate entering the primary treatment units, thereby ensuring smooth automated operation of processes such as chemical dosing; (6) In factories without biological treatment facilities, a homogenization tank helps to regulate the amount of wastewater discharged into the municipal system, helping to mitigate variations in wastewater loads. What are the types of homogenization and regulation tanks? These tanks can be classified into the following categories: (1) Equalization tanks: The commonly used equalization tanks are actually reservoirs with variable water levels, suitable for wastewater treatment plants that operate in two shifts and need to function continuously 24 hours a day. (2) Homogenization tank: The most common type of homogenization tank is the cross-flow homogenization tank. In an asynchronous homogenization tank, the water level is fixed; therefore, it can only achieve homogenization, not equalization. (3) Homogenization tank: The homogenization tank combines the functions of a equalization tank and a homogenization tank. (4) Intermittent homogenization tank: When the water volume is small, a homogenization tank with intermittent water storage and operation can be used. Intermittent homogenization tanks are reliable but not suitable for high-flow wastewater. (5) Accident regulating tank. What are the mixing methods used in homogenization tanks? Common mixing methods include: forced circulation using water pumps; air agitation; mechanical stirring; and water introduction via perforated channels. What are the characteristics of the air stirring method used for mixing in homogeneous equalization tanks? Air stirring not only serves to mix and homogenize the contents of the tank but also has a pre-aeration function: it prevents solid substances in the water from settling at the bottom of the tank and avoids anaerobic conditions. It also helps to oxidize reducing substances in the wastewater, removes volatile substances through stripping, thereby reducing the BOD5 value of the wastewater, improving the efficiency of primary sedimentation, and reducing the load on the aeration tank. The disadvantage of air agitation is that it can cause volatile substances in the wastewater to escape into the air, resulting in odors; sometimes it is necessary to install devices on top of the tank to capture and discharge these gases. When stirring is carried out using perforated aeration pipes in the homogenization tank, the aeration intensity is generally 2–3 m3/(m·h) or 5–6 m3/(m2·h). When the suspended solids content in the influent water is 200 mg/L, the power required to maintain a suspended state is 4–8 W/(m3 of wastewater). To maintain an aerobic condition in the wastewater, the required air volume is on average 0.6–0.9 m3/(m3·h). During air agitation, the air distribution pipes remain submerged in water throughout the year; using ordinary carbon steel pipes can lead to corrosion and damage, so corrosion-resistant materials such as fiberglass or ABS plastic must be used, and the installation requirements are quite high. What are the basic requirements for setting up a homogenization tank? The basic requirements for a homogenization tank are as follows: (1) To ensure uniform water quality in the effluent from the homogenization tank and to prevent the precipitation of pollutants within it, mixing devices should be installed in such tanks. Methods such as water pump circulation stirring, air stirring, jet stirring, and mechanical stirring can be employed. Among these, air stirring is widely used due to its simplicity, ease of implementation, and good effectiveness; the intensity of air stirring is generally 5–6 m3/(m2*h). (2) The retention time depends on the composition and concentration of the wastewater, as well as the volume and fluctuations in water flow; generally, it is 10 to 24 hours based on the water volume, and in special cases it can be extended to 5 days. The regulating tank can also serve to store wastewater from accidents; if it is primarily used for this purpose, it is necessary to maintain a low water level at all times. (3) Homogenization tanks, intended for improving water quality, are generally connected in series within the main wastewater treatment process, while volume regulation tanks can be connected in series within the main process or in parallel within auxiliary processes. (4) The depth of the homogenization tank should not be too shallow, with an effective water depth generally ranging from 2 to 5 meters; to ensure safe operation, the homogenization tank must be equipped with overflow outlets and sludge discharge outlets. (5) If the wastewater contains foaming substances, defoaming equipment should be installed; if it contains volatile gases or organic compounds, it should be covered to keep it sealed, and an exhaust system should be provided to discharge the volatile harmful gases (which are produced in greater amounts during mixing) into the air at regular intervals or continuously.