Dissolved air flotation machine is the kind of wastewater pretreatment equipment commonly used in sewage treatment projects. The working principle of Dissolved air flotation machine is as followed: The air is delivered into and dissolved in the sewage to form dissolved water, and the pressure is reduced in a short time by the release device, so that the dissolved water generates a large amount of micro-bubbles. These micro-bubbles can adhere to impurities such as emulsified oil and oil residue, and form an air floating body having a density lower than that of water, so that it floats up to the surface of the water to form dross, thereby achieving the purpose of removing impurities such as oil. Dissolved air flotation machine is widely used to remove suspended solids, oils and fats from wastewater in the coking industry, paper industry, chemical industry, printing and dyeing industry, food processing, beer manufacturing, pharmaceutical industry, slaughtering and other industries. Dissolved air flotation machine produced by RUNNENG has characteristics of less investment, strong adaptability, simple structure, small equipment footprint, low operation and maintenance cost and high processing efficiency.
A coking plant in Weifang is a large-scale modern enterprise group that focuses on the development of coal chemical industry which integrates science, industry and trade. The main products are coke, carbon black oil, industrial naphthalene, modified asphalt, phthalic anhydride, PBT synthetic resin, lithium battery anode material, food additive ammonium bicarbonate, pure benzene, phenol, etc., more than 40 kinds, widely used in metallurgy, chemical industry, Pharmaceutical, food processing and other industries. The oil content of coking wastewater in Weifang coking plant is about 750mg/L. Now the unoiling effect of Dissolved air flotation machine is poor, and the COD of wastewater is high. It can not guarantee the oil content of the regulating tank is <75mg/L, which directly reduces the water quality and treatment effect of biochemical system, and sewage treatment effect.
RUNNENG engineers inspected and analyzed the operation of the on site Dissolved air flotation machine, and found that the original one has problems of equipment aging and the insufficient amount of micro-bubbles. These problems lead to the poor unoiling effect of Dissolved air flotation machine. Through comparative analysis, the engineers decided to choose RN-TDAF20 type Dissolved air flotation machine for Weifang customers.
Technical Parameters of Dissolved air flotation machine
- Dissolved air flotation machine Model is RN- TDAF20
- Treatment capacity is 20m3/h
- Water pump power is 3kw
- Scraper power is 0.37kw
- Size of Dissolved air flotation machine is 4800×1200×1500mm
Runneng brand air floater improvements
The oil removal effect of Dissolved air flotation machine is further improved by adjusting the air floater release mechanism, the water temperature of the sewage, and the gas-water ratio of the dissolved gas tank. The details are as follows:
- The copper TV-II type release device is used. The working diameter of release device is 600mm, and the released micro-bubbles are dense, and the diameter is 20-40μm. The compressed air can be used to move the lower plate to remove the blockage. It solves the problem that the original carbon steel material is easy to be corroded and needs to be shut down after being blocked.
- Optimize the structure of the releaser. The releaser distribution tube is transformed from a single linear structure to a grouped parallel structure. The release tube is divided into two groups, and the aeration head is installed on the distribution tube, so that the microbubbles can be more evenly distributed in the wastewater to ensure the oil adsorption effect. The two sets of release tube distribution tubes can also realize mutual backup. When a group of distributed tubes is blocked or cannot be used normally, the other group can be operated normally without affecting the use of Dissolved air flotation machine and the sewage treatment system.
- Adjusting the sewage temperature. A reasonable sewage water temperature plays an important role in the treatment effect of Dissolved air flotation machine. Based on rich design experience and comprehensive consideration of the degreasing effect, energy saving and environmental protection, Runneng engineers adjust the temperature adjustment of the sewage at 40-60 ℃.
- Adjust the gas-water ratio of the dissolved gas tank. Runneng engineers tested the steam-water ratio of the air-dissolving tank of Dissolved air flotation machine. The test results show that within a certain range, the larger the gas-water ratio, the greater the number of bubbles in the unit sewage. The increase in the number of bubbles causes the bubble to have a greater chance of contact with the oil molecules, and the oil droplets attached to the bubble also increase, and the degreasing effect increases. However, if the intake air volume is too large, the gas-water mixing section cannot form a uniform dissolved gas mixture, resulting in a decrease in the air-floating effect. In the end, Runneng engineers determined that the optimal gas-water ratio was about 3:1, and the pressure inside the dissolved gas tank was about 0.38MPa. Under this circumstance, the liquid level of the air flotation machine has a layer of tiny bubbles overflowing, and the overall degreasing effect of Dissolved air flotation machine is greatly improved.
In December 2018, through the transformation of the air flotation system of Weifang coking plant by Runneng, the degreasing effect of Dissolved air flotation machine was obviously improved, the oil content of Dissolved air flotation machine effluent <10mg/L, which improved the water output index and reduced the subsequent biochemical system treatment pressure. After testing, the renovation project also reduced the amount of flocculant and coagulant added in the pretreatment step by 24%, further saving operating costs, and Weifang customers expressed satisfaction.
About RUNNENG
Shandong RUNNENG Environmental Technology Co., Ltd (RUNNENG) had been dedicated to supplying one stop wastewater equipment and Water Resource Recovery Facility (WRRF) solutions to worldwide customers for over 20 years. RUNNENG has over 30 professional experts and more than 150 staffs. Our high quality innovative wastewater equipment includes dissolved air flotation equpiment, bar screen waste remover, sludge scraper and integrated sewage treatment equipment, etc. All our wastewater equipment has been passed the certificates of ISO9001, ISO14001 and OHSAS18001, we also have the Grade B engineering design certificate issued by the Ministry of Environmental Protection. Hope to be your partner.
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