Chemical enterprises are bound to discharge industrial wastewater, and it is a relatively difficult wastewater to treat, such as process wastewater, cooling water, exhaust gas washing water, equipment and site washing water in the production process. We need to use a variety of wastewater treatment methods to solve the problem of chemical wastewater, so that it can meet the discharge standards and reduce the impact of wastewater on the surrounding environment.
The physical method is a relatively common wastewater treatment method, which is applied in the pretreatment process and advanced treatment process, including filtration, sedimentation, air flotation, adsorption and other methods. Many of these chemical wastewaters contain a lot of grease and can be physically removed.
The air flotation method is to pass a large number of tiny bubbles in the water, and make these bubbles attach to the suspended particles, and use buoyancy to make the suspended matter float on the water surface, so as to achieve the purpose of separation.
Although this method is simple, easy to operate and low cost, it is difficult to remove soluble organic matter.
Chemical method is a key wastewater treatment method in chemical wastewater, including chemical oxidation, chemical coagulation, electrolysis, etc. We can use chemical oxidation in the pretreatment process to remove part of the organic matter of chemical wastewater, and improve the biodegradability of wastewater, and then use water for subsequent biochemical treatment.
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Fenton oxidation method is a more common chemical oxidation method, which uses the chain reaction between Fe2+ and H202 to catalyze the generation of hydroxyl radicals to oxidize various toxic and refractory organic substances to achieve the purpose of removing pollutants. With the development, this method will also be combined with other methods to achieve better wastewater treatment results and reduce wastewater treatment costs, which is called Fenton-like oxidation method.
The biological method is a frequent customer to solve the organic wastewater, and the organic matter in the wastewater can be degraded through the metabolism of microorganisms, and there are anaerobic biological treatment methods and aerobic biological treatment methods.
Nowadays, anaerobic biological treatment plays an important role in solving the problem of chemical wastewater, it can not only operate in the case of high organic load, but also has a high COD removal rate, which can reach more than 80%, degrading the organic matter in the wastewater into carbon dioxide, methane and other substances, and can play a role in improving biodegradability.
For example, in one of our cases, the "biochemical treatment process" is used as the leading factor, using the UASB reactor (the representative of the second-generation anaerobic reactor) and the contact oxidation tank, the chemical wastewater with a COD concentration of 8000mg L can be discharged up to the standard and complete the purpose of purification.
At present, chemical wastewater is becoming more and more complex, it contains a variety of different types, different properties of toxic and harmful substances, to achieve its harmless treatment, a method "alone is difficult to support", the treatment cost also increases, so to solve the chemical wastewater, to meet the requirements of the discharge standard, we need to adopt a combined wastewater treatment method.
For example, in the "maleic anhydride wastewater treatment project" (COD concentration of more than 30,000mg L), we not only use pretreatment methods such as air flotation and electrochemical methods, but also use two UASB reactors, multiple contact oxidation tanks and membrane tanks in the biochemical treatment method to remove organic matter in chemical wastewater and achieve standard discharge.