Industrial wastewater is a pollutant discharged from industrial production, containing pollutants such as high concentrations of organic matter, inorganic matter, heavy metals or other harmful chemical substances, and some enterprises will discharge high concentrations, such as a chemical plant discharges high concentration of industrial wastewater with a COD concentration of 80,000mg L. In this case, the treatment of industrial wastewater is doubled.
At present, more and more enterprises are discharging high-concentration industrial wastewater, how do we design a feasible wastewater treatment system for the factory?
In the case of high concentration of refractory organic wastewater, this industrial wastewater is usually characterized by high concentration of organic matter and poor biodegradability, and a single wastewater treatment method - physical, chemical and biological methods are difficult to achieve good treatment results.
For example, we only use "advanced oxidation technology", although it produces a highly oxidizing hydroxyl radical (·OH), which can react with most organic matter to degrade and even mineralize, but this technology has disadvantages such as high treatment cost, failure to meet emission standards, and weak impact resistance.
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Anaerobic biological treatment is a common treatment method to solve the problem of high concentration and refractory organic wastewater (low treatment cost, low sludge production, high organic load, etc.), which can improve the biodegradability of wastewater and also has high COD removal capacity. However, it is sensitive to many factors, and the COD concentration of UASB influent water is generally controlled below 5000mg L, and it cannot be used in the face of ultra-high concentration of wastewater.
Therefore, we combine a variety of wastewater treatment methods with the treatment of industrial wastewater with high concentration, and use the advantages of different treatment methods to achieve ideal treatment results and effectively save treatment costs.
Recently, one of our chemical wastewater treatment projects has used "iron-carbon micro-electrolysis + air flotation + two UASB reactors + aerobic", which can meet the discharge standard of industrial wastewater with a COD concentration of 40,000mg L.
In the case of high-concentration ammonia nitrogen wastewater, this industrial wastewater will be used in fertilizer wastewater, monosodium glutamate wastewater, coking wastewater, landfill leachate, gas wastewater, aquaculture wastewater, etc. In the treatment of ammonia nitrogen wastewater with low concentration, biological method and adsorption method are used more, while our treatment of high-concentration ammonia nitrogen wastewater requires ion exchange method, chemical precipitation method, blowing method, etc.
In the case of pharmaceutical wastewater treatment, the "two-stage blowing method" was used to solve the industrial wastewater with ammonia nitrogen concentration of 2000mg l. Its principle is that under strong alkaline conditions, the ammonia nitrogen in the wastewater will mainly exist in the form of free ammonia, if the wastewater is continuously aerated to make the wastewater fully contact with the air, the gas-liquid balance relationship of ammonia will change and the volatile NH3 will be transferred from the liquid phase to the vapor phase, and then it will be removed.
When encountering high concentration of heavy metal wastewater, this industrial wastewater is different from the above two types of industrial wastewater, it cannot be decomposed by microorganisms, so most of the methods to solve heavy metal wastewater are mainly physical and chemical methods.
Chemical precipitation treatment method is the most widely used heavy metal wastewater treatment method, its principle is to put chemicals in heavy metal wastewater, heavy metal wastewater and chemicals have a chemical reaction, and then the heavy metal ions are precipitated and separated. The chemical precipitation treatment method is divided into neutralization precipitation treatment, barium salt precipitation treatment, sulfide precipitation treatment and ferrite precipitation treatment.
When we solve the problem of high-concentration industrial wastewater, we need to choose the appropriate wastewater treatment method according to the actual wastewater situation, so that it is easier to achieve the standard discharge and reduce the treatment burden of the enterprise.