At present, most of the domestic chemical enterprises are small in scale, and the technology development and application are lagging behind. The main products of the enterprises are pesticides, medicines, fertilizers, etc., with extensive production and low technological level. Production sewage generally has many organic and toxic components, high ammonia nitrogen content, high acidity, deep chromaticity, etc., which cause great pollution to water quality, and sewage treatment technology is difficult.
Mixed chemical wastewater generally refers to the waste material formed in industrial production, which contains a large number of components that pollute the natural environment. These pollutants:
First, sewage is mainly mixed wastewater formed by industrial production and domestic wastewater, and the amount of wastewater discharged from chemical enterprises is far greater than the content of domestic sewage. Second, the amount and water quality of the treated chemical wastewater have obvious changes, and the fluctuation range is large. Third, even if the sewage has undergone preliminary basic treatment before being treated by the treatment plant, the sewage has many types of substances and complex structures. Moreover, the content of toxic substances is high, the treatment is difficult, and the value of treatment and reuse is low. . Fourth, after the basic treatment in the early stage, the components such as COD meet the requirements. However, problems such as high salinity and ammonia nitrogen components and high sewage concentration are still difficult problems in sewage treatment.
Analysis of processing technology
2.1 Physicochemical treatment process
2.1.1 Water quality and quantity regulation
The quality and quantity of mixed chemical wastewater produced by the sewage treatment station have obvious changes, large fluctuations, and difficult to fix, which will make the sewage treatment process affected by unpredictable quantity and quality, technical equipment is difficult to operate normally, and the stability is poor. Equipment treatment operation failure, resulting in damage to treatment equipment, affecting the quality and efficiency of wastewater treatment. In this regard, measures need to be taken to adjust the water quality and quantity. It is commonly used that the sewage collected by the treatment plant is discharged into a tank with homogenization of water quality components and water volume adjustment treatment, and then the sewage treatment process is further carried out after adjustment treatment.
2.1.2 Oily organic matter isolation treatment
Mixed chemical wastewater contains a large number of oily pollutants with extremely poor water solubility. They have extremely high adsorption performance and can adsorb active organisms on the surface of wastewater biofilm and oily sludge particles, so as to isolate them from the acquisition of oxygen. The activity decreases or even disappears, which affects the efficiency of sewage treatment. Therefore, to improve the effect of sewage treatment, it needs to be scientifically treated. In this regard, for the treatment of the above pollutants, the chemical wastewater with oily organic matter can be discharged into the oil separator, and the organic matter sedimentation can be carried out to separate the wastewater from the oily matter and reduce the content of precipitated substances in the wastewater. Further treatment through pharmaceutical technology can reduce the oily organic matter in the wastewater and improve the treatment effect.
2.1.3 Air flotation treatment
The treatment process is mainly based on the device with bubble making performance. In the sewage treatment, through the abundant bubbles with high dispersion, the suspended particles in the sewage are adsorbed, the bubbles float, and the substances are separated from the waste water. The adsorption objects are mainly hydrophobic solid suspended particles and oily suspended substances. The air flotation methods used in my country are generally pressurized dissolved air, rotary cutting air flotation, and vortex concave air flotation.
2.1.4 Coagulation treatment
The technical principle is to inject a coagulant into the treated wastewater, mix it with the sewage, and through a series of chemical and physical reactions with each other, the suspended pollutants and the poorly precipitable substances in the wastewater will coagulate each other in the wastewater. Together, larger particles are formed and separated from the wastewater. Coagulation treatment methods often need to be used in conjunction with sedimentation, air flotation and other technologies to ensure the quality of wastewater separation. The coagulant is generally selected to use a mixed type, and it is not recommended to use a single type of coagulant.
2.2 Biochemical treatment process
2.2.1 Hydrolysis and acidification
The treatment technology uses anaerobic reaction technology to control the acidification of microorganisms in wastewater, decomposes the organic molecular particles with larger molecules that are difficult to degrade into small molecular particles, and improves the biological utilization rate of wastewater. Preliminary preparation. The technology is less affected by the environment, has lighter adaptability, high acid-base adaptability, fast technology start-up speed, high operating stability, can be hydrolyzed and acidified at room temperature, and master the water electrolysis process and conditions. The effect of this treatment technique is ideal.
2.2.2 Anaerobic aerobic process method (AO treatment method)
The method mainly controls the hydraulic retention time of the anaerobic section and the aerobic section, so as to realize the control of the pH, solubility and other properties of the wastewater. The anaerobic section (A) is used for denitrification and phosphorus removal; the aerobic section (A) O), for the removal of organic matter in water. Achieve the effect of reducing the chromaticity and content of pollutants in the sewage, and improve the utilization rate of the organisms in the wastewater. Its advantage is that in addition to degrading organic pollutants, it also has certain functions of denitrification and phosphorus removal. It uses anaerobic hydrolysis technology for the pretreatment of activated sludge, so the AO method is an improved activated sludge method. .
2.2.3 PACT wastewater treatment method
The method is an activated sludge-powder activated carbon technology, which has a wide range of applications and is widely used in the treatment of mixed chemical wastewater such as petrochemical, coking wastewater, and papermaking. In addition, its nitrification effect is obvious. In the process of environmental treatment in various cities, the treatment effect of ammonia nitrogen and chroma is better, and it is often used in urban decontamination treatment. In the method, an appropriate amount of powdered activated carbon is added to the wastewater, so as to reduce the organic load in the wastewater and enhance the efficiency of organic matter treatment of the wastewater in the biochemical system.
In the process of mixed chemical wastewater treatment in enterprises, it is necessary to control the cost of wastewater treatment as much as possible. The wastewater can be preliminarily treated, and then collected in the wastewater treatment industrial zone for centralized and professional treatment. This process can reduce the treatment cost of the enterprise, and can also reduce the unreasonable method of sewage treatment in the enterprise, and the lack of scientificity leads to the occurrence of poor sewage treatment effect, which has a significant effect on reducing wastewater pollution and improving wastewater treatment.