Abstract: The coal chemical industry has made an important contribution to the development of the national economy. However, the problem of coking wastewater pollution can not be ignored. The annual discharge of coal chemical coking wastewater in China is as high as several hundred million tons. These wastewater pollution hazards and toxicity are large, High concentration, the impact of large. This paper mainly analyzes the pollution control measures of coking wastewater in coal chemical industry.

Key words: coal chemical industry; coking wastewater; pollution control measures

Coal chemical industry is an important industry in our country, but a large amount of wastewater will be discharged during the production process. These wastewater have greater pollution. In order to control pollution, we must adopt targeted prevention and control measures for each step in coal chemical production. For now, there are still a series of problems in the control of China's coal chemical coking wastewater pollution, the following analysis on this issue.

1 coal chemical coking wastewater pollution hazards

In the current coal chemical industry, coking wastewater pollution is very serious, each year China's coal chemical coking wastewater displacement of up to hundreds of millions of tons of pollution hazards of these wastewater, toxic, high concentration, a wide range of influence. In addition, coking wastewater has a lot of ammonia nitrogen compounds, but also adversely affect the ecological environment. Coal chemical production process will involve cyanide, sulfur, nitrogen and other chemical substances, after treatment, will generate all kinds of toxic substances, common halogenated hydrocarbons, polycyclic aromatic hydrocarbons, etc., the treatment of hazards is very difficult.

2 coal chemical industry coking wastewater pollution control technology

2.1 Physico-chemical pretreatment method

For coal chemical coking wastewater, pretreatment is very important. Due to the complex water quality of these wastewater, pretreatment measures must be taken according to the water quality to ensure that the water quality can meet the follow-up requirements. The specific pretreatment methods include steaming, phenol removal , Degreasing, the degradation of toxic substances and so on. If the concentration of some substances in the wastewater is too high, there will be neurotoxicity. If a chemical coking wastewater phenol, H2S, NH3 content is higher, you can use the twin towers steam to remove most of them H2S, NH3. In order to improve the biodegradability of coking wastewater, it needs to decompose and remove the macromolecules in advance. Some researchers use cyclohexane and n-octanol as extractants, and adopt biological treatment method to improve COD removal rate. Another researcher on the coking wastewater organic expansive soil for processing, played a good role in adsorption, increased B / C value.

2.2 biological treatment method

Biological treatment of environmental protection, simple, has been in the treatment of coal chemical coking wastewater plays an important role, representative of UASB, SBR, A / O and so on.

In the coal chemical coking wastewater, there are a lot of phenol, ammonia nitrogen and COD, many of the material is difficult to degrade, in order to achieve the desired effect, we must implement biological treatment. Biological treatment of coal chemical coking wastewater generally use A / O method, in order to strengthen the treatment effect, the need to strengthen the selection of bacteria on this basis, the use of efficient bacteria and microbial reactors. About biological treatment, from the content point of view includes three aspects: the structure and function of key bacteria. Its main is the study of microorganisms as the core.

2.3 depth treatment method

Coking wastewater in coal chemical industry has a large number of refractory substances, after the application of biological treatment, there are still some substances can not be degraded, therefore, must be dealt with in depth. Depth treatment is to promote wastewater standards to take a series of advanced treatment measures, such as adsorption, coagulation, advanced oxidation. Coking wastewater with multi-level pollution, these substances change range is too large. With conventional approaches, it is difficult to fully identify the inherent water quality characteristics. Sewage in the phenols, corresponding to the inherent high levels of ammonia nitrogen substances, after initial pretreatment, biodegradable. However, polycyclic aromatic hydrocarbons and less than the ratio of two VA Ying, all kinds of halogenated hydrocarbons with higher toxicity of this type, but also lurk a wider range of ecological threats. In the process of treatment, they inhibit the conventional role of microorganisms. This unique composition of COD highlights the necessary value. Deep-processing techniques should consider the necessary suspended components, corresponding to colloidal components, with dissolution characteristics of such components. Partial inorganics with reduction properties are also covered.

3 coal chemical industry coking wastewater pollution treatment development direction

Although the coking wastewater treatment technology in coal chemical industry has matured, there are still some shortcomings. In the next stage, we should further improve the pretreatment process, reform the existing steam ammonia, phenol removal, oil removal technology, and strengthen the pretreatment , Improve the biodegradability of coking wastewater, provide convenience for subsequent biological treatment, reduce the burden of deep treatment and reduce the treatment cost. Hydrolysis acidification is a good way to handle operability and economy. Some scholars use the hydrolysis MBR process for processing, the results show that after the hydrolysis acidification section treatment 5h, the wastewater CODCr / BOD5 rose from the previous 0.11 to the later 0.31, the system is also more stable. In addition, the composition of coking wastewater is complex, in the next stage, should take advantage of dominant bacteria and a new reactor to improve the treatment effect. In the choice of advanced treatment process, it can be decided according to water quality and emission standard. If the advanced treatment effect is better, the follow-up treatment method may not be adopted and the follow-up treatment method is convenient. Further development of efficient coagulation and sedimentation technology is needed, and a low-cost Regeneration of adsorbent, to solve the high cost, economic performance is not ideal problem.

4 Conclusion

Coal chemical industry coking wastewater has a lot of toxic substances, the harm is very large, for coal chemical coking wastewater treatment, the need for in-depth analysis of its composition and processing requirements, according to the specific circumstances to take appropriate treatment technology. Strengthen the analysis of the composition of coal chemical coking wastewater under various environmental conditions, assess the safety of wastewater and enhance the effect of pollution treatment.

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