A method for deoiling and dephenolizing waste water in the field of coal chemical industry

Abstract

The invention discloses a method for oil and phenol removal from wastewater in field of coal chemical industry. The method is characterized in that in the wastewater containing oil and phenol generated in the coal chemical industry process, as the oil mostly is soluble oil, through combining wastewater pretreatment, extraction and oil and phenol removal and extraction agent recovery with related processes, a good oil and phenol removal effect is achieved, and the content of the soluble oil is effectively reduced. The invention further provides an extraction agent cyclohexane; and through a site test, the oil removal rate reaches 94.71-97.30 percent, the oil removal rate of the soluble oil reaches 87.08-92.81 percent, and the phenol removal rate reaches 96.94-98.21 percent, therefore, the effect is remarkable.

Description

technical field [0001] The invention belongs to the technical field of coal chemical wastewater treatment, and in particular relates to a method for deoiling and dephenolizing wastewater in the coal chemical industry. technical background [0002] During the utilization of coal such as coal gasification, liquefaction to oil, combustion power generation, coking, coal pyrolysis, etc., a large amount of highly polluted wastewater is inevitably produced, which contains a large amount of oil, ammonia, phenol and other pollutants , Only after purification, oil removal and phenol removal, can further advanced treatment such as biochemical treatment meet the emission requirements, and at the same time, the oil and phenol contained in the water can be recovered to realize its value. [0003] Oily substances in wastewater mainly have the following states of occurrence: (1) floating oil (particle size > 100 μm), which is easy to separate from wastewater; (2) dispersed oil (particle ...

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Problems solved by technology

[0005] Wastewater rich in oil / phenol is a huge hazard and seriously pollutes the environment

Moreover, once the wastewater is discharged, the oil will float on the water surface and quickly spread to form an oil film, cutting off the source of oxygen in the water body and adversely affecting the growth of aquatic organisms.

During its discharge, the oil will settle in the pipeline together with other suspended solid particles and scale in the water, and finally form a highly viscous oil sludge mass, which will affect the normal production and even block the pipeline

[0006] In addition, phenol in wastewater is a kind of protoplasmic poison, directly discharged into water will not only endanger the reproduction and survival of aquatic organisms, but also increase the BOD value

The harm of high concentrations of phenols to crops is manifested in the inhibition of photosynthesis and enzyme activity, the hindrance of cell functions, and the destruction of auxin formation, etc., and will lead to an increase in the content of phenols in organisms, affecting the quality of crop products

[0007] Conventional wastewater treatment methods can only remove oil or phenol alone, and cannot meet the requirements of oil removal and / or phenol removal by a single method, especially the removal of soluble oil and / or phenol

Although these methods are mature, they still have different disadvantages: (1) The container containing oily wastewater is rotated at high speed to achieve the purpose of oil-water separation by centrifugal force. The separation equipment of this method is small in size and high in oil removal efficiency, but the high flow rate produces The turbulent flow is easy to disperse and cut parts, and the operating cost is high, the amount of water to be treated is small, and it has no effect on soluble oil; (2) The electroflocculation method has the advantages of good treatment effect, small footprint, and simple operation, but At the same time, there are also disadvantages such as large anode metal consumption, anode passivation, need for a large amount of salts as auxiliary agents, high power consumption, etc., and have no effect on soluble oil; (3) Filtration method is generally used for secondary treatment or advanced treatment of oil in wastewater quality, the method is simple in equipment, easy to operate, and needs to be backwashed. If the management is not good, it is easy to cause blockage of the filter material and has no effect on the dissolved oil; (4) The method of using strong high-temperature steam to heat phenol-containing wastewater is steam dephenolization This method is mainly used for the treatment of high-concentration volatile phenols. The quality of recovered phenols is good and does not bring other pollution, but the steam consumption is too large, and only low-boiling point phenols can be removed, and the effect of removing phenols is not ideal; (5) Biochemical method is a conventional method for dephenolizing wastewater, but the process has certain requirements on the concentration of water temperature and organic matter (such as oil content, phenol content, etc.), especially the content of organic matter must be controlled in a low range, such as oil content less than 50mg / L. The phenol content is less than 400mg / L, otherwise the microorganisms will die; (6) Activated sludge removal of phenol is a wastewater treatment method based on activated sludge. The impact is small, etc., but it requires high pretreatment, high operating expenses, and also has certain requirements for the concentration of organic matter (such as oil content, phenol content, etc.)

(7) None of the existing processes can meet the requirements of oil removal and / or phenol removal by a single method

[0008] With the increasing complexity of the coal chemical process in recent years, the soluble oil content in the coal chemical wastewater is getting higher and higher. Although the existing oil removal technology has a good oil removal effect, it cannot remove the soluble oil. People stick to the traditional mature However, insufficient attention has been paid to the removal of soluble oils, and there are basically no methods for such problems

In addition, although in order to remove soluble oil, people may think of selecting some extractants according to the needs, but as a multi-component complex system with a large amount of treatment, it is impossible to rely solely on the known characteristics of the extractants. Solve the problem of soluble oil removal in coal chemical industry wastewater

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