Method for oil removal from wastewater in field of coal chemical industry

Abstract

The invention discloses a method for oil removal from wastewater in the field of coal chemical industry, which is characterized in that oil contains soluble oil; and the method comprises the following steps: wastewater pretreatment, extraction and oil removal, and extraction agent recovery. Through the method, the oil contained in the wastewater, in particular to the soluble oil can be effectively removed. The invention further provides normal hexane and / or petroleum ether as an extraction agent; and through a practical application experiment, after the method is adopted, the oil contained in the treated wastewater is the soluble oil basically, the removal rate of the oil reaches 95.31-97.91 percent, and the removal rate of the soluble oil reaches 87.08-94.17 percent, so that a good oil removal effect is reached, and particularly, the effect of removing the soluble oil is good.

Description

Technical field [0001] The invention belongs to the technical field of coal chemical wastewater treatment, and specifically relates to a method for removing oil from wastewater in the coal chemical industry. technical background [0002] In the deep processing of coal gasification, liquefaction to oil, combustion power generation, coking, etc., a large amount of highly polluting wastewater is inevitably produced. These wastewater contains a large amount of pollutants such as oil, ammonia, and acid gas, which can only be removed after purification. After the oil is removed, it can be further deacidified, ammoniated, and phenol removed. Finally, advanced treatment such as biochemical treatment can be carried out to meet the emission requirements. At the same time, the oil contained in the water can be recovered to realize its value. [0003] The oily substances in the coal chemical wastewater mainly have the following occurrence states: (1) floating oil (particle size> 100μm), eas...

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Problems solved by technology

[0004] The existence of oily wastewater is a huge hazard, which seriously restricts the further purification of this kind of wastewater, and during its discharge, it will settle in the pipeline together with other suspended solid particles and scale in the water, eventually forming a highly viscous The oily sludge will affect the normal production and even block the pipeline

In addition, if the oil contained in the wastewater cannot be effectively removed, it will also affect the further treatment of the wastewater, such as the extraction and recovery of phenol, and the biochemical treatment of wastewater also has strict requirements on the oil content in the water

[0005] Conventional oil removal methods include coagulation sedimentation method, air flotation method, coarse particle method and filtration method. Although these treatment methods are mature, they all have different shortcomings: (1) In the process of water body purification, coagulation sedimentation method The method needs to add a chemical coagulant, while the air flotation method needs to add a flotation agent. Although the two processes can remove oil in water, they produce sludge and scum that are more difficult to handle; (2) The coarse particle method does not need to add other (3) Although the flotation method is convenient in production and management and low in cost, it can only remove floating oil, dispersed oil and emulsified oil, but not Soluble oil; (4) The filtration method is generally used as a further purification step after oil-water separation. During the implementation process, the filter material is easy to clog, and air backwashing and hot water backwashing are required at this time, which increases the difficulty and cost of management. Cost, maintenance cost, operating cost and other issues need to be considered; (5) In the existing process methods, no matter which of the above methods, it is impossible or difficult to remove the dissolved oil in the water, and the dissolved oil directly affects the normal operation of the next process

[0006] 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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