Device and method for treating methanol-to-olefin waste alkali solution

Abstract

The invention discloses a device and a method for treating a methanol-to-olefin waste alkali solution. The treatment device comprises a pH regulating tank, an oil separator, a bioreactor and a settling pond which are sequentially connected through pipelines, wherein the settling pond is connected with the bioreactor through a sludge return pipe. The treatment method disclosed by the invention adopts the previous device and comprises the steps of pH regulation, oil separation, microbe decomposition and settling treatment. The treatment device of the waste alkali solution during methanol-to-olefin production is simple in structure and low in cost; compared with the traditional burning method, wet oxidation process and other waste alkali solution treatment process flows, the method disclosed by the invention is short in flow and low in equipment investment and operating cost, one-time investment and comprehensive system operating treatment cost are reduced, and the method is implemented under normal temperature and normal pressure conditions. Moreover, a high-temperature high-pressure operating mode existing in the burning method, the wet oxidation process and the like is avoided, potential risk factors are eliminated, pollutants are not transferred, secondary pollution is avoided, and the method is an environmental-friendly process technology in a real sense.

Description

technical field [0001] The invention belongs to the field of wastewater treatment, and in particular relates to a treatment device and method for waste lye in the production process of methanol to olefins. Background technique [0002] The waste caustic liquor produced by methanol to olefins (MTO for short) comes from the olefin separation process of the methanol to olefins unit. This process uses fresh liquid caustic soda to absorb acid gases such as carbon dioxide and hydrogen sulfide produced during the olefin separation process, and finally forms a large amount of spent caustic soda liquid. Sodium hydroxide 1.5%, sodium carbonate 10.5%, water 88% in waste lye, phenol concentration in organic pollution 50mg / l, methanol concentration 260mg / l, also contain a small amount of benzene, ethylbenzene, toluene, dimethyl ether, ethyl Ketone, methyl ethyl ketone, etc., the main pollutant indicators COD10000mg / l, TOC2000-6000mg / l, ammonia nitrogen 50mg / l. [0003] The methanol-to-...

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Problems solved by technology

[0003] The methanol-to-olefins process technology has become increasingly mature in recent years, but the waste lye produced during the production process is difficult to treat due to its high salt content, strong alkalinity, and high organic matter concentration, which is a major environmental protection problem affecting the development of methanol-to-olefins technology

In the methanol-to-olefins plant that was put into operation in the past few years, some enterprises used incineration, wet oxidation and other methods to treat the waste lye. The above-mentioned treatment methods mainly have the following problems: 1) large-scale equipment investment; 2) high operating costs; 3 ) The operation process is carried out under high temperature and high pressure conditions, which requires high equipment materials and safety performance; 4) The treatment process is easy to cause blockage of pumps and pipelines; 5) The removal efficiency of organic matter is low, and the treated wastewater is easy to be used by subsequent The operation of the sewage plant caused an impact

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