Treatment method of high-salt content, high-ammonia nitrogen content and high-COD (Chemical Oxygen Demand) gas field water

Abstract

The invention discloses a treatment method of high-salt content, high-ammonia nitrogen content and high-COD (Chemical Oxygen Demand) gas field water and belongs to the field of wastewater treatment processes. The treatment method comprises the following steps of: firstly removing calcium, magnesium and suspended matters in the gas field water, and regulating the pH value to be above 10; then performing staged evaporation, namely adopting primary feeding batch operation for the first stage of evaporation; performing the second stage of evaporation on concentrated liquid, namely adopting vacuum evaporation for the second stage of evaporation; thickening salt slurry discharged in the second stage of evaporation, and then washing, dewatering and drying to obtain a salt product; performing electrolytic and catalytic oxidation on mother liquor discharged in the second stage of evaporation for removing COD, and returning the treated mother liquor as well as mother liquor obtained by thickening with the salt slurry to the gas field water for reuse, wherein the second stage of condensate water obtained in the second stage of evaporation is water reaching the standards, and after the first stage of condensate water obtained in the first stage of evaporation is treated, subjected to ammonia nitrogen removal and mixed with the second stage of condensate water, water reaching the standards is obtained. According to the treatment method disclosed by the invention, the problems of low possibility of removing salt, ammonia nitrogen and COD in the high-salt content, high-ammonia nitrogen content and high-COD sulfur-containing natural gas field produced water in the prior art can be solved.

Description

technical field [0001] The invention belongs to the field of sewage treatment technology, and in particular relates to the treatment of produced water from sulfur-containing natural gas fields with high salt content, high ammonia nitrogen content and COD. Background technique [0002] Due to the long-term coexistence with underground oil and gas reservoirs and rock formations, the produced water of natural gas fields is generally dissolved or mixed with a large amount of components such as petroleum, soluble salts, and suspended solids. In addition, in the process of gas production and gathering and transportation, it is often necessary to add chemical additives such as foaming agents, corrosion inhibitors, and scale inhibitors, which makes the composition of the produced water in natural gas fields more complex and varied, and shows high oil content, volatile It has the characteristics of high organic matter content, high suspended matter content and high mineralization deg...

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Problems solved by technology

[0004] Generally speaking, the membrane method and ion exchange method have a good treatment effect on the produced water of non-sulfur gas fields with relatively simple water quality. For the produced water of sulfur-containing gas fields, the membrane is easily polluted, and the ion exchange resin regeneration is difficult, and the membrane separation concentrate or ion exchange resin regeneration liquid still needs to be further treated in a harmless manner, resulting in a significant increase in its treatment and operating costs , so it is limited in industrial application

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