Low-cost water treatment and recycling method for high-salinity gas field

Abstract

The invention belongs to the technology of electrodialysis desalination, in particular to a low-cost water treatment and recycling method for a high-salinity gas field. The salt in the wastewater andCOD wastewater in the water of the high-salinity gas field are separated through electrodialysis; the salt easy to form a scale in the wastewater is subjected to double decomposition to form a solublesalt; the mixed salt in the wastewater is salted out and concentrated through monovalence and bivalence selective electrodialysis; the salt water extracted through the above method is further subjected to membrane distilling, mechanical steam recompression, or multiple-effect evaporation, concentration and crystallization to recycle the industrial salt, the COD in the extracted COD wastewater isfurther removed through a biochemical process, and then the wastewater is recycled and discharged. In the process, that the salt recycled by directly using membrane distilling, mechanical steam recompression, or multiple-effect evaporation, concentration and crystallization cannot be sold due to high organic content, can be avoided, the condition that the recycled salt is the mixed salt and becomes a solid waste is avoided, and the defect that the salinity is too high to affect the stable operation of a biochemical system is also avoided. The method not only solves the problem of wastewater, but also recycles the water and the salt in the wastewater, and the application potential is huge.

Description

technical field [0001] The invention belongs to the electrodialysis desalination technology, in particular to a low-cost treatment and resource utilization method for high-salt gas field water. Background technique [0002] Gasfield water is the formation water brought out from the gas well along with the natural gas during the natural gas production process and the condensed water produced during the gas gathering and production process. The composition of gas field water in different regions varies greatly. Even in the same gas field, the water quality and quantity of gas field water vary greatly at different times. Generally, the salinity is tens of thousands to hundreds of thousands mg / L, and the COD value is tens to Several thousand mg / L. [0003] Gas field water reinjection is currently the main treatment method, which includes coagulation, filtration and fine filtration units. Water reinjection wells in gas fields need to meet the following conditions: (1) large wat...

AI Technical Summary

Problems solved by technology

[0011] To sum up, the salinity of gas field water is very high, and the COD value is tens to several thousand mg / L, making it increasingly difficult to find suitable reinjection wells; and the large amount of mixed salt produced by evaporation and crystallization can basically only be filled However, it is difficult to use alkali, carbonate and sulfate to remove calcium and magnesium ions due to the high concentration of calcium and magnesium ions, and too much slag is produced. Catalytic oxidation, potassium permanganate, sodium hypochlorite, Fenton and other oxidations face the limitation of high cost.

As the requirements for environmental protection become more and more stringent, the treatment of gas field water has become an unfavorable factor restricting the development of natural gas mining enterprises, affecting the development of new gas fields and even the production of established gas fields

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