System and method for treating sewage containing salt

Abstract

The invention discloses a system and method for treating sewage containing salt. The system comprises a pretreating unit, a pre-concentrating unit, an evaporating unit, a crystallizing unit, a condensate fine treating unit and a solid ingredient treating and recycling unit. When pretreating is carried out, the sewage which is to be treated and contains salt is introduced, and waste water and sludge are generated after treatment; pure water and concentrated water are generated in the pre-concentrating process; condensate and strong brine are generated in the evaporating process; condensate and crystallized salt are generated in the crystallizing process, the pure water and the condensate are subjected to a condensate fine treating process, and the sludge and crystallized salt are subjected to a solid ingredient treating and recycling process; recycling water is generated in the condensate fine treating process. By means of the system, customized process selection can be carried out according to different demands, swage discharge to an adjacent water body can be completely eliminated, moisture can be recycled to the maximum degree, high-purity softened water can be obtained to the maximum degree, energy consumption is low, and resource recycling of the salt can be achieved.

Description

technical field [0001] The present invention relates to the field of sewage treatment, in particular, relates to a salt-containing sewage used in oil refining, petrochemical salt-containing sewage, coal chemical industry salt-containing sewage, power plant flue gas desulfurization sewage, circulating water discharge sewage, mining sewage, and oil and gas production water A zero-discharge treatment system and method, etc., belong to the field of industrial sewage treatment. Background technique [0002] At present, problems such as shortage of water resources, poor water environment quality, and serious damage to water ecology in some areas of our country are very prominent, which is not conducive to sustainable economic and social development. According to statistics, industrial water intake accounted for about 25% of the country's total water intake in 2013, of which thermal power, steel, textile, papermaking, petrochemical and chemical industries accounted for about 50% of...

AI Technical Summary

Problems solved by technology

In the above-mentioned existing treatment systems, the pretreatment mainly adopts the conventional coagulation sedimentation + softening and dehardening + filtration process. This pretreatment process has low treatment effect, high energy consumption, and takes up a large area. The most important thing is that it does not remove the high COD process measures, resulting in serious fouling of the downstream membrane concentration unit and evaporation crystallization unit, poor salt quality, it is difficult to ensure the stable operation of the downstream unit; the commonly used high-efficiency reverse osmosis membrane concentration unit requires high chemical cleaning frequency and As a result, the net water production rate decreased, the frequency of membrane replacement was high, and the operating cost was high; evaporation and crystallization mainly produced mixed salt, and it was impossible to truly separate high-quality industrial-purity elemental salt, and failed to achieve resource recovery and utilization of elemental salt. The cost of landfill disposal is high; the condensate produced by the system still contains high COD, ammonia nitrogen, etc., and cannot be directly reused as process water

Images