Recycling and harmless treatment method and system for salt in high-salt-content wastewater

Abstract

The invention provides recycling and harmless treatment method and system for salt in high-salt-content wastewater. The treatment method comprises the following steps: enabling the high-salt-content wastewater to enter a nanofiltration device, and adding sulfuric acid into the nanofiltration device to enable nanofiltration to operate in a neutral state; collecting produced water on the water production side of the nanofiltration device and re-concentrating the produced water to obtain a concentrated sodium chloride solution; collecting sodium sulfate on the concentrated water side of the nanofiltration device, crystallizing the sodium sulfate, and collecting crystallized first mother liquor; and evaporating and concentrating the concentrated sodium chloride solution to reach a saturated concentration, and separating out sodium chloride crystals to obtain a second mother solution; then mixing the first mother liquor and the second mother liquor, evaporating and crystallizing the mixtureto obtain mixed salt of inorganic salt and organic matters; conveying the mixed salt to a harmless treatment area, heating the mixed salt through a plasma torch for decomposing organic matters in themixed salt into combustible flue gas, and performing gas treatment to obtain inorganic salt. According to the method, organic matters in the mixed salt can be removed, so that the mixed salt is not necessary to be treated according to hazardous wastes.

Description

technical field [0001] The invention relates to the technical field of waste water zero discharge and salt separation and crystallization, in particular to a method and system for resourceful and harmless treatment of salt content in high-salt waste water. Background technique [0002] With the increasingly serious environmental problems, environmental protection and pollution treatment have received more and more attention. Among them, wastewater treatment in the fields of coal chemical industry wastewater and pharmaceutical chemical industry has always been the top priority. At present, the wastewater reuse technology has matured and stabilized, realizing the reduction of wastewater, but the disposal of high-salt wastewater after membrane concentration has become one of the most difficult wastewater to treat in China. [0003] The high brine produced in the process of wastewater reuse treatment, after membrane concentration treatment, the organic matter in the wastewater ...

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Problems solved by technology

[0004] However, evaporation and crystallization will eventually produce a certain amount of mother liquor, and miscellaneous salts obtained by evaporation and other means are included in the list of hazardous wastes by the Ministry of Environmental Protection. Continuous accumulation and storage will lead to serious environmental hazards and pollution risks. Once diffused and leached out, there will be It has caused huge environmental pollution incidents, and at the same time, the status quo that most enterprises have accumulated a large amount of waste salt and cannot handle it has also brought great environmental pressure to the enterprises themselves.

According to incomplete statistics, the annual output of industrial waste salt in the country reaches tens of millions of tons. The cost of disposal as hazardous waste is quite high, and the environmental protection costs of enterprises will not be able to bear it. Most enterprises currently produce miscellaneous salt are stored in factory warehouses. Wait for the technology to mature for further processing

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