A method and system for recovering salt from a wastewater treatment system

Abstract

The invention discloses a method for recovering salt from a waste water treatment system. The waste water is subjected to primary treatment by virtue of the processes such as oxidation, adsorption, precipitation, filtration, softening and CO2 removal in the steps (1) to (5); the running influence factors and effects of RO (reverse osmosis) in the step (6) are removed; meanwhile, the purity of subsequently extracted nitrate and salt is ensured; a set of step-by-step nitrate and salt separation process of warming, cooling and warming is provided in the steps (7) to (11); the extracted nitrate and salt are ensured to meet the purity requirements; and meanwhile, the processed liquid waste is subjected to secondary treatment. The invention also discloses a system for a process for recovering salt from the waste water treatment system. An energy conversion unit is arranged in the system; the heat in the nitrate and salt extracting processes is mutually converted and used; the energy utilization rate is increased; and resources are saved to the maximal limit.

Description

technical field [0001] The invention relates to a method and system for recovering salt from a waste water treatment system, which can separate and purify industrial salt while removing harmful substances in the waste water, and is especially suitable for the treatment of coal chemical sewage, belonging to energy saving and emission reduction and waste The field of recycling. Background technique [0002] With the continuous construction of industrial production facilities, the amount of sewage, waste gas, and waste discharge is also increasing, and the environmental tolerance and discharge allowance are getting smaller and smaller, so zero-emission systems are also being promoted. The requirements for zero emissions in the production process of large industries are also getting higher and higher. For example, if the construction of a large-scale project with more than 1 million tons of methanol and its subsidiary coal-to-acetic acid, ethylene glycol, and coal-to-olefins, if...

AI Technical Summary

Problems solved by technology

[0005] 1. The quality of raw water is high, and the content of sodium sulfate needs to be strictly controlled and kept constant, generally at 3-10%. When the content of sodium sulfate is high, the separation process is more complicated, and it is necessary to repeatedly adjust the temperature and concentration of wastewater to separate different salts. And the recovered salt is impure and contains more impurities;

[0006] 2. High requirements for external water, electricity, steam and temperature control, if a certain condition changes, it may lead to uneven separation and purification;

[0007] 3. It is difficult to operate and adjust, and there is room for improvement in evaporation heat efficiency, resulting in increased waste of resources and cost

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