Salt separation process wastewater treatment system

Abstract

The utility model provides a salt separation process wastewater treatment system, and relates to the technical field of wastewater treatment. The device comprises a dosing unit, a sodium sulfate salt recovery unit and a sodium chloride salt recovery unit, the sodium sulfate salt recovery unit comprises freezing feeding tanks which are communicated in sequence, and the sodium chloride salt recovery unit comprises triple-effect feeding tanks which are communicated in sequence. Wastewater pre-concentrated by the salt separation device pre-concentration MVR system is input into the freezing feeding tank, wastewater output by the salt separation device sodium chloride system is input into the triple-effect feeding tank, and the dosing unit comprises a sodium hypochlorite dosing pump communicated with the freezing feeding tank and the triple-effect feeding tank. And the sodium hypochlorite dosing pump is used for dosing sodium hypochlorite into the freezing feeding tank and the triple-effect feeding tank. According to the utility model, the COD removal rate is improved, and the chromaticity and viscosity of wastewater are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of wastewater treatment, in particular to a wastewater treatment system for a salt separation process. Background Art

[0002] Salt separation treatment is the terminal system for zero discharge of wastewater. The purpose is to evaporate and recycle the water in the wastewater, and separate the salts in the water in the form of single salts (such as sodium chloride and sodium sulfate salt separation devices). The single salts can be sold as by-products. In the prior art, the salt separation device operates in a continuous evaporation and concentration process. During the evaporation process, it continuously concentrates and aggregates. The concentration of the water at the end of the device is the highest, and the COD of the wastewater at the back end of the evaporation treatment is as high as 50,000 mg / L. Affected by COD during this concentration process, the adverse effects include foaming in the system, high conductivity of the recovered condensate water and inability to recycle it, yellowing of the by-product salt sodium chloride, and high viscosity of the terminal wastewater and easy blockage of pipelines.

[0003] However, at present, there is no effective method for removing COD from high-salt wastewater. Microorganisms in biochemical treatment cannot adapt to wastewater with a salt content of 70,000 mg / L and cannot degrade COD through biochemical treatment. The COD removal rate of advanced oxidation equipment is relatively low, with an average removal rate between 20% and 40%. The operation is complex and the COD removal is not thorough. Summary of the Utility Model

[0004] The purpose of the utility model is to develop a wastewater treatment system for a salt separation process that can improve the COD removal rate, reduce the chromaticity and viscosity of wastewater.

[0005] The utility model is realized through the following technical solutions:

[0006] A wastewater treatment system for a salt separation process, comprising:

[0007] A dosing unit, a sodium sulfate salt recovery unit and a sodium chloride salt recovery unit;

[0008] Among them, the sodium sulfate salt recovery unit includes a freezing feed tank connected in sequence, and the sodium chloride salt recovery unit includes a triple-effect feed tank connected in sequence. The wastewater pre-concentrated by the pre-concentration MVR system of the salt separation device is input into the freezing feed tank, and the wastewater output from the sodium chloride system of the salt separation device is input into the triple-effect feed tank;

[0009] The dosing unit includes a sodium hypochlorite dosing pump connected to the freezing feed tank and the triple-effect feed tank. The sodium hypochlorite dosing pump adds sodium hypochlorite to the freezing feed tank and the triple-effect feed tank.

[0010] Optionally, the dosing unit further includes a sodium hypochlorite unloading pump and a sodium hypochlorite storage tank connected to each other, and the sodium hypochlorite dosing pump is connected to the sodium hypochlorite storage tank.

[0011] Optionally, the sodium hypochlorite dosing pump is a frequency conversion metering pump controlled by DCS.

[0012] Optionally, the sodium sulfate recovery unit further includes a freeze crystallizer and a centrifuge that are connected in communication, and the freeze feed tank is in communication with the freeze crystallizer.

[0013] Optionally, the sodium chloride recovery unit includes a triple-effect evaporator and a centrifuge that are connected in communication, and the triple-effect feed tank is in communication with the triple-effect evaporator.

[0014] Optionally, a pH on-line detector is provided in the freeze feed tank and the triple-effect feed tank, and the pH on-line detector is interlocked with the sodium hypochlorite dosing pump for control.

[0015] Optionally, chlorine gas alarm probes are provided in the freeze feed tank and the triple-effect feed tank.

[0016] Optionally, vent pipes are connected to both the freeze feed tank and the triple-effect feed tank.

[0017] The beneficial effects of the present utility model are as follows:

[0018] In the salt separation process of the present utility model, adding sodium hypochlorite achieves the purpose of reducing the COD in the wastewater. The removal rate of COD reaches more than 70%, and the chromaticity and viscosity of the wastewater are reduced, turning the yellow-brown wastewater into colorless, improving the whiteness of sodium chloride and sodium sulfate salts, and reducing the frequency of pipeline blockages. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 It is a system structure diagram of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the drawings and the description are considered to be exemplary in nature rather than restrictive.

[0022] The embodiments of the present utility model will be described in detail below with reference to the drawings.

[0023] As Figure 1As shown in the figure, the utility model discloses a wastewater treatment system for salt separation process, which includes a dosing unit, a sodium sulfate recovery unit and a sodium chloride recovery unit. The dosing unit adds sodium hypochlorite to the sodium sulfate recovery unit and the sodium chloride recovery unit.

[0024] The sodium sulfate recovery unit includes a freezing feed tank, a freezing crystallizer and a centrifuge connected in sequence. After the wastewater is pre-concentrated by the pre-concentration MVR system of the salt separation device, the wastewater is input into the freezing feed tank.

[0025] The sodium chloride recovery unit includes a triple-effect feed tank, a triple-effect evaporator and a centrifuge connected in sequence. The wastewater output from the sodium chloride system of the salt separation device enters the triple-effect feed tank.

[0026] The dosing unit includes a sodium hypochlorite unloading pump, a sodium hypochlorite storage tank and a sodium hypochlorite dosing pump connected in sequence. The sodium hypochlorite dosing pump puts sodium hypochlorite into the freezing feed tank and the triple-effect feed tank.

[0027] Both the freezing feed tank and the triple-effect feed tank are equipped with a pH on-line detector and a chlorine gas alarm probe. The top of the freezing feed tank and the triple-effect feed tank are both equipped with vent pipes extending to the outside. The pH on-line detector is interlocked with the sodium hypochlorite dosing pump and a low pH alarm value is set. When the pH reaches the low alarm value, the sodium hypochlorite dosing pump stops dosing.

[0028] The sodium hypochlorite storage tank is made of a material that cannot be penetrated by light. The sodium hypochlorite dosing pump is a variable-frequency metering pump controlled by DCS. The dosing amount of sodium hypochlorite is based on the COD and flow rate of the incoming wastewater. The dosing amount of sodium hypochlorite in the wastewater is 30 - 50 ppm.

[0029] The COD in the wastewater pre-concentrated by the pre-concentration MVR system of the salt separation device and the wastewater output from the sodium chloride system of the salt separation device reaches 15,000 mg / L. After the wastewater enters the triple-effect feed tank and the freezing feed tank, the sodium hypochlorite dosing pump adds sodium hypochlorite to the triple-effect feed tank and the freezing feed tank. By using the strong oxidizing property of the nascent oxygen generated after the hydrolysis of sodium hypochlorite, the macromolecular organic matter is oxidized into small molecular organic matter, removing COD and effectively removing the organic matter in the wastewater, thereby reducing the viscosity and chromaticity. Since chlorine gas will be generated when sodium hypochlorite hydrolyzes in an acidic environment, the pH is controlled to be > 8 by the set pH on-line detector, and the set chlorine gas alarm probe alarms after detecting chlorine gas.

[0030] The wastewater output from the triple-effect feed tank and the freezing feed tank are respectively subjected to triple-effect evaporation and freezing crystallization, and then are respectively fed into a centrifuge to separate out sodium chloride salt and sodium sulfate salt.

[0031] In the salt separation process of the present utility model, adding sodium hypochlorite is adopted to achieve the purpose of reducing the COD in wastewater. The removal rate of COD reaches over 70%, and the chromaticity and viscosity of the wastewater are reduced, turning the yellowish-brown wastewater into colorless, improving the whiteness of sodium chloride and sodium sulfate, and reducing the frequency of pipeline blockage.

[0032] The above embodiments are only the preferred embodiments of the present utility model, and do not limit the technical solutions of the present utility model. Any technical solutions that can be achieved on the basis of the above embodiments without creative labor shall be regarded as falling within the scope of the patent rights of the present utility model.

Claims

1. A wastewater treatment system for salt separation process, characterized in that It includes: A chemical dosing unit, a sodium sulfate salt recovery unit and a sodium chloride salt recovery unit; Among them, the sodium sulfate salt recovery unit includes a freezing feed tank connected in sequence, and the sodium chloride salt recovery unit includes a triple-effect feed tank connected in sequence. The wastewater pre-concentrated by the pre-concentration MVR system through a salt separation device is input into the freezing feed tank, and the wastewater output from the sodium chloride system of the salt separation device is input into the triple-effect feed tank; The chemical dosing unit includes a sodium hypochlorite dosing pump connected to the freezing feed tank and the triple-effect feed tank, and the sodium hypochlorite dosing pump adds sodium hypochlorite to the freezing feed tank and the triple-effect feed tank.

2. The salt separation process wastewater treatment system according to claim 1, characterized in that The chemical dosing unit further includes a sodium hypochlorite unloading pump and a sodium hypochlorite storage tank connected to each other, and the sodium hypochlorite dosing pump is connected to the sodium hypochlorite storage tank.

3. The wastewater treatment system for salt separation process according to claim 1, characterized in that, The sodium hypochlorite dosing pump is a variable-frequency metering pump controlled by DCS.

4. The salt separation process wastewater treatment system according to claim 1, characterized in that, The sodium sulfate salt recovery unit further includes a freezing crystallizer and a centrifuge connected to each other, and the freezing feed tank is connected to the freezing crystallizer.

5. The salt separation process wastewater treatment system according to claim 1, wherein The sodium chloride salt recovery unit includes a triple-effect evaporator and a centrifuge connected to each other, and the triple-effect feed tank is connected to the triple-effect evaporator.

6. The wastewater treatment system for salt separation process according to claim 1, wherein PH on-line detectors are provided in the freezing feed tank and the triple-effect feed tank, and the PH on-line detectors are interlocked with the sodium hypochlorite dosing pump for control.

7. The salt separation process wastewater treatment system according to claim 1, wherein Chlorine gas alarm probes are provided in the freezing feed tank and the triple-effect feed tank.

8. The salt separation process wastewater treatment system according to claim 1, wherein Vent pipes are connected to both the freezing feed tank and the triple-effect feed tank.

Images