CN204529576U - A kind of process recovery system of organic high-salt wastewater - Google Patents

Abstract

The utility model discloses a treatment and recovery system for organic high-salt wastewater, which comprises a vibrating membrane filtration unit, a vibrating membrane concentrating unit connected with the outlet water of the vibrating membrane filtering unit, and a vibrating membrane concentrating unit connected with the vibrating membrane concentrating unit. The effluent is connected to the MVR evaporation unit. The treatment steps include: 1) performing vibration membrane filtration treatment on organic high-salt wastewater to remove heavy COD components in the wastewater; 2) performing vibration membrane concentration treatment on the effluent treated by vibration membrane filtration; 3) The concentrated liquid after vibrating membrane concentration treatment enters the MVR evaporation unit for evaporation and crystallization treatment, the salt produced by separation is recovered, and the water produced by separation can be directly discharged or reused. The system of the utility model can adopt different wastewater filtration and concentration modes according to the molecular weight and total distribution of COD components in wastewater, and realize the effective treatment of organic high-salt wastewater under the synergistic effect of mechanical and ultrasonic vibration forms. And can significantly improve the service life of the membrane module.

Description

A treatment and recovery system for organic high-salt wastewater

technical field

The utility model relates to a wastewater treatment technology, in particular to a treatment and recovery system for organic high-salt wastewater, which belongs to the field of environmental protection water treatment.

Background technique

High-salt wastewater widely exists in the mining and processing of chemical production and fuel gas resources. The salt content of high-salt wastewater is usually greater than 1%, and contains a variety of organic impurities, such as light organic impurities and heavy organic impurities. If it is discharged without treatment, it will cause serious pollution to the ecological environment.

At present, the most commonly used treatment methods for high-salt wastewater include: multi-stage evaporation, multi-effect flash evaporation, biochemical treatment, etc. However, due to the high salt content in high-salt wastewater, which has a strong inhibitory effect on microorganisms, it is necessary to adopt and cultivate salt-tolerant bacteria when using microbial treatment methods to treat high-salt wastewater. The cultivation process is complicated and the system stability is poor. The operating cost is high; when using evaporation processes such as MVR or multi-effect evaporation to treat high-salt wastewater, due to the presence of organic matter in the wastewater, the heavy component COD components are enriched during the evaporation process, which seriously affects the crystallization of salt, usually causing the system to run After a period of time, the evaporation crystallizer needs to be emptied and the process restarted, and a large amount of waste salt will be generated at the same time. In addition, due to the existence of volatile COD (or CODD decomposition by-products) in the steam, the heat exchange efficiency during the evaporation process is often reduced. decline.

In view of the above situation, those skilled in the art usually use organic membrane or ceramic membrane filtration technology to pretreat organic high-salt wastewater to reduce or eliminate COD components in high-salt wastewater. However, when the above-mentioned technology is used, after a period of use of the ceramic membrane filtration equipment, due to the deposition of COD components on the membrane surface, backwashing must be performed, and backwashing is not effective in improving the decline in membrane filtration efficiency due to organic matter. Not obvious; in the process of using the organic membrane, it also faces the situation of the decrease of filtration and the shortening of the membrane life caused by the deposition of COD components. In addition, traditional vibrating membrane or rotating membrane filtration is used to treat organic high-salt wastewater, which reduces the deposition on the membrane surface by increasing the shear force and flow rate on the membrane surface to improve the life of the membrane, but the traditional vibrating membrane There is a limited improvement in membrane lifetime. The long-term stable operation of the filter equipment cannot be realized.

Utility model content

The purpose of the utility model is to overcome the deficiencies of the prior art and provide a treatment and recovery system for organic high-salt wastewater with stable operation and high treatment efficiency.

In order to achieve the above object, the utility model adopts the following technical solutions:

A treatment and recovery system for organic high-salt wastewater, comprising a vibrating membrane filtration unit, a vibrating membrane concentration unit connected to the effluent of the vibrating membrane filtration unit, and an MVR connected to the effluent of the vibrating membrane concentration unit Evaporation unit.

Preferably, the vibration source of the vibrating membrane filter unit is low-frequency mechanical torsional vibration and/or high-frequency ultrasonic vibration.

Preferably, the vibration source of the vibration concentration unit is low-frequency mechanical torsional vibration and/or high-frequency ultrasonic vibration.

Preferably, the vibration frequency of the low-frequency mechanical torsional vibration is 25-66 Hz.

Preferably, the vibration frequency of the high-frequency ultrasonic vibration is 20-130 kHz.

Preferably, the filter membrane of the vibrating membrane filter unit is an ultrafiltration membrane, a nanofiltration membrane or a reverse osmosis membrane.

Preferably, the filter membrane of the vibrating membrane concentration unit is a reverse osmosis membrane.

Preferably, an electrodialysis treatment unit or an electrocoagulation treatment unit is further provided between the vibrating membrane concentration unit and the MVR evaporation unit.

Preferably, the MVR evaporation unit includes a first heat exchanger, an evaporator, a second heat exchanger, a crystallizer and a compressor connected by pipelines.

Preferably, the MVR evaporation unit includes a heat exchanger, an evaporator, a solid-liquid separator and a compressor connected by pipelines.

The beneficial effect of the utility model is that the wastewater treatment and recovery system of the utility model can adopt different wastewater filtration and concentration modes according to the molecular weight and total distribution of the COD components in the wastewater: when the COD components of the wastewater contain a molecular weight greater than When organic pollutants with a molecular weight of 150 or less than 1000 are treated, nanofiltration membranes can be selected for treatment; when the COD components of wastewater contain organic pollutants with a molecular weight above 1000, ultrafiltration membranes can be selected for treatment, and when the wastewater contains only suspended solids Or colloidal substances with large molecular weight, you can choose microfiltration membrane for treatment. Under the synergistic effect of mechanical and ultrasonic vibration forms, the deposition of COD components on the membrane surface can be effectively reduced, and the life of the membrane components can be increased by 3-5 times. In addition, under the synergistic action of the two vibration forms, it can also The filtrate flux of the membrane module is greatly improved, and finally the removal rate of COD components with a molecular weight of more than 300 can reach more than 98% before entering the evaporator of the MVR evaporation unit; High-salt wastewater produced by pharmaceutical and other industries, and the treatment effect is obvious.

Description of drawings

Fig. 1 shows the flow chart of the organic high-salt wastewater treatment and recovery system described in the utility model;

Fig. 2 shows an embodiment of the organic high-salt wastewater treatment and recovery system described in the utility model;

Fig. 3 shows another embodiment of the organic high-salt wastewater volume recovery system described in the present invention.

Detailed ways

Below in conjunction with accompanying drawing, the specific embodiment of the present utility model is described further.

As shown in Figure 1, the organic high-salt wastewater treatment and recovery system described in the utility model includes a vibrating membrane filtration unit, a vibrating membrane concentration unit and an MVR evaporation unit connected in sequence, wherein the vibrating membrane filtration unit The filter membrane can be an ultrafiltration membrane, a nanofiltration membrane or a reverse osmosis membrane. The membrane aperture of the nanofiltration membrane is preferably 0.2-1nm, and the membrane flux is 0.2-0.4t/m ² h. The membrane of the ultrafiltration membrane The pore size is preferably 0.001μm-0.02μm to remove heavy COD components in wastewater (the molecular weight of COD components is greater than 1000), such as: polycyclic aromatic hydrocarbons, polychlorinated biphenyls, etc.; concentrated water filtered by a vibrating membrane filtration unit Enter the vibrating membrane concentrating unit to concentrate the organic high-salt wastewater. The filter membrane of the vibrating membrane concentrating unit is preferably a reverse osmosis membrane, and the membrane pore size is preferably 0.1nm-1nm. The effluent concentrated by the vibrating membrane concentrating unit into the MVR evaporation unit for the separation of brine; the MVR evaporation unit includes a connected compressor, heat exchanger, evaporator and crystallizer/centrifugal separator, etc., and the MVR evaporation unit described in the utility model can be based on Depending on the object to be treated, the first-stage evaporation crystallization method or the second-stage evaporation crystallization method is adopted respectively. The crystallized salt produced by the evaporation crystallization of the MVR evaporation unit can be recovered, and the condensed water produced can be directly discharged or reused.

In the utility model, the filter membrane of the vibrating membrane filtration unit and the vibrating membrane concentrating unit can adopt a tubular module composed of multi-layer discs, and the vibration of the vibrating membrane filtering unit and the vibrating membrane concentrating unit The source can be in the form of low-frequency mechanical torsional vibration and/or high-frequency ultrasonic vibration, and the vibration frequency of low-frequency mechanical torsional vibration is 25-66Hz, and the single amplitude is 11-21mm. Single motor or double motor excitation can be used, and the sub-resonance coefficient is 0.7-0.9, within this range, the amplitude amplification factor is 1.96-5.26, and a larger amplitude can be obtained with a smaller motor power. The transverse wave transmitted in the vertical direction of the membrane surface has an attenuation wavelength of 1-2mm, which avoids the deposition and enrichment of COD components on the membrane surface; the vibration frequency of the high-frequency ultrasonic vibration is 20-130kHz, and the ultrasonic power density is 0.5-1.5w/ cm ² , ultrasonic waves form vacuum bubbles on the liquid phase and the surface of the membrane through high-frequency compression force and decompression pressure and break them up. In this process, a strong impact force will be generated to separate the COD components attached to the membrane surface from the membrane surface , In the utility model, the ultrasonic generator can be installed on both ends of the columnar membrane module or on the cylinder body, and its operating quantity can be single group or multiple groups.

Further, the treatment and recovery system described in the utility model can also include an electrodialysis or electrocoagulation unit arranged between the vibrating membrane concentrating unit and the MVR evaporation unit, and the effluent after being concentrated by the vibrating membrane concentrating unit first enters the The electrodialysis or electroflocculation unit performs electrodialysis or electroflocculation treatment to remove COD components with ultra-small molecular weight (COD component molecular weight less than 150) in the wastewater, and at the same time further concentrates the wastewater before entering the MVR evaporation unit for subsequent treatment . In addition, the treatment and recovery system described in the utility model also includes communication pipes and lift pumps arranged between the waste water treatment units.

The organic high-salt wastewater is treated by adopting the above-mentioned treatment and recovery system of the utility model, and its treatment steps include:

1) The organic high-salt wastewater containing COD components is lifted by the pump into the vibrating membrane filtration unit for vibration membrane filtration treatment to remove the heavy COD components in the wastewater;

2) The effluent of the vibrating membrane filtration unit is lifted by the pump and enters the vibrating membrane concentration unit for vibrating membrane concentration treatment. Under the action of the reverse osmosis membrane, the brine after COD is removed is pre-concentrated to a mass fraction of 8-10%. ;

3) The brine pre-concentrated by the vibrating membrane filtration unit enters the MVR evaporation unit for evaporation and crystallization treatment. Crystallized salt and condensed water are separated by evaporation and crystallized. The crystalline salt can be recovered, and the condensed water can be directly discharged or reused.

Further, the vibration source in the vibration membrane filtration treatment and vibration membrane concentration treatment steps can be in the form of low-frequency mechanical torsional vibration and/or high-frequency ultrasonic vibration, and the vibration frequency of the low-frequency mechanical torsional vibration is 25-66Hz. The amplitude is 11-21mm, and can be excited by a single motor or double motors; the vibration frequency of the high-frequency ultrasonic vibration is 20-130kHz, and the ultrasonic power density is 0.5-1.5w/cm ² .

In addition, the treatment step may also include electrodialysis treatment or electrocoagulation treatment of brine, and the brine after pre-concentration treatment by the vibrating membrane concentration unit is firstly subjected to electrodialysis treatment or electrocoagulation treatment to remove ultra-small molecular weight COD in wastewater The components then enter the MVR evaporation unit for evaporation and crystallization.

Example 1

The high-salt wastewater produced by a certain pharmaceutical company is treated with the above-mentioned treatment and recovery system and process of the utility model. The output of the wastewater is 35t/h, and the initial salt concentration is 6%. The wastewater contains a variety of organic matter, including Cellulose ethers, polycyclic aromatic hydrocarbons, lipid colloids, polychlorinated biphenyls, etc. have complex components, and the color of the wastewater is yellow and contains solid impurities.

According to the characteristics of the wastewater to be treated, the utility model adopts the treatment and recovery process as shown in Figure 2, wherein: the filter membrane of the vibrating membrane filtration unit adopts a nanofiltration membrane with a membrane aperture of 1 nm, and its membrane flux is 0.2-0.4 t/m ² h, the vibration source adopts low-frequency mechanical torsional vibration with a vibration frequency of 58Hz and high-frequency ultrasonic vibration with a vibration frequency of 88kHz at the same time, which can remove all solid impurities in wastewater and terminate COD components; due to the light The COD component is negligible. After filtration, the COD content in the liquid is 350mg/l, and the COD component is a small amount of hydrocarbon substances with a molecular weight less than 200. Therefore, in this embodiment, the wastewater treated by nanofiltration directly enters the vibrating membrane concentrating unit for concentrating treatment. The concentrating membrane of the vibrating membrane concentrating unit can adopt a reverse osmosis membrane with a membrane pore size of 0.2nm to convert the waste water After the concentration is concentrated to 8-10%, the wastewater enters the MVR evaporation unit for evaporation and crystallization treatment. In this embodiment, the MVR evaporation unit adopts a two-stage evaporation crystallization mode, including a first heat exchanger, an evaporator, a second heat exchanger, a crystallizer and a compressor, and the concentrated liquid of the vibrating membrane concentration unit passes through the second After exchanging heat in the first heat exchanger, it enters the evaporator for evaporation. At this time, the concentration of the wastewater becomes about 28%. Then, the nearly saturated concentrated liquid from the evaporator passes through the second heat exchanger again and enters the crystallization process. crystallization separation, the separated crystalline salt can be recovered, and the separated secondary steam enters the first heat exchanger after being compressed by the compressor for circulating water replenishment, etc., wherein: the pressure of the compressor is 10kPa-40kPa, the compressor The form can be a centrifugal compressor, a Roots compressor or a combination thereof, and the heat exchange form of the first and second heat exchangers can be external heat exchange of a tank, rising film evaporative heat exchange or falling film evaporative heat exchange. hot etc. Using the above-mentioned evaporation and crystallization process, during the entire operation process, only about 50 degrees of electricity is needed for evaporating a ton of water, which is energy-saving and environmentally friendly.

Example 2

The high-salt wastewater produced in the production process of a chemical plant is treated with the treatment and recovery system and process described in the present invention. The salt content in the wastewater is about 600mg/L, and the wastewater output is 10t/h. The content of COD in the product is 1500mg/l, but the molecular weight of the COD component is small, and the main components of COD are benzene series, alkanes, organic phosphorus and so on.

According to the characteristics of the above-mentioned waste water, this embodiment adopts the treatment and recovery process as shown in Figure 3, wherein: the filter membranes of the vibrating membrane filtration unit and the vibrating membrane concentration unit all adopt reverse osmosis membranes, or as shown in Figure 3 process, vibrating The membrane filtration unit and the vibration membrane concentration unit can be integrated into the same RO membrane filtration concentration unit. The wastewater is concentrated by RO membrane filtration to remove most of the COD components in the wastewater, and the wastewater is concentrated at the same time; the wastewater is concentrated by RO membrane filtration Finally, the wastewater enters the electrodialysis unit for electrodialysis treatment to remove 70-90% of small molecular weight COD components in the wastewater, and can further concentrate the wastewater. The COD content of the treated liquid is about 150mg/l, and the COD group Divided into small molecular weight alkanes; then, the waste water enters the MVR evaporation unit. In this embodiment, due to the small amount of evaporation, the MVR evaporation unit adopts a primary evaporation crystallization mode, including a compressor, a heat exchanger, an evaporation The concentrated liquid produced by the electrodialysis unit enters the evaporator for heat exchange and evaporation after heat exchange by the heat exchanger, and then the feed liquid produced by the evaporation of the evaporator enters the centrifugal separator for solid-liquid salt-water separation. Separation, the separated salt can be recovered, and the separated liquid can be mixed with the concentrated liquid produced by the electrodialysis unit and then enter the MVR evaporation unit for the next cycle treatment. The secondary vapor generated by the evaporator is compressed by the compressor and enters the heat exchange to cycle again.

The wastewater treatment and recovery system and process of the utility model can adopt different wastewater filtration and concentration modes according to the molecular weight and total distribution of COD components in the wastewater, and finally can realize the COD components with a molecular weight of more than 300 before entering the MVR evaporation unit. Before the evaporator, its removal rate can reach more than 98%, and the service life of the membrane module of the same material can be increased by 3-5 times, and the continuous operation time of the MVR evaporation unit can be extended by 4-6 times. In addition, the utility model can adopt the action of high-frequency ultrasonic vibration and mechanical vibration system. Under the action of ultrasonic waves, the COD deposition components peeled off from the membrane surface are further pushed away from the membrane surface by the shear wave generated by low-frequency torsional oscillation. The life of the membrane under the synergistic effect is longer than In the case of using ultrasonic waves and low-frequency mechanical torsion alone, and under the same osmotic pressure and permeable materials, when the double vibrations act synergistically, the permeation flux of the membrane is greater than the increase in membrane flux when using a single vibration form , improve the efficiency of wastewater treatment.

In summary, the above are only preferred embodiments of the present utility model, and are not intended to limit the implementation scope of the present utility model. That is, all equivalent changes and modifications made according to the content of the patent scope of the utility model shall belong to the technical category of the utility model.

Claims (10)

1. A treatment and recovery system for organic high-salt wastewater, characterized in that: comprising a vibrating membrane filtration unit, a vibrating membrane concentrating unit connected to the outlet water of said vibrating membrane filtering unit, and a vibrating membrane concentrating unit connected with said vibrating membrane filtration unit The effluent of the unit is connected to the MVR evaporation unit. 2. The treatment and recovery system according to claim 1, characterized in that: the vibration source of the vibrating membrane filter unit is low-frequency mechanical torsional vibration and/or high-frequency ultrasonic vibration. 3. The treatment and recovery system according to claim 1, characterized in that: the vibration source of the vibration concentration unit is low-frequency mechanical torsional vibration and/or high-frequency ultrasonic vibration. 4. The treatment and recovery system according to claim 2 or 3, characterized in that: the vibration frequency of the low-frequency mechanical torsional vibration is 25-66 Hz. 5. The treatment and recovery system according to claim 2 or 3, characterized in that: the vibration frequency of the high-frequency ultrasonic vibration is 20-130 kHz. 6. The treatment and recovery system according to claim 1, characterized in that: the filter membrane of the vibrating membrane filter unit is an ultrafiltration membrane, a nanofiltration membrane or a reverse osmosis membrane. 7. The treatment and recovery system according to claim 1, characterized in that: the filter membrane of the vibrating membrane concentration unit is a reverse osmosis membrane. 8. The treatment and recovery system according to claim 1 or 2 or 3 or 6 or 7, characterized in that: an electrodialysis treatment unit or an electrocoagulation treatment unit is also arranged between the vibrating membrane concentration unit and the MVR evaporation unit . 9. The treatment and recovery system according to claim 1 or 2 or 3 or 6 or 7, characterized in that: the MVR evaporation unit comprises a first heat exchanger, an evaporator, a second heat exchanger connected by pipelines, crystallizer and compressor. 10. The treatment and recovery system according to claim 1 or 2 or 3 or 6 or 7, characterized in that: the MVR evaporation unit includes a heat exchanger, an evaporator, a solid-liquid separator and a compressor connected by pipelines.