阅读说明：本技术 一种废水处理方法和装置及系统 (Wastewater treatment method, device and system ) 是由 张泽远 方晓萍 于 2019-09-23 设计创作，主要内容包括：本发明属于废水处理技术领域,具体涉及一种废水处理方法和装置及系统。本发明提供的废水处理方法包括将待处理的废水进行电化学处理,其中所用的阳极材料为贵金属或钛,阴极材料为碳。本发明采用上述阳极材料和阴极材料对废水进行电化学处理,可以更有效地降解废水中的有机污染物,从而能够达到安全排放的要求,因此通常不必配合生化法等后处理方法。本发明方法处理成本低,易于产业化,有明显的环境、社会及经济效益。(The invention belongs to the technical field of wastewater treatment, and particularly relates to a wastewater treatment method, a device and a system. The wastewater treatment method provided by the invention comprises the step of carrying out electrochemical treatment on wastewater to be treated, wherein the used anode material is noble metal or titanium, and the cathode material is carbon. The invention adopts the anode material and the cathode material to carry out electrochemical treatment on the wastewater, can more effectively degrade organic pollutants in the wastewater, thereby meeting the requirement of safe discharge, and generally needing no post-treatment methods such as a biochemical method and the like. The method has low treatment cost, is easy to industrialize, and has obvious environmental, social and economic benefits.)

1. A wastewater treatment method is characterized by comprising the step of carrying out electrochemical treatment on wastewater to be treated, wherein the anode is made of noble metal or titanium, and the cathode is made of carbon.

2. The wastewater treatment method according to claim 1, wherein the noble metal is selected from one or more alloys of gold, silver, platinum, palladium, osmium, iridium, ruthenium and rhodium, preferably iridium or ruthenium; and/or the presence of a gas in the gas,

the cathode is made of one or more materials selected from carbon, graphite, graphene, carbon fiber and diamond after conductive modification or doping; or the cathode is made of carbon or carbon-based material mixture.

3. The method for treating wastewater according to claim 1 or 2, wherein the surface of the cathode is smooth, or the cathode has a multi-layer loose lamellar structure, a porous structure or a structure with rough surface.

4. The method for treating waste water according to any one of claims 1 to 3, wherein a direct current voltage, an alternating current voltage, a variable duty ratio voltage or a waveform pulse voltage is applied between the cathode and the anode during the electrochemical treatment;

preferably, during the electrochemical treatment: the current intensity range for treating 1 cubic meter of wastewater is as follows: 0.1 to 10000 amps, voltage range: 0.1 to 380 volts; alternatively, the current intensity is 150-200A for each 1 cubic meter of wastewater, and the voltage is 30-40V.

5. The method for treating wastewater according to any one of claims 1 to 4, wherein a batch electrochemical treatment mode, specifically an electrochemical treatment mode, is adopted for a period of time, the electrochemical treatment is stopped and kept for a period of time, and the treatment is repeatedly circulated until the wastewater is treated to the required requirement;

preferably, the batch electrochemical treatment mode is as follows: performing electrochemical treatment for 10-100min, stopping the electrochemical treatment for 0.2-20min, and repeating the cycle treatment until the wastewater is treated to the required requirement;

further preferably, when the intermittent electrochemical treatment mode is adopted, a step of performing treatment after the anode and the cathode are reversely connected with the anode and the cathode of the power supply is added in the processes of the electrochemical treatment and stopping the electrochemical treatment; more preferably, the treatment time for each of said rejections is 0.5-20 min.

6. A method for treating waste water according to any one of claims 1 to 5, wherein the waste water to be treated is in a substantially static or substantially steady-flow state; alternatively, the treated wastewater is in a turbulent flow state or in a steady flow and turbulent flow alternating state.

7. The method for treating wastewater according to any one of claims 1 to 6, wherein the wastewater contains one or more of dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, polyvinylpyrrolidone, polyethylene glycol, and dimethylsulfoxide;

or the waste water to be treated contains 0.01 to 1 percent of dimethyl formamide, 0.1 to 8 percent of dimethyl acetamide, 0.01 to 5 percent of N-methyl-2-pyrrolidone, 0.1 to 3 percent of polyvinylpyrrolidone, 0.1 to 20 percent of polyethylene glycol and 5000-200000mg/L of COD.

8. An electrochemical wastewater treatment apparatus comprising an anode and a cathode, wherein the anode and the cathode are made of the same material as in claim 1 or 2;

preferably, the surface of the cathode is smooth, or the cathode is a multi-layer loose lamellar structure, a porous structure or a structure with rough surface.

9. The electrochemical wastewater treatment apparatus according to claim 8, further comprising a water flow control stirring device or a water pusher for causing a turbulent flow of water between the cathode and the anode; and/or the presence of a gas in the gas,

the electrochemical wastewater treatment device also comprises a power supply which can provide direct current voltage, alternating current voltage or variable duty ratio voltage or waveform pulse voltage; and/or the presence of a gas in the gas,

the electrochemical wastewater treatment device also comprises a sludge scraper collector which is used for collecting the sludge floating upwards after electrochemical treatment.

10. An electrochemical wastewater treatment system, comprising:

an electrochemical wastewater treatment apparatus according to claim 8 or 9;

the electrochemical treatment pool is provided with the electrochemical wastewater treatment device and is used for carrying out electrochemical treatment on wastewater;

a wastewater adjusting tank for temporarily storing wastewater to be treated;

a first pump;

a first conduit; conveying the wastewater to be treated from the wastewater regulating tank to the electrochemical treatment tank through the first pump and the first pipeline;

a second pump;

a second conduit;

a sludge sedimentation tank; conveying the sludge generated in the electrochemical treatment process in the electrochemical treatment tank to the sludge sedimentation tank through the second pump and the second pipeline;

a third pump;

a third pipeline; the supernatant in the sludge sedimentation tank is conveyed to the wastewater adjusting tank through the third pump and the third pipeline;

the clean water tank is used for storing the clean water after the electrochemical treatment;

the fourth pipeline is used for conveying the clean water treated in the electrochemical treatment tank to the clean water tank;

and the sludge discharge pipe is used for discharging the floating sludge in the electrochemical treatment tank.

Technical Field

The invention belongs to the technical field of wastewater treatment, and particularly relates to treatment of wastewater containing dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, polyvinylpyrrolidone and polyethylene glycol. The invention also relates to a device and a system for treating the wastewater.

Background

Dimethylformamide (DMF), Dimethylacetamide (DMAC), N-methyl-2-pyrrolidone, polyvinylpyrrolidone, polyethylene glycol or dimethyl sulfoxide are used as organic solvents with excellent performance and main fine chemical raw materials, and are widely applied to ultrafiltration microfiltration membrane production, dye, synthetic leather industry and the like. DMF has biotoxicity, inhibits microbial activity after being discharged into water, and seriously pollutes water; DMF enters the body via the respiratory tract, digestive tract and skin and also has some toxicity. Therefore, it is necessary to treat wastewater containing DMF, DMAC or the like. Separation of these components is difficult due to the azeotropic boiling point of some of the materials in the wastewater with water. At present, the domestic and foreign methods for treating waste water such as DMF, DMAC, polyvinylpyrrolidone and the like include a reduced pressure distillation method, an extraction adsorption method, a biochemical method, a photocatalytic oxidation method, a chemical method (an alkalization method) and the like. Generally, these methods cannot completely oxidize and degrade organic pollutants in water, and only can be used as a pretreatment method, but not as a final treatment method. Meanwhile, the methods have high treatment cost and are difficult to popularize and apply.

In addition, although some methods for electrochemically treating water treatment wastewater are reported in the prior art, the methods cannot completely degrade organic pollutants in water to meet the requirement of safe discharge, and therefore, the methods also need to be matched with treatment methods such as biochemical methods.

Disclosure of Invention

In view of the above, the present invention provides a wastewater treatment method, which comprises subjecting wastewater to be treated to electrochemical treatment, wherein the anode material used in the electrochemical treatment is noble metal or titanium (Ti), and the cathode material used in the electrochemical treatment is carbon.

The inventor of the invention finds in a great deal of practice that the anode and the cathode of the electrode respectively adopt the materials to carry out electrochemical treatment on the wastewater, so that organic pollutants in the wastewater can be more effectively degraded, and the requirement of safe discharge can be met, therefore, the post-treatment methods such as a biochemical method and the like do not need to be matched.

In some embodiments of the present invention, the noble metal is selected from gold (Au), silver (Ag), platinum (Pt), palladium (Pd), osmium (Os), iridium (Ir), ruthenium (Ru), rhodium (Rh), or an alloy thereof.

In some embodiments of the invention, iridium or ruthenium is selected as the anode material.

The invention selects the noble metal or titanium as the anode material and has the outstanding advantages of strong oxidation resistance, slow passivation speed and improvement of the efficiency of electrochemical wastewater treatment in the process of electrochemical wastewater treatment.

Carbon in the present invention generally refers to a substance containing carbon element.

In some embodiments of the present invention, the cathode is made of one or more materials selected from carbon, graphite, graphene, carbon fiber, and diamond after conductive modification or doping; or the cathode is made of carbon or carbon-based material mixture.

In some embodiments of the invention, graphite is selected as the cathode material.

In some embodiments of the invention, the surface of the cathode is smooth.

In some preferred embodiments of the present invention, the cathode is a multi-layer loose sheet structure, a porous structure or a structure with a rough surface (non-planar design), which not only increases the electrode area, but also enables the attachment on the cathode to be deposited asymmetrically, thereby facilitating the self-cleaning and manual intervention of the pollutants.

The present inventors have surprisingly found that the use of the above-mentioned carbon as a cathode and the use of the above-mentioned noble metal or titanium as an anode in the electrochemical treatment of wastewater can improve the electrode activity, improve the electrochemical treatment efficiency, and reduce the treatment cost. Particularly, the anode and the cathode are selected to remarkably slow down the passivation speed of the electrode and keep the continuity and stability of electrochemical treatment. Meanwhile, the electrode material is selected to facilitate cleaning and maintenance of the electrode.

Generally, when the electrochemical treatment is carried out, a direct current voltage, an alternating current voltage, or a variable duty ratio voltage or a waveform pulse electric voltage can be loaded between the cathode and the anode so as to realize the electrochemical treatment of the wastewater. The preferred mode is to adopt a direct current switch constant current power supply to supply power, so that the input power is stable, and the wastewater treatment efficiency is improved.

In order to further improve the treatment efficiency of organic pollutants in wastewater, some embodiments of the present invention further optimize the current intensity and voltage used in the electrochemical treatment process, specifically as follows: the current intensity range for treating 1 cubic meter of wastewater is as follows: 0.1 to 10000 amperes (a), voltage range: 0.1 volts (V) to 380 volts (V). In some embodiments of the invention, the current is 150-200 amps (e.g., 150, 160, 190, or 200 amps) per 1 cubic meter of wastewater being treated and the voltage is 30-40 volts (e.g., 30, 36, or 40 volts).

In some embodiments of the invention, the wastewater treatment time is from 0.1 hour to 240 hours. For water quality which is difficult to treat, the treatment time can be properly prolonged.

In some embodiments of the present invention, the wastewater refers to wastewater (or sewage) containing one or more of Dimethylformamide (DMF), Dimethylacetamide (DMAC), N-methyl-2-pyrrolidone, polyvinylpyrrolidone, polyethylene glycol, and dimethyl sulfoxide, and specifically includes, for example, wastewater from ultrafiltration and microfiltration membrane production, wastewater from artificial leather and leather processing, and wastewater from printing and dyeing, etc.

The experimental results show that the treatment method in some embodiments of the invention has better treatment effect especially on waste water containing one or more of Dimethylformamide (DMF), Dimethylacetamide (DMAC) and N-methyl-2-pyrrolidone.

According to the method, the Chemical Oxygen Demand (COD) of the treated water can be efficiently reduced due to the oxidation and reduction effects on the organic pollutants in the electrochemical treatment process.

According to the method of the present invention, in some embodiments, the oxide or reduced matter of the pollutant or its compound may be aggregated, or floated, or precipitated due to oxidation or reduction of the pollutant during the electrochemical treatment process, and the Chemical Oxygen Demand (COD) of the treated wastewater may be further reduced by separating the aggregated matter.

It has been found experimentally that during the electrochemical treatment according to some embodiments of the present invention, the oxides or the reducers of the contaminants or the compounds thereof are inevitably attached to the electrode (mainly the cathode) after being accumulated, thereby causing passivation of the electrode and affecting the electrochemical treatment efficiency. The present inventors have continued intensive studies with respect to this problem. As a result, it has been found that in the electrochemical treatment process according to some embodiments of the present invention, the adhesion of the contaminants to the electrode can be effectively reduced and the passivation of the electrode can be delayed by using the intermittent electrochemical treatment.

The intermittent electrochemical treatment method is to perform electrochemical treatment (power on) for a certain period of time under the substantially same conditions, then stop the electrochemical treatment (for example, power off) for a certain period of time, (and perform electrochemical treatment under the substantially same conditions), and thus repeat the cyclic treatment until the wastewater is treated to a desired requirement or target value (for example, COD is used as an index). In some embodiments of the present invention, the batch electrochemical treatment mode is: electrochemical treatment is carried out for 10-100min under the basically same conditions, the electrochemical treatment is stopped for 0.2-20min, and the cyclic treatment is repeated until the wastewater is treated to the required requirement or target value.

The present invention also finds that, in the electrochemical treatment process according to some embodiments of the present invention, when the above-mentioned intermittent electrochemical treatment mode is adopted, a step of performing treatment after the anode and the cathode are reversely connected to the positive and negative electrodes of the power supply is added in the electrochemical treatment (power-on) and the electrochemical treatment (power-off) is stopped, that is, the positive electrode of the power supply is switched to be connected to the cathode, and the negative electrode of the power supply is switched to be connected to the anode, so that the adhesion of the contaminants on the electrodes can be more effectively removed under the driving of the reverse current, thereby further delaying the passivation of the electrodes. In the electrochemical treatment process according to some embodiments of the present invention, the treatment time per the reverse connection is 0.5 to 20 min.

In some embodiments of the electrochemical treatment process of the present invention, the wastewater being treated is in a substantially static or substantially steady flow state.

The invention further researches and discovers that the adhesion amount of pollutants (including particle pollutant sediment or floating matters accumulated in the electrochemical treatment process) on an electrode (especially a cathode) can be effectively reduced if the treated wastewater is in a turbulent flow state, the passivation of the electrode is delayed, and the wastewater in the turbulent flow state is more beneficial to improving the oxidation efficiency of organic pollutants.

In some embodiments of the invention, the wastewater to be treated is in a turbulent flow regime or alternating steady flow and turbulent flow regime.

The wastewater to be treated can be made to be in a turbulent state by means of the techniques known in the art, and the present invention is not particularly limited.

In some embodiments of the invention, the wastewater to be treated has a Dimethylformamide (DMF) content of 0.01-1%, a Dimethylacetamide (DMAC) content of 0.1-8%, an N-methyl-2-pyrrolidone content of 0.01-5%, a polyvinylpyrrolidone content of 0.1-3%, a polyethylene glycol content of 0.1-20%, and a COD of 5000-. The method of the invention can achieve excellent treatment effect on the wastewater.

On the basis of the common knowledge in the field, the above-mentioned preferred conditions can be combined with each other to obtain preferred embodiments of the present invention.

Based on the above research, the present invention also provides an electrochemical wastewater treatment device, comprising an anode and a cathode, wherein the anode and the cathode are made of the same materials as above.

In some embodiments of the invention, the cathode of the wastewater treatment plant is of a smooth-surfaced structure. In some preferred embodiments of the present invention, the cathode of the wastewater treatment device is a multi-layer loose lamellar structure, a porous structure or a structure with a rough surface (non-planar design), so that the electrode area is increased, and attachments on the cathode are deposited asymmetrically, thereby facilitating self-cleaning and manual intervention and shedding of pollutants.

In some embodiments of the present invention, the wastewater treatment device further comprises a water flow control stirring device or a water pusher for making the water flow between the cathode and the anode turbulent.

It is understood that the electrochemical wastewater treatment apparatus of the present invention further comprises a power source, which in some embodiments of the present invention can provide a dc voltage, an ac voltage, or a variable duty cycle voltage or a waveform pulse voltage to achieve electrochemical treatment of wastewater. In some preferred embodiments of the invention the power supply is a dc constant current power supply or a dc constant voltage power supply.

In some embodiments of the present invention, the electrochemical wastewater treatment apparatus further comprises a sludge scraper collector for collecting sludge floating upward after electrochemical treatment.

In some embodiments of the invention, the anode and the cathode are parallel plate electrodes, columnar electrodes or tubular electrodes.

Advantageous effects

The electrochemical treatment method used in the embodiment of the invention can thoroughly oxidize, decompose or separate pollutants in water. For wastewater (or sewage) with COD of 5000-. The method provided by the embodiment of the invention has the advantages of low treatment cost, easiness in industrialization and obvious environmental, social and economic benefits.

Drawings

FIG. 1 is a schematic flow diagram of a wastewater treatment process according to an embodiment of the present invention;

FIG. 2 shows a wastewater treatment process and apparatus and system used in accordance with one embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In some embodiments of the present invention, the wastewater treatment process is as shown in fig. 1 and 2, and the wastewater treatment process is as follows: the wastewater to be treated can be temporarily placed in a wastewater adjusting tank for storage; the wastewater to be treated in the wastewater adjusting tank is lifted by a pump to enter an electrochemical treatment tank; under the electrochemical treatment action of a cathode and an anode of an electrode in the electrochemical treatment tank, dirt in the wastewater is oxidized and reduced, and simultaneously, sludge sediment and/or floating matters can be generated by the aggregated particle pollutants, wherein the sludge sediment and/or the aggregated floating matters are respectively discharged into the sludge sedimentation tank through pipelines, supernatant liquid in the sludge sedimentation tank after sedimentation is pumped back to the wastewater regulation tank, and the sludge in the sludge sedimentation tank is periodically discharged and then is subjected to dehydration and harmless treatment; after the treated wastewater in the electrochemical treatment tank is subjected to electrochemical treatment for a period of time, aggregate precipitation and floating matter removal, COD of the treated wastewater is reduced to a treatment target value, and the treated wastewater is discharged into a clean water tank through a pipeline arranged in the electrochemical treatment tank so as to be discharged or recycled.

In some embodiments of the present invention, an electrochemical wastewater treatment apparatus is provided as shown in FIG. 2 (arrows indicate water flow direction). Specifically, the electrochemical wastewater treatment apparatus comprises electrodes including a cathode 7 (in this embodiment, a parallel plate electrode) and an anode 8 (in this embodiment, a parallel plate electrode), and the materials used for the cathode 7 and the anode 8 are the same as those described above. At least one of the cathode 7 and the anode 8 is provided.

Wherein in some embodiments, the anode material is ruthenium and the cathode material is graphite; in some embodiments, the anode is ruthenium and the cathode is porous graphite with a loose lamellar structure; in some embodiments, the material of the anode is iridium and the material of the cathode is graphite.

Further, in some embodiments, the cathode is porous or rough-surfaced (non-planar design), which both increases the electrode area and provides for asymmetric deposition of attachments on the cathode, thereby facilitating self-cleaning and manual intervention of contaminants.

Further, in some embodiments, the electrochemical wastewater treatment apparatus further comprises a water flow control stirring device 9 or a water pusher 9 for causing the water flow between the cathode and the anode to form a turbulent flow.

Further, in some embodiments, the electrochemical wastewater treatment apparatus further comprises a power supply 27 that can provide a direct current voltage, an alternating current voltage, or a variable duty cycle voltage or a waveform pulse voltage to achieve electrochemical treatment of wastewater.

Further, in some embodiments, the electrochemical wastewater treatment apparatus further comprises a sludge scraper collector 24 for collecting sludge floating upward after the electrochemical treatment. The sludge scraper 24 may be provided in a manner known in the art so long as it facilitates collection of the sludge that floats after electrochemical treatment.

In one embodiment of the present invention, an electrochemical wastewater treatment system is also provided, as shown in FIG. 2. Specifically, the electrochemical wastewater treatment system comprises the electrochemical wastewater treatment device, which is disposed in an electrochemical treatment tank 5, and electrochemically treats wastewater in the electrochemical treatment tank 5.

Further, the system also comprises a wastewater adjusting tank 1 for temporarily storing wastewater 2 to be treated; a first pump 3; a first duct 4; the wastewater 2 to be treated is conveyed from the wastewater adjusting tank 1 to the electrochemical treatment tank 5 through the first pump 3 and the first pipeline 4; electrochemically treating the wastewater 6 in the electrochemical treatment cell 5; the sludge precipitate 10 generated during the electrochemical treatment process will normally settle naturally to the bottom of the electrochemical treatment tank 5.

Further, the system also comprises a second pump 11; a second pipe 12; a sludge settling tank 13; the sludge 10 generated in the electrochemical treatment process in the electrochemical treatment tank 5 is conveyed to the second pump 11 and the second pipeline 12

A sludge settling tank 13; the bottom of the sludge sedimentation tank 13 is settled sludge 14, and the upper part is sludge tank supernatant 15.

Further, the system also includes a third pump 16; a third duct 17; the supernatant 15 in the sludge settling tank 13 is transferred to the wastewater adjusting tank 1 through the third pump 16 and the third pipe 17.

Further, the system comprises a clean water reservoir 18 for storing electrochemically treated clean water 19; the clean water tank 18 is provided with a discharge port 20 for discharging the treated clean water; a fourth pipeline 21 for transporting the clean water treated in the electrochemical treatment tank 5 to the clean water tank 18; a control valve 22 for controlling opening and closing of the fourth pipe 21; a sludge discharge pipe 23 for discharging the floating sludge from the electrochemical treatment tank 5, for example, to the sludge settling tank 13.

Further, the system further includes an anode connection wire 25; a cathode connection wire 26; a power supply 27. During the electric treatment, the anode 8 is connected to the positive pole of a power supply 27 via an anode connecting wire 25, and the cathode 7 is connected to the negative pole of the power supply 27 via a cathode connecting wire 26.

The following waste water was taken from a plant, and the waste water contained 0.1% of Dimethylformamide (DMF), 1% of Dimethylacetamide (DMAC), 0.1% of N-methyl-2-pyrrolidone, 0.1% of polyvinylpyrrolidone, 1% of polyethylene glycol, and 52000mg/L of COD.

The COD of the present invention can be detected by methods conventional in the art. In the following examples and comparative examples, measurement was carried out using a LC4-CNP type multiparameter water quality analyzer (produced by Hangzhou continental engineering instruments Co., Ltd.), and the COD measurement principle (chromium method) thereof was as follows: in the presence of strong acid solution and excessive potassium dichromate, silver sulfate is used as a catalyst, reducing substances in water are heated and catalytically oxidized, and the COD value of a water sample is determined according to the relationship between the absorbance value of hexavalent chromium or trivalent chromium and the COD value of the water sample.