CN111204852B - Livestock and poultry wastewater tail water treatment system - Google Patents

Abstract

The invention provides a livestock and poultry wastewater tail water treatment system, which comprises a reactor for treating livestock and poultry wastewater tail water, wherein a reaction chamber of the reactor is divided into a cathode reaction chamber and an anode reaction chamber through a cation exchange membrane, and graphene aerogel is respectively used as a cathode and an anode of the cathode reaction chamber and the anode reaction chamber; when the livestock and poultry wastewater tail water is treated, firstly, the livestock and poultry wastewater tail water reacts in an anode reaction chamber to remove antibiotics and part of copper ions, and certain electrolyte is added in a cathode reaction chamber to ensure that the anode reaction chamber normally reacts; then the tail water treated by the anode reaction chamber is put into the cathode reaction chamber again to remove copper ions and part of residual antibiotics, and meanwhile, the anode reaction chamber continues to treat a new round of livestock and poultry wastewater tail water. The system has high treatment efficiency and low energy consumption.

Description

A livestock and poultry waste water tail water treatment system

technical field

The invention relates to the technical field of sewage, in particular to a method for treating tail water of livestock and poultry waste water.

Background technique

In the development of the livestock and poultry industry, antibiotics and heavy metal ions are often used as feed additives to be added to the feed, and the added amount far exceeds the absorption of livestock and poultry, so most of the antibiotics and heavy metals are discharged in the form of livestock and poultry manure and livestock and poultry wastewater. Antibiotics and heavy metals are not easy to be removed in the environment, and antibiotics will form complexes with heavy metal ions, which will increase the difficulty of removal and accumulate in the environment, thereby causing serious environmental pollution. Residual antibiotics and heavy metals in the environment have caused are of great concern because of their potential long-term adverse threats to human health and natural ecosystems.

So far, the methods of treating antibiotics and heavy metal complexes in livestock and poultry wastewater mainly include physical treatment, biological treatment and advanced oxidation. In the physical treatment method, there are mainly problems such as the need for strong adsorbent characteristics, a large amount of adsorbent, and a long contact time with pollutants. Moreover, this method simply transfers the pollutants from the liquid phase to the solid phase. In the real sense of removal, the subsequent treatment of the deactivated adsorbent is also more troublesome, so this method is not suitable for the removal of complex pollutants. When the biological treatment method is used to remove the complex pollutants, the disadvantage is that the treatment period is long, the toxicity of the antibiotics after treatment is uncertain, and it is easy for the microbial cells to have an antibacterial effect on the antibiotics, so that the pollutants escape treatment and remain in the water body. Therefore, the biological method is not an ideal method for the treatment of complex pollutants.

In recent years, Advanced Electrocatalytic Oxidation Process (AEOP) is one of the most widely concerned wastewater treatment technologies. Electrolysis is the process of passing electric current through an electrolyte solution to induce redox reactions on the cathode and anode. Existing research shows that electrochemical method has great potential in the treatment of livestock and poultry wastewater. The research takes electrochemical method as the technical core and adopts multipolar packed bed (granular activated carbon is filled between electrode plates as particle electrode, without diaphragm). The electrolytic cell body is a plexiglass tank, the electrode plates are made of cathode and anode homogeneous aluminum plate electrodes, the particle electrodes are activated carbon, and the reaction device is shown in Figure 1, which includes a DC voltage stabilized power supply 1, an anode plate 2, particle electrodes 3, Cathode plate 4, valve 5, water outlet 6. During the reaction, the antibiotics will be oxidized and removed near the anode plate through direct electrochemical oxidation and indirect electrochemical oxidation. During the reaction process, the antibiotics will be oxidized and then removed by direct electrochemical oxidation and indirect electrochemical oxidation in the vicinity of the anode plate, the principle of which is shown in Figure 2. The heavy metal ions will undergo a reduction reaction near the cathode plate and then be removed. The principle is as follows:

M ^Z+ +Ze ^- →M ⁰ (M=Cu, Zn, Pb, etc.)

Although the electrochemical advanced oxidation technology has good results in the treatment of livestock and poultry wastewater, there are still some problems. First, the electrode is easily passivated, which will cause the reaction rate in the system to decrease in the later stage; secondly, with the progress of the electrochemical oxidation reaction , the organic pollutants in the system gradually decrease, which will affect the mass transfer rate in the system and lead to the decrease of the reaction rate in the later stage. Especially in the treatment of livestock and poultry wastewater tail water, the traditional electrochemical oxidation method is greatly limited. However, in the current situation of livestock and poultry wastewater discharge, even if the wastewater discharge standards are met, the wastewater still contains some antibiotics and heavy metal ions. The most typical feature of them is the low concentration, which leads to the limitation of mass transfer rate of the system during post-treatment. In view of the potential harm of antibiotics and heavy metal ions to the environment, advanced treatment of livestock and poultry wastewater tail water is imperative. , If the traditional electrochemical oxidation method is used to treat tail water, it will cause problems such as low current efficiency and insufficient energy utilization (when advanced oxidation is used to treat tail water, it will be limited by the mass transfer resistance of low-concentration pollutants in the tail water, so Affect current efficiency and treatment effect), and the traditional electrochemical oxidation method to remove pollutants is only redox reaction, and the efficiency is relatively low. Therefore, we must improve on the original basis.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the above-mentioned defects in the prior art, and to provide a method for treating tail water of livestock and poultry wastewater, which utilizes the adsorption properties of electrodes and the particularity of the reaction device (dual-chamber reactor), and the adsorption effect of electrodes Contaminants can be enriched, thereby reducing the impact of mass transfer; and the dual-chamber reactor can improve the efficiency of the reaction.

Beneficial effects:

First, in the prior art, whether it is a physical treatment method, a biological treatment method or an advanced oxidation method, they are all treated before the wastewater is discharged, and no advanced treatment of the tail water is performed. The present invention is mainly for advanced treatment of tail water discharged from livestock and poultry wastewater, so that the purpose of zero discharge or close to zero discharge of antibiotics and heavy metal ions in livestock and poultry wastewater is achieved. Through exploration, it is concluded that the present invention has a better removal effect on the complex solution of antibiotics and heavy metals, and antibiotics and heavy metals can be completely removed in a low concentration range (10ppm, 20ppm); in a high concentration range (50ppm), heavy metals It can be completely removed, and the antibiotic removal rate is as high as 82%.

Second, the present invention adopts a double-chamber reactor, and compared with a single-chamber reactor, the present invention has higher treatment efficiency per unit time.

Thirdly, the electrode preparation method used in this experiment is simple and the reaction conditions are mild, but the electrolysis effect is good without passivation.

Fourth, the present invention diversifies the removal methods of pollutants in the same time unit, thereby increasing the reaction rate.

Fifth, the electrochemical oxidation process of the present invention is simple and clear, but has better treatment efficiency than the traditional electrochemical oxidation process.

Sixth, when the present invention treats the tail water of actual livestock and poultry wastewater, the removal rate of TOC can reach 63%, and the removal rate of copper ions can reach 88%.

Description of drawings

Fig. 1 is the structure diagram of electrochemical method device in the prior art;

Fig. 2 is the schematic diagram of prior art electrochemical reaction; Wherein (a) is the schematic diagram of direct electrochemical oxidation; (b) is the schematic diagram of indirect electrochemical oxidation;

Fig. 3 is the principle diagram of reaction device of the present invention;

Figure 4 is a graph showing the degradation of tetracycline and copper ion complexes with different concentrations of the present invention in the experiment.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention are described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Fig. 3 is the principle diagram of the reaction device of the present invention, as shown in Fig. 3, the system provided by the present invention, for the treatment of livestock and poultry waste water tail water, the present invention adopts a double-chamber reactor (the cathode chamber and the anode chamber are separated by a cation exchange membrane The anode and cathode of the electrochemical reaction are isolated, making them separate anode and cathode chambers), and graphene aerogels are used as cathode and anode to treat pollutants.

Next, the complexes of antibiotics and copper ions are used as simulated pollutants for removal (as shown in Figure 3). In the anode chamber, there are three removal paths for antibiotics, the first is to be directly adsorbed by the electrode, the second is to be removed by direct electrochemical oxidation, and the third is to be removed by indirect oxidation reaction; and in the first step The direct adsorption of pollutants by the electrode of the tungsten electrode will not affect the pollutant removal efficiency, the reason is that ① the adsorption of the graphene aerogel electrode is very good, and ② the present invention is to treat the tail water of livestock and poultry waste water, and the pollutant concentration in the waste water is very low originally. , the enrichment of pollutants by the electrode not only does not affect the function of the electrode, but also facilitates the subsequent reactions.

In the cathode chamber, the antibiotics that are not completely removed can also be adsorbed by the electrode, and secondly, the copper ions will be removed by reduction reaction on the electrode.

Experimental example 1:

Taking the complex solution of 10 ppm copper ions and tetracycline as an example, three-dimensional graphene aerogels are used as electrodes in both the cathode chamber and the anode chamber to remove pollutants under the condition of applied voltage.

The first step, put the complex solution in the anode compartment, put the electrolyte (can be deionized water) in the cathode compartment, the anode compartment electrode is three-dimensional graphene aerogel at this moment, and the cathode compartment electrode is a graphite rod. At 1.8V voltage for 4h, the removal rate of tetracycline in the anode chamber can reach 91%, and the removal rate of copper ions can reach 48% (the removal of tetracycline includes electrode adsorption and electrocatalytic degradation, and the removal of copper ions is graphite. due to the adsorption of alkene electrodes).

In the second step, the treatment solution of the anode chamber is transferred to the cathode chamber. At this time, the anode chamber is supplemented with a new complex solution. Both the cathode chamber and the anode chamber use three-dimensional graphene aerogel as electrodes, and react at a voltage of 1.8V for 2 hours. , tetracycline and copper ions were all removed (as shown in Figure 4).

In the above experiments, the first step of treatment is to remove the complexes in the contaminated liquid of the anode chamber. The cathode chamber solution and electrodes (graphite rods) only play a conductive role. In order to save costs, the cathode chamber is only used when treating the waste liquid. Graphene is used as electrodes, otherwise cheap graphite rods are used as materials for conducting electricity.

Example 2:

When the complex solution is 20 ppm, the first step is consistent with Example 1, and the removal rate of tetracycline reaches 65% and the removal rate of copper ions reaches 75% after 4 hours. In the second step, the same operation as the second step in Example 1, the removal rate of tetracycline reached 92% after 4 hours, and the copper ions were completely removed. In the third step, the second-step cathode treatment solution was transferred to the anode chamber, and the tetracycline was completely removed after 2 h (as shown in Figure 4).

Example 3:

When the complex solution is 50 ppm, the operation is the same as when the solution is 20 ppm. The solution is circulated between the cathode compartment and the anode compartment. After the complex solution is treated three times in the anode compartment and twice in the cathode compartment, the removal rate of tetracycline is Up to 80%, copper ions can be completely removed (as shown in Figure 4).

The above experiments make full use of the isolation of the experimental device (the function is to separate the electrochemical cathode and anode, so that it can treat pollutants separately. From the overall point of view, under the same conditions, the double-chamber reactor has stronger processing capacity), the adsorption of electrode materials (the role is, ① remove pollutants by adsorption, and increase the way of removing pollutants, ② Enriching pollutants, speeding up the subsequent reaction rate) and electrical conductivity (the role is to play a conductive role in the system and play an electrochemical role), diversify the removal methods of pollutants, and the yin and yang poles perform their respective duties, the system can be cycled The reaction removes different types of pollutants, effectively improving the overall reaction rate.

The device isolation and the particularity of the electrodes of the present invention are not easy for researchers in the field to think of, because in the field of electrochemical oxidation, most researchers focus on the study of electrode materials, increasing the number of reaction chambers to improve the The point of reaction efficiency has not been put before the public; and three-dimensional graphene aerogels are generally used as a substrate or as an intermediate to be compounded with other materials, and more use its conductivity and three-dimensional structure to make other materials. Has better conductivity and dispersion. But like the present invention, there is no one that is directly used as an electrode.

Since the conventional single-chamber reactor is used in the prior art, the production capacity of the system is low during the reaction process. However, the present invention adopts a dual-chamber reactor (as shown in Figure 3), and its greatest advantage is that it can achieve a higher single-chamber production capacity without increasing energy. The processing capacity of the chamber reactor is higher.

Secondly, in the prior art, the electrode is made of metal aluminum, and the electrode plate is easily passivated, which will cause the reaction rate to decrease in the later stage. The electrode used in the present invention is a three-dimensional graphene aerogel, which is non-metal, and will not cause a decrease in the reaction rate due to electrode passivation. Moreover, in the prior art, the removal method of pollutants is only redox reaction. In the present invention, because the electrode has strong adsorption performance, it can not only remove pollutants by adsorption, increase the pollutant removal path, but also enrich the pollutants, improve the mass transfer efficiency of the system, and increase the rate of subsequent reactions to a certain extent.

Finally, in the prior art, a three-dimensional electrode system composed of a cathode plate, an anode plate and a particle electrode is used. Although this system can improve the reaction rate of the traditional two-dimensional electrode system, it requires the bypass current and short-circuit current in the reaction to be minimized. Possibly less, so it has higher requirements for particle electrodes, and the electrochemical process is relatively complicated. However, the present invention still adopts a two-dimensional electrode system, which can not only improve the reaction rate, but also the electrolysis process is relatively simple.

The processing system provided by the present invention has the following characteristics:

①The anode reaction chamber and the cathode reaction chamber perform their respective duties, which can remove antibiotics and heavy metals in a targeted manner; ②Increasing the reaction chamber of the system can improve the processing efficiency of the system; ③The electrode is a non-metallic electrode, which will not be dull during the reaction process It will not affect the treatment in the later stage of the reaction process; ④The electrode has adsorption, not only can remove copper ions and antibiotics through redox reaction, but also can remove pollutants through adsorption, which increases the removal path of pollutants; ⑤The electrode can both The pollutants can be removed by adsorption, and the pollutants can also be enriched by adsorption, which is beneficial to the later reaction.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be The technical solutions described in the foregoing embodiments are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (1)

1. A livestock and poultry wastewater tail water treatment system is characterized by comprising a reactor for treating livestock and poultry wastewater tail water, wherein a reaction chamber of the reactor is divided into a cathode reaction chamber and an anode reaction chamber by a cation exchange membrane, and graphene aerogel is respectively used as a cathode electrode and an anode electrode of the cathode reaction chamber and the anode reaction chamber;

when the livestock and poultry wastewater tail water is treated, firstly, the livestock and poultry wastewater tail water reacts in an anode reaction chamber to remove antibiotics and part of copper ions, and certain electrolyte is added in a cathode reaction chamber to ensure that the anode reaction chamber normally reacts; then the tail water treated by the anode reaction chamber is transferred to the cathode reaction chamber to remove copper ions and part of residual antibiotics, and meanwhile, the anode reaction chamber continues to treat a new round of livestock and poultry wastewater tail water.

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