CN111204852A

CN111204852A - Livestock and poultry wastewater tail water treatment system

Info

Publication number: CN111204852A
Application number: CN202010054518.9A
Authority: CN
Inventors: 龙琭璐; 白昌伟
Original assignee: Sichuan Agricultural University
Current assignee: Sichuan Agricultural University
Priority date: 2020-01-17
Filing date: 2020-01-17
Publication date: 2020-05-29
Anticipated expiration: 2040-01-17
Also published as: CN111204852B

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 by 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

Livestock and poultry wastewater tail water treatment system

Technical Field

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

Background

In the development of livestock and poultry industry, antibiotics and heavy metal ions are often used as feed additives to be added into feed, and the addition amount is far beyond the absorption amount 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, the antibiotics and heavy metals are not easily removed in the environment, and the antibiotics and heavy metal ions form a complex compound, which increases the removal difficulty and also accumulates in the environment, thereby causing serious environmental pollution, and the antibiotics and heavy metals remaining in the environment have attracted high attention because of potential long-term adverse threats to human health and natural ecosystem.

Up to now, the methods for treating antibiotics and heavy metal complexes in livestock and poultry wastewater mainly include physical treatment, biological treatment and advanced oxidation. The physical treatment method mainly has the problems of strong characteristic of the required adsorbent, more adsorbent consumption, long contact time with the pollutants and the like, and the method only simply transfers the pollutants from a liquid phase to a solid phase and does not really remove the pollutants, and the subsequent treatment of the deactivated adsorbents is troublesome, so the method is not suitable for removing the composite pollutants. When the biological treatment method is adopted to remove the composite pollutants, the defects are that the treatment period is long, the toxicity of the antibiotics is uncertain after treatment, and the microbial cells are easy to generate an antibacterial effect on the antibiotics, so that the pollutants escape from the treatment and remain in the water body. Biological methods are therefore also not ideal for the treatment of complex contaminants.

In recent years, electrochemical Advanced oxidation technology (AEOP) is one of the wastewater treatment technologies that have attracted much attention, and Electrolysis (Electrolysis) is a process of causing redox reactions on a cathode and an anode by passing an electric current through an electrolyte solution. The existing research shows that the electrochemical method has great potential in the aspect of treating livestock wastewater, the research takes the electrochemical method as a technical core and adopts a multi-polarity packed bed (granular active carbon is filled between electrode plates as a particle electrode and no diaphragm). The electrolytic bath body is an organic glass bath, the electrode plate adopts a cathode and anode homogeneous aluminum plate electrode, the particle electrode is activated carbon, the reaction device is shown in figure 1, and the device comprises a direct current stabilized voltage power supply 1, an anode plate 2, a particle electrode 3, a cathode plate 4, a valve 5 and a water outlet 6. During the reaction process, the antibiotics can be oxidized and removed near the anode plate through two oxidation modes, namely direct electrochemical oxidation and indirect electrochemical oxidation. During the reaction process, the antibiotics can be oxidized and removed by two oxidation modes, namely direct electrochemical oxidation and indirect electrochemical oxidation, and the principle is shown in figure 2. And the heavy metal ions can be reduced and removed near the cathode plate, and the principle is as follows:

M^Z++Ze^-→M⁰(M-Cu, Zn, Pb, etc.)

Although the electrochemical advanced oxidation technology has good effect on treating livestock wastewater, the electrochemical advanced oxidation technology also has some problems that firstly, the electricity is extremely easy to passivate, and the reaction rate in a later-period system is reduced; secondly, as the electrochemical oxidation reaction proceeds, the organic pollutants in the system are gradually reduced, which affects the mass transfer rate in the system and further causes the reaction rate to decrease in the later period. Especially, when the livestock wastewater tail water is treated, the traditional electrochemical oxidation method is greatly limited, the livestock wastewater tail water is the water which reaches the livestock wastewater discharge standard after the livestock wastewater is subjected to physical, chemical or biological treatment, but in the current livestock wastewater discharge situation, even if the livestock wastewater discharge standard is reached, the wastewater still contains part of antibiotics and heavy metal ions. The most typical characteristics of the chemical oxidation method are that the concentration is low, so that the mass transfer rate of a system is limited during the post-treatment, in view of the potential hazard of antibiotics and heavy metal ions to the environment, the advanced treatment of the livestock wastewater tail water is imperative, when the tail water is treated by using the traditional electrochemical oxidation method, the problems of low current efficiency, insufficient energy utilization and the like are caused (when the tail water is treated by advanced oxidation, the mass transfer resistance of low-concentration pollutants in the tail water is limited, so that the current efficiency and the treatment effect are influenced), and the pollutant removal mode of the traditional electrochemical oxidation method is only oxidation-reduction reaction, so that the efficiency is relatively low. Therefore, we must improve on the original basis.

Disclosure of Invention

The invention aims to solve the defects of the prior art and provides a livestock and poultry wastewater tail water treatment method, which utilizes the adsorbability of an electrode and the particularity of a reaction device (a double-chamber reactor), and the adsorption effect of the electrode can enrich pollutants so as to reduce the influence of mass transfer; and the double-chamber reactor can improve the reaction efficiency.

Has the advantages that:

first, in the prior art, either physical treatment, biological treatment or advanced oxidation processes, which are performed before the wastewater is discharged, do not perform advanced treatment of the tail water. The invention mainly aims at advanced treatment of tail water discharged by livestock wastewater, so that the aim of zero discharge or near zero discharge of antibiotics and heavy metal ions in the livestock wastewater is fulfilled. The research shows that the invention has better removal effect on complex solution of antibiotics and heavy metals, and the antibiotics and the heavy metals can be completely removed in a low concentration range (10ppm and 20 ppm); in the high concentration range (50ppm), heavy metals can be completely removed, and the antibiotic removal rate is as high as 82%.

Second, the present invention employs a dual chamber reactor, which has higher processing efficiency per unit time than a single chamber reactor.

And thirdly, the electrode used in the experiment has simple preparation method and mild reaction conditions, but has good electrolytic effect and can not be passivated.

Fourthly, the invention diversifies the removal mode of the pollutants in the same time unit, and improves the reaction rate.

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

Sixthly, when the method is used for treating the actual livestock wastewater tail water, the removal rate of TOC can reach 63%, and the removal rate of copper ions can reach 88%.

Drawings

FIG. 1 is a schematic view of a prior art electrochemical process apparatus;

FIG. 2 is a schematic diagram of a prior art electrochemical reaction; wherein (a) is a direct electrochemical oxidation schematic diagram; (b) is a schematic diagram of indirect electrochemical oxidation;

FIG. 3 is a schematic view of a reaction apparatus of the present invention;

FIG. 4 is a graph showing the degradation of tetracycline and copper ion complexes treated at different concentrations in the experiment according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention are described clearly and completely below, and it is obvious that the described embodiments are some, 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.

Fig. 3 is a schematic diagram of a reaction apparatus of the present invention, and as shown in fig. 3, the system of the present invention employs a dual-chamber reactor (a cathode chamber and an anode chamber are separated by a cation exchange membrane, and an anode and a cathode of an electrochemical reaction are separated to form a separate anode chamber and cathode chamber) for treating livestock and poultry wastewater tail water, and graphene aerogel is used as the cathode and the anode to treat pollutants.

In the anode chamber, three antibiotic removing paths are provided, wherein the first antibiotic removing path is directly adsorbed by an electrode, the second antibiotic removing path is directly adsorbed by an electrode, the third antibiotic removing path is directly oxidized by an indirect oxidation reaction, and the third antibiotic removing path is indirectly oxidized by the indirect oxidation reaction, and the efficiency of removing the pollutants is not influenced by the fact that the electrode directly adsorbs the pollutants in the first step, because the adsorbability of the ① graphene aerogel electrode is good, ② the invention is used for treating tail water of livestock and poultry wastewater, the concentration of the pollutants in the wastewater is low originally, and the pollutants are enriched by the electrode, so that the functions of the electrode are not influenced, and the subsequent reaction is facilitated.

In the cathode chamber, antibiotics which are not completely removed can be adsorbed by the electrode, and secondly, copper ions are reduced on the electrode and removed.

Experimental example 1:

taking a complex solution of copper ions and tetracycline of 10ppm as an example, the cathode chamber and the anode chamber both use three-dimensional graphene aerogel as electrodes, and pollutants are removed under the condition of an applied voltage.

Firstly, complex solution is put into the anode chamber, electrolyte (which can be deionized water) is put into the cathode chamber, the anode chamber electrode is three-dimensional graphene aerogel, the cathode chamber electrode is a graphite rod, the reaction is carried out for 4 hours under the voltage of 1.8V, the tetracycline removal rate of the anode chamber can reach 91 percent, and the copper ion removal rate can reach 48 percent (wherein the tetracycline removal comprises two parts of adsorption and electrocatalytic degradation of the electrode, and the copper ion removal is caused by the adsorption of the graphene electrode).

And secondly, transferring the anode chamber treatment solution to a cathode chamber, supplementing a new complex solution to the anode chamber, reacting for 2 hours at a voltage of 1.8V by using the three-dimensional graphene aerogel as electrodes in the cathode chamber and the anode chamber, and completely removing tetracycline and copper ions (shown in figure 4).

In the above experiment, the first step of treatment is to remove the complex in the anode chamber contaminated liquid, the cathode chamber solution and the electrode (graphite rod) only function as electric conduction, and in order to save cost, the cathode chamber only uses graphene as an electrode when the waste liquid is treated, otherwise, the inexpensive graphite rod is used as a material for electric conduction.

Example 2:

when the complex solution was 20ppm, the first step was identical to example 1, and the tetracycline removal rate after 4 hours was 65% and the copper ion removal rate was 75%. In the second step, the same operation as in the second step of example 1 was carried out, and after 4 hours, the tetracycline removal rate reached 92%, and copper ions were completely removed. And thirdly, transferring the cathode treatment solution in the second step to the anode chamber, and completely removing the tetracycline after 2h (shown in figure 4).

Example 3:

when the complex solution was 50ppm, the operation was identical to that when the solution was 20ppm, the solution was circulated between the cathode chamber and the anode chamber, and after the complex solution was treated three times in the anode chamber and twice in the cathode chamber, the tetracycline removal rate reached 80% and the copper ions could be completely removed (as shown in FIG. 4).

Above experiment make full use of experimental apparatus's isolation (the effect is just to separate electrochemical cathode and anode, make it can handle the pollutant alone, its biggest advantage is in can reaching higher single-room productivity under the condition of not increasing the energy, on the whole, under the same condition, the throughput of two room reactors is stronger, electrode material's adsorptivity (effect is, ① gets rid of the pollutant through adsorbing, increase the route of getting rid of the pollutant, ② enrichment pollutant, accelerate follow-up reaction rate) and electric conductivity (effect is, play the electrically conductive effect in the system, play the electrochemistry effect), make the removal mode pluralism of pollutant, and the negative and positive poles take its own role respectively, the system can loop reaction get rid of different class of pollutant, effectual holistic reaction rate that has promoted.

The device isolation and the specificity of the electrode of the present invention are points that are not easily imaginable to researchers in the field, because in the field of electrochemical oxidation, the focus of researchers is mostly focused on the research of electrode materials, and the point of increasing the number of reaction chambers to improve the reaction efficiency is not put to the public at present; and the three-dimensional graphene aerogel is generally used as a substrate or an intermediate and compounded with other materials, and the conductivity and the three-dimensional structure of the three-dimensional graphene aerogel are utilized to enable the other materials to have better conductivity and dispersibility. But like the present invention does not.

Because the prior art adopts the traditional single-chamber reactor, the production capacity of the system is lower in the reaction process. The present invention, however, uses a dual chamber reactor (as shown in fig. 3), which has the greatest advantage of achieving higher single chamber throughput without increasing energy, and overall, the processing capacity of the dual chamber reactor is higher under the same conditions.

Secondly, in the prior art, the electrode is made of metal aluminum, and an electrode plate is easy to passivate, so that the later reaction rate is reduced. The electrode adopted by the invention is the three-dimensional graphene aerogel which is non-metal, so that the reaction rate is not reduced due to electrode passivation. In the prior art, the pollutant removal mode is only oxidation-reduction reaction, and in the invention, because the electrode has stronger adsorption performance, the pollutant can be removed through adsorption, a pollutant removal path is increased, the pollutant can be enriched, the mass transfer efficiency of the system is improved, and the rate of subsequent reaction is improved to a certain extent.

Finally, the prior art adopts a three-dimensional electrode system composed of a cathode plate, an anode plate and a particle electrode, which can improve the reaction rate of the traditional two-dimensional electrode system, but requires that the bypass current and the short-circuit current in the reaction are as little as possible, so that the requirement on the particle electrode is high, and the electrochemical process is relatively complex. However, the invention still adopts a two-dimensional electrode system, which not only can improve the reaction rate, but also has relatively simple electrolytic process.

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

① the anode reaction chamber and the cathode reaction chamber respectively play their roles and can remove antibiotics and heavy metals in a targeted manner, ② the reaction chamber of the system is increased to improve the treatment efficiency of the system, ③ the electrode is a non-metal electrode which can not be passivated in the reaction process and can not influence the treatment in the later stage of the reaction process, ④ the electrode has adsorbability and can not only remove copper ions and antibiotics through oxidation-reduction reaction, but also remove pollutants through adsorption and increase the removal path of pollutants, ⑤ the electrode can remove pollutants through adsorption and can also enrich pollutants through adsorption, which is beneficial to the reaction in the later stage.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. The 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.