CN108773878A - A kind of landfill leachate bio-chemical effluent treatment reactor and method - Google Patents

Abstract

The invention provides a biochemical effluent treatment reactor and method for landfill leachate, relates to the technical field of sewage treatment, and solves the technical problem that COD and TN cannot be removed simultaneously in the landfill leachate biochemical water. It includes an electrochemical flocculation device that absorbs macromolecular refractory organic matter to form reducing sludge and converts nitrate nitrogen into ammonia nitrogen, an electrochemical oxidation device that generates available chlorine and reacts with the ammonia nitrogen to eliminate the ammonia nitrogen, and a first pump. The electrochemical flocculation device is provided with a first solution outlet and a first sludge outlet, and the electrochemical oxidation device is provided with a first solution inlet; the inlet and outlet of the first pump correspond to the outlet of the first solution and the outlet of the first pump respectively. The first solution inlet is connected and communicated, and the reducing sludge flows out from the first sludge outlet.

Description

Reactor and method for biochemical effluent treatment of landfill leachate

technical field

The invention relates to the technical field of sewage treatment, in particular to a biochemical effluent treatment reactor and method for landfill leachate.

Background technique

At present, whether in developed or developing countries, municipal solid waste MSW is usually disposed of by landfill because it is an economical and quick method. However, a series of physical, chemical and biological actions of these solid wastes through rainwater leaching and the landfill system itself will produce a high-concentration organic wastewater called landfill leachate. In recent years, scholars at home and abroad have conducted a lot of research on landfill leachate treatment, such as microbial treatment methods, membrane technology and advanced oxidation technology. Among these existing treatment processes, microbial treatment is considered to be the most promising treatment method due to its cost-effectiveness and has been widely promoted. However, it is difficult for microorganisms to process macromolecular antioxidant organic substances (such as humic acid and fulvic acid) and the soluble microbial degradation products produced by metabolism during microbial reactions have a positive correlation with the increase in their own toxicity during landfill leachate treatment. At the same time, because landfill leachate often contains high concentrations of ammonia nitrogen, it will seriously inhibit the activity of ammonia oxidizing bacteria and nitrite oxidizing bacteria, especially the inhibition of nitrite oxidizing bacteria is the most obvious. Because of this, microbial treatment often This makes the system accumulate high concentration of nitrite nitrogen, making it difficult to remove total nitrogen. Therefore, the effluent treated by the microbial treatment process (biochemical effluent of landfill leachate). Still contain a high concentration of chemical oxygen demand COD and total nitrogen TN. If these harmful substances are not disposed of properly, they will cause serious harm to the health of residents and the ecological system. Therefore, further advanced treatment is still required for the biochemical effluent of landfill leachate.

Among the treatment processes developed in the past for the biochemical effluent of landfill leachate, the nanofiltration reverse osmosis process has been widely used due to its good reverse osmosis effluent quality. However, during the operation of the nanofiltration reverse osmosis process, a more harmful high-concentration wastewater called reverse osmosis concentrate will be produced. At present, the treatment of reverse osmosis concentrate is to continue to pour it back into the landfill. Long-term operation will not only seriously endanger the normal operation of the bioreactor, but also cause serious environmental risks during the landfill process, such as the growth of germs. At the same time, the concentration polarization phenomenon and membrane clogging often lead to short service life of the reverse osmosis membrane, so the nanofiltration reverse osmosis process usually incurs high operating costs. In addition, the advanced oxidation process is an efficient high-concentration wastewater treatment method. However, the dependence of these advanced oxidation processes on the pH value determines that it is difficult to promote on an engineering scale.

In recent years, the electrochemical process is considered to be the most promising biochemical effluent treatment process for landfill leachate due to its stability, strong organic mineralization ability and simple operation. It has been confirmed that the removal of SS and macromolecular refractory organics can be achieved by electrocoagulation; the decomposition of macromolecular organics (such as humus) can be achieved by electrochemical oxidation; Removal of inorganic ions such as hexavalent chromium and nitrate. Scholars at home and abroad have studied the electrochemical treatment of complex sewage. Seeger et al. studied the electrocoagulation process for landfill leachate, which is practical in COD removal. However, the disadvantage is that the electrocoagulation process is difficult to achieve the removal of ammonia nitrogen. Fernandes et al. used Ti/Pt/PbO ₂ , Ti/Pt/SnO ₂ -Sb ₂ O ₄ anode electrochemical oxidation to treat landfill leachate, and obtained good COD and ammonia nitrogen treatment effects, but the disadvantage is that the effluent often accumulates high Concentration of available chlorine, and the oxidation process is difficult to achieve efficient removal of nitrate. In the inventor's previous research, a "DSA+Fe+Cu/Zn" electrochemical system based on iron grid polarized electrodes was constructed to enhance the removal of COD and nitrate. The results showed that in the presence of iron grid, the electrode The nitrate removal capacity of the chemical system has been significantly improved, however, it is still difficult to achieve the removal of available chlorine in the effluent.

In addition, scholars at home and abroad have also conducted research on the construction of electrochemical systems (one-stage (single electrolyzer structure) or multi-stage (multiple electrolyzer structure)). Among them, Fernandes et al. applied electrocoagulation combined with anodic oxidation (EC+AO) The two-stage process degrades landfill leachate and achieves a good COD removal effect. But there are also the following problems: (1) Different from the indirect oxidation based on DSA anode (for example: Ti/RuO ₂ , Ti/IrO ₂ or Ti/PbO ₂ ), in the anodic oxidation process of BDD anode, the removal rate of ammonia nitrogen is less than The removal rate of COD is related to the nature of the BDD anode itself, because the BDD anode is more inclined to generate hydroxyl radicals, but the removal of ammonia nitrogen mainly depends on the oxidation of available chlorine. Due to the slow removal rate of ammonia nitrogen, the removal efficiency of total nitrogen is reduced. ; (2) The BDD electrode promotes the accumulation of nitrate, which is unfavorable for the removal of total nitrogen; (3) Due to the expensive cost of the BDD anode itself, its manufacture is used in practical engineering; (4) In the effluent of the EC+AO system , Available chlorine is also difficult to remove. Ding et al. used iron and Ti/RuO ₂ -IrO ₂ as anodes in a single reactor at the same time, and realized electrochemical flocculation and electrochemical oxidation processes in a single electrolytic cell. In this system, the treatment of landfill leachate biochemical effluent , obtained a good removal effect of COD, ammonia nitrogen and total phosphorus. However, in a single reactor, it is difficult to efficiently remove nitrate. In addition, since the kinetic constant of the reaction between Fe ²⁺ and available chlorine is much greater than that of COD and available chlorine, the Fe leached from the anode ²⁺ will hinder the improvement of the oxidation efficiency of the system. Also because of this, the electrochemical process of a single electrolyzer is difficult to simultaneously remove TN and COD in complex wastewater (especially wastewater with high nitrate nitrogen content). Among the published related patents on the electrochemical treatment of landfill leachate, the Chinese patent application number 201410766657.9 discloses the use of "electrochemical oxidation + collaborative flocculation" to treat landfill leachate, and achieved good results in the removal of COD and ammonia nitrogen . However, for the high concentration of nitrate nitrogen (nitrate nitrogen or nitrite nitrogen) in the influent, it is difficult to achieve efficient removal of total nitrogen through a single electrochemical oxidation. Li et al. constructed and compared the performance of a one-stage electrochemical system based on Ti/IrO _{2 -Pt} , Ti/RuO ₂ -Pt and Ti/Pt electrodes to treat nitrate. Kuang et al. Mesh + 3D perforated iron cathode" electrochemical system with one-stage structure strengthens the removal of nitrate wastewater. However, in the studies of Li and Kuang et al., there is the problem of low current efficiency of nitrate removal (<10%), that is, the inhibition of cathodic reduction by electrochemical oxidation (direct oxidation and indirect oxidation) in the same electrolyzer. Since it is difficult for a one-stage electrochemical process to overcome the mutual reduction of redox performance caused by the bipolar effect of its own reactor, it is necessary to realize different electrochemical processes by constructing a multi-stage electrochemical process in order to improve the current efficiency.

In summary, the shortcomings of the current electrochemical process are mainly related to the electrochemical oxidation process. First, the available chlorine produced by the electrochemical oxidation process has a positive effect on promoting COD removal, but its presence will seriously hinder the cathodic reduction of nitrate, which is related to the cathodic reduction pathway of nitrate. Therefore, due to the mutual restriction of COD and nitrate removal, it is difficult to achieve the simultaneous removal of COD and TN by pure electrochemical oxidation process. Second, the high concentration of available chlorine produced in the electrochemical oxidation process has strong cytotoxicity, but its natural decay often takes several weeks, which makes it difficult to discharge the effluent from the pure electrochemical oxidation process to urban sewage treatment plants for final treatment. deal with. It is precisely because of this that it is difficult to promote the electrochemical process in the field of landfill leachate biochemical effluent treatment, which also limits the development of electrochemical water treatment technology.

In addition, the arrangement of electrodes and the phase separation of electrochemical reactors also have a certain impact on the performance of electrochemical processes and the ease of process operation and maintenance. Generally, electrode arrangement can be divided into series arrangement and parallel arrangement. Compared with the parallel arrangement, the series arrangement needs to provide a higher potential difference under equal current conditions, which will result in higher power consumption. Therefore, the parallel arrangement of the electrode plates is more conducive to the optimization of energy efficiency. In the past research, Ilhan et al. applied electrocoagulation treatment of landfill leachate in a batch experimental reactor with two parallel electrodes, and obtained a COD removal rate of 35%. Veli et al. applied a continuous reactor with fourteen parallel electrodes and obtained a COD removal rate of 90%. Fernandes et al. applied a batch reactor with two parallel electrodes and obtained a COD removal rate of 42%. However, in previous studies, there are the following problems: (1) Fe anodes used as sacrificial electrodes are often paired with cathodes in parallel, which is unfavorable for the effective use of Fe anodes; (2) the outlet of the batch reactor is generally It is set parallel to the liquid surface, which makes the separation of mud and water incomplete due to the existence of surface adsorption at the mud-water interface, which eventually leads to high sludge moisture content.

Contents of the invention

The purpose of the first aspect of the present invention is to provide a landfill leachate biochemical effluent treatment reactor to solve the technical problem in the prior art that COD and TN cannot be removed simultaneously in the landfill leachate biochemical water. The many technical effects that can be produced by the preferred technical solutions among the many technical solutions provided by the present invention are described in detail below.

To achieve the above object, the present invention provides the following technical solutions:

The biochemical effluent treatment reactor for landfill leachate provided by the invention includes an electrochemical flocculation device that absorbs macromolecular refractory organic matter to form reducing sludge and converts nitrate nitrogen into ammonia nitrogen, and generates available chlorine to react with the ammonia nitrogen to The electrochemical oxidation device and the first pump for eliminating the ammonia nitrogen, the electrochemical flocculation device is provided with the first solution outlet and the first sludge outlet, the electrochemical oxidation device is provided with the first solution inlet; the first pump's The inlet and the outlet are respectively connected and communicated with the first solution outlet and the first solution inlet, and the reducing sludge flows out from the first sludge outlet.

The beneficial effect of the present invention is that through the arrangement of the electrochemical flocculation device, the electrochemical oxidation device and the first pump, after the reaction and precipitation of the biochemical aqueous solution in the electrochemical flocculation device is completed, the macromolecular refractory organic matter in the biochemical aqueous solution is absorbed and degraded. Reducing sludge is formed, and the nitrate nitrogen in the biochemical aqueous solution is converted into ammonia nitrogen and exists in the solution, and the solution is transported to the electrochemical oxidation device through the first pump to eliminate ammonia nitrogen. Therefore, the elimination of macromolecular antioxidant organic compounds and ammonia nitrogen can be realized at the same time, thereby alleviating the pressure of subsequent treatment.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, the treatment reactor also includes an effective chlorine elimination device, a second pump, and a third pump. The effective chlorine elimination device is provided with a second solution inlet and a sludge inlet, and the electrochemical oxidation device is provided with a second Solution outlet, the inlet and outlet of the second pump are respectively connected and communicated with the second solution outlet and the second solution inlet; the inlet and outlet of the third pump are respectively corresponding to the first sludge The outlet is connected and communicated with the sludge inlet.

Further, in the treatment reactor, the bottom of the electrochemical flocculation device and the electrochemical oxidation device adopts a conical sludge bucket, and the first solution outlet and the second solution outlet are connected to the The outer wall of the sludge bucket is vertical.

Further, in the treatment reactor, the first solution outlet and the second solution outlet respectively correspond to the distance from the first sludge outlet and the second sludge outlet and the corresponding distance to the sludge The distance ratio of the upper edge of the bucket is 1:9.

Further, in the treatment reactor, the electrochemical flocculation device and the electrochemical oxidation device have a plurality of cross-connected cathode plates and anode plates placed parallel to the water flow direction; the cathode plates and the anode plates are The spacing is 5-15mm.

Further, in the treatment reactor, the anode plate of the electrochemical flocculation device is made of iron and has a plate structure, and the cathode plate is made of any material such as iron, aluminum, copper or nickel and has a mesh structure.

Further, in the treatment reactor, the electrochemical oxidation device has a plate-shaped coated titanium anode plate, and the cathode plate is made of any material such as iron, aluminum, copper or nickel and has a mesh structure.

The object of the second aspect of the present invention is to provide a biochemical effluent treatment method of landfill leachate to solve the technical problem in the prior art that COD and TN cannot be removed simultaneously in the biochemical water of landfill leachate. The many technical effects that can be produced by the preferred technical solutions among the many technical solutions provided by the present invention are described in detail below.

To achieve the above object, the present invention provides the following technical solutions:

A biochemical effluent treatment method for landfill leachate provided by the present invention is realized according to the biochemical effluent treatment reactor for landfill leachate according to any one of claims 1 to 7, comprising the following steps:

S1, the macromolecular refractory organic matter in the biochemical effluent solution is adsorbed by the flocs produced by the anode plate of the electrochemical flocculation device to form reducing sludge; S2, the nitrate nitrogen in the biochemical effluent solution is in the The cathode plate reduction of the electrochemical flocculation device is converted into ammonia nitrogen; S3, the solution containing ammonia nitrogen in step S2 enters the electrochemical oxidation device that can generate available chlorine, and the ammonia nitrogen reacts with the available chlorine to form ammonia nitrogen-free The first solution; where S1 and S2 are executed simultaneously.

Further, the treatment method also includes step 4, mixing and reacting the reducing sludge and the first solution to eliminate the remaining available chlorine in the first solution, and the reducing sludge Contains ferrous hydroxide.

Further, in the treatment method, precipitation treatment is required in the steps S1, S4 and S3.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic diagram of the structure of the treatment reactor of the present invention.

In the figure 1-electrochemical flocculation device, 2-electrochemical oxidation device, 3-first pump, 4-effective chlorine elimination device, 5-second pump, 6-third pump, 7-fourth pump, 11-the first 1 solution outlet, 12-first sludge outlet, 13-iron anode plate, 14-first cathode plate, 15-first DC power supply, 21-first solution inlet, 22-second solution outlet, 23- Second sludge outlet, 24-coated titanium anode plate, 25-second cathode plate, 26-second DC power supply, 41-second solution inlet, 42-sludge inlet, 43-third solution outlet, 44 - Third sludge outlet.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Apparently, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other implementations obtained by persons of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

The first aspect of the present invention provides a biochemical effluent treatment reactor for landfill leachate, including an electrochemical flocculation device that absorbs macromolecular refractory organic matter to form reducing sludge and converts nitrate nitrogen into ammonia nitrogen. 1. Generating available chlorine and ammonia nitrogen The electrochemical oxidation device 2 and the first pump 3 react to eliminate ammonia nitrogen. The electrochemical flocculation device 1 has a first solution outlet 11 and a first sludge outlet 12 . The electrochemical oxidation device 2 has a first solution inlet 21 . The inlet and outlet of the first pump 3 are respectively connected and communicated with the first solution outlet 11 and the first solution inlet 21 . The reducing sludge flows out from the first sludge outlet 12 .

Specifically, as shown in FIG. 1 , wherein FIG. 1 is a schematic structural diagram of the treatment reactor of the present invention. The electrochemical flocculation device 1 , the electrochemical oxidation device 2 and the first pump 3 can be connected and communicated by rubber tubes. The first pump 3 is used to transport the solution reacted in the electrochemical flocculation device 1 to the electrochemical oxidation device 2 to provide power. Both the electrochemical flocculation device 1 and the electrochemical oxidation device 2 can use fixed-bed reactors.

Through the arrangement of the electrochemical flocculation device 1, the electrochemical oxidation device 2 and the first pump 3, after the reaction and precipitation of the biochemical aqueous solution in the electrochemical flocculation device 1 is completed, the macromolecular refractory organic substances in the biochemical aqueous solution are adsorbed and form a reduced The nitrate nitrogen in the aqueous solution is biochemically transformed into ammonia nitrogen and exists in the solution, and the solution is transported to the electrochemical oxidation device 2 through the first pump 3 to eliminate ammonia nitrogen. Therefore, the elimination of macromolecular refractory organic matter and ammonia nitrogen can be realized at the same time, so as to realize the elimination of COD and TN and relieve the pressure of subsequent treatment.

As an optional embodiment, an effective chlorine elimination device 4 , a second pump 5 and a third pump 6 are also included. The available chlorine elimination device 4 has a second solution inlet 41 and a sludge inlet 42 . The electrochemical oxidation device 2 opens a second solution outlet 22 . The inlet and outlet of the second pump 5 are respectively connected and communicated with the second solution outlet 22 and the second solution inlet 41 . The inlet and outlet of the third pump 6 are respectively connected and communicated with the first sludge outlet 12 and the sludge inlet 42 .

Specifically, as shown in FIG. 1 , the reducing sludge generated by the flocculation of the biochemical aqueous solution in the electrochemical flocculation device 1 is transported to the available chlorine elimination device 4 through the third pump 6 . The solution containing residual available chlorine formed after the reaction in the electrochemical oxidation device 2 is transported to the available chlorine elimination device 4 through the second pump 5 . The reducing sludge is mixed with the solution containing the remaining available chlorine for dechlorination reaction, so that the available chlorine can be eliminated and the toxicity of the effluent can be reduced.

Certainly, a second sludge outlet 23 may also be provided on the electrochemical oxidation device 2 for transporting the reducing sludge produced by the reaction in the electrochemical oxidation device 2 to the available chlorine elimination device 4 through the third pump 6 .

The available chlorine elimination device 4 is also provided with a third solution outlet 43 and a third sludge outlet 44 for outputting the reacted solution and sludge respectively. A fourth pump 7 is also included, and the inlet of the fourth pump 7 is connected and communicated with the third sludge outlet 44 for outputting the reacted sludge.

In the available chlorine elimination device 4, since the reducing sludge with ferrous hydroxide as the main component can be mainly generated in the electrochemical flocculation device 2, the excess available chlorine generated in the reducing sludge and the electrochemical oxidation device 2 Oxidation-reduction reactions occur to remove excess available chlorine. The main reactions are as follows:

2Fe(OH) ₂ +ClO ^- +H ₂ O＝2Fe(OH) ₃ +Cl ^-

That is to say, the available chlorine elimination device 4 can play a role in elimination of available chlorine, precipitation of sludge and separation of solution.

Further, the bottoms of the electrochemical flocculation device 1 and the electrochemical oxidation device 2 adopt conical sludge hoppers. Both the first solution outlet 11 and the second solution outlet 22 are perpendicular to the outer wall of the sludge hopper.

Specifically, as shown in FIG. 1 , in order to facilitate the output of sludge, a conical sludge hopper is installed under the electrochemical flocculation device 1 , the electrochemical oxidation device 2 and the available chlorine elimination device 4 . The sludge settles into the sludge hopper. The first sludge outlet 12 and the second sludge outlet 23 are opened at the bottom of the sludge bucket.

Both the first solution outlet 11 and the second solution outlet 22 are arranged vertically to the outer wall of the sludge hopper, so that the mud-water separation can be better achieved compared with the arrangement in the horizontal direction.

Further, the ratio of the distance from the first solution outlet 11 to the first sludge outlet 12 to the distance from the upper edge of the sludge hopper is 1:9.

Specifically, by setting the distance between the first solution outlet 11 , the first sludge outlet 12 and the upper edge of the sludge hopper, sludge-water separation can be better achieved.

As an optional embodiment, the electrochemical flocculation device 1 and the electrochemical oxidation device 2 have a plurality of cross-connected cathode plates and anode plates placed parallel to the water flow direction and connected in parallel. The distance between the cathode plate and the anode plate is 5-15mm.

Specifically, the solution inlets of the electrochemical flocculation device 1 and the electrochemical oxidation device 2 are arranged on the upper part, so that the solution flows from top to bottom, and the cathode plate and the anode plate are placed in parallel according to the direction of water flow, thereby improving the solution and the cathode plate and the anode plate. Contact time.

The electrochemical flocculation device 1 and the electrochemical oxidation device 2 may have three anode plates and four cathode plates. The cathode plate and the anode plate are arranged crosswise.

The distance between the cathode plate and the anode plate is preferably 10mm. The closer the distance between the cathode plate and the anode plate, such as 5mm, the cathode passivation rate will be accelerated, and the larger the distance between the plates, such as 15mm, will increase the resistance between the cathode and anode, thus increasing the heat generation. Therefore, 10mm is a more suitable choice, which can reduce the passivation rate of the cathode while maintaining a moderate resistance between the cathode and the anode.

The cathode plate and the anode plate are ensured by good insulation measures that no short circuit or leakage will occur, and they are connected to a constant-voltage constant-current power supply through wires.

Further, the anode plate of the electrochemical flocculation device 1 is made of iron and has a plate structure, and the cathode plate is made of any material such as iron, aluminum, copper or nickel and has a mesh structure.

Specifically, as shown in Figure 1, the anode plate of the electrochemical flocculation device 1, that is, the iron anode plate 13 sacrifices the anode during the reaction process to cause Fe ²⁺ to enter the solution, and Fe ²⁺ combines with ^OH- ions to form adsorbable Macromolecular refractory organic substances, such as ferrous hydroxide or ferric hydroxide of humic acid-like substances and fulvic acid-like substances, the main reaction is as follows:

Fe-2e ^- = Fe ²⁺ ;

Fe ²⁺ +2OH ^- ＝Fe(OH) ₂ ;

Fe(OH) ₂ -e ^- +OH ^- = Fe(OH) ₃ .

The reduction of the cathode plate of the electrochemical flocculation device 1, that is, the first cathode plate 14, promotes the transformation of nitrate nitrogen into ammonia nitrogen, and its main reaction is as follows:

NO ₃ +H ₂ O+2e ⁻ ＝NO ₂ ⁻ +2OH ⁻ ;

NO ₂ ⁻ +6H ₂ O+6e ⁻ =NH ₄ ⁺ +8OH ⁻ .

The first cathode plate 14 may also adopt a plate-like structure. In order to make the water flow pass smoothly, the first cathode plate 14 adopts a mesh electrode. In order to ensure the durability of the anode, the iron anode plate 13 adopts a plate structure.

Iron anode plate 13 adopts cheap iron plate as the anode, and can still achieve high treatment effect under the current density of lower range such as 10-15mA/cm ² , such as the removal rate of 50%-65%, thereby Long-term operation stability can be achieved.

Furthermore, the electrochemical oxidation device 2 has a coated titanium anode plate 24 with a plate structure, and the cathode plate is made of any material such as iron, aluminum, copper or nickel and has a mesh structure.

Specifically, as shown in FIG. 1 , in the electrochemical oxidation device 2 , the coated titanium anode plate 24 has a high oxygen evolution potential and a low chlorine evolution potential. Therefore, after the power is turned on, the chlorine ions in the solution will be quickly oxidized to available chlorine (mainly hypochlorous acid or hypochlorite) at the coated titanium anode plate 24 . The generated available chlorine reacts with ammonia nitrogen and small molecule soluble organic matter in the solution, and finally realizes the removal of ammonia nitrogen and the further removal of COD. The coated titanium anode plate 24 may be a DSA coated titanium anode, where DSA is an abbreviation for Dimensionally Stable Anode, which means dimensionally stable. The main reactions at the coated titanium anode plate 24 are as follows:

Cl ^- -2e ^- + H ₂ O = ClO ^- + 2H ⁺ ;

2NH ₄ ⁺ +3ClO ^- ＝N ₂ +3H ₂ O+2H ⁺ +3Cl ^- ;

ClO ⁻ +COD→CO ₂ +H ₂ O+Cl ⁻ +COP (oxidation product).

The second cathode plate 25 may also adopt a plate-like structure. In order to make the water flow pass smoothly, the second cathode plate 25 adopts a mesh electrode. In order to ensure the durability of the anode, the coated titanium anode plate 24 adopts a plate structure.

The coated titanium anode plate 24 can be made of Ti/IrO ₂ , Ti/Pt, Ti/IrO ₂ -Pt or any one of Ti/RuO ₂ coated titanium materials to make the anode material, so that it can be durable and anti-passivation effect High, it can cope with high-concentration wastewater and run stably for a long time.

In an embodiment, the first cathode 14 and the iron anode 13 are arranged sequentially in the electrochemical flocculation device 1 , specifically, four first cathodes 14 and three iron anode 13 may be included. During operation, the electrochemical flocculation device 1 uses the first DC power supply 15 to be electrically connected to the four first cathodes 14 and the three iron anode plates 13 to provide power to them. After the electrochemical flocculation reaction precipitation is completed, the third pump 6 is turned on to transport the reducing sludge to the available chlorine elimination device 4 . After the reducing sludge is transported, the third pump 6 is turned off, the first pump 3 is turned on, and the electrochemical flocculation aqueous solution containing ammonia nitrogen is transported to the electrochemical oxidation device 2 . In the electrochemical oxidation device 2, a second direct current power source 26 is used to electrically connect the four second cathodes 25 and the three coated titanium anode plates 24 to provide power to them. After the electrochemical oxidation reaction precipitation is completed, the second pump 5 is turned on, and the electrochemical oxidation effluent containing remaining available chlorine is delivered to the available chlorine elimination device for dechlorination. After the dechlorination reaction is completed, the effluent flows out through the dechlorination tank. The whole reaction process adopts the sequential batch operation method. The preferred operating conditions of the electrochemical flocculation device 1 are a current density of 70 mA/cm ² , a reaction time of 30 min, and a precipitation time of 45 min. The preferred operating conditions of the electrochemical oxidation device 2 are 70mA/cm ² , reaction time 60min, and precipitation time 20min. The preferred operating condition of the available chlorine elimination device 4 is 40 minutes (dechlorination reaction+precipitation).

Therefore, the present invention overcomes the problem that the traditional electrochemical oxidation process is difficult to realize the simultaneous removal of COD and TN, and the defect that the by-product available chlorine is difficult to eliminate itself through its own process, strengthens the treatment efficiency, simplifies the operation, and improves the treatment reactor. Practicality of efficient treatment of landfill leachate biochemical effluent.

The second aspect of the invention provides a biochemical effluent treatment method for landfill leachate, realized according to the biochemical effluent treatment reactor for landfill leachate described in the first aspect of the present invention, comprising the following steps:

S1, the macromolecular antioxidant organic matter in the biochemical effluent solution is adsorbed by the flocculation produced by the anode plate of the electrochemical flocculation device 1 to form reducing sludge. S2, the nitrate nitrogen in the biochemical aqueous solution is converted into ammonia nitrogen under the reduction action of the cathode plate of the electrochemical flocculation device 1 . S3, the solution containing ammonia nitrogen in step S2 enters the electrochemical oxidation device 2 capable of generating available chlorine, and ammonia nitrogen reacts with available chlorine to form a first solution without ammonia nitrogen; wherein S1 and S2 are executed simultaneously.

As an optional embodiment, step S4 is also included, the reducing sludge and the first solution are mixed and reacted to eliminate the remaining available chlorine in the first solution, and the reducing sludge contains ferrous hydroxide. Further, precipitation treatment is required in steps S1, S4 and S3.

Specifically, since the reducing sludge contains ferrous hydroxide, it can eliminate available chlorine. As the waste in the electrochemical flocculation reaction process of the electrochemical flocculation device 1, the reduced sludge not only realizes the elimination of excess available chlorine, but also the products of the elimination reaction are mainly Fe ³⁺ -based compounds, thereby reducing the Environmental hazards of reduced sludge itself.

Elimination of available chlorine through step S4 reduces the cost of later elimination of available chlorine.

In the present invention, the macromolecular refractory organic matter (such as humic acid and fulvic acid) contained in the landfill leachate biochemical effluent water is flocculated under the action of Fe ²⁺ flocs formed by sacrificial anodes in the electrochemical flocculation device 1 , forming reducing sludge and separating from the liquid. At the same time, in the electrochemical flocculation device 1, the nitrate nitrogen is reduced to ammonia nitrogen at the cathode, completing its conversion from a high-valence state to a low-valence state. In the electrochemical oxidation device 2, the residual dissolved organic matter in the effluent water of the electrochemical flocculation device 1 undergoes an oxidation reaction with the ammonia nitrogen under the action of the available chlorine generated by the indirect oxidation system, and finally realizes the efficient removal of COD and TN. The excess available chlorine produced in the electrochemical oxidation device 1 undergoes a redox reaction with the collected reducing sludge from the electrochemical flocculation device 1 in the available chlorine elimination device, and the available chlorine is reduced to harmless chlorine ions, In order to achieve the removal of available chlorine.

In summary, the present invention integrates the advantages of electrochemical flocculation and electrochemical oxidation processes, and can eliminate the oxidation by-product available chlorine by itself through the process operation process. Therefore, the purpose of efficiently treating landfill leachate biochemical effluent is achieved, and Elimination of harmful by-products is achieved. In addition, the anode used in the electrochemical flocculation device 1 of the present invention is cheap and durable, and is easy to operate, and the anode material used in the electrochemical oxidation device 2 is not easily lost, thus simplifying the operation and maintenance of the reactor.

Example 1

As shown in Figure 1, a biochemical effluent treatment reactor for landfill leachate includes: an electrochemical flocculation device 1, wherein four first cathode plates 14 and three iron anode plates are arranged crosswise in the electrochemical flocculation device 1 13. During the operation of the electrochemical flocculation device 1 , the first DC power supply 15 is used for power supply. After the electrochemical flocculation reaction and precipitation, the third pump 6 is turned on to transfer the reducing sludge to the available chlorine elimination device 4 . After the transfer of the reducing sludge is completed, the third pump 6 is turned off, the first pump 3 is turned on, and the electrochemical flocculation effluent is transferred to the electrochemical oxidation device 2 . In the electrochemical oxidation device 2, the second DC power supply 26 is used for power supply. After the electrochemical oxidation reaction precipitation is completed, the second pump 5 is turned on to transfer the electrochemical oxidation effluent to the available chlorine elimination device 4 for dechlorination.

Under this condition, the actual landfill leachate biochemical effluent was taken as the experimental object, the current density was set to 70mA/cm ² during the reaction process, the reaction time in the electrochemical flocculation device 1 was 30min, and the reaction time in the electrochemical oxidation device 2 was 120min. The reaction time in the effective chlorine elimination device 4 is 10 minutes, the COD removal rate of the effluent is 94.6%, and the TN removal rate is 96.9%. No available chlorine was detected in the effluent of the available chlorine elimination device 4 .

Example 2

The treatment reactor is set up as in Example 1, and the actual landfill leachate biochemical effluent is used as the experimental object. The current density is set to 50mA/cm ² during the reaction process, the reaction time in the electrochemical flocculation device 1 is 60min, and the reaction time in the electrochemical oxidation device 2 The time is 120min, the reaction time in the available chlorine elimination device ₄ is 10min, and the BOD5/COD value in the solution after the reaction flowed out by the third solution effluent 43 of the available chlorine elimination device 4 rises to 0.35 compared with 0.065 of the influent, indicating that The effluent is suitable for further treatment through microbial reactors. Among them, the COD that can be used by microorganisms is BOD. Here is usually the 5-day biochemical oxygen demand, denoted as BOD ₅ . BOD ₅ /COD is the proportion of BOD ₅ in the total COD. The influent is the biochemical aqueous solution entering the electrochemical flocculation device 1 .

It should first be explained here that "inward" is a direction toward the center of the accommodation space, and "outward" is a direction away from the center of the accommodation space.

In describing the present invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "lateral", "vertical", The orientation or positional relationship indicated by "horizontal", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying the It should not be construed as limiting the invention that a device or element must have a particular orientation, be constructed, and operate in a particular orientation.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

In the present invention, unless otherwise clearly specified and limited, terms such as "installation", "connection", "connection" and "fixation" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection , or integrated; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise specified limit. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In the present invention, unless otherwise clearly specified and limited, the first feature may be in direct contact with the first feature or the first and second feature may be in direct contact with the second feature through an intermediary. touch. Moreover, "above", "above" and "above" the first feature on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "beneath" and "beneath" the first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is less horizontally than the second feature.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (10)

1. a kind of landfill leachate bio-chemical effluent treatment reactor, which is characterized in that including adsorbing macromolecular hardly degraded organic substance It forms reproducibility sludge and the electrochemistry flocculation plant (1), generation effective chlorine and the ammonia nitrogen for so that nitrate nitrogen is converted into ammonia nitrogen is anti- (3) should be pumped with the Electrochemical oxidation device (2) and first of eliminating the ammonia nitrogen,

The electrochemistry flocculation plant (1) opens up the first taphole (11) and the first sludge outlet (12), the electrochemistry oxygen Makeup sets (2) and opens up the first solution inlet port (21)；

The inlet and outlet of first pump (3) corresponds to and first taphole (11) and first solution inlet port respectively (21) it is connected to and in communication with, the reproducibility sludge is flowed out from first sludge outlet (12).

2. treatment reactor according to claim 1, which is characterized in that further include effective chlorine cancellation element (4), the second pump (5), third pump (6), the effective chlorine cancellation element (4) open up the second solution inlet port (41) and sludge import (42), the electricity Chemical oxidation device (2) opens up the second taphole (22), and the inlet and outlet of second pump (5) is corresponding with described the respectively Two tapholes (22) and second solution inlet port (41) are connected to and in communication with；The inlet and outlet difference of the third pump (6) Correspondence is connected to and in communication with first sludge outlet (12) and the sludge import (42).

3. treatment reactor according to claim 2, which is characterized in that the electrochemistry flocculation plant (1) and the electricity Bottom described in chemical oxidation device (2) is using conical sludge bucket, first taphole (11) and second solution Export the outer wall vertical of (22) with the sludge bucket.

4. treatment reactor according to claim 3, which is characterized in that first taphole (11) and institute second are molten Liquid export (22) respectively the distance of the first sludge outlet (12) and second sludge outlet (23) described in respective distances and its away from The distance ratio of the upper edge of the corresponding sludge bucket is 1:9.

5. treatment reactor according to claim 1 or 2, which is characterized in that the electrochemistry flocculation plant (1) and described The cathode plate and anode that multiple intersections that there is Electrochemical oxidation device (2) parallel water (flow) direction to place are laid and are connected in parallel Plate；

The spacing of the cathode plate and anode plate is 5-15mm.

6. treatment reactor according to claim 5, which is characterized in that the anode plate of the electrochemistry flocculation plant (1) It uses iron material matter to make and for platy structure, cathode plate uses iron, aluminium, copper or any material of nickel to make and for reticular structure.

7. treatment reactor according to claim 5, which is characterized in that the Electrochemical oxidation device (2) has plate The coating titanium anode pole plate (24) of structure, cathode plate use iron, aluminium, copper or any material of nickel to make and for reticular structure.

8. a kind of landfill leachate bio-chemical effluent processing method, which is characterized in that according to any one of claims 1 to 7 Landfill leachate bio-chemical effluent treatment reactor is realized, is included the following steps：

S1, the macromolecular hardly degraded organic substance in bio-chemical effluent solution are generated in the anode plate of the electrochemistry flocculation plant (1) Floc sedimentation effect under adsorbed to form reproducibility sludge；

S2, nitrate nitrogen converts under the cathode plate reduction of the electrochemistry flocculation plant (1) in the bio-chemical effluent solution For ammonia nitrogen；

The solution entrance containing ammonia nitrogen can generate the Electrochemical oxidation device (2) of effective chlorine, the ammonia nitrogen in S3, step S2 The first solution to form no ammonia nitrogen is reacted with the effective chlorine；

Wherein S1 and S2 are performed simultaneously.

9. processing method according to claim 8, which is characterized in that further include step 4, the reproducibility sludge and described First solution hybrid reaction contains hydrogen-oxygen to eliminate the remaining effective chlorine in first solution in the reproducibility sludge Change ferrous.

10. processing method according to claim 9, which is characterized in that be both needed to place of settling in described step S1, S4 and S3 Reason.