CN112960819A - Double oxidation-electrochemical oxidation combined process for advanced treatment of landfill leachate - Google Patents

Double oxidation-electrochemical oxidation combined process for advanced treatment of landfill leachate Download PDF

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CN112960819A
CN112960819A CN202110242473.2A CN202110242473A CN112960819A CN 112960819 A CN112960819 A CN 112960819A CN 202110242473 A CN202110242473 A CN 202110242473A CN 112960819 A CN112960819 A CN 112960819A
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oxidation
landfill leachate
treatment
electrochemical oxidation
iron
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韩卫清
张磊
殷许
戴君诚
刘润
袁震
左武杰
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Nanjing Huagong Innovation Environment Research Institute Co ltd
Nanjing University of Science and Technology
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Nanjing Huagong Innovation Environment Research Institute Co ltd
Nanjing University of Science and Technology
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    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
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    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
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    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/465—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electroflotation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
    • C02F1/4672—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electrooxydation
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    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F1/00—Treatment of water, waste water, or sewage
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    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/722—Oxidation by peroxides
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    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/46104—Devices therefor; Their operating or servicing
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    • C02F2101/16—Nitrogen compounds, e.g. ammonia
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    • C02F2101/38—Organic compounds containing nitrogen
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    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/06—Contaminated groundwater or leachate
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    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/08—Chemical Oxygen Demand [COD]; Biological Oxygen Demand [BOD]
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    • C02F2209/14—NH3-N
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    • C02F2209/16—Total nitrogen (tkN-N)

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Abstract

The invention belongs to the technical field of treatment of landfill leachate, and discloses a double oxidation-electrochemical oxidation combined process for advanced treatment of landfill leachate, which comprises the following steps: a) electro-catalytic Fenton treatment: taking a porous composite iron electrode as an anode and stainless steel as a cathode, and adding Fe in a dissolved iron form2+Slowly adding hydrogen peroxide after iron dissolution; b) after the iron dissolution is finished, carrying out electrocatalytic oxidation reaction, and carrying out repeated cycle treatment on the electrocatalytic oxidation reaction and the electrocatalytic Fenton; c) adjusting the effluent of the electrocatalytic oxidation to be alkaline, precipitating iron mud and removing the iron mudTotal phosphorus; d) carrying out electrochemical oxidation treatment: adding a certain amount of sodium chloride, and removing ammonia nitrogen in the percolate by utilizing a tubular membrane electrode chlorine evolution reaction. On the basis of an electrocatalytic Fenton-electrochemical oxidation double oxidation process, the method provided by the invention can be used for continuously oxidizing low-molecular organic acid by adding electrochemical oxidation, realizing degradation of ammonia nitrogen and total nitrogen and realizing deep treatment of the landfill leachate.

Description

Double oxidation-electrochemical oxidation combined process for advanced treatment of landfill leachate
Technical Field
The invention belongs to the technical field of landfill leachate treatment processes, and relates to a combined process for advanced treatment of landfill leachate through double oxidation and electrochemical oxidation.
Background
Landfill leachate is a complex mixture containing dissolved organic compounds (DOM), inorganic compounds, heavy metals, pesticides, medicine residues and the like, which causes great harm to the environment, wherein the contents of aromatic compounds, chlorinated aliphatic compounds, fatty acids, phenolic compounds, polycyclic aromatic hydrocarbons, polychlorinated biphenyl, even perfluorinated compounds (perfluorinated compounds) and the like are high, the organic compounds are stable in chemical property, difficult to degrade by microorganisms, large in Environmental harm, especially in landfill sites with high burying age, and the B/C of the organic compounds is less than 0.3, and the traditional biochemical method is difficult to effectively treat (Fernandes A et al. review on the electrochemical process for the treatment of saline and filtered raw materials: Press and future [ J ]. Applied B Environmental,2015, 176-. In addition to complex organic matters and poor biodegradability, high ammonia nitrogen is a difficult point for landfill leachate treatment, and data show that for landfill sites with the landfill age of more than 10 years, the ammonia nitrogen content can reach as high as 4000mg/L, so that the denitrification of the landfill leachate is difficult, and the situation of excessive total nitrogen often occurs in the operation process (Du Yi et al, water supply and drainage in China, 2015,31(22):33-36.) is an urgent problem to be solved for landfill leachate treatment. At present, the treatment method of landfill leachate mainly comprises the combined process of materialization (pretreatment), biochemistry (including anaerobic and aerobic), materialization (deep treatment) to achieve standard discharge, the main effect of the biochemical treatment stage is to remove biochemical organic matters and ammonia nitrogen in the leachate, and the A/O, A/A/O, MBR process and the like are mainly adopted (Farah, Naz, Ahmed, et al.treatment of land filtration membrane using membranes biology: A review [ J ] desalinization, 2012,287: 41-54.); the advanced treatment further removes organic matters and total nitrogen in the leachate, the standard discharge of the leachate is ensured, the effective interception and separation of most pollutants can be realized by treating the landfill leachate by a membrane filtration method, the effluent quality is stable, the process is the mainstream advanced treatment process of the landfill leachate treatment at present, but membrane pores are easy to block, a large amount of concentrated solution can be generated, secondary pollution is formed, and therefore, the development of the stable and effective advanced treatment method for the landfill leachate has very important practical significance.
Based on the defects of the prior art, a high-efficiency advanced treatment method for landfill leachate is needed to be invented.
Disclosure of Invention
1. Solves the technical problem
Aiming at the characteristics of high COD, high ammonia nitrogen, high total phosphorus, high salinity and the like of the landfill leachate, the prior method ensures that the COD, the ammonia nitrogen, the total nitrogen and the total phosphorus are synchronously and deeply removed, a biological method is utilized to treat imbalance of C/N ratio, and the high salinity can inactivate microorganisms. The invention adopts the combined process of double oxidation and electrochemical oxidation for synergistic treatment, and does not adopt a biological treatment mode, thereby not only avoiding the problem of microorganism inactivation caused by the biological treatment method, but also realizing the high-efficiency synchronous removal of COD, ammonia nitrogen and total phosphorus.
2. Technical scheme
In order to solve the problems, the technical scheme adopted by the invention is as follows:
the invention provides a double oxidation-electrochemical oxidation combined process for advanced treatment of landfill leachate, which comprises the following steps:
a) electro-catalytic Fenton treatment: taking an iron electrode as an anode and stainless steel as a cathode, and adding Fe in a dissolved iron form2+Slowly adding hydrogen peroxide after iron dissolution;
b) after the iron dissolution is finished, carrying out electrocatalytic oxidation reaction, and carrying out repeated circulating treatment on the electrocatalytic oxidation reaction in the step b) and the electrocatalytic Fenton in the step a);
c) adjusting the effluent after the cyclic treatment in the step a) and the step b) to be alkaline so as to precipitate iron mud, wherein the total phosphorus can be removed by the iron mud precipitation;
d) carrying out electrochemical oxidation treatment on the effluent obtained in the step c): adding a certain amount of sodium chloride, and removing ammonia nitrogen in the percolate by utilizing a tubular membrane electrode chlorine evolution reaction to obtain final effluent.
Preferably, the electrochemical oxidation treatment devices adopted in the step b) and the step d) both use a tubular membrane electrode as an anode and a titanium tube as a cathode.
In a preferred embodiment, the tubular membrane electrode in step b) is Ti/PbO2Or Ti/SnO2-an Sb coated electrode; and/or the current density of the electrocatalytic oxidation reaction is 5-20mA/cm2The retention time is 4-18 h.
Preferably, in step d), the tubular membrane electrode is Ti/RuO2Coating with current density of 10-25mA/cm2The adding amount of the sodium chloride is 5-20 g/L.
The preferable scheme also comprises a pretreatment reaction: after the landfill leachate is flocculated and precipitated, taking supernatant to adjust the pH value to acidity.
In the preferable scheme, in the step a), the pH value of the landfill leachate is adjusted to 3-4, and the iron dissolving time is 4-12 h.
Preferred embodiment, H in each liter of landfill leachate2O2(30% wt) the mass ratio of the addition amount to the COD is (1-2.5): 1; fe2+Amount of addition and H2O2The molar ratio of the added amount is 1 (8-20).
Preferably, the iron electrode in the step a) is a porous composite iron electrode, and the porous composite iron electrode is prepared by mixing raw iron powder (45% by mass) and cooked iron powder (55% by mass).
In the preferable scheme, in the step c), the pH value of the effluent is adjusted to 9-14, and standing and precipitation are carried out without PAM and PAC auxiliary precipitation.
In a preferred scheme, the technical scheme of the invention is specifically divided into 4 steps, and the process flow is as follows:
step 1: after the landfill leachate is subjected to flocculation precipitation, taking supernate to adjust the pH value to acidity, then performing electro-catalytic Fenton treatment, taking a porous composite iron electrode as an anode and stainless steel as a cathode, and adding Fe in a dissolved iron form2+Meanwhile, the dissolved iron can generate an electric floating effect to remove suspended matters in the leachate, and hydrogen peroxide is slowly added after the iron is dissolved;
step 2: after the electro-catalytic Fenton iron dissolution is finished, starting an electrochemical oxidation device, wherein a tubular membrane electrode is used as an anode of the device, a titanium tube is used as a cathode of the device, and the step 1 is performed in a synchronous cycle manner, so that the synergistic effect of electro-catalytic Fenton and electrochemical oxidation is realized, the oxidation effect is enhanced, and COD is removed efficiently;
and step 3: adjusting the effluent water after the circulating treatment in the steps 1 and 2 to be alkaline by using liquid caustic soda, precipitating iron mud, and simultaneously removing total phosphorus in the leachate;
and 4, step 4: and (3) performing electrochemical oxidation treatment on the effluent obtained in the step (3), adding a certain amount of sodium chloride into the landfill leachate, and removing COD (chemical oxygen demand) and ammonia nitrogen in the leachate by using a tubular membrane electrode chlorine precipitation reaction to obtain final effluent.
The invention is beneficial to the process to realize effective deep removal of refractory organic pollutants, ammonia nitrogen, total nitrogen and total phosphorus in the landfill leachate by constructing a double oxidation-electrochemical oxidation combined process route. In addition, by utilizing the characteristics of high salinity and strong conductivity of the landfill leachate, the high-efficiency degradation of organic matters is realized under the condition of lower power consumption, on the basis of a single electrocatalytic Fenton-electrochemical oxidation double-oxidation process, the electrochemical oxidation is increased, the low-molecular organic acid can be continuously oxidized, the degradation of ammonia nitrogen and total nitrogen can be realized, and the advanced treatment of the landfill leachate is realized. The concrete embodiment is as follows: the 'electrocatalytic Fenton-electrochemical oxidation' double oxidation process can efficiently remove COD (chemical oxygen demand) of wastewater, but in the process of gradually mineralizing organic matters, low-molecular organic acid can be gradually accumulated, the energy barrier of the low-molecular organic acid is higher, the oxidation capacity of hydroxyl radical generated by double oxidation is limited, and the removal of the COD can be further limited.
The ability of removing ammonia nitrogen and total nitrogen by hydroxyl radicals generated by the electrocatalytic Fenton-electrochemical oxidation double oxidation process is limited, but the double oxidation and electrochemical oxidation combined process can convert most organic nitrogen into ammonia nitrogen in the double oxidation stage, and in the electrochemical oxidation stage, after sodium chloride is added, a breakpoint chlorination reaction can be formed by using available chlorine generated by an anode, so that the high degree removal of the ammonia nitrogen and the total nitrogen is realized. The breakpoint chlorination reaction is as follows:
electrochemical anode: cl--e→Cl2
Cl2+2OH-→ClO-+Cl-+H2O
Figure BDA0002962691970000031
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) the double oxidation-electrochemical oxidation combined process for deeply treating the landfill leachate combines electro-catalytic Fenton and electrochemical oxidation by utilizing the characteristics of high salinity and strong conductivity of the landfill leachate, realizes effective removal of refractory organic pollutants in the landfill leachate, solves the problems of low efficiency and poor pollutant degradation capability of a single Fenton oxidation technology and an electrochemical oxidation technology, can realize efficient degradation of organic matters under lower electric energy consumption, and simultaneously realizes effective removal of total phosphorus through excessive iron ion precipitation. In addition, by adding sodium chloride, ammonia nitrogen and low molecular weight organic acid in the leachate are removed by using the chlorine precipitation effect of the anode, so that efficient and synchronous removal of COD, total phosphorus, ammonia nitrogen and the like is realized.
(2) The invention combines double oxidation and a single electrochemical oxidation process, removes COD by using the oxidation effect of double oxidation on organic matters, simultaneously converts organic nitrogen into ammonia nitrogen, converts organic phosphorus into inorganic phosphorus, then removes the inorganic phosphorus by forming a precipitate with iron to realize the removal of total phosphorus (the removal rate of the total phosphorus is more than 90%), then removes the ammonia nitrogen (the removal rate of the ammonia nitrogen is more than 90%) and the total nitrogen (the removal rate of the total nitrogen is more than 90%) by using the chlorine evolution reaction of electrochemical oxidation, continuously oxidizes low molecular organic acids accumulated by double oxidation, and further enhances the removal rate of the COD (the removal rate of the COD is more than 95%).
Drawings
FIG. 1 is a schematic diagram of a dual oxidation-electrochemical oxidation combined process of the present invention.
Detailed Description
The present invention is further described below by way of specific examples and figures to provide a more complete understanding of the invention to those skilled in the art, but not to limit the invention in any way.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs; as used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
As used herein, the term "about" is used to provide the flexibility and inaccuracy associated with a given term, measure or value. The degree of flexibility for a particular variable can be readily determined by one skilled in the art.
Concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a numerical range of about 1 to about 4.5 should be interpreted to include not only the explicitly recited limit values of 1 to about 4.5, but also include individual numbers (such as 2, 3, 4) and sub-ranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges reciting only one numerical value, such as "less than about 4.5," which should be construed to include all of the aforementioned values and ranges. Moreover, such an interpretation should apply regardless of the breadth of the range or feature being described.
Any steps recited in any method or process claims may be executed in any order and are not limited to the order presented in the claims.
As used herein, landfill leachate is taken from a domestic landfill site in Chongqing, about 10 years old, and belongs to middle and late stage landfill leachate.
Example 1
The method adopts an electro-catalytic Fenton-electrochemical oxidation process to remove COD, total phosphorus and ammonia nitrogen in the landfill leachate, and comprises the following specific steps:
step 1, taking 5L of landfill leachate, pretreating a water sample by adopting flocculation precipitation, taking supernate, adjusting the pH value to 3.0-4.0 by using sulfuric acid, taking a porous composite iron electrode as an anode (10cm multiplied by 20cm), taking stainless steel as a cathode (10cm multiplied by 20cm), dissolving iron for 4 hours, carrying out current 1.8A and voltage 1.92V, slowly adding 92.8g (30% wt) of hydrogen peroxide after finishing adding, wherein H is added into each liter of landfill leachate2O2The mass ratio of the adding amount to the COD is 1:1, Fe produced by said iron dissolution2+Amount of addition and H2O2The molar ratio of the adding amount is 1:8,
step 2, after the iron dissolution in the step 1 is finished, starting an electrochemical oxidation process, and selecting Ti/PbO2Anode with a current density of 10mA/cm2(electrode area 100 cm)2) The voltage is 2.6V, the wastewater and the electro-catalysis Fenton are synchronously circulated and stay for 18 h;
and 3, after the reaction is finished, adjusting the pH to 9-11 by using caustic soda flakes, standing for 1h, and taking the supernatant for the next reaction.
Step 4, adding 50g of sodium chloride to ensure that the concentration of the sodium chloride in the water body reaches 10g/L, and adopting a tubular Ti/RuO2Performing chlorine evolution reaction at a current density of 15mA/cm2And reacting for 8 hours. The degradation effect of the treatment of example 1 is shown in Table 1.
Comparative example 1:
firstly carrying out electrochemical oxidation, and then carrying out a double oxidation process to remove COD, total phosphorus and ammonia nitrogen in the landfill leachate, and specifically comprising the following steps:
step 1, taking 5L of landfill leachate with the same water quality as in example 1, pretreating a water sample by using flocculation precipitation, taking supernate, adjusting the pH to 10-11 by using caustic soda flakes, adding 50g of sodium chloride to enable the concentration of the sodium chloride in a water body to reach 10g/L, and adopting a tubular Ti/RuO2Performing chlorine evolution reaction at a current density of 15mA/cm2And reacting for 8 hours.
And 2, regulating the pH value of the effluent obtained in the previous step to 3.0-4.0 by using sulfuric acid, dissolving iron for 2.5 hours by using a porous composite iron electrode as an anode (10cm multiplied by 20cm) and stainless steel as a cathode (10cm multiplied by 20cm), wherein the current is 1.8A, the voltage is 1.92V, and slowly adding 92.8g (30% by weight) of hydrogen peroxide after finishing. In each liter of landfill leachate, H2O2The mass ratio of the adding amount to the COD is 1:1, Fe produced by said iron dissolution2+Amount of addition and H2O2The molar ratio of the added amount is 1: 8.
Step 3, after the iron dissolution in the step 1 is finished, starting an electrochemical oxidation process, and selecting Ti/PbO2Anode with a current density of 10mA/cm2(electrode area 100 cm)2) The voltage is 2.4V, the wastewater and the electro-catalysis Fenton are synchronously circulated and stay for 18 h;
and 4, after the reaction is finished, adjusting the pH to 9-14 by using caustic soda flakes, standing for 1h, and taking the supernatant for measurement. Comparative example 1 a list of the effect of treatment degradation is shown in table 2.
Table 1 summary of degradation effects of example 1
COD(mg/L) Ammonia nitrogen (mg/L) Total nitrogen (mg/L) Total phosphorus (mg/L)
Inflow water 5568 3300 3670 173
Double-oxidation effluent 756 3528 3652 8.1
Electrochemical oxidation effluent 312 253 294 8.0
TABLE 2 summary of the degradation effects of comparative example 1
COD(mg/L) Ammonia nitrogen (mg/L) Total nitrogen (mg/L) Total phosphorus (mg/L)
Inflow water 5568 3300 3670 173
Electrochemical oxidation effluent 3712 411 725 172
Double-oxidation effluent 812 652 721 7.2
According to the results, the method utilizes the double oxidation and the electrochemical oxidation to generate a synergistic effect, the sodium chloride is added in the electrochemical oxidation, the ammonia nitrogen and the low-molecular organic acid in the leachate can be removed by utilizing the chlorine separation effect of the anode, the effects of synchronously and efficiently removing COD, ammonia nitrogen, total nitrogen and total phosphorus are realized, the electrochemical oxidation is directly adopted, and the removal rate of each pollutant is relatively low by carrying out the double oxidation.
Comparative example 2
This embodiment is basically the same as embodiment 1 except that: step 4 no sodium chloride was added. The results are as follows:
table 3 summary of degradation effects of example 3
COD(mg/L) Ammonia nitrogen (mg/L) Total nitrogen (mg/L) Total phosphorus (mg/L)
Inflow water 5568 3300 3670 173
Double-oxidation effluent 756 3528 3652 8.1
Electrochemical oxidation effluent 613 3014 3140 7.5
Example 2
The method adopts an electro-catalytic Fenton-electrochemical oxidation process to remove COD, total phosphorus and ammonia nitrogen in the landfill leachate, and comprises the following specific steps: .
Step 1, taking 5L of landfill leachate, pretreating a water sample by adopting flocculation precipitation, taking supernate, adjusting the pH value to 3.0-4.0 by using sulfuric acid, taking a porous composite iron electrode as an anode (10cm multiplied by 20cm), taking stainless steel as a cathode (10cm multiplied by 20cm), dissolving iron for 5 hours, carrying out current 1.0A and voltage 1.17V, and slowly adding 111.4g (30% wt) of hydrogen peroxide after finishing. In each liter of landfill leachate, H2O2The mass ratio of the adding amount to the COD is 1.5: 1, Fe produced by said iron dissolution2+Amount of addition and H2O2The molar ratio of the added amount is 1: 12.
Step 2, after the iron dissolution in the step 1 is finished, starting an electrochemical oxidation process, and selecting Ti/SnO2-Sb Anode set Current Density 5mA/cm2(electrode area 100 cm)2) The voltage is 3.4V, the wastewater and the electro-catalysis Fenton are synchronously circulated and stay for 12 hours;
and 3, after the reaction is finished, adjusting the pH to 9-14 by using caustic soda flakes, standing for 1h, measuring that the COD is 672mg/L, the removal rate reaches 87.9 percent, the total phosphorus concentration is 5.4mg/L, the removal rate reaches 96.8 percent, and taking supernatant for next reaction.
Step 4, adjusting the pH to be more than 12 by using caustic soda flakes, adding 25g of sodium chloride to ensure that the concentration of the sodium chloride in the water body reaches 5g/L, and adopting a tubular Ti/RuO2Performing chlorine evolution reaction at a current density of 20mA/cm2The degradation effect of example 2 at 8h is shown in Table 4.
Table 4 table of degradation effect of example 2
COD(mg/L) Ammonia nitrogen (mg/L) Total nitrogen (mg/L) Total phosphorus (mg/L)
Inflow water 6087 3415 3884 206
Double-oxidation effluent 811 3711 3814 11.5
Electrochemical oxidation effluent 356 411 488 11.2
Example 3
And removing COD, total phosphorus and ammonia nitrogen in the landfill leachate by adopting an electro-catalytic Fenton-electrochemical oxidation process.
Step 1, taking 5L of landfill leachate, pretreating a water sample by adopting flocculation precipitation, taking supernate, adjusting the pH value to 3.0-4.0 by using sulfuric acid, taking a porous composite iron electrode as an anode (10cm multiplied by 20cm), taking stainless steel as a cathode (10cm multiplied by 20cm), dissolving iron for 12 hours, carrying out current 2A and voltage 2.16V, slowly adding 139.2g (30% wt) of hydrogen peroxide into each liter of landfill leachate, and adding H into each liter of landfill leachate2O2The mass ratio of the adding amount to the COD is 2.5: 1, Fe produced by said iron dissolution2+Amount of addition and H2O2The molar ratio of the adding amount is 1:20,
step 2, after the iron dissolution in the step 1 is finished, starting an electrochemical oxidation process, and selecting Ti/PbO2Anode with a set current density of 20mA/cm2(electrode area 100 cm)2) The voltage is 3.4V, the wastewater and the electro-catalysis Fenton are synchronously circulated and stay for 4 hours;
and 3, after the reaction is finished, adjusting the pH to 9-14 by using caustic soda flakes, standing for 1h, measuring that the COD is 396mg/L, the removal rate reaches 92.8%, the total phosphorus concentration is 6.6mg/L, the removal rate reaches 96.2%, and taking the supernatant for the next reaction.
Step 4, adding 100g of sodium chloride to ensure that the concentration of the sodium chloride in the water body reaches 20g/L, and adopting a tubular Ti/RuO2Performing chlorine evolution reaction at a current density of 25mA/cm2And reacting for 6 hours, and measuring that the COD is 122mg/L, the removal rate reaches 69.1 percent, and the ammonia nitrogen concentration is 276mg/L and the removal rate is 91.6 percent. The degradation effect of example 3 is shown in Table 5.
Table 5 table of degradation effect of example 3
Figure BDA0002962691970000071

Claims (9)

1. A double oxidation-electrochemical oxidation combined process for deeply treating landfill leachate is characterized by comprising the following steps of:
a) electro-catalytic Fenton treatment: taking an iron electrode as an anode and stainless steel as a cathode, and adding Fe in a dissolved iron form2+Slowly adding hydrogen peroxide after iron dissolution;
b) after the iron dissolution is finished, carrying out electrocatalytic oxidation reaction, and carrying out repeated circulating treatment on the electrocatalytic oxidation reaction in the step b) and the electrocatalytic Fenton in the step a);
c) adjusting the effluent after the cyclic treatment of a) and b) to be alkaline so as to precipitate iron mud;
d) carrying out electrochemical oxidation treatment on the effluent treated in the step c): adding a certain amount of sodium chloride, and removing ammonia nitrogen in the percolate by utilizing a tubular membrane electrode chlorine evolution reaction.
2. The dual oxidation-electrochemical oxidation combined process for advanced landfill leachate according to claim 1, wherein the electrochemical oxidation treatment device used in step b) and step d) uses tubular membrane electrode as anode and titanium tube as cathode.
3. The combined double oxidation-electrochemical oxidation process for the advanced treatment of landfill leachate according to claim 1 or 2, wherein the tubular membrane electrode in step b) is Ti/PbO2Or Ti/SnO2-an Sb coated electrode; and/or the current density of the electrocatalytic oxidation reaction is 5-20mA/cm2The retention time is 4-16 h.
4. The combined double oxidation-electrochemical oxidation process for the advanced treatment of landfill leachate of claim 3, wherein in step d), the tubular membrane electrode is Ti/RuO2Coating with current density of 10-25mA/cm2。
5. The combined double oxidation-electrochemical oxidation process for the advanced treatment of landfill leachate of claim 4, wherein the sodium chloride is added in an amount of 5-20 g/L.
6. The combined double oxidation-electrochemical oxidation process for the advanced treatment of landfill leachate of claim 5, further comprising a pretreatment reaction: after the landfill leachate is flocculated and precipitated, taking supernatant to adjust the pH value to acidity.
7. The dual oxidation-electrochemical oxidation combined process for advanced treatment of landfill leachate according to claim 6, wherein in step a), the landfill leachate pH is adjusted to 3-4, and the iron dissolution time is 4-12 h.
8. The combined dual oxidation-electrochemical oxidation process for the advanced treatment of landfill leachate of claim 7, wherein, the combined process comprises the steps of, per liter of landfill leachateIn the percolate, H2O2The mass ratio of the adding amount to the COD is (1-2.5): 1; fe2+Amount of addition and H2O2The molar ratio of the added amount is 1 (8-20).
9. The dual oxidation-electrochemical oxidation combined process for advanced treatment of landfill leachate of claim 8, wherein in step c), the pH is adjusted to 9-14, and the solution is left to stand for precipitation.
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