A method and device for efficiently degrading landfill leachate by chemical method

Abstract

Provided is a method for efficiently degrading leachate by chemical method, comprising the following steps: (1) oxidizing the leachate with oxidizing gas in a gas-liquid mixing reaction tank (4) to obtain oxidized reaction liquid B; (2) performing Fenton oxidation reaction on the oxidized reaction liquid B under acidic condition to obtain oxidized reaction liquid C; (3) adding alkaline substance to the oxidized reaction liquid C to make the solution react to produce precipitate and obtain solid-liquid mixture D; (4) performing solid-liquid separation on the solid-liquid mixture D to obtain filter residue E and filtrate E, wherein the filtrate E is the solution after process treatment. The method can greatly reduce the COD value and metal ion content in the leachate, thereby achieving the purpose of environmental protection. Also disclosed is an apparatus for treating leachate by using the above method.

Description

A method and equipment for treating landfill leachate with high efficiency chemical degradation Technical Field

[0001] The present invention belongs to the technical field of environmental protection treatment industry, and specifically relates to a method and equipment for treating garbage leachate with high efficiency degradation by chemical method. Background Art

[0002] With the economic development of society, people's living standards are constantly improving. The large amount of discarded domestic garbage is used to make landfills, which are constantly occupying and expanding. It has become urgent to solve the pollution problem of garbage leachate.

[0003] Landfill leachate is a highly concentrated organic wastewater formed after passing through layers of garbage and overburden. It typically originates from four sources: moisture from the garbage itself, moisture from reactions, moisture from groundwater seepage, and moisture from rain and snow. Leachate contains a large amount of organic matter, including carbohydrates, fats, proteins, and cellulose, resulting in a highly complex composition. Furthermore, landfills are hotbeds for microbial growth, and their wastewater harbors numerous pathogens. Therefore, while ensuring environmentally friendly treatment of leachate, it is also crucial to ensure pathogen elimination and prevent the spread of infectious diseases. Consequently, leachate treatment presents numerous challenges.

[0004] Since the cost of using existing waste liquid treatment technology to completely treat landfill leachate is too high and the space required is too large, landfill leachate is generally not completely treated. Currently, there are three main types of landfill leachate treatment processes:

[0005] (1) Biological treatment + membrane treatment process;

[0006] (2) Full membrane adsorption filtration treatment process;

[0007] (3) Low-consumption evaporation + ion exchange treatment process.

[0008] Of the three typical processes mentioned above, the first and second types are generally considered to have higher treatment efficiency and relatively low capital investment compared to existing technologies, achieving economically favorable system water production rates of approximately 60% or more, and are therefore more commonly used. However, the third type of process requires higher energy consumption, and the ion exchange resins used require frequent handling and replacement, resulting in higher operating costs.

[0009] The first and second types of processes are specifically to process the raw leachate in the landfill through a biochemical pool or a regulating pool and then directly send it into a high-pressure pump. The high-pressure pump will press the organic waste liquid into a first-level DTRO reverse osmosis membrane device for treatment to obtain a first-level concentrated liquid and a first-level clear liquid. The obtained first-level clear liquid is further pressed into a second-level DTRO reverse osmosis membrane device from another high-pressure pump for treatment. After being treated by two-level reverse osmosis membranes, a second-level clear liquid and a second-level concentrated liquid are obtained. Among them, the second-level clear liquid meets the standards and enters the urban sewage network side by side. At present, the COD value acceptance index of the urban sewage network for organic waste liquid is generally no more than 1000ppm. The second-level concentrated liquid is led back to the inlet of the landfill leachate raw liquid treatment equipment for re-treatment, while the first-level concentrated liquid is re-injected into the landfill area for centralized treatment. Therefore, although the treatment methods of the first and second types of processes are simple to operate, highly efficient, and require relatively little capital investment,

[0010] (1) Since the concentrated leachate produced is often re-injected into the landfill, this method does not significantly reduce the total waste volume in the landfill, resulting in the continued accumulation of pollutants in the landfill. Moreover, over time, the biodegradability of the leachate gradually deteriorates, leading to membrane blockage, an increase in the proportion of concentrated liquid, and high pollutant concentrations in the clear liquid, making it difficult to treat and meet standards, thus affecting the effective and stable operation of the leachate raw liquid treatment system.

[0011] ⑵ The price of reverse osmosis equipment generally starts at several million RMB, and consumables need to be frequently replaced. There is still much room for improvement in cost savings;

[0012] ⑶ When metal ions exist in the landfill leachate, the high concentration of local metal compounds may cause precipitation during the reverse osmosis operation, leading to membrane blockage and shortening the membrane service life.

[0013] Therefore, it is necessary to improve this treatment process. After the improvement, in addition to strengthening the safety and occupational health management during the environmental protection treatment process, it is also necessary to achieve the goal of not re-injecting the landfill area after the treatment of the garbage leachate.

[0014] Summary of the Invention

[0015] The first object of the present invention is to provide a method for treating landfill leachate by chemical degradation with high efficiency, wherein the landfill leachate is treated by chemical degradation to significantly reduce the COD value and metal ion content in the landfill leachate, thereby achieving the purpose of environmental protection treatment.

[0016] The second invention aims to provide a device for treating landfill leachate by chemically and efficiently degrading it.

[0017] The first object of the present invention is achieved through the following solutions.

[0018] A method for treating landfill leachate by chemically efficiently degrading the landfill leachate comprises the following steps:

[0019] (1) subjecting the landfill leachate to an oxidation reaction with an oxidizing gas in a gas-liquid mixing reactor to obtain an oxidation reaction liquid B;

[0020] (2) subjecting the oxidation reaction liquid B to a Fenton oxidation reaction under acidic conditions to obtain an oxidation reaction liquid C;

[0021] (3) adding an alkaline substance to the oxidation reaction solution C to cause a reaction in the solution to produce a precipitate and obtain a solid-liquid mixture D;

[0022] (4) The solid-liquid mixture D is subjected to solid-liquid separation to obtain a filter residue E and a filtrate E, wherein the filtrate E is a solution processed according to the process.

[0023] For pollutants in landfill leachate, different reactants, or even the same reactants under different reaction conditions, will produce different chemical reactions, thereby producing different products. Therefore, the order of steps in the landfill leachate treatment reaction is crucial. After multiple experimental verifications, the inventors found that first using an oxidizing gas to oxidize the landfill leachate, and then using the Fenton oxidation reaction to treat the oxidation reaction liquid B obtained in the previous step, can help achieve the treatment of organic matter content in all landfill leachate to meet standards, so that it can be subsequently discharged into the urban sewage network, and may even achieve the water quality for direct discharge. The oxidation reaction liquid B contains the product of step (1) and substances that did not participate in the reaction in the previous step.

[0024] In step (1), the landfill leachate is mixed with an oxidizing gas to undergo a gas-liquid reaction. The oxidizing gas is chlorine and / or ozone. Ozone is preferably used because it has a stronger oxidizing property than chlorine in the oxidation reaction of the landfill leachate.

[0025] Preferably, the ozone used is ozone generated by an ozone generator. The ozone generator is a device that converts oxygen into ozone through the action of a high-frequency, high-voltage electric field. The oxygen used is specifically commercial oxygen and / or oxygen produced by ordinary chemical reactions and / or oxygen produced by electrolysis in an electrolytic cell. The oxygen from these different sources can be used alone or in combination.

[0026] Preferably, the chlorine used is commercial chlorine and / or chlorine produced by common chemical reactions and / or chlorine produced by electrolysis in an electrolytic cell. Chlorine from different sources may be used alone or as a mixture of more than one.

[0027] The landfill leachate in step (1) can react with the oxidizing gas under acidic, alkaline or neutral conditions, wherein the oxidation reaction of carbohydrates in the landfill leachate is mainly carried out, and may be accompanied by the oxidation reaction of other pollutants. The products remaining in the oxidation reaction liquid B after the oxidation of other organic pollutants will continue to participate in the reaction in the subsequent treatment steps. The chemical reaction principle of the reaction of carbohydrates in the landfill leachate with the oxidizing gases ozone and chlorine is as follows: × (H2O) y +O3→CO2+H2O C × (H2O) y +Cl2→CO2+H2O+HCl

[0028] If the landfill leachate is reacted with an oxidizing gas under alkaline conditions but the leachate itself does not reach the desired alkaline conditions, an alkaline pH adjuster must be added to the leachate to convert the reaction solution into an alkaline solution before reacting with the oxidizing gas. The alkaline pH adjuster can be selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

[0029] When metal ions other than potassium and sodium are present in the landfill leachate, an alkaline pH adjuster is added to the landfill leachate or oxidation reaction solution B in step (1) to convert the solution into an alkaline state, so that part or all of the metal ions contained in the solution can be converted into carbonate and / or hydroxide precipitates and / or phosphate precipitates, thereby achieving chemical softening treatment of the landfill leachate or oxidation reaction solution B after solid-liquid separation.

[0030] In step (2), the oxidation reaction liquid B is subjected to a Fenton oxidation reaction under acidic conditions. The Fenton oxidation reaction is a process in which at least one of ferrous hydroxide, ferrous sulfate, and ferrous chloride reacts with hydrogen peroxide in the oxidation reaction liquid B to generate hydroxyl radicals to oxidatively degrade organic matter. When the oxidation reaction liquid B is an alkaline solution, an acidic pH adjuster is added to adjust it to acidic according to process requirements before the Fenton oxidation reaction is carried out. The acidic pH adjuster is hydrochloric acid and / or sulfuric acid. The ferrous compound participating in the Fenton treatment can be an externally added ferrous compound or a ferrous compound formed by chemically reducing the trivalent iron compound in the solution.

[0031] In step (3), an alkaline substance is added to the oxidation reaction solution C to form an iron hydroxide precipitate in the solution. The precipitated colloid binds a considerable portion of the organic pollutants in the solution to form a co-precipitation, thereby removing some of the organic impurities in the treated liquid. When the oxidation reaction solution C contains metal ions other than potassium and sodium, some or all of the metal ions in the solution can also be converted into carbonate and / or hydroxide precipitates and / or phosphate precipitates. The alkaline substance is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

[0032] In step (4), the main component of the filter residue E is iron hydroxide, which should be treated as hazardous waste because it contains organic pollutants. To save production costs and achieve environmentally friendly recycling, the filter residue E can be treated at high temperature to decompose the organic pollutants and process the iron oxide raw material for reuse. The filtrate E is the solution processed according to the process of the present invention.

[0033] The present invention can be improved as follows: before step (1), the landfill leachate is mixed with an acidic substance to undergo an acidification reaction, so that the protein in the landfill leachate is denatured and coagulated into flocs to obtain a solid-liquid mixture.

[0034] In the above-mentioned improvement scheme, the principle of chemical reaction between protein-containing liquid and acidic substance to form insoluble floccules is utilized, and acidic substance is added to the original landfill leachate to make it acidic, so that at least part of the protein therein forms floccules under acidic conditions. After solid-liquid separation, the organic matter content in the landfill leachate can be reduced.

[0035] Preferably, an acidic substance is added to the raw landfill leachate to a pH value of less than or equal to 5.5. More preferably, an acidic substance is added to the raw landfill leachate to a pH value of less than 2. The acidic substance is hydrochloric acid and / or sulfuric acid. More preferably, sulfuric acid is used as the acidic substance to adjust the pH value of the landfill leachate.

[0036] The present invention can be further improved as follows: before step (1), the landfill leachate is mixed with an acidic substance to undergo an acidification reaction, causing the protein in the landfill leachate to denature and coagulate into flocs. The resulting solid-liquid mixture is subjected to solid-liquid separation to obtain acidic filtrate A and filter residue A, and the acidic filtrate A is subjected to steps (1) to (4). The filter residue A obtained after solid-liquid separation is a protein floc, which can be sent to a high-temperature furnace for combustion treatment. The filtrate A is an organic waste liquid and needs to continue to undergo environmental protection treatment in steps (1) to (4) of the present invention.

[0037] The present invention can be further improved by treating the gases emitted during the acidification reaction prior to step (1) above in an environmentally friendly manner. Acid gas is generated during the acidification reaction, particularly when the landfill leachate being treated contains sulfur compounds. Hydrogen sulfide is a colorless, highly toxic gas that can damage the central nervous system and respiratory system upon inhalation. Therefore, the gases emitted during the acidification reaction should be treated in an environmentally friendly manner, specifically by absorbing the tail gas to prevent the spread of the acid gas or its combination with toxic gases.

[0038] The present invention treats the tail gas in step (1) by using water or alkaline solution as the tail gas absorption reaction liquid, passing the tail gas into the absorption reaction liquid, dissolving the tail gas in water or allowing the tail gas to undergo acid-base neutralization reaction with the alkaline solution, and then the acid gas or the acid gas and the toxic gas are digested.

[0039] The present invention can also be further improved as follows: after completing the acidification treatment before step (1), hydrogen peroxide is added to the resulting solid-liquid mixture to kill the pathogens therein, which is beneficial for killing the pathogens as early as possible, avoiding the environment and people in the subsequent process from being harmed by pathogens, so that subsequent operations can comply with occupational health and safety management requirements, and provide a safe working environment for subsequent processes.

[0040] In the present invention, when a precipitate is generated during the reaction process in step (1), a solid-liquid separator can be used to separate the solid impurities therein to better facilitate the treatment effect of subsequent steps. After solid-liquid separation, an oxidation reaction liquid B and a filter residue B are obtained, wherein the main component of the filter residue B is an insoluble metal salt or a precipitated metal hydroxide or an organic precipitate.

[0041] The present invention can also be improved as follows: the cathode tank area of ​​the electrolytic cell provided with an anode tank area and a cathode tank area is used to perform an electrochemical reduction reaction on the liquid to be treated, such as landfill leachate, oxidation reaction liquid or filtrate of the oxidation reaction liquid, so that the liquid to be treated can be effectively degraded regardless of whether it is acidic or alkaline.

[0042] Preferably, an electrolytic cell is used to perform a reduction reaction on the liquid to be treated in at least one of the following situations:

[0043] (i) before step (1);

[0044] (ii) before step (2);

[0045] (iii) after step (2);

[0046] (iv) after step (4);

[0047] Organic waste liquid is subjected to organic degradation treatment by a combined method of electro-oxidation-reduction reaction.

[0048] The present invention can also be improved as follows: at least one oxidation step is added in at least one of the following situations:

[0049] (i) before step (2);

[0050] (ii) after step (2);

[0051] (iii) after step (4);

[0052] The oxidation step is selected from at least one of the following schemes:

[0053] Scheme ① uses oxidizing gas to carry out oxidation reaction in a gas-liquid mixed reactor;

[0054] Scheme ②: Fenton oxidation reaction is carried out under acidic conditions;

[0055] Scheme ③ uses an electrolytic cell provided with an anode tank area and a cathode tank area, and conducts an electrochemical oxidation reaction in the anode tank area.

[0056] Among them, the oxidation step added after step (4) is only selected from the above-mentioned scheme ① or scheme ③.

[0057] If the scheme ② is adopted as the additional oxidation step, after the Fenton oxidation reaction is completed, the operation and treatment of the next step can be directly carried out, or an alkaline substance can be added to the oxidation reaction solution to cause the solution to react to produce a precipitate and perform solid-liquid separation, and then the obtained filtrate can be subjected to the operation and treatment of the next step.

[0058] The present invention uses the anode tank area of ​​the electrolytic cell provided with the anode tank area and the cathode tank area to perform electrochemical oxidation reaction on the reaction liquid, while the cathode tank area of ​​the electrolytic cell can be used to perform electrochemical reduction reaction on the liquid to be treated that needs reduction reaction as described above.

[0059] The present invention can be further improved as follows: before and / or after the at least one additional oxidation step, the cathode tank area in the electrolytic cell provided with an anode tank area and a cathode tank area is used to perform an electrochemical reduction reaction on the reaction liquid. The reaction liquid can be treated by a combination of repeated oxidation-reduction reactions, that is, more than one oxidation step and at least one electrolytic reduction reaction step are performed alternately, so that the organic matter in the waste liquid is rapidly degraded after the above-mentioned multiple treatments.

[0060] When the additional oxidation step adopts scheme ②, and when an electrolytic cell is used to perform an electrochemical reduction reaction on the reaction solution between step (2) and the additional oxidation step, or between two additional oxidation steps, it is preferred that the reaction solution that has completed the Fenton oxidation reaction be used as the cathode electrolyte of the electrolytic cell for reduction reaction under acidic conditions, and the resulting liquid be subjected to Fenton oxidation reaction again. In this way, when the electrolytic operation performs the reduction reaction, the trivalent iron ions are reduced to ferrous ions Fe 2+ To reduce hydrogen evolution, after the electrochemical reduction reaction is complete, the solution can be directly added with hydrogen peroxide at an acidic pH, without the need for a new iron source, or with only a small amount of iron source added to proceed with the Fenton oxidation reaction. This conserves iron source while reducing the precipitation of iron hydroxides mixed with wastewater pollutants. Since iron hydroxides, once formed, co-precipitate with pollutants in the wastewater, the waste residue obtained after solid-liquid separation is mixed with many wastewater pollutants, making it hazardous waste.

[0061] The present invention can also be improved as follows: in order to make the filtrate E produced in step (4) reach a higher treatment standard, the filtrate E obtained in step (4) is further treated by a reverse osmosis device to obtain a clear liquid and a concentrated liquid. The pollutant content of the obtained clear liquid reaches the quality of the clear liquid obtained in the prior art, and the pollutant content is usually lower, so it can be directly discharged or retained in the subsequent process as clean water for dilution of turbid water. Preferably, the obtained concentrated liquid is used as the liquid to be treated or part of it is returned to the operation treatment of step (1) or step (2). Since the pollutant content in the landfill leachate has been greatly reduced after the degradation treatment step of the chemical method of the present invention; at this time, the reverse osmosis device is used to concentrate the liquid, which can greatly reduce the processing burden of the reverse osmosis device compared with the prior art, significantly extend the service life of the equipment consumables, and thus reduce its use cost.

[0062] The second object of the present invention is achieved through the following solutions.

[0063] A device for treating landfill leachate by chemically degrading it efficiently is characterized by comprising a gas-liquid mixing reaction tank, a chemical reaction tank, and an oxidizing gas generator; wherein,

[0064] The gas-liquid mixed reaction tank is connected to the chemical reaction tank via a pipeline, and the oxidizing gas generator is connected to the gas-liquid mixed reaction tank via a pipeline.

[0065] The gas-liquid mixing reaction tank is a device for reacting landfill leachate or oxidation reaction liquid with chlorine and / or ozone; the chemical reaction tank is a device for chemical reactions between solutions or between solutions and solid substances;

[0066] The oxidizing gas generator is an ozone generator or a chlorine generator, which is used to provide ozone or chlorine to react chemically with the landfill leachate or the oxidation reaction liquid.

[0067] When more than one gas-liquid mixing reaction tank and / or more than one chemical reaction tank are provided, the tanks are connected in series through pipelines, the first tank is the gas-liquid mixing reaction tank, and at least one gas-liquid mixing reaction tank is connected to the chemical reaction tank through a pipeline.

[0068] The gas-liquid mixing reaction tank is specifically selected from any one of a bubbling gas-liquid mixing reaction tank, a vacuum jet gas-liquid mixing reaction tank, and a spray tower gas-liquid mixing reaction tank.

[0069] Preferably, the ozone generator is a device that converts oxygen into ozone through the action of a high-frequency and high-voltage electric field; the oxygen used is specifically commercial oxygen and / or oxygen produced by ordinary chemical reactions and / or oxygen produced by electrolysis.

[0070] The chlorine generator described in the present invention is a reaction tank for commercial chlorine and / or chlorine produced by common chemical reaction and / or an electrolytic tank for chlorine produced by electrolysis.

[0071] The present invention can be improved as follows: a protein reaction flocculation tank is added, which is connected to the gas-liquid mixing reaction tank through a pipeline and is used to acidify the landfill leachate to cause the protein in the landfill leachate to react and denature to produce flocculants.

[0072] The present invention can be improved as follows: a temporary storage tank is added, which is connected to at least one of the protein reaction flocculation tank, the gas-liquid mixing tank, and the chemical reaction tank through a pipeline, or is set on at least one connecting pipeline between any two of the above three tanks, for temporary storage of the solution or overflow buffering.

[0073] The present invention can be improved as follows: at least one solid-liquid separator is added to separate the solid-liquid mixture produced during the solution reaction. Each solid-liquid separator is connected to any one, two, or more of the protein reaction flocculation tank, gas-liquid mixing tank, chemical reaction tank, and temporary storage tank via a pipeline to separate the solid-liquid mixture in the tank, or is installed on at least one connecting pipeline between any two of the four types of tanks to separate the solid-liquid mixture in one or more of the tanks and transfer the filtrate to another tank or tanks. Preferably, the solid-liquid separator is selected from any one of a centrifuge, a filter, and a filter press.

[0074] The present invention can be improved as follows: a solution acidity and alkalinity pH value adjustment tank is added and connected to at least one of the protein reaction flocculation tank, gas-liquid mixing tank, chemical reaction tank, solid-liquid separator, and temporary storage tank through a pipeline, or is set on at least one connecting pipeline between any two of the above five devices, so as to facilitate independent adjustment of the pH value of the reaction solution.

[0075] The present invention can be improved by adding a reverse osmosis device connected to the chemical reaction tank and / or solid-liquid separator and / or temporary storage tank via a pipeline to further process the original filtrate E, so that the dissolved matter and impurities in the filtrate E can be separated from the water. The equipment structure can be used in a one-stage, two-stage, or multi-stage series progressive manner, so that the final clear liquid produced can meet higher process requirements.

[0076] The present invention can also be improved as follows: an electrolytic cell with an anode tank area and a cathode tank area is added, connected to at least one of the protein reaction flocculation tank, gas-liquid mixing tank, chemical reaction tank, solid-liquid separator, temporary storage tank, and solution pH adjustment tank through a pipeline, or is set on at least one connecting pipeline between any two of the aforementioned six devices, for electrochemical oxidation and / or reduction reaction of the reaction liquid, so that difficult-to-degrade organic pollutants are degraded through the electrolytic cell. The electrolytic cell is divided into an anode tank area and a cathode tank area by a structure or an electrolytic cell separator. The electrolytic cell separator is one or more of a reverse osmosis membrane, a cation exchange membrane, an anion exchange membrane, a bipolar membrane, and an ion-free porous diaphragm, used alone or in combination, or in combination with a filter cloth. Preferably, a reverse osmosis membrane and / or a cation exchange membrane are used to maximize the performance of the electrolytic cell in treating organic wastewater.

[0077] The present invention can also be improved by adding an agitator to the protein reaction flocculation tank, / or the gas-liquid mixing tank, / or the chemical reaction tank, / or the temporary storage tank, / or the solution pH adjustment tank, / or the electrolytic tank to ensure that the reaction solution reacts at a uniform concentration, temperature, and viscosity. Specifically, agitators include impeller agitators and liquid flow agitators.

[0078] The present invention can also be improved as follows: a hot and cold temperature exchanger is added to the protein reaction flocculation tank and / or the gas-liquid mixing tank and / or the chemical reaction tank and / or the temporary storage tank and / or the solution pH adjustment tank and / or the electrolytic tank so that the temperature of the reaction solution can be controlled according to the process requirements.

[0079] The present invention can also be improved as follows: an exhaust gas processor is added and connected to the exhaust gas outlet of the protein reaction flocculation tank and / or the gas-liquid mixing tank and / or the chemical reaction tank and / or the solid-liquid separator and / or the temporary storage tank and / or the solution pH adjustment tank and / or the electrolytic tank to perform environmentally friendly treatment on the exhaust gas produced by each device during operation.

[0080] The present invention can also be improved by adding a programmable logic controller (PLC) and a sensor, wherein the sensor is located in the protein reaction flocculation tank, / or the gas-liquid mixing tank, / or the chemical reaction tank, / or the temporary storage tank, / or the solution pH adjustment tank, and / or the electrolytic tank, so that the apparatus of the present invention can automatically perform sampling and detection and automatically and safely operate according to a preset process flow. The sensor is at least one of a liquid level meter, a thermometer, a pH meter, a hydrometer, an oxidation-reduction potentiometer (ORP meter), a photoelectric colorimeter, a pressure gauge, an online COD detector, and a hydrogen concentration detector.

[0081] The present invention can also be improved by adding a heat treatment furnace to perform high-temperature treatment on the iron hydroxide filter residue containing organic impurities. Preferably, a rotary high-temperature electric furnace is used to make the produced iron oxide into a fine powder, which is more conducive to recycling as raw material.

[0082] Compared with the prior art, the present invention has the following beneficial effects:

[0083] 1. Compared with the existing first-class biochemical treatment + membrane filtration and second-class full-membrane adsorption filtration processes, the process of the present invention has a better degradation treatment effect on organic pollutants. Compared with the third-class low-consumption evaporation + ion exchange treatment process, the process of the present invention is simple, has low energy consumption, and low operating costs. It does not require the use of reverse osmosis processes or ion exchange processes that require frequent replacement of expensive consumables. However, when the reverse osmosis process can be used for supplementary treatment, not only can a clear liquid with the quality of the existing technology or even a lower pollutant content be obtained, but the frequency of consumable replacement is also much lower than that of the existing technology, which can significantly reduce the operating cost of the reverse osmosis device.

[0084] 2. The process of the present invention is simple to operate, has high degradation efficiency, requires little equipment space and investment, and has good economic benefits for treating organic waste liquid by chemical methods.

[0085] 3. The process of the present invention considers the health of workers from the perspective of occupational hygiene. In the earliest process step, an oxidant is used to kill biological pathogens in the landfill leachate, thereby preventing the harm of biological pathogens to the environment and human body in the subsequent steps of the process. Compared with the existing technology process that does not disinfect the treated liquid for biological pathogens, the present invention is more in line with the requirements of the "Work Safety Law".

[0086] 4. The present invention significantly reduces the metal ion content in the landfill leachate. Furthermore, when the landfill leachate or the oxidation reaction liquid B is treated by a chemical softening method in step (1), the present invention can effectively remove the metal ions in the landfill leachate, reduce the clogging of the electrolytic cell diaphragm and / or reverse osmosis membrane, extend the service life of the equipment, and reduce the equipment maintenance cost.

[0087] 5. The process and equipment of the present invention can treat all landfill leachate, so that no concentrated liquid is returned to the landfill area, and the landfill leachate is truly treated thoroughly in an environmentally friendly manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] FIG1 is a process flow diagram illustrating a method and apparatus for treating landfill leachate by chemically efficiently degrading the same according to embodiment 1 of the present invention;

[0089] FIG2 is a process flow diagram illustrating a method and apparatus for treating landfill leachate by chemically efficiently degrading the same according to Example 2 of the present invention;

[0090] Figure 2-1 is an enlarged view of part A in Figure 2;

[0091] Figure 2-2 is an enlarged view of part B in Figure 2;

[0092] FIG3 is a process flow diagram illustrating a method and apparatus for treating landfill leachate by chemically efficiently degrading the same according to Example 3 of the present invention;

[0093] Figure 3-1 is an enlarged view of part A in Figure 3;

[0094] Figure 3-2 is an enlarged view of part B in Figure 3;

[0095] Figure 3-3 is an enlarged view of part C in Figure 3;

[0096] FIG4 is a process flow diagram illustrating a method for treating landfill leachate by chemically efficiently degrading the landfill leachate and its equipment according to Example 4 of the present invention;

[0097] Figure 4-1 is an enlarged view of part A in Figure 4;

[0098] Figure 4-2 is an enlarged view of part B in Figure 4;

[0099] Figure 4-3 is an enlarged view of part C in Figure 4;

[0100] FIG5 is a process flow diagram illustrating embodiment 5 of a method for treating landfill leachate by chemically efficiently degrading the landfill leachate and its equipment according to the present invention.

[0101] Figure 1-protein reaction flocculation tank, 2-acidity and alkalinity pH adjustment tank, 3-solid-liquid separator, 4-gas-liquid mixing reaction tank, 5-chemical reaction tank, 6-oxidizing gas generator, 7-reverse osmosis treatment device, 8-electrolytic tank, 9-impeller agitator, 10-liquid flow agitator, 11-cold and hot temperature exchanger, 12-tank top gas collecting cover, 13-exhaust gas processor, 14-programmed logic controller PLC, 15-sensor, 16-acidic substance, 17-alkaline substance, 18-protein flocculent, 19-reverse osmosis treatment equipment produces concentrated solution, 20-reverse osmosis treatment device produces clear solution, 21-overflow buffer tank, 22-temporary storage tank, 23-valve, 24-pump, 25-oxidant, 26-garbage Leachate raw liquid, 27-exhaust gas processor absorption reaction liquid, 28-filtrate A, 29-oxidation reaction liquid B, 30-oxidation reaction liquid C, 31-solid-liquid mixture D, 32-filtrate E, 34-ferric hydroxide residue containing organic contamination impurities, 35-ferrous sulfate, 36-ferrous chloride, 37-electric furnace, 38-iron oxide, 39-hydrogen high-altitude discharge pipe, 40-bubbler, 41-vacuum ejector, 42-spray tower, 43-insoluble metal salt and / or metal hydroxide residue, 44-electrolytic cell partition, 45-solution after electrolysis treatment in the electrolytic cell, 46-ferrous hydroxide. DETAILED DESCRIPTION

[0102] The present invention will be further described below through specific embodiments.

[0103] The chlorine generator, 80-liter protein reaction flocculation tank, 80-liter gas-liquid mixing reactor, 80-liter pH adjustment tank, 100-liter chemical reaction tank, 500-liter temporary storage tank, electrolytic cell with an 80-liter anode and 80-liter cathode compartments, agitator, and exhaust gas treatment unit used in the embodiments of the present invention are all products of Yegao Environmental Protection Equipment Manufacturing Co., Ltd. in Foshan, Guangdong Province, China. The ozone generator, programmable logic controller (PLC), sensors, hot and cold temperature exchangers, electrolytic cell separators, electrolysis power supply, pumps, and valves are all commercially available products. The chemical raw materials used are commercially available. In addition to those listed above, those skilled in the art may also select other products with similar performance to those listed above, based on routine selection, to achieve the objectives of the present invention.

[0104] Example 1

[0105] As shown in FIG1 , this is a process flow diagram illustrating Example 1 of a method for treating landfill leachate by chemically efficiently degrading the same and its equipment. The equipment includes a protein reaction flocculation tank 1, two solid-liquid separators 3, a gas-liquid mixing reaction tank 4, a chemical reaction tank 5, an oxidizing gas generator 6, four temporary storage tanks 22, a plurality of valves 19, and a pump 20.

[0106] The protein reaction flocculation tank 1 is connected to the gas-liquid mixing reaction tank 4 through the solid-liquid separator 3-1 and the temporary storage tank 22-4; the gas-liquid mixing reaction tank 4 is connected to the chemical reaction tank 5; the gas-liquid mixing reaction tank 4 is also connected to the oxidizing gas generator 6; the chemical reaction tank 5 is also connected to the solid-liquid separator 3-2.

[0107] The gas-liquid mixing reaction tank 4 is a gas-liquid mixing bubbling reaction tank.

[0108] The solid-liquid separators 3-1 and 3-2 are filter presses.

[0109] The acidic substance 16 is a mixture of hydrochloric acid and sulfuric acid. The alkaline substance 17 is sodium hydroxide.

[0110] The ferrous sulfate 35 and ferrous chloride 36 are both solid substances.

[0111] The oxidizing agent 25 is hydrogen peroxide. The oxidizing gas generator 6 is an ozone generator.

[0112] The operation steps of the landfill leachate treatment in this embodiment are as follows:

[0113] 1. The landfill leachate stock solution 26 is added to the protein reaction flocculation tank 1, the stirrer 9-1 is turned on, and the acidic substance 16 is added to the protein reaction flocculation tank 1 to adjust the pH value of the solution to pH 5.5 and react for 2 hours. Protein flocculants appear in the reaction solution.

[0114] 2. Start pump 24-1 to pump the solid-liquid mixture from the protein reaction flocculation tank 1 to the solid-liquid separator 3-1 for solid-liquid separation to obtain filtrate A and filter residue A. Filtrate A 28 is drained to the temporary storage tank 22-2 for temporary storage, and filter residue A, i.e., protein flocculants 18, is temporarily stored in tank 22-1.

[0115] 3. The acidic filtrate A is drained into the gas-liquid mixed reaction tank 4 to react with ozone for 3 hours to obtain the oxidation reaction liquid B.

[0116] 4. The acidic oxidation reaction solution B is added to the chemical reaction tank 5 and an acidic substance 16 is added to adjust the pH value of the solution to pH 3.5. Subsequently, ferrous sulfate, ferrous chloride, hydrogen peroxide, and sodium hydroxide are added to maintain the pH of the reaction solution at 3.5 and perform Fenton oxidation for 2 hours. After the oxidation reaction is completed, an alkaline substance 17 is added to adjust the pH value of the solution to pH 4 to generate ferric hydroxide precipitate in the solution.

[0117] 5. The solid-liquid mixture in the chemical reaction tank 5 is extracted for solid-liquid separation to obtain filter residue 34 and filtrate E 32.

[0118] Through these five manual steps, the landfill leachate is treated according to process requirements, bringing its organic matter content up to the standard required for entry into the municipal sewage network. After treatment, the content of metal ions other than potassium and sodium in the leachate decreased by 77%. The COD test data for the organic wastewater treatment solution in each process step are listed in Table 1.

[0119] Example 2

[0120] As shown in FIG2 , this is a process flow diagram illustrating Example 2 of a method for treating landfill leachate by chemically efficiently degrading the same and its equipment according to the present invention. The equipment includes a protein reaction flocculation tank 1, three solid-liquid separators 3, two gas-liquid mixing reaction tanks 4, a chemical reaction tank 5, two oxidizing gas generators 6, a reverse osmosis treatment device 7, two impeller agitators 9, two tail gas treatment tanks 13, an overflow buffer tank 21, a plurality of temporary storage tanks 22, a plurality of valves and pumps.

[0121] Protein reaction flocculation tank 1 is connected to gas-liquid mixing reaction tanks 4-1 and 4-2 in series via solid-liquid separator 3-1 and overflow buffer tank 21-1. Gas-liquid mixing reaction tank 4-2 is connected to chemical reaction tank 5. Chemical reaction tank 5 is connected to reverse osmosis treatment device 7 via solid-liquid separators 3-2 and 3-3 and temporary storage tank 22-3. Reverse osmosis treatment device 7 is connected to gas-liquid mixing reaction tank 4-1 via temporary storage tank 22-5. Protein reaction flocculation tank 1 is also connected to exhaust gas processor 13-1. Gas-liquid mixing reaction tanks 4-1 and 4-2 are also connected to oxidizing gas generators 6-1 and 6-2, respectively.

[0122] The solid-liquid separator 3-1 is a centrifuge and 3-2 is a filter press.

[0123] The gas-liquid mixing reaction tanks are all vacuum jet reaction tanks.

[0124] The oxidizing gas generator 6-1 is a chlorine generator, and 6-2 is an ozone generator.

[0125] The sensor 15-1 is a pH meter, 15-2 is a liquid level meter, 15-3 is a pH meter, 15-4 is an ORP meter, and 15-5 is an online COD detector.

[0126] The acidic substance 16 is sulfuric acid, the alkaline substance 17 is potassium hydroxide, and the oxidant 25 is hydrogen peroxide.

[0127] The operation steps of the garbage leachate treatment in this embodiment are as follows:

[0128] 1. Add the landfill leachate solution 26 to the protein reaction flocculation tank 1. Start the agitator 9-1 and add the acidic substance 16 to the protein reaction flocculation tank 1 to adjust the pH value of the solution to pH 4. The solution is reacted for 1 hour. Precipitated floccules appear in the reaction solution. At the same time, hydrogen peroxide is added to the reaction solution to kill microorganisms and oxidize organic matter. The overflow exhaust gas from the protein reaction flocculation tank 1 is drained to the tank 13-1 for environmental treatment.

[0129] 2. Start pump 24-1 to pump the solid-liquid mixture in protein reaction flocculation tank 1 to centrifuge 3-1 for separation to obtain filtrate A and residue A.

[0130] 3. The acidic filtrate A is fed into the gas-liquid mixed reaction tank 4-1 through the overflow buffer tank 21-1 to undergo an oxidation reaction with chlorine for 1.5 hours. The acidic filtrate A is then pumped by the pump 24-5 to the gas-liquid mixed reaction tank 4-2 to continue the oxidation reaction with ozone for 1.5 hours to obtain the oxidation reaction liquid B.

[0131] 4. The oxidation reaction liquid B is added to the chemical reaction tank 5 for Fenton oxidation reaction. During the process, sensor 15-2 controls the addition of oxidation reaction liquid B, sensor 15-3 controls the addition of alkaline substance 17, and sensor 15-4 controls the addition of ferrous sulfate and hydrogen peroxide. The Fenton oxidation reaction is maintained at pH 3.8 for 1 hour to obtain oxidation reaction liquid C.

[0132] 5. Adding alkaline substance 17 to the oxidation reaction solution C in the chemical reaction tank 5 to adjust the pH value of the solution to pH 5 so that the solution generates iron hydroxide precipitate.

[0133] 6. The solid-liquid mixture in step 5 is separated by solid-liquid separators 3-2 and 3-3 to obtain filter residue 34 and filtrate E 32-1.

[0134] 7. The filtrate E32-1 is pumped into the reverse osmosis treatment device 7 for treatment to obtain a clear liquid 20 and a concentrated liquid 19, wherein the concentrated liquid 19 is returned to the gas-liquid mixing reaction tank 4-1 for re-treatment.

[0135] 8. The clear liquid 20 in the temporary storage tank 22-4 is added to the temporary storage tank 22-6. The solution in the tank 22-3 is controlled to be mixed under the detection of the COD detector 15-5. After the mixed liquid in the temporary storage tank 22-6 reaches the process treatment standard, it becomes the solution 32-2 for external discharge or further treatment.

[0136] 9. During the treatment process, the exhaust gas G escaping from multiple reaction tanks is led to tank 13-2 for environmental protection treatment.

[0137] Through the above steps, the landfill leachate was treated according to process requirements, bringing its organic matter content up to the standard required for entry into the municipal sewage network. After treatment, the content of metal ions other than potassium and sodium in the landfill leachate decreased by 85%. The COD test data for each stage of organic wastewater treatment are listed in Table 1.

[0138] Example 3

[0139] As shown in FIG3 , this is a process flow diagram illustrating Example 3 of a method for treating landfill leachate by chemical degradation with high efficiency and its equipment according to the present invention. The equipment includes a chemical reaction flocculation tank 1, four pH adjustment tanks 2, eight solid-liquid separators 3, a gas-liquid mixing reaction tank 4, three chemical reaction tanks 5, an oxidizing gas generator 6, an electrolytic tank 8, four impeller stirrers 9, four liquid flow stirrers 10, two tail gas treatment tanks 13, twenty-one sensors 15, eight temporary storage tanks 22, and multiple valves and pumps.

[0140] The protein reaction flocculation tank 1 is connected to the acid-base pH adjustment tank 2-1 through the solid-liquid separator 3-1, and then connected to the gas-liquid mixing reaction tank 4 through the solid-liquid separator 3-2.

[0141] The gas-liquid mixing reaction tank 4 and the chemical reaction tank 5-1 are connected in a liquid circulation manner via the pH adjustment tank 2-2, the solid-liquid separators 3-3 and 3-4, and the pH adjustment tank 2-3. The gas-liquid mixing reaction tank 4 is also connected to the chemical reaction tank 5-2 via the temporary storage tank 22-3.

[0142] The chemical reaction tank 5-2 is connected to the anode tank area of ​​the electrolytic cell 8 via the solid-liquid separators 3-5 and 3-6 and the pH adjustment tank 2-4. The anode tank area of ​​the electrolytic cell 8 is connected to the cathode tank area via the temporary storage tank 22-5. The cathode tank area of ​​the electrolytic cell 8 is connected to the chemical reaction tank 5-3 via the temporary storage tank 22-6.

[0143] The solid-liquid separators 3-1, 3-3, 3-5 and 3-7 are filter presses, and the solid-liquid separators 3-2, 3-4, 3-6 and 3-8 are ordinary filters.

[0144] The oxidizing gas generator 6 is an ozone generator, and is connected to the gas-liquid mixing reaction tank 4 .

[0145] The exhaust gas processor 13-1 is specifically used to absorb and treat the gas escaping from the protein reaction flocculation tank 1. The exhaust gas processor 13-2 is used to absorb the exhaust gas G discharged from other tanks in the equipment for environmental protection. The absorption reaction liquid 27 in the exhaust gas processor is all sodium hydroxide solution.

[0146] The sensor 15-1 is a liquid level meter, 15-2 is a pH meter, 15-3 is a pH meter, 15-4 is a liquid level meter, 15-5 is an ORP meter, 15-6 is a pH meter, 15-7 is a liquid level meter, 15-8 is an ORP meter, 15-9 is a pH meter, 15-10 is a pH meter, 15-11 is a liquid level meter, 15-12 is a pH meter, 15-13 is an ORP meter, 15-14 is a liquid level meter, 15-15 is a pH meter, 15-16 is an ORP meter, 15-17 is an ORP meter, 15-18 is a liquid level meter, 15-19 is a pH meter, 15-20 is an ORP meter, and 15-21 is a pH meter.

[0147] In the electrolytic cell 8 with an anode cell and a cathode cell, the anode cell is used for oxidation treatment of the acidic organic waste liquid, and the cathode cell is used for reduction treatment of the acidic organic waste liquid.

[0148] The acidic substance 16 is a sulfuric acid solution.

[0149] The alkaline substance 17-1 is a mixture of sodium hydroxide (potassium), sodium carbonate (potassium), and sodium bicarbonate (potassium), and 17-2 is a sodium hydroxide solution.

[0150] The ferrous compounds are ferrous sulfate 35 and ferrous hydroxide 46.

[0151] The oxidant 25 is hydrogen peroxide.

[0152] The operation steps of the garbage leachate treatment in this embodiment are as follows:

[0153] 1. Add the landfill leachate stock solution 26 to the protein reaction flocculation tank 1, start the agitator 9-1 and add an acidic substance to the protein reaction flocculation tank 1 to adjust the pH value of the solution to pH 1. React for 0.5 hours to cause precipitated flocs to appear in the reaction solution. The exhaust gas escaping from the tank 1 is led to the exhaust gas treatment tank 13-1 for environmental protection treatment.

[0154] 2. Start pump 24-2 to pump the solid-liquid mixture in protein reaction flocculation tank 1 to filter press 3-1 for separation to obtain filtrate A and filter residue A. Drain filtrate A into pH adjustment tank 2-1 for pH adjustment. During the process, add alkaline substance 17-1 to adjust the pH of the solution to pH 11 and produce a precipitate.

[0155] 3. The solid-liquid mixture in the pH adjustment tank 2-1 is filtered through a filter 3-2 and the alkaline filtrate A 28 is fed into the gas-liquid mixed reaction tank 4. The pH value of the solution is adjusted to pH 7 and then reacted with ozone for 2 hours to obtain an oxidation reaction solution B 29.

[0156] 4. The oxidation reaction liquid B 29 is pumped to the pH adjustment tank 2-2 by pump 24-8, and an acidic substance 16 is added to adjust the pH value of the solution to pH 4, thereby making the oxidation reaction liquid B 29 an acidic solution.

[0157] 5. The acidic oxidation reaction liquid B 29 is added to the chemical reaction tank 5-1 to maintain the pH of the reaction liquid at 4 to carry out the Fenton oxidation reaction with ferrous sulfate and hydrogen peroxide. After the Fenton oxidation reaction is completed, the alkaline substance 17-2 is added to precipitate iron hydroxide in the reaction liquid.

[0158] 6. The solid-liquid mixture in the chemical reaction tank 5-1 is subjected to solid-liquid separation by means of a filter press 3-3 and a filter 3-4 to obtain a filter residue 34-1 and a filtrate E32-1. The filtrate E32-1 is pumped by means of a pump 24-10 to an acid-base pH adjustment tank 2-3 for acidification and pH adjustment, so that the pH value of the filtrate E32-1 is adjusted to pH 2.

[0159] 7. The acidic filtrate E32-1 in the pH adjustment tank 2-3 is fed back into the gas-liquid mixed reaction tank 4 to react with ozone for 2 hours. After completion, it is pumped to the temporary storage tank 22-3 by pump 24-7 for temporary storage.

[0160] 8. The acidic organic waste liquid 32-2 in the temporary storage tank 22-3 is added to the chemical reaction tank 5-2 for another Fenton oxidation reaction. During the process, ferrous sulfate, hydrogen peroxide, and sodium hydroxide are added respectively and the reaction is carried out for 2 hours while maintaining the pH of the reaction solution at 3.3. After the Fenton oxidation reaction is completed, an alkaline substance 17-2 is added to the reaction solution to produce ferric hydroxide precipitate.

[0161] 9. The solid-liquid mixture in the chemical reaction tank 5-2 is subjected to solid-liquid separation by means of a filter press 3-5 and a filter 3-6 to obtain a filter residue 34-2 and a filtrate E 32-3. The filtrate E 32-3 is drained into a pH adjustment tank 2-4 and sulfuric acid 16 is added to adjust the pH of the solution to pH 2.

[0162] 10. The acidic organic waste liquid E32-3 in the pH adjustment tank 2-4 is put into the anode tank area of ​​the electrolytic tank 8 for oxidation reaction for 2.5 hours, and the solution in the temporary storage tank 22-5 that has been oxidized in the electrolytic tank is put into the cathode tank area for reduction reaction for 2.5 hours, and the solution that has completed the cathode reduction reaction is drained to the temporary storage tank 22-6 for temporary storage.

[0163] 11. The solution 45 in the temporary storage tank 22-6 is pumped to the chemical reaction tank 5-3 by the pump 24-19 and maintained at pH 3 for Fenton oxidation reaction for 1 hour. After the reaction is completed, sodium hydroxide solution 17-2 is added to the reaction solution to adjust the pH value of the solution to pH 6 so that the reaction solution produces iron hydroxide precipitate.

[0164] 12. The mixture in the chemical reaction tank 5-3 is subjected to solid-liquid separation by a filter press 3-7 and a filter 3-8 to obtain a filter residue 34-3 and a filtrate E 32-4. The filtrate E 32-4 is the solution after the process.

[0165] 13. During the treatment process, some of the exhaust gas G escaping from the tanks in the equipment is drained into tank 13-2 for environmental protection treatment.

[0166] After the above 13 steps, the landfill leachate is treated and the recycling treatment method of steps (3) to (6) described in the scheme of the present invention is adopted, and an electrolytic cell is added for auxiliary oxidation and reduction reaction treatment, so that the treatment of the landfill leachate achieves a relatively ideal treatment effect.

[0167] Through the above steps, the landfill leachate was treated according to process requirements, bringing its organic matter content up to the standard required for entry into the municipal sewage network. After treatment, the content of metal ions other than potassium and sodium in the leachate decreased by 98%. Specific COD test data for each stage of treatment are listed in Table 1.

[0168] Example 4

[0169] As shown in FIG4 , there is a process flow diagram illustrating Example 4 of a method for treating landfill leachate by chemical degradation with high efficiency and the equipment thereof according to the present invention. The equipment includes a protein reaction flocculation tank 1, two pH adjustment tanks 2, seven solid-liquid separators 3, a gas-liquid mixing reaction tank 4, three chemical reaction tanks 5, an oxidizing gas generator 6, two electrolytic tanks 8, four impeller stirrers 9, two liquid flow stirrers 10, a hot and cold temperature exchanger 11, two tail gas treatment tanks 13, a PLC 14, twenty-one sensors 15, ten temporary storage tanks 22, an electric furnace 37, two hydrogen high-altitude safety discharge pipes 39, and multiple valves and pumps.

[0170] The protein reaction flocculation tank 1 is connected to the gas-liquid mixing reaction tank 4 via the solid-liquid separator 3-1 and the pH value adjustment tank 2-1. The gas-liquid mixing reaction tank 4 is connected to the chemical reaction tank 5-1.

[0171] The chemical reaction tank 5-1 is connected to the anode tank area of ​​the electrolytic tank 8-1 through the solid-liquid separators 3-2 and 3-3 and the temporary storage tank 22-2. The anode tank area of ​​the electrolytic tank 8-1 is connected to the cathode tank area through a pipeline. The cathode tank area of ​​the electrolytic tank 8-1 is connected to the chemical reaction tank 5-2 through the temporary storage tank 22-3.

[0172] Chemical reaction tank 5-2 is connected to the anode section of electrolytic cell 8-2 via solid-liquid separators 3-4 and 3-5, a temporary storage tank 22-5, and a pH adjustment tank 2-2. The anode section of electrolytic cell 8-2 is connected to the cathode section via a temporary storage tank 22-7. The cathode section of electrolytic cell 8-2 is connected to chemical reaction tank 5-3 via a temporary storage tank 22-8, while chemical reaction tank 5-3 is connected to the anode section of electrolytic cell 8-2 via a temporary storage tank 22-6. The acidic substance 16 is sulfuric acid. The alkaline substance 17 is sodium hydroxide. The tail gas absorption reaction liquid 27 is a sodium hydroxide solution. The oxidant 25 is hydrogen peroxide.

[0173] The electric furnace 37 is used for high temperature treatment of ferric hydroxide residue containing organic contamination impurities to produce ferric oxide raw material for reuse.

[0174] The gas-liquid mixing reaction tank 4 is a spray tower reaction tank.

[0175] The oxidizing gas generator 6 is an ozone generator, and is connected to the gas-liquid mixing reaction tank 4 .

[0176] The electrolytic cells 8-1 and 8-2 are both used for oxidation and reduction treatment of organic wastewater. The electrolytic cell separator 44-1 of the electrolytic cell 8-1 is a bipolar membrane, and the electrolytic cell separator 44-2 of the electrolytic cell 8-2 is a cation exchange membrane.

[0177] The solid-liquid separators 3-1, 3-3, 3-5 and 3-7 are common filters, and the solid-liquid separators 3-2, 3-4 and 3-6 are filter presses.

[0178] The sensor 15-1 is a liquid level meter, 15-2 is a pH meter, 15-3 is a pH meter, 15-4 is a thermometer, 15-5 is an ORP meter, 15-6 is a liquid level meter, 15-7 is a pH meter, 15-8 is an ORP meter, 15-9 is an ORP meter, 15-10 is an ORP meter, 15-11 is a liquid level meter, 15-12 is a pH meter, 15-13 is an ORP meter, 15-14 is a liquid level meter, 15-15 is a pH meter, 15-16 is an ORP meter, 15-17 is an ORP meter, 15-18 is a liquid level meter, 15-19 is a pH meter, 15-20 is an ORP meter, and 15-21 is a pH meter.

[0179] This embodiment also provides a programmable logic controller (PLC) 14, whose sensing signal input terminal is connected to the sensing signal output terminal of the sensor, and whose control signal output terminal is connected to the control signal input terminals of the oxidizing gas generator, the electrolysis power supply of the electrolytic cell, the hot and cold temperature exchanger, the pump, and the valve.

[0180] The operation steps of the garbage leachate treatment in this embodiment are as follows:

[0181] 1. Turn on the power to allow the equipment to perform on-site detection through PLC and sensors, and transmit the on-site detection data to the PLC for processing so that the equipment can run according to the preset program.

[0182] 2. The landfill leachate 26 is added to the protein reaction flocculation tank 1. The agitator 9-1 is started and sulfuric acid is added according to the PLC control to adjust the pH value of the solution to pH 2. The solution reacts for 1 hour to precipitate flocs. During this process, the escaping gas of the protein reaction flocculation tank 1 is directed to the exhaust gas processor tank 13-1 for treatment.

[0183] 3. Start pump 24-1 and pass the solid-liquid mixture in the protein reaction flocculation tank 1 through filter 3-1 for solid-liquid separation to obtain filter residue 18 and filtrate A, wherein filtrate A is drained into the acid-base pH adjustment tank 2-1 for pH adjustment.

[0184] 4. Add alkaline substance 17 to the pH adjustment tank 2-1, start the stirrer 10-1 and adjust the pH value of the filtrate A to pH 9.

[0185] 5. Add the alkaline organic waste liquid in the pH adjustment tank 2-1 to the gas-liquid mixed reaction tank 4 to react with ozone. The temperature of the reaction liquid is controlled at 30°C during the process. After 3 hours of oxidation reaction, oxidation reaction liquid B is obtained.

[0186] 6. The alkaline oxidation reaction liquid B was added to the chemical reaction tank 5-1 for Fenton oxidation reaction. The PLC controlled the process by adding acidic substances 16 to adjust the pH value of the reaction liquid to 3.2. Ferrous chloride, hydrogen peroxide, and sodium hydroxide were then added successively to maintain the pH at 3.2 for Fenton oxidation reaction for 2.5 hours. After the oxidation reaction was completed, sodium hydroxide was added to adjust the pH value of the reaction liquid to pH 8.5, and ferric hydroxide precipitate was precipitated.

[0187] 7. The solid-liquid mixture in the chemical reaction tank 5-1 is separated by the filter press 3-2 and the filter 3-3 to obtain filter residue 34-1 and alkaline filtrate E32, and the alkaline filtrate E32-1 is drained into the temporary storage tank 22-2 for temporary storage.

[0188] 8. Alkaline filtrate E 32 is added to the anode tank area of ​​electrolytic cell 8-1 for an oxidation reaction for 2 hours. After completion, the anolyte is pumped to the cathode tank area via pump 24-9 for a reduction reaction for 2 hours. The process is monitored by sensors 15-9 and 15-10 ORP meters for safety. After completion, the catholyte is pumped to temporary storage tank 22-3 for temporary storage.

[0189] 9. Add the solution from the temporary storage tank 22-3 to the chemical reaction tank 5-2 for Fenton oxidation reaction. Under PLC control, add 16g of sulfuric acid, 36g of ferrous chloride, 25g of hydrogen peroxide, and 17g of sodium hydroxide to maintain the pH value of the reaction solution at 3.8 and perform Fenton oxidation reaction for 2 hours.

[0190] 10. The solid-liquid mixture in the chemical reaction tank 5-2 is subjected to solid-liquid separation to obtain filter residue 34-2 and filtrate 32-2. The filtrate 32-2 is then drained into the temporary storage tank 22-5 for temporary storage.

[0191] 11. The solution in the temporary storage tank 22-5 is added to the acid-base pH adjustment tank 2-2 for pH adjustment. After adding sulfuric acid, the pH value of the solution is adjusted to pH 2.

[0192] 12. The acidic organic waste liquid in the pH adjustment tank 2-2 is pumped into the cathode tank area of ​​the electrolytic tank 8-2 through the pump 24-14 for a reduction reaction for 2 hours. After the reduction reaction is completed, it is transferred to the anode tank area for an oxidation reaction for 2 hours. After the oxidation reaction is completed, the anode electrolyte is pumped into the tank temporary storage 22-8 through the pump 24-18 for temporary storage.

[0193] 13. The acidic solution in the temporary storage tank 22-8 is added to the chemical reaction tank 5-3 for Fenton oxidation reaction. Under the control of PLC, 36% ferrous chloride, 25% hydrogen peroxide and 17% sodium hydroxide solution are added respectively to maintain the pH value of the reaction solution at 4 for 1.5 hours. After the Fenton oxidation reaction is completed, the pH value of the reaction solution is adjusted to pH 1.5.

[0194] 14. The acidic solution in the chemical reaction tank 5-3 is pumped back to the temporary storage tank 22-6 by pump 24-21 for temporary storage, and the electrolytic tank 8-2 is used again for multiple oxidation and reduction reactions. After the reaction is completed, the solution is again put into the chemical reaction tank 5-3 for Fenton oxidation reaction for 1.5 hours. Finally, sodium hydroxide solution 17 is added to adjust the pH value of the reaction solution to pH 7, and iron hydroxide precipitates are precipitated.

[0195] 15. Start pump 24-22 to separate the mixture in chemical reaction tank 5-3 into solid and liquid by filter press 3-6 and filter 3-7, and obtain filter residue 34-3 and filtrate 32-3, wherein filtrate 32-3 is the solution processed according to the process.

[0196] 16. Filter residues 34-2 and 34-3 are placed in an electric furnace 37 for high-temperature treatment. The resulting iron oxide is recycled as raw material. Filter residues 18 and 34-1 are treated as hazardous waste.

[0197] 17. The tail gas treatment tank 13-2 performs environmentally friendly treatment on the G tail gas escaping from each tank of the equipment.

[0198] During the treatment process, the organic waste liquid was subjected to acid and alkali oxidation and reduction electrochemical treatments using two electrolytic cells respectively. In addition, the electrolytic cell 8-2 was combined with the chemical reaction cell 5-3 to perform two repeated electrochemical oxidation and reduction treatments and two Fenton oxidation treatments, so that the organic matter in the landfill leachate could be degraded.

[0199] Through the above steps, the landfill leachate was treated according to process requirements, bringing its organic matter content up to the standard required for entry into the municipal sewage network. After treatment, the content of metal ions other than potassium and sodium in the leachate decreased by 90%. The COD test data for each stage of the process are listed in Table 1.

[0200] Example 5

[0201] As shown in FIG5 , this is a process flow diagram illustrating Example 5 of a method for treating landfill leachate by chemical degradation with high efficiency and the equipment thereof according to the present invention. The equipment includes a gas-liquid mixing reaction tank 4, a chemical reaction tank 5, an oxidizing gas generator 6, a solid-liquid separator 3, a temporary storage tank 22, a plurality of valves 19, and a pump 20.

[0202] The gas-liquid mixing reaction tank 4 is connected to the chemical reaction tank 5 ; the gas-liquid mixing reaction tank 4 is also connected to the oxidizing gas generator 6 ; the chemical reaction tank 5 is also connected to the solid-liquid separator 3 .

[0203] The gas-liquid mixing reaction tank 4 is a gas-liquid mixing bubbling reaction tank.

[0204] The solid-liquid separator 3 is a filter press.

[0205] The acidic substance 16 is a mixed solution of sulfuric acid. The alkaline substance 17 is potassium hydroxide.

[0206] The ferrous sulfate 35 is a saturated aqueous solution thereof.

[0207] The oxidizing agent 25 is hydrogen peroxide. The oxidizing gas generator 6 is an ozone generator.

[0208] The operation steps of the landfill leachate treatment in this embodiment are as follows:

[0209] 1. The landfill leachate raw liquid 26 is fed into the gas-liquid mixed reaction tank 4 to react with ozone for 6 hours to obtain oxidation reaction liquid B.

[0210] 2. The oxidation reaction solution B is added to the chemical reaction tank 5 and an acidic substance 16 is added to adjust the pH value of the solution to pH 3.5. Subsequently, ferrous sulfate, hydrogen peroxide, and potassium hydroxide are added to maintain the pH of the reaction solution at 3.5 for Fenton oxidation reaction for 2 hours. After the oxidation reaction is completed, an alkaline substance 17 is added to adjust the pH value of the solution to pH 8 to produce ferric hydroxide precipitate in the solution.

[0211] 3. The solid-liquid mixture in the chemical reaction tank 5 is extracted for solid-liquid separation to obtain a filter residue 34.

[0212] 4. The filter residue obtained in step 3 is returned to the chemical reaction tank 5, and the operations of steps 2 and 3 are repeated three times to obtain filter residue 34 and filtrate E.

[0213] Through the above-mentioned operation steps, Examples 1 to 5 of the present invention can treat landfill leachate according to the process requirements, and can make its organic matter content reach the standard for entering the urban sewage network. After the landfill leachate is treated, no concentrated liquid is produced, and no re-injection is required, thereby achieving complete treatment of the landfill leachate. Among them, when the present invention uses reverse osmosis equipment to treat landfill leachate, as in Example 2, the concentrated liquid produced is returned to step (1) or step (2) for treatment, achieving complete treatment of the landfill leachate. After the treatment is completed, the content of metal ions other than potassium and sodium in the landfill leachate decreases by 80%. The COD test data of the solution treated with organic waste liquid in each process step are listed in Table 1.

[0214] Table 1 COD value test results of the treated solution at each stage in the process of treating landfill leachate in Example

Claims

1. A method for treating landfill leachate by chemical degradation with high efficiency, characterized in that: The following steps are involved: (1) subjecting the landfill leachate to oxidation reaction with an oxidizing gas in a gas-liquid mixing reactor to obtain an oxidation reaction liquid B; (2) subjecting the oxidation reaction liquid B to a Fenton oxidation reaction under acidic conditions to obtain an oxidation reaction liquid C; (3) adding an alkaline substance into the oxidation reaction solution C to cause a reaction in the solution to produce a precipitate and obtain a solid-liquid mixture D; (4) The solid-liquid mixture D is subjected to solid-liquid separation to obtain a filter residue E and a filtrate E, wherein the filtrate E is a solution that has been processed according to the process.

2. The method for treating landfill leachate according to claim 1, characterized in that: The oxidizing gas is chlorine and / or ozone.

3. The method for treating landfill leachate according to claim 2, characterized in that: The landfill leachate in step (1) reacts with an oxidizing gas under acidic, alkaline or neutral conditions; If the landfill leachate is subjected to a reaction with an oxidizing gas under alkaline conditions and the landfill leachate itself does not reach the set alkaline conditions, an alkaline pH adjuster needs to be added to the landfill leachate to convert the reaction liquid into an alkaline solution before reacting with the oxidizing gas; the alkaline pH adjuster is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

4. The method for treating landfill leachate according to claim 3, characterized in that: In step (2), the oxidation reaction liquid B is subjected to a Fenton oxidation reaction under acidic conditions; the Fenton oxidation reaction is a process in which at least one of ferrous hydroxide, ferrous sulfate and ferrous chloride reacts with hydrogen peroxide in the oxidation reaction liquid B to generate hydroxyl radicals to oxidatively degrade organic matter; when the oxidation reaction liquid B is an alkaline solution, an acidic pH adjuster is added to adjust it to acidic before the Fenton oxidation reaction is carried out; the acidic pH adjuster is hydrochloric acid and / or sulfuric acid.

5. The method for treating landfill leachate according to claim 4, characterized in that: In step (3), the alkaline substance is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

6. The method for treating landfill leachate according to claim 5, characterized in that: Prior to step (1), the landfill leachate is first mixed with an acidic substance for an acidification reaction, so that the protein in the landfill leachate is denatured and coagulated into flocs to obtain a solid-liquid mixture; the obtained solid-liquid mixture is subjected to solid-liquid separation to obtain an acidic filtrate A and a filter residue A, and the acidic filtrate A is used to carry out the treatment of steps (1) to (4).

7. The method for treating landfill leachate according to claim 6, characterized in that: After the acidification treatment prior to step (1) is completed, hydrogen peroxide is added to the obtained solid-liquid mixture to kill the pathogens therein.

8. The method for treating landfill leachate according to claim 7, characterized in that: The electrolytic cell with an anode tank area and a cathode tank area is used to perform a reduction reaction on the treated liquid in at least one of the following situations: (i) before step (1); (ii) before step (2); (iii) after step (2); (iv) After step (4).

9. The method for treating landfill leachate according to claim 8, characterized in that: At least one oxidation step is added in at least one of the following cases: (i) before step (2); (ii) after step (2); (iii) after step (4); The oxidation step is selected from at least one of the following schemes: Scheme ① uses oxidizing gas to perform oxidation reaction in a gas-liquid mixing reactor; Scheme ②: Fenton oxidation reaction is carried out under acidic conditions; Scheme ③ uses an electrolytic cell with an anode tank area and a cathode tank area, and performs an electrochemical oxidation reaction in the anode tank area; Among them, the oxidation step added after step (4) is only selected from the above-mentioned scheme ① or scheme ③.

10. The method for treating landfill leachate according to claim 9, characterized in that Before and / or after the at least one additional oxidation step, the cathode tank area of ​​the electrolytic cell provided with an anode tank area and a cathode tank area is used to perform an electrochemical reduction reaction on the reaction liquid, and the reaction liquid is treated by a combination of repeated oxidation-reduction reactions, that is, more than one oxidation step and at least one electrolytic reduction reaction step are performed alternately, so that the organic matter in the waste liquid is quickly degraded after the above-mentioned multiple treatments.

11. The method for treating landfill leachate according to claim 10, characterized in that: In order to make the filtrate E prepared in step (4) reach a higher treatment standard, the filtrate E obtained in step (4) is further treated by a reverse osmosis device to obtain a clear liquid and a concentrated liquid; the obtained clear liquid is directly discharged or retained in a subsequent process as clean water for diluting turbid water, and the obtained concentrated liquid is returned to step (1) or step (2) as a liquid to be treated or part of it.

12. A device for treating landfill leachate using the landfill leachate treatment method according to claim 1, characterized in that: It includes a gas-liquid mixing reaction tank, a chemical reaction tank, and an oxidizing gas generator; wherein, The gas-liquid mixed reaction tank is connected to the chemical reaction tank via a pipeline, and the oxidizing gas generator is connected to the gas-liquid mixed reaction tank via a pipeline; The gas-liquid mixed reaction tank is a device used for reacting garbage leachate or oxidation reaction liquid with chlorine and / or ozone; the chemical reaction tank is a device used for chemical reactions between solutions or between solutions and solid substances; The oxidizing gas generator is an ozone generator or a chlorine generator, which is used to provide ozone or chlorine to react chemically with the landfill leachate or the oxidation reaction liquid.

13. The device according to claim 12, characterized in that When more than one gas-liquid mixing reaction tank and / or more than one chemical reaction tank are provided, the tanks are connected in series through pipelines, the leading tank is the gas-liquid mixing reaction tank, and at least one gas-liquid mixing reaction tank is connected to the chemical reaction tank through a pipeline.

14. The device according to claim 13, characterized in that A protein reaction flocculation tank is added, and the protein reaction flocculation tank is connected to the gas-liquid mixing reaction tank through a pipeline, and is used for acidifying the garbage leachate to cause the protein in the garbage leachate to react and denature to produce flocculants.

15. The device according to claim 14, characterized in that A temporary storage tank is added, which is connected to at least one of the protein reaction flocculation tank, the gas-liquid mixing tank, and the chemical reaction tank through a pipeline, or is set on at least one connecting pipeline between any two of the above three tanks, and is used for temporary storage of the solution or overflow buffering.

16. The device according to claim 15, characterized in that At least one solid-liquid separator is added to separate the solid-liquid mixture produced during the solution reaction process; each of the solid-liquid separators is connected to any one or two or more of the protein reaction flocculation tank, the gas-liquid mixing tank, the chemical reaction tank, and the temporary storage tank through a pipeline, or is arranged on at least one connecting pipeline between any two of the above four tanks.

17. The device according to claim 16, characterized in that A solution acidity and alkalinity pH value adjustment tank is added and connected to at least one of the protein reaction flocculation tank, gas-liquid mixing tank, chemical reaction tank, solid-liquid separator, and temporary storage tank through a pipeline, or is set on at least one connecting pipeline between any two of the above five devices, so as to facilitate independent adjustment of the pH value of the reaction solution.

18. The device according to claim 17, characterized in that An electrolytic cell with an anode tank area and a cathode tank area is added, connected to at least one of the protein reaction flocculation tank, gas-liquid mixing tank, chemical reaction tank, solid-liquid separator, temporary storage tank, and solution acid-base pH adjustment tank through a pipeline, or is set on at least one connecting pipeline between any two of the above six devices, for electrochemical oxidation and / or reduction reaction treatment of the reaction liquid, so that the organic pollutants that are difficult to degrade are degraded through the electrolytic cell; The electrolytic cell is divided into an anode cell area and a cathode cell area by a structure or an electrolytic cell separator. The electrolytic cell separator is one or more of a reverse osmosis membrane, a cation exchange membrane, an anion exchange membrane, a bipolar membrane, and a non-ion selective porous diaphragm, which can be used alone or in combination, or in combination with a filter cloth.

19. The device according to claim 18, characterized in that The electrolytic cell separator is a reverse osmosis membrane and / or a cation exchange membrane.

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