阅读说明：本技术 一种垃圾渗滤液膜浓缩液减量化及资源化处理系统和方法 (Garbage leachate membrane concentrated solution reduction and recycling treatment system and method ) 是由 黄亚继 戚二兵 袁琦 胡华军 丁守一 樊聪慧 曹彦彦 于 2019-11-27 设计创作，主要内容包括：本发明公开一种垃圾渗滤液膜浓缩液减量化及资源化处理系统和方法,该处理系统包括浸没燃烧蒸发装置、工业盐制取装置和杂盐资源化装置以及废渣处理装置；工业盐制取装置包括以饱和膜浓缩液制取工业盐KCl、NaCl的强制循环蒸发结晶器、以出强制循环蒸发结晶器的母液制取工业盐NaNO<Sub>3</Sub>、Na<Sub>2</Sub>SO<Sub>4</Sub>的闪蒸降温结晶器和硫酸钠蒸发器,杂盐资源化装置包括反应釜,反应釜内投加有浓硫酸,制取工业盐后产生的杂盐进入反应釜中反应制取NaHSO<Sub>4</Sub>、HCl,反应后的废盐进入废渣处理装置成型以便固化填埋。该处理系统通过浸没燃烧蒸发减量处理膜浓缩液的同时实现工业盐的分离,减少盐在环境中的循环并将其资源化,进一步提高了垃圾渗滤液膜浓缩液处理的经济性和环保性。(Hair brushThe treatment system comprises an immersion combustion evaporation device, an industrial salt preparation device, a miscellaneous salt recycling device and a waste residue treatment device; the industrial salt preparation device comprises a forced circulation evaporative crystallizer for preparing industrial salt KCl and NaCl from a saturated membrane concentrated solution, and a forced circulation evaporative crystallizer mother solution for preparing industrial salt NaNO 3 、Na 2 SO 4 The flash evaporation cooling crystallizer and the sodium sulfate evaporator, the mixed salt recycling device comprises a reaction kettle, concentrated sulfuric acid is added into the reaction kettle, and the mixed salt generated after the industrial salt is prepared enters the reaction kettle to react to prepare NaHSO 4 And HCl, and the waste salt after the reaction enters a waste residue treatment device for molding so as to be solidified and buried. The treatment system realizes separation of industrial salt while reducing treatment membrane concentrated solution through submerged combustion evaporation, reduces circulation of salt in the environment and recycles the salt, and further improves the economical efficiency and environmental protection of treatment of the landfill leachate membrane concentrated solution.)

1. A garbage leachate membrane concentrated solution reduction and resource treatment system is characterized by comprising an immersion combustion evaporation device, an industrial salt preparation device and a miscellaneous salt resource device for resource utilization of evaporated saturated membrane concentrated solution, and a waste residue treatment device; the industrial salt preparation device comprises a forced circulation evaporative crystallizer for preparing industrial salt KCl and NaCl from a saturated membrane concentrated solution, and a forced circulation evaporative crystallizer mother solution for preparing industrial salt NaNO₃、Na₂SO₄The flash evaporation cooling crystallizer and the sodium sulfate evaporator are adopted, the mixed salt recycling device comprises a reaction kettle, concentrated sulfuric acid is added into the reaction kettle, and mixed salt generated after the industrial salt is prepared by the flash evaporation cooling crystallizer and the sodium sulfate evaporator enters the reaction kettle to react to prepare NaHSO₄HCl, waste after reactionAnd (4) the salt enters a waste residue treatment device for molding so as to be solidified and buried.

2. The landfill leachate membrane concentrate reduction and resource treatment system of claim 1, wherein the submerged combustion evaporation plant comprises a two-stage SCE unit, the saturated membrane concentrate outlet of the first-stage SCE unit is divided into two paths, one path is connected with the forced circulation evaporation crystallizer, and the other path is connected with the second-stage SCE unit; the secondary SCE device also comprises a mixed salt inlet which is connected with the flash evaporation cooling crystallizer and a mixed salt outlet of the sodium sulfate evaporator.

3. The system for the reduction and recycling of landfill leachate membrane concentrate of claim 2, wherein the miscellaneous salt recycling device further comprises a sedimentation tank, wherein a liquid inlet of the sedimentation tank is connected with the second-stage SCE device, a sedimentation outlet is connected with the reaction kettle, and a clear liquid outlet is connected with the second-stage SCE device.

4. The landfill leachate membrane concentrate reduction and resource treatment system of claim 2, wherein the liquid outlet of the waste residue treatment device is connected to the secondary SCE device, and waste liquid generated in the waste residue treatment process is returned to the secondary SCE device.

5. The system for the reduction and recycling of landfill leachate membrane concentrate of claim 2, wherein the concentration ratio of the first SCE is 5 to 15 times, and the concentration ratio of the second SCE is 15 to 25 times.

6. The landfill leachate membrane concentrate reduction and resource treatment system of claim 1, further comprising a coagulation sedimentation tank and a catalytic oxidizer connected to an inlet of the submerged combustion evaporation device, wherein the coagulation sedimentation tank is used for removing hardness particles, heavy metal particles and impurities in the membrane concentrate, the precipitate out of the coagulation sedimentation tank enters the waste residue treatment device for forming, and the clarified liquid enters the catalytic oxidizer for reaction and reduction of organic matter content.

7. The landfill leachate membrane concentrate reduction and resource treatment system of claim 1, wherein the steam outlet of the submerged combustion evaporation device is connected with the steam inlets of the forced circulation evaporation crystallizer, the flash evaporation cooling crystallizer and the sodium sulfate evaporator respectively, so as to provide steam for the industrial salt preparation process.

8. The landfill leachate membrane concentrate reduction and resource treatment system according to claim 7, further comprising a burner for purifying the non-condensable gas, and a heat exchanger for generating steam, wherein a non-condensable gas inlet of the burner is connected with flue gas outlets of the forced circulation evaporation crystallizer, the flash evaporation cooling crystallizer and the sodium sulfate evaporator, a high-temperature flue gas inlet of the heat exchanger is connected with a high-temperature flue gas outlet of the burner, and a steam outlet of the heat exchanger is connected with steam inlets of the forced circulation evaporation crystallizer, the flash evaporation cooling crystallizer and the sodium sulfate evaporator respectively to provide steam for the industrial salt preparation process.

9. A method for the reduction and recycling of landfill leachate membrane concentrate using the system of claim 1, comprising the steps of:

(1) the nanofiltration and reverse osmosis membrane concentrated solution enters an immersion combustion evaporation device, the membrane concentrated solution evaporated to saturation enters a forced circulation evaporation crystallizer of an industrial salt preparation device, and meanwhile, steam generated in the immersion combustion evaporation process is sent to the industrial salt preparation device;

(2) in a forced circulation evaporation crystallizer, cooling the saturated membrane concentrated solution in a cooling section to separate KCL out, separating NaCL out in an evaporation section, and simultaneously, feeding the mother solution separated out of NaCL into a flash evaporation cooling crystallizer and a sodium sulfate evaporator to respectively prepare NaNO₃And Na₂SO₄The generated mixed salt enters a reaction kettle of a mixed salt recycling device;

(3) in a reaction kettle, mixed salt reacts with concentrated sulfuric acid at high temperature to prepare NaHSO₄Collecting HCl generated in the reaction process; meanwhile, waste salt after high-temperature reaction entersAnd the waste residue treatment device is used for landfill after solidification and molding.

10. The method of landfill leachate membrane concentrate reduction and resource recovery as claimed in claim 9, wherein the submerged combustion evaporation plant comprises a two-stage SCE unit, and the saturated membrane concentrate from the first stage SCE unit is divided into two parts, one part is sent to an industrial salt preparation plant to prepare industrial salt, and the other part is sent to the second stage SCE unit; the mixed salt recycling device also comprises a sedimentation tank, saturated membrane concentrated solution from the first-stage SCE device and mixed salt from the industrial salt preparation device enter a second-stage SCE device, the saturated membrane concentrated solution is concentrated in the second-stage SCE device at high power, the obtained evaporated solution is settled in the sedimentation tank, clarified solution returns to the second-stage SCE device, and the sediment enters a reaction kettle to prepare NaHSO₄(ii) a And waste liquid generated in the solidification and forming process of the waste residue treatment device returns to the secondary SCE device.

Technical Field

The invention relates to a garbage leachate membrane concentrated solution reduction and recycling treatment system and method, and belongs to the technical field of organic high-salt waste liquid treatment.

Background

The existing treatment method for the landfill leachate membrane concentrated solution mainly comprises the following steps: recharging, advanced oxidation, incineration, and the like; although the membrane concentrated solution treated by the recharging method has the advantages of low cost and simple operation, salt and refractory substances are continuously accumulated in the recharging process, so that high-salt leachate enters a treatment system again in the subsequent treatment process, the osmotic pressure is increased, and the service life of the membrane is shortened; the advanced oxidation method has flexible technology selection, but has higher treatment cost and difficult treatment effect reaching the discharge standard; the content of calcium and magnesium ions in the membrane concentrated solution is high, a hearth of the membrane concentrated solution treated by an incineration method is easy to scale and corrode, and organic gas generated in the incineration process pollutes the environment.

Aiming at the difficult problem of treating the membrane concentrated solution, scientific researchers provide a technical scheme for treating the membrane concentrated solution by evaporation decrement, wherein a small part of volatile organic compounds and ammonia can enter the condensed liquid in the evaporation process, and inorganic substances, macromolecular organic substances and heavy metal salts are remained in the evaporated liquid; the evaporation method can concentrate the membrane concentrated solution to more than ten times, and the membrane concentrated solution after the decrement treatment is shaped by filter pressing and sent to a landfill site or burnt in a furnace to prevent the circulation of salt. The energy required by immersion and evaporation can be derived from landfill gas generated by a refuse landfill, and the landfill gas is combusted to generate high-temperature flue gas evaporation membrane concentrated solution, so that the aim of treating waste by waste is fulfilled; the high-temperature flue gas discharged in industrial production can be fully utilized, and the discharge of harmful substances such as fly ash and the like can be reduced while the membrane concentrated solution is subjected to evaporation decrement treatment. The immersion evaporation method has the outstanding characteristics that: high-temperature gas and liquid directly exchange heat, so that the utilization efficiency of energy is improved, and meanwhile, no interlayer heat transfer is performed, and the risks of scaling and corrosion of a heating surface are avoided; because the partial pressure of water vapor is lower in the evaporation process, the liquid can be boiled at a lower temperature, the effect of reduced pressure evaporation under the normal pressure condition is realized, and the reduced pressure evaporation is favorable for removing volatile organic compounds.

However, the concentrated solution after evaporation has high concentration ratio and high salt content, so that a large amount of landfill is not beneficial to environmental protection on one hand, and is also waste of resources on the other hand.

Based on this, it is urgently needed to explore how to realize the further resource utilization of the concentrated solution.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the problems that the traditional treatment method of the membrane concentrated solution in the prior art is not ideal in effect, and reduction and recycling are insufficient in the treatment process of the submerged evaporation method, the invention provides a reduction and recycling treatment system for the garbage leachate membrane concentrated solution, and a method for carrying out reduction and recycling treatment on the membrane concentrated solution by using the system.

The technical scheme is as follows: the inventionThe garbage leachate membrane concentrated solution reduction and recycling treatment system comprises an immersion combustion evaporation device, an industrial salt preparation device and a miscellaneous salt recycling device for recycling evaporated saturated membrane concentrated solution, and a waste residue treatment device; the industrial salt preparation device comprises a forced circulation evaporative crystallizer for preparing industrial salt KCl and NaCl from a saturated membrane concentrated solution, and a forced circulation evaporative crystallizer mother solution for preparing industrial salt NaNO₃、Na₂SO₄The flash evaporation cooling crystallizer and the sodium sulfate evaporator are adopted, the mixed salt recycling device comprises a reaction kettle, concentrated sulfuric acid is added into the reaction kettle, and mixed salt generated after the industrial salt is prepared by the flash evaporation cooling crystallizer and the sodium sulfate evaporator enters the reaction kettle to react to prepare NaHSO₄And HCl, and the waste salt after the reaction enters a waste residue treatment device for molding so as to be solidified and buried.

Preferably, the submerged combustion evaporation device comprises two SCE devices, a saturated membrane concentrated solution outlet of the first SCE device is divided into two paths, one path is connected with the forced circulation evaporation crystallizer, and the other path is connected with the second SCE device; the secondary SCE device also comprises a mixed salt inlet which is connected with the flash evaporation cooling crystallizer and a mixed salt outlet of the sodium sulfate evaporator. Wherein, the concentration multiplying power of the first-stage SCE device can be 5-15 times, and the concentration multiplying power of the second-stage SCE device can be 15-25 times.

Further, miscellaneous salt resourceful device still includes the sedimentation tank, and the inlet and the second grade SCE ware of sedimentation tank are connected, and the deposit exit linkage reation kettle, clarified liquid exit linkage second grade SCE ware simultaneously. Furthermore, a liquid outlet of the waste residue treatment device is also connected with the secondary SCE device, and waste liquid generated in the waste residue treatment process returns to the secondary SCE device.

Wherein, the number of the reaction kettles can be two, concentrated sulfuric acid is added into the first reaction kettle, and NaHSO is prepared by reaction₄And the reaction mother liquor enters a second reaction kettle to be concentrated and then returns to the first reaction kettle, and HCL is also generated in the second reaction kettle.

The treatment system can also comprise a coagulation sedimentation tank and a catalytic oxidation device which are connected with the inlet of the submerged combustion evaporation device, wherein the coagulation sedimentation tank is used for removing hardness particles, heavy metal particles and impurities in the membrane concentrated solution, the sediment discharged from the coagulation sedimentation tank enters the waste residue treatment device for forming, and the clarified solution enters the catalytic oxidation device for reaction and reducing the content of organic matters.

Preferably, the steam required in the industrial salt preparation process can be steam generated in the evaporation process of the submerged combustion evaporation device; the steam outlet of the submerged combustion evaporation device can be respectively connected with the steam inlets of the forced circulation evaporation crystallizer, the flash evaporation cooling crystallizer and the sodium sulfate evaporator, so that steam is provided for the industrial salt preparation process.

Preferably, the treatment system further comprises a burner for purifying the non-condensable gas and a heat exchanger for generating steam, wherein a non-condensable gas inlet of the burner is connected with flue gas outlets of the forced circulation evaporation crystallizer, the flash evaporation cooling crystallizer and the sodium sulfate evaporator, a high-temperature flue gas inlet of the heat exchanger is connected with a high-temperature flue gas outlet of the burner, and a steam outlet is respectively connected with steam inlets of the forced circulation evaporation crystallizer, the flash evaporation cooling crystallizer and the sodium sulfate evaporator to provide steam for the industrial salt preparation process. The steam generated in the evaporation process of the submerged combustion evaporation device contains organic matters, the organic matters are sent into the industrial salt preparation device along with the steam, but are not condensed along with the steam after heat exchange in the industrial salt preparation device, namely, the non-condensable gas is sent into the combustor to be incinerated and purified, the high-temperature flue gas generated by combustion is sent into the heat exchanger to exchange heat, and the generated steam can also be provided for the industrial salt preparation process.

The method for performing the reduction and resource treatment on the landfill leachate membrane concentrated solution by using the system comprises the following steps:

(1) the nanofiltration and reverse osmosis membrane concentrated solution enters an immersion combustion evaporation device, the membrane concentrated solution evaporated to saturation enters a forced circulation evaporation crystallizer of an industrial salt preparation device, and meanwhile, steam generated in the immersion combustion evaporation process is sent to the industrial salt preparation device;

(2) in a forced circulation evaporation crystallizer, cooling the saturated membrane concentrated solution in a cooling section to separate KCL out, separating NaCL out in an evaporation section, and simultaneously, feeding the mother solution separated out of NaCL into a flash evaporation cooling crystallizer and a sodium sulfate evaporator to respectively prepare NaNO₃And Na₂SO₄The generated mixed salt enters a reaction kettle of a mixed salt recycling device;

(3) in a reaction kettle, mixed salt reacts with concentrated sulfuric acid at high temperature to prepare NaHSO₄Collecting HCl generated in the reaction process; meanwhile, the waste salt after the high-temperature reaction enters a waste residue treatment device, and is buried after being solidified and formed.

Preferably, the submerged combustion evaporation device comprises a two-stage SCE device, saturated membrane concentrated solution of the first-stage SCE device is divided into two paths, one path is sent into the industrial salt preparation device to prepare industrial salt, and the other path is sent into the second-stage SCE device; the mixed salt recycling device also comprises a sedimentation tank, saturated membrane concentrated solution from the first-stage SCE device and mixed salt from the industrial salt preparation device enter the second-stage SCE device firstly, are concentrated in the second-stage SCE device at high power, the obtained evaporated solution is settled in the sedimentation tank, clarified solution returns to the second-stage SCE device, and the sediment enters the reaction kettle to prepare NaHSO₄(ii) a And waste liquid generated in the solidification and forming process of the waste residue treatment device returns to the secondary SCE device.

The working principle is as follows: the membrane concentrated solution enters an immersion combustion evaporation device to be evaporated to saturation and then enters a forced circulation evaporation crystallizer, the solubility of NaCl in the forced circulation evaporation crystallizer is very small when the temperature changes due to the difference of KCl and NaCl solubilities, the solubility of KCl is quite obvious, the saturated solution is cooled down and cooled to separate out KCl, the centrifugal mother solution returns to an evaporation system, and NaCl is separated out in an evaporation working section when the proportion of Na and K in the mother solution reaches a certain concentration; mother liquor separated out NaCl enters a flash evaporation cooling crystallizer and a sodium sulfate evaporator to respectively prepare NaNO₃、Na₂SO₄The mother liquor after freezing crystallization returns to a sodium sulfate evaporator, the mixed salt enters a mixed salt recycling device, and the mixed salt after flash evaporation cooling crystallizer also enters the mixed salt recycling device; adding concentrated sulfuric acid into a reaction kettle, after high-temperature reaction, cooling and crystallizing a product, and then using saturated NaHSO₄Washing to prepare industrial-grade NaHSO₄Collecting HCl generated in the reaction kettle; and solidifying and forming the reacted waste salt by a waste residue treatment device and then burying the waste salt.

Has the advantages that: compared with the prior art, the invention has the advantages that: the garbage leachate membrane concentrated solution reduction and recycling treatment system solves the problems of insufficient reduction and recycling in the garbage leachate treatment process in the prior art, realizes separation of industrial salt while carrying out reduction treatment on the membrane concentrated solution through immersion combustion and evaporation, reduces the circulation of the salt in the environment and recycles the salt, and further improves the economy and the environmental protection of the garbage leachate membrane concentrated solution treatment.

Drawings

Fig. 1 is a flow chart of a landfill leachate membrane concentrated solution reduction and recycling treatment system of the present invention, wherein an immersion combustion evaporation apparatus is provided in two stages.

Detailed Description

The technical scheme of the invention is further explained by combining the attached drawings.

The invention relates to a garbage leachate membrane concentrated solution reduction and recycling treatment system which mainly comprises an immersion combustion evaporation (SCE) device, an industrial salt preparation device, a miscellaneous salt recycling device and a waste residue treatment device.

As shown in fig. 1, the industrial salt preparation device comprises a forced circulation evaporation crystallizer 5, a flash evaporation cooling crystallizer 6 and a sodium sulfate evaporator 7, the membrane concentrated solution evaporated to saturation in the submerged combustion evaporation device is used for preparing industrial salts KCl and NaCl in the forced circulation evaporation crystallizer 5, when the temperature changes, the solubility change of NaCl is very small, but the solubility change of KCl is quite obvious, the saturated solution is cooled and cooled to separate out KCl, the centrifugal mother liquor returns to the evaporation system, and when the proportion of Na and K in the mother liquor reaches a certain concentration, NaCl is separated out in the evaporation section; mother liquor separated out NaCl enters a flash evaporation cooling crystallizer 6 and a sodium sulfate evaporator 7 to prepare industrial salt NaNO respectively₃、Na₂SO₄(ii) a And the miscellaneous salt generated in the process of preparing the industrial salt by the flash evaporation cooling crystallizer 6 and the sodium sulfate evaporator 7 enters a miscellaneous salt recycling device.

The mixed salt recycling device comprises a reaction kettle 10, concentrated sulfuric acid is added into the reaction kettle 10, the mixed salt enters the reaction kettle 10 and reacts with the concentrated sulfuric acid at high temperature to prepare industrial salt NaHSO₄And HCl generated in the reaction kettle can be collected. Waste salt after reaction entersAnd the waste residue treatment device is formed so as to be solidified and buried. The number of the reaction kettles can be two, concentrated sulfuric acid is added into the reaction kettle 10, and the NaHSO is prepared from reaction products₄Meanwhile, reaction mother liquor enters the reaction kettle 11 to be concentrated and then returns to the reaction kettle 10, HCL is generated in both the reaction kettles, and the HCL can be collected and recycled.

Preparation of NaHSO₄The waste salt after reaction enters a waste residue treatment device 4 for solidification and forming so as to be convenient for subsequent landfill; the waste residue treatment apparatus 4 may be a filter press.

The treatment system of the invention also comprises a coagulation sedimentation tank 1 and a catalytic oxidizer 2, wherein the coagulation sedimentation tank 1, the catalytic oxidizer 2 and the submerged combustion evaporation device are sequentially connected, CaO, MgO, PAC, PAM and NaCO are added into the coagulation sedimentation tank 1₃Coagulant and coagulant aid can remove hardness ions, heavy metal ions and impurities in the membrane concentrated solution; specifically, the addition of CaO and MgO can be combined with active silicic acid in the membrane concentrated solution to form calcium silicate and magnesium silicate precipitates, and the addition of CaO can form Ca in water²⁺And OH^-，OH^-Is easy to combine with heavy metal ions to form heavy metal hydroxide precipitate, Ca²⁺Can also be introduced with CO₃ ^2-、SO₄ ^2-Insoluble salt is generated by the reaction and precipitated, and meanwhile, Ca0 and MgO can also be used as coagulant aids, so that the collision chance of suspended particles is increased, larger floc is easier to form, and colloid and suspended matters in the water body are adsorbed and coated while the precipitate is precipitated; the polyaluminium chloride (PAC) flocculant is subjected to chemical reactions such as electrolysis, hydrolysis and the like in a water body, and then destabilized suspended particles, organic pollutants, heavy metal ion sediments and the like are adsorbed and combined into a large flocculating constituent through adsorption bridging and net capturing and sweeping actions such as an organic polymer flocculant Polyacrylamide (PAM), and the like, and the chromaticity and the turbidity of the water body are reduced simultaneously due to the precipitation under the action of gravity; NaCO is added₃Is used for removing excessive Ca which can enter in the process of adding CaO²⁺Ions, reducing the hardness of the solution, and Na added at the same time⁺The ions are separated as product during the salt separation process. The sedimentation outlet of the coagulation sedimentation tank 1 is connected with the waste residue treatment device 4, the sediment enters the waste residue treatment device 4 for solidification and forming, and the clear liquid enters the catalytic oxygenReacting in the chemical reactor 2 to reduce the organic content in the membrane concentrate. The catalytic oxidizer 2 can adopt a multiphase eutectic catalytic oxidizer, organically combines a micro-nano hydrodynamic cavitation technology, an ozone hydroxylation technology and a multi-component cocrystallization catalysis technology, has incomparable strong oxidizability with other technologies, is particularly suitable for treatment and advanced treatment of difficult biochemical industrial wastewater, has obvious deep decolorization effect, reduces the organic matter content of a treated membrane concentrated solution, reduces the pollution emission in the subsequent submerged combustion evaporation process, and improves the purity in the industrial salt preparation process.

In the industrial salt preparation process, the forced circulation evaporation crystallizer 5, the flash evaporation cooling crystallizer 6 and the sodium sulfate evaporator 7 need steam heat sources when working, the part of the steam heat sources can be steam generated in the evaporation process of the submerged combustion evaporation device, and a steam outlet of the submerged combustion evaporation device is respectively connected with steam inlets of the forced circulation evaporation crystallizer 5, the flash evaporation cooling crystallizer 6 and the sodium sulfate evaporator 7, so that steam can be provided for the industrial salt preparation process.

The steam generated in the evaporation process of the submerged combustion evaporation device contains organic matters, the organic matters are sent into the industrial salt preparation device along with the steam, but the heat exchange of the steam in the forced circulation evaporation crystallizer 5, the flash evaporation cooling crystallizer 6 and the sodium sulfate evaporator 7 is not carried out and then the steam is condensed, namely, the non-condensable gas, in order to treat the part of the organic gas which pollutes the environment, the treatment system of the invention can also comprise a combustor 12 and a heat exchanger 13, the non-condensable gas is sent to the combustor 12 for incineration and purification, meanwhile, the high-temperature flue gas inlet of the heat exchanger 13 is connected with the high-temperature flue gas outlet of the combustor 12, and the steam outlet of the boiler is respectively connected with the steam inlets of the forced circulation evaporation crystallizer 5, the flash evaporation cooling crystallizer 6 and the sodium sulfate evaporator 7, so that high-temperature flue gas generated by the combustor 12 enters the heat exchanger 13 for heat exchange to generate steam, thereby providing steam for the industrial salt preparation process. For further resource utilization, the raw material gas required by the submerged combustion evaporation plant and the combustor 12 can adopt combustible gas such as landfill gas/anaerobic biogas and the like.

The method for performing the reduction and resource treatment on the landfill leachate membrane concentrated solution by adopting the system comprises the following steps:

(1) after the concentrated solution of the nanofiltration membrane and the reverse osmosis membrane is treated by a coagulating sedimentation tank 1, the precipitate enters a waste residue treatment device 4, clear solution enters a catalytic oxidation device 2 to reduce the content of organic matters, then enters an immersion combustion evaporation device for evaporation, the membrane concentrated solution which is evaporated to saturation enters a forced circulation evaporation crystallizer 5 of an industrial salt preparation device, and meanwhile, steam generated in the immersion combustion evaporation process is sent to the industrial salt preparation device;

(2) in a forced circulation evaporation crystallizer 5, cooling the saturated membrane concentrated solution in a cooling section to separate KCL out, separating NaCL out in an evaporation section, and simultaneously, respectively preparing NaNO in mother liquor separated out of the NaCL into a flash evaporation cooling crystallizer 6 and a sodium sulfate evaporator 7₃And Na₂SO₄The generated mixed salt enters a reaction kettle 10 of a mixed salt recycling device;

(3) in a reaction kettle 10, the mixed salt reacts with concentrated sulfuric acid at high temperature to prepare NaHSO₄Collecting HCl generated in the reaction process; meanwhile, the waste salt after the high-temperature reaction enters a waste residue treatment device 4, and is solidified and molded together with the precipitate discharged from the coagulation sedimentation tank 1 and then buried.

In the treatment system, in order to enhance the reduction degree of the submerged combustion evaporation device and adjust the salt yield, the SCE device can be provided with two stages, as shown in figure 1, a first-stage SCE device 3 and a second-stage SCE device 8 are respectively arranged, the concentration multiplying power of the first-stage SCE device 3 is generally set to be 5-15 times, and the concentration multiplying power of the second-stage SCE device 8 is set to be 15-25 times; in order to adjust the load of the first-stage SCE device and the second-stage SCE device, a channel is arranged between the first-stage SCE device and the second-stage SCE device, after the membrane concentration in the first-stage SCE device 3 is concentrated to saturation, part of saturated membrane concentrated solution can enter the second-stage SCE device 8.

In the two-stage SCE device, a secondary SCE device 8 is provided with a mixed salt inlet which is connected with a mixed salt outlet of a flash evaporation cooling crystallizer 6 and a sodium sulfate evaporator 7; after the membrane concentrated solution in the first-stage SCE device 3 is recycled by the industrial salt preparation device, the generated mixed salt is sent into the second-stage SCE device 8, and enters the mixed salt recycling device after being concentrated by high power. Meanwhile, a sedimentation tank 9 is arranged in front of a reaction kettle 10 in the mixed salt recycling device, a liquid inlet of the sedimentation tank 9 is connected with a second-stage SCE device 8, a sedimentation outlet of the sedimentation tank 9 is connected with the reaction kettle 10, and a clear liquid outlet is connected with the second-stage SCE device 8. In addition, the liquid outlet of the waste residue treatment device 4 is also connected with the secondary SCE device 8, and waste liquid generated in the waste residue treatment process returns to the secondary SCE device 8. Namely, part of low concentration rate evaporated liquor, miscellaneous salt and waste residue of the first-stage SCE device 3 are treated by the filter pressing waste liquor of the device 4 and clear liquor of the sedimentation tank 9 enter the second-stage SCE device 8 for high concentration.

The membrane concentrated solution reduction and recycling treatment method based on the two-stage SCE device comprises the following steps:

(1) the nanofiltration and reverse osmosis membrane concentrated solution firstly enters a coagulation sedimentation tank 1, and CaO, MgO, PAC, PAM and NaCO are added₃Removing hardness ions, heavy metal ions and impurities from the coagulant and the coagulant aid through flocculation and precipitation, enabling the generated precipitate to enter a waste residue treatment device 4, enabling clear liquid to enter a catalytic oxidizer 2 for deep treatment, and reducing the organic matter content of the treated membrane concentrated liquid;

(2) the membrane concentrated solution from the catalytic oxidizer 2 enters a first-stage SCE device 3, after the membrane concentration in the first-stage SCE device 3 is concentrated to saturation, in order to improve the reduction degree and adjust the salt yield, part of the concentrated solution enters a second-stage SCE device 8; the membrane concentrated solution evaporated to saturation in the first-stage SCE device 3 enters an industrial salt preparation device, in a forced circulation evaporation crystallizer 5, when the temperature changes, the solubility change of NaCl is very small, the solubility change of KCl is quite obvious, the saturated solution is cooled down and separated out KCl, the centrifugal mother solution returns to an evaporation system, and when the proportion of Na and K in the mother solution reaches a certain concentration, NaCl is separated out in an evaporation working section; mother liquor separated out NaCl enters a flash evaporation cooling crystallizer 6 and a sodium sulfate evaporator 7 to prepare NaNO₃、Na₂SO₄The mother liquor after freezing and crystallization returns to a sodium sulfate evaporator 7, and the miscellaneous salt enters a secondary SCE device 8;

(3) in a second-stage SCE device 8, the membrane concentrated solution is evaporated to a part with higher concentration ratio and is salted out, the clear solution returns to the second-stage SCE device 8 after passing through a sedimentation tank 9, the precipitate enters a reaction kettle 10, concentrated sulfuric acid is added into the reaction kettle 10 for high-temperature reaction, the product is diluted by distilled water and then is cooled and crystallized, and the product is saturated NaHSO₄Washing to prepare industrial-grade NaHSO₄(ii) a The mother liquor enters a reaction kettle 11 to be concentrated and then returns to a reaction kettle 10; collection reaction vessel 10 andHCl generated in the reactor 11;

(4) preparation of NaHSO from reaction kettle 10₄And (3) allowing the waste salt and the precipitate generated in the coagulation sedimentation tank 1 to enter a waste residue treatment device 4 for solidification and forming, allowing the press filtrate to enter a secondary SCE (secondary sludge activated sludge) device 8, and solidifying and burying the formed waste residue.

In the treatment process, part of the steam required by the industrial salt production device comes from the steam generated in the evaporation process of the SCE (sodium chloride) devices 3 and 8, and the other part of the steam comes from the steam generated by heating the water in the heat exchanger 13 by the high-temperature flue gas from the combustor 12; steam generated in the evaporation process of the SCE devices 3 and 8 is sent into the industrial salt preparation device for heat exchange and condensation, and then non-condensable gas enters the combustor 12 for incineration and removal of pollutants and odor.

The treatment system mainly treats the garbage percolation membrane concentrated solution after nanofiltration and reverse osmosis treatment, wherein the nanofiltration has a good effect of intercepting divalent salts and macromolecular organic matters, and the reverse osmosis has a good effect of intercepting monovalent ions and micromolecular organic matters. The treatment system has high practical value and economic value for treating the garbage leachate membrane concentrated solution, and has good reduction and recycling effects on other organic waste liquids.