CN115710062A - Leachate pretreatment process for household garbage landfill - Google Patents
Leachate pretreatment process for household garbage landfill Download PDFInfo
- Publication number
- CN115710062A CN115710062A CN202211361255.1A CN202211361255A CN115710062A CN 115710062 A CN115710062 A CN 115710062A CN 202211361255 A CN202211361255 A CN 202211361255A CN 115710062 A CN115710062 A CN 115710062A
- Authority
- CN
- China
- Prior art keywords
- vapor
- treatment
- mvr
- leachate
- water
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Abstract
The invention discloses a leachate pretreatment process for a domestic garbage landfill, which is characterized by comprising the following steps of: s1, preprocessing; s2, adjusting the pH value; s3, concentrating by an MVR evaporator; s4, steam alkali washing; s5, performing low-temperature forced circulation concentration on MVR; s6, performing secondary RO treatment; s7, deep processing; and S8, solidifying the concentrated solution. The invention can effectively remove suspended matters in the landfill leachate, effectively reduce the scaling speed of the evaporator and reduce ammonia nitrogen in evaporation produced water.
Description
Technical Field
The invention relates to the technical field of sewage treatment, in particular to a leachate pretreatment process for a domestic garbage landfill.
Background
The landfill leachate is sewage generated by the influence of external factors through complex physical, chemical and biochemical actions of garbage in the sanitary landfill process. Landfill leachate is classified into two categories according to its landfill age: one is early percolate, the landfill time is less than 5 years, and the water quality of the produced percolate is characterized by lower pH value, higher COD and BOD5 concentration, higher BOD5/COD ratio and higher concentration of various heavy metals; the other is old percolate, the landfill time is more than 5 years, and the main water quality characteristics of the generated percolate are that the pH value is close to neutral, the COD and the BOD5 concentration are lower, the BOD5/COD ratio is lower, the ammonia nitrogen concentration is higher, and the heavy metal concentration begins to decrease.
At present, most landfill sites adopt a combined process of pretreatment (coagulating sedimentation, ammonia nitrogen stripping, chemical oxidation, hydrolytic acidification and the like), biological treatment (anaerobic treatment, anoxic treatment, aerobic treatment and the like), physicochemical advanced treatment (adsorption, membrane separation, advanced oxidation and the like), and effluent is directly discharged or brought into a sewage pipe network. The pretreatment method mainly comprises a physical method, a chemical method, a biological method and the like, and the process mainly aims to remove ammonia nitrogen or inorganic impurities or improve the biodegradability of the percolate.
Chinese patent with patent application number CN201510092161.2 discloses a treatment process of landfill leachate, coagulation air flotation or precipitation and ammonia nitrogen stripping are adopted as pretreatment, the ammonia nitrogen removal effect of the pretreatment process is good, inorganic impurities can be effectively removed, but the process has the problems of large occupied area, incapability of effectively inhibiting toxic and harmful substances and the like.
Chinese patent No. CN201310720198.6 discloses a treatment method for early stage landfill leachate, which comprises a biological treatment section comprising an anaerobic reactor and an integrated denitrification reactor, and an integrated iron-carbon fenton reactor, a chemical oxidation treatment section, a coagulating sedimentation, a filtration treatment, and the like, wherein the treatment process uses an anaerobic reactor as a pretreatment process, and degrades most organic substances in the early stage landfill leachate into small molecular organic substances by using the degradation of anaerobic microorganisms.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a leachate pretreatment process for a domestic garbage landfill, which can effectively remove suspended matters in landfill leachate, effectively reduce the scaling speed of an evaporator and reduce ammonia nitrogen in evaporation produced water.
In order to achieve the purpose, the invention adopts the following scheme:
a leachate pretreatment process for a domestic garbage landfill is characterized by comprising the following steps:
s1, pretreatment
Performing two-stage filtration on the landfill leachate by adopting a fiber filter and a core filter to reduce the content of suspended matters by 180-250mg/L;
s2, adjusting the pH value
The garbage percolate from which suspended matters are removed is firstly lifted to a raw liquid tank by a pump, concentrated sulfuric acid is added into the raw liquid tank by a metering pump, and stirring is carried out simultaneously, so that the pH is adjusted to 5.5-6.5;
s3, concentrating by an MVR evaporator
Pumping the landfill leachate after pH adjustment into an MVR evaporator, evaporating water in the landfill leachate to form water vapor, feeding the water vapor into an alkaline washing system, and collecting residual concentrated solution of the landfill leachate into a hot well at the lower part of the evaporator;
s4, steam alkali washing
Washing water vapor generated in the MVR evaporation treatment process by using high-temperature alkali liquor to enable COD in the vapor to react with the high-temperature alkali liquor and be trapped in the alkali liquor, so that the vapor is purified, the COD in the vapor distilled water is reduced, and the load of subsequent membrane advanced treatment is reduced;
s5, low-temperature forced circulation concentration of MVR
Controlling the garbage percolation concentrated solution generated in the MVR evaporation treatment process to enter an MVR low-temperature forced circulation concentration evaporator for treatment, sending the obtained concentrated solution to a concentrated solution solidification treatment device, and sending the obtained distilled water to a secondary RO treatment device for treatment;
s6, two-stage RO treatment
Treating the distilled water after MVR low-temperature forced circulation concentration and the distilled water generated by the MVR evaporator by adopting a two-stage roll type RO, and reducing the content of ammonia nitrogen in the distilled water;
s7, deep processing
Performing advanced treatment on the effluent after the two-stage roll type RO treatment by adopting an ion exchange system;
s8, solidifying the concentrated solution
Pumping concentrated solution generated in the MVR evaporation treatment process into a mixing stirrer by a pump, adding a stabilizer, fully stirring and mixing, and conveying the slurry to a mold through a conveyor to be solidified and molded.
As another improvement of the leachate pretreatment process for the domestic garbage landfill, the method further comprises the following steps of S9: the non-condensable gas generated in the MVR evaporation treatment process and the odor generated in the pH value adjusting process are collected in the tank body and conveyed to the acid-base washing tower through the fan for treatment.
As another improvement of the leachate pretreatment process for the domestic waste landfill, the acid-base washing tower adopts sulfuric acid and NaOH solution as detergents.
As another improvement of the leachate pretreatment process for the household garbage landfill, the stabilizing agent comprises lime, cement and a chelating agent.
As another improvement of the leachate pretreatment process for the domestic garbage landfill, the MVR evaporator comprises a shell, a heat exchange tube set is arranged in the shell, two ends of the heat exchange tube set extend out of the shell, a steam collecting part is arranged on one side of the shell, an inlet end of the heat exchange tube set is communicated with the steam collecting part, a liquid collecting part is arranged on the other side of the shell, an outlet end of the heat exchange tube set is communicated with the liquid collecting part, a spray pipe is arranged in the shell on the upper side of the heat exchange tube set, the spray pipe is communicated with a water inlet pipe, a steam outlet is arranged on the upper part of the shell, the steam outlet is connected with a steam inlet of a steam compressor, a steam outlet of the steam compressor is connected with the steam collecting part, a demister is arranged in the steam outlet, a liquid outlet at the lower end of the liquid collecting part is connected with a condensate liquid outlet pipe, a heat well is arranged in the middle of the lower end of the shell, the heat well is connected with a filter, a liquid outlet end of the filter is connected with a drain pipe, a liquid outlet end of the filter is communicated with the spray pipe through a circulating pump, and a drain pipe.
As another improvement of the leachate pretreatment process for the household garbage landfill, the step S1 and the step S2 are carried out in a pretreatment device, wherein the pretreatment device comprises a base, a support, a shell and a raw liquid tank, the upper side of the base is connected with the support, the upper part of the support is connected with the shell, the shell is provided with the raw liquid tank for bearing leachate, the pretreatment device further comprises the raw liquid pump, a liquid pump and a first conveying pipe, the lower part of the raw liquid tank is provided with the raw liquid pump communicated with the raw liquid tank, the first conveying pipe is provided with two pipes in the upper and lower directions, one end of the first conveying pipe above the first conveying pipe is communicated with the raw liquid tank, and the other end of the first conveying pipe above the first conveying pipe is communicated with one end of the other first conveying pipe.
As another improvement of the leachate pretreatment process for the household garbage landfill, the leachate pretreatment process further comprises a fiber filter and a core type filter, wherein the fiber filter and the core type filter communicated with the fiber filter are installed on the upper side of the base, and the core type filter is communicated with the first conveying pipe below the base.
As another improvement of the leachate pretreatment process for the household garbage landfill, the leachate pretreatment process further comprises a metering pump, and the upper side of the right part of the shell is provided with the metering pump communicated with the liquid storage tank.
The improved leachate pre-treating process for household garbage burying field includes one support plate, one liquid storage tank connected to the back side of the casing, and one second conveying pipe connected between the liquid storage tank and the metering pump.
The invention further provides another improvement of the leachate pretreatment process for the household garbage landfill, which comprises a mounting rack, a motor and a rotating shaft, wherein the motor is mounted on the left side of the raw liquid tank through the mounting rack, the rotating shaft which rotatably penetrates through the raw liquid tank is connected to an output shaft of the motor, and the leachate pretreatment process further comprises fan blades, and the fan blades are connected to the rotating shaft.
In summary, compared with the prior art, the invention has the beneficial effects that:
the invention can effectively remove suspended matters in the landfill leachate, effectively reduce the scaling speed of the evaporator and reduce ammonia nitrogen in evaporation produced water.
Drawings
FIG. 1 is a schematic view of the process of the present invention.
FIG. 2 is a schematic view of the MVR evaporator according to the present invention.
FIG. 3 is a schematic perspective view of a first embodiment of the pretreatment apparatus of the present invention.
FIG. 4 is a cross-sectional view of a pretreatment device of the present invention.
FIG. 5 is a schematic perspective view of a second embodiment of the pretreatment apparatus of the present invention.
Detailed Description
The above and further features and advantages of the present invention are described in more detail below with reference to the accompanying drawings.
Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and do not limit the scope of the present invention.
It should be noted that in the description of the present invention, the terms of direction or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, which are only for convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
Furthermore, it should be noted that, in the description of the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Example 1
A leachate pretreatment process for a domestic garbage landfill comprises the following steps:
s1, pretreatment
Performing two-stage filtration on the landfill leachate by adopting a fiber filter and a core filter to reduce the content of suspended matters by 180-250mg/L;
the landfill leachate contains higher-content suspended matters, and the subsequent treatment units need to be pretreated to reduce the suspended matters in order to ensure the stable operation of the subsequent treatment units.
S2, adjusting the pH value
The garbage percolate from which suspended matters are removed is firstly lifted to a raw liquid tank by a pump, and concentrated sulfuric acid is added into the raw liquid tank by a metering pump and stirred simultaneously; in the process step, concentrated sulfuric acid is added, so that the scaling speed of an evaporator can be effectively reduced, the ammonia nitrogen in evaporation produced water can be reduced, the pH of the landfill leachate in the raw liquid tank is adjusted to 5.5-6.5 by the concentrated sulfuric acid, most of the ammonia nitrogen in the concentrated solution exists in the form of ammonium ions, and the ammonia nitrogen is prevented from evaporating out along with water vapor.
S3, concentrating by an MVR evaporator
Pumping the landfill leachate after pH adjustment into an MVR evaporator, evaporating water in the landfill leachate to form water vapor, feeding the water vapor into an alkaline washing system, and collecting residual concentrated solution of the landfill leachate in a hot well at the lower part of the MVR evaporator;
the preheated landfill leachate or/and concentrated solution stored in a hot well at the bottom of the MVR evaporator are/is mixed by a circulating pump and then pumped into a spraying pipe at the upper part of the MVR evaporator, the landfill leachate or the mixed solution is uniformly sprayed on the outer surface of a heat exchange pipe bundle to form a liquid film, the liquid film is heated, boiled and evaporated in the process of flowing downwards from the heat exchange pipe bundle, and the residual part, namely the concentrated solution, is collected in the hot well at the lower part of the evaporator.
The evaporation takes place at the tube bank surface, the regenerated steam of formation, through efficient vapor compressor with the pressure and the temperature improvement of steam, form the inside that saturated steam got into heat exchange tube bank, on the one hand give the incoming water film of tube bank surface with heat energy transfer in order to form the evaporation, on the other hand, this saturated steam is cooled off in the tube bank, distilled water forms and is collected the water cavity in the pipe, then flash distillation to a degasser, the organic gas that probably recondenses to distilled water can very effectually be eliminated in the flash distillation, defogging net can make the quality of distilled water better.
The concentrated solution after continuous concentration is collected at the bottom of the hot well and pumped out to a separation chamber of the forced circulation evaporation system by a concentrated solution pump.
The invention utilizes the horizontal tube falling film MVR evaporator to perform concentration decrement firstly, reduces the processing amount of the forced circulation evaporator, has low energy consumption and reduces the operation cost integrally.
S4, steam alkali washing
Washing water vapor generated in the MVR evaporation treatment process by using high-temperature alkali liquor to enable COD in the vapor to react with the high-temperature alkali liquor and be trapped in the alkali liquor, so that the vapor is purified, the COD in the vapor distilled water is reduced, and the load of subsequent membrane advanced treatment is reduced;
certain COD is carried in the high-temperature steam generated by evaporation, most of the part of the COD belongs to organic acid, and the high-temperature liquid caustic soda is used for washing the high-temperature liquid caustic soda in the process step, so that more than 99% of the COD in the steam is intercepted in the liquid caustic soda through the reaction with the high-temperature liquid caustic soda, thereby purifying the steam, and reducing the COD in the steam distilled water and the load of deep membrane treatment.
S5, low-temperature forced circulation concentration of MVR
Controlling the garbage percolation concentrated solution generated in the MVR evaporation treatment process to enter an MVR low-temperature forced circulation concentration evaporator for treatment, sending the obtained concentrated solution to a concentrated solution solidification treatment device, and sending the obtained distilled water to a secondary RO treatment device for treatment;
s6, two-stage RO treatment
Treating distilled water after MVR low-temperature forced circulation concentration and distilled water generated by an MVR evaporator by adopting two-stage roll type RO, and reducing the content of ammonia nitrogen in the distilled water;
the RO membrane, also called reverse osmosis membrane, applies pressure to raw water by machine, so that water in the raw water can permeate the RO membrane, and retains fine impurities, excessive inorganic salts, organic matters, heavy metal ions, bacteria, viruses, pesticides, trichloromethane waste water and other harmful substances in the raw water, and discharges the harmful foreign matters and salt through continuously discharged concentrated water.
A reverse osmosis membrane is a membrane selective to a substance to be permeated is called a semipermeable membrane, and a membrane permeable only to a solvent and impermeable to a solute is generally called an ideal semipermeable membrane. When the same volume of dilute solution (e.g., fresh water) and concentrated solution (e.g., saline) is placed on each side of the semi-permeable membrane, the solvent in the dilute solution will naturally flow through the semi-permeable membrane spontaneously to the concentrated solution side, a phenomenon known as osmosis. When the osmosis reaches the balance, the liquid level of the concentrated solution side is higher than the liquid level of the dilute solution by a certain height, namely, a pressure difference is formed, and the pressure difference is the osmotic pressure. The magnitude of the osmotic pressure depends on the inherent properties of the solution, i.e. on the type, concentration and temperature of the concentrated solution and not on the properties of the semipermeable membrane. If a pressure greater than the osmotic pressure is applied to the concentrated solution side, the solvent will flow in the opposite direction to the original direction of osmosis, and will start to flow from the concentrated solution to the dilute solution side, a process known as reverse osmosis. Reverse osmosis, which is a reverse migration motion of osmosis, is a separation method of separating solute from solvent in solution by selective interception of semipermeable membrane under pressure driving, and is widely used for purification and concentration of various liquids, wherein the most common application example is to remove impurities such as inorganic ions, bacteria, viruses, organic matters and colloids in raw water by reverse osmosis technology in water treatment process.
And adopting a two-stage roll type RO as a standard-reaching effluent guarantee unit of the leachate treatment system. Ammonia nitrogen in the evaporated distilled water can reach the standard stably through two-stage roll type RO treatment, the concentrated water quality of the roll type membrane is better, and the ammonia nitrogen returns to the foremost one-stage MVR evaporator to be further treated to reach the standard.
S7, deep processing
Performing advanced treatment on the effluent after the two-stage roll type RO treatment by adopting an ion exchange system;
the ion exchange method is a method for removing ammonia nitrogen in wastewater by using a material with strong selective adsorption on ammonia ions. The adsorbing material adopts one of zeolite molecular sieve, active carbon, montmorillonite and exchange resin. The zeolite is aluminosilicate with three-dimensional structure, and has regular pore channel structure and cavity, wherein clinoptilolite has strong selective adsorption capacity to ammonia ions, and the price is low.
S8, solidifying the concentrated solution
Pumping concentrated solution generated in the MVR evaporation treatment process into a mixing stirrer by a pump, adding a stabilizer, fully stirring and mixing, and conveying the slurry to a mold through a conveyor to be solidified and molded. The stabilizer comprises lime, cement and a chelating agent. Wherein the mass ratio of the lime to the cement to the chelating agent is 30:20:1.
pumping the concentrated solution after final evaporation into a mixing stirrer by a pump, and simultaneously conveying the stabilizer (one or more) from a stabilizer bin to the mixing stirrer. The concentrated solution and the curing agent are fully mixed and stirred in the mixing stirrer, and the proportion of the curing agents is adjusted through debugging, so that the solidification time is shortest, the solidification time has certain compressive strength, the dosage of the medicament is minimum, and the leaching rate of residues is minimum. Mixing and stirring are generally from 5 to 10 minutes. And after the slurry is fully mixed, conveying the slurry to a mold through a conveyor to be solidified and molded.
Step S9, tail gas treatment: non-condensable gas generated in the MVR evaporation treatment process and odor generated in the pH value adjusting process are collected in a tank body and conveyed to an acid-base washing tower through a fan for treatment.
According to the composition of the tail gas, the invention adopts the process of acid-base absorption and purification liquid absorption to treat the tail gas. The acid-base washing process utilizes the irreversible chemical reaction between the odor component and the main component of the chemical liquor to produce new odorless substance so as to achieve the aim of deodorization. The malodorous gas is sprayed and washed by acid and alkali liquor through a washing tower for deodorization, generally, the water washing can only remove soluble or partially slightly soluble malodorous substances in water, the acid washing can remove alkaline malodorous substances such as ammonia, amines and the like, and the alkali washing is suitable for removing malodorous substances such as hydrogen sulfide, lower fatty acid and the like.
Therefore, in order to completely remove high-concentration malodorous substances and H2S present in the exhaust gas, a multi-stage chemical scrubbing method may be generally used for deodorization. The chemicals often used are sulfuric acid and NaOH solution, etc.
Reaction of ammonia with water
When ammonia is dissolved in water, ammonia molecules and water molecules are combined into ammonia monohydrate (NH 3. H2O) through hydrogen bonds, and a small part of the ammonia monohydrate can be ionized into ammonium ions and hydroxide ions, so that the ammonia water is weakly alkaline. The reaction of ammonia in water can be expressed as: the ammonia monohydrate is unstable and is decomposed by heating to generate ammonia and water, three molecules, three ions and three equilibria exist in the ammonia water, and the molecules are as follows: NH3, NH 3. H2O, H O; ion: NH4+, OH-, H +; and (3) balancing: NH3+ H2O ⇌ NH 3. H2O, NH. H2O ⇌ NH4+ + OH-, H2O ⇌ H + + OH-
Reaction of ammonia with sulfuric acid
H2SO4+2NH3=2NH4HSO4 (when the mol ratio of ammonia gas to sulfuric acid is less than or equal to 1:1)
H2SO4+2NH3= (NH 4) 2SO4 (when the mol ratio of ammonia gas to sulfuric acid is more than or equal to 2:1)
3H2SO4+2NH3= (NH 4) 2SO4+ NH4HSO4 (ammonia to sulfuric acid molar ratio between 1:1 and 2:1)
Reaction of hydrogen sulfide with sodium hydroxide
The hydrogen sulfide reacts with alkali such as sodium hydroxide to generate soluble sodium sulfide. When the hydrogen sulfide is excessive, sodium hydrosulfide is generated, and is adjusted by adding alkali and is converted into sodium sulfide:
H2S+2NaOH=Na2S+2H2O、H2S+NaOH=NaHS+H2O、
NaHS+NaOH=Na2S+H2O
example 2
A leachate pretreatment process for a domestic garbage landfill comprises the following steps:
s1, pretreatment
Performing two-stage filtration on the landfill leachate by adopting a fiber filter and a core filter to reduce the content of suspended matters by 180-250mg/L;
the landfill leachate contains higher-content suspended matters, and the subsequent treatment units need to be pretreated to reduce the suspended matters in order to ensure the stable operation of the subsequent treatment units.
S2, adjusting the pH value
The garbage percolate from which suspended matters are removed is firstly lifted to a raw liquid tank by a pump, and concentrated sulfuric acid is added into the raw liquid tank by a metering pump and stirred simultaneously; in the process step, concentrated sulfuric acid is added, so that the scaling speed of an evaporator can be effectively reduced, the ammonia nitrogen in evaporation produced water can be reduced, the pH of the landfill leachate in the raw liquid tank is adjusted to 5.5-6.5 by the concentrated sulfuric acid, most of the ammonia nitrogen in the concentrated solution exists in the form of ammonium ions, and the ammonia nitrogen is prevented from evaporating out along with water vapor.
S3, concentrating by an MVR evaporator
Pumping the garbage percolate after pH adjustment into an MVR evaporator to evaporate water in the garbage percolate to form water vapor, wherein the water vapor enters an alkaline washing system, and the residual part of concentrated solution of the garbage percolate is collected in a hot well at the lower part of the MVR evaporator;
the MVR evaporator comprises a shell 200, a heat exchange tube set 201 is arranged in the shell 200, two ends of the heat exchange tube set 201 extend out of the shell 200, a steam collecting part 202 is arranged on one side of the shell 200, an inlet end of the heat exchange tube set 201 is communicated with the steam collecting part 202, a liquid collecting part 203 is arranged on the other side of the shell 200, an outlet end of the heat exchange tube set 201 is communicated with the liquid collecting part 203, a spray pipe 204 is arranged in the shell 200 on the upper side of the heat exchange tube set 201, the spray pipe 204 is communicated with a water inlet pipe 205, a steam outlet 206 is arranged on the upper portion of the shell 200, the steam outlet 206 is connected with a steam inlet of a steam compressor 207, a steam outlet of the steam compressor 207 is connected with the steam collecting part 202, a demister 208 is arranged in the steam outlet 206, the lower end of the liquid collecting part 203 is connected with a condensate liquid outlet pipe 209, a heat well 210 is arranged in the middle of the lower end of the shell 200, the heat well 210 is connected with a filter 211, a liquid outlet end of the filter 211 is connected with a drain pipe 212, a circulating pump 213 is communicated with the condensate liquid outlet 204, and a drain pipe 214 of the heat exchanger 214, and the condensate liquid outlet pipe 214 is connected with a drain pipe 214.
The preheated landfill leachate or/and concentrated solution stored in a hot well at the bottom of the MVR evaporator are mixed by a circulating pump and then pumped into a spray pipe at the upper part of the MVR evaporator, the landfill leachate or mixed solution is uniformly sprayed on the outer surface of a heat exchange pipe bundle to form a liquid film, the liquid film is heated, boiled and evaporated in the process of flowing downwards from the heat exchange pipe bundle, and the residual part, namely the concentrated solution, is collected in the hot well at the lower part of the evaporator.
The evaporation takes place at the tube bank surface, the regenerated steam of formation, through efficient vapor compressor with the pressure and the temperature improvement of steam, form the inside that saturated steam got into heat exchange tube bank, on the one hand give the incoming water film of tube bank surface with heat energy transfer in order to form the evaporation, on the other hand, this saturated steam is cooled off in the tube bank, distilled water forms and is collected the water cavity in the pipe, then flash distillation to a degasser, the organic gas that probably recondenses to distilled water can very effectually be eliminated in the flash distillation, defogging net can make the quality of distilled water better.
The concentrated solution after continuous concentration is collected at the bottom of the hot well and pumped to a separation chamber of a forced circulation evaporation system by a concentrated solution pump.
The invention utilizes the horizontal tube falling film MVR evaporator to perform concentration decrement firstly, reduces the processing amount of the forced circulation evaporator, has low energy consumption and reduces the operation cost integrally.
S4, steam alkali washing
Washing water vapor generated in the MVR evaporation treatment process by using high-temperature alkali liquor to enable COD in the vapor to react with the high-temperature alkali liquor and be trapped in the alkali liquor, so that the vapor is purified, the COD in the vapor distilled water is reduced, and the load of subsequent membrane advanced treatment is reduced;
certain COD is carried in the high-temperature steam generated by evaporation, most of the part of the COD belongs to organic acid, and the high-temperature liquid caustic soda is used for washing the high-temperature liquid caustic soda in the process step, so that more than 99% of the COD in the steam is intercepted in the liquid caustic soda through the reaction with the high-temperature liquid caustic soda, thereby purifying the steam, and reducing the COD in the steam distilled water and the load of deep membrane treatment.
S5, low-temperature forced circulation concentration of MVR
Controlling the garbage percolation concentrated solution generated in the MVR evaporation treatment process to enter an MVR low-temperature forced circulation concentration evaporator for treatment, sending the obtained concentrated solution to a concentrated solution solidification treatment device, and sending the obtained distilled water to a secondary RO treatment device for treatment;
s6, two-stage RO treatment
Treating the distilled water after MVR low-temperature forced circulation concentration and the distilled water generated by the MVR evaporator by adopting a two-stage roll type RO, and reducing the content of ammonia nitrogen in the distilled water;
the RO membrane, also called reverse osmosis membrane, applies pressure to raw water by a machine, so that water in the raw water permeates the RO membrane, fine impurities, excessive inorganic salts, organic matters, heavy metal ions, bacteria, viruses, pesticides, trichloromethane wastewater and other harmful substances in the raw water are generally intercepted, and the harmful foreign matters and salt are discharged by continuously discharged concentrated water.
A reverse osmosis membrane is a membrane having selectivity for a substance to be permeated is called a semipermeable membrane, and a membrane which is permeable only to a solvent but not to a solute is generally called an ideal semipermeable membrane. When the same volume of dilute solution (e.g., fresh water) and concentrated solution (e.g., brine) is placed on each side of the semi-permeable membrane, the solvent in the dilute solution will naturally flow through the semi-permeable membrane spontaneously to the concentrated solution side, a phenomenon known as osmosis. When the osmosis reaches the equilibrium, the liquid level of the concentrated solution side is higher than the liquid level of the dilute solution by a certain height, namely, a pressure difference is formed, and the pressure difference is the osmotic pressure. The magnitude of the osmotic pressure depends on the inherent properties of the solution, i.e., the nature, concentration and temperature of the concentrated solution and not on the properties of the semipermeable membrane. If a pressure greater than the osmotic pressure is applied to the concentrated solution side, the solvent will flow in the opposite direction to the original direction of osmosis, and will start to flow from the concentrated solution to the dilute solution side, a process known as reverse osmosis. Reverse osmosis, which is a reverse migration motion of osmosis, is a separation method of separating solute from solvent in solution by selective interception of semipermeable membrane under pressure driving, and is widely used for purification and concentration of various liquids, wherein the most common application example is to remove impurities such as inorganic ions, bacteria, viruses, organic matters and colloids in raw water by reverse osmosis technology in water treatment process.
And adopting a two-stage roll type RO as a standard outlet water guarantee unit of the percolate treatment system. Ammonia nitrogen in the evaporated distilled water can reach the standard stably through two-stage roll type RO treatment, the concentrated water quality of the roll type membrane is better, and the ammonia nitrogen returns to the foremost one-stage MVR evaporator to be further treated to reach the standard.
S7, deep processing
Performing advanced treatment on the effluent after the two-stage roll type RO treatment by adopting an ion exchange system;
the ion exchange method is a method for removing ammonia nitrogen in wastewater by using a material with strong selective adsorption on ammonia ions. The adsorbing material adopts one of zeolite molecular sieve, active carbon, montmorillonite and exchange resin. The zeolite is aluminosilicate with three-dimensional structure, and has regular pore channel structure and cavity, wherein clinoptilolite has strong selective adsorption capacity to ammonia ions, and the price is low.
S8, solidifying the concentrated solution
Pumping concentrated solution generated in the MVR evaporation treatment process into a mixing stirrer by a pump, adding a stabilizer, fully stirring and mixing, and conveying the slurry to a mold through a conveyor to be solidified and molded. The stabilizer comprises lime, cement and a chelating agent. Wherein the mass ratio of the lime to the cement to the chelating agent is 30:20:1.
pumping the concentrated solution after final evaporation into a mixing stirrer by a pump, and simultaneously conveying the stabilizer (one or more) from a stabilizer bin to the mixing stirrer. The concentrated solution and the curing agent are fully mixed and stirred in the mixing stirrer, and the proportion of the curing agents is adjusted through debugging, so that the solidification time is shortest, the solidification time has certain compressive strength, the dosage of the medicament is minimum, and the leaching rate of residues is minimum. The mixing and stirring are generally carried out for 5 to 10 minutes. And after the slurry is fully mixed, conveying the slurry to a mould through a conveyor to be solidified and molded.
Step S9, tail gas treatment: the non-condensable gas generated in the MVR evaporation treatment process and the odor generated in the pH value adjusting process are collected in the tank body and conveyed to the acid-base washing tower through the fan for treatment.
According to the composition of the tail gas, the invention adopts the process of acid-base absorption and purification liquid absorption to treat the tail gas. The acid-base washing process utilizes the irreversible chemical reaction between the odor component and the main component of the chemical liquor to produce new odorless substance so as to achieve the aim of deodorization. The malodorous gas is sprayed and washed by acid-alkali liquor through a washing tower for deodorization, generally water washing can only remove the soluble or partially slightly water-soluble malodorous substances, acid washing can remove the alkaline malodorous substances such as ammonia, amines and the like, and alkali washing is suitable for removing the malodorous substances such as hydrogen sulfide, lower fatty acid and the like.
Therefore, in order to completely remove high concentration of malodorous substances and H2S present in the exhaust gas, a multi-stage chemical scrubbing method may be generally used for deodorization. The chemicals often used are sulfuric acid and NaOH solution, etc.
Reaction of ammonia with water
When ammonia is dissolved in water, ammonia molecules and water molecules are combined into ammonia monohydrate (NH 3. H2O) through hydrogen bonds, and a small part of the ammonia monohydrate can be ionized into ammonium ions and hydroxide ions, so that the ammonia water is weakly alkaline. The reaction of ammonia in water can be expressed as: the ammonia monohydrate is unstable and is decomposed by heating to generate ammonia and water, three molecules, three ions and three equilibria exist in the ammonia water, and the molecules are as follows: NH3, NH 3. H2O, H O; ion: NH4+, OH-, H +; and (3) balancing: NH3+ H2O ⇌ NH 3. H2O, NH. H2O ⇌ NH4+ + OH-, H2O ⇌ H + + OH-
Reaction of ammonia with sulfuric acid
H2SO4+2NH3=2NH4HSO4 (when the mol ratio of ammonia gas to sulfuric acid is less than or equal to 1:1)
H2SO4+2NH3= (NH 4) 2SO4 (when the molar ratio of ammonia gas to sulfuric acid is not less than 2:1)
3H2SO4+2NH3= (NH 4) 2SO4+ NH4HSO4 (ammonia to sulfuric acid molar ratio between 1:1 and 2:1)
Reaction of hydrogen sulfide with sodium hydroxide
The hydrogen sulfide reacts with alkali such as sodium hydroxide to generate soluble sodium sulfide. When the hydrogen sulfide is excessive, sodium hydrosulfide is generated, and is adjusted by alkali and then is converted into sodium sulfide:
H2S+2NaOH=Na2S+2H2O、H2S+NaOH=NaHS+H2O、
NaHS+NaOH=Na2S+H2O
the steps S1 and S2 of the invention are carried out in a pretreatment device, as shown in figure 3, wherein the pretreatment device comprises a base 1, a bracket 2, a shell 3, a raw liquid tank 31, a raw liquid pump 11, a liquid pump 6 and a first conveying pipe 7, the bracket 2 is connected with the upper side of the base 1, the shell 3 is connected with the upper part of the bracket 2, the raw liquid tank 31 for bearing percolate is arranged on the shell 3, the raw liquid pump 11 communicated with the raw liquid tank 31 is arranged at the lower part of the raw liquid tank 31, two first conveying pipes 7 are arranged at the upper part and the lower part, one end of the first conveying pipe 7 at the upper part is communicated with the raw liquid tank 31, and the liquid pump 6 is communicated between the other end and one end of the other first conveying pipe 7.
As shown in fig. 2, the filter device further comprises a fiber filter 4 and a core filter 5, wherein the fiber filter 4 and the core filter 5 communicated with the fiber filter 4 are installed on the upper side of the base 1, and the core filter 5 is communicated with the lower first conveying pipe 7.
As shown in fig. 4, the device further comprises a metering pump 8, and the metering pump 8 communicated with the liquid storage tank 10 is installed on the upper side of the right part of the shell 3 in a bolt connection mode.
As shown in fig. 4, the device further comprises a support plate 9, a liquid storage tank 10 and a second delivery pipe 101, the liquid storage tank 10 for storing concentrated sulfuric acid is connected to the rear side of the middle part of the housing 3 through the support plate 9, and the second delivery pipe 101 is communicated between the liquid storage tank 10 and the metering pump 8.
As shown in fig. 3, the device further comprises a mounting frame 12, a motor 13 and a rotating shaft 14, the motor 13 is mounted on the left side of the raw liquid tank 31 through the mounting frame 12, and the rotating shaft 14 rotatably penetrating through the raw liquid tank 31 is connected to an output shaft of the motor 13.
As shown in fig. 3, the fan blade device further includes a fan blade 15, and the fan blade 15 is connected to the rotating shaft 14.
The operator can use the corresponding technical scheme in this device in the technique of leachate preprocessing device for the domestic waste landfill according to the concrete situation, when the operator needs to use this device to assist the operation of leachate preprocessing, firstly, the operator injects the leachate into the inside of the fiber filter 4, inject concentrated sulfuric acid into the inside of the liquid storage tank 10, the leachate can flow into the inside of the core filter 5 through the fiber filter 4, so as to carry out two-stage filtration on the leachate through the fiber filter 4 and the core filter 5, thereby ensuring that the effluent suspended matter is reduced to 200mg/L, then the operator starts the liquid suction pump 6, the liquid suction pump 6 can lift the leachate from the inside of the core filter 5 through removing the suspended matter to the inside of the raw liquid tank 31 through the first delivery pipe 7, after the leachate is lifted to the inside of the raw liquid tank 31, the operator restarts the metering pump 8, the metering pump 8 can input the concentrated sulfuric acid from the inside of the liquid storage tank 10 through the second delivery pipe 101 to the inside of the raw liquid tank 31 to mix with the leachate, at this moment, the operator starts the motor 13, the output shaft of the motor 13 can drive the flabells 15 to rotate the impeller 15, the impeller 15 can reduce the concentrated sulfuric acid evaporation speed of the concentrated sulfuric acid evaporation liquid into the concentrated ammonia nitrogen evaporation liquid of the concentrated ammonia nitrogen evaporation system to reduce the concentrated ammonia nitrogen evaporation, and the concentrated ammonia nitrogen evaporation, the concentrated ammonia nitrogen evaporation water evaporation process of the concentrated ammonia nitrogen evaporation system after the concentrated leachate is reduced, and the concentrated ammonia nitrogen evaporation, the concentrated ammonia nitrogen evaporation system, the concentrated ammonia nitrogen evaporation.
The foregoing shows and describes the general principles and features of the present invention, together with the advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (10)
1. A leachate pretreatment process for a domestic garbage landfill is characterized by comprising the following steps:
s1, pretreatment
Performing two-stage filtration on the landfill leachate by adopting a fiber filter and a core filter to reduce the content of suspended matters by 180-250mg/L;
s2, adjusting the pH value
The garbage percolate from which suspended matters are removed is firstly lifted to a raw liquid tank by a pump, concentrated sulfuric acid is added into the raw liquid tank by a metering pump, and stirring is carried out simultaneously, so that the pH is adjusted to 5.5-6.5;
s3, concentrating by an MVR evaporator
Pumping the garbage percolate after pH adjustment into an MVR evaporator to evaporate water in the garbage percolate to form water vapor, wherein the water vapor enters an alkaline washing system, and the residual part of concentrated solution of the garbage percolate is collected in a hot well at the lower part of the MVR evaporator;
s4, steam alkali washing
Washing water vapor generated in the MVR evaporation treatment process by using high-temperature alkali liquor to enable COD in the vapor to react with the high-temperature alkali liquor and be trapped in the alkali liquor, so that the vapor is purified, the COD in the vapor distilled water is reduced, and the load of subsequent membrane advanced treatment is reduced;
s5, low-temperature forced circulation concentration of MVR
Controlling the garbage percolation concentrated solution generated in the MVR evaporation treatment process to enter an MVR low-temperature forced circulation concentration evaporator for treatment, sending the obtained concentrated solution to a concentrated solution solidification treatment device, and sending the obtained distilled water to a secondary RO treatment device for treatment;
s6, two-stage RO treatment
Treating distilled water after MVR low-temperature forced circulation concentration and distilled water generated by an MVR evaporator by adopting two-stage roll type RO, and reducing the content of ammonia nitrogen in the distilled water;
s7, deep processing
Performing advanced treatment on the effluent after the two-stage roll type RO treatment by adopting an ion exchange system;
s8, solidifying the concentrated solution
Pumping concentrated solution generated in the MVR evaporation treatment process into a mixing stirrer by a pump, adding a stabilizer, fully stirring and mixing, and conveying the slurry to a mold through a conveyor to be solidified and molded.
2. The leachate pretreatment process for the domestic waste landfill as claimed in claim 1, further comprising step S9, tail gas treatment: the non-condensable gas generated in the MVR evaporation treatment process and the odor generated in the pH value adjusting process are collected in the tank body and conveyed to the acid-base washing tower through the fan for treatment.
3. The process of claim 2, wherein the acid-base washing tower uses sulfuric acid and NaOH solution as washing agent.
4. The process of claim 1, wherein the stabilizing agent comprises lime, cement, and chelating agent.
5. The leachate pretreatment process for a domestic waste landfill as claimed in claim 1, wherein said MVR evaporator comprises a housing (200), a heat exchange tube set (201) is disposed in said housing (200), both ends of said heat exchange tube set (201) extend out of said housing (200), a vapor collecting part (202) is disposed at one side of said housing (200), an inlet end of said heat exchange tube set (201) is connected to said vapor collecting part (202), a liquid collecting part (203) is disposed at the other side of said housing (200), an outlet end of said heat exchange tube set (201) is connected to said liquid collecting part (203), a spray pipe (204) is disposed in said housing (200) at an upper side of said heat exchange tube set (201), said spray pipe (204) is connected to a water inlet pipe (205), a vapor outlet (206) is disposed at an upper portion of said housing (200), said vapor outlet (206) is connected to a vapor inlet of a vapor compressor (207), a vapor outlet of said vapor compressor (207) is connected to said vapor collecting part (202), a vapor pressure outlet (206) is disposed in said housing (206), a liquid outlet (210) of said vapor trap is connected to a condensate trap (210), and a condensate trap (210) is connected to a lower end of said vapor trap (210), the liquid outlet end of the filter (211) is connected with a water outlet pipe (212), the liquid outlet end of the filter (211) is communicated with the spray pipe (204) through a circulating pump (213), the lower end of the hot well (210) is communicated with the water outlet pipe (212), the heat exchanger (214) is further included, and the condensate liquid outlet pipe (209), the water outlet pipe (212) and the water inlet pipe (205) are respectively connected with the heat exchanger (214).
6. The leachate pretreatment process for the domestic garbage landfill according to claim 1, wherein the step S1 and the step S2 are performed in a pretreatment device, wherein the pretreatment device comprises a base (1), a support (2), a shell (3) and a raw liquid tank (31), the support (2) is connected to the upper side of the base (1), the shell (3) is connected to the upper portion of the support (2), the raw liquid tank (31) for bearing leachate is arranged on the shell (3), the leachate pretreatment process further comprises a raw liquid pump (11), a liquid pump (6) and a first conveying pipe (7), the raw liquid pump (11) communicated with the raw liquid tank (31) is installed at the lower portion of the raw liquid tank (31), the first conveying pipe (7) is provided with two upper portions and lower portions, one end of the first conveying pipe (7) above is communicated with the raw liquid tank (31), and the liquid pump (6) is communicated between the other end of the other first conveying pipe (7).
7. The leachate pretreatment process for the domestic waste landfill according to claim 5, further comprising a fiber filter (4) and a core filter (5), wherein the fiber filter (4) and the core filter (5) communicated with the fiber filter (4) are installed on the upper side of the base (1), and the core filter (5) is communicated with the first lower delivery pipe (7).
8. The leachate pretreatment process for the landfill according to claim 5, further comprising a metering pump (8), wherein the metering pump (8) is installed on the upper right side of the housing (3) and is communicated with the liquid storage tank (10).
9. The leachate pretreatment process for the municipal solid waste landfill according to claim 7, further comprising a support plate (9), a liquid storage tank (10) and a second delivery pipe (101), wherein the liquid storage tank (10) for storing concentrated sulfuric acid is connected to the rear side of the middle of the housing (3) through the support plate (9), and the second delivery pipe (101) is communicated between the liquid storage tank (10) and the metering pump (8).
10. The leachate pretreatment process for the domestic garbage landfill according to claim 5, further comprising a mounting rack (12), a motor (13) and a rotating shaft (14), wherein the motor (13) is mounted on the left side of the raw liquid tank (31) through the mounting rack (12), the rotating shaft (14) rotatably penetrating through the raw liquid tank (31) is connected to an output shaft of the motor (13), and further comprising fan blades (15), and the fan blades (15) are connected to the rotating shaft (14).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211361255.1A CN115710062A (en) | 2022-11-02 | 2022-11-02 | Leachate pretreatment process for household garbage landfill |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211361255.1A CN115710062A (en) | 2022-11-02 | 2022-11-02 | Leachate pretreatment process for household garbage landfill |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115710062A true CN115710062A (en) | 2023-02-24 |
Family
ID=85231953
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211361255.1A Pending CN115710062A (en) | 2022-11-02 | 2022-11-02 | Leachate pretreatment process for household garbage landfill |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115710062A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115846373A (en) * | 2023-03-03 | 2023-03-28 | 庆阳高晨工业危险废弃物处置有限公司 | Dangerous solid waste leachate treatment device |
| CN117088444A (en) * | 2023-08-28 | 2023-11-21 | 武汉天源环保股份有限公司 | High ammonia nitrogen organic wastewater treatment system and method |
-
2022
- 2022-11-02 CN CN202211361255.1A patent/CN115710062A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115846373A (en) * | 2023-03-03 | 2023-03-28 | 庆阳高晨工业危险废弃物处置有限公司 | Dangerous solid waste leachate treatment device |
| CN115846373B (en) * | 2023-03-03 | 2023-04-21 | 庆阳高晨工业危险废弃物处置有限公司 | Dangerous solid waste processing apparatus for leachate |
| CN117088444A (en) * | 2023-08-28 | 2023-11-21 | 武汉天源环保股份有限公司 | High ammonia nitrogen organic wastewater treatment system and method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101209881B (en) | System for processing leachate of garbage burning factory | |
| CN106242163B (en) | A kind of processing method of percolate embrane method concentrate | |
| CN115710062A (en) | Leachate pretreatment process for household garbage landfill | |
| CN102295378B (en) | Treatment and recycling method of ammonia nitrogen containing high-salt catalyst wastewater | |
| US20120315209A1 (en) | Methods and systems for treating water streams | |
| CN205740622U (en) | A kind of percolate coagulating sedimentation, evaporation joint processing system | |
| CN103319042A (en) | High-salt complex wastewater reuse and zero discharge integrated equipment and technology | |
| CN110683716A (en) | Wastewater treatment process for wastewater generated by automobile accessory coating production line | |
| CN206352096U (en) | Desulfurization wastewater zero-discharge treatment system is carried out using flue evaporative crystallization | |
| CN105236627A (en) | Papermaking tail water/recycled water reusing zero-discharge processing method | |
| CN112047553A (en) | PTA high-salinity wastewater treatment, reuse and zero-discharge system and method | |
| CN208684674U (en) | Processing system for garbage filter concentrate zero-emission | |
| CN104628065A (en) | Chemical pharmaceutical wastewater treatment system and method | |
| CN204779248U (en) | A sewage treatment system for landfill leachate | |
| CN205974184U (en) | Processing system of landfill leachate embrane method concentrate | |
| CN211226804U (en) | Membrane concentrate minimizing processing system | |
| CN205575835U (en) | Electroplating wastewater treatment system | |
| CN105174587B (en) | A kind of slurrying vacuum in draft tube Zero discharge treatment method | |
| CN201952316U (en) | Device for recycling tanning advanced treatment waste water | |
| CN218811161U (en) | Full-quantization treatment device for percolate of household garbage landfill | |
| CN207483528U (en) | Garbage percolation liquid treating system | |
| CN216236502U (en) | Landfill leachate treatment system | |
| CN212174700U (en) | Multistage enrichment facility of landfill leachate | |
| CN206127019U (en) | Device that joint fenton oxidation handled dense water of reverse osmosis is strained to modified receiving | |
| CN105036444B (en) | Minimizing and recycling Treated sewage reusing Zero-discharge treating process |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |