CN212403770U - Multistage crystallization precipitation treatment system for wastewater desalination - Google Patents
Multistage crystallization precipitation treatment system for wastewater desalination Download PDFInfo
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Abstract
The utility model provides a multistage crystallization precipitation treatment system for wastewater desalination, which is sequentially provided with a crystal reaction part, a neutralization reaction tank and a neutralization precipitation tank along the water inlet direction of saline wastewater, wherein the crystal reaction part comprises at least one crystal reaction unit, and the crystal reaction unit is sequentially provided with a crystal reaction tank and a crystal precipitation tank along the water inlet direction of the saline wastewater; the water inlet of the crystal reaction tank is externally connected with a calcium agent storage tank, an auxiliary agent storage tank and an aluminum agent storage tank, and the water inlet of the neutralization reaction tank is externally connected with a neutralizer storage tank; the sludge outlets of the crystal precipitation tank and the neutralization precipitation tank are sequentially externally connected with a first sludge pump and a first dehydrator along the sludge outlet direction, and the first dehydrator is connected with the water inlet of the crystal reaction tank. The novel multistage crystallization precipitation treatment system for wastewater desalination has the advantages of energy consumption and treatment cost saving, no influence of organic matter content in water, capability of being used for pretreatment of wastewater biochemical treatment and the like.
Description
Technical Field
The utility model belongs to the technical field of sewage treatment, a multistage crystallization precipitation treatment system of waste water desalination is related to.
Background
Various industrial waste waters often contain high concentrations of soluble salts, such as sodium, potassium, calcium, magnesium and ammonium salts, and the anions that make up these salts are typically chloride, sulfate, nitrate and carbonate. The total concentration (TDS) of these soluble salts can often be as high as thousands or even tens of thousands of milligrams per liter, and in individual cases even hundreds of thousands of milligrams per liter. The discharge of a large amount of salt into natural fresh water bodies can cause the salinity of surface water and underground water to be increased, thereby changing the physical and chemical properties of the water environment and even influencing the stability and health of an ecological system to a certain extent.
The discharged wastewater is limited by TDS in many cities, particularly when the treated wastewater is recycled, the TDS is often required to reach a certain concentration or below, for example, the total dissolved solids of urban miscellaneous water must be lower than 1000-1500 mg/L; for occasions with zero discharge requirements, the wastewater is considered to enter a production device for recycling, and soluble salt is also required to be removed; in addition, the biochemical treatment of the wastewater is difficult due to the excessively high salt concentration, and in order to ensure the effective biochemical treatment of the wastewater, the high-salt wastewater needs to be subjected to desalination pretreatment; many conventional desalination processes, such as reverse osmosis, electrodialysis, ion exchange, etc., produce a certain amount of concentrated (salt) water, which requires additional desalination.
The common desalination processes in the current wastewater treatment include chemical precipitation, ion exchange, reverse osmosis, electrodialysis, evaporative crystallization, and the like. Chemical precipitation methods remove certain ions by changing the pH of the wastewater or adding another acid or salt to cause the ions to form a precipitate that is insoluble or poorly soluble in water. Chemical precipitation methods often do not remove total salts efficiently due to the introduction of new ions; the ion exchange method adopts anion and cation resin to replace anion and cation in the wastewater, and simultaneously releases hydroxide ions and hydrogen ions into the water respectively and reacts to generate water. However, ion exchange sites on the surface of the resin need to be regenerated after saturation, and the regeneration of the anion and cation resin needs to replace adsorbed anions and cations with high-concentration alkali or acid respectively, so that a certain amount of concentrated brine is generated and needs to be treated separately; reverse osmosis and electrodialysis water or ions are moved across a membrane by reverse osmosis pressure or by an electric field to effect separation of the ions from the water. While obtaining pure water, the method also generates a certain amount of concentrated (salt) water to be treated, and the potential energy required by transmembrane movement must be provided by high water pressure or high-voltage electric field, which consumes a large amount of energy; ion exchange, electrodialysis and reverse osmosis processes remove salt and produce concentrated (salt) water in volumes typically greater than 30% of the volume of water treated. Evaporative crystallization is to raise the temperature of the waste water above the boiling point of water to evaporate the water into steam, to make the salt concentration in the water reach above its solubility, at this time the salt will form crystals to precipitate from the water, and then to separate the salt from the water by centrifugal action. The steam is condensed to become desalted water which can be recycled or discharged into wastewater for treatment. The process needs to heat water to the boiling point of water, the energy consumption is large, and the energy consumed by evaporation of water per ton is 30-40 kilowatts. In addition, if the waste water contains organic matters, the salt content cannot be completely removed by the evaporation crystallization method; meanwhile, scales are easy to form in the evaporating pipe, so that the service life of the evaporating pipe is shortened, and long-term stable operation is difficult to implement.
The method for embedding toxic and harmful substances such as heavy metals and radioactive substances by utilizing the solidification effect of cement is implemented in Europe as early as the first half of the last century, and the technology is also used in the United states in large quantities for treating the toxic and harmful substances in the 70-80 years of the last century. Intensive research shows that the cement curing effect is mainly caused by the existence of calcium-aluminum crystals in the cement, the calcium-aluminum crystals are insoluble in water, have strong agglomeration effect and have a complex structure formed by crosslinking 4 columnar bodies. The structure enables other ions mixed in water to diffuse into the inner cavity of the water cavity and be embedded, and meanwhile, surrounding hydrogen atoms and hydroxide ions can be replaced by other ions, so that the ions are fixed in the calcium-aluminum crystal.
Numerous studies have demonstrated that the formation of calcium-aluminium crystals can be carried out in aqueous solution. There are many different reaction modes for the formation of calcium-aluminum crystals in the liquid phase, and the following two are common:
CaO·Al2O3 3++Ca2SO4 2-+H2O→CaO·Al2O3 3+·Ca2SO4 2-·H2O
Ca2++Al3++SiO3 2-→Ca2+·Al3+·SiO3 2-
patent CN104603068A discloses a method for removing sulfate, calcium and/or other metal ions in wastewater, which aims at the treatment of wastewater containing sulfate radical by adding Ca (OH)2The calcium-containing compound is used to adjust the pH and the aluminum-containing compound to allow the sulfate and soluble Ca ions in the water to be incorporated into the gypsum precipitate and the calcium sulfoaluminate precipitate.
WO98/55405, publication "sulfate treatment in mine effluent (waste effluence) from the International acid control network (INAP), 10 months 2003, Lorax Environmental", publications DE3709905, EP0584502, EP0250626, etc., all relate to the use of Al (OH)3Aluminum, aluminumSodium or Al2O3And removing sulfate radicals and calcium ions in the sulfur-containing wastewater by using the aluminum-containing compound.
The process mentioned in the above publication can reduce sulfate ions in water from tens of thousands to thousands of ppm to below 100 ppm. The method is used for removing sulfate in the wastewater around the selection of gypsum precipitation and calcium sulphoaluminate precipitation steps, the setting of reaction conditions, the selection of reaction agents and the setting of the adding amount. While there is a natural attendant removal of a portion of the other ions during their reaction, these methods are not directly applicable to the efficient removal of total dissolved salts from water, especially for sulfate-free wastewater desalination, and are not applicable.
In summary, in the existing wastewater desalination technology, the methods such as ion exchange, reverse osmosis, electrodialysis, etc. have high energy consumption, and the desalination is not thorough, and concentrated (saline) water with high salt concentration can be generated, while evaporative crystallization has high energy consumption and high treatment cost; in addition, the biochemical treatment is generally considered to be adopted for the treatment of organic wastewater with high salt content, such as chemical wastewater, pharmaceutical wastewater, leather wastewater, paper-making wastewater, garbage leachate and the like, but because the biochemical treatment efficiency is affected by the high salt concentration, the desalination is generally expected before the biochemical treatment, but because the organic matters contained in the wastewater easily cause resin pollution and/or membrane pore blockage, the wastewater cannot be directly desalted by the methods of ion exchange, reverse osmosis and electrodialysis, and if the wastewater is desalted by the evaporative crystallization method, the energy consumption is high, a large amount of impurities are mixed in the crystals, and the separated crystals cannot be utilized; the existing desalting method can not distinguish heavy metal components from non-heavy metal components, so that heavy metal is mixed in non-heavy metal, a large amount of toxic and harmful solid waste containing heavy metal is generated, and the disposal cost of the solid waste is very high. The method for treating the sulfate-containing wastewater by utilizing gypsum precipitation and calcium sulfoaluminate precipitation aims at introducing other impurity ions into sulfate ions in the wastewater, and the used reaction medicament, reaction steps, pH conditions and the like cannot be used for desalting treatment of a large amount of salt-containing wastewater, particularly desalting treatment of wastewater without sulfate radicals.
SUMMERY OF THE UTILITY MODEL
In view of the above-mentioned shortcomings of the prior art, the present invention provides a multi-stage crystallization precipitation treatment system for desalting wastewater, which utilizes the crystallization precipitation effect of calcium-aluminum crystal to transfer the soluble ions in the wastewater to the calcium-aluminum crystal by using the mechanisms of surface in-situ ion exchange, intramolecular embedding, etc., so as to remove the salt from the water.
In order to achieve the above and other related objects, the present invention provides a multi-stage crystallization precipitation treatment system for wastewater desalination, which is sequentially provided with a crystal reaction component, a neutralization reaction tank, and a neutralization precipitation tank along the inflow direction of saline wastewater, wherein the crystal reaction component comprises at least one crystal reaction unit, and the crystal reaction unit is sequentially provided with a crystal reaction tank and a crystal precipitation tank along the inflow direction of saline wastewater; a water inlet of the crystal reaction tank is externally connected with a calcium agent storage tank, an auxiliary agent storage tank and an aluminum agent storage tank, and a water inlet of the neutralization reaction tank is externally connected with a neutralizer storage tank; and the sludge outlets of the crystal precipitation tank and the neutralization precipitation tank are sequentially externally connected with a first sludge pump and a first dehydrator along the sludge outlet direction, and the first dehydrator is connected with the water inlet of the crystal reaction tank.
Preferably, the system is still including heavy metal reaction tank, heavy metal precipitation tank, heavy metal reaction tank, heavy metal precipitation tank and crystalline solid reaction unit set gradually along the waste water inflow direction that contains salt, the water inlet of heavy metal reaction tank is external to have the calcium agent storage tank, the mud outlet of heavy metal precipitation tank is external to have second sludge pump, second hydroextractor along a mud direction in proper order, the second hydroextractor still is connected with the water inlet of heavy metal reaction tank.
More preferably, the second sludge pump is a conventionally used sludge pump.
More preferably, the second dehydrator is selected from one of a plate-and-frame filter press, a stacked screw dehydrator or a centrifugal dehydrator.
More preferably, the system further comprises a flocculant storage tank, and the flocculant storage tank is respectively connected with the water inlet of the crystal reaction tank and the water inlet of the heavy metal reaction tank.
More preferably, a pH meter is arranged in the heavy metal reaction tank.
More preferably, a stirring paddle is arranged in the heavy metal reaction tank.
Preferably, a pH meter is arranged in the neutralization reaction tank and the crystal reaction tank.
Preferably, stirring paddles are arranged in the neutralization reaction tank and the crystal reaction tank.
Preferably, the calcium agent employed in the calcium agent storage tank includes, but is not limited to, hydroxides of alkaline earth metals, oxides of alkaline earth metals, slag containing hydroxides of alkaline earth metals and/or oxides of alkaline earth metals.
More preferably, the calcium agent used in the calcium agent storage tank is selected from calcium hydroxide Ca (OH)2CaO, Ca (OH) containing calcium hydroxide2And/or slag of calcium oxide CaO.
Most preferably, the calcium agent used in the calcium agent storage tank is calcium hydroxide Ca (OH)2Or calcium oxide CaO.
More preferably, the slag is high calcium fly ash.
Preferably, the adjuvant used in the adjuvant storage tank includes, but is not limited to, calcium sulfate, magnesium sulfate, aluminum sulfate, iron sulfate, sodium silicate, and minerals containing the above compounds.
More preferably, the adjuvant used in the adjuvant storage tank is selected from one or more of calcium sulfate, magnesium sulfate, aluminum sulfate, ferric sulfate and sodium silicate.
Preferably, the aluminum agent used in the aluminum agent storage tank includes, but is not limited to, calcium aluminate, magnesium aluminate, iron aluminate, aluminum hydroxide, aluminum chloride, minerals containing the above compounds, and wastewater containing the above compounds. The waste water can be aluminum product processing waste water.
More preferably, the aluminum agent used in the aluminum agent storage tank is selected from one or more of calcium aluminate, magnesium aluminate, ferric aluminate, aluminum hydroxide and aluminum chloride.
Preferably, the neutralizing agent employed in the neutralizing agent reservoir includes, but is not limited to, carbonic acid, CO2Containing CO2Flue gas of。
More preferably, the neutralizing agent employed in the neutralizing agent reservoir is selected from the group consisting of carbonic acid, CO2Or containing CO2One of the flue gases of (1).
Preferably, the flocculant adopted in the flocculant storage tank is selected from one or more of polyaluminium chloride, Polyacrylamide (PAM), aluminium chloride, aluminium sulfate, ferric chloride, ferric sulfate, ferrous sulfate and aluminum ferric sulfate.
Preferably, the first dehydrator is one selected from a plate-and-frame filter press, a stacked screw dehydrator or a centrifugal dehydrator.
Preferably, the first sludge pump is a conventionally used sludge pump.
As mentioned above, the utility model provides a pair of multistage crystallization precipitation processing system of waste water desalination has following beneficial effect:
(1) the utility model provides a pair of multistage crystallization precipitation processing system of waste water desalination does not produce dense (salt) liquid at the desalination in-process, and the waste salt that obtains directly fixes in chemical sediment such as calcium-aluminum crystal solid with the form of solid.
(2) The utility model provides a pair of multistage crystallization precipitation treatment system of waste water desalination, the poisonous and harmful composition of heavy metal that contains in waste water is got rid of in a reaction precipitation unit alone, can make the amount of the poisonous and harmful mud that contains the heavy metal drop to minimum like this to practice thrift poisonous and harmful waste's treatment cost.
(3) The utility model provides a pair of multistage crystallization precipitation processing system of waste water desalination especially is suitable for the desalination of the high desalination of salt waste water that contains organic component or the desalination of salt-tolerant biochemical technology processing back waste water, and these waste waters are owing to contain organic component, and membrane or ion exchange resin are very easily blockked up or pollute when using embrane method or ion exchange method, and adopt the evaporation crystallization method also can make the crystallization difficulty and be difficult to obtain purer salinity because waste water contains the organic matter, and the operation can't go on. The salt concentration of the wastewater with thousands to tens of thousands of milligrams per liter can be reduced to hundreds of milligrams or even tens of milligrams per liter after treatment.
(4) The utility model provides a pair of multistage crystallization precipitation processing system of waste water desalination is applicable to the desalination preliminary treatment before the high salt waste water biochemical treatment that contains for biochemical treatment need not to cultivate dedicated salt-tolerant bacterial, improves biochemical treatment process's universality.
(5) The utility model provides a pair of multistage crystallization precipitation processing system of waste water desalination utilizes the crystallization precipitation effect of calcium aluminium crystal body, utilizes mechanism such as surface normal position ion exchange, intramolecular embedding to shift to the calcium aluminium crystal body with the solubility ion in the waste water and goes to can follow aquatic and detach. The system can save energy consumption and treatment cost. In addition, the system can be used for desalting without being influenced by the content of organic matters in water, and can be used for pretreatment of wastewater biochemical treatment such as reverse osmosis desalting or distillation desalting.
Drawings
FIG. 1 is a schematic diagram showing the structure of a multistage crystallization precipitation treatment system for wastewater desalination according to the present invention.
Reference numerals
1 heavy metal reaction tank
2 heavy metal precipitation tank
3 crystalline reaction part
4 crystalline reaction unit
5 crystal reaction tank
6 crystal precipitation tank
7 neutralization reaction tank
8 neutralizing and precipitating tank
9 first sludge pump
10 first dehydrator
11 second sludge pump
12 second dehydrator
13 calcium agent storage tank
14 auxiliary agent storage tank
15 aluminum agent storage tank
16 flocculating agent storage tank
17 neutralizer storage tank
Detailed Description
The following description is provided for illustrative purposes, and other advantages and features of the present invention will become apparent to those skilled in the art from the following detailed description.
Please refer to fig. 1. It should be understood that the structure, ratio, size and the like shown in the drawings attached to the present specification are only used for matching with the content disclosed in the specification, so as to be known and read by those skilled in the art, and are not used for limiting the limit conditions that the present invention can be implemented, so that the present invention has no technical essential meaning, and any structure modification, ratio relationship change or size adjustment should still fall within the scope that the technical content disclosed in the present invention can cover without affecting the function that the present invention can produce and the purpose that the present invention can achieve. Meanwhile, the terms such as "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for convenience of description, and are not intended to limit the scope of the present invention, and changes or adjustments of the relative relationship thereof may be made without substantial technical changes, and the present invention is also regarded as the scope of the present invention.
The utility model provides a multistage crystallization precipitation treatment system for wastewater desalination, as shown in figure 1, a crystal reaction part 3, a neutralization reaction tank 7 and a neutralization precipitation tank 8 are sequentially arranged along the water inlet direction of saline wastewater, the crystal reaction part 3 comprises at least one crystal reaction unit 4, and the crystal reaction unit 4 is sequentially provided with a crystal reaction tank 5 and a crystal precipitation tank 6 along the water inlet direction of saline wastewater; a water inlet of the crystal reaction tank 5 is externally connected with a calcium agent storage tank 13, an auxiliary agent storage tank 14 and an aluminum agent storage tank 15, and a water inlet of the neutralization reaction tank 7 is externally connected with a neutralizer storage tank 17; the sludge outlets of the crystal precipitation tank 6 and the neutralization precipitation tank 8 are sequentially externally connected with a first sludge pump 9 and a first dehydrator 10 along the sludge outlet direction, and the first dehydrator 10 is connected with the water inlet of the crystal reaction tank 5.
In a preferred embodiment, as shown in fig. 1, the system further includes a heavy metal reaction tank 1 and a heavy metal precipitation tank 2, the heavy metal reaction tank 1, the heavy metal precipitation tank 2 and the crystal reaction component 3 are sequentially arranged along the water inlet direction of the saline wastewater, a calcium agent storage tank 13 is externally connected to the water inlet of the heavy metal reaction tank 1, a sludge outlet of the heavy metal precipitation tank 2 is sequentially externally connected to a second sludge pump 11 and a second dehydrator 12 along the sludge outlet direction, and the second dehydrator 12 is further connected to the water inlet of the heavy metal reaction tank 1.
The heavy metal reaction tank 1 and the heavy metal precipitation tank 2 may be subjected to a preliminary precipitation reaction.
In a further preferred embodiment, as shown in fig. 1, the system further comprises a flocculant storage tank 16, and the flocculant storage tank 16 is connected to the water inlet of the crystalline reaction tank 5 and the water inlet of the heavy metal reaction tank 1 respectively.
In a further preferred embodiment, as shown in fig. 1, a pH meter is provided in the heavy metal reaction tank 1. For monitoring the pH value in the heavy metal reaction tank 1.
In a further preferred embodiment, as shown in fig. 1, a stirring paddle is arranged in the heavy metal reaction tank 1. The stirring paddle is used for stirring and mixing the reaction reagent in the heavy metal reaction tank 1.
The heavy metal reaction tank 1 is used for performing a preliminary precipitation reaction. The heavy metal precipitation tank 2 is used for solid-liquid separation after the preliminary precipitation reaction.
In a preferred embodiment, as shown in fig. 1, pH meters are arranged in the neutralization reaction tank 7 and the crystallization reaction tank 5. Is used for monitoring the pH value in the neutralization reaction tank 7 and the crystal reaction tank 5.
In a preferred embodiment, as shown in fig. 1, stirring paddles are arranged in the neutralization reaction tank 7 and the crystal reaction tank 5. The stirring paddle is used for stirring and mixing reaction reagents in the neutralization reaction tank 7 and the crystal reaction tank 5.
The crystal reaction tank 5 is used for carrying out precipitation reaction and repeated reaction. The crystal precipitation tank 6 is used for solid-liquid separation after precipitation reaction. The neutralization reaction tank 7 is used for performing a neutralization reaction. The neutralization precipitation tank 8 is used for solid-liquid separation after the neutralization reaction. The calcium agent storage tank 13, the adjuvant storage tank 14, the aluminum agent storage tank 15, the neutralizer storage tank 17 and the flocculant storage tank 16 are used for storing and adding a calcium agent, an adjuvant, an aluminum agent, a neutralizer and a flocculant respectively.
In the above embodiment, as shown in fig. 1, the first sludge pump 9 and the second sludge pump 11 are conventionally used sludge pumps.
In the above embodiment, as shown in fig. 1, the first dehydrator 10 and the second dehydrator 12 are selected from one of a plate-and-frame filter press, a stacked screw dehydrator, and a centrifugal dehydrator.
The first sludge pump 9 is used for conveying precipitates obtained by solid-liquid separation in the crystal precipitation tank 6 and the neutralization precipitation tank 8 to the first dehydrator 10 for dehydration. The first dehydrator 10 is configured to dehydrate precipitates obtained by solid-liquid separation in the crystallization precipitation tank 6 and the neutralization precipitation tank 8, and to reflux a clear liquid generated by dehydration to the crystallization reaction tank 5. The sludge generated by dehydration can be sent out to a solid waste treatment center for final treatment. The solid waste treatment center is an enterprise with solid waste disposal qualification or heavy metal recycling qualification.
The second sludge pump 11 is used for transferring the precipitate obtained by solid-liquid separation in the heavy metal precipitation tank 2 to the second dehydrator 12 for dehydration. The second dehydrator 12 is configured to dehydrate the precipitate obtained by solid-liquid separation in the heavy metal precipitation tank 2, and to reflux the clear liquid generated by dehydration to the heavy metal reaction tank 1. The sludge generated by dehydration can be sent out to a solid waste treatment center for final treatment. The solid waste treatment center is an enterprise with solid waste disposal qualification or heavy metal recycling qualification.
In the above embodiment, as shown in fig. 1, the calcium agent used in the calcium agent storage tank 13 includes, but is not limited to, a hydroxide of an alkaline earth metal, an oxide of an alkaline earth metal, a slag containing a hydroxide of an alkaline earth metal and/or an oxide of an alkaline earth metal.
In particular, the calcareous agent is collected in the tank 13The calcium agent is selected from calcium hydroxide Ca (OH)2CaO, Ca (OH) containing calcium hydroxide2And/or slag of calcium oxide CaO.
Further preferably, the calcium agent used in the calcium agent storage tank 13 is calcium hydroxide Ca (OH)2Or calcium oxide CaO.
Specifically, the slag is high calcium fly ash.
In the above embodiment, as shown in fig. 1, the adjuvant used in the adjuvant storage tank 14 includes, but is not limited to, calcium sulfate, magnesium sulfate, aluminum sulfate, iron sulfate, sodium silicate, and minerals containing the above compounds.
Specifically, the adjuvant used in the adjuvant storage tank 14 is selected from one or more of calcium sulfate, magnesium sulfate, aluminum sulfate, ferric sulfate, and sodium silicate.
In the above embodiment, as shown in fig. 1, the aluminum agent used in the aluminum agent storage tank 15 includes, but is not limited to, calcium aluminate, magnesium aluminate, iron aluminate, aluminum hydroxide, aluminum chloride, minerals containing the above compounds, and wastewater containing the above compounds. The waste water can be aluminum product processing waste water.
Specifically, the aluminum agent used in the aluminum agent storage tank 15 is selected from one or more of calcium aluminate, magnesium aluminate, ferric aluminate, aluminum hydroxide, and aluminum chloride.
In the above embodiment, as shown in fig. 1, the neutralizer used in the neutralizer storage tank 17 includes, but is not limited to, carbonic acid and CO2Containing CO2The flue gas of (1).
Specifically, the neutralizer used in the neutralizer storage tank 17 is selected from carbonic acid and CO2Or containing CO2One of the flue gases of (1).
In the above embodiment, as shown in fig. 1, the flocculant used in the flocculant storage tank 16 is selected from one or more of polyaluminium chloride, Polyacrylamide (PAM), aluminium chloride, aluminium sulfate, ferric chloride, ferric sulfate, ferrous sulfate, and ferric aluminum sulfate.
The following description will be made with reference to fig. 1 for describing a specific process of using a multistage crystallization precipitation treatment system for wastewater desalination according to the present invention.
After obtaining a multistage crystallization precipitation treatment system for wastewater desalination as shown in fig. 1, when a large amount of heavy metal ions are contained in saline wastewater, a user inputs wastewater containing thousands ppm of salt into the heavy metal reaction tank 1, and adds a calcium agent from a calcium agent storage tank 13: ca (OH)2And carrying out a pre-precipitation reaction, wherein the reaction is kept for 40 minutes, and the pH value is controlled to be 9.0, so that heavy metal ions in the wastewater can react to generate precipitates. At the same time, other ions in the wastewater, such as SO4 2+And CO3 2+And also partially reacts with calcium ions in the calcium agent to form precipitates. Continuously detecting pH value of the reaction solution by using a pH meter to control the addition of calcium agent and make other ions such as SO in the wastewater4 2+And CO3 2+Remain in the dissolved state in the wastewater. In order to increase the precipitation effect of the precipitate, a flocculant is added from a flocculant storage tank 16: 100mg of aluminum sulfate is added into every 1L of salt-containing wastewater. And (3) the mixed solution after the reaction enters a heavy metal precipitation tank 2, and the heavy metal and part of other salts are removed by solid-liquid separation to obtain a pretreatment solution.
Then the pretreatment liquid flows into a crystal reaction part 3, sludge containing heavy metals is separated from water and is conveyed to a second dehydrator 12 by a second sludge pump 11 for sludge dehydration, clear liquid obtained by dehydration returns to a heavy metal reaction tank 1 for repeated treatment, and the dehydrated sludge is sent to a solid waste treatment center for treatment and disposal.
In the crystal reaction part 3, 2 crystal reaction units 4 are arranged, and each crystal reaction unit 4 is provided with a crystal reaction tank 5 and a crystal precipitation tank 6 in sequence along the water inlet direction of the salt-containing wastewater. The pretreatment liquid is put into a crystal reaction tank 5 of a 1 st crystal reaction unit 4, and a calcium agent storage tank 13 is added with a calcium agent: ca (OH)2Adding an auxiliary agent from an auxiliary agent storage tank 14: sodium silicate, adding aluminum agent from an aluminum agent storage tank 15: and (3) carrying out precipitation reaction on the magnesium aluminate, and keeping the reaction for 40 minutes, wherein the pH value is controlled to be 11.5, so that the metal ions in the pretreatment liquid are subjected to crystallization reaction to generate calcium-aluminum crystal precipitation. Measuring the content of Ca element in the pretreatment solution by ICP-AES according to the pH value of 11.5, and determining the addition of the auxiliary agent according to the content of Ca element in the pretreatment solutionThe addition amount of the aluminum agent is determined by the addition amount of the auxiliary agent. Wherein, the molar ratio of Ca element in the pretreatment liquid to anion in the adjuvant is 3: 1, the molar ratio of anions in the auxiliary agent to Al element in the aluminum agent is 1: 0.8, the anion in the auxiliary agent is silicate ion. The addition amount of the auxiliary agent is determined by determining the content of anions in the auxiliary agent. The content of Al element in the aluminum agent is determined, so that the addition amount of the aluminum agent is determined.
In order to make the calcium-aluminium crystalline precipitate faster, a flocculant is added from a flocculant storage tank 16: 100mg of aluminum sulfate is added into every 1L of salt-containing wastewater. The mixed liquid after the reaction of the calcium-aluminum crystal enters a crystal precipitation tank 6, so that the calcium-aluminum crystal can be separated from the water. The calcium-aluminum crystal is conveyed to a first dehydrator 10 by a first sludge pump 9 for sludge dehydration, clear liquid obtained by dehydration returns to the crystal reaction tank 5 for repeated treatment, and the dehydrated sludge is recycled as a cement additive. And (3) enabling supernatant obtained by the precipitation reaction to enter a crystal reaction tank 5 of a crystal reaction unit 4 of the 2 nd crystal reaction unit for repeating the treatment process, standing for 40 minutes in the reaction, and controlling the pH value to be 13.5 to finally obtain clear liquid.
Because the pH of the clarified liquor is relatively high and contains a certain concentration of calcium ions or other alkaline earth metal ions, neutralization is required before discharge and the concentration of calcium ions or other alkaline earth metal ions in the wastewater is reduced. Therefore, the clarified liquid obtained in the above-mentioned treatment step is fed into the neutralization reactor 7, and the neutralizer: after the neutralization reaction with carbonic acid, the pH of the clear solution was adjusted to 7.5, and the solution was allowed to flow into the neutralization and precipitation tank 8 to form calcium carbonate precipitate. The clear liquid obtained in the neutralization precipitation tank 8 is a desalted wastewater sample, and the desalted wastewater sample is discharged or returned to the process for recycling. The obtained calcium carbonate precipitate is merged into calcium-aluminum crystal precipitate and is conveyed to a first dehydrator 10 by a first sludge pump 9 for sludge dehydration, clear liquid obtained by dehydration is returned to a crystal reaction tank 5 for repeated treatment, and the dehydrated sludge is recycled as a cement additive.
Sampling the effluent at the water outlet of the treatment system for 3 times at intervals of 3 hours to obtain a desalted wastewater sample No. 1-3. Taking the inlet water at the water inlet of the treatment system, and simultaneously carrying out component detection on the inlet water and the desalted wastewater sample No. 1-3, wherein the measurement results are shown in Table 1. As can be seen from Table 1, after the treatment of the system, the TDS of the inlet water is reduced from 5410mg/L to below 250mg/L of the outlet water, the mean TDS removal rate reaches 96.30%, and the excellent desalting effect is achieved.
TABLE 1
After the salt-containing wastewater is treated, the inflow water at the water inlet of the treatment system, the pretreatment liquid after the pre-precipitation reaction and the outflow water flowing out of the treatment system are respectively sampled and then subjected to component test, and the test results are shown in table 2. As can be seen from Table 2, after the pre-precipitation treatment in the system, the amount of Cu, Fe, Mn and Zn in the feed water was reduced from 210mg/L, 880mg/L, 250mg/L and 703mg/L to 0.06mg/L, 0.35mg/L, 0.03mg/L and 0.01mg/L or less in the pretreatment solution, respectively, so that a good metal removal effect was obtained. After being treated by the system, SO in the inlet water4 2-The content of 9000mg/L of the desalted water is reduced to 30mg/L of the effluent water, so that the excellent desalting effect is achieved.
TABLE 2
After obtaining a multi-stage crystallization precipitation treatment system for desalting wastewater as shown in fig. 1, a user directly inputs wastewater containing several thousands ppm of salt into the crystallization reaction part 3 when the saline wastewater does not contain heavy metal ions. In the crystal reaction part 3, 2 crystal reaction units 4 are arranged, and each crystal reaction unit 4 is provided with a crystal reaction tank 5 and a crystal precipitation tank 6 in sequence along the water inlet direction of the saline wastewater. And (3) entering a 1 st crystal reaction part 3, adding a calcium agent from a calcium agent storage tank 13 into a crystal reaction tank 5 of a crystal reaction unit 4: CaO, adding an auxiliary agent from an auxiliary agent storage tank 14: magnesium sulfate, aluminum agent is added from an aluminum agent storage tank 15: and (3) carrying out precipitation reaction on ferric aluminate, keeping the reaction for 60 minutes, controlling the pH value to be 12, generating calcium-aluminum crystal precipitation, and combining soluble ions in the wastewater into the calcium-aluminum crystals in an in-situ ion exchange, molecular embedding or direct incorporation mode. And when the pH value is 12, determining the content of Ca element in the salt-containing wastewater by adopting ICP-AES, determining the addition amount of the auxiliary agent according to the content of Ca element in the salt-containing wastewater, and determining the addition amount of the aluminum agent according to the addition amount of the auxiliary agent. Wherein the molar ratio of Ca element in the salt-containing wastewater to anions in the auxiliary agent is 3: 1, the molar ratio of anions in the auxiliary agent to Al element in the aluminum agent is 1: 0.8, sulfate ions are taken as anions in the auxiliary agent. The addition amount of the auxiliary agent is determined by determining the content of anions in the auxiliary agent. The content of Al element in the aluminum agent is determined, so that the addition amount of the aluminum agent is determined. In this reaction step, the pH of the reaction solution was continuously monitored by a pH meter and used to control the addition of the calcium agent. The calcium agent is added in the reaction, on one hand, the pH value of the reaction solution is adjusted, and meanwhile, structural components are provided for the generation of calcium-aluminum crystals.
In order to make the calcium-aluminium crystalline precipitate faster, a flocculant is added from a flocculant storage tank 16: 100mg of aluminum sulfate is added into every 1L of salt-containing wastewater. The calcium-aluminum crystal is conveyed to a first dehydrator 10 by a first sludge pump 9 for sludge dehydration, clear liquid obtained by dehydration returns to the crystal reaction tank 5 for repeated treatment, and the dehydrated sludge is sent to a solid waste treatment center for treatment as common solid waste. And (3) enabling supernatant obtained by the precipitation reaction to enter a crystal reaction tank 5 of a crystal reaction unit 4 of the 2 nd crystal reaction unit for repeating the treatment process, standing for 60 minutes in the reaction, and controlling the pH value to be 13 to finally obtain clear liquid.
Because the pH of the clarified liquor is relatively high and contains a certain concentration of calcium ions or other alkaline earth metal ions, neutralization is required before discharge and the concentration of calcium ions or other alkaline earth metal ions in the wastewater is reduced. Therefore, the clarified liquid obtained in the above-mentioned treatment step is fed into the neutralization reactor 7, and the neutralizer: CO 22Acid gas, CO2The acid gas is used as purified flue gas, after neutralization reaction, the pH value of the clear liquid is adjusted to 7.5, and the acid gas flows into a neutralization precipitation tank 8 to form calcium carbonate precipitate. The clear liquid obtained in the neutralization precipitation tank 8 is the desalination wastewater sample 1, and the desalination wastewater sample is discharged or returned to the process for recycling.The obtained calcium carbonate sediment is merged into calcium-aluminum crystal sediment and is conveyed to a first dehydrator 10 by a first sludge pump 9 for sludge dehydration, clear liquid obtained by dehydration is returned to a crystal reaction tank 5 for repeated treatment, and the dehydrated sludge is merged into the sludge obtained in the previous step for dehydration and is sent to a solid waste treatment center for treatment.
After wastewater containing thousands of ppm of salt is treated, the water inlet of the treatment system, the clarified liquid after precipitation reaction and the clear liquid after neutralization reaction are respectively sampled and then subjected to component test, and the test results are shown in table 3. As can be seen from Table 3, for the wastewater containing salt of thousands of ppm, Cl in the inlet water is treated by the system-Reducing the concentration from 2000mg/L to 380mg/L in the clear liquid, adding Na in the water+The concentration is reduced from 2500mg/L to 450mg/L in clear liquid, and a better desalting effect is obtained.
TABLE 3
After wastewater containing tens of thousands of ppm of salt is treated, the water inlet of the treatment system, the clarified liquid after precipitation reaction and the clear liquid after neutralization reaction are respectively sampled and then subjected to component test, and the test results are shown in table 4. As can be seen from Table 4, even tens of thousands ppm of salt-containing wastewater can be pretreated by the system to achieve a better desalting effect.
TABLE 4
To sum up, this with the novel multistage crystallization of wastewater desalination deposits processing system that provides utilizes the crystallization precipitation effect of calcium aluminium crystal body, gets rid of salt in the waste water, and this system has energy saving and treatment cost, does not receive the influence of organic matter content in the water, can be used for advantages such as the preliminary treatment of waste water biochemical treatment. Therefore, the utility model effectively overcomes various defects in the prior art and has high industrial utilization value.
The above embodiments are merely illustrative of the principles and effects of the present invention, and are not to be construed as limiting the invention. Modifications and variations can be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (6)
1. The multi-stage crystallization precipitation treatment system for wastewater desalination is characterized in that a crystal reaction part (3), a neutralization reaction tank (7) and a neutralization precipitation tank (8) are sequentially arranged along the water inlet direction of saline wastewater, the crystal reaction part (3) comprises at least one crystal reaction unit (4), and the crystal reaction unit (4) is sequentially provided with a crystal reaction tank (5) and a crystal precipitation tank (6) along the water inlet direction of the saline wastewater; a water inlet of the crystal reaction tank (5) is externally connected with a calcium agent storage tank (13), an adjuvant storage tank (14) and an aluminum agent storage tank (15), and a water inlet of the neutralization reaction tank (7) is externally connected with a neutralizer storage tank (17); the sludge outlets of the crystal precipitation tank (6) and the neutralization precipitation tank (8) are sequentially externally connected with a first sludge pump (9) and a first dehydrator (10) along the sludge outlet direction, and the first dehydrator (10) is connected with the water inlet of the crystal reaction tank (5).
2. The multistage crystallization and precipitation treatment system for wastewater desalination according to claim 1, further comprising a heavy metal reaction tank (1) and a heavy metal precipitation tank (2), wherein the heavy metal reaction tank (1), the heavy metal precipitation tank (2) and the crystal reaction component (3) are sequentially arranged along the water inlet direction of the saline wastewater, a calcium agent storage tank (13) is externally connected to a water inlet of the heavy metal reaction tank (1), a sludge outlet of the heavy metal precipitation tank (2) is sequentially externally connected with a second sludge pump (11) and a second dehydrator (12) along the sludge outlet direction, and the second dehydrator (12) is further connected with a water inlet of the heavy metal reaction tank (1).
3. The multistage crystallization and precipitation treatment system for wastewater desalination according to claim 2, further comprising a flocculant storage tank (16), wherein the flocculant storage tank (16) is connected to the water inlet of the crystalline reaction tank (5) and the water inlet of the heavy metal reaction tank (1), respectively.
4. The multistage crystallization and precipitation treatment system for wastewater desalination according to claim 2, wherein a pH meter and a stirring paddle are arranged in the heavy metal reaction tank (1).
5. The multistage crystallization precipitation treatment system for wastewater desalination according to claim 1, wherein a pH meter is arranged in the neutralization reaction tank (7) and the crystal reaction tank (5).
6. The multistage crystallization and precipitation treatment system for wastewater desalination according to claim 1, wherein stirring paddles are arranged in the neutralization reaction tank (7) and the crystal reaction tank (5).
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