CN109293112B - Treatment method for recycling viscose fiber acid wastewater - Google Patents
Treatment method for recycling viscose fiber acid wastewater Download PDFInfo
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- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
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Abstract
The invention discloses a treatment method for recycling viscose fiber acid wastewater, which comprises the following steps: (1) collecting the viscose fiber acid wastewater to a raw water tank, and sequentially performing air stripping and/or stirring and filtering to remove colloidal substances and suspended substances in the viscose fiber acid wastewater, thereby reducing the turbidity of the wastewater and H2S、CS2And the like to obtain a light yellow pretreatment solution; (2) cooling, ultrafiltering and reverse osmosis the light yellow pretreatment liquid to obtain colorless reverse osmosis produced water and orange reverse osmosis concentrated water, adding activated carbon into the orange reverse osmosis concentrated water for adsorption and clarification, and removing COD (chemical oxygen demand) and the like in the orange reverse osmosis concentrated water to obtain colorless acidic concentrated water; (3) and evaporating and crystallizing the colorless acidic concentrated water to obtain recyclable acid liquor and sodium sulfate. The invention can realize the near zero discharge of the acid wastewater in the viscose fiber industry and the resource utilization of acid, salt and the like in the acid wastewater, and simultaneously realize the recycling of industrial water, thereby not only being green and environment-friendly, but also effectively saving the production cost of enterprises.
Description
Technical Field
The invention relates to a wastewater treatment method, in particular to a treatment method for recycling viscose fiber acid wastewater.
Background
At present, acid wastewater discharged by viscose fiber factories mainly comes from textile plants, acid stations and the like, and contains sulfuric acid, sodium sulfate, zinc sulfate, aluminum sulfate, carbon disulfide, hydrogen sulfide, soluble organic matters, suspended matters and the like. The more traditional processing mode is as follows: acid wastewater is discharged to a sewage treatment plant and is mixed with alkaline wastewater, the pH value of the mixed wastewater is adjusted to be alkalescent so as to remove zinc sulfate in the wastewater and generate zinc hydroxide solid precipitate, the wastewater containing a large amount of salt is subjected to two-stage treatment of physical and chemical treatment and biochemical treatment, and the supernatant of the treated wastewater is discharged. The traditional treatment method converts useful components in the acidic wastewater into salts which are not needed by viscose enterprises, and wastes valuable substances such as sulfuric acid, zinc sulfate and the like, and simultaneously wastes a large amount of water resources, so that additional consumption of enterprise resources and energy is caused.
Disclosure of Invention
The invention mainly aims to provide a treatment method for recycling viscose acid wastewater, thereby overcoming the defects in the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
the embodiment of the invention provides a treatment method for recycling viscose acid wastewater, which comprises the following steps:
a pretreatment step comprising: collecting viscose fiber acid wastewater to a raw water tank, and sequentially performing air stripping and/or stirring and more than one filtering treatment, thereby removing at least part of colloidal substances and suspended matters in the wastewater, reducing the turbidity and the acid gas content of the wastewater and obtaining a light yellow pretreatment solution;
a membrane concentration step comprising: sequentially cooling, ultrafiltering, reverse osmosis, activated carbon adsorption and clarifying the light yellow pretreatment solution to obtain colorless reverse osmosis produced water and colorless acidic concentrated water;
an evaporative crystallization step comprising: and (3) carrying out evaporation and crystallization treatment on the colorless acidic concentrated water to obtain recyclable acid liquor and sodium sulfate. In some more specific embodiments, the step of pre-treating specifically comprises: conveying the viscose fiber acid wastewater to a raw water tank by a pump for centralized collection, overflowing the viscose fiber acid wastewater into a stripping tank, overflowing the viscose fiber acid wastewater into a stirring tank after full aeration, conveying the viscose fiber acid wastewater to more than one acid-resistant filter for more than one filtering treatment after full stirring, and enabling the turbidity of the wastewater to meet the requirement of an ultrafiltration system on water inlet conditions to obtain a faint yellow pretreatment liquid; wherein, the acid-proof filter comprises any one or combination of a quartz sand filter, a one-stage or multi-stage microporous filter and a tow filter, and is not limited in this respect.
In some more specific embodiments, the membrane concentration step specifically comprises: and cooling the light yellow pretreatment liquid to 25-50 ℃ by using a cooler, then conveying the light yellow pretreatment liquid to an ultrafiltration membrane system for ultrafiltration, performing reverse osmosis on the obtained ultrafiltrate by using a reverse osmosis system to obtain colorless reverse osmosis produced water and orange reverse osmosis concentrated water, and then performing COD adsorption and clarification treatment on the orange reverse osmosis concentrated water by using activated carbon to obtain colorless acidic concentrated water.
In some specific embodiments, the treatment method for recycling viscose acid wastewater may further include: the COD in the acidic wastewater is adsorbed using activated carbon in any one of the pretreatment step, the membrane concentration step and the evaporative crystallization step. In some more specific embodiments, the evaporative crystallization step comprises: carrying out evaporative crystallization treatment on the colorless acidic concentrated water by adopting a thermal crystallization method or a cold crystallization method so as to extract sodium sulfate in the colorless acidic concentrated water; the temperature of the hot crystallization method is controlled to be above 32.8 ℃, sodium sulfate is separated out in a crystal water-free mode, the temperature of the cold crystallization method is controlled to be below 32.8 ℃, and the sodium sulfate is separated out in a mirabilite mode.
Compared with the prior art, the invention can realize near zero emission of acid wastewater in the viscose fiber industry and resource utilization of acid, salt and the like in the acid wastewater, and simultaneously realize industrial water recycling, thereby not only being green and environment-friendly, but also effectively saving the production cost of enterprises and improving the economic benefit of the enterprises.
Detailed Description
As described above, in view of the shortcomings of the prior art, the present inventors have made extensive studies and extensive practices to propose a technical solution of the present invention. The technical solutions of the present invention will be described clearly and completely below, and it should be apparent that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The treatment method for recycling the viscose acid wastewater provided by the embodiment of the invention comprises the following steps:
a pretreatment step comprising: collecting viscose fiber acid wastewater to a raw water tank, and sequentially performing air stripping and/or stirring and more than one filtering treatment, thereby removing at least part of colloidal substances and suspended matters in the wastewater, reducing the turbidity and the acid gas content of the wastewater and obtaining a light yellow pretreatment solution;
a membrane concentration step comprising: sequentially cooling, ultrafiltering, reverse osmosis, activated carbon adsorption and clarifying the light yellow pretreatment solution to obtain colorless reverse osmosis produced water and colorless acidic concentrated water;
an evaporative crystallization step comprising: and (3) carrying out evaporation and crystallization treatment on the colorless acidic concentrated water to obtain recyclable acid liquor and sodium sulfate. Further, the viscose acid waste water comprises any one or combination of more of substances such as sulfuric acid, sodium sulfate, zinc sulfate, aluminum sulfate and the like, the water temperature of the viscose acid waste water is 70-98 ℃, and the COD content is more than or equal to 1000 mg/L.
For example, the viscose acid wastewater may be, but is not limited to, scouring water from a spinning plant and acid station discharge wastewater, and the like.
Further, the viscose fiber acid wastewater of the invention has the following characteristics:
(1) after the raw water temperature of the acidic water is rapidly cooled from 90 ℃ to 25 ℃, the turbidity of the raw water cannot be greatly changed due to the change of the temperature, namely: the partial dissolved substances can not be separated out due to the temperature reduction.
(2) Standing raw water of the acidic water for 1-8 hours, wherein the turbidity is increased from about 10NTU to about 45NTU along with the time extension, but no precipitate exists; standing for about 24 hours, observing that no precipitate is still left at the bottom, and changing the raw water from a clear and transparent state to a dim and turbid state.
(3) After the raw water of the acidic water is kept stand for a long time, for example, the raw water is kept stand for about 48 hours, the bottom of the raw water is observed to have fine precipitates, the raw water is fully shaken to be changed into a dim turbid state, the raw water is still in the dim turbid state after being heated to the temperature of the raw water, and then the raw water is kept stand for a long time to generate blocky precipitates.
(4) The separation of superfine suspended matters is promoted by blowing off and stirring the raw water of the acidic water, and the turbidity of the liquid is increased in sequence; in addition, the turbidity of the stirred acidic wastewater is not obviously changed after standing for 1-8 hours, the liquid has no clarification effect in economically feasible clarification time (less than or equal to 8 hours), the clarification is increased to 24-48 hours, and the superfine precipitate can be seen at the bottom of the clarification tank, so that after stirring, the precipitation of the superfine suspended matters and the precipitated suspended matters has no obvious effect in economically feasible time (less than or equal to 8 hours). In some more specific embodiments, the step of pre-treating specifically comprises: conveying the viscose fiber acid wastewater to a raw water tank by a pump for centralized collection, overflowing into a stripping tank, fully aerating, overflowing to a stirring tank, fully stirring, conveying to more than one acid-resistant filter for more than one filtering treatment, and reducing the turbidity of the wastewater to less than or equal to 15NTU to obtain a faint yellow pretreatment solution.
Wherein, the acid-proof filter comprises any one or more of a quartz sand filter, a one-stage or multi-stage microporous filter and a tow filter, but is not limited to the above.
Further, the viscose fiber acid wastewater can be conveyed to a raw water tank by a pump for centralized collection, overflows into a stripping tank, and overflows into a stirring tank after sufficient aeration; stirring for a certain time, pumping to quartz sand filter, one-stage or multi-stage microporous filter, or acid-resistant filter such as tow filter, etc., and reducing turbidity to less than or equal to 15NTU to obtain yellowish pretreatment solution.
Further, the raw water pool, the stripping pool and the stirring pool are all acid-resistant water pools.
In some more specific embodiments, the step of pre-treating further comprises: the stripping tank is internally provided with a plurality of clapboards for reducing the back mixing of water flow and ensuring that the raw water stripping time is more than or equal to 0.5h, and the top of the stripping tank is provided with a gas collecting hood for collecting acid gas.
Further, the acid gas contains mainly H2S、CS2Moisture, etc.
In some more specific embodiments, the step of pre-treating further comprises: set up a plurality of baffles in the stirring pond for reduce the backmixing of rivers, and stirring pond top sets up a plurality of agitators, and guarantees that raw water stirring time is 0.5 ~ 6 h.
Wherein, a plurality of clapboards are arranged in the stripping tank, thereby reducing the back mixing of water flow as much as possible, ensuring that the stripping time of raw water is more than or equal to 0.5H, and dissolving H in water2S、CS2And the gas-collecting hood is arranged at the top of the stripping tank and used for collecting the acid gas.
And a plurality of baffles are arranged in the stirring tank, so that the back mixing of water flow is reduced as much as possible, and a plurality of stirrers are arranged above the tank, so that the stirring time of raw water is about 0.5-6 h.
Furthermore, the blowing-off tank can remove most of hydrogen sulfide and carbon disulfide dissolved in the acidic wastewater, so that the content of sulfide in the pretreatment liquid in the step (1) is greatly reduced, sulfur going to downstream reverse osmosis and an evaporative crystallizer is effectively reduced, the service life of the reverse osmosis membrane is greatly prolonged, and the heat transfer efficiency of the evaporative crystallizer is increased; the air blown into the pool has two functions: firstly, oxygen in the air can react with hydrogen sulfide to generate elemental sulfur; secondly, the air can carry out the dissolved hydrogen sulfide and carbon disulfide from the water; the air-water ratio in the stripping process is different, and the required stripping time is also different.
Furthermore, the filtration precision of the one-stage or multi-stage microporous filter is 1-10 μm, the filtration precision can be adjusted according to the turbidity requirement, the turbidity of the filtrate after the microporous filter is less than or equal to 15NTU, and the proper turbidity range can be adjusted according to the requirements of different ultrafiltration systems on water inlet conditions.
In some more specific embodiments, the membrane concentration step specifically comprises: cooling the light yellow pretreatment liquid to 25-50 ℃ by using a cooler to obtain pretreatment liquid with proper temperature, then conveying the pretreatment liquid to an ultrafiltration membrane system for ultrafiltration, performing reverse osmosis on the obtained ultrafiltrate by using a reverse osmosis system to obtain colorless reverse osmosis produced water and orange reverse osmosis concentrated water, and then performing COD (chemical oxygen demand) adsorption and clarification treatment on the orange reverse osmosis concentrated water by using activated carbon to obtain colorless acidic concentrated water.
Further, the position and the number of stages of the cooler are not limited, and it is sufficient that the pretreatment liquid reaches an appropriate temperature. For example, a cooler can be added in front of the raw water pool to exchange heat with colorless acidic concentrated water obtained by the membrane concentration unit, so that the heat of the raw water can be utilized, and if the temperature of the pretreatment liquid is still high, a primary cooler can be added after the pretreatment.
More specifically, the acidic wastewater is cooled to 25-50 ℃ by the pretreatment liquid through a cooler to obtain the pretreatment liquid with a proper temperature, wherein the proper temperature is a temperature suitable for membrane treatment. The temperature of the viscose acid wastewater is high, so that the viscose acid wastewater cannot directly enter a membrane separation system, and the acid wastewater is naturally cooled through a raw water tank, a stripping tank and a stirring tank, but the temperature is still high, so that a cooler is arranged in front of an ultrafiltration system for cooling.
Further, the ultrafiltration mode includes a cross flow mode or a dead end mode, wherein the adopted ultrafiltration membrane element includes a tubular type, a plate type, a disc type, a roll type or a capillary type membrane element, and is not limited thereto.
Further, the ultrafiltration system comprises a UF water inlet tank, a UF water inlet pump, a UF cartridge filter, a UF membrane unit, a UF circulating pump and a UF water production tank which are communicated through a pipeline; the cooled light yellow pretreatment liquid sequentially passes through an UF water inlet tank, an UF water inlet pump and an UF cartridge filter and then enters an UF membrane unit, and after being filtered by an ultrafiltration membrane, larger molecular suspended matters are separated, so that ultrafiltrate required by reverse osmosis water inlet is obtained.
Furthermore, the reverse osmosis system comprises a security filter, a reverse osmosis high-pressure pump, an RO membrane unit, an RO water production tank and an RO concentrated water tank which are communicated through pipelines, ultrafiltrate sequentially passes through the security filter and the reverse osmosis high-pressure pump and then enters the RO membrane unit (comprising one section or a plurality of sections of RO reverse osmosis membrane stacks), the obtained colorless reverse osmosis water (reverse osmosis water) enters the RO water production tank, and orange yellow reverse osmosis concentrated water (RO concentrated water) enters the RO concentrated water tank.
Furthermore, the operating pressure of the reverse osmosis is controlled to be 5-16 MPaG, and the final salt concentration of the concentrated water is 110000-300000 mg/L. The operating pressure of the reverse osmosis system which meets the economical and feasible requirements can be further improved, higher salt concentration can be obtained, the load of an evaporative crystallization device can be reduced due to the high end salt concentration, and the primary investment cost of equipment and the operating cost of the device can be reduced.
In some more specific embodiments, the membrane concentration step further comprises: adding activated carbon into the orange-yellow reverse osmosis concentrated water for adsorption for more than or equal to 0.25h, thereby removing COD in the orange-yellow reverse osmosis concentrated water. In the adsorption process, a stirrer can be added for stirring, the adsorption time of the activated carbon can be increased or decreased according to the carbon adsorption effect, and COD is removed in the process.
In some more specific embodiments, the membrane concentration step further comprises: after the operation of adsorbing COD in the orange-yellow reverse osmosis concentrated water by using activated carbon is completed, the used activated carbon is subjected to regeneration treatment, so that the activated carbon is used for multiple times.
In the invention, the COD adsorption and removal by the activated carbon has the following functions and characteristics:
(1) removing COD can prevent downstream evaporative crystallizer scaling and reduce the boiling point rise of the solution. If the downstream evaporation crystallizer is scaled, the downstream evaporation crystallizer can be cleaned by proper alkali liquor.
(2) Removing COD to prevent color enrichment and ensure the quality of viscose fiber products.
Further, the invention selects the activated carbon at the reverse osmosis concentrated water for the reasons of adsorption effect and economy, and does not exclude the possibility of adding the activated carbon at other positions. For example, in some embodiments, the treatment method for recycling viscose fiber acid wastewater further comprises: the COD in the acidic wastewater is adsorbed using activated carbon in any one of the pretreatment step, the membrane concentration step and the evaporative crystallization step.
Further, the clarification tank adopted in the clarification treatment is an acid-resistant water tank, the bottom of the clarification tank is provided with a mud scraper, the mud scraper can be operated intermittently and is used for collecting sediments at the bottom of the tank to the center of the bottom of the tank in time, and the clarification tank is operated intermittently or continuously. Wherein, the intermittent operation can ensure that the acid wastewater is completely kept still, and the necessary time for clarification is determined according to the clarification effect and the economical efficiency no matter the continuous operation or the intermittent operation is carried out.
In some more specific embodiments, the evaporative crystallization step comprises: carrying out evaporative crystallization treatment on the colorless acidic concentrated water by adopting a thermal crystallization method or a cold crystallization method so as to extract sodium sulfate in the colorless acidic concentrated water; the temperature of the hot crystallization method is controlled to be above 32.8 ℃, sodium sulfate is separated out in a crystal water-free mode, the temperature of the cold crystallization method is controlled to be below 32.8 ℃, and the sodium sulfate is separated out in a mirabilite mode.
Further, the evaporation crystallization treatment mode includes, but is not limited to, MVR evaporation, multiple-effect evaporation, or multi-stage vacuum flash evaporation.
The invention realizes the near zero emission and resource utilization of the acidic wastewater in the viscose industry, realizes the recycling of industrial water while recovering acid and salt in the acidic wastewater, brings good economic benefit to production enterprises while realizing green production, and has practical and guiding significance for the treatment work of recycling waste of the acidic wastewater in the viscose industry. The technical solution of the present invention will be described in more detail with reference to some more specific examples.
The acidic wastewater treated by the following embodiment is fiber washing water which is discharged from a spinning and practicing workshop of a viscose fiber factory and is carried with an acid bath, the water temperature of the discharge position is 70-98 ℃ after the fibers are cut off, the discharge position mainly contains sulfuric acid, sodium sulfate, zinc sulfate, aluminum sulfate, carbon disulfide, hydrogen sulfide, soluble organic matters, suspended matters and the like, and the COD content is more than or equal to 1000 mg/L.
The wastewater treatment method employed in the following examples included: collecting the viscose fiber acid wastewater into a raw water tank, overflowing the viscose fiber acid wastewater into a blow-off tank (blow-off for 2 hours), then overflowing the viscose fiber acid wastewater into a stirring tank (stirring for 2 hours), then conveying the viscose fiber acid wastewater into a quartz sand filter, a primary microporous filter (the filtration precision is 10 microns) and a secondary microporous filter (the filtration precision is 1 micron), and filtering and removing suspended matters to reduce the content and turbidity of the suspended matters in the acid water; then the water produced by the ultrafiltration membrane enters an RO reverse osmosis system, the fresh water produced by the first, second and third sections of reverse osmosis enters an RO water producing tank, and the concentrated water produced by the third section of reverse osmosis enters an RO concentrated water tank; and (3) the RO concentrated water passes through an activated carbon adsorption tank (stirred for 0.5h), activated carbon powder with the mass of 6/10000-15/10000 (which is about equal to 2/10000-5/10000 of the mass of the raw water) of the concentrated solution is added, COD is removed, the RO concentrated water is fully kept stand and clarified, then the RO concentrated water enters an evaporation and crystallization device, and the recyclable acid liquor and sodium sulfate are obtained through the evaporation and crystallization device. The principle of the preprocessing unit is as follows: the method comprises the following steps that substances such as dissolved fibers, semi-fibers and insoluble fine solid particles in the acidic wastewater are violently collided in the stripping and stirring processes, a part of the substances can form large micelles to be separated out from a dissolved state, a part of the substances are subjected to certain oxidation reaction in the presence of oxygen to form large suspended solids, hydrogen sulfide and carbon disulfide in the wastewater are stripped out, the separated micelles and the generated suspended solids are intercepted through a quartz sand filter and a microporous filter, and the turbidity of the wastewater and the content of the hydrogen sulfide and the content of the carbon disulfide in the wastewater are reduced. The principle of ultrafiltration is: under certain pressure, the acid wastewater is filtered by an ultrafiltration membrane to separate out larger molecular suspended matters, and the acid wastewater after ultrafiltration meets the requirement of reverse osmosis water inlet. The principle of reverse osmosis is: by utilizing the reverse osmosis membrane, certain pressure is applied to the acid water inlet side, so that water molecules penetrate through the reverse osmosis membrane to enter the water production side, and a very small amount of substances except the water molecules penetrate through the reverse osmosis membrane. The principle of activated carbon adsorption: the porous structure of the active carbon is used for adsorbing soluble organic matters. The principle of evaporative crystallization: evaporating water to make sodium sulfate in the solution supersaturated and separated out, and obtaining recyclable acid liquor and sodium sulfate.
Example 1: after the acid wastewater at the temperature of 70-98 ℃ is collected into a raw water pool, overflowing the acid wastewater into a stripping pool, taking out hydrogen sulfide and carbon disulfide dissolved in the acid wastewater by air blown into the water, stripping for 2h, then overflowing the acid wastewater into a stirring pool, promoting the separation of suspended matters by stirring, and stirring for 2h to increase the turbidity from 10NTU to 50 NTU; and then conveying the wastewater to a quartz sand filter and a one-stage or multi-stage microporous filter by a pump to remove solid suspended matters and small micelles, reducing the turbidity of the acidic wastewater from 50NTU to below 10NTU, and reducing the total amount of the dissolved hydrogen sulfide and carbon disulfide from 4-12 mg/L to below 0.3 mg/L.
Example 2: after the acid wastewater at the temperature of 70-98 ℃ is collected into a raw water pool, overflowing the acid wastewater into a stripping pool, taking out hydrogen sulfide and carbon disulfide dissolved in the acid wastewater by air blown into the water, stripping for 2 hours, then overflowing the acid wastewater into a stirring pool, promoting the separation of suspended matters by stirring, stirring for 1 hour, and increasing the turbidity from 10NTU to 50 NTU; and then conveying the wastewater to a quartz sand filter and a one-stage or multi-stage microporous filter by a pump to remove solid suspended matters and small micelles, reducing the turbidity of the acidic wastewater from 50NTU to below 10NTU, and reducing the total amount of the dissolved hydrogen sulfide and carbon disulfide from 4-12 mg/L to below 0.3 mg/L.
Example 3: after the acid wastewater at the temperature of 70-98 ℃ is collected into a raw water pool, overflowing into a stripping pool, taking out hydrogen sulfide and carbon disulfide dissolved in the acid wastewater by air blown into water, stripping for 2h, then overflowing into a stirring pool, promoting the separation of suspended matters by stirring, stirring for 2.5h, and increasing the turbidity from 10NTU to 50 NTU; and then conveying the wastewater to a quartz sand filter and a one-stage or multi-stage microporous filter by a pump to remove solid suspended matters and small micelles, reducing the turbidity of the acidic wastewater from 50NTU to below 10NTU, and reducing the total amount of the dissolved hydrogen sulfide and carbon disulfide from 4-12 mg/L to below 0.3 mg/L.
Example 4: after the acidic wastewater is pretreated and ultrafiltered, the obtained 200L of ultrafiltration produced water is subjected to a concentration experiment by three-stage reverse osmosis of 6MPaG, 8MPaG and 10MPaG, and the total salt content is concentrated to 205000 mg/L-240000 mg/L by 60000 mg/L-85000 mg/L through three stages; the water yield of each section of the three-section concentration treatment is more economic and reasonable, the reverse osmosis equipment investment is saved, the final salt concentration is high, the load of an evaporative crystallization device is reduced, and the one-time investment cost of the equipment and the operation cost of the device are reduced.
Example 5: after the acidic wastewater is pretreated, ultrafiltered and subjected to reverse osmosis, activated carbon powder is added into the obtained reverse osmosis concentrated solution, the mixture is stirred for 30min, the removal amount of COD is 600-1000 mg/g, 6/10000-15/10000 (which is about 2/10000-5/10000 of the mass of raw water) with the mass of the concentrated solution is added, and the colored COD and part of the colorless COD can be removed completely.
Comparative example 1: collecting the acid water with the temperature of 70-98 ℃ to a raw water pool, and then carrying out no treatment, wherein the turbidity is 10NTU, and the total amount of the dissolved hydrogen sulfide and carbon disulfide is 4-12 mg/L.
Comparative example 2: and collecting the acid water at the temperature of 70-98 ℃, directly standing for 6 hours without stripping and stirring, wherein the turbidity of the acid wastewater is 40-50 NTU, and the total amount of the dissolved hydrogen sulfide and carbon disulfide is 4-12 mg/L.
Comparative example 3: collecting the acid water at the temperature of 70-98 ℃, then stripping for 1h, directly standing for 4h without stirring, wherein the turbidity of the acid wastewater is about 40-50 NTU, and the total amount of the dissolved hydrogen sulfide and carbon disulfide is not more than 0.3-1.5 mg/L.
Comparative example 4: collecting acid water with the temperature of 70-98 ℃, stirring for 1.5h, directly standing for 4h, not blowing off, 40-50 NTU of acid wastewater, and the total amount of dissolved hydrogen sulfide and carbon disulfide being 2-4.5 mg/L.
Comparative example 5: referring to the previous embodiment, after the pretreatment and ultrafiltration of the acidic wastewater, the obtained 200L of ultrafiltration produced water is concentrated by 5MPaG first-stage reverse osmosis, and the total salt content is concentrated from 60000 mg/L-85000 mg/L to 110000 mg/L-135000 mg/L; the concentration of the final salt in the concentrated water treated in the first section is lower, the load of a subsequent evaporative crystallization device is large, and the one-time investment cost of equipment and the operation cost of the device are large.
Comparative example 6: referring to the previous embodiment, after the pretreatment and ultrafiltration of the acidic wastewater, the obtained 200L of ultrafiltration produced water is concentrated by 6MPaG first-stage reverse osmosis, and the total salt content is concentrated from 60000 mg/L-85000 mg/L to 140000 mg/L-170000 mg/L; the concentration of the final salt in the concentrated water treated in the first section is lower, the load of a subsequent evaporative crystallization device is large, and the one-time investment cost of equipment and the operation cost of the device are large.
Comparative example 7: referring to the previous embodiment, after the pretreatment and ultrafiltration of the acidic wastewater, 200L of ultrafiltration produced water is concentrated by 7MPaG first-stage reverse osmosis, and the total salt content is concentrated from 60000 mg/L-85000 mg/L to 170000 mg/L-190000 mg/L; the concentration of the salt at the end point of the concentrated water treated in the first section is slightly lower, the load of a subsequent evaporative crystallization device is larger, the one-time investment cost of equipment and the operation cost of the device are larger, and the investment of reverse osmosis equipment is larger.
Comparative example 8: referring to the previous embodiment, after the pretreatment and ultrafiltration of the acidic wastewater, 200L of ultrafiltration produced water is subjected to a concentration experiment by 8MPaG first-stage reverse osmosis, and the total salt amount is concentrated from 60000mg/L to 85000mg/L to 185000mg/L to 205000 mg/L; the concentration of the salt at the end point of the concentrated water treated in the first section is slightly lower, the load of a subsequent evaporative crystallization device is larger, the one-time investment cost of equipment and the operation cost of the device are larger, and the investment of reverse osmosis equipment is larger.
Comparative example 9: referring to the previous embodiment, after the pretreatment and ultrafiltration of the acidic wastewater, 200L of ultrafiltration produced water is concentrated by 9MPaG first-stage reverse osmosis, and the total salt content is concentrated from 60000mg/L to 85000mg/L to 195000mg/L to 215000 mg/L; the concentration of the salt at the end point of the concentrated water treated in the first section is slightly lower, the load of a subsequent evaporative crystallization device is larger, the one-time investment cost of equipment and the operation cost of the device are larger, and the investment of reverse osmosis equipment is larger.
Comparative example 10: referring to the previous embodiment, after the pretreatment and ultrafiltration of the acidic wastewater, 200L of ultrafiltration produced water is concentrated by 10MPaG first-stage reverse osmosis, and the total salt content is concentrated from 60000 mg/L-85000 mg/L to 205000 mg/L-240000 mg/L; the concentration of the salt at the end point of the concentrated water treated in the first section is high, the load of a subsequent evaporative crystallization device can be reduced, the primary investment cost of equipment and the operation cost of the device are reduced, but the investment of reverse osmosis equipment is large.
Comparative example 11: referring to the embodiment, after the pretreatment and ultrafiltration of the acidic wastewater, the same activated carbon powder is added into the ultrafiltration product water and stirred for 30min, and the removal amount of COD is 200 mg/g-300 mg/g.
It should be noted that, the technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. The treatment method for recycling the viscose acid wastewater is characterized in that the viscose acid wastewater comprises sulfuric acid, sodium sulfate, zinc sulfate and aluminum sulfate, the water temperature of the viscose acid wastewater is 70-98 ℃, and the COD content is more than or equal to 1000mg/L, and the treatment method comprises the following steps:
a pretreatment step comprising: the method comprises the steps of conveying viscose acid wastewater to a raw water tank by a pump for centralized collection, enabling the viscose acid wastewater to enter a stripping tank in an overflow mode, after full aeration, enabling the viscose acid wastewater to overflow to a stirring tank, after full stirring, conveying the viscose acid wastewater to more than one acid-resistant filter for more than one time of filtration treatment, thereby removing at least partial colloidal substances and suspended substances in the wastewater, reducing the turbidity of the wastewater and the content of acid gas, enabling the turbidity of the wastewater to meet the requirement of an ultrafiltration system on the water inlet condition, obtaining faint yellow pretreatment liquid, wherein the acid gas mainly contains H2S、CS2And water vapor, wherein a plurality of clapboards are arranged in the stripping pool to reduce the back mixing of water flow and ensure the raw waterThe stripping time is more than or equal to 0.5h, and a gas-collecting hood is arranged at the top of the stripping tank and used for collecting acid gas; a plurality of partition plates are arranged in the stirring pool and used for reducing back mixing of water flow, a plurality of stirrers are arranged above the stirring pool, and raw water stirring time is guaranteed to be 0.5-6 hours;
a membrane concentration step comprising: cooling the faint yellow pretreatment liquid to 25-50 ℃ through a cooler, then conveying the faint yellow pretreatment liquid to an ultrafiltration membrane system for ultrafiltration, performing reverse osmosis on the obtained ultrafiltrate through a reverse osmosis system, controlling the operating pressure of the reverse osmosis to be 5-16 MPaG, and controlling the final salt concentration of concentrated water to be 110000-300000 mg/L to obtain colorless reverse osmosis produced water and orange reverse osmosis concentrated water, then adding activated carbon into the orange reverse osmosis concentrated water for adsorption for more than or equal to 0.25h to remove COD (chemical oxygen demand) in the orange reverse osmosis concentrated water, and then performing clarification treatment to obtain colorless acidic concentrated water;
an evaporative crystallization step comprising: and (2) carrying out evaporation crystallization treatment on the colorless acidic concentrated water by adopting a thermal crystallization method or a cold crystallization method, wherein the temperature of the thermal crystallization method is controlled to be above 32.8 ℃, sodium sulfate is separated out in a crystal water-free mode, the temperature of the cold crystallization method is controlled to be below 32.8 ℃, and the sodium sulfate is separated out in a mirabilite mode, so that the sodium sulfate in the sodium sulfate is extracted, and the recyclable acid liquor is obtained.
2. The viscose fiber acid wastewater resource utilization treatment method according to claim 1, characterized in that: the acid-proof filter comprises one or more of quartz sand filter, one-stage or multi-stage microporous filter and tow filter.
3. The viscose fiber acid wastewater resource utilization treatment method according to claim 1, characterized in that: the raw water pool, the stripping pool and the stirring pool are acid-resistant water pools.
4. The viscose fiber acid wastewater resource utilization treatment method according to claim 1, characterized in that: the ultrafiltration mode comprises a cross flow or dead end mode, wherein the adopted ultrafiltration membrane element comprises a tubular, plate, disc, roll or capillary membrane element.
5. The viscose fiber acid wastewater resource utilization treatment method according to claim 1, characterized in that: the ultrafiltration membrane system comprises a UF water inlet tank, a UF water inlet pump, a UF security filter, a UF membrane unit, a UF circulating pump and a UF water production tank which are communicated through a pipeline; the cooled light yellow pretreatment liquid sequentially passes through an UF water inlet tank, an UF water inlet pump and an UF cartridge filter and then enters an UF membrane unit, so that ultrafiltrate required by reverse osmosis water inlet is obtained.
6. The viscose fiber acid wastewater resource utilization treatment method according to claim 1, characterized in that: the reverse osmosis system comprises a security filter, a reverse osmosis high-pressure pump, an RO membrane unit, an RO water production tank and an RO concentrated water tank which are communicated through pipelines, ultrafiltrate sequentially passes through the security filter and the reverse osmosis high-pressure pump and then enters the RO membrane unit, obtained colorless reverse osmosis water production enters the RO water production tank, and orange yellow reverse osmosis concentrated water enters the RO concentrated water tank.
7. The viscose fiber acid wastewater resource utilization treatment method according to claim 1, further comprising the following steps: and after the operation of adsorbing COD in the orange-yellow reverse osmosis concentrated water by using activated carbon is finished, performing regeneration treatment on the used activated carbon.
8. The viscose fiber acid wastewater resource utilization treatment method according to claim 1, characterized in that: the clarification tank that adopts in the clarification treatment is the acid-proof water pond, the clarification tank bottom is provided with mud scraper for in time collect pond bottom precipitate to pond bottom center, and the clarification tank is intermittent operation or continuous operation.
9. The viscose fiber acid wastewater resource utilization treatment method according to claim 1, further comprising the following steps: the COD in the acidic wastewater is adsorbed by using activated carbon in any one of the pretreatment step and the evaporative crystallization step.
10. The viscose fiber acid wastewater resource utilization treatment method according to claim 1, characterized in that: the evaporation crystallization treatment mode comprises MVR evaporation, multiple-effect evaporation or multi-stage vacuum flash evaporation.
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| CN110054313A (en) * | 2019-06-10 | 2019-07-26 | 新疆中泰创新技术研究院有限责任公司 | A kind of viscose rayon acid waste water preprocess method |
| CN112573745B (en) * | 2020-11-23 | 2023-02-24 | 南京钛净流体技术有限公司 | SCR catalyst regeneration pickling wastewater treatment method |
| CN113058424A (en) * | 2021-03-26 | 2021-07-02 | 新疆中泰创新技术研究院有限责任公司 | Method and system for treating waste gas generated in production of viscose fibers containing hydrogen sulfide and carbon disulfide |
| CN113860669A (en) * | 2021-11-10 | 2021-12-31 | 广州兰德环保资源科技有限公司 | Method for recycling cellulose ether production wastewater |
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