CN107285536B - Treatment and utilization method of coal chemical industry sewage and wastewater - Google Patents
Treatment and utilization method of coal chemical industry sewage and wastewater Download PDFInfo
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Abstract
The invention discloses a method for treating and utilizing coal chemical industry sewage and wastewater, which comprises the steps of respectively treating production wastewater and production wastewater to obtain product salt and available fresh water, wherein the production wastewater is wastewater which is not polluted by industrial materials; the production sewage is sewage polluted by industrial materials. Through the technical scheme, on one hand, the production amount of miscellaneous salt is greatly reduced, the saleable product salt is produced, on the other hand, the amount of discharged crystal tail liquid is greatly reduced, and simultaneously, the regenerated water which is desalted fresh water is produced, so that the regenerated water can be used for a circulating cooling system, the concentration ratio of the circulating cooling system is improved, the water supplement amount is reduced, and the water resource is saved.
Description
Technical Field
The invention relates to the technical field of treatment of coal chemical industry sewage and wastewater, in particular to a method for treating and utilizing coal chemical industry sewage and wastewater.
Background
Generally, no discharged wastewater is received by a water body in the area of the coal chemical industry enterprise or the influence of the water environment caused by the discharged wastewater is hard to bear, so that the coal chemical industry enterprise is required to implement zero discharge or near zero discharge of the wastewater. From the practical operation effect of the coal chemical industry enterprises which implement zero discharge of wastewater, the following outstanding problems exist: (1) a large amount of miscellaneous salts are generated, solid salts generated by a crystallization unit in the prior art are miscellaneous salts, comprise various components such as sodium chloride, sodium sulfate, calcium carbonate and the like, the sodium chloride and the sodium sulfate in the solid salts can not be effectively utilized, the miscellaneous salts need to be treated by referring to hazardous wastes, the treatment cost is very high, generally more than 2000 yuan/ton, and the treatment cost reaches more than thousands of yuan in one year; (2) the discharge amount of tail liquid is large, because the solubility of nitrate is very high, nitrate crystals are difficult to generate, the concentration of nitrate radicals in the crystallization mother liquid is continuously increased, the crystallization process is influenced, the nitrate radicals must be discharged out of a system in a mode of discharging the crystallization tail liquid, the discharge amount of the tail liquid is large, the scale of required storage facilities is large, and the investment is high; (3) the unreasonable treatment depth of the reclaimed water causes the water use imbalance of the reclaimed water in different seasons. The existing coal chemical plant reclaimed water is mostly provided with two grades of common reclaimed water and high-quality reclaimed water, wherein the common reclaimed water is not desalted and is used for replenishing water of a circulating cooling system; the high-quality reclaimed water desalination is used for water replenishing of a circulating cooling system and other production water units, but the amount of the replenished water of the circulating cooling system is small in winter, common reclaimed water is difficult to use up, and a large-volume storage facility needs to be arranged for storage; in addition, due to the requirement of near-zero discharge of wastewater, from the viewpoint of inorganic salt material balance, fresh water is brought in and inorganic salts generated in the production process also need to be removed through crystallization, so that the scale of the desalting facility becomes large.
Therefore, a method for effectively utilizing sodium chloride and sodium sulfate in the coal chemical industry, reducing the yield of miscellaneous salt and the discharge amount of tail liquid and improving the treatment depth of the reclaimed water is urgently needed.
Disclosure of Invention
The invention aims to provide a method for treating and utilizing coal chemical industry sewage and wastewater, which comprises the following steps:
(1) carrying out first softening treatment on the production wastewater to obtain first softened water with the hardness not more than 0.04 meq/L;
(2) carrying out first concentration treatment on the first softened water obtained in the step (1) to obtain first concentrated fresh water and first concentrated water with the total salt content higher than 200g/L, and feeding the first concentrated fresh water into the reclaimed water recycling system;
(3) carrying out first crystallization treatment on the first concentrated water obtained in the step (2) to obtain first crystallized fresh water, first crystallized tail liquid and product salt, and feeding the first crystallized fresh water into the reclaimed water recycling system;
(4) mixing the production sewage with the first crystallization tail liquid, and then carrying out denitration and COD reduction treatment to obtain effluent with the total nitrogen content of less than 10mg/L, COD and less than 60 mg/L;
(5) performing second softening treatment on the effluent obtained in the step (4) to obtain second softened water with the hardness lower than 1.5 meq/L;
(6) performing second concentration treatment on the second softened water obtained in the step (5) to obtain second concentrated fresh water and second concentrated water with the total salt content higher than 200g/L, and feeding the second concentrated fresh water into the reclaimed water recycling system;
(7) carrying out second crystallization treatment on the second concentrated water obtained in the step (6) to obtain second crystallized fresh water, second crystallized tail liquid and miscellaneous salts, feeding the second crystallized fresh water into the reclaimed water recycling system, recycling at least one part of the second crystallized tail liquid as the feed for denitration and COD reduction treatment in the step (4), and feeding the rest second crystallized tail liquid into a tail liquid storage pool;
wherein the production wastewater is wastewater which is not polluted by industrial materials; the production sewage is sewage polluted by industrial materials.
Through the technical scheme, the invention has the following technical effects:
(1) through carrying out processing and crystallization respectively to production waste water and production sewage, on the one hand the yield of miscellaneous salt that has significantly reduced has reduced follow-up processing expense, and on the other hand can effectively utilize production waste water, produces sodium chloride product salt and sodium sulfate product salt.
(2) Through carrying out denitration and COD reduction treatment and concentrated treatment to production sewage to greatly reduced the outer crystallization tail liquid volume of arranging, reduced the volume of storage facility.
(3) Through handling production waste water and production sewage, the reclaimed water that produces is desalination fresh water, belongs to high-quality reclaimed water, can reuse in circulative cooling system, has reduced the capacity requirement of reclaimed water storage facility, has improved circulative cooling system's concentration rate simultaneously, reduces the moisturizing volume, has practiced thrift the water resource.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic flow diagram of one embodiment of the process of the present invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The invention aims to provide a method for treating and utilizing coal chemical industry sewage and wastewater, which comprises the following steps:
(1) carrying out first softening treatment on the production wastewater to obtain first softened water with the hardness not more than 0.04 meq/L;
(2) carrying out first concentration treatment on the first softened water obtained in the step (1) to obtain first concentrated fresh water and first concentrated water with the total salt content higher than 200g/L, and feeding the first concentrated fresh water into the reclaimed water recycling system;
(3) carrying out first crystallization treatment on the first concentrated water obtained in the step (2) to obtain first crystallized fresh water, first crystallized tail liquid and product salt, and feeding the first crystallized fresh water into the reclaimed water recycling system;
(4) mixing the production sewage with the first crystallization tail liquid, and then carrying out denitration and COD reduction treatment to obtain effluent with the total nitrogen content of less than 10mg/L, COD and less than 60 mg/L;
(5) performing second softening treatment on the effluent obtained in the step (4) to obtain second softened water with the hardness lower than 1.5 meq/L;
(6) performing second concentration treatment on the second softened water obtained in the step (5) to obtain second concentrated fresh water and second concentrated water with the total salt content higher than 200g/L, and feeding the second concentrated fresh water into the reclaimed water recycling system;
(7) carrying out second crystallization treatment on the second concentrated water obtained in the step (6) to obtain second crystallized fresh water, second crystallized tail liquid and miscellaneous salts, feeding the second crystallized fresh water into the reclaimed water recycling system, recycling at least one part of the second crystallized tail liquid as the feed for denitration and COD reduction treatment in the step (4), and feeding the rest second crystallized tail liquid into a tail liquid storage pool;
wherein the production wastewater is wastewater which is not polluted by industrial materials; the production sewage is sewage polluted by industrial materials.
According to the process of the invention, in step (1), the process wastewater is an industrial wastewater which is not contaminated or slightly contaminated and has a slightly increased water temperature, and the process wastewater of the invention can be various industrial wastewater which is not contaminated or has a slightly increased water temperature by process materials, in particular a process wastewater which is not contaminated by heavy metals, such as fresh water desalination wastewater and/or recycle system wastewater.
According to the method provided by the invention, when the production wastewater comprises wastewater discharged by a circulating system, the total salt content in the wastewater discharged by the circulating cooling system is low, in order to improve the treatment efficiency, preferably, the wastewater discharged by the circulating system is subjected to wastewater pre-concentration treatment to obtain pre-concentrated fresh water and pre-concentrated water with the total salt content higher than 6g/L, and then the obtained pre-concentrated water is subjected to the treatment of the step (1), so that the treatment efficiency can be effectively improved, and the economic benefit is further improved.
According to the present invention, in the step (1), the first softening treatment may be a softening treatment which is conventional in the art, and the production wastewater contains a large amount of cations and anions, wherein the cations generally include Na+、K+、Ca2+、Mg2+The anion typically comprises HCO3 -、Cl-、SO4 2-、NO3 -To avoid Ca2+And Mg2+Scaling in subsequent treatments such as concentration treatment while satisfying the requirement of the crystallization treatment of step (3) on wasteThe first softening treatment preferably includes: carrying out agent softening treatment on the production wastewater to obtain agent softening wastewater and chemical sludge; carrying out ion exchange softening treatment on the obtained medicament softening wastewater to obtain first softened water; and then, the obtained first softened water is subjected to the treatment of the step (2).
Wherein the ion exchange softening treatment comprises the step of regenerating ion exchange resin to obtain ion exchange regeneration wastewater, and the obtained ion exchange regeneration wastewater can be used as the feed for the denitration and COD reduction treatment in the step (4).
According to the process of the present invention, in step (3), the crystallization treatment is well known to those skilled in the art, and can be classified into cooling crystallization, evaporative crystallization or salting-out crystallization, and the present invention employs evaporative crystallization, which can employ conventional apparatuses in the art, such as forced external circulation type evaporative crystallizer developed by Swenson corporation in America, in order to obtain sodium chloride and sodium sulfate meeting the salt purity requirement of the commercial product, preferably, the conditions of the crystallization of the present invention include: controlling the discharge amount of the first crystallization tail liquid to control the nitrate concentration in the crystallization mother liquid to be below the saturated concentration, and respectively carrying out sodium chloride crystallization at 40-50 ℃ and sodium sulfate crystallization at 85-95 ℃.
According to the method, the production sewage in the step (4) is the wastewater polluted by industrial materials, wherein the industrial materials, the intermediate products, the byproducts and the pollutants generated in the production process are lost along with water; the production wastewater can be at least one selected from low-concentration production wastewater, high-concentration production wastewater and coal gasification wastewater, wherein the low-concentration production wastewater is the production wastewater with the COD concentration lower than 600mg/L, and the high-concentration production wastewater is the production wastewater with the COD concentration higher than 1800 mg/L.
According to the method, when the production wastewater comprises coal gasification wastewater, the coal gasification wastewater contains a large amount of cations and anions, has high salt content and high hardness and ammonia nitrogen concentration, and contains Ca2+、Mg2+、NO3 -Has adverse effects on the subsequent concentration and crystallization processes. To avoid Ca in the gasified sewage2+、Mg2+And (3) scaling in the subsequent treatment, pre-softening the coal gasification wastewater to obtain pre-softened water with the hardness of less than 2.0meq/L, and then performing the treatment of the step (4) on the obtained pre-softened water.
Wherein, the pre-softening treatment and/or the second softening treatment can adopt a softening method well known by a person skilled in the art, such as a medicament softening treatment, and the medicament used in the medicament softening treatment can be selected from Ca (OH)2、Na2CO3And NaOH.
According to the method of the present invention, in the step (4), the denitration and COD reduction treatment is at least one selected from the group consisting of an activated sludge treatment, an ozone oxidation treatment and a biofilm treatment. The activated sludge treatment is the treatment of sludge-like flocs formed by the proliferation of aerobic microorganisms after a period of time by continuously introducing air into the wastewater. The biofilm treatment belongs to a method of aerobic biological treatment, and can be divided into a biological filter, a biological rotating disk, a contact oxidation method and a biological fluidized bed according to different devices. Industrial wastewater contains a large amount of ammonia nitrogen substances and organic matters, and the removal treatment of the nitrogen substances and the organic matters generally adopts the comprehensive treatment of denitration treatment and COD (chemical oxygen demand) reduction treatment, wherein the nitrogen substances comprise ammonia nitrogen, nitrate and amine substances, and the removal of the nitrate is well known by the technical personnel in the field, such as denitrification treatment; removing ammonia nitrogen and amine substances by adopting comprehensive treatment of nitrification and denitrification, namely converting the ammonia nitrogen and the amine substances into nitrate, and then performing denitrification treatment on the obtained nitrate; the COD reduction treatment comprises the reduction of organic matters which are easy to be biochemically generated and organic matters which are difficult to be biochemically generated, and is well known by the technical personnel in the field, for example, the removal of the organic matters which are easy to be biochemically generated can adopt carbonization treatment, and the carbonization treatment is a process that microorganisms degrade the organic matters by using oxygen; the organic matters which are difficult to be biochemically treated can be degraded into organic matters which are easy to be biochemically treated by ozone oxidation treatment, and then the organic matters which are easy to biochemically treated are degraded by carbonization treatment. The activated sludge treatment and/or the biomembrane treatment can simultaneously realize the aims of denitration, reduction of easily biochemical COD and nitrification, a concrete pool is generally designed according to water quality and water quantity, a denitrification treatment unit, a carbonization treatment unit and a nitrification treatment unit are sequentially arranged, the three treatment units adopt an activated sludge method and/or a biomembrane treatment method, the denitrification treatment unit is set to be in an anoxic state, namely, air is not blown in, the carbonization treatment unit and the nitrification treatment unit are set to be in an aerobic state, namely, air is blown in, the denitration, reduction of easily biochemical COD and nitrification are sequentially realized, and the mixed liquid of a nitrification section flows back to a denitrification section through internal reflux in the device so as to provide nitrate for the nitrification section. The denitrification and carbonization can also be realized by separately arranging the denitrification treatment unit and the carbonization treatment unit. The denitration and COD reduction treatment can be carried out for multiple times to achieve good denitration and COD reduction treatment effects as far as possible, the invention is not particularly limited as long as the denitration and COD reduction treatment is realized until the total nitrogen content is less than 10mg/L, COD and less than 60mg/L, for example, denitrification + carbonization + nitration treatment, nitrification + carbonization treatment and ozone oxidation + carbonization treatment can be sequentially carried out, wherein the denitrification + carbonization + nitration treatment and the nitrification + carbonization treatment can be realized by activated sludge treatment and/or biofilm treatment, and the ozone oxidation + carbonization treatment can be realized by the comprehensive treatment of the ozone oxidation treatment and the activated sludge treatment and/or biofilm treatment.
According to the method of the present invention, the first concentration treatment and/or the second concentration treatment and/or the wastewater pre-concentration treatment may be a thermal evaporation concentration treatment and/or a membrane separation concentration treatment. The thermal evaporation concentration process is an operation of boiling and vaporizing a solution containing a solute and removing steam, thereby increasing the concentration of the solute in the solution, and the used equipment is called an evaporator and can be divided into a tubular heating chamber and a non-tubular heating chamber according to the structure of the heating chamber, such as a horizontal tubular evaporator, a central circulation tube evaporator, an external circulation type evaporator and the like. The membrane separation and concentration treatment is a process for separating, purifying and concentrating different components of feed liquid by utilizing the selectivity of a membrane. According to the process of membrane separation, the membrane separation is divided into processes such as microfiltration, ultrafiltration, reverse osmosis, dialysis, electrodialysis and the like. For the purpose of concentration by separating fresh water from a concentrated solution, preferably, the present invention employs a reverse osmosis concentration treatment and/or an electrodialysis concentration treatment. The reverse osmosis concentration treatment overcomes osmotic pressure through manual pressurization, so that water permeates a reverse osmosis membrane to generate a reverse osmosis process, namely a process of pressing the water from a concentrated solution to a low-concentration solution. The electrodialysis concentration treatment is driven by an external direct current electric field, and by utilizing the selective permeability of an ion exchange membrane (namely cations can permeate a cation exchange membrane, and anions can permeate an anion exchange membrane), anions and cations respectively move to an anode and a cathode, so that the aims of desalting, concentrating, refining or purifying the solution and the like are fulfilled. The apparatus used for the reverse osmosis concentration treatment and/or the electrodialysis concentration treatment may be selected according to the requirements of salt rejection, water yield, recovery rate, etc. of industrial treatment, and the present invention is not particularly limited, and may be, for example, a reverse osmosis apparatus commercially available from FILTEC series of Dow chemical company, USA, or an electrodialysis apparatus commercially available from BDB series of North chemical Water treatment facilities.
The invention will now be further illustrated by the following examples, but is not limited thereto. The instruments and reagents used in this example are those commonly used in the art, unless otherwise indicated.
The process wastewater used in the examples was fresh water desalination wastewater (where reverse osmosis wastewater Q is 98t/h and ion exchange wastewater Q is 16t/h) and cycle cooling system discharge wastewater (Q465 t/h), and the process wastewater was coal gasification wastewater (Q is 300t/h), high concentration process wastewater (Q is 25t/h) and low concentration process wastewater (Q is 300t/h) produced in coal chemical production, and its properties are shown in table 1.
TABLE 1
Examples
The production wastewater and the production sewage are respectively treated and utilized according to the attached figure 1.
Production wastewater treatment and salt crystallization system: the waste water discharged from 465t/h of the circulating cooling system (the properties are shown in the table 1) is subjected to pre-concentration treatment in a reverse osmosis device (the Dow FILMTEC series in America), 325t/h of desalted fresh water and 140t/h of concentrated water are generated, and 325t/h of desalted fresh water is sent to the circulating cooling system.
140t/h of the concentrated water and 114t/h of fresh water desalination wastewater (containing reverse osmosis drainage 98t/h and ion exchange drainage 16t/h, properties are shown in Table 1) are mixed, and lime-soda agent softening treatment (Suspart clarifier of Beijing Woltel company) and ion exchange softening treatment are sequentially carried out, so that first softened water with the hardness of 0.04meq/L and ion exchange softening regeneration wastewater are obtained, and the 2.5t/h of the first softened water and the ion exchange softening regeneration wastewater are obtained. And sequentially carrying out two-stage reverse osmosis desalination treatment (two-stage reverse osmosis desalination device of the Dow FILTEC series) and thermal evaporation concentration treatment (thermal evaporation concentration device of GE company in America) on the first softened water to obtain first concentrated fresh water and first concentrated water with the total salt content of 242 g/L. In an evaporative crystallizer (Swenson forced external circulation type in America), the discharge amount of the first crystallization tail liquid is controlled to control the nitrate concentration in the crystallization mother liquid to be below the saturated concentration, and sodium chloride crystallization is carried out at 48 ℃ and sodium sulfate crystallization is carried out at 90 ℃ respectively to obtain first crystallization fresh water, 0.32t/h of first crystallization tail liquid, 426kg/h of product salt sodium chloride and 67kg/h of product salt sodium sulfate.
Fresh water produced by the production wastewater series is 570t/h in total, and is sent into a circulating cooling system; and the ion exchange softening regeneration wastewater and part of the first crystallization tail liquid are used as the feed of the production sewage treatment system.
Production sewage treatment and salt crystallization system: the coal gasification wastewater (property shown in the table 1) is firstly subjected to lime-soda agent pre-softening treatment, and then is mixed with low-concentration production wastewater (property shown in the table 1) and high-concentration production wastewater (property shown in the table 1), wherein the water amount is 625t/h in total. The inlet water is mixed with 2.5t/h ion exchange softening regeneration waste water, 0.32t/h crystallization tail liquid and the crystallization tail liquid refluxed by the system. And (3) sending the mixed sewage into a concrete pool adopting an activated sludge process to carry out denitrification, carbonization and nitrification and denitrification and carbonization (adopting an aeration biological filter process) to obtain effluent with the total nitrogen content of 8mg/L, COD of 60 mg/L. The mixed sewage is sequentially subjected to lime-soda agent softening treatment to obtain second softened water with the hardness of 1.42meq/L, and the second softened water is sequentially subjected to two-stage reverse osmosis desalination treatment (two-stage reverse osmosis desalination device of Dow, USA) and thermal evaporation concentration treatment (thermal evaporation concentration device of GE company, USA) to obtain second concentrated water and second concentrated fresh water with the total salt content of 236 g/L623 t/h. And feeding the second concentrated fresh water into a circulating cooling system, and carrying out second crystallization treatment (a crystallizer of Swenson company in America) on the second concentrated fresh water to generate 2.8t/h of second crystallized fresh water, 804kg/h of mixed salt and 0.31t/h of second crystallization tail liquid.
The second concentrated fresh water and the second crystallized fresh water are sent to a circulating cooling system for 656 t/h; and carrying out reflux treatment on the crystallization tail liquid seeds at 0.16t/h, and discharging and storing the rest 0.15t/h in a tail liquid storage pool.
The production wastewater treatment and salt crystallization system and the production sewage treatment and salt crystallization system jointly generate desalted fresh water 1195t/h, all the desalted fresh water is recycled as the make-up water of the circulating cooling system, the circulating cooling concentration ratio is controlled to be 5, the total make-up water amount is 3153t/h, and the make-up water fresh water 1958t/h is needed.
Compared with the prior art, the production amount of mixed salt is reduced from 1297kg/h to 804kg/h, the production amount is reduced by 38 percent, and 493kg/h of product salt can be produced; the outward discharge amount is 0.33t/h when the crystallization tail liquid is not refluxed, the outward discharge amount is reduced to 0.15t/h and is reduced by 55% by adopting the reflux treatment of the crystallization tail liquid; the produced reclaimed water is desalted and fresh water, can be completely recycled as make-up water of the circulating cooling system, and reduces the make-up water amount by 38 percent.
The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (14)
1. A method for treating and utilizing coal chemical industry sewage and wastewater comprises the following steps:
(1) carrying out first softening treatment on the production wastewater to obtain first softened water with the hardness not more than 0.04 meq/L;
(2) carrying out first concentration treatment on the first softened water obtained in the step (1) to obtain first concentrated fresh water and first concentrated water with the total salt content higher than 200g/L, and sending the first concentrated fresh water into a reclaimed water recycling system;
(3) carrying out first crystallization treatment on the first concentrated water obtained in the step (2) to obtain first crystallized fresh water, first crystallized tail liquid and product salt, and feeding the first crystallized fresh water into the reclaimed water recycling system; the conditions of the first crystallization treatment include: controlling the concentration of nitrate radicals in the crystallization mother liquor to be below a saturated concentration by controlling the discharge amount of the first crystallization tail liquor, and respectively carrying out crystallization and precipitation of sodium chloride at 40-50 ℃ and sodium sulfate at 85-95 ℃;
(4) mixing the production sewage with the first crystallization tail liquid, and then carrying out denitration and COD reduction treatment to obtain effluent with the total nitrogen content of less than 10mg/L, COD and less than 60 mg/L;
(5) performing second softening treatment on the effluent obtained in the step (4) to obtain second softened water with the hardness lower than 1.5 meq/L;
(6) performing second concentration treatment on the second softened water obtained in the step (5) to obtain second concentrated fresh water and second concentrated water with the total salt content higher than 200g/L, and feeding the second concentrated fresh water into the reclaimed water recycling system;
(7) carrying out second crystallization treatment on the second concentrated water obtained in the step (6) to obtain second crystallized fresh water, second crystallized tail liquid and miscellaneous salts, feeding the second crystallized fresh water into the reclaimed water recycling system, recycling at least one part of the second crystallized tail liquid as the feed for denitration and COD reduction treatment in the step (4), and feeding the rest second crystallized tail liquid into a tail liquid storage pool;
wherein the production wastewater is wastewater which is not polluted by industrial materials; the production sewage is sewage polluted by industrial materials.
2. The method of claim 1, wherein in step (1), the production wastewater comprises fresh water desalination wastewater and/or recirculating cooling system drain wastewater.
3. The method according to claim 2, wherein when the production wastewater comprises a hydronic system discharge wastewater, the hydronic system discharge wastewater is subjected to a wastewater pre-concentration treatment to obtain pre-concentrated fresh water and pre-concentrated water with a total salt content higher than 6 g/L; and (2) then, carrying out the treatment of the step (1) on the obtained pre-concentrated water, and sending the obtained pre-concentrated fresh water into the reclaimed water recycling system.
4. The method according to claim 1, wherein in step (1), the first softening treatment comprises: carrying out agent softening treatment on the production wastewater to obtain agent softening wastewater and chemical sludge; carrying out ion exchange softening treatment on the obtained medicament softening wastewater to obtain first softened water; and then, the obtained first softened water is subjected to the treatment of the step (2).
5. The method according to claim 4, wherein the agent used in the agent softening treatment is selected from Ca (OH)2、Na2CO3And NaOH.
6. The method according to claim 4, wherein the ion exchange softening treatment comprises performing regeneration of an ion exchange resin to obtain ion exchange regeneration wastewater, and using the obtained ion exchange regeneration wastewater as a feed for the denitration and COD reduction treatment of step (4).
7. The method according to claim 1, wherein in the step (4), the production wastewater comprises at least one of low concentration production wastewater and high concentration production wastewater, wherein the low concentration production wastewater is production wastewater with COD concentration lower than 600mg/L, and the high concentration production wastewater is production wastewater with COD concentration higher than 1800 mg/L.
8. The method of claim 1, wherein in step (4), the production wastewater comprises coal gasification wastewater.
9. The method of claim 8, wherein when the production wastewater comprises coal gasification wastewater, the coal gasification wastewater is pre-softened to obtain pre-softened water with hardness lower than 2.0 meq/L; and then, carrying out the treatment of the step (4) on the obtained pre-softened water.
10. The method according to claim 9, wherein the pre-softening and/or second softening treatment is a medicament softening treatment.
11. The method according to claim 10, wherein the agent used in the agent softening treatment is selected from Ca (OH)2、Na2CO3And NaOH.
12. A method according to claim 3, wherein the first and/or second concentration treatment and/or wastewater pre-concentration treatment is a thermal evaporation concentration treatment and/or a membrane separation concentration treatment.
13. The method of claim 12, wherein the membrane separation concentration treatment is a reverse osmosis concentration treatment and/or an electrodialysis concentration treatment.
14. The method according to claim 1, wherein in the step (4), the denitrification and COD reduction treatment is at least one selected from the group consisting of an activated sludge treatment, an ozone oxidation treatment and a biofilm treatment.
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| KR20140045053A (en) * | 2012-10-08 | 2014-04-16 | 박채원 | Salt manufacture method |
| CN104230124A (en) * | 2014-09-30 | 2014-12-24 | 深圳能源资源综合开发有限公司 | Coal chemical industry wastewater zero emission technology and special equipment thereof |
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| KR20140045053A (en) * | 2012-10-08 | 2014-04-16 | 박채원 | Salt manufacture method |
| CN104230124A (en) * | 2014-09-30 | 2014-12-24 | 深圳能源资源综合开发有限公司 | Coal chemical industry wastewater zero emission technology and special equipment thereof |
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