CN115340251A - Carbon-neutralized zero-emission industrial water treatment system and treatment method - Google Patents

Abstract

The invention provides a zero-emission industrial water treatment system and treatment method based on carbon neutralization. The treatment system includes a sequentially connected pretreatment unit, a membrane concentration unit, a secondary ion removal unit, and a nanofiltration salt separation unit. The filtered water outlet of the nanofiltration salt separation unit is connected to the sodium chloride crystallization unit, and the concentrated water outlet of the nanofiltration salt separation unit is connected to the sodium sulfate or calcium chloride separation unit. Adopting the technical scheme of the present invention can effectively solve the problems of high energy consumption and carbon emission, large consumption of chemicals and evaporation steam, high operating cost, and serious membrane pollution in the existing zero-emission system. The investment and operating costs are low, and the energy consumption, Small carbon emissions, suitable for my country's current economic, social, technological development level and needs.

Description

A carbon-neutral zero-emission industrial water treatment system and treatment method

technical field

The invention belongs to the technical field of water treatment, and in particular relates to a carbon-neutral zero-emission industrial water treatment system and a treatment method.

Background technique

The traditional zero-emission process is a process with high cost, high energy consumption and high carbon emissions. The traditional zero-emission process mainly includes a pretreatment section, a membrane concentration section, a nanofiltration separation section, a sodium chloride crystallization section, and a sodium sulfate crystallization section.

Pretreatment section (dual-alkali decalcification): the incoming water first enters the regulating pool, which plays a role in regulating the water quality and quantity, and then lifts it into the high-density sedimentation tank with a pump, by adding a large amount of sodium carbonate, lime, and sodium hydroxide. , PFS (polymeric ferric chloride), and coagulant (PAM) organically combine to effectively remove calcium and magnesium ions, SiO ₂ , suspended solids, colloids, etc. in reclaimed water. And so on, to remove part of the organic matter (COD), the produced water flows into the ultrafiltration membrane tank for further filtration and purification.

At present, the removal of hardness (calcium and magnesium ions) is mainly divided into chemical softening method and ion exchange method. The chemical softening method refers to adding appropriate agents to the water to react with calcium and magnesium ions to form insoluble precipitates CaCO ₃ and Mg(OH) ₂ . Commonly used agents include lime, soda ash, and NaOH. The lime softening method is used to treat water with high temporary hardness, low permanent hardness and high alkalinity, and cannot remove permanent hardness and negative hardness in water. In order to obtain better results and achieve the purpose of removing as much hardness in water as possible, the method of combining medicaments is generally used, such as lime-soda ash method, sodium hydroxide-soda ash method, etc. The ion exchange method refers to the method of using an ion exchanger (cation resin) to exchange the ions in the water with the diffusible ions in the ion exchanger, thereby softening the water. The advantages of the ion exchange method are: the effect is stable and accurate, the process is mature, and the hardness of the effluent can be reduced to 0. In practical engineering applications, when the hardness of the incoming water is low, the ion exchange method is generally used for treatment, and when the incoming water hardness is high, the chemical precipitation method is generally used. However, when the calcium ion content is high, the combination of high-density pool removal and resin softening and removal of hardness is used, and the cost of chemicals is relatively high. For sulfate radical removal technology, barium salt precipitation method can remove sulfate radical (barium sulfate precipitation) very well, but there is still a problem of high cost.

Membrane concentration section: The ultrafiltration membrane mainly intercepts colloid and suspended impurities in the water, and sends the produced water to the produced water pool through the suction pump. The two-stage weak acid bed uses resin to further remove calcium and magnesium ions in the water. The weak acid bed is set in the form of clever series and parallel use. The water produced from the weak acid cation bed enters the softening pool.

The water in the softened pool enters the subsequent medium-pressure reverse osmosis device GTR4, first enters the security filter, removes 5um particle impurities, and then enters the reverse osmosis membrane device for desalination through high-pressure pump pressure, the reverse osmosis produced water enters the reuse pool, and the concentrated water enters Thick water tank, medium pressure reverse osmosis device recovery rate 70%.

Nanofiltration separation section: medium-pressure reverse osmosis produced water enters the reuse pool, and concentrated water enters the nanofiltration device after ozone catalytic oxidation + activated carbon device to reduce COD. The nanofiltration device adopts two-stage nanofiltration to ensure the purity of sodium chloride on the nanofiltration product water side.

Sodium chloride crystallization section: The two-stage nanofiltration product water is then concentrated by high-pressure reverse osmosis, and part of the product water is recovered. After the concentrated solution (NaCl) is concentrated by the MVR device, it enters the sodium chloride evaporation crystallizer for crystallization.

Sodium sulfate crystallization section: the concentrated water (Na ₂ SO ₄ ) from the nanofiltration device is pre-concentrated by the MVR evaporator, and then enters the freeze crystallization device, and the precipitated sodium sulfate decahydrate is dehydrated by a centrifuge and then sent to a hot melt tank for melting , and then enter the nitric acid recrystallization device for recrystallization, after centrifugal drying, it is packaged as a by-product sodium sulfate.

The traditional process route is mature and stable, but there are processes such as hardness removal, STRO concentration, sodium chloride, sodium sulfate crystallization, etc., which consume a lot of chemicals, high energy consumption, large steam consumption, serious membrane pollution, low quality sodium chloride, and miscellaneous salts Hazardous waste and other issues.

Contents of the invention

In view of this, the present invention discloses a zero-emission industrial water treatment system based on carbon neutrality to solve one of the above technical problems.

To this end, the technical scheme adopted in the present invention is:

A zero-emission industrial water treatment system based on carbon neutrality, which includes a sequentially connected pretreatment unit, a membrane concentration unit, a secondary ion removal unit, and a nanofiltration and salt separation unit, and the filtered water of the nanofiltration and salt separation unit The outlet is connected to the sodium chloride crystallization unit, and the concentrated water outlet of the nanofiltration salt separation unit is connected to the sodium sulfate or calcium chloride separation unit.

This technical solution is mainly aimed at the problems of high energy consumption and carbon emission, chemical consumption, large evaporation steam consumption, high operating cost and serious membrane pollution of the existing zero-emission system, and proposes a low-cost, low chemical consumption, low carbon emission Zero-discharge process technology system for industrial water treatment.

According to different influent water quality, use the above-mentioned units to make corresponding adjustments and combinations to realize the resource utilization of salt and water in a cost-effective manner. It has good economic, environmental and social benefits, and has broad application prospects. It is expected to provide industrial water zero discharge systems. New crafting paths.

As a further improvement of the present invention, the pretreatment unit includes sequentially connected high-density pools, UV composite catalytic modules, biological activated carbon filter pools, denitrification filter pools, and UV sterilization pools; the high-density pools are provided with calcium chloride or milk of lime A dosing port, the UV composite catalytic pool is provided with a catalyst dosing port. The pretreatment unit is mainly responsible for ammonia nitrogen or nitrate removal, calcium magnesium silicon fluorine plasma removal, organic matter removal, microbial inactivation and other functions.

As a further improvement of the present invention, the membrane concentration unit includes an ultrafiltration tank and a reverse osmosis tank, a first two-stage resin treatment module is arranged between the ultrafiltration tank and the reverse osmosis tank, and the raw water is realized through the combination of ultrafiltration and reverse osmosis. of enrichment.

As a further improvement of the present invention, the secondary ion removal unit includes a nanofiltration A pool and a nanofiltration B pool connected in sequence, the inlet of the nanofiltration A pool is connected to the concentrated water outlet of the reverse osmosis pool, and the nanofiltration Pool A is provided with an antiscalant addition port, and the concentrated water outlet of the nanofiltration A pool is connected to the nanofiltration B pool; the concentrated water outlet of the nanofiltration A pool is also connected to the entrance of the induced crystallization sedimentation tank, and the induced crystallization The crystallization sedimentation tank is provided with a seed crystal chemical addition port, and the outlet of the induced crystallization sedimentation tank is connected with the outlet of the high-density tank. The seed crystal agent is calcium sulfate seed crystal and coagulant. Further, a circulating pipeline is provided between the nanofiltration pool A and the nanofiltration pool B.

With this technical scheme, the concentrated water effluent from the nanofiltration pool A enters the nanofiltration pool B to further remove secondary ions, the concentrated water flows back to the entrance of the nanofiltration pool A, and calcium sulfate seeds and calcium sulfate are added to the concentrated water of the nanofiltration pool A. Coagulant, to realize the precipitation of calcium sulfate, so as to remove the secondary ions in sulfate and calcium ions; after the concentrated water is induced to crystallize, the precipitated clear liquid is returned to the water inlet.

As a further improvement of the present invention, the nanofiltration salt separation unit includes nanofiltration C pool and nanofiltration D pool connected in sequence, the inlet of the nanofiltration C pool is connected with the filtered water outlet of the nanofiltration B pool, the The concentrated water outlet of nanofiltration pool D is connected to the filtered water outlet of nanofiltration pool B.

As a further improvement of the present invention, the sodium chloride crystallization unit includes a second two-stage resin treatment module, a second reverse osmosis tank, an ED treatment tank, a regulating tank and a solar crystallization field connected in sequence, and the second two-stage resin The inlet of the treatment module is connected with the filtered water outlet of the nanofiltration D tank, and the fresh water outlet of the ED treatment tank is connected with the inlet of the two-stage resin treatment module. Further, the second two-stage resin treatment module uses chelating resin to remove calcium and magnesium ions, and realizes the concentration of sodium chloride solution through the combination of reverse osmosis and ED. After the ED treatment pool, a regulating pool is set up, which can adjust the capacity to the output of high-salt solution for one year. After the regulating pool, a solar crystallization field is set up to realize the crystallization of sodium chloride through solar evaporation and obtain high-quality crystalline sodium chloride. Sodium chloride can meet the needs of the two alkali industries.

As a further improvement of the present invention, the sodium sulfate or calcium chloride separation unit includes a third two-stage resin treatment module, a second ED treatment tank, a second regulation tank, a solar or MVR concentration tank connected in sequence, and the third The inlet of the two-stage resin treatment module is connected to the concentrated water outlet of the nanofiltration C tank, wherein the fresh water outlet of the second ED treatment tank is connected to the inlet of the third two-stage resin treatment module through a reverse osmosis module, and the The concentrated water outlet of the second ED treatment tank is connected with the second regulating tank. This unit mainly removes impurities by resin, concentrates by ED or STRO, deeply concentrates by solar energy or MVR, and crystallizes and separates to obtain liquid calcium sulfide or sodium sulfate.

As a further improvement of the present invention, the zero-discharge industrial water treatment system based on carbon neutrality also includes a backwash liquid and sludge treatment unit, and the backwash liquid and sludge treatment unit includes a sequentially connected regulating mixing tank, High-density tank, sludge thickening tank and sludge dehydration tank, the inlet of the regulating mixing tank is connected with the first two-stage resin treatment module, the second two-stage resin treatment module, the third two-stage resin treatment module, the ultrafiltration tank, the reverse The backwashing filtrate outlets of the osmosis tank, the second reverse osmosis tank, the nanofiltration A pool, the nanofiltration B pool, the nanofiltration C pool and the nanofiltration D pool are connected, and the adjustment mixing pool is provided with a pH regulator inlet. The high-density pool is equipped with calcium chloride or lime milk agent inlet. This unit collects the backwash filtrate of each resin and filter by adjusting the mixing tank, then adjusts the pH, enters the high-density tank, and adds calcium chloride or lime milk to the high-density tank to precipitate silicon, fluorine, sulfate, etc., and the supernatant Backflow into the water. The sludge generated in this section and the sludge discharged from the regulating tanks and high-density tanks are concentrated and then dehydrated, and finally the sludge is disposed of or recycled.

As a further improvement of the present invention, the carbon-neutral zero-emission industrial water treatment system further includes a green energy supply unit that provides electric energy. Among them, the green energy supply unit supplies most of the electric energy to achieve basic energy self-sufficiency. Among them, the proportion of wind power and photovoltaic is reasonably allocated according to the local meteorological conditions. Generally, the ratio of wind power and photovoltaic is 1:0.5~1. At the same time, the sum of wind power and photovoltaic power is 2~4 times the actual power. supply.

The present invention also discloses a zero-discharge industrial water treatment method based on carbon neutrality, which uses the above-mentioned zero-discharge industrial water treatment system based on carbon neutrality to treat industrial water, including the following steps:

Step S1, the industrial water to be treated enters the pretreatment unit to remove calcium ions, magnesium ions, silicon ions, fluorine ions, and some COD, and removes organic matter, ammonia nitrogen and Nitrate nitrogen, through UV sterilization to achieve deep removal of residual microorganisms in the denitrification section;

Step S2, the water treated in step S1 enters the membrane concentration unit, further removes SS particles through ultrafiltration, removes fluoride ions, silicate or calcium and magnesium ions through two-stage resin filtration depth, and concentrates raw water through reverse osmosis, The produced water is reused, and the concentrated water enters the next step;

Step S3, the water treated in step S2 enters the secondary ion removal unit, and when the concentration of calcium ions in the water is higher than 100mg/L, and the molar concentration of sulfate is greater than the molar concentration of calcium ions, it passes through two-stage high-efficiency interception calcium ion nanofiltration Membrane, to concentrate calcium ions, and then throw in sulfate root crystals and flocculants to remove;

When the concentration of calcium ions in the water is higher than 100mg/L and the molar concentration of calcium ions is greater than the molar concentration of sulfate radicals, the sulfate radicals and calcium ions are concentrated through two-stage high-efficiency interception sulfate radical nanofiltration membranes, and then added with crystal seeds to remove them ;

When the concentration of calcium ions in the water is lower than 100mg/L, add sodium carbonate to remove calcium ions through the high-density pool;

Step S4, the water treated in step S3 enters the nanofiltration salt separation unit, and performs calcium chloride, sodium chloride or sodium sulfate, sodium chloride through the nanofiltration membrane with calcium ion, sodium ion or sulfate radical, and chloride ion separation function. separation of

Step S5, the filtered water treated in step S4 enters the sodium chloride crystallization unit, removes residual calcium and magnesium ions through a two-stage chelating resin, obtains regenerated water through reverse osmosis, concentrates sodium chloride through ED treatment, and then crystallizes through solar energy field to realize the crystallization of sodium chloride;

The concentrated water after the treatment in step S4 enters the sodium sulfate or calcium chloride separation unit, and according to the difference that the salt to be separated of the feed liquid is sodium sulfate or calcium chloride, the concentration of the feed liquid is selected through ED treatment or STRO treatment process; In the process of ED treatment, calcium ions are removed through two-stage chelating resin, and regenerated water is recovered through reverse osmosis C section; the concentrated solution of sodium sulfate or calcium chloride is further concentrated and separated through solar concentration field or MVR concentration module, and then The recovery of Glauber's salt is achieved through the temperature difference between night and day. During the concentration process, the MVR concentration module is used to separate the crude sodium chloride and obtain liquid calcium chloride according to the difference in solubility of calcium chloride and sodium chloride.

As a further improvement of the present invention, in step S1, pass the industrial water to be treated to adjust the pH to above 10 through a high-density pool and cooperate with a sand filter to remove calcium ions, magnesium ions, silicon ions, fluorine ions, and part of COD;

When the calcium and magnesium concentration of the industrial water to be treated is lower than 100mg/L, add sodium carbonate and sodium hydroxide to the high-density pool; when the calcium and magnesium concentration of the industrial water to be treated is higher than 100mg/L, add sodium Add pH adjuster to the pool to remove magnesium, active silicon and fluorine;

When the residual COD in the effluent of the high-density pool exceeds 10 mg/L, the organic matter is removed through the UV composite catalytic module and the biological activated carbon filter; when the residual characteristic organic matter in the incoming water is a polymer, the UV composite catalytic module adopts UV/ozone/hydrogen peroxide catalysis module, when the residual characteristic organic matter in the influent is a halogenated or nitro compound, the UV composite catalytic module adopts a UV/sulfite catalytic module; wherein, the ozone dosing quality is 1-3 times the COD removal quality, hydrogen peroxide and ozone The molar ratio of sodium sulfite to organic matter to be removed is 1:1~3, and the molar ratio of sodium sulfite to organic matter to be removed is 1:1~5; the bioactivated carbon adopts coal-based granular activated carbon, the iodine value is more than 950, and the residual ammonia nitrogen is less than 0.5;

The denitrification filter adopts ceramsite or pure sulfur carrier.

As a further improvement of the present invention, in step S2, if the calcium ion concentration of the industrial water to be treated is higher than 100mg/L, the two-stage resin adopts two-stage weak acid cation beds; if the calcium ion concentration of the industrial water to be treated is low When the concentration is 100 mg/L, the two-stage resin adopts a special resin for removing fluorine and silicon.

As a further improvement of the present invention, in step S3, if the concentration of calcium ions in the industrial water to be treated is higher than 100 mg/L, and the molar concentration of calcium ions is higher than the molar concentration of sulfate ions, the sulfate radical high-performance cut-off membrane is used for treatment , concentrated to 4 times the saturation concentration of calcium sulfate;

If the concentration of calcium ions in the industrial water to be treated is higher than 100mg/L, and the molar concentration of calcium ions is lower than the molar concentration of sulfate ions, the calcium ion high-performance interception membrane is used for treatment and concentrated to 4 times the saturated concentration of calcium sulfate;

If the calcium ion concentration in the raw water is lower than 100 mg/L, step S3 is omitted.

As a further improvement of the present invention, in step S4, a sodium sulfate cut-off membrane and a calcium ion cut-off membrane are used to separate calcium chloride, sodium chloride or sodium sulfate and sodium chloride.

Compared with prior art, the beneficial effect of the present invention is:

Adopting the technical scheme of the present invention can effectively solve the problems of high energy consumption and carbon emission, large consumption of chemicals and evaporation steam, high operating cost, and serious membrane pollution in the existing zero-emission system. Low cost, low energy consumption and low carbon emissions, suitable for my country's current economic, social and technological development level and needs; avoid the problem of low quality sodium chloride in the traditional zero discharge process; avoid the heat in the process of traditional concentrated water treatment and recycling High energy consumption and high carbon dioxide emissions of salt separation by traditional or cold methods; it can greatly reduce the generation and discharge of hazardous waste from miscellaneous salts; it avoids the high chemical consumption and high The problem of cost; avoiding the problem of high carbon emissions in the traditional zero-discharge process; also avoiding the inlet COD caused by the direct return of the sludge dewatering clear liquid in the traditional zero-discharge process, the problem of elevated hetero ions, and the membrane fouling of the traditional zero-discharge process Serious, frequent chemical cleaning and low membrane life.

Description of drawings

FIG. 1 is a schematic flow diagram of a zero-discharge industrial water treatment system based on carbon neutrality according to an embodiment of the present invention.

Fig. 2 is a process flow chart of an embodiment of the present invention when the calcium ion concentration is greater than 100 mg/L and the calcium ion molar concentration is higher than the sulfate radical concentration.

Fig. 3 is a process flow diagram of an embodiment of the present invention when the calcium ion concentration is greater than 100 mg/L and the calcium ion molar concentration is lower than the sulfate radical concentration.

Fig. 4 is a process flow diagram of an embodiment of the present invention when the calcium ion concentration is lower than 100 mg/L.

Detailed ways

The preferred embodiments of the present invention will be further described in detail below.

A zero-discharge industrial water treatment system based on carbon neutrality, illustrated by taking drained water as an example, as shown in Figure 1, the treatment system includes: ① pretreatment section, ② membrane concentration section, ③ secondary ion removal section , ④ nanofiltration salt separation section, ⑤ sodium chloride crystallization section, ⑥ sodium sulfate or calcium chloride separation section, ⑦ green energy supply section, ⑧ backwash liquid, sludge treatment section.

①The pretreatment section is equipped with high-density pool, UV composite catalysis, biological activated carbon, denitrification filter, UV sterilization and other units, respectively responsible for ammonia nitrogen or nitrate removal, calcium magnesium silicon fluorine plasma removal, organic matter removal, microbial inactivation and other functions . It is also possible to organically combine one or more of the above process units according to the quality of influent water.

Remove calcium, magnesium, silicon, fluorine plasma, part of COD and temporary hardness through high-density pool and sand filter, through UV catalyzed advanced oxidation or advanced reduction with biological activated carbon, denitrification filter to achieve deep removal of organic matter and ammonia nitrogen, nitrate nitrogen, through UV sterilization realizes the deep removal of residual microorganisms in the denitrification section, and then enters the ② membrane concentration section.

② In the membrane concentration section, two-stage resin is set between ultrafiltration and reverse osmosis to remove impurities, and the concentration of raw water is realized through the combination of ultrafiltration and reverse osmosis. Among them, SS particles are further removed by ultrafiltration, fluoride ions, silicate or calcium and magnesium ions are removed by two-stage resin, and raw water is concentrated by reverse osmosis. The recovery rate is controlled at 70%~75%. Concentrated water enters ③ the secondary ion removal section.

③ In the secondary ion removal section, sulfate or calcium ions are concentrated by nanofiltration, and scale inhibitors are added during the concentration process. The effluent of nanofiltration A concentrated water enters nanofiltration B to further remove secondary ions, the concentrated water flows back to the inlet section of nanofiltration A, and calcium sulfate seeds and coagulant are added to the concentrated water of nanofiltration A to realize calcium sulfate precipitation. Remove minor ions from sulfate and calcium ions. After the concentrated water is induced to crystallize, the precipitated clear liquid is returned to the water inlet.

The secondary ion removal section is mainly responsible for the concentration and supersaturation of ions with less concentration in sulfate or calcium ions, and then is removed through the destruction of the supersaturation process. As shown in Figures 2 to 4, when the concentration of calcium ions is higher than 100 mg/L and the molar concentration of sulfate radicals is greater than that of calcium ions, two-stage high-efficiency calcium ion nanofiltration membranes are used to achieve high concentration of calcium ions , and then cast sulfate root crystals and flocculants to remove. When the concentration of calcium ions is higher than 100mg/L and the molar concentration of calcium ions is greater than the molar concentration of sulfate radicals, the high-fold concentration of sulfate radicals and calcium ions is achieved mainly through two-stage high-efficiency interception sulfate radical nanofiltration membranes, and then seed crystals are added. remove. When the calcium ion concentration is lower than 100mg/L, the calcium ion is mainly removed by adding sodium carbonate to the high-density pool, and this paragraph is cancelled. In this section, the nanofiltration A concentrated water is induced to crystallize and precipitate, and then flows back to the front end of the sand filter, and the nanofiltration effluent enters the ④ nanofiltration salt separation section.

④ The nanofiltration salt separation section adopts two-stage nanofiltration to separate sodium chloride, sodium sulfate or sodium chloride and calcium chloride.

This section mainly achieves the separation of calcium chloride, sodium chloride or sodium sulfate, sodium chloride by setting up a nanofiltration membrane that efficiently separates calcium ions, sodium ions or sulfate radicals, and chloride ions. The filtered water enters the ⑤ sodium chloride crystallization section, and the concentrated water enters ⑥ the sodium sulfate or calcium chloride separation section.

⑤ The sodium chloride crystallization section is equipped with chelating resin to remove calcium and magnesium ions, and the concentration of sodium chloride solution is realized through the combination of reverse osmosis and ED. At the same time, a large-scale adjustment pool is set up in the ED concentrated water, and the adjustment capacity is the output of high-salt solution for one year. After the adjustment pool, a solar crystallization field is set up to realize the crystallization of sodium chloride through solar evaporation and obtain high-quality crystalline sodium chloride. Sodium chloride can meet the needs of the two alkali industries.

In this section, residual calcium and magnesium ions are removed through two-stage chelating resin, regenerated water is obtained through reverse osmosis, and sodium chloride is concentrated through ED to 190,000, and then sodium chloride is crystallized through a solar crystallization field to obtain high-quality product salt.

⑥The separation section of sodium sulfate or calcium chloride is equipped with different process combinations according to the different sodium sulfate or calcium chloride systems. Mainly through resin removal, ED or STRO concentration, deep concentration through solar energy or MVR, crystallization and separation, so as to obtain liquid calcium sulfide or sodium sulfate.

Further, according to the difference that the salt to be separated of the feed liquid is sodium sulfate or calcium chloride, the concentration of the feed liquid is realized through the ED or STRO process, and when the ED process is adopted, the calcium ion is removed by the two-stage chelating resin, and the reaction Permeate section C to realize reclaimed water recovery. The concentrated sodium sulfate or calcium chloride enters the solar energy concentration field or the MVR section for further concentration and separation, and then the sodium sulfate is recovered through the temperature difference between night and day to realize the recovery of thenardite, and the thenardite is further dissolved, crystallized, separated, and dried to produce high-quality sulfuric acid sodium. Through the different dissolution of calcium chloride and sodium chloride solution in the MVR concentration process, the separation of crude sodium chloride is realized and liquid calcium chloride is obtained.

⑦ The green energy supply section supplies most of the electric energy to achieve basic energy self-sufficiency. Among them, the proportion of wind power and photovoltaic is reasonably allocated according to the local meteorological conditions. Generally, the ratio of wind power and photovoltaic is 1:0.5~1. At the same time, the sum of wind power and photovoltaic power is 2~4 times the actual power. supply.

⑧ In the backwash liquid and sludge treatment section, each resin is collected by adjusting the mixing tank, the filtrate is backwashed through the filter tank, and then the pH is adjusted to enter the high-density tank. Calcium chloride or lime milk is added to the high-density tank to remove silicon, fluorine, Sulfate and other precipitates, and the supernatant is refluxed into water. The sludge generated in this section and the sludge discharged from the regulating tanks and high-density tanks are concentrated and then dehydrated, and finally the sludge is disposed of or recycled.

Specific treatment methods using the above systems include:

Preprocessing section:

(1) The drained water is first coagulated and precipitated under pH adjustment through the existing coagulation and sedimentation tank;

(2) Next, remove suspended solids and impurities through a sand filter system;

(3) Then use UV/ozone, biological activated carbon to remove organic matter, etc., to ensure the purity of crystal salt, and finally use ultraviolet light to sterilize.

Membrane concentration section:

(1) The pretreated desiccant water is adjusted by immersion ultrafiltration and double negative bed to remove silicon fluorine, COD, etc. under pH adjustment.

(2) Water desalination is achieved through reverse osmosis after adding antiscalant, the regenerated water is reused, and the concentrated water enters the concentration and separation unit for calcium sulfate removal.

Sulfate removal section:

(1) Concentrated water generated by nanofiltration induces crystallization and precipitation through seed crystal circulation to form calcium sulfate crystals; the supernatant is returned to the pretreatment unit.

Nanofiltration salt separation section:

(1) The concentrated water after membrane concentration is separated by two-stage nanofiltration (negative membrane) to separate solutions containing sodium chloride, calcium chloride or sodium sulfate, so as to facilitate subsequent resource utilization;

Calcium chloride or sodium sulfate separation section:

(1) When the influent water is calcium chloride, the filtered water passes through two-stage nanofiltration (negative membrane), and then the concentrated water after two-stage nanofiltration (positive membrane) enters the STRO membrane of the calcium chloride separation unit, Realize the desalination of nanofiltration water, industrial reuse of fresh water, and sale, and homogenization and equalization of concentrated water into the regulating tank;

(2) The TDS of concentrated water after adjustment is about 90,000, and 20%~40% liquid high-quality calcium chloride is produced through MVR multi-stage concentration for sale.

(3) When the influent is sodium sulfate, calcium and magnesium are deeply extracted through the chelating resin, and then deeply concentrated by ED with reverse osmosis, and then concentrated with the solar crystallization field, separated by day and night temperature difference to obtain Glauber's salt, redissolved with Glauber's salt, crystallized and separated, Dry to obtain Yuanming powder.

Sodium chloride crystallization unit:

(1) After two-stage nanofiltration (positive membrane) treatment, the filtered water passes through pressure ED + high-pressure reverse osmosis to realize the concentration of sodium chloride on the nanofiltration product water side, and realize the desalination of nanofiltration water, fresh water recycling, concentrated The water enters the large-scale regulating tank for homogenization and equalization;

(2) The concentrated water TDS of the high-efficiency solar crystallization field is adjusted to about 200,000, and then through the high-efficiency solar salt field, the local characteristics of large evaporation and low rainfall are used to realize high-efficiency solar crystallization, and high-quality crystalline salt is sold outside;

This technical solution mainly realizes the deep purification of organic matter and ammonia nitrogen (COD to 10mg/L, ammonia nitrogen to below 0.5mg/L) through the combination of ultraviolet catalytic advanced oxidation and advanced reduction process. Breaking through the traditional process of using the double-alkali method to remove calcium as the impurity removal method, the sulfate radical or calcium ion with a lower concentration is used as the main ion; through the antiscalant combined with nanofiltration supersaturated concentration and concentrated solution induced crystallization process to achieve sulfuric acid Economical and efficient removal of calcium, stable circulation and final removal of residual calcium sulfate through reflux; separation of sodium chloride, calcium chloride or sodium sulfate through calcium and sodium separation membranes or nanofiltration membranes for sulfate and chloride ion separation. Realize the economical and low-cost crystallization of sodium chloride through ED treatment and solar crystallization field; realize the separation of mirabilite through ED concentration and the difference in temperature difference between day and night in the solar crystallization field; obtain high-quality liquid chlorination through STRO reverse osmosis concentration and multi-stage MVR process Calcium: Through photovoltaic power generation and wind power generation, most of the power for the operation of the system is obtained, thereby realizing a carbon-neutral industrial water treatment zero-emission process system.

The technical solution of the present invention will be further elaborated and illustrated through specific examples below. It should be noted that the following specific embodiments are only for illustration, and the protection scope of the present invention is not limited thereto. In addition, the chemicals and raw materials used in the following examples are all commercially available or self-produced through known preparation methods.

Example 1

The water volume of mine water in a certain place in Northwest my country is 20,000 tons/day, the content of chloride ion is ~70,000 mg/L, the sulfate radical is 300-700 mg/L, the calcium ion is 1000 mg/L, the COD is 15 mg/L, the total nitrogen is 5 mg/L, and the total TDS 13,000mg/L. Using the traditional zero-emission process, after double-alkali method to remove calcium, then perform nanofiltration and salt separation, and then conduct sodium chloride, sodium sulfate thermal method, and cold method to separate salt. The daily consumption of sodium carbonate is as high as 53 tons, the cost of medicine per ton of water is 9.5 yuan, the total operating cost is 30 yuan per ton of water, and the annual operating cost is 230 million yuan. The total investment is 330 million yuan. The operating cost is too high, the energy consumption and carbon emissions are high, and the steam source is insufficient, so the project cannot be carried out, which affects production. After adopting the technical route of Fig. 3 of the present invention, inducing crystallization-calcium and sodium separation-solar crystallization-liquid calcium chloride utilization, the investment cost is basically unchanged, and the addition of sodium carbonate is completely avoided. The operating cost is reduced to 14.0 yuan/ton, and the annual operating cost is reduced to 100 million yuan/year. Through supporting solar energy and wind energy, a carbon-neutral industrial zero-emission system is realized. And produced 8 million tons/year of high-quality fresh water, 110,000 tons/year of high-quality sodium chloride and calcium chloride. The project has achieved considerable economic benefits, reduced the burden on enterprises, reduced environmental pollution, avoided a large amount of energy consumption and carbon emissions, effectively alleviated the local water shortage problem, and received good economic, social, and ecological environmental benefits. The effective reduction of operating costs and the protection of the local ecological environment have achieved good economic results. This model is being promoted in other similar fine chemical parks.

Example 2

A chemical company in Ningxia produces 15,000 tons of wastewater every day. After biochemical treatment, the COD is 150mg/L, the total TDS is 5000mg/L, the calcium ion concentration is 300mg/L, and the total nitrogen is 15mg/L. The total operating cost is 23 yuan/ton of water, and 20-30% of miscellaneous salts are produced, which must be disposed of as hazardous waste. The investment and operating costs are high, membrane pollution is serious, and the burden on enterprises is heavy. After adopting the technical route transformation in Figure 4 of the present invention, COD is removed to less than 10 mg/L before concentration, effectively controlling membrane fouling, total nitrogen is removed to less than 3 mg/L through the denitrification process, and calcium ions are removed through concentration-induced crystallization , retaining sodium sulfate. The miscellaneous salt rate is reduced to below 3%, the operating cost is reduced to 15 yuan/ton, and the annual operating cost is saved by 43 million yuan. Obtained considerable economic benefits, received good economic, social, ecological and environmental benefits.

Example 3

A pharmaceutical company in Shandong produces 10,000 tons of wastewater per day. After biochemical treatment, the COD is 200mg/L, the total TDS is 8000mg/L, the calcium ion concentration is 30mg/L, and the total nitrogen is 15mg/L. The cost is 20 yuan/ton of water, and 40% of miscellaneous salts are produced. The investment and operation costs are high, the membrane pollution is serious, and the burden on enterprises is heavy. After adopting the technical route design optimization of the present invention, COD is removed to less than 8mg/L before concentration, which effectively controls membrane fouling, reduces the rate of miscellaneous salts, and removes total nitrogen to less than 4mg/L through the denitrification process. The alkaline method removes a small amount of calcium ions and retains sodium sulfate. Salt separation through two-stage nanofiltration, salt separation through ED-solar crystallization field, deep agricultural economics through ED-reverse osmosis, sodium sulfate crystallization separation through day and night temperature difference, and secondary purification. Through the above process route design, the miscellaneous salt rate is reduced to less than 5%, the operating cost is reduced to 13 yuan/ton, and the annual operating cost is saved by 25 million yuan. Obtained considerable economic benefits, received good economic, social, ecological and environmental benefits.

The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be assumed that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deduction or replacement can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (10)

1. A zero-emission industrial water treatment system based on carbon neutrality, characterized in that: it includes a pretreatment unit, a membrane concentration unit, a secondary ion removal unit, and a nanofiltration salt separation unit connected in sequence, and the nanofiltration separation unit The filtered water outlet of the salt unit is connected to the sodium chloride crystallization unit, and the concentrated water outlet of the nanofiltration salt separation unit is connected to the sodium sulfate or calcium chloride separation unit. 2. The zero-discharge industrial water treatment system based on carbon neutrality according to claim 1, wherein the pretreatment unit includes a high-density pool, a UV composite catalytic module, a bioactive carbon filter, and a denitrification filter connected in sequence. pool, UV sterilizing pool; the high-density pool is provided with a calcium chloride or lime milk dosing port, and the UV composite catalytic pool is provided with a catalyst dosing port. 3. The zero-discharge industrial water treatment system based on carbon neutrality according to claim 2, characterized in that: the membrane concentration unit comprises an ultrafiltration tank and a reverse osmosis tank, and an ultrafiltration tank and a reverse osmosis tank are provided between the ultrafiltration tank and the reverse osmosis tank There is a first two-stage resin handling module. 4. The zero-discharge industrial water treatment system based on carbon neutrality according to claim 3, characterized in that: the secondary ion removal unit includes nanofiltration A pond and nanofiltration B pond connected in sequence, and the nanofiltration The inlet of the A pool is connected with the concentrated water outlet of the reverse osmosis pool, the nanofiltration A pool is provided with a scale inhibitor addition port, and the concentrated water outlet of the nanofiltration A pool is connected with the Nanofiltration B pool; The concentrated water outlet of the pool is also connected to the inlet of the induced crystallization sedimentation tank, the induced crystallization sedimentation tank is provided with a seed crystal agent addition port, and the outlet of the induced crystallization sedimentation tank is connected to the outlet of the high-density pool. 5. The zero-discharge industrial water treatment system based on carbon neutrality according to claim 4, characterized in that: the nanofiltration salt separation unit comprises sequentially connected nanofiltration C pond and nanofiltration D pond, and the nanofiltration The inlet of the C pool is connected with the filtered water outlet of the nanofiltration B pool, and the concentrated water outlet of the nanofiltration D pool is connected with the filtered water outlet of the nanofiltration B pool. 6. The zero-discharge industrial water treatment system based on carbon neutrality according to claim 5, characterized in that: the sodium chloride crystallization unit comprises a second two-stage resin treatment module, a second reverse osmosis tank, ED treatment pool, regulating pool and solar crystallization field, the inlet of the second two-stage resin treatment module is connected with the filtered water outlet of the nanofiltration D pool, the fresh water outlet of the ED treatment pool is connected with the entrance of the two-stage resin treatment module connect. 7. The zero-discharge industrial water treatment system based on carbon neutrality according to claim 6, characterized in that: the sodium sulfate or calcium chloride separation unit includes the third two-stage resin treatment module, the second ED, which are connected in sequence Treatment pool, second regulation pool, solar energy or MVR concentration pool, the inlet of the third two-stage resin treatment module is connected to the concentrated water outlet of the nanofiltration C pool, wherein the fresh water outlet of the second ED treatment pool The reverse osmosis module is connected to the inlet of the third two-stage resin treatment module, and the concentrated water outlet of the second ED treatment tank is connected to the second regulating tank. 8. The zero-discharge industrial water treatment system based on carbon neutrality according to claim 7, characterized in that: it also includes a backwash liquid and sludge treatment unit and a green energy supply unit, the green energy supply unit provides electric energy, The backwash liquid and sludge treatment unit includes a regulating mixing tank, a high-density tank, a sludge thickening tank and a sludge dewatering tank connected in sequence, and the inlet of the regulating mixing tank is connected to the first two-stage resin treatment module, the second two-stage The backwash filtrate of the three-stage resin treatment module, the third two-stage resin treatment module, the ultrafiltration pool, the reverse osmosis pool, the second reverse osmosis pool, the nanofiltration A pool, the nanofiltration B pool, the Nanofiltration C pool and the Nanofiltration D pool The outlet is connected, the adjustment mixing tank is provided with a pH regulator inlet, and the high-density tank is provided with a calcium chloride or lime emulsion agent inlet. 9. A zero-discharge industrial water treatment method based on carbon neutrality, characterized in that: it uses the zero-discharge industrial water treatment system based on carbon neutrality according to any one of claims 1 to 8 to treat industrial water , including the following steps: Step S1, the industrial water to be treated enters the pretreatment unit to remove calcium ions, magnesium ions, silicon ions, fluorine ions, and some COD, and removes organic matter, ammonia nitrogen and Nitrate nitrogen, through UV sterilization to achieve deep removal of residual microorganisms in the denitrification section; Step S2, the water treated in step S1 enters the membrane concentration unit, further removes SS particles through ultrafiltration, removes fluoride ions, silicate or calcium and magnesium ions through two-stage resin filtration depth, and concentrates raw water through reverse osmosis, The produced water is reused, and the concentrated water enters the next step; Step S3, the water treated in step S2 enters the secondary ion removal unit, and when the concentration of calcium ions in the water is higher than 100mg/L, and the molar concentration of sulfate is greater than the molar concentration of calcium ions, it passes through two-stage high-efficiency interception calcium ion nanofiltration Membrane, to concentrate calcium ions, and then throw in sulfate root crystals and flocculants to remove; When the concentration of calcium ions in the water is higher than 100mg/L and the molar concentration of calcium ions is greater than the molar concentration of sulfate radicals, the sulfate radicals and calcium ions are concentrated through two-stage high-efficiency interception sulfate radical nanofiltration membranes, and then added with crystal seeds to remove them ; When the concentration of calcium ions in the water is lower than 100mg/L, add sodium carbonate to remove calcium ions through the high-density pool; Step S4, the water treated in step S3 enters the nanofiltration salt separation unit, and performs calcium chloride, sodium chloride or sodium sulfate, sodium chloride through the nanofiltration membrane with calcium ion, sodium ion or sulfate radical, and chloride ion separation function. separation of Step S5, the filtered water treated in step S4 enters the sodium chloride crystallization unit, removes residual calcium and magnesium ions through a two-stage chelating resin, obtains regenerated water through reverse osmosis, concentrates sodium chloride through ED treatment, and then crystallizes through solar energy field to realize the crystallization of sodium chloride; The concentrated water after the treatment in step S4 enters the sodium sulfate or calcium chloride separation unit, and according to the difference that the salt to be separated of the feed liquid is sodium sulfate or calcium chloride, the concentration of the feed liquid is selected through ED treatment or STRO treatment process; In the process of ED treatment, calcium ions are removed through two-stage chelating resin, and regenerated water is recovered through reverse osmosis C section; the concentrated solution of sodium sulfate or calcium chloride is further concentrated and separated through solar concentration field or MVR concentration module, and then The recovery of Glauber's salt is achieved through the temperature difference between night and day. During the concentration process, the MVR concentration module is used to separate the crude sodium chloride and obtain liquid calcium chloride according to the difference in solubility of calcium chloride and sodium chloride. 10. The zero-discharge industrial water treatment method based on carbon neutrality according to claim 9, characterized in that: in step S1, the industrial water to be treated is adjusted to a pH above 10 through a high-density pool and a sand filter is used to remove Calcium ion, magnesium ion, silicon ion, fluoride ion, part of COD; When the calcium and magnesium concentration of the industrial water to be treated is lower than 100mg/L, add sodium carbonate and sodium hydroxide to the high-density pool; when the calcium and magnesium concentration of the industrial water to be treated is higher than 100mg/L, add sodium Add pH adjuster to the pool to remove magnesium, active silicon and fluorine; When the residual COD in the effluent of the high-density pool exceeds 10 mg/L, the organic matter is removed through the UV composite catalytic module and the biological activated carbon filter; when the residual characteristic organic matter in the incoming water is a polymer, the UV composite catalytic module adopts UV/ozone/hydrogen peroxide catalysis module, when the residual characteristic organic matter in the influent is a halogenated or nitro compound, the UV composite catalytic module adopts a UV/sulfite catalytic module; wherein, the ozone dosing quality is 1-3 times the COD removal quality, hydrogen peroxide and ozone The molar ratio of sodium sulfite to organic matter to be removed is 1:1~3, and the molar ratio of sodium sulfite to organic matter to be removed is 1:1~5; the bioactivated carbon adopts coal-based granular activated carbon, the iodine value is more than 950, and the residual ammonia nitrogen is less than 0.5; The denitrification filter adopts ceramsite or pure sulfur carrier; In step S2, if the calcium ion concentration of the industrial water to be treated is higher than 100 mg/L, the two-stage resin adopts two-stage weak acid cation beds; if the calcium ion concentration of the industrial water to be treated is lower than 100 mg/L, The two-stage resin adopts a special resin for removing fluorine and silicon; In step S3, if the concentration of calcium ions in the industrial water to be treated is higher than 100 mg/L, and the molar concentration of calcium ions is higher than the molar concentration of sulfate ions, the sulfate radical high-performance interception membrane is used for treatment, and concentrated to the saturation concentration of calcium sulfate 4 times; If the concentration of calcium ions in the industrial water to be treated is higher than 100mg/L, and the molar concentration of calcium ions is lower than the molar concentration of sulfate ions, the calcium ion high-performance interception membrane is used for treatment and concentrated to 4 times the saturated concentration of calcium sulfate; If the raw water calcium ion concentration is lower than 100mg/L, step S3 is omitted; In step S4, calcium chloride and sodium chloride or sodium sulfate and sodium chloride are separated by using a sodium sulfate cut-off membrane and a calcium ion cut-off membrane.

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