CN108483710B - Comprehensive seawater utilization method and system - Google Patents

Comprehensive seawater utilization method and system Download PDF

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CN108483710B
CN108483710B CN201810301118.6A CN201810301118A CN108483710B CN 108483710 B CN108483710 B CN 108483710B CN 201810301118 A CN201810301118 A CN 201810301118A CN 108483710 B CN108483710 B CN 108483710B
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seawater
tank
reverse osmosis
water
absorption tower
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CN108483710A (en
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张萍
许强
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Lianyungang Technical College
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    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00Multistage treatment of water, waste water or sewage
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/001Processes for the treatment of water whereby the filtration technique is of importance
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/20Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/44Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/441Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/52Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/08Seawater, e.g. for desalination
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2201/00Apparatus for treatment of water, waste water or sewage
    • C02F2201/002Construction details of the apparatus
    • C02F2201/007Modular design
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2301/00General aspects of water treatment
    • C02F2301/08Multistage treatments, e.g. repetition of the same process step under different conditions
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124Water desalination
    • Y02A20/131Reverse-osmosis

Abstract

The invention discloses a method and a system for comprehensively utilizing seawater, which are characterized in that struvite is generated by adding an inducer and a diluent together with calcium and magnesium plasma in seawater; removing the softened seawater with more than divalent cations in seawater, and treating by a sand filtration-security filtration-mixed matrix reverse osmosis combined membrane device to obtain fresh water; the separated softened strong brine basically removes calcium and magnesium particles, can replace industrial salt to enter the production of an alkali factory, simplifies the process flow of the traditional salt chemical industry, and greatly reduces the cost of salt chemical products such as sodium carbonate or caustic soda and the like. The invention is a new technology with environmental protection, energy saving and comprehensive utilization of seawater resources, and the energy consumption can be reduced and the fresh water production capacity can be improved by utilizing the technology to desalt the seawater.

Description

Comprehensive seawater utilization method and system
Technical Field
The invention relates to a seawater desalination technology, in particular to a method and a system for comprehensively utilizing seawater.
Background
The seawater desalination is one of the main methods for solving the crisis of fresh water, and is mainly divided into two main types, namely a distillation method (thermal method) and a reverse osmosis method (membrane method), and more than 20 specific seawater desalination technologies comprise multi-stage flash evaporation, low-temperature multi-effect, reverse osmosis, electrodialysis, vapor compression distillation, dew point evaporation, water and electricity cogeneration, hot membrane cogeneration, seawater desalination technologies utilizing nuclear energy, solar energy, wind energy and tidal energy and the like. Through the development of half a century, industrial technologies which take multistage flash evaporation, multi-effect distillation and reverse osmosis as main flows are formed.
Reverse Osmosis (RO) seawater desalination has been rapidly advanced in recent years, and the desalination installed capacity accounts for more than 65%. However, RO seawater desalination has the problems of high medicament and membrane cost, membrane surface scaling, large process energy consumption, high desalination cost, poor ecological effect of strong brine discharge and the like. In order to prevent the membrane from scaling, a nano-filtration-reverse osmosis combined seawater desalination process is adopted. For example, the nanofiltration-reverse osmosis (NF-RO) seawater desalination process proposed by Hassan A M, Al-Sofi M AK, Al-A moudi A and the like adopts the NF process to remove most of divalent ions and a part of monovalent ions in seawater, and then adopts the high-pressure RO process to further desalt to obtain the desalinated seawater. NF is adopted as the first stage desalination, the scale formation of the RO membrane surface can be effectively avoided, and the osmotic pressure of inlet water is reduced, thereby improving the recovery rate of water and the quality of produced water. However, the nanofiltration membrane also has the problem of membrane surface scaling; and the problem of strong brine after nanofiltration and reverse osmosis is still not solved; the energy-saving advantages of nanofiltration and reverse osmosis are not obvious enough, and the cost of desalinated water is still high. The research on RO seawater desalination at home and abroad mainly focuses on high-performance membranes and energy recovery devices, but the performance of polyamide membranes is nearly the limit, and the maturity of the energy recovery devices is high, so that the search for a new breakthrough point is the key for further improving the RO seawater desalination efficiency.
Disclosure of Invention
The invention aims to solve the technical problem of the prior art and provides a comprehensive seawater utilization method, which utilizes an inducer and a diluent to remove divalent ions in seawater to obtain struvite, desalts softened seawater, recycles strong brine generated in the desalinization process, and has the characteristics of no discharge, no pollution and good comprehensive utilization effect.
The invention also aims to provide a seawater comprehensive utilization system for realizing the method.
The technical problem to be solved by the invention is realized by the following technical scheme, and the invention provides a comprehensive seawater utilization method, which comprises the following steps: (1) sand filtering seawater, adding inducer phosphate and/or ammonium salt into sand filtered seawater, and adjusting Mg in mixed solution2+、NH4 +、PO4 3-To a molar ratio of 1: 0.9-1.2: 1.1-1.2, adding a combined alkali liquor diluent consisting of ammonia water and a sodium silicate aqueous solution, adjusting the pH value of the mixed solution to 7.5-8.0, stirring the mixed solution for reaction, and performing solid-liquid separation to obtain softened seawater and a first product, namely struvite; (2) carrying out air stripping absorption treatment on the softened seawater, absorbing ammonia gas dissolved in the softened seawater by using phosphoric acid, and recycling ammonium phosphate generated after absorption; (3) carrying out sand filtration, security filtration and reverse osmosis treatment on the softened seawater subjected to the stripping absorption treatment to obtain a second product fresh water, wherein the working pressure of the reverse osmosis is 4.0-5.0 MPa; (4) and recovering the strong brine obtained by reverse osmosis to be used as a third product, wherein the third product is used for replacing industrial salt to be used as a soda plant for producing soda or caustic soda chemical products.
As a further improvement of the invention, in the step (1), the inducer is one or more of ammonium dihydrogen phosphate, ammonium hydrogen carbonate and disodium hydrogen phosphate.
As a further improvement of the invention, the steps(1) Adding inducer phosphate and/or ammonium salt, and adjusting Mg in the mixed solution2+、NH4 +、PO4 3-To a molar ratio of 1: 0.9: 1.1.
as a further improvement of the invention, the combined alkali liquor diluent is added in the step (1), the pH value of the mixed solution is adjusted to 8.0, and the mixed solution is stirred for reaction and then subjected to solid-liquid separation to obtain softened seawater and a first product struvite.
As a further improvement of the invention, the combined alkali liquor diluent added in the step (1) consists of ammonia water, silica sol and sodium silicate aqueous solution with the mass concentration of 0.1-0.3%.
As a further improvement of the invention, the mass concentration of the ammonia water in the combined alkali liquor diluent is 1.5%, the mass concentration of the sodium silicate is 0.1%, and the mass concentration of the silica sol is 0.2%.
As a further improvement of the invention, the working pressure of the low-pressure reverse osmosis in the step (3) is 4.5 MPa.
The invention also provides a seawater comprehensive utilization system for realizing the method, which comprises a struvite generating device, a blow-off treatment device, a seawater desalination combined device and a strong brine collecting device.
The struvite generating device is used for reacting seawater with the inducer to obtain struvite, and comprises a first sand filter, a medicine adding tank, a reaction tank and a struvite collecting device.
The inlet tube and the former pond in first sand filter are connected, the outlet pipe and the back pond of straining in first sand filter are connected, add the medicinal cupping including inducer dosing tank and combination alkali lye diluent dosing tank, inducer dosing tank pass through the drug delivery pipe with the back pond of straining is connected, makes inducer and the sea water mixture after straining, combination alkali lye diluent dosing tank pass through the drug delivery pipe with the outlet pipe of back pond of straining is connected to the reaction tank behind the static mixer, makes combination alkali lye diluent and mixed solution misce bene take place the reaction, generates struvite.
The reaction tank is connected with a sedimentation tank, the upper end of the sedimentation tank is connected with a water storage tank, softened seawater supernatant obtained after reaction is stored, and the bottom end of the sedimentation tank is connected with a centrifugal machine; centrifuge passes through the conveying pipeline and is connected with guanite collection device, collects the guanite that the reaction produced, centrifuge passes through the raceway and is connected with the wastewater collection pond, the wastewater collection pond pass through the raceway with the former pond is connected, and the waste water cyclic utilization who obtains the centrifugation.
The stripping device removes gas dissolved in the supernatant after the reaction, and comprises: a stripping tower, an acid absorption tower and a post-treatment tank.
The bottom of the water storage tank is connected with the upper end of the stripping tower through a water delivery pipe by a pump, the bottom of the stripping tower is connected with an effluent collecting well through a water delivery pipe, the effluent collecting well is connected with the post-treatment tank, and softened seawater subjected to stripping treatment is collected.
Blow off the tower bottom and be connected with the air buffer tank through the circuit, blow off the tower top through circuit and acid absorption tower bottom entry linkage, the acid absorption tower top is connected with the air buffer tank after being connected through circuit and draught fan again, the bottom and the phosphoric acid storage tank of acid absorption tower one side are connected, the circuit of acid absorption tower offside bottom through the pump with the absorption tower top is connected, the waste water discharge port of acid absorption tower bottom through the raceway with waste water collecting tank connects, realizes cyclic utilization.
The seawater desalination combined device comprises: the second sand filter, the security filtration, the mixed matrix reverse osmosis combined membrane device and the fresh water collection device; the post-treatment tank is connected with the second sand filter, the cartridge filter and the reverse osmosis membrane module in series through water pipes, and the low-pressure side of the reverse osmosis membrane module is connected with the fresh water collecting device through a water pipe; the strong brine collection device is connected with the high-pressure side of the reverse osmosis membrane component through a strong brine transfer pipe.
As a further improvement of the invention, the reverse osmosis membrane module is a polyamide mixed matrix reverse osmosis membrane module filled with nano zeolite.
As a further improvement of the invention, the first sand filter, the second sand filter and the security filter are respectively connected with back washing.
Compared with the prior art, the invention has the following technical effects:
firstly, seawater is pretreated by adding an inducer and an ammonia water and sodium silicate aqueous solution combined alkali liquor diluent, so that cations with more than two valences in the seawater are removed, precipitate struvite is formed in the process, the ammonia water and sodium silicate aqueous solution combined alkali liquor diluent can be used for enhancing the crystallization precipitation of the struvite, and the content of silicon elements in the struvite is increased;
secondly, the pretreated softened seawater is treated by a reverse osmosis combined membrane device to obtain fresh water; because the pretreatment basically removes the cations with more than two valences in the seawater, the scaling and pollution are reduced, and the cost is saved;
thirdly, the strong brine separated by seawater desalination basically removes calcium and magnesium particles, can be recycled to replace industrial salt to enter an alkali factory for production, comprehensively utilizes seawater in the whole process, obtains various products, and has no emissions and no pollution.
Drawings
FIG. 1 is a schematic diagram of the system architecture of the present invention.
Detailed Description
The embodiments of the present invention will be further described with reference to the accompanying drawings so as to facilitate the further understanding of the present invention by those skilled in the art, and do not limit the right thereto.
Example 1
Collecting near-shore seawater in Hongyun harbor region, wherein Total Dissolved Solids (TDS) of seawater is 34700Mg/L, and Mg2+1080mg/L,Ca2 +395 mg/L,SO4 2-2120 mg/L. The method comprises the following specific steps: filtering seawater with sand, adding inducer ammonium dihydrogen phosphate and disodium hydrogen phosphate to obtain Mg in the mixed reaction solution2+:NH4 +:PO4 3-=1.0:0.9: 1.1. The pH value is adjusted to 8.0 by a combined alkali liquor diluent consisting of 1.5 mass percent of ammonia water, 0.1 mass percent of sodium silicate and 0.2 mass percent of silica sol, the reaction time is 50 minutes, and solid-liquid separation is carried out after the reaction is finished. Supernatant is softened seawater, and solid substance is struvite containing nitrogen 4.8%27.1 percent of phosphorus, 8.5 percent of magnesium, 2.06 percent of calcium, 0.12 percent of sulfur, 0.06 percent of potassium and the like. TDS is about 28500 mg/L. The removal rate of calcium and magnesium ions in the original seawater is 95.63 percent, wherein the removal rate of calcium ions is 91.44 percent, and the removal rate of magnesium ions is 97.17 percent. The supernatant water quality is shown in Table 1.
TABLE 1 Water quality composition comparison table
Ion(s) Ca2+ K+ Mg2+ Na+ SO4 2-
Raw seawater 395 265 1080 9072 2120
Treating water 33.8 200 30.6 8920 1930
And (3) passing the treated supernatant softened seawater through a stripping tower and an absorption tower to remove ammonia dissolved in the softened seawater, reacting the ammonia with phosphoric acid in an acid absorption tower to generate ammonium phosphate, and recycling the ammonia dissolved in the softened seawater through phosphoric acid.
The softened seawater after the stripping absorption treatment is desalted, the turbidity of the effluent after sand filtration and security filtration is less than 0.3NTU, the SDI is less than 3, the reverse osmosis operating pressure is 4.5MPa, the TDS is less than 800mg/L, and the recovery rate reaches 65%.
Recovering strong brine on the high-pressure side of the reverse osmosis membrane; the recovered concentrated brine does not contain calcium and magnesium ions, can be used for alkali chemical production, and has positive effects of reducing the production cost of the alkali chemical production and simplifying the process flow.
Example 2
Collecting near-shore seawater in Hongyun harbor region, wherein Total Dissolved Solids (TDS) of seawater is 34700Mg/L, and Mg2+1080mg/L,Ca2 +395 mg/L,SO4 2-2120 mg/L. The method comprises the following specific steps: filtering seawater with sand, adding inducer ammonium dihydrogen phosphate and disodium hydrogen phosphate to obtain Mg in the mixed reaction solution2+:NH4 +:PO4 3-=1.0:1.0: 1.1. The pH value is adjusted to 8.0 by a combined alkali liquor diluent consisting of 3 mass percent ammonia water, 0.1 mass percent sodium silicate and 0.3 mass percent silica sol, the reaction time is 50 minutes, and solid-liquid separation is carried out after the reaction is finished. The solid matter is struvite, which contains over thirty elements, such as nitrogen 4.9%, phosphorus pentoxide 27.2%, magnesium 8.5%, calcium 2.05%, sulfur 0.12%, potassium 0.05%, etc. TDS is about 28500 mg/L. The removal rate of calcium and magnesium ions in the original seawater is 95.58 percent, wherein the removal rate of calcium ions is 91.39 percent, and the removal rate of magnesium ions is 97.11 percent.
And (3) passing the treated softened seawater through a stripping tower and an absorption tower to remove ammonia dissolved in the softened seawater, reacting the ammonia with phosphoric acid in an acid absorption tower to generate ammonium phosphate, and recycling the ammonia dissolved in the softened seawater through the phosphoric acid.
And desalting the softened seawater subjected to the stripping absorption treatment, and performing reverse osmosis treatment after sand filtration and security filtration to obtain fresh water.
Recovering strong brine on the high-pressure side of the reverse osmosis membrane; the recovered concentrated brine does not contain calcium and magnesium ions, can be used for alkali chemical production, and has positive effects of reducing the production cost of the alkali chemical production and simplifying the process flow.
Example 3
Collecting near-shore seawater in Hongyun harbor region, wherein Total Dissolved Solids (TDS) of seawater is 34700Mg/L, and Mg2+1080mg/L,Ca2 +395 mg/L,SO4 2-2120 mg/L. The method comprises the following specific steps: filtering seawater with sand, adding inducer ammonium dihydrogen phosphate and disodium hydrogen phosphate to obtain Mg in the mixed reaction solution2+:NH4 +:PO4 3-=1.0:1.1: 1.1. The pH value is adjusted to 8.0 by a combined alkali liquor diluent consisting of 1% ammonia water, 0.3% sodium silicate and 0.1% silica sol, the reaction time is 50 minutes, and solid-liquid separation is carried out after the reaction is finished. The solid matter is struvite, which contains over thirty elements, such as nitrogen 5.0%, phosphorus pentoxide 27.1%, magnesium 8.5%, calcium 2.05%, sulfur 0.12%, potassium 0.05%, etc. TDS is about 28500 mg/L. The removal rate of calcium and magnesium ions in the original seawater is 95.57%, wherein the removal rate of calcium ions is 91.34%, and the removal rate of magnesium ions is 97.11%.
And (3) passing the treated softened seawater through a stripping tower and an absorption tower to remove ammonia dissolved in the softened seawater, reacting the ammonia with phosphoric acid in an acid absorption tower to generate ammonium phosphate, and recycling the ammonia dissolved in the softened seawater through the phosphoric acid.
And desalting the softened seawater subjected to the stripping absorption treatment, and performing reverse osmosis treatment after sand filtration and security filtration to obtain fresh water.
Recovering strong brine on the high-pressure side of the reverse osmosis membrane; the recovered concentrated brine does not contain calcium and magnesium ions, can be used for alkali chemical production, and has positive effects of reducing the production cost of the alkali chemical production and simplifying the process flow.
Example 4
Connecting pipeNear-shore seawater in Harbour of cloud, Total Dissolved Solids (TDS) of seawater 34700Mg/L, wherein Mg2+1080mg/L,Ca2 +395 mg/L,SO4 2-2120 mg/L. The method comprises the following specific steps: filtering seawater with sand, adding inducer ammonium dihydrogen phosphate and disodium hydrogen phosphate to obtain Mg in the mixed reaction solution2+:NH4 +:PO4 3-=1.0:1.2: 1.1. The pH value is adjusted to 8.0 by a combined alkali liquor diluent consisting of 2% ammonia water, 0.2% sodium silicate and 0.2% silica sol, the reaction time is 50 minutes, and solid-liquid separation is carried out after the reaction is finished. The solid matter is struvite, which contains over thirty elements, such as nitrogen 5.1%, phosphorus pentoxide 27.1%, magnesium 8.5%, calcium 2.06%, sulfur 0.12%, potassium 0.05%, etc. TDS is about 28500 mg/L. The removal rate of calcium and magnesium ions in the original seawater is 95.57 percent, wherein the removal rate of calcium ions is 91.31 percent, and the removal rate of magnesium ions is 97.13 percent.
And (3) passing the treated softened seawater through a stripping tower and an absorption tower to remove ammonia dissolved in the softened seawater, reacting the ammonia with phosphoric acid in an acid absorption tower to generate ammonium phosphate, and recycling the ammonia dissolved in the softened seawater through the phosphoric acid.
And desalting the softened seawater subjected to the stripping absorption treatment, and performing reverse osmosis treatment after sand filtration and security filtration to obtain fresh water.
Recovering strong brine on the high-pressure side of the reverse osmosis membrane; the recovered concentrated brine does not contain calcium and magnesium ions, can be used for alkali chemical production, and has positive effects of reducing the production cost of the alkali chemical production and simplifying the process flow.
Referring to fig. 1, the seawater comprehensive utilization system for implementing the seawater comprehensive utilization method described in embodiments 1 to 4 includes a struvite generating device, a stripping treatment device, a seawater desalination combination device, and a concentrated brine collecting device. The system comprises a struvite generating device, a blow-off treatment device, a seawater desalination combined device and a strong brine collecting device; the struvite generating device is used for reacting seawater with the inducer to obtain struvite, and comprises a first sand filter 2, a medicine adding tank 3, a reaction tank 6 and a struvite collecting device 8; the water inlet pipe of the first sand filter 2 is connected with the raw water tank 1, the water outlet pipe of the first sand filter 2 is connected with the filtered water tank 4, the chemical feeding tank 3 comprises an inducer chemical feeding tank and a combined alkali liquor diluent chemical feeding tank, the inducer chemical feeding tank is connected with the filtered water tank 4 through a chemical conveying pipe, so that the inducer is mixed with filtered seawater, the lower part of the filtered water tank 4 is connected with an air blower, so that the inducer is uniformly mixed with the filtered seawater, the combined alkali liquor diluent chemical feeding tank is connected to the reaction tank 6 through a chemical conveying pipe and the water outlet pipe of the filtered water tank 4 after passing through a static mixer 5, so that the combined alkali liquor diluent is uniformly mixed with the mixed solution, and reacts to generate struvite; reaction tank 6 is connected with sedimentation tank 7, sedimentation tank 7 upper portion is connected with tank 11, deposits the softened seawater supernatant that obtains in the storage sedimentation tank 7, sedimentation tank 7 bottom is connected with centrifuge 9, centrifuge 9 is connected with struvite collection device 8, centrifuge 9 bottoms and waste water collecting tank 10 are connected, waste water collecting tank 10 through the pump with former pond 1 is connected, recycles the waste water of collecting.
The stripping device removes gas dissolved in the supernatant after the reaction, and comprises: a stripping tower 14, an acid absorption tower 16 and a post-treatment tank 18;
the bottom of the water storage tank 11 is connected with the upper end of a stripping tower 14 through a water delivery pipe by a pump, the bottom of the stripping tower 14 is connected with an effluent collecting well 15 through a water delivery pipe, and the effluent collecting well 15 is connected with a post-treatment tank 18 and used for collecting softened seawater subjected to stripping treatment;
blow and take off 14 bottoms in the tower and be connected with air buffer tank 17 through the circuit, blow and take off 14 tops in the tower and be connected through circuit and 16 bottoms entry in the acid absorption tower, 16 tops in the acid absorption tower are connected with air buffer tank 17 after circuit and draught fan are connected again, and phosphoric acid storage tank 12 is connected with the bottom of 16 one sides in the acid absorption tower, 16 offside bottoms in the acid absorption tower the circuit through the pump with 16 tops in the absorption tower are connected, the waste water of 16 bottoms in the acid absorption tower get rid of the mouth through with waste water collecting tank 10 connects, realizes cyclic utilization.
The seawater desalination combined device comprises: a second sand filter 19, a cartridge filter 20, a reverse osmosis membrane module 21 and a fresh water collecting device 23; the post-treatment tank 18 is connected with the second sand filter 19, the cartridge filter 20 and the reverse osmosis membrane module 21 in series, and the low-pressure side of the reverse osmosis membrane module 21 is connected with a fresh water collecting device 23; the reverse osmosis membrane is a polyamide mixed matrix reverse osmosis membrane filled with nano zeolite; the first sand filter 2, the second sand filter 19 and the security filter 20 are respectively connected with the back wash 13.
The strong brine collection device is connected with the high-pressure side of the reverse osmosis membrane module 21 through a strong brine storage tank 22 through a strong brine transfer pipe, and collects the filtered strong brine.

Claims (1)

1. A method for comprehensively utilizing seawater is characterized by comprising the following steps: the method comprises the following steps:
taking near-shore seawater in Hongyun harbor region, wherein the total dissolved solid TDS of the seawater is 34700Mg/L, and Mg2+ 1080mg/L,Ca2+ 395 mg/L,SO4 2-2120 mg/L; the method comprises the following specific steps: filtering seawater with sand, adding inducer ammonium dihydrogen phosphate and disodium hydrogen phosphate to obtain Mg in the mixed reaction solution2+:NH4 +:PO4 3-=1.0:0.9: 1.1; a combined alkali liquor diluent consisting of 1.5 mass percent of ammonia water, 0.1 mass percent of sodium silicate and 0.2 mass percent of silica sol is used for regulating the pH value to be 8.0, the reaction time is 50 minutes, and solid-liquid separation is carried out after the reaction is finished;
the treated supernatant softened seawater passes through a stripping tower and an absorption tower to remove ammonia dissolved in the softened seawater, the ammonia reacts with phosphoric acid in an acid absorption tower to generate ammonium phosphate, and the ammonia dissolved in the softened seawater is recycled through phosphoric acid;
desalting the softened seawater after the stripping absorption treatment, and performing reverse osmosis treatment after sand filtration and security filtration to obtain effluent with turbidity less than 0.3NTU, SDI less than 3 and reverse osmosis operating pressure of 4.5 MPa;
recovering strong brine on the high-pressure side of the reverse osmosis membrane; the recovered concentrated brine does not contain calcium and magnesium ions and is used for alkali chemical production;
the seawater comprehensive utilization system for realizing the seawater comprehensive utilization method comprises the following steps: a struvite generating device, a blowing-off treatment device, a seawater desalination combined device and a strong brine collecting device; the struvite generating device is used for reacting seawater with the inducer to obtain struvite, and comprises a first sand filter, a medicine adding tank, a reaction tank and a struvite collecting device; the water inlet pipe of the first sand filter is connected with a raw water tank, the water outlet pipe of the first sand filter is connected with a post-filtration water tank, the chemical adding tank comprises an inducer chemical adding tank and a combined alkali liquor diluent chemical adding tank, the inducer chemical adding tank is connected with the post-filtration water tank through a chemical conveying pipe, so that an inducer is mixed with filtered seawater, the lower part of the post-filtration water tank is connected with an air blower, so that the inducer is uniformly mixed with the filtered seawater, the combined alkali liquor diluent chemical adding tank is connected to the reaction tank through a chemical conveying pipe and the water outlet pipe of the post-filtration water tank after passing through a static mixer, so that the combined alkali liquor diluent is uniformly mixed with the mixed solution, and the reaction is carried out to generate struvite; the reaction tank is connected with a sedimentation tank, the upper part of the sedimentation tank is connected with a water storage tank, softened seawater supernatant obtained by sedimentation in the sedimentation tank is stored, the bottom of the sedimentation tank is connected with a centrifugal machine, the centrifugal machine is connected with a struvite collecting device, the bottom of the centrifugal machine is connected with a wastewater collecting tank, the wastewater collecting tank is connected with the raw water tank through a pump, and collected wastewater is recycled; the stripping device removes gas dissolved in the supernatant after the reaction, and comprises: a stripping tower, an acid absorption tower and a post-treatment tank;
the bottom of the water storage tank is connected with the upper end of the stripping tower through a water delivery pipe by a pump, the bottom of the stripping tower is connected with an effluent collecting well through a water delivery pipe, the effluent collecting well is connected with the post-treatment tank, and softened seawater subjected to stripping treatment is collected;
the bottom of the stripping tower is connected with an air buffer tank through a line, the top of the stripping tower is connected with an inlet at the bottom of the acid absorption tower through a line, the top of the acid absorption tower is connected with an induced draft fan through a line and then connected with the air buffer tank, a phosphoric acid storage tank is connected with the bottom end of one side of the acid absorption tower, the line at the bottom of the opposite side of the acid absorption tower is connected with the top end of the absorption tower through a pump, and a wastewater outlet at the bottom of the acid absorption tower is connected with the wastewater collection tank, so that cyclic utilization is realized;
the seawater desalination combined device comprises: the second sand filter, the cartridge filter, the reverse osmosis membrane module and the fresh water collecting device; the post-treatment tank is connected with the second sand filter tank, the security filter and the reverse osmosis membrane component in series, and the low-pressure side of the reverse osmosis membrane component is connected with a fresh water collecting device; the reverse osmosis membrane is a polyamide mixed matrix reverse osmosis membrane filled with nano zeolite; the first sand filter, the second sand filter and the security filter are respectively connected with back washing;
the strong brine collection device is connected with the high-pressure side of the reverse osmosis membrane module through a strong brine storage tank and a strong brine transfer pipe, and the strong brine after filtration is collected.
CN201810301118.6A 2018-04-04 2018-04-04 Comprehensive seawater utilization method and system Active CN108483710B (en)

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CN109368945A (en) * 2018-12-18 2019-02-22 江苏科技大学 Sewage from Ships processing and recovery of nitrogen and phosphorus integral system and method based on sea water magnesia source
CN110028215A (en) * 2019-04-26 2019-07-19 广东益诺欧环保股份有限公司 The purification device and application of synchronization process ammonium salt waste water and phosphate waste

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CN1413961A (en) * 2002-10-21 2003-04-30 广饶县盐化工业集团总公司 Method for preparing chemical fertilizer from salt-making mother liquor (bittern) or salt water
CN102001763A (en) * 2010-10-15 2011-04-06 天津欧纳海洋科技发展有限公司 Production method for desalting seawater by de-hardening preprocessing
CN102173526A (en) * 2011-03-08 2011-09-07 天津欧纳海洋科技发展有限公司 Method for using brine generated after seawater desalination as circulating cooling water for cooling tower of power plant

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Publication number Priority date Publication date Assignee Title
CN1413961A (en) * 2002-10-21 2003-04-30 广饶县盐化工业集团总公司 Method for preparing chemical fertilizer from salt-making mother liquor (bittern) or salt water
CN102001763A (en) * 2010-10-15 2011-04-06 天津欧纳海洋科技发展有限公司 Production method for desalting seawater by de-hardening preprocessing
CN102173526A (en) * 2011-03-08 2011-09-07 天津欧纳海洋科技发展有限公司 Method for using brine generated after seawater desalination as circulating cooling water for cooling tower of power plant

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