CN114933379A - Short-flow reverse osmosis pretreatment system and method - Google Patents
Short-flow reverse osmosis pretreatment system and method Download PDFInfo
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- CN114933379A CN114933379A CN202210675956.6A CN202210675956A CN114933379A CN 114933379 A CN114933379 A CN 114933379A CN 202210675956 A CN202210675956 A CN 202210675956A CN 114933379 A CN114933379 A CN 114933379A
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- 238000001223 reverse osmosis Methods 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 32
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 221
- 238000000108 ultra-filtration Methods 0.000 claims abstract description 93
- 239000012528 membrane Substances 0.000 claims abstract description 63
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- 239000000126 substance Substances 0.000 claims abstract description 47
- 230000008025 crystallization Effects 0.000 claims abstract description 46
- 230000008569 process Effects 0.000 claims abstract description 22
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000011575 calcium Substances 0.000 claims abstract description 16
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 16
- 238000002203 pretreatment Methods 0.000 claims abstract description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 57
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 38
- 239000000919 ceramic Substances 0.000 claims description 38
- 238000003860 storage Methods 0.000 claims description 34
- CDBYLPFSWZWCQE-UHFFFAOYSA-L sodium carbonate Substances [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 24
- 238000000926 separation method Methods 0.000 claims description 21
- 239000007788 liquid Substances 0.000 claims description 20
- 238000011001 backwashing Methods 0.000 claims description 19
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 19
- 239000013078 crystal Substances 0.000 claims description 18
- 238000004519 manufacturing process Methods 0.000 claims description 17
- 239000002245 particle Substances 0.000 claims description 13
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- 239000003795 chemical substances by application Substances 0.000 claims description 8
- 238000006386 neutralization reaction Methods 0.000 claims description 6
- 229910010293 ceramic material Inorganic materials 0.000 claims description 3
- 229920000620 organic polymer Polymers 0.000 claims description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 abstract description 7
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- 239000000701 coagulant Substances 0.000 abstract description 5
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- 238000012423 maintenance Methods 0.000 abstract description 3
- 230000007774 longterm Effects 0.000 abstract description 2
- 230000002035 prolonged effect Effects 0.000 abstract description 2
- 238000001914 filtration Methods 0.000 description 15
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 10
- 239000011777 magnesium Substances 0.000 description 10
- 229910052749 magnesium Inorganic materials 0.000 description 10
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- 239000000047 product Substances 0.000 description 7
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- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 3
- 239000000347 magnesium hydroxide Substances 0.000 description 3
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 3
- 239000002351 wastewater Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 239000000084 colloidal system Substances 0.000 description 2
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- 238000004064 recycling Methods 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid group Chemical group S(O)(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
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- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 238000005352 clarification Methods 0.000 description 1
- 230000001112 coagulating effect Effects 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010612 desalination reaction Methods 0.000 description 1
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- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000008394 flocculating agent Substances 0.000 description 1
- 239000002223 garnet Substances 0.000 description 1
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- 239000010842 industrial wastewater Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F2001/5218—Crystallization
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/05—Conductivity or salinity
- C02F2209/055—Hardness
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/07—Alkalinity
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/14—Maintenance of water treatment installations
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/02—Softening water by precipitation of the hardness
-
- Y—GENERAL 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
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- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention discloses a short-process reverse osmosis pretreatment system and a short-process reverse osmosis pretreatment method, wherein high-hardness raw water is treated by a chemical crystallization circulating granulation fluidized bed and a polymeric porcelain ultrafiltration membrane device in sequence, the hardness of the water, particularly the hardness of carbonate or calcium, is effectively reduced, the outlet water SDI of the system is less than 3, the water inlet requirement of a reverse osmosis process is met, the long-term stable operation of reverse osmosis is facilitated, the chemical cleaning frequency of the reverse osmosis can be reduced, and the service life of a membrane is prolonged. The method has no coagulation process, does not need to add a coagulant, and eliminates the influence of the coagulant on a subsequent membrane system. The system has the advantages of short process flow, small occupied area of equipment, high automation degree, small operation and maintenance workload, high water yield of the system and long service life of the ultrafiltration membrane. The whole system is convenient to operate and manage, has small engineering quantity and has economic and environmental protection benefits.
Description
Technical Field
The invention belongs to the field of reverse osmosis pretreatment, and particularly relates to a short-flow reverse osmosis pretreatment system and method.
Background
With the improvement of environmental protection requirements, water sources used by industrial users tend to be diversified and have complicated water quality, for example, reclaimed water of urban sewage plants and coal mine drainage are adopted, and the industrial users also relate to the condition that a lot of production wastewater needs to be recycled, for example, the drainage of circulating cooling water and the like. While many industrial users require high quality desalinated water, with the development of water treatment technology, reverse osmosis processes are often first used in treatment systems for producing desalinated water. When using reverse osmosis processes, especially when high hardness water sources are encountered, a complete pretreatment is required to meet the water inlet standards for reverse osmosis.
Softening and clarifying, filtering and ultrafiltering are mostly adopted in the softening and clarifying process, the traditional softening and clarifying process adopts a treatment mode of adding lime/sodium hydroxide or jointly adding sodium carbonate into coagulating and clarifying equipment, filtering is carried out by adopting a medium, and finally, the filtered water enters a hollow fiber ultrafiltration membrane, so that the produced water reaches the reverse osmosis water inlet standard. In the softening process, a precipitator is added to generate calcium carbonate and magnesium hydroxide precipitate, and the calcium carbonate and the magnesium hydroxide precipitate and suspended matters are discharged in the form of sludge under the action of coagulation.
In the process, the traditional coagulation clarification equipment has low ascending flow velocity, the flow velocity is less than 10m/h, the treatment load is low, the treatment effect is easily influenced by water temperature and water quality, and the sludge amount is large; the flow rate of medium filtration is low, and backwashing is required at regular intervals, and backwashing equipment and backwashing wastewater collection and treatment equipment are required; the hollow fiber ultrafiltration membrane has poor pollution resistance, easy filament breakage and short service life. The whole system has complex composition, more accessory equipment and large sludge amount, and is easy to generate operation faults.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a short-flow reverse osmosis pretreatment system and a short-flow reverse osmosis pretreatment method, so as to solve the problems that the treatment load is low in the softening process, the treatment effect is easily influenced by water temperature and water quality, and backwashing equipment is required to be regularly used for backwashing during medium filtration in the conventional softening pretreatment process.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
a short-flow reverse osmosis pretreatment method comprises the following steps:
step 1, feeding raw water into a chemical crystallization circulating granulation fluidized bed, and adding an alkaline agent and seed crystals into the chemical crystallization circulating granulation fluidized bed to obtain calcium carbonate particles and softened water;
step 2, treating the softened produced water through a filter to obtain coarsely filtered produced water;
step 3, performing ultrafiltration on the coarsely filtered produced water through a poly-ceramic ultrafiltration membrane device to obtain ultrafiltered produced water; the water produced after ultrafiltration is used in a reverse osmosis system; the ultrafiltration membrane in the poly-ceramic ultrafiltration membrane device is made of an organic polymer ceramic material.
The invention is further improved in that:
preferably, in the step 1, when the alkalinity of the raw water is greater than or equal to the calcium hardness, sodium hydroxide is added into the chemical crystallization circulating granulation fluidized bed, otherwise, sodium hydroxide and sodium carbonate are added.
Preferably, in step 2, the softened produced water passes through the intermediate water storage device and then enters the filter from the intermediate water storage device.
Preferably, the softened produced water is subjected to acid neutralization treatment before entering the intermediate water storage device.
Preferably, in the step 4, the ultrafiltered produced water enters an ultrafiltration water producing tank, part of water in the water producing tank is shunted to a ceramic-gathered ultrafiltration membrane device, the ceramic-gathered ultrafiltration membrane device is backflushed and then enters a collecting tank, backflushing water flowing out of the collecting tank is separated by a solid-liquid separation fluidized bed, and separated clean water returns to an intermediate water storage device.
Preferably, in step 3, the produced water after ultrafiltration is subjected to acid neutralization treatment before entering a reverse osmosis system.
The short-flow reverse osmosis pretreatment system comprises a chemical crystallization circulating granulation fluidized bed, wherein the water outlet end of the chemical crystallization circulating granulation fluidized bed is connected with a filter, and the water outlet end of the filter is connected with a poly-ceramic ultrafiltration membrane device.
An intermediate water storage device is arranged between the chemical crystallization circulating granulation fluidized bed and the filter.
Preferably, the filter is a mesh filter or a laminated filter.
Preferably, the water outlet end of the ceramic-gathering ultrafiltration membrane device is connected with an ultrafiltration water production tank, an outlet of the ultrafiltration water production tank is provided with two branches, one branch is connected to the reverse osmosis system, the other branch is connected with the ceramic-gathering ultrafiltration membrane device, a back washing water outlet of the ceramic-gathering ultrafiltration membrane device is connected with a solid-liquid separation fluidized bed, and the outlet water of the solid-liquid separation fluidized bed is connected with a water inlet pipe of the intermediate water storage device.
Compared with the prior art, the invention has the following beneficial effects:
the invention discloses a short-process reverse osmosis pretreatment softening method, which comprises the step of sequentially treating high-hardness raw water by a chemical crystallization circulating granulation fluidized bed, a filter and a poly-ceramic ultrafiltration membrane device to obtain ultrafiltration product water. After the treatment by the process, the hardness of water, particularly the hardness of carbonate or calcium is effectively reduced, and meanwhile, the effluent SDI of the system is less than 3, so that the water inlet requirement of the reverse osmosis process is met, the process is favorable for the long-term stable operation of reverse osmosis, the chemical cleaning frequency of the reverse osmosis process can be reduced, and the service life of the membrane is prolonged. The process flow is simple, the equipment occupies a small area, the automation degree is high, the operation and maintenance workload is small, the water yield of the system is high, and the service life of the ultrafiltration membrane is long. The rising flow rate of the water fed into the chemical crystallization circulating granulation fluidized bed is high and can reach 60-120m/h, an alkaline medicament is added to react with the hardness of carbonate in raw water, the generated calcium carbonate is adsorbed on the surface of the crystal seeds which are put in advance, ions in the water realize chemical crystallization circulating granulation in the flowing process by utilizing an induced crystallization method, the generated calcium carbonate is discharged in a granular form, the purity of the calcium carbonate is high, the calcium carbonate can be recycled, and medium filtration or fiber filtration is not involved after crystallization granulation. The whole method has no coagulation process, does not need to add a coagulant, and eliminates the influence of a medicament on a subsequent system. The whole system is convenient for operation and management, has small engineering quantity and has economic and environmental protection benefits.
Furthermore, different alkaline agents are added according to different alkalinity and calcium hardness in raw water, so that the calcium removal effect is ensured.
Furthermore, the softened produced water is subjected to water quality adjustment through an intermediate water storage device, so that the uniformity and stability of subsequent treatment are ensured.
Furthermore, according to the requirements of different magnesium hardness in water, the softened produced water can be subjected to acid neutralization treatment before an intermediate water storage device or after ultrafiltration, and partial magnesium hydroxide precipitate generated in the chemical crystallization granulation process is removed, so that the treated water can meet the requirements on hardness.
Furthermore, the backwash water after ultrafiltration can be treated and recycled by using a solid-liquid separation fluidized bed, so that the whole system has a backwash water treatment and recovery function, the self-service water of the system is not lost, and the recovery rate is high.
The invention also discloses a short-flow reverse osmosis pretreatment softening system, which combines the chemical crystallization circulating granulation fluidized bed and the solid-liquid separation fluidized bed, so that raw water is subjected to treatment by the chemical crystallization circulating granulation fluidized bed, is subjected to coarse filtration by a filter, and is subjected to ultrafiltration by a ceramic-polymerized ultrafiltration membrane device. The chemical crystallization granulation fluidized bed mainly removes the hardness of calcium and magnesium, the filter precision is 10-3000 microns, and larger particle impurities such as silt, rust, microorganism, suspended matters, colloid and the like are removed; the filtering precision of the poly-ceramic ultrafiltration membrane device is 0.001-0.1 micron, particles, suspended matters, partial organic matters, colloid, oil, bacteria, most viruses and the like in water can be effectively removed, the effluent quality reaches SDI (standard deviation) less than or equal to 3, and the water inlet requirement of reverse osmosis is met. The system has the advantages of simple process flow, short flow, large water flux, high efficiency, high recovery rate, small equipment floor area, high automation degree, small operation and maintenance workload, good operation environment and high water yield of the system. The ceramic ultrafiltration membrane in the system is of a roll type, has no risk of broken filaments and has long service life.
Drawings
FIG. 1 is a process flow diagram of the present invention;
fig. 2 is a system configuration diagram of the present invention.
1-chemical crystallization circulating granulation fluidized bed; 2-an intermediate water storage device; 3-a first lift pump; 4-a filter; 5-a ceramic-gathering ultrafiltration membrane device; 6-ultrafiltration water production tank; 7-ultrafiltration backwashing water pump; 8-a collection tank; 9-a second lift pump; 10-solid-liquid separation fluidized bed.
Detailed Description
The invention is described in further detail below with reference to the following figures and specific examples:
example 1
Referring to fig. 1 and 2, the present embodiment provides a short-flow reverse osmosis pretreatment system comprising a chemical crystallization circulating granulation fluidized bed 1, a filter 4 and a poly-ceramic ultrafiltration membrane device 5.
The water outlet end of the chemical crystallization circulating granulation fluidized bed 1 is connected with the water inlet end of the filter 4, the water outlet end of the filter 4 is connected with the poly-ceramic ultrafiltration membrane device 5, and the water outlet end of the poly-ceramic ultrafiltration membrane device 5 is connected with the reverse osmosis system. The water inlet of the chemical crystallization circulating granulation fluidized bed 1 is high-hardness raw water, and the water inlet pressure is 0.2 MPa-0.4 MPa. An alkaline agent and seed crystals are added into the chemical crystallization circulating granulation fluidized bed 1, the alkaline agent reacts with the hardness of carbonate in raw water, the generated calcium carbonate is adsorbed on the surface of the seed crystals which are added in advance and is separated from the water in a particle form, specifically, calcium carbonate particles grow to 1-3 mm and then are discharged out of the bed body and are collected by a calcium carbonate collecting device, and the calcium carbonate is high in purity and can be recycled; preferably, the alkaline agent is sodium hydroxide or a mixture of the sodium hydroxide and the sodium carbonate, the calcium hardness removal capability of the sodium carbonate is stronger than that of the sodium hydroxide, when the alkalinity of raw water is greater than or equal to the calcium hardness, the sodium hydroxide is added into the chemical crystallization circulating granulation fluidized bed 1, otherwise, the sodium hydroxide and the sodium carbonate are added. The seed crystal added in the chemical crystallization circulating granulation fluidized bed 1 is domesticated garnet.
As one preferable scheme, an intermediate water storage device 2 is arranged between the chemical crystallization circulating granulation fluidized bed 1 and the filter 4, the intermediate water storage device 2 can uniformly buffer water flowing out of the chemical crystallization circulating granulation fluidized bed 1, and an acid agent can be added into a water inlet pipeline of the intermediate water storage device 2 according to requirements to perform acid neutralization treatment. An acid reagent can also be added at the outlet of the poly-ceramic ultrafiltration membrane device 5, the position of the added acid reagent is different depending on the difference of the requirements of magnesium hardness in the effluent, and if the magnesium hardness has strict requirements, the acid reagent is added at the outlet of the poly-ceramic ultrafiltration membrane device 5; if the hardness of the magnesium meets the general requirement, the magnesium can be added into the water inlet pipeline of the intermediate water storage device 2. Preferably, the acidic agent is sulfuric acid or hydrochloric acid.
Further, a first lift pump 3 is provided between the intermediate water storage 2 and the filter 4 for assisting the water in the intermediate water storage 2 to flow into the filter 4. The intermediate water outlet device 2 is an intermediate water tank or an intermediate water tank.
As one of the preferable schemes, the water outlet end of the polymer ceramic ultrafiltration membrane device 5 is connected with the ultrafiltration water production tank 6, the ultrafiltration water production tank 6 is used as a buffer device and is arranged at the water outlet end of the polymer ceramic ultrafiltration membrane device 5, and the water outlet of the ultrafiltration water production tank 6 of the polymer ceramic ultrafiltration membrane device 5 is connected with the reverse osmosis system.
As one of preferable embodiments, the filter 4 is a mesh filter or a laminated filter.
As one preferable scheme, the poly-ceramic ultrafiltration membrane device 5 is a conventional ultrafiltration membrane device, but the filtration membrane uses a roll-type organic polymer ceramic material, which is called poly-ceramic ultrafiltration membrane for short. The material has the characteristics of super-hydrophilic oleophobic surface, pollution resistance, high flux and easy cleaning; the filtration process of the poly-ceramic ultrafiltration membrane device 6 is to utilize the asymmetric micropore structure of the filtration membrane and the semipermeable membrane, and to make the solvent and the small molecular solute pass through the filtration membrane by taking the pressure difference between the two sides of the membrane as the driving force, so as to intercept the large molecular solute and obtain the clear water meeting the requirement of reverse osmosis water intake. The filter membrane is a roll-type structure, the flow channel of the roll-type ceramic ultrafiltration membrane gathering device 5 is wide, the flow capacity is large, the water quality fluctuation resistance range is large, the filtration precision is high, the effluent enters the ultrafiltration water production tank 6, and the normal SDI can be controlled within 3.
Example 2
Referring to fig. 1, the present embodiment provides a short-flow reverse osmosis pretreatment system, which includes a chemical crystallization circulating granulation fluidized bed 1, an intermediate water storage device 2, a filter 4, a ceramic ultrafiltration membrane device 5, and an ultrafiltration water production tank 6.
The water outlet end of the chemical crystallization circulating granulation fluidized bed 1 is connected with the water inlet end of the intermediate water storage device 2, the water outlet end of the intermediate water storage device 2 is connected with the filter 4, the water outlet end of the filter 4 is connected with the poly-ceramic ultrafiltration membrane device 5, the water outlet end of the poly-ceramic ultrafiltration membrane device 5 is connected with the ultrafiltration product water tank 6, the water outlet of the ultrafiltration product water tank 6 is provided with two branches, the first branch is connected with the second branch, the first branch is connected with the reverse osmosis system, the second branch is connected with the back-washing inlet of the poly-ceramic ultrafiltration membrane device 5, part of clear water flowing out of the ultrafiltration product water tank 6 carries out back-washing on the poly-ceramic ultrafiltration membrane device 5, the back-washing outlet of the poly-ceramic ultrafiltration membrane device 5 is connected with the collection pool 8, the water outlet of the collection pool 8 is connected with the solid-liquid separation granulation fluidized bed 10, and the water outlet of the solid-liquid separation fluidized bed 10 is communicated with the intermediate water storage device 2.
As one of the preferable schemes, an ultrafiltration backwashing water pump 7 is arranged on a branch of the ultrafiltration water production tank 6 connected to the polymer ceramic ultrafiltration membrane device 5, and a second lift pump 9 is arranged between the collection tank 8 and the solid-liquid separation granulation fluidized bed 10.
Example 3
The embodiment provides a reverse osmosis pretreatment method suitable for a high-hardness water source, which specifically comprises the following steps:
(1) raw water enters a chemical crystallization circulating granulation fluidized bed 1;
in the step, seed crystals are firstly added into a chemical crystallization circulating granulation fluidized bed 1; sodium hydroxide or a mixture of sodium hydroxide and sodium carbonate is added into a chemical crystallization circulating granulation fluidized bed 1, calcium in raw water reacts with the sodium hydroxide or the sodium carbonate in the chemical crystallization circulating granulation fluidized bed 1, the generated calcium carbonate precipitates are continuously attached to the surface of seed crystals in the bed, and the calcium carbonate precipitates grow to about 1-3 mm in particle size and are periodically discharged out of the chemical crystallization circulating granulation fluidized bed 1 from a particle discharge port. Specifically, when the alkalinity of water is insufficient and the calcium hardness is high, sodium hydroxide and sodium carbonate are added to remove calcium hardness.
(2) Softened produced water flowing out of the chemical crystallization circulating granulation fluidized bed 1 enters an intermediate water storage device 2 for regulation and buffering;
(3) the water of 2 in the water storage device passes through lift pump 3 in the centre, enters into the porcelain milipore filter device 5 after filter 4 carries out the coarse filtration, and the product water that flows out from the porcelain milipore filter device 5 gets into the water tank 6 is produced in the ultrafiltration, produces the water tank 6 in the ultrafiltration and cushions and even back, produces the water tank 6 from the ultrafiltration and flows into reverse osmosis system.
In the above steps, according to the water quality of the raw water and the requirements of subsequent systems, an acid adding operation can be performed, and the acid adding operation can be placed on the water inlet side of the intermediate water storage device 2 or on the water production outlet of the polymeric ceramic ultrafiltration membrane device 5. Specifically, when the magnesium hardness in the water is low and the subsequent system has no requirement on the magnesium hardness, the acid can be placed on the water inlet side of the intermediate water storage device 2; if the subsequent system requires hard magnesium removal, the acid adding point is arranged on the water outlet side of the poly-ceramic ultrafiltration membrane device 5 under the condition that the raw water has relatively low magnesium hardness, so that the removal rate of the total hardness is improved.
Example 4
The embodiment provides a reverse osmosis pretreatment method suitable for a high-hardness water source, which specifically comprises the following steps:
(1) raw water enters a chemical crystallization circulating granulation fluidized bed 1;
in the step, seed crystals are firstly added into a chemical crystallization circulating granulation fluidized bed 1; sodium hydroxide or a mixture of sodium hydroxide and sodium carbonate is added into a chemical crystallization circulating granulation fluidized bed 1, calcium in raw water reacts with the sodium hydroxide or the sodium carbonate in the chemical crystallization circulating granulation fluidized bed 1, the generated calcium carbonate precipitates are continuously attached to the surface of seed crystals in the bed, and the calcium carbonate precipitates grow to about 1-3 mm in particle size and are periodically discharged out of the chemical crystallization circulating granulation fluidized bed 1 from a particle discharge port. Specifically, when the alkalinity of water is insufficient and the calcium hardness is high, sodium hydroxide and sodium carbonate are added to remove calcium hardness.
(2) Softened produced water flowing out of the chemical crystallization circulating granulation fluidized bed 1 enters an intermediate water storage device 2;
(3) water from 2 in the middle water storage device passes through lift pump 3, enters into and gathers porcelain milipore filter device 5 after filter 4 filters, and the product water that flows out from gathering porcelain milipore filter device 5 gets into and produces the water tank, and the water that produces the water tank reposition of redundant personnel and does not exceed 10% product water volume gets into and gathers porcelain milipore filter device 5 and carry out the backwash, and the backwash drainage carries out recycle through setting up solid-liquid separation fluidized bed 10 alone and handles, improves the water yield of system. This portion of the backwash wastewater can also be uniformly treated by the industrial wastewater treatment system.
Specifically, no more than 10% of produced water flowing out of the ceramic ultrafiltration membrane device 5 enters an ultrafiltration water production tank 6 as an ultrafiltration backwashing water source; the ultrafiltration device regularly utilizes an ultrafiltration backwash water pump 7 to carry out backwash, backwash drainage enters a collecting tank 8, enters a solid-liquid separation fluidized bed 10 through a second lifting pump 9, is separated through the solid-liquid separation fluidized bed 10 and then enters an intermediate water storage device 2 for recycling treatment.
Whether or not the recovery treatment is carried out by the solid-liquid separation fluidized bed 10 may be determined according to the circumstances of the project. When solid-liquid separation and recovery treatment is set, a flocculating agent and a coagulant aid are required to be added, the water content of sludge generated by solid-liquid separation is high, and the sludge can be directly dewatered. The produced water directly enters ultrafiltration for reuse. As the backwashing water amount does not exceed the water yield of 10 percent, the coagulant aid added in the solid-liquid separation has no operation influence on a subsequent system.
The invention mainly aims at water sources with higher carbonate hardness or calcium hardness and lower turbidity (in principle within 100 NTU), and the reverse osmosis desalination treatment is adopted to remove the carbonate hardness so as to avoid scaling on the concentrated water side of the reverse osmosis membrane.
After raw water with certain pressure enters a chemical crystallization circulating granulation fluidized bed, NaOH is added through a medicine adding port (when the alkalinity in water is insufficient, Na is jointly added 2 CO 3 ) Fully reacting with the hardness of carbonate in raw water, attaching the generated calcium carbonate precipitate on the surface of the crystal seed in the fluidized bed to form calcium carbonate crystals, separating the crystals from the water in a separation zone, precipitating the crystal particles growing to a certain degree to the bottom, discharging the crystal particles out of the bed body, and recycling the generated calcium carbonate particles. The effluent enters an intermediate water storage device 2, enters a net type or laminated type filter through a lift pump, is filtered and then enters a poly-ceramic ultrafiltration membrane for filtration, and the water treated by the poly-ceramic ultrafiltration membrane enters an ultrafiltration water production tank 6.
The chemical crystallization circulating granulation fluidized bed is provided with a seed crystal feeding device, seed crystals are periodically supplemented into the bed body, and crystals growing to a certain degree are periodically discharged out of the body. And the ultrafiltration device carries out backwashing according to the pressure difference of inlet and outlet water, and backwashing water enters the collecting tank and is lifted to a solid-liquid separation water inlet through a pump for retreatment.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the scope of the present invention, which is intended to cover any modifications, equivalents, improvements, etc. within the spirit and scope of the present invention.
Claims (10)
1. A short-flow reverse osmosis pretreatment method is characterized by comprising the following steps:
step 1, raw water enters a chemical crystallization circulating granulation fluidized bed (1), and an alkaline agent and seed crystals are added into the chemical crystallization circulating granulation fluidized bed (1) to obtain calcium carbonate particles and softened water;
step 2, treating the softened produced water through a filter (4) to obtain coarsely filtered produced water;
step 3, performing ultrafiltration on the coarsely filtered produced water through a poly-ceramic ultrafiltration membrane device (5) to obtain ultrafiltered produced water; the water produced after ultrafiltration is used in a reverse osmosis system; the ultrafiltration membrane in the poly-ceramic ultrafiltration membrane device (5) is made of an organic polymer ceramic material.
2. The short-process reverse osmosis pretreatment method as claimed in claim 1, wherein in step 1, when the alkalinity of the raw water is equal to or higher than the calcium hardness, sodium hydroxide is added into the chemical crystallization circulating granulation fluidized bed (1), and otherwise, sodium hydroxide and sodium carbonate are added.
3. A short run reverse osmosis pretreatment process according to claim 1 wherein in step 2, softened product water passes through the intermediate water storage means (2) and from the intermediate water storage means (2) into the filter (4).
4. A short flow reverse osmosis pretreatment method according to claim 3, wherein the softened produced water is subjected to acid neutralization treatment before entering the intermediate water storage device (2); the middle water storage device (2) is a middle water pool or a middle water tank.
5. The short-flow reverse osmosis pretreatment method according to claim 3, wherein in the step 3, the produced water after ultrafiltration enters an ultrafiltration water production tank (6), part of the water is diverted from the ultrafiltration water production tank (6) to a poly-ceramic ultrafiltration membrane device (5), the poly-ceramic ultrafiltration membrane device (5) is subjected to back washing and then enters a collection tank (8), back washing water flowing out of the collection tank (8) is separated by a solid-liquid separation fluidized bed (10), and separated clean water returns to an intermediate water storage device (2).
6. The short-flow reverse osmosis pretreatment method of claim 1, wherein in step 3, the produced water after ultrafiltration is subjected to acid neutralization treatment before entering the reverse osmosis system.
7. The short-flow reverse osmosis pretreatment system is characterized by comprising a chemical crystallization circulating granulation fluidized bed (1), wherein a water outlet end of the chemical crystallization circulating granulation fluidized bed (1) is connected with a filter (4), and a water outlet end of the filter (4) is connected with a ceramic ultrafiltration membrane gathering device (5).
8. A short run reverse osmosis pretreatment system according to claim 7, wherein an intermediate water storage means (2) is provided between the chemical crystallization circulating granulation fluidized bed (1) and the filter (4).
9. A short stroke reverse osmosis pretreatment system according to claim 7, wherein the filter (4) is a screen filter or a disk filter.
10. The short-flow reverse osmosis pretreatment system according to claim 8, wherein the water outlet end of the poly-ceramic ultrafiltration membrane device (5) is connected with an ultrafiltration water production tank (6), the outlet of the ultrafiltration water production tank (6) is provided with two branches, one branch is connected to the reverse osmosis system, the other branch is connected with a backwashing water inlet of the poly-ceramic ultrafiltration membrane device (5), a backwashing water outlet of the poly-ceramic ultrafiltration membrane device (5) is connected with a solid-liquid separation fluidized bed (10), and the solid-liquid separation fluidized bed (10) is connected with a water inlet pipe of the intermediate water storage device (2).
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