JP2570496C - - Google Patents

Description

Description: FIELD OF THE INVENTION The field of the invention is an apparatus for the washing and filtration of liquids, in particular water, which comprises at least one filtration membrane and contains water to be treated. This type has a circulating loop. [0002] The device according to the invention is preferably applied to the cleaning of water surfaces, but it is understood by those skilled in the art that other series of washing steps or waste or untreated water in the reprocessing of other liquids. It is also used for processing. [0003] The treatment of water for the purpose of distributing it for consumption has the following main objectives in view of the currently prevailing standard methods: -Removal of organics;-removal of harmful substances;-disinfection. A series of most standard treatments involves successive physicochemical steps of the type of coagulation-coagulation-decantation-filtration. . The filtration step of the new device presented by the present invention allows for improved processing and leaves almost no residual reagent. As is well known, in a "tangent filter", the liquid to be filtered is pressurized and circulates parallel to the filtration surface. On the other hand, in the case of a "surface filter", the liquid flows at right angles to the filtration surface. [0005] Tangent filters with inorganic membranes have more features than standard types of filters:-the chemical, thermal and bacteriological inertness of the inorganic membranes; Limitation of very fast clogging by self-cleaning of the filtration surface due to the transfer or transport of unfiltered fines at the tangent circulation rate of the water. [0006] Tangent ultrafiltration and microfiltration of inorganic membranes is considered an excellent method for water treatment, thereby reducing the size of the apparatus. These methods are usually performed in a circulation loop of the liquid to be treated, and some of the liquid (permeate) passes through the membrane when the filtrate is in the loop. Ultrafiltration is a process in which macromolecules, bacteria (diameter 0.
5 to 10 microns), a method of separating viruses and other microorganisms by asymmetric membranes whose pore size varies from 1 nanometer to 0.1 micron. For microfiltration, the pore diameter varies between 0.1 micron and 10 microns. [0007] One of the difficulties with tangent membranes is clogging, which takes various forms: surface clogging: when filtration is performed, there is a fixed boundary layer in the lysate in contact with the membrane. ,
From there, water flows out continuously, and the solutes contained therein are collected at irregularly high concentrations. This phenomenon is called concentration polarization, which forms a so-called polarization layer. The circulation rate of the fluid flowing tangent to the membrane is fast enough to promote self-cleaning of the membrane, and due to the formation of the polarizing layer and thus the rapid formation on the surface of this membrane, [0008] Internal clogging: the size of the colloid, which is especially in the microscopic material that can pass through the microfiltration membrane, is limited by the penetration and agglomeration of the membrane. Considerably larger than the pores, which promotes irreversible clogging;-chemical clogging: basically caused by hydrophobic substances such as proteins and oily microparticles. Based on the filtration action, the water can then be free of pathogenic microbial contamination by oxidizing agents (ozone, chlorine, etc.) or UV radiation, or the granular or powdered activated carbon does not fragment the treatment (trace amounts) Removal of pollutants, heavy metals such as trace elements, harmful smells and tastes). [0009] The use of ozone has applications in killing bacteria and viruses,
The steps of combining ozonation / coagulation, ozonation / flotation (flotation of ozone) or removal of taste and smell on the filtration medium, without mentioning other more standard applications such as ion extraction and manganese removal. Are also known to be effective. Finally, it is known that ozone has an oxidizing effect on trace contaminants (phenols, certain detergents, etc.) (see "New Development of Ozonization in B. Langlais"). Portable Water and Appropriate Technology (New Development of Ozonization in
Potable Water and Appropriate Technology) ''L'Eau,1'industrie, les nuisan
ces, 109, 1984, pp. 20-30). However, ozonation has two major limitations:-When oxidizing agents are used, it is common for chlorine to be chosen to serve as a disinfecting agent (with ozone radiation by UV radiation, Instead), while storing the treated water
Due to recontamination or residual effects that prevent possible recontamination during transfer to the distribution conduit. [0011] Furthermore, the use of gas is quite unsuitable in the filtration loop of a tanjet membrane. The gas is injected in the form of bubbles to maximize gas / liquid conversion.
It is presently known that clogging of the membrane is caused by foam expansion within the membrane. In January-February 1989, Liquides Magazine in September on liquid air dissolved in water by F.S. Duclert and M.C. “Microfiltration of Water Immineral Membraneness. Influence of Salt and Gases (Rumeau)
filtration of Water in Mineral Membranes.Influence of Salts and Gases) ”
As described in U.S. Pat. No. 5,867,898, the air released and dissolved by the atmosphere is promoted by the phenomenon of foaming by creating microbubbles of air in the pores. Upon coalescence, these bubbles then close the pores of the membrane. OBJECTS OF THE INVENTION It is an object of the present invention to provide a novel tangent membrane filtration device with ozone injection, despite the disadvantages and limitations known in the art. Another object of the present invention is to provide a liquid cleaning device, which can suppress surface clogging, internal clogging and chemical clogging of the membrane. It is a supplementary object of the invention to provide a device with several embodiments for injecting ozone, in particular, as a function of the properties of the liquid to be treated. [0013] These objects are achieved, as other objects will become apparent hereinafter, by a device for filtering and washing liquids such as water, which device comprises a filtration loop with a recirculation pump, And at least one tangent filtration membrane through which a portion of the liquid to be passed passes, further comprising an apparatus for adding an oxidizing gas to the liquid to be treated in a loop upstream of the membrane, the membrane comprising: To produce turbulence with the microbubbles of the gas sized to produce turbulence in the liquid at the point, combined with the oxidation phenomenon, which suppresses the clogging of the membrane, the outflow velocity and Physical of filtration /
It is to improve the chemical properties. According to the present invention, unlike the prior art, continuous fine bubbles have an effect of removing clogging because the boundary layer is reduced by turbulence generated by the movement of the bubbles. is there. This practical effect is related to the chemical oxidizing effect of the gas (particularly when the oxidizing gas is ionized), and the unexpected expansion of the gas within the film will break the risk of clogging. Can be. The size of the microbubbles is preferably from 10 μm to 2 mm in diameter, the proportion and concentration of gas added to the liquid to be treated varies as a function of the properties of the liquid to be treated, and the oxidizing gas is ionized. It is the air that was made. Preferably, the liquid to be treated undergoes a chemical pretreatment upstream of the filtration loop. Preferably, the filtration loop has an exhaust pipe to protect the recirculation pump against the microbubbles. In one particular embodiment, to treat water filled with organic substances, a predetermined amount of chemical reagents and adsorbent are provided downstream of an apparatus for injecting an ozonized gas, such as ozonized air. A device for injecting both or both is in the filtration loop. Preferably, the adsorbent is activated carbon. Therefore, according to the present invention, the ozonation process and the chemical treatment with the activated carbon can be simultaneously performed by using the tangent filtration membrane, and the cooperation which is extremely effective in increasing the efficiency of the filtration process is clearly formed. In another particular embodiment, the circulation loop includes a device for injecting oxidizing gas into the filtration loop. Said injection devices for oxidizing gas belong to the group comprising an emulsifier mounted upstream of the exhaust gas pipe, a porous material placed in the exhaust gas pipe, an ozonation-floating device and an ozone container. In the case of an ozonation-floating device, the ozonization-floating is performed by a porous material,
The sweep is performed by a recirculation conduit. According to another embodiment, the ozone is introduced by an emulsifier. In certain processes, the exhaust pipe is formed by a biological filter that is exposed to air, particularly when water is heavily filled with ammonia.
Preferably, the biomass support (biomass
The support is provided with the liquid injection device upstream thereof. As shown in FIG. 1, the filtration loop of the device according to the invention comprises, in a simple manner, a tangent membrane 1, an ozone microbubble injection device 2, an exhaust gas pipe 3, and a circulation pump 4. include. The liquid to be treated is led into the loop by a conduit 7 with a feed pump 5. The introduction of the liquid to be treated into the loop takes place at a point 6 between the exhaust pipe 3 and the recirculation pump 4. As already mentioned, advantageously, the introduction of ozone in the form of microbubbles increases the turbulence which reduces the boundary layer of the liquid circulating tangentially to the filtration membrane 1. This turbulence can prevent clogging of the membrane, which is related to the transfer of filter fines and the transfer of ozone and increased ionization reactions. In other words, the following interconnected effects can be seen:-a reduction in the water clogging force due to the reduced viscosity and a reduction in the thickness of the boundary layer according to the laws of liquid mechanics, where the outflow velocity of the permeation is reduced. Increases and reduces fogging on the membrane surface;-attacks and reduces organic matter contained in the water to be treated;-bactericidal, especially antibacterial, effects of ozone;-reduces the taste of the water; Increase in membrane life due to reduction. The oxidizing gas used is preferably ozone, which has an oxidizing and disinfecting action. This gas forms tasteful by-products and is preferred over chlorine, which has a deleterious effect on health. However, the invention is not limited to the use of ozone only. The determination of the amount of ozone injected in the form of microbubbles is dictated by the proportion and temperature of the quality of the treated water and the required level of quality of the treated water. This determination is made specifically to obtain a given level of oxidizing gas that is decomposed in the liquid being treated. For example, it is advantageous to obtain a fraction of cracked oxidizing gas on the order of 0 mg / 1 to 2 mg / 1, as measured by permeation at the output of the membrane. As described below, the choice of ozone can be explained by the ozone injection 2
This is because the second device can be provided in a filtration loop for the purpose of performing the ionization-floating process, especially under pressure. The tangent filtration membrane 1 used is advantageously an asymmetric type or a composite type inorganic membrane. As is well known, asymmetric membranes are typically made of polysulfate polymers and have holes in the shape of an overturned funnel. These features allow for less loss of load through the membrane as compared to symmetric membranes. In the case of composite membranes, layers of homogeneous micropores that decrease in size as the filtration surface approaches are overlapping. The diameter of the pores is determined by the first layer and is in contact with the liquid to be filtered. Thus, this type of membrane also appears to have the funnel turned upside down because the membrane encounters an increase in space, such as intersecting. At present, the use of organic membranes on the market is not appropriate in the presence of ozone. However, the membrane may be neutral to the oxidizing gas injected in the form of microbubbles, or a special oxidizing gas or mixture of oxidizing gases may be selected to be neutral to the material of the membrane. However, it cannot be excluded that the present invention can be applied to an organic membrane having tangent filtration. The ozone injection device 2 is configured by, for example, an emulsifier (also called a liquid jet vacuum pump or a hydro-injector). Furthermore, a Venturi type emulsifying device or any other type of device capable of producing microbubbles of oxidizing gas in a liquid may be used. The supply conduit 7 for the liquid to be treated preferably comprises a device for performing a chemical pretreatment of the liquid. It can be seen that the treatment of water and the injection of bubbles all have the effect of reducing the rate of clogging of the membrane 1. Therefore, the apparatus according to the invention significantly increases the duration of the filtration cycle of the membrane, especially because the period of the chemically unplugged period is delayed, so that a counter-flowing, unplugged beneficial process can be used. Is the case. In one particularly advantageous embodiment, the membrane is made unplugged by creating a circulation loop working in a closed circuit with clean water and continuing the injection of microbubbles of ozone. This process allows the membrane to be regenerated without any equipment changes or complications. In particular, a beneficial method of injecting the required soda and acid into special equipment can be performed and even replaced. Conveniently, during these periodic regeneration processes, a level of membrane output of residual ozone separated in the permeate can be obtained in the same order as the water treatment cycle. The process of regeneration by injecting ozone microbubbles may or may not be performed in concert with the reverse flow process. In the embodiment of FIG. 2, the device 10 for injecting the chemical reagent and / or the adsorbent is located downstream of the device 2 for injecting ozone microbubbles. These injection devices 10 are furthermore located upstream of the static mixer 11 and facilitate homogenization and the operation of the injection reagent. As a non-limiting example, an on-line static mixer can be used. The addition of reagents can increase the outflow rate of the filtration. The injection rate is the COD (Chemical Oxygen Demand) or T, which indicates the percentage of organic matter in the water being treated
It is determined as a function of OC (measurement of total organic carbon). Chemical reagents to be aggregated include, for example, alumina sulfide, polyaluminum chloride, and iron chloride. These non-depleting reagents have a flocculating effect which promotes the solidification of the microscopic substances contained in the water. When injecting an adsorbent, it is preferable to inject activated carbon. Activated carbon injected in powder form has a chemical effect on the filtration process. Activated carbon can further be replaced by briquettes in the form of macropores or pores, activated alumina, or even zeolites. The device of the present invention is provided with particularly valuable synergy by its combination with tangent filtration membranes, ozone microbubbles and activated carbon. FIG. 3 illustrates three possible modes of injecting ozone into two sets of injection points in the filtration loop. It is preferred to provide a second ozone injection point when treating water filled with organics or when iron extraction or manganese removal is required. In a first embodiment, the injection is carried out at point 12, for example by means of an emulsifier upstream of the exhaust gas pipe 3. In the embodiment of FIG. 4, the injection of the water to be treated takes place upstream of the circulation loop at point 14. The liquid thus treated is chemically treated before re-entering a new filtration cycle. Ozonization-floatation is a well-known technique, and refers to a technique in which ozone is injected into a liquid to form particles and cause an organic component of the liquid to float on the liquid surface. FIGS. 5, 6 and 7 show, for example, French Patent Application No. 8 dated June 18, 1986.
FIG. 3 illustrates three embodiments based on performing an ozonation-floating process with or without pressure, such as the type described in US Pat. In the case of the embodiment of FIG. 5, the ozonation is provided by the holes 15 and the sweep is performed by circulating in a loop. In the case of FIG. 6, ozone is introduced not through the hole 15 but by an emulsifier 16 for degassing and ozonation floating under pressure upstream of the exhaust gas pipe 3. Finally, the implementation of the ozonation-floating process takes place in the ozonation vessel 17 upstream of the filtration loop of FIG. FIG. 8 shows an embodiment of the filtration loop of the present invention, where a biological filter 20 exposed to air is placed. This filter 20 serves as an exhaust gas pipe and is also made of suspended material, and the water to be treated, to which reagents may be added, is injected upstream of the biomass support material. Microfiltration 2 with or without injection of ozonated air bubbles in the filtration loop
The following is a comparison of two examples. Example 1 Two treatments were carried out with the example of an average of 0.3 mg.1 of iron and 2 NTU of turbid water. Treatment by tangent ultrafiltration over the membrane (500 Angstrom holes). The circulation speed is 4.3 M / s, the transmembrane pressure is 1 bar and the clogging reverse flow is performed every 5 minutes for 5 seconds. 2. In the ozone treatment (1 g / m ³ ) performed by ultrafiltration on the membrane, the value of the treatment used is the same as in the first treatment, and the ozone is introduced into the recirculation loop upstream of the membrane by the emulsifier. Injected online. The outflow rates obtained with these two processes are given in Table 1. [Table 1] The ozonated air bubbles shown by this example do not interfere with the ultrafiltration properties:
The permeate flow is improved by about 30% by the ozone / tangent filtration combination. EXAMPLE 2 Seine water was subjected to two treatments: The flocculated Seine water was provided by tangent microfiltration over the membrane (0.2 μm holes). The speed of circulation was 4.4 m / sec and the transmembrane pressure was 1 bar; the reverse flow without clogging was performed for 5 seconds per 5 minutes. Dispersion purification was fixed at 301 / h. 2. The ozonation of the agglomerated Seine river water described above (rate 1 g / m ³ ) was carried out by ultrafiltration over a membrane; the operation values were the same as those of the first treatment. Ozone was injected into the online recirculation loop upstream of the membrane by an emulsifier. The results obtained from the two treatments are given in Table 2. [Table 2] This table is given untreated water (UW), the proportion of organic matter for the ratio (Abt) of the difference between the filtered water (FW) and these two measurements (mg of O ₂ per liter). Combining ozone with a coagulant can reduce organics by 75%. At the same operating conditions, the performance characteristics of the microfiltration are improved by the presence of ozonated air: the permeate flow is increased by 40%. This can be clearly seen in the test result graph of FIG. 9, which shows three curves of the following values obtained during another test. The last addition after the activated carbon has been introduced 92 in powdered form by the ozonated air microbubbles (91) which are continuous and then by the ozonized air bubbles (93) Changes in the effluent rate of filtration 90 with only condensed water circulating in loop (94) without agent; changes corresponding to the effluent of filtration (95); changes corresponding to the proportion of organic matter in the filtration. . Ozone was injected at a rate of 1 mg / 1. The amount of activated carbon added in 92 was 5 g. The test condition of the circulation speed in the loop was 4 m / s, and clogging in the reverse direction
Five seconds per minute, the load loss in the loop is 0.6 bar. From curve 90 it can be seen that the addition of ozonated air allows a filtration effluent rate which is almost twice as high as the circulation of flocculated water only (about 0.5 m ³ / h · m ² instead of about 0.5 m ³ / h · m ² ). Outflow velocity of 1 m ³ / h · m ² ). Furthermore, according to the second criterion, during the introduction of the powdered activated carbon into which the ozonized air has been injected into the liquid to be treated, the effluent in the filtration is lower than when only the ozonized air is injected. Note that the speed decreases. This can be explained by the fact that the addition of activated carbon increases the proportion of suspended matter in the water being treated. In contrast, it should be noted that in curve 96, the proportion of organic matter in the filtration is somewhat reduced in a correlated manner, which makes activated carbon / ozone synergistic properties, one of the preferred modes of practice of the invention, an advantage. Is shown. It should be understood that the invention is not limited by these embodiments. Thus, when the tangent membrane filtration loop is not being used to process a liquid, the method of the present invention is also performed to keep the loop during disinfection. This storage operation can be performed periodically and continuously.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing a first simplified embodiment of a filtration loop according to the present invention, wherein an injection device for ozone microbubbles is provided upstream of a tangent filtration membrane. FIG. 2 is an illustration showing a second embodiment of the filtration loop, showing an apparatus for injecting chemical reagents and / or adsorbents and a static mixing between the ozone injector and the tangent filtration membrane. Vessel is included. FIG. 3 shows the same one view for two embodiments of a second device for injecting ozone into the loop by means of an emulsifier or by means of a porous material respectively placed in the exhaust pipe of the filtration loop. FIG. FIG. 4 is an illustration showing a fifth embodiment of the loop according to the invention having a chemical state upstream of the circulation loop. FIG. 5 is an illustration showing a sixth embodiment of a loop including a fifth device for injecting ozone with a porous material based on an ionization-floating process under pressure. FIG. 6 is an explanatory view showing a seventh embodiment of the filtration loop according to the present invention, which has a second device for injecting ozone by an emulsifier performing an ozonization-floating process under pressure. . FIG. 7 is an illustration showing an eighth embodiment of a loop including a second device for injecting ions by an ionization tank performing an ozonation-floating process under pressure. FIG. 8 is an illustration showing a ninth embodiment of a filtration loop including a biological filter according to the present invention. FIG. 9 is an illustration showing actual results obtained by injecting ozone microbubbles into a loop for the treatment of Seine river water agglomerated by the method of the present invention. [Description of Signs] 1 Tangent membrane 2 Ozone microbubble injection device 3 Exhaust gas pipe 4 Recirculation pump 5 Supply pump 6 Point 7 Conduit 10 Device for injecting both or one of chemical reagent and adsorbent 11 Static mixer 12 Point 14 Point 15 hole 16 emulsifier 17 ozonation container 20 biological filter 90 filtration outflow speed 91 microbubbles of ozonized air 92 activated carbon introduction 94 coagulated water 95 filtration outflow speed 96 filtration outflow speed

Claims (1)

Claims: 1. An ozone gas source, a recirculation pump and a filtration loop having at least one tangent filtration membrane through which a part of the liquid to be treated flows out, said filtration membrane having a maximum size. Upstream of the flow of the liquid loop to be treated, having means for adding ozone as an oxidizing gas from the ozone gas source, said gas having a size of causing turbulence in the membrane liquid Microbubbles are formed, which, combined with the oxidation phenomenon, prevent clogging of the membrane, improve the physical / chemical properties and flow rate of the filtration, and allow chemical reagents and / or adsorbents to enter the filtration loop. Wherein the filtration loop is attached downstream of the membrane and has an exhaust pipe adapted to protect a recirculation pump against the microbubbles. Water treatment apparatus having a stringent filtration loop. 2. The device according to claim 1, wherein the diameter of the microbubbles is from 10 μm to 2 mm. 3. The method according to claim 1, wherein the proportion and concentration of the gas added to the liquid to be treated varies as a function of the properties of the liquid to be treated and / or the required proportion of separated residual gas. The described device. 4. The apparatus according to claim 1, wherein the liquid to be treated undergoes a chemical pretreatment upstream of the filtration loop. 5. The apparatus of claim 1 including a device for injecting a chemical reagent and / or an adsorbent into the filtration loop, wherein a static mixer is provided downstream of the device. 6. The apparatus according to claim 5, wherein said adsorbent is activated carbon. 7. The method according to claim 1, further comprising a second device for injecting an oxidizing gas into the filtration loop to perform treatment of water filled with organic matter, or extraction of iron or removal of magnesium. The described device. 8. A second apparatus for injecting an oxidizing gas into the loop includes an emulsifier mounted upstream of the exhaust gas pipe, a porous material in the exhaust gas pipe, an ozonation-floating device, and an ozonization apparatus. The device of claim 7, wherein the device belongs to a group that includes a container. 9. In a second apparatus for injecting an oxidizing gas into the loop, ozonation-floating is carried out under pressure, said ozonation being carried out by a porous material, the sweep being carried out by means of a recirculation conduit. 9. The device of claim 8, wherein said device is a device. 10. The apparatus according to claim 8, wherein the second apparatus for injecting an oxidizing gas is ozonized and floated under pressure, and the oxidizing gas is introduced by an emulsifier. 11. The apparatus according to claim 1, wherein said oxidizing gas is ozonized air. 12. The apparatus according to claim 8, wherein said exhaust pipe comprises a biological filter exposed to air when said liquid to be treated consists of water which is substantially filled with ammonia. 13. The apparatus according to claim 12, wherein the biological filter includes a suspended biomass support, and an injection device for the liquid to be treated is located upstream thereof. 14. The device for injecting microbubbles of the oxidizing gas is adapted to keep the tangent membrane filtration loop in a disinfecting environment while the loop is not being used to process a liquid. Item 14. Use of the device according to any one of Items 1 to 13. 15. The device for injecting microbubbles of the oxidizing gas regenerates the tangent filtration membrane during a regeneration cycle, wherein the regenerating action removes residual gas decomposed in the regenerated liquid. 2. The method according to claim 1, wherein the control is performed by an assigning device.
Use of the device according to any one of the preceding items 3.