JPS61257206A - Method of preventing growth of organism in reverse osmosis water purification system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to water purification, and more particularly, the present invention relates to reverse osmosis systems for water purification. Specifically, the present invention relates to methods and compositions for preventing biological growth on reverse osmosis membranes.

One of the most abundant natural resources on our planet
And, paradoxically, one of the most scarce natural resources is water. Approximately 75% of the Earth's surface is water, but since most of it is salt water or semi-saline water, only a small amount of water can actually be used by humans without treatment. Furthermore, since water, especially drinking water, is unevenly distributed across the globe, many inhabited areas are not blessed with abundant drinking water. Therefore, a need exists in many regions of the earth to purify brine or semi-brackish water to obtain potable water.

There are other human-created environments where there is a great need for an effective and relatively inexpensive means of purifying brine or semi-brine. For example, offshore wI drilling rigs are literally surrounded by water, but the water is completely undrinkable, and transporting water to such locations by tanker is extremely costly. One of the most effective means devised to provide fresh water in such environments is the reverse osmosis-water purification system.

The principle of reverse osmosis has been known for many years. In its simplest form, osmosis utilizes a membrane that is semipermeable to water and refuses the passage of dissolved salts. Under normal conditions, when pure water is separated from a salt solution by a semi-permeable membrane, water flows through the membrane from the pure water side to the non-pure water side, i.e. from the dilute solution side to the concentrated solution side; dilutes the concentrated solution and this continues until osmotic equilibrium is reached. The osmotic equilibrium is
This is achieved when the osmotic head becomes equal to the osmotic pressure of the salt solution. However, as is well known, when a sufficient amount of positive pressure is applied to the salt solution to overcome the osmotic pressure, the flow is reversed and water flows from the salt solution through the membrane to the pure water side of the membrane. Therefore, it is called reverse osmosis.

In a reverse osmosis-water purification system, non-pure water is pumped under high pressure into the system where it is contacted with a semipermeable membrane. The product water, which is 95-99% pure from dissolved minerals, emerges from the membrane and is discharged from the device. Since the output of a reverse osmosis purification system is highly dependent on the surface area of the membrane, there has been a number of efforts to develop improved systems that maximize pancreatic area while packaging the membrane in the least amount of space. A typical structure used in making a reverse osmosis water purification device is shown in FIG. FIG. 1 includes schematic parts and cross-sectional parts,
Please understand that this is a simplification. Structure αQ
comprises a membrane α2 supported on a cellular polymer matrix 0, said matrix (+4) being supported on a central foraminous support (t61). The screen αQ essentially acts as a spacer and provides some mechanical support.The spongy polymer matrix 04 provides some mechanical support and allows water to pass through the self-cutting blades.
Any suitable open cell 7 ohm material. Said membrane 0
2 can be any suitable material such as cellulose acetate,
A thin, somewhat brittle, semipermeable membrane made from cellulose triacetate, polyimide, or polysulfone. This structure is subjected to pressure, typically 600-800 ps.
When surrounded by salt water at i, the water passes through the membrane, moves through the polymer matrix, winds through the screen, and emerges from the outlet αe at one end of the structure. Essentially, the water flows along the path indicated by the arrow in FIG.

Said membrane does not allow dissolved mineral salts to pass through. The opposite side of exit α mark is blocked off.

As can be seen from the structure shown in FIG. 1, a structure large enough to provide commercial quantities of potable water would be extremely large and impractical. Therefore,
The structure used in the current device is rolled up like a jelly roll and inserted into a rigid casing.
A replaceable cartridge for the device is provided.

Water enters the cartridge from the inlet and flows through the helical coil, passing through the cartridge and the tube, passing through the membrane, and emerging from the central pipe of the helix.

Concentrated brine exits through the outlet.

It should be noted that the present invention is in no way related to reverse osmosis water purification equipment, and the above brief description of a typical equipment is as follows:
It should be understood that it is intended to illustrate the system we are interested in and the problem we are trying to solve.

Continuing the detailed description of the present invention, a typical water purification system based on reverse osmosis is shown in FIG. Non-pure water enters the pump (A) from the inlet. A chemical additive (the purpose of which will be described below) is injected into 5 inches of non-pure water at 124 and thoroughly mixed into the non-pure water by means of a mixing can. The water is passed through a filter to remove solid impurities and then passed through a booster pump to the cartridge filter 02 where small solid impurities are removed. Next, water is pumped into the reverse osmosis device c! using a pressure pump (b). Pump to 6J. The water that has passed through the reverse osmosis membrane in the cartridge is
device irc! Go out from exit a. Add disinfectant
The final product leaves the system at (4).

The condensation line exits the system from 04.

The continuous efficiency of a reverse osmosis system depends on the maintenance of the membrane to an unclogged condition. Perhaps the biggest problem encountered when using the Q system is membrane clogging by scale (or flakes). Typically, the membrane becomes clogged with scale deposits to the point that it must be replaced very frequently, in some cases as often as several times a month. In this case, it is necessary to remove the cartridge and replace it with a clean cartridge.

Treat the cartridges and pipes after use to remove scale.

It is clearly desirable to prevent scale build-up, or at least to increase the interval between cartridge and cartridge changes. It is common practice to inject non-pure water with some type of chemical additive used to prevent scale deposition.

In the prior art, "scale" generally meant calcium scale and magnesium scale.

Many additives are known for preventing scale deposition, which is the subject of all the drawbacks known in the prior art. The above-mentioned shortcomings are a result of our U.S. Pat. No. 4,58 entitled Scale Inhibitor for Reverse Osmosis Water Purification Systems.
This problem is solved by the scale inhibitor described in US Pat. No. 6,005. Please refer to the above-mentioned US patent specification for details.

For purposes of discussion herein, it is worth mentioning that the scale inhibitor compositions described in the aforementioned U.S. patents generally comprise a complementary combination of low molecular weight polyacrylic acid and phytic acid. That should be enough.

Regarding the problem of membrane clogging, the conventional technology solves another problem of reverse osmosis water purification systems, namely, the problem of microbial growth on the membrane;
I also recognized it. In particular, microorganisms attack cellulose membranes (which actually act as media). Prior art has tried chlorine as a biocide against these microorganisms. Although the scale inhibitor described in the patent specification has a remarkable effect on reducing the amount of scale, it was found that the polyacrylic acid in the inhibitor tends to support the growth of microorganisms.The polyimide film itself does not support microbial growth, but growth due to the presence of polyacrylic acid will cause clogging of polyimide membranes.Chlorine damages polyimide membranes and cannot be used as a biocide, and other commonly used Effective biocides such as There is an urgent need for biocides that are effective and safe against microorganisms.

Additionally, prior art scale inhibitors include one or more types of phosphates.

It is well known that phosphates support algae growth. Those skilled in the art usually do not have a particular interest in algae, since light is not considered to be a requirement of algae. The algae pass through the system along with the concentrated prine.

However, although algae in and of themselves are not particularly problematic, the inventors have found that they provide a situation that the inventors have found to be seriously problematic. to be specific,
In most of the systems mentioned above, and especially in those where polyacrylic acid is present, the algae provide an ideal environment for the growth of Bacillus subtilis species, which do not require light. Said Bacillus subtilis grows on polyacrylic acid. That is, the polyacrylic acid provides a medium for the Bacillus subtilis, and the Bacillus subtilis is also supplied to the algae. The gist of the above situation is that algae in itself is not considered to be the problem, but removal of the algae will remove important nutrients for blight, which is a significant problem, and therefore should be controlled. It means that it becomes.

Accordingly, there is a need for biocide compositions for reverse osmosis membranes that inhibit the growth of Bacillus bacillus and other microorganisms that damage membranes, as well as methods of preventing biological growth in such systems.

Accordingly, it is a primary object of the present invention to provide safe and effective biocide compositions for use in reverse osmosis water purification systems, and methods of using said compositions.

Another object of the present invention is to provide a biocide composition for use in reverse osmosis water purification systems, as well as a method of using the composition, that does not damage any commonly used membranes.

Yet another object of the present invention is to compare the scale # drug with
Biocide compositions for reverse osmosis water purification systems and methods of using the compositions are provided.

In accordance with the above object, the biocide composition of the present invention is a combination of at least one methylthio-s-triazine and iodine. Unlike chlorine, iodine is used
It has been surprisingly found that iodine does not damage all commonly used membranes. Additionally, iodine is highly effective as a fungicide. Among the methylthio-8-triazines, 2,4-bis(isopropylamino)-6-methylthio-8-triazine [Olb-a-Geigy Company, Inc.
2-(t-butylamino)-4-(ethylamino)-6-methylthio-di-triazine (commercially available as Prometryne from Giba-Gefgy Corporation) and 2-(t-butylamino)-4-(ethylamino)-6-methylthio-di-triazine (from Giba-Gefgy Corporation); -utr7ne)]
The inventors have found that combinations with are particularly effective in the compositions of the invention.

The inventor has further found that the compositions according to the invention are particularly useful as soaking agents, and also for use as biocides in reverse osmosis systems. As used herein, the term "Pickli" refers to a composition or substance that regulates the transport of a reverse osmosis membrane cartridge. When a reverse osmosis membrane is left to dry,
Particularly susceptible to damage such as cracks. Therefore, the installation is carried out by encasing the membrane in an installation liquid. If the above-mentioned membrane is simply packed in water, there is a risk of biological growth. Therefore, the membrane is usually packed in an aqueous solution of formaldehyde and glycerin.

Since the high toxicity of formaldehyde is well known, the shortcomings of prior art immersion liquids are obvious.

The inventor has found that the biocide composition of the invention in aqueous solution is a highly effective soaking agent. Therefore, another first object of the invention is to provide a safe solution for soaking reverse osmosis membranes. 0 Iodine is a known fungicide and is described, for example, in U.S. Pat.
No. 22,882, it is used as a food additive. Additionally, iodine can be added to various algicidal substances such as prometryms.
) and Terbutryns are also known for use in disinfecting swimming boots StV. Regarding this point, Nilinson
``Untied Algaru Suspensions for Iodine - This in 7 Extended Swimming''
Pools (Antlalgal 5nbatanae
s for engineering-Disinfsot@d S
Wi! Illying Pools) J, Applied Society and Environmental Microbiology (Mupp1.!l!nviron0Miarob
oL), Mar. 34, Dec. 1917, pp. 815-822. However, there has never been any suggestion regarding the use of eye drops in contact with reverse osmosis membranes. In fact, as noted above, it was previously thought that halogens of any kind could not be used in contact with reverse osmosis membranes, since chlorine is well known to degrade the quality of such membranes. . Since chlorine is the most commonly used halogen as a disinfectant or disinfectant, and is certainly the cheapest halogen, those skilled in the art of reverse osmosis understand that all halogens can damage membranes. Therefore, one would naturally assume that any halogen cannot be used in contact with the membrane.

Furthermore, it is well known that polyamides are extremely sensitive to oxidizing agents. Since iodine is known as an oxidizing agent, one skilled in the art would not even think of using iodine in a reverse osmosis system.

The present invention therefore relies in part on the surprising discovery that iodine has no adverse effect on all of the commonly used reverse osmosis membranes and that iodine can therefore be used for said purpose. It is based on

Furthermore, the inventors have found that the presence of triazine as an algaecide unexpectedly enhances the bactericidal action of iodine, so that less iodine has to be used than would normally be expected to be necessary. Ta. That is, there is a complementary effect between triazine and iodine.

The foregoing objects and other objects and advantages of the present invention include:
I believe this will become clear from the explanation below.

The present invention is based on a composition comprising at least one methylthio-s-triazine and iodine, said composition being used in an amount sufficient to provide the desired fungicidal action. The inventors have found that a preferred ratio range that provides the desired biocidal effect is about 105 F of methylthio-s-triazine in about 250 gallons of water containing the scale inhibitor used. -~about 1202 and iodine about 0.51 to about 10? It is. That is, mixing the scale inhibitor and biocide in the same mixing tank and then metering the combined solution into the feed water to the reverse osmosis water purification system at the desired feed rate of the scale inhibitor. provided. The concentration of biocide is sufficient to provide the desired effect at any commonly used feed rate. Accordingly, per 600 gallons of line fishing 2271-6 (600 gallons) mixed with the scale inhibitor described in our above-mentioned U.S. Pat.
The compositions of this invention in the proportions described above are effective when metered into feed water at about 48 tons (t gallons).

Example 1 Preferred compositions and preferred ratio ranges are shown below.

Ingredients Amount Promethrin (From
etryne) 5-60ft Chilbutrin (T
erbutryne) 5-60? Iodine
Since 0.5-101 promethrin and tilbutrin are poorly soluble in water, it is desirable to first dissolve the composition in a suitable inert solvent. As used herein, inert means not reacting with the components of the composition;
Furthermore, it refers to any solvent that is safe for use in a reverse osmosis water purification system. The most suitable such solvents are lower alcohols, ie alcohols of 1 to 5 carbon atoms. The most preferred alcohol from the standpoint of safety in use is ethanol. On the other hand, since ethanol is quite expensive, isobutyl alcohol is preferable from the viewpoint of adjuvant properties. In use, the above proportions of the composition are dissolved in about 0.4 g (tbind) of isobutyl alcohol to form a concentrate suitable for transport to the equipment site. next,
Add this concentrate to about 757 gallons (about 200 gallons) to about 9 gallons of water.
45.13 (approximately 250 gallons and well scale inhibitor mixed in a mixing tank.

Prometrine
15ff Terbutryne
151i' iodine
2 Noisopropyl Alcohol 1 Bind (approximately
50 gallons) and metered into the feed water to the unit at a rate sufficient for the scale inhibitor.

Gulf Coast, Texas
), the above composition was used in a polyimide membrane reverse osmosis water purification system installed on a drilling rig located offshore.
No observable biological growth occurred over a period of more than 10 months.

Example 3 Approximately 0.4 liters for approximately 946-13<250 gallons of water
When the composition of Example 2 diluted at a ratio of (tbind) was used to store polyimide reverse osmosis membrane cartridges prior to installation in the unit, no observable biological growth was observed.

Furthermore, the inventors have also discovered that propionic acid can be used as a solvent for potassium alcohols.

When propionic acid is used, it has the function of a solvent and an antibacterial agent (ie, active against Bacillus bacillus).

Example 4 When propionic acid is used, the preferred range of proportions is as follows.

Ingredients Amount Prometryne 5A'
60tTerbutryne
5-605' Iodine 0.
5~105I propion! ! 1 quart (approx. 0.9l)
The concentrated composition is added to about 94 ml of water to be metered into the feed water.
62 (approximately 250 gallons).

Example 5 Ingredients Amount Prometryne
15P Tilbutrin (Terbutrue)
15 f iodine
2-41 Sodium Iodide, Potassium Iodide, or Ammonium Iodide (The sum of 0.2ff iodine and iodide shall be less than 41) Propion 9 1 quart (approximately 0.51)
The concentrate is dissolved in approximately 250 gallons of water and metered into the feed water. Alkali metal iodide or ammonia iodide helps dissolve iodine and decomposes to provide free iodine.

Example 6 Approximately 0.41 (t) for approximately 946A (250*ron) of water
Using the composition of Example 5 diluted in the proportion of
Polyimide reverse osmosis membrane cartridge before installation in the unit.
When the fish were stored, no observable growth or growth occurred.

From the foregoing, it is clear that the above objectives are successfully achieved. Although the present invention has been described in accordance with preferred embodiments, it will be obvious to those skilled in the art that the present invention can be practiced with various modifications as long as they fall within the scope of the claims set forth above.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a typical reverse osmosis membrane assembly of the prior art. FIG. 2 is an explanatory diagram of a typical conventional reverse osmosis water purification system. 12... Semipermeable membrane; 14... Polymer matrix; 1
6... Central porous support body; 26... Mixer; 32.
...Cartridge filter: 36...Reverse osmosis device.

Claims (1)

[Claims] 1,(α)2,3-bis(isopropylamino)-6-
Methylthio-s-triazine and bilayer (t-butylamino)-4-(ethylamino)-6-methylthio-s-
A composition comprising at least one compound from the group consisting of triazines and (b) iodine in (c) a reactive inert solvent is added to 200 to 2 gallons of water.
Dissolve the resulting solution in 50 gallons (approximately 946 L) and meter the resulting solution into the feed water to a reverse osmosis water purification system at a rate sufficient to provide a biocidal effective concentration of the composition. A method of preventing biological growth in a reverse osmosis water purification system comprising providing. 2. The above composition contains 5 to 60 g of 2,4-bis(isopropylamino)-6-methylthio-s-triazine;
2-(t-butylamino)-4-(ethylamino)-6
- 5-60 g of methylthio-s-triazine and 0 iodine
．． 5 to 10 g. 3. The above composition contains 15 g of 2,4-bis(isopropylamino)-6-methylthio-s-triazine and 2-
The method according to claim 2, comprising 15 g of (t-butylamino)-4-(ethylamino)-6-methylthio-s-triazine and 2 g of iodine. 4. The method according to claim 1, wherein the solvent is a lower alkyl alcohol. 5. The method according to claim 4, wherein the alcohol is ethanol or isopropanol. 6. The method according to claim 1, wherein the solvent is propionic acid. 7. The method of claim 2 further comprising about 1 quart (about 0.9 liters) of propionic acid. 8. The method of claim 3 further comprising about 1 quart (about 0.9 liters) of propionic acid. 9. The method of claim 1 further comprising the step of mixing said composition with a scale inhibitor before said step of metering. 10. The method of claim 1, wherein a portion of said iodine is replaced by an alkali metal iodide or ammonium iodide. 11. The method according to claim 1, wherein the reverse osmosis system includes a polyamide membrane. 12, (a) 2,3-bis(isopropylamino)-6
-Methylthio-s-triazine and 2-(t-butylamino)-4-(ethylamino)-6-methylthio-s
- at least one compound of the group consisting of triazines; (b) iodine; (c) in a reactive inert solvent; A method of preserving a reverse osmosis membrane for use in a reverse osmosis water purification system, comprising soaking the membrane cartridge with a sufficient amount of solution. 13. The method according to claim 12, wherein said reverse osmosis system includes a polyamide membrane. 14, (α)2,3-bis(isopropylamino)-6
-Methylthio-s-triazine and 2-(t-butylamino)-4-(ethylamino)-6-methylthio-s
- A biocide composition for use in a reverse osmosis water purification system, comprising at least one compound of the group consisting of triazines; (b) iodine; and (c) propionic acid. 5-60 g of 15,2,4-bis(isopropylamino)-6-methylthio-s-triazine and 2-(t-butylamino)-4-(ethylamino)-6-methylthio-
15. A composition according to claim 14, comprising 5 to 60 g of s-triazine and 0.5 to 10 g of iodine. 15 g of 16,2,4-bis(isopropylamino)-6-methylthio-s-triazine and 2-(t-butylamino)-4-(ethylamino)-6-methylthio-s-
16. A composition according to claim 15, comprising 15 g of triazine and 2 g of iodine. 17. The composition of claim 14, wherein a portion of said iodine is replaced by an alkali metal iodide or ammonium iodide. 18. Claim 14 in combination with a scale inhibitor
Compositions as described in Section. 19. The composition according to claim 18, wherein the scale inhibitor comprises polyacrylic acid. 20. The composition of claim 19, wherein the scale inhibitor comprises polyacrylic acid and phytic acid. 21. The composition according to claim 14, wherein the reverse osmosis system includes a polyamide membrane.