DE2656465A1 - METHOD FOR DISINCLUDING LIQUIDS - Google Patents

Abstract

In a process for sterilising liquids, in particular drinking water and service water, using silver ions, the sterilisation takes place rapidly, without complicated apparatus, without hazard to health, in an economical manner and with a reliable long-term effect being obtained even in the case of highly branched pipe systems in that the liquid to be sterilised is brought into contact with a cation-exchanger composition prepared with silver. The cation-exchanger composition is preferably a macroporous cation exchanger having weakly acidic substitutable groups which are complex-forming with heavy metal ions and have a high selectivity for silver ions.

Description

Process for the sterilization of liquids

The invention relates to a method for disinfecting liquids, especially of drinking and industrial water, using silver ions.

Piping systems and apparatus as well as the liquids contained therein, especially drinking and industrial water contain a mostly tolerable number different germs. In the case of stagnant flow, warming or an increase in volume, as well as in vessels with longer dwell times, such as filters, softening systems, Pressure increase systems etc. can establish germs and so-called colonies form. Liquids and the surfaces they wet therefore require im Health concern of disinfection when these fluids are in contact with humans or animals come into contact, in particular are intended for consumption.

The disinfection or sterilization of liquids, especially of Drinking and service water, as well as the sterility of apparatus and pipe systems and facilities for the transport, storage or treatment of such liquids, occurs predominantly through substances with a very high oxidizing power. One Chlorine has achieved particular practical importance as a disinfectant, namely as chlorine gas, as a compound of hypochlorous acid, such as calcium or sodium hypochlorite, as well as chlorinated lime. Chlorainines are also used, including chlorine dioxide gas with its strong oidation power is used more often. Of practical importance is also the use of ozone because it is the most powerful one that can be used It acts as an oxidizing agent with a germicidal effect, the oxidizing power of which is 1.4 times higher than elemental chlorine. Made with the help of mercury vapor lamps ultraviolet light is also suitable, but it only has direct exposure germicidal effect of the microorganisms to be killed. In the end is also to mention that occasionally bromine, iodine, potassium permanganate as well as various Peroxide compounds are used for disinfection.

The oxidizing chemicals and gases can practically only be found in the Drinking, industrial water and swimming pool water treatment can be used. For the They are not suitable for the food and beverage industry. For with chlorine products or other oxidizing chemicals disinfected water must be done with the help of a suitable device, usually activated charcoal filter, the existing excess of disinfectant can be removed immediately at the point of use. The ones used oxidizing chemicals and gases are consistently more or less complex and expensive metering and / or monitoring devices. Even the preparation of individual ones Substances, e.g. B. ozone or chlorine dioxide, requires very complex and expensive facilities. A significant problem is also the storage of the mostly for humans and animals as well for the environment in concentrated form are very dangerous products. In addition The widespread use of chlorine products inevitably makes one uncomfortable perceived impairment of taste with itself. The pH value, which is here mostly is above 7.0, also has a disadvantageous effect, because it causes the oxidizing Effect decreases sharply; When using ozone in drinking water disinfection, which does not produce any odor nuisance, the problem is that Ozone slowly breaks down in the water and so the disinfecting effect in widely ramified Line networks does not persist.

A so-called post-chlorination is therefore often used as a safety measure demands.

As already mentioned at the beginning, are used for the disinfection of water silver ions have also been used (Degrémont, manual, water treatment, wastewater treatment, Bauverlag GmbH, Wiesbaden and Berlin, 1974, pages 246, 614) This is the case is an electrolytic sterilization process (oil dynamics) in which two electrodes are immersed in the water to be treated, of which the The anode is made of silver and the cathode is made of carbon or stainless steel. The two electrodes connected to a direct current must be in one place be appropriate where the water is in a turbulent state, e.g. B. within a pipe through which the water to be treated flows. With this well-known Procedures must take into account the statutory maximum amounts of silver (USA 50 pg / l, BRD 10021g / 1, CH 200 rg / l). To at these low concentrations To obtain a safe disinfecting effect, long contact times, e.g. B. up to 6 h, when using 25 pgll, for killing E-Coli, available stand. This procedure therefore requires more or less large intermediate vessels, to ensure the necessary long contact times. In addition, the Use of this procedure is very controversial (Degrmont, Handbuch, 5. 246).

The invention is based on the object of a method of the above to provide designated genus, with which the disinfection of liquids with the help of silver ions very quickly, without expensive equipment and without health hazards can be carried out in an economical manner, even with widely ramified ones Line systems a safe long-term effect is to be achieved.

According to the present invention, this object is achieved by that the liquid to be sterilized with a cation exchange mass prepared with silver brings in contact.

According to the basic idea of the present invention, very high Concentrations of silver ions in a suitable form on the very large inner surface provided by cation exchange masses, whereby the necessary for disinfection Contact time to a fraction of that for the known electrolytic sterilization process required residence time can be reduced.

This ensures that the treated liquid will be replenished with germs prevented, because the cation exchange mass prepared with silver at the same time Releases or can release silver ions into the liquid in permitted amounts. the Liquid itself also transports these silver ions to distant locations in widely ramified line systems. Because of the short contact time, relatively Small-scale, simple apparatus constructions are used.

For the successful implementation of the method according to the invention the selection of a suitable cation exchange compound is of crucial importance. Particularly favorable results are achieved when a cation exchange compound is used macroporous cation exchanger with weakly acidic exchange-active groups, which are complex-forming with heavy metal ions and have a high selectivity towards silver ions have, is used. Due to the high affinity of the exchanger used for silver, as well as its weakly acidic character, the silver ions are avoided quickly eliminated by other ions present in the liquid to be treated. exchanged and are released into the liquid, where they may contain an unacceptably high concentration of silver ions can evoke.

In principle, any cation exchanger in which the silver ions can be attached to active exchange groups, the carrier function for the Meet silver.

The method according to the invention can be carried out with particularly favorable results if a macroporous synthetic resin based on polystyrene with a pore size of at least 100 Å, preferably between 300 and 500 Å, and a rounded grain shape, preferably spherical shape, with a grain size between 0.3 and 1 , 2 mm is used. Such an acidic polystyrene exchanger can have the following chemical structure An important prerequisite for the process according to the invention is the highest possible silver concentration in the exchange resin. The silver concentration in the cation exchange material is advantageously 150 to 200 g / l. Higher silver concentrations are of course also suitable. In pursuance of the inventive idea, the total capacity is to be aimed for, this is about 1.8 to 2 eq / l exchangers for exchangers with strongly acidic exchange-active groups and 4 eq / l exchangers for exchangers with weakly acidic exchangers, and around the preferred macroporous weakly acidic exchangers 2.8 eq / l exchanger.

The preparation of the cation exchange mass is expediently carried out by that the silver as an aqueous solution of a silver salt, preferably silver nitrate or silver sulfate incorporated into the cation exchange mass.

There is a very important advantage of the method according to the invention in that it allows the use of the continuous process in which the Liquid to be sterilized in a continuous flow through a prepared Cation exchange mass formed bed can flow. The contact times that can be achieved here are completely sufficient to safely disinfect the liquid to be treated. The available compared to the known electrolytic sterilization process At least 40,000 times the concentration of silver ions allows throughput speeds of about 100 m / h, with a sterilization effect is achieved that of the known electrolytic process contact times between 10 and 20 h when using the would require legally permitted maximum concentrations.

The process according to the invention can be carried out at all temperatures in which the liquid to be treated is in the liquid phase, with water and normal pressure, for example in the range between 0 and 100 ° C., preferably but between 10 and 20 ° C, because normal drinking and service water is usually used occurs in this temperature range. However, higher temperatures promote the disinfection effect of silver.

In one embodiment of an expedient procedure the liquid to be sterilized is allowed to pass through one of the prepared cation exchange mass flow formed fixed bed filter. If, however, higher flow velocities can be allowed, in an advantageous further embodiment, the Process can also be carried out in such a way that the liquid to be sterilized is through a fluidized bed filter formed from the prepared cation exchange mass flow leaves. Both when using a fixed bed and also when using a fluidized bed Flow conditions can be proportionate depending on the throughput rate Use small-volume and structurally simple apparatus.

The method according to the invention can advantageously be used simultaneously with others desired exchange processes, e.g. WdibE for water softening by mail the liquid to be sterilized and possibly softened a cation exchange mass prepared with silver and other ion exchange mass formed mixed fixed bed filter flows.

When using germ filter cartridges there is a risk that the germs filtered off through the filter cartridge to a certain extent mixed. This phenomenon can be stopped in the pursuit of the inventive idea, when the liquid to be sterilized is passed through a germ filter cartridge, in its filter layer Cation exchange mass prepared with silver is arranged distributed, flow leaves. However, the process can be carried out using commercially available filter cartridges also perform in such a way that the liquid to be sterilized is passed through a germ filter cartridge, the exit surface of which consists of a layer of cation exchange material prepared with silver is covered, lets flow.

The invention is explained below with reference to method examples and the accompanying drawings explained in more detail. Examples 1 and 2 relate to the preparation of the ion exchange material used. The drawings illustrate Schematic sectional representations of exemplary embodiments for the implementation of the apparatus of the method according to the invention. 1 shows a sterilization container with a fixed bed of the prepared cation exchange mass, FIG. 2 shows a disinfection container with a fluidized bed arrangement for the prepared cation exchange mass, Fig. 3 a container for simultaneous disinfection and other exchange treatment of liquids, FIG. 4 shows a filter cartridge with a prepared filter cartridge distributed in the filter material Cation exchange compound, and 5 shows a commercially available filter cartridge with an applied layer consisting of prepared cation exchange material.

In the seen from Fig. 1 cylindrical pressure vessel 1 is located On a flow-permeable floor 2, a bed 3 of prepared granular synthetic resin compound.

The base 2 can be designed as a nozzle or sieve base. The too disinfecting liquid enters via the inlet. 4 at the top of the pressure vessel 1 and leaves this after it has flowed through the bed 3 and the bottom 2 below via the drain 5. The selected flow direction from top to bottom ensures that that the bed 3 obtained as a fixed bed even at higher flow rates remain. Of course, a distributor tray can od above the bed 3. Like. Be arranged that the entering liquid evenly over the cross section of the pressure vessel 1 distributed. The flow can also be from bottom to top, provided that the flow rate is kept low enough to cause turbulence to prevent the fixed bed.

The illustrated in Fig. 2 cylindrical pressure vessel 6 is above and provided with a bottom 7 or 8 at the bottom.

Both floors can in turn be designed as nozzle or sieve floors be. In this case the flow takes place from wlien upwards by the one to be sterilized Liquid enters via the inlet 9 below and the pressure vessel 6 via the outlet 10 above leaves. At rest, i.e. when there is no flow, the made of prepared synthetic resin bed on the lower floor 7, with their upper limit roughly by the dash-dotted line 11 indicated is. The originally existing fixed bed begins to expand as soon as the pressure drops of the flowing liquid in the bed by increasing the flow velocity the bulk weight of the prepared solid based on the unit area is reached. If the flow velocity is increased further, the transition from the fixed bed takes place to the fluidized bed, also called fluidized bed. This fluidization creates a state in which the bulk particles are in lively movement and mixing, but remain in the balance.

Fig. 3 shows an arrangement similar to FIG. 1, in which in one Pressure vessel 12 has a fixed bed layer on a lower nozzle or sieve tray 13 14 rests.

The granular components of this fixed bed layer are shown in the drawing symbolically reproduced, the blackened particles being those prepared with silver Represent cation exchange mass, while the non-blackened particles the for represent another exchange process required ion exchange mass.

The cation exchange mass prepared with silver becomes that for the softening or another exchange process necessary ion exchangers directly placed in the pressure vessel 12. During the rewinding process, which is contrary to the Figure takes place in the direction of the arrow, a large proportion of the prepared drops Cation exchange mass on the bottom of the exchange bed. Part of the groomed Exchange mass is distributed according to the grain size or the specific Weight in the exchanger bed decreasing from bottom to top. Through this distribution in in the bed 14 is a mixed bed in which through the spread of the cation exchange mass prepared with silver prevents the contamination of the entire exchanger bed is prevented. The pressure vessel is in normal operation from the liquid to be treated flowed through from top to bottom, which over the Inlet 15 enters and leaves the container via outlet 16.

From Fig. 4 is a substantially hollow cylindrical germ filter cartridge 17 from the liquid to be sterilized in the direction of arrows 18 in is flowed through in the radial direction. The sterilized and filtered liquid will withdrawn via the cavity 19. In the filter layer 20 granular is prepared with silver Cation exchange mass arranged in a distributed manner, like the grains 21 shown illustrate. These grains 21 are used in the manufacture of the filter cartridge incorporated.

The grains 21 prevent the germs from flowing through in the direction of flow grow through the filter cartridge. Rather, the germs are in the filter layer 20 filtered off and die on contact with the synthetic resin grains prepared with silver 21 from.

The commercially available germ filter cartridge 22 shown in FIG. 5 has also essentially the shape of a hollow cylinder. Also this cartridge will flows through in the direction of arrows 23 in the radial direction. In the inner cavity of the filter cartridge 22 and coaxial therewith is one using one with silver The hollow cylindrical insert 24 produced from the prepared cation exchange mass arranged. This forms the one that covers the exit surface 25 of the filter cartridge 22 disinfecting layer.

The filtered and sterilized liquid is collected via the inner collecting space 26 of the insert 24 discharged.

Example 1 One of the amount of cation exchanger to be prepared in Ratio 150 g of metallic silver per liter of exchange mass associated amount Silver nitrate was dissolved in softened water with stirring at 20 ° C in a reaction vessel dissolved to a 5% solution. Then, with constant stirring, the amount of a macroporous cation exchange compound based on polystyrene held ready (Lewatit TP 207 from Bayer AG) with a grain size between 0.3 and 1.2 mm and one Pore size between 300 and 500 i sprinkled into the aqueous silver nitrate solution. Stirring was continued until the silver detection in the liquid was negative, d. H. all the silver had passed into the cation exchange mass. After that it was the cation exchange mass through a simple sieve filter with a mesh size from 0.05 to 0.1 mm filtered off and rinsed with an approx. 5% saline solution until the nitrate detection in the process was negative. The cation exchange mass prepared in this way until further use in a closed, waterproof plastic container stored to avoid drying out.

Example 2 One of the amount of cation exchanger to be prepared in Ratio 200 g of metallic silver per liter of exchange mass associated amount Silver sulfate was dissolved in softened water with stirring at 20 ° C in a dissolving container dissolved to an approx. 5 dough solution. The amount of macroporous to be prepared Cation exchange mass according to example 1 was in a reaction vessel submitted. The silver sulfate solution was then passed over for so long with a circulating pump the cation exchange mass was pumped until the silver detection was negative in the course of the process. The liquid was then drained off. The cation exchange mass was then from the dissolving vessel over the circulation pump with an approx. 5 saline solution rinsed until the sulphate detection was negative in the course of the process.

The cation exchange mass prepared in this way was until further Use stored in a closed, waterproof plastic container, to avoid drying out.

Example 3 A commercially available water softener (compact softener Type 19-70, made by Plasworld Inc, Racine, Wisc., V.St.A., With a glass fiber reinforced Polyester pressure vessel, make Structural Fibers V.St.A. and a 5-step Control valve made of a glass fiber reinforced polyphenylene oxide-polystyrene mixture, Make Autotrol) with 19 1 ion exchange compound for water softening Connected to the public drinking water network, filled with water and for function control put into operation. The apparatus was then left to stand without flow for 5 days. After this period had elapsed, the control valve was dismantled, 1.5 l of ion exchange mass syphoned out and 1.5 l of cation exchange material prepared according to Example 1 replaced. After reattaching the control valve, the prepared The cation exchange mass was backwashed well and the apparatus started up again. The water temperature averaged around 20 OC. In the table below 1 are the results of the test carried out over a period of about 7 months sequence is reproduced.

TABLE 1 1 2 3 4 5 6 7 8 9 10 11 Verse rain. Operation standstill amount of water total sample total number of kilograms / ml silver Day total total l / h m³ no hh ser untreated water Welchwas- delt ser µg / l 0 1 5 6.5 115.0 350 2.3 2 6 1 14.5 134.0 180 3.7 27 633.5 1 33 28 2 655.75 2 7 31 727.75 32 3 37.5 799.75 180 7.88 33 47.25 812.25 180 15.2 34 4 143.25 480 63.2 38 828.50 39 3 31 4 50 53 849.50 5 0 6 82 62 1184.50 7 33 8 135 81 5 144.25 1400.50 300 63.5 TABLE 1 1 2 3 4 5 6 7 8 9 10 11 Verse rain. Operation standstill amount of water total sample total germ count / ml silver Day Total Total 1 / h m³ No. tap water Welch- halt im kungen h untreated water soft water ser µg / l 88 147.5 1832.50 180 64.2 90 91 1880.0 9 202 94 6 150.0 1896.0 180 64.6 95 151.0 1969.75 180 64.8 97 155.0 1994.25 180 65.5 98 2037.75 101 2053.75 11 11 12 76 103 174.0 2117.0 180 68.9 104 2145.5 174 178.25 4065.5 180 69.7 14 59 46.3 3 15 34 35.2 4 175 188.25 4086.5 180 71.5 179 7 19 600 20 28 24.2 203 197.25 5142.5 180 73.2 209 197.25 5286.5 21 1 22 42 EXAMPLE 4 For comparison purposes, parallel to the test procedure according to Example 3, a second water softener, exactly corresponding to the first, with 19 l of ion exchange compound for water softening was connected to the same public drinking water network and started up as in Example 3. The apparatus was then left to stand without flow for 8 days. The test program was then started, the sequence of which is shown in Table 2 below. For this series of comparative tests it is essential that the water softener only contained the ion exchange material for water softening, but not cation exchange material prepared with silver. As in the test program according to Example 3, the bacteriological investigations were carried out by the Veterinary Bacteriological Institute of the University of Zurich.

TABLE 2 1 2 3 4 5 6 7 8 9 11 Vers. Reg. Operation Standstill Water Total Sample Total germ count / ml Comments Day total total amount m³ no. hh 1 / h water water 0 1 8 1.0 204.0 300 0.3 10 4.5 251.5 180 1.1 11 267.5 10 400 13 1 14 6.75 284.0 180 1.5 16 7.75 326.5 180 1.68 17 11.75 342.5 180 2.4 20 406.5 11 11 13 440 22 458.5 23 30.75 180 5.8 62 35.00 1394.5 180 6.72 16 15,300 2 17 2,300 3 63 45.0 1415.5 180 8.52 67 2 1499.75 18 495 20 600 91 54.0 2075.75 180 10.2 97 2212.0 21 1 23 910 In Tables 1 and 2, the test days are listed in column 1. The test days 209 in Table 1 and 97 in Table 2 are identical calendar days. In column 2 of Tables 1 and 2, the regenerations carried out are given in consecutive numbering. The regeneration processes were carried out in order to reactivate the ion exchange mass loaded with hardness-forming cations (calcium and magnesium ions) for an operating cycle. A saline solution of approx. 10 violins was used for this. Controlled by a timer and a program roller, the following operations took place during each regeneration process.

1. Backwash.

The softener was filled with a stream of water from below flows through the top and whirled up so that dirt particles, which during the preceding Were entered in the establishment, were flushed out.

2. Soak in brine.

Using a water-jet suction device, the one in the salt container was removed saturated saline solution sucked in, with the motive water of the ejector on the for regeneration required concentration of 10% diluted and slowly over the ion exchange mass is rinsed.

3. Rinse slowly.

The excess saline solution was removed with the motive water of the aspirator slowly washed out of the ion exchange mass.

4. Quick rinse.

The regeneration solution that was still present was then replaced with a strong stream of water rinsed out quickly.

Through the regeneration processes, the silver ion concentration became not affected in the course of the experiment according to Example 3.

In columns 3 and 4 of Tables 1 and 2 are the operating times or the downtimes are listed in hours. This is the continuously accumulated total operating times and downtimes. In column 5 of both In the tables, the specified amount of water is the instantaneous flow rate during operation or when taking a sample.

In contrast, column 6 shows the total amounts enforced. In column 7 of both tables, sampling numbers for the germ count are assigned. Column 8 of the tables shows the results of the germ count in tap water the water softener, d. H. in untreated drinking water, listed while from column 9 of the tables the results of the germ counts in soft water after Emerge from the water softener. From column 10 of Table 1 are the measured The silver content of water samples can be seen, which is in the direction of flow after the water tester were drawn. The numbers listed in comment columns 1 ~ 1 of the tables have the following meanings.

Table 1: Note 1: Apparatus installed and filled with water Note 2: Apparatus opened and cation exchange mass prepared with silver filled in Comment 3: Sampling after one minute flow time Comment 4: Sampling after a flow time of 10 min Table 2: Comment 1: Apparatus installed and filled with water Note 2: Sampling after 1 min flow time Note 3: Sampling after 10 min flow time.

Tables 1 and 2 demonstrate on the one hand how with the aid of the invention Process effectively prevents an inadmissibly high level of contamination of the ion exchange bed becomes, and on the other hand a conventional ion exchange bed quickly in such a Measures contaminated that the water that has passed through the ion exchange bed does not can be called more than drinking water. Since the test days in the tables 209 (Table 1) and 97 (Table 2) mean the same calendar day, it can be seen that after an operation and downtime longer by 112 days when in use practically no contamination of the prepared cation exchange composition according to Example 3 of the exchanger bed has taken place during the test sequence according to the example 4 using an exchange bed containing no silver preparation is so contaminated that in the soft water the permitted number of germs is 300 / ml by far has been exceeded. As can be seen from Table 2, the aforementioned has been approved The number of germs exceeded after just 11 days of the experiment. Particularly serious occurs the difference between the test procedure according to Example 3 and the comparative test procedure according to Example 4, if the test days 174 (Table 1) and 62 (Table 2) which in turn corresponded to the same calendar day. The I measurements on these trial days showed that the water out not that The prepared apparatus was more of the quality of cloacal water, during which the Apparatus containing silver preparation absolutely clean and impeccable drinking water delivered.

When using a cation exchange material prepared with silver according to Example 2 comparable results were obtained.

- patent claims - L e r s e i t e

Claims (11)

Method for disinfecting liquids, in particular of drinking and industrial water, using silver ions, characterized in that the liquid to be sterilized with a cation exchange mass prepared with silver brings in contact. 2. The method according to claim 1, characterized in that the cation exchange mass a macroporous cation exchanger with weakly acidic exchange-active groups, which are complex-forming with heavy metal ions and a have high selectivity is used. 3. The method according to claim 2, characterized in that the cation exchange mass a macroporous synthetic resin based on polystyrene with a pore size of at least 100 Å, preferably between 300 and 500 R, and rounded grain shape, preferably Spherical shape, with a grain size between 0.3 and 1.2 mm, is used. 4. The method according to any one of claims 1 to 3, characterized in that that the silver concentration in the cation exchange mass is 150 to 200 g / l. 5. The method according to any one of claims 1 to 4, characterized in that that the silver as an aqueous solution of a silver salt, preferably silver nitrate or silver sulfate incorporated with the cation exchange mass. 6. The method according to any one of claims 1 to 5, characterized in that that the liquid to be sterilized is continuously passed through a the prepared cation exchange mass formed bed can flow. 7. The method according to claim 6, characterized in that the The liquid to be sterilized by means of one of the prepared cation exchange mass formed fixed bed filter can flow. 8. The method according to claim 6, characterized in that the The liquid to be sterilized by means of one of the prepared cation exchange mass formed fluidized bed filter can flow. 9. The method according to any one of claims 1 to 5, characterized in, that the liquid to be sterilized by a cation exchange mass prepared from with silver and flow mixed fixed bed filter formed by other ion exchange bulk. 10. The method according to any one of claims 1 to 5, characterized in that that the liquid to be sterilized through a germ filter cartridge, in the filter layer Cation exchange mass prepared with silver is arranged distributed, flow leaves. 11. The method according to any one of claims 1 to 5, characterized in that that the liquid to be sterilized through a germ filter cartridge, the outlet surface is covered by a layer of cation exchange mass prepared with silver, lets flow.