DE3124433A1 - Method for the sterilisation of liquids - Google Patents

Abstract

A method for the sterilisation of liquids, especially of water, is proposed and entails the non-sterile liquid being contacted with a solid to whose surface substances with antimicrobial activity are chemically bonded, predominantly covalently. The substances with antimicrobial activity which are chemically bonded to the solid within the scope of the method are moreover active in the bonded state. This method is not only straightforward to carry out, it is particularly distinguished by economy and by the fact that no unpleasant byproducts which are a possible risk to humans, animals and the environment are produced.

Description

Process for the sterilization of liquids

The invention relates to a method for disinfecting liquids, especially of water and aqueous solutions.

Securing the drinking and industrial water supply requires increasingly the exploitation of new raw water sources, in particular the use of bacteriologically imperfect and heavily contaminated with organic pollutants Surface water. There are new biological ones for the preparation of such RohsZäiser or chemical-biological technologies necessary. Due to this processing method, but also because of the higher germ load of the raw qas: er, they become extensive Disinfection measures are becoming more and more important.

For such disinfection measures to disinfect drinking and In principle, process water can use physical methods such as UV radiation, X-ray or gamma emission or heat are used; these are for the large-scale However, application is not satisfactory and, above all, too aurwendic. Greatest Classical Importance have only acquired the chemical methods based on the application of strong oxidizing agents such as chlorine, chlorine dioxide and ozone are based as hygienically optimal disinfectants. All of these gases are highly reactive, but also highly toxic: and corrosive. When using chlorine or chlorine-releasing compounds, the highest levels are created unwanted, toxic reaction products. The one with the accompanying organic substances On the one hand, the chlorine compounds formed in the water to be treated interfere with the biological treatment, on the other hand they are also toxic in pure water. Ozonation is clearly superior to chlorination in these points, so see Sect it more and more displaces the latter. Like chlorine dioxide, ozone has the disadvantage that it must be produced on the spot; Qs is many times more toxic as chlorine and in addition: 'a noen highly explosive. Verkeiun'j poses another problem of drinking water treatment plants themselves; mentioned in this context are the processes of biological oxidation with upstream chemical pre-oxidation. Another example is provided by the precoat filters, especially for the treatment of Swimming pool water. In the latter case, bacteriologically perfect water is required such high chlorine or ozone dosages that the MAK values above the water surface can be reached or exceeded.

This brief review of the prior art makes it clear that for the problem of disinfecting liquids, especially water, none optimal solutions and practices are available. The crucial problem of large-scale The main chemical definition used is toxicity of the disinfectant or the resulting reaction products.

The object of the invention is to provide a method for disinfecting liquids, especially of water, to protect the mentioned above Avoid disadvantages of existing processes and these processes also in terms of economy transfers; fft.

As a solution to this problem, the method according to the invention brings measures claimed in the claims.

Surprisingly, it has been found that the number of germs of high germ content Liquids or waters, which are passed through a fixed bed consisting of granular or fibrous, materials in loose or contiguous form on which there is Surface antimicrobial substances (w 4W-S 'chemically, especially covalently, were bound to be drastically reduced. The production of these carrier-bound, Antimicrobial substances (AMWS) is described in principle in OS 2922347. The way in which the action of germ killing by the carrier-bound : .MSRS when flowing through the fixed bed of germ-containing liquids or waters is not known. It is absolutely certain, however, that the germicidal Effect is not based on a Dpoteffekt, i.e. that the active ingredient gradually from the surface of the carrier material, for example by hydrolysis, split off and acts in a dissolved form. Example 2 makes this situation clear and confirmed with absolute certainty.

These observations described above represent a new breed for the disinfection of liquids or water, namely with the help of the carrier-bound AMWS, which can be technically applied in various ways. So are on the basis of these observations, for example, continuous or quasi-continuous Processes possible, the use of which is: volwiecTell, in large-scale processing of liquids e.g. in the special case of water can be seen.

Continuous processes are to be understood as those processes in which the germ-laden liquid is continuously passed through a layer of carrier-bound AMWS, for example a fixed bed, flows, killing the living germs or theirs Concentration is drastically lowered and the alz (killed germs at the outlet not, partially or completely discharged from the fixed bed with the liquid will. A quasi-continuous process would then be understood to mean that the same fixed bed germ filter is periodically backwashed to remove the germ-laden surfaces to clean the carrier-bound AMWS. In this case, for a system there would be at least two contact devices required, which are operated alternately and thus allow continuous plant operation.

In addition, there are also filters or small filters that can be operated discontinuously for the disinfection of liquids can be implemented in which the liquid to be disinfected more or less long titer of the layer or bed of carrier-bound AMWS stands:.

In principle, however, the application of the carrier-bound AMWS is for Liquid disinfection is not limited to these process variants. Much more any process implementation is conceivable in which the liquid to be sterilized with the carrier-bound AMWS over a more or less defined period of time is in contact. For example, under a more or less de @ inicrte period To understand 15 minutes in total, usually the contact times are between 1 millut: and 60 minutes. The effective contact time results from the antimicrobial activity the carrier-bound AMWS and the rX25 resistance of the respective germs.

The implementation of the liquid sterilization according to this new procedure has a multitude of extraordinary advantages over all known ones Process especially for trir. Water treatment. Require carrier-bound A S an exceptionally low active ingredient content, since the AMWS is only on the Surface of the solids, which should, however, be as large as possible, in an in usually a monomolecular arrangement is required. The active ingredient concentration on the surface can in fact be up to 100% depending on the degree of coverage.

On the other hand, with surprisingly low coverages, the Solid surfaces with chemically bound AMWS of 10%, for example, are excellent antimicrobial effects can be achieved. A sufficiently homogeneous one is important Distribution of AMWS molecules on the surface. It must also be used during the disinfection process AMWS are not continuously added, as is the case with conventional chemical methods the case is. D c The effect of the carrier-bound AMWS only expires when the offered surface more or less completely covered with dead germs should be. This implies that killed germs or got into the germ filter Dirt particles actually remain on the surface of the carrier-bound AMWS not rinsed off These processes can be avoided through structural design aes of carrier-bound AMWS existing germ filters. Provided it is also ensured that the layer of carrier-bound A.NWS from the Solid not by hydrolysis or other processes are replaced, extraordinarily long service lives are possible. The chemical and especially the @ Ydrolysis stability are a basic requirement of the discoloration, and with This basic prerequisite is that the SsWS binds appropriately to the solid surface absolutely guaranteed that s3shown in example 2 as an example. Thereby) L Q possible for the first time, AMWS with a particularly intensive effect. and especially wide Use spectrum of activity. Such AMWS are preferably organometallic compounds, which have the disadvantage of high toxicity for humans and animals and their application would be absolutely unthinkable in a dissolved form.

As carrier materials for the carrier-bound AMWS finuan solids primarily synthetic polymers such as polystyrenes, polyamides or polymethacrylates, natural polymers such as cellulose are used, but are also inorganic carriers such as glasses, ceramics, carbon e.g. in the form of carbon or activated carbon and others Solids can be used as carriers on which AMWS are chemically and, above all, hydrolysis-stable let bind. The shape of the solid is based in the main line on that. the largest possible geometric surface is available. This leads to spherological Particles with, for example, 0.5 mm in diameter, continuous and short fibers of about 10 / µm in diameter, cylindrical and tubular particles that are in disorder or orderly arrangement as well as in iOL! as well as interconnected form can be used.

In addition to the geometrical shape of the carrier materials, these must be the Have the property that functional groups are present on the surface or by appropriate chemical treatment can be generated to which the AMWS is bound in a hydrolytically stable manner with the formation of a chemical bond can be.

In the same way, it is necessary to produce the carrier-bound A.v-NS, that the AMWS to be coupled are responsible for the antimicrobial effect in addition to the one or more Group (s) still have at least one reactive group, which d e Coupling to the surface groups of the carrier material allows for mobility Increasing the AMVS on the surface can override its fixation on the surface a coupling component or a spacer can be expedient. Under Space-- is here to understand a molecule that increases the distance between the AMWS and the surface. Due to the chemically stable bond of the AbIWS to the solid surface is As already mentioned, it is also possible to use AMWS that are considered to be toxic apply, but an extraordinarily high antimicrobial wave and above all one have a broad spectrum of activity. These connections are, for example organometallic, in particular organotin and organic mercury compounds. The mode of action of such carrier-bound AMWS in the bound state in the Water disinfection and, above all, the proof of the stable bond to the surface the carrier materials is explained below with reference to three examples.

Example 1: An unloaded ion exchange resin was used as the carrier material used in the form of spheres with a grain size of 0.2-0.8 mm; this resin is involved it is one cross-linked with divinylbenzene Polystyrene. This Resin does not have any reactive surface groups a priori, a 1WS chemically to tie.

The required surface groups are treated for 24 hours with chloromethylme @@@@ ether and tin (IV) chloride in carbon tetrachloride at room temperature generated; This P action made the chloromethyl group reactive and capable of coupling Surface group introduced. At this surface group was in another Step p-aminophenyl mercury acetate as an antimicrobial substance (AMWS) Fixed via the amino group with the formation of an amine bond. The amine bond is considered to be extremely hydrolysestubi @. The tL action time was 48 h, as a solvent dioxane was used. For quantitative removal of excess, no bound AMWS, the beads were 72 h with tetrahydrofuran at normal pressure and Extracted room temperature in the Soxleth.

The antimicrobial effectiveness of those bound on the polystyrene beads Mercury compound was tested comparatively with untreated polystyrene. 100 g of the treated and untreated were each in a column and a Rerenenz column Polystyrene beads filled with an egg and covered with water containing bacteria. The germ concentration was 106 germs / ml. The following bacteria and fungi were used: Chromobacterium violaceunt, Micrococcus flavus, two unspecified Micrococci from Cologne Groundwater and Aspergillus niger. To various lines at the outlet of the Column, a liquid sample is taken from the suspension and a bacterial count is determined durchgcc rt.

It has been shown that no viable ones after 15 minutes of contact time More germs in the column with treated polystyrene were present. This demonstrates that the carrier-bound AMWS has a biocidal effect in a very short time.

After this experiment, in which the biocidal effect of the carrier-bound AMWS could be detected at shortest contact times, the experiment was carried out continuously with both columns. The volume flow of the same germ-laden Liquid chains were adjusted so that the contact time in each column was 30 Minutes. In this case, too, could in the course of the column with carrier-bound AMWS no longer detect any viable germs in the stationary state, while the number of rhymes in the flow of the reference column is almost identical to that of the feed @ was. The difference in the latter case is presumably due to the fact that some germs were retained in the filter.

Example 2: To ensure that the effect described in Example 1 of the carrier-bound AMWS actually depends on the action of the AMWS in the bound state takes place, the following further experiment was carried out. Prepared according to Example 1 Carrier-bound! WS in an amount of 100 g was used at room temperature for 14 days distilled water extracted in Soxleth. Part of the extraction liquid was mixed with a volume of equal volume of Standard I nutrient broth and with Chromobacterium violaceum inoculated as a test germ. Thereafter, at 30 ° C in the Bru cupboard 3 Taqe incubated. In addition, a comparative test was set up in which only the extraction liquid was replaced with distilled water. The germ growth beiczr Trials was completely identical to how through germ count has been proven. This means that there is reliable evidence that that the effect of the carrier-bound AfS according to Example 1 exclusively on the Effect of the AMWS in the bound state is based and not on a depot effect, i.e. a successive release of the active ingredient, as one might suspect, attributed to it is.

Example 3: In example 1 it was demonstrated that a germ-laden Suspension after flowing through a column in which there are polystyrene beads p-minophenylsilver acetate bound to the surface were found as AbNS, none contains more viable germs. In Example 2, it was demonstrated that the effect of the p-aminophenylmercury acetate bound on the surface of the polystyrene beads takes place effectively and exclusively in the chemically bound state. Hereinafter Example 3 is also intended to demonstrate the load-bearing capacity with suspension containing bacteria a column can be demonstrated in which the same polystyrene beads with p-aminophenyl mercury acetate bound on the surface, as in Example 1.

For this purpose, a closed circulatory system of a total of 140 ml Content used, in which there was a column 1.2 cm in diameter and 10 mm in length, in which 2.8 g Polyst'jrolkücelchen, on the surface of p-aminophenylmercury acetate when AMWS was covalently bound.

The entire amount of liquid in the circulatory system was pumped out of 140 ml pumped once every 4 minutes.

With the help of an oxygen electrode built into the circulatory system, a so-called Clark electrode, the oxygen content was recorded continuously, amplified with an amplifier and recorded on a recorder. Through this It is possible to reduce the metabolic activity of bacteria due to the Track oxygen consumption continuously and directly. As a test liquid was a cellulose-containing mineral solution, as test microorganisms were cellulose. * kteriel used. This system was preferred to a nutrient broth because this itself, too in the absence of living microorganisms, oxygen is consumed and thus an exact There is no basis for determining the oxygen consumption of the microorganisms.

At the beginning of the experiment, the rest of which was carried out at 30.5 0C took place, the oxygen consumption was switched on for 30 minutes with: r circulation pump the pure, bacteria: pure and cellulose-containing mineral solution determined; he proved me as negligible. Thereafter, 20 ml of the nineral solution were drawn off and through 20-ml of new mineral solution replaced in the cellulose bacteria in one concentration of 108 germs /: were included. Then the oxygen consumption set in immediately, the initial oxygen concentration of the solution fell from 95 within about 15 Minutes to 80% and then remained constant, i.e. the oxygen consumption and so the metabolic activity of the bacteria came to a standstill after these 15 minutes After a further 15 minutes, another 20 ml of "used" solution was removed and poured through the same volume of fresh mineral solution with cellulose bacteria the concentration of 108 germs / ml cs.

The consumption of oxygen started immediately, came abt'r n.tc! T 10 b @ s 15 minutes to a halt again. These tests were carried out a total of eight times; there was no evidence of resin that the antimicrobial effect of the in the column located polystyrene beads with superficially bound AMWS only diminished to the slightest extent. Especially about the cellulose bacteria before locculation To make it resistant, the mineral solution was used in the 5th, 6th and 7th attempt before the Inculcation shaken with air. This measure did not affect the Killing after inoculation into the circulatory system with the only exception that the oxygen concentration due to t {t: -s introduced oxygen in the overall system less abfie @.

Through these time-lapse experiments with completely unusual germ counts is clearly underlined that the inventive method under technical Conditions, for example water sterilization, with single and double column filling can be operated for long periods of time, which among other things results in the outstanding economic efficiency of the procedure demonstrated: is.

Claims (1)

Claims: (1) Method for sterilizing a liquid and inspesondene of water or an aqueous solution, thereby @ekennseichnet that the liquid to be sterilized is brought into contact with a solid the surface of which has at least one antimicrobial substance chemically bound is. (2) The method according to claim 1, characterized in that the bond the antimicrobial substance is covalent on the solid surface. (3) Method according to claim 1 or 2, characterized in that the antimicrobial substance is organic silver and / or organic tin Connection is. (4) The method according to claim 1 to 3, characterized in that the Antimicrobial substance on the surface of the solid via a spacer is chemically bound. (5) Method according to claim 1 to 4, characterized in that two or more types of antimicrobial substances on the solid surface chemically bound with different effects or different spectrum of effects are. (6) VerLallrell according to claim 1, dadul-cll, daiJ der Solid from one of the following material groups. the following is selected: (a) natural polymers, (b) synthetic polymers, (c) glass, (d) ceramics, (e) charcoal or active charcoal, (f) synthetic charcoal. (7) Method according to claim 1 and 5, characterized in that the solid has a large surface due to its shape. (8) Method according to claim 1 and 6, characterized in that the solid is in the form of a filter medium. (9) Method according to claim 1, characterized in that the sterilization carried out in one or more contact apparatus (s) connected in series in em or in which, due to the shape of the solids, the largest possible surface, on which the antimicrobial substances are chemically bound, is present. (10) The method according to claim 9, characterized in that in the case several contact devices connected in series. in the direction of flow, at least the last contact part is mechanical Filter is designed to separate entrained germ. (11) Method according to claim 9 or 10, characterized in that in the contact apparatus (s) solids with various antimicrobial agents acting substances can be mixed or arranged in layers. (12) Method according to claim 9 or 10, characterized in that in the case of several contact devices, these are each filled, i.e. solids with different contain antimicrobial substances.