AT393668B - Multilayer porous body - Google Patents

Abstract

A multilayer porous body consisting of at least one support layer and at least one active layer which has a smaller pore size than the support layer and has absorption capacity, at least the active layer consisting of chemically inactive inorganic granular substances, preferably silicate-based, for example basalt grains, zeolite grains, Al2O3 grains and binder(s). In this case, at least on the surface of the grains forming the active layer a hydrophobic binder of silicone resin and/or epoxy resin based on bisphenol A is provided, the silicone resin being a resin made up of siloxane units of functionality 1...4 and/or a branched phenylmethyl- polysiloxane and/or phenylmethylpolysiloxane polyester and/or H2O2-polymerized phenyl-methylvinyl-siloxane resin prepared by condensing monomers of functionality 1...3, and the epoxy resin is a bisphenol A-based synthetic resin prepared from 4,4'-dihydroxydiphenylpropane and epichlorohydrin.

Description

AT 393 668 B

The invention relates to a multilayer porous body consisting of at least one carrier layer and at least one », a smaller pore size than the carrier layer on the facing active layer, at least the active layer of chemically inactive, inorganic granular substances - preferably based on silicate, e.g. . B. from basalt, zeolite, A ^ Og Kömchen and binder (s) These porous bodies, which serve in particular as a filter, are for separating liquid and solid substances, for example. For filtering waste water and waste water sludge or for dispersing Gases or liquids are provided.

The construction according to the invention is equally suitable for separating solid and liquid phases and for dispersing gases in liquids or liquids in other liquids or gases and can be used with advantage in the field of wastewater treatment or in general water treatment.

In the course of water purification, filtering operations are carried out, among other things. The organic substances are biodegraded; in some cases, the aggressive gases are expelled from the liquids or gases are fed into them, and dewater (dehydration) of waste water sludge continues. With the help of the invention, these tasks can be accomplished. In one part of the trap, liquid containing solid phase is fed onto the filter structure, which screens out the solid phase. In the other part of the case, a gas is supplied in the form of fine bubbles through the body of the liquid in the course of the dispersion

Different methods are known for solving the filtration and (sludge) dewatering tasks, e.g. B. sand filtering; filtering through stane filter plates; Filtration carried out by glued gravel filters or textile or metal sieves, as well as mechanical filtration (centrifugal and vacuum filtration, sludge pressing, etc.). The classic method of sludge dewatering is drying out.

The efficiency of the known mechanical filtering and dewatering methods is favorable, but their use in filter technology is relatively narrow, and their use in dewatering technologies is limited by their specifically high investment and operating costs.

For this reason, filtration technologies based on the use of natural substances are predominantly used in wastewater treatment, of which sand filtration is the most widespread

In sand filters, the material size increases in the direction of the liquid flow. The solid phase is deposited in the sand layer from the wastewater flowing through the sand filter. It follows that the filter layer becomes blocked and can only be made operational again by removing the filtered solid phase by countercurrent rinsing or by removing the blocked layers and replacing them with new ones.

From US Pat. Nos. 4,452,698 and 4,381,998 rigid filter constructions consisting of multilayer filter plates can be seen. These filter constructions made of granular material by gluing consist of a carrier layer and a filter layer. The carrier layer itself is of course also permeable to liquids, but its pores are larger than the pores of the filter plates. The granules consist of inorganic substances, z. B. A ^ Og, corundum, silicon carbide, boron carbide and the like

Manufacture of filters used. These filters have a relatively expensive construction.

U.S. Patent No. 4,382,863 relates to a similar construction but contains three layers and is also expensive to manufacture. What is common to the constructions according to the three US patents mentioned is that there is a silicone composition whose hydrophobic properties are unsatisfactory.

DE-OS 30 21377 does not describe a hydrophobic surface filter, but an adsorption granulate which on the one hand has a high adsorption capacity for odorous substances, water etc. and on the other hand is a loose, non-sticky mass even when saturated with water. The binder used is based on a silicate or sulfate base. This granulate is primarily intended for use in small animal cages

DE-OS 31 32 369 also discloses an adsorption filter with a gas supply and a gas outlet line and with a desorption device.

U.S. Patent 4,554,261 relates to the extraction of solutes in liquids, but not to the separation of solid and liquid phases.

According to the published Hungarian patent application 216/83 to reduce the groundwater pressure, for. B. for the drainage of cellars, a homogeneous structure (single-layer) glued gravel filter used.

Drying out the sludge is one of the most problematic stages in wastewater treatment. The sludge drying plants require a large amount of space and their mode of operation is largely dependent on the climatic conditions, so that the drainage of the sludge takes a considerable amount of time and the removal of the dry sludge requires - due to the need for appropriate protection of the drainage system - manual work. The further use of the manually extracted sludge is prevented by its gravel content

In the course of the (waste) water treatment, gas-liquid systems appear, on the one hand when the gases in the liquid are removed with the help of other gases fed into the liquid, and on the other hand during biological cleaning in the course of the use of gases. An example of the -2-

AT 393 668 B the first-mentioned application is the expulsion of the aggressive CO2 gas by blowing in air, in the latter case the dispersing of air or oxygen into the liquid mass to ensure the living conditions of the microorganisms in the liquid phase. Of the technologies used to accomplish this task, the deep blowing of air by means of nozzles can be considered the most effective, but the fact that the problem means that the uniform supply of gas cannot be guaranteed. A further difficulty is caused by the fact that a discontinuous gas supply is usually required and that the solid phase in the liquid can cause the nozzles to become clogged during breaks in operation.

The object of the invention is to provide a porous body as a filter and / or dispersion construction, which carries out the filtration with maximum effectiveness, the operation of which requires only a minimal cost and energy expenditure, which is insensitive to clogging, and which is capable of Introduce gas evenly distributed into the liquid.

The invention is based on the knowledge that, if the filter heads are combined with a hydrophobic adhesive to form a filter layer, the adhesive skin covering the granules located there on the surface of the filter construction in the course of the filtering process has an electrical charge with the solid bodies in the material to be filtered receives the same sign electrical charge, whereby it repels the material particles in the material to be filtered. In this way, an effective force field can arise in the area of the surface of the feed granule layer containing the hydrophobic adhesive coating, which prevents the granules in the material to be filtered from adhering to the surface of the filter construction. Instead, a natural filter cake develops from these granules above the filter construction, which is not in direct contact with the filter construction. As a result, cleaning the filter only requires surface rinsing, since solid-state contamination cannot penetrate the interior of the filter and clog its pores.

The basis of the invention is also the knowledge that the synthetic resin coating on the surface also prevents solids and / or microorganisms from settling on the surface in contact with the liquid in the course of biological cleaning or after the ventilation used to expel the harmful gases and clog the pores that function like a nozzle. In this way, a more effective biological cleaning or gas injection is possible.

The object is achieved with a multilayer porous structure of the type mentioned, in which, according to the invention, a hydrophobic binder made of silicone resin and / or epoxy resin based on bisphenol-A is provided, at least on the surface of the granules forming the active layer, the silicone resin being a resin composed of siloxane units with functionality 1 ... 4 and / or a phenyl-methyl-polysiloxane and / or phenyl-methylpolysiloxane-polyester and / or with a branched structure produced by the condensation of monomers with functionality 1 ... 3 H202 polymerized

Phenyl-methyl-vinyl-siloxane resin, and the hydrophobic binder is epoxy resin, which is a bisphenol A-based synthetic resin made from 4,4'-dihydroxy-diphenyl-propane and epichlorohydrin, the molecular weight of which is 380-3800 , Epoxy equivalent 175-4000, ester equivalent 80-200, has a 4-17 OH functional group, its molecular viscosity 5-150 P (at 20 ° C) and its specific weight is 1.14-1.2.

It is hereinafter referred to as " generally " upper and a " in general " lower layer, since the filter construction can not only be installed in a horizontal position (e.g. for gravitational filtration), but can also be arranged in a vertical position.

The formula of the above resin is CH2-CH-CH2 - (- aR-0-CH2-CH-CH2-0-R-) n-0-CH2-CH-CH2 \ / I \ /

O OH O

The porous body is expediently formed such that the thickness of the active layer / layers is 5 to 15 mm, that of the support layer / layers 50 to 150 mm. While the arrangement on the surface of the porous body in contact with liquid to build up a more effective force field of relatively small pores, it seems advantageous to reduce the filter resistance in the opposite direction and so to provide larger pores on the side opposite the surface in contact with the liquid, even a, conveniently perforated, steel plate or other metal structure, possibly a plastic construction, e.g. B. an aluminum or plastic grid, can take the role of the carrier.

The hydrophobic resin and the electrical force field that is produced also sticks the filter granules together, thus ensuring a constant pore size.

According to the above statements, according to a further feature of the invention, the active -3-

AT 393 668 B

Granules forming layer / layers have a grain size of 0.2 to 1 mm and the pores of the layer / layers have a size of 0.1 to 1 mm.

It is also advantageous if, as has already been pointed out above, the carrier layer of the porous body according to the invention is formed by perforated steel plate (s) or a layer consisting of inorganic granules and binding agent, in which the size of the granules is between 1 to 5 mm and the Pore size is between 0.8 and 1.2 mm

The porous gravel can also be built up from more than two layers, e.g. B. so that the two upper layers of inorganic filter beads and binders, the lower, however, of a perforated steel plate or other perforated plate made of metal or plastic, z. B. an aluminum or plastic grid. However, the filter construction can also be designed in such a way that it contains reinforcement, advantageously steel inserts, which increases the mechanical strength of the support layer.

Both the surface of the active layer and / or the carrier layer can have a cylindrical, conical or hemispherical shape.

In the case of a filtration carried out with the porous body according to the invention, a stronger solid phase (for example sludge) is formed in the course of the latter on the surface of the active layer, which functions as a filter surface, but does not adhere to it. For this reason, the sludge can be removed mechanically and the filter can be regenerated by rinsing its surface.

However, the multilayer porous body according to the invention is not only suitable for filtering, but also for dispersing gases in liquids. In this case, the desired gas is supplied from the carrier layer and the previous filter surface will function as an active dispersant. In this case it is particularly expedient to give this surface a geometry that deviates from the plane. By the fine pores of the active surface, a fine distribution of the injected gas can be ensured, moreover, the binder on the liquid-side surface, which has hydrophobic properties, prevents z. B. in the case of discontinuous operation, the microorganisms z. B. colonize phyto and monoplankton oiganisms (such as algae) and clog the pores. In this way, the construction is permanently operational.

The invention is described in more detail below with the aid of examples:

example 1

To filter municipal sewage sludge, the porous body according to the invention is calculated as follows over an area of 1 mm ^: active filter layer - material (aluminum oxide Al2O3) - grain structure

Size (FEPA standard) Quantity (kg) 22 10.4 36 0.60 70 0.60 Binder: Epoxy resin adhesive (TIPOXIHS) 1.22 kg Layer thickness: 5 mm

Permeability coefficient of the active filter plate K = 2.1.10 '^ cm / s; Void content n = 32%

Backing layer - material: pearl gravel - grain size: 3 to 7 mm - binder: epoxy resin adhesive (TIPOXIHS) 2.25 kg - thickness: 45 mm - mass: 90.0 kg

The filter plates are made in steel stencils, the surfaces of which are carefully cleaned and covered with plastic film. There are three main steps in manufacturing, namely -4-

AT 393 668 B a) .Making the carrier layer (thickness e.g. 45 mm) b) Making the filter layer (thickness e.g. 5 mm) c) Removing the filter body, cleaning the stencils.

In step a), classified gravel and resin are mixed in an exact ratio in a concrete mixer and the mixture is introduced into the stencils in the desired strength, optionally with the addition of reinforcements and with compaction.

To produce the filter layer after step b), the individual fractions of the batch are first mixed dry in a concrete mixer and then the corresponding amount of resin is added. The mixture is applied to the carrier layer produced according to step a) and evenly distributed. The surface is smoothed with a glass plate, which is carefully cleaned of dry resin.

In step c) the filter body, for. B. by tapping out, removed from the stencils no earlier than 24 hours after steps a) and b) to give the resin time to cure. The removed filter body can e.g. B. stacked with corrugated cardboard.

Although convenient, the backing layer need not necessarily be made using a hydrophobic binder.

The initial dry matter content of the municipal sewage sludge was 2.0% (its moisture content was 98.0%). A 4% solution of the preparation " Zetag 57 " used The dry matter content of the dewatered sludge was 38%. A pure, particulate-free filtrate was obtained. FEPA is an international standard for grain sizes, which corresponds to the Hungarian standard MSZ 6506-84

The one component of the epoxy resin adhesive " TIPOX IHS " is a bisphenol-alpha-diglyzidyl ether epoxy resin modified with a reactive diluent, the other component is an aliphatic polyamine mixture (Manufacture " Tiszamenti Vegyimüvek "Tiszaszederkdny, Hungary). The preparation " Zetag 57 " is a polyelectrolyte based on polyacrylamide, a product of Allied Colloid GmbH, Hamburg, FRG.

Command 2

Waste water sludge from a leather factory was filtered with the porous body according to the invention, which was compiled for an area of 1 as follows: active filter layer - material: silicon carbide (SiC) - grain structure

Size (FEPA standard) Quantity (kg) 22 10.40 36 0.60 70 0.60 - Binder: silicone resin adhesive (VP2261) 1.35 kg - Thickness: 5 mm

The active filter plate was heat-treated at a temperature of 150 ° C for 3 hours. The permeability coefficient and void volume were the same as in Example 1; Base layer: same as that described in Example 1.

The initial dry content of the sewage sludge of the leather factory was 1.5% (the moisture content accordingly 98.5%). In this case as well, a 4% solution of the preparation " Zetag 57 " used. The chromium content of the waste water was 100 mg / liter. As a result of the filtration, a dewatered sludge with a dry content of 30% and a suspended matter-free filtrate with a chromium content of 0.05 mg / liter were obtained.

The silicone resin sealer " VP 2261 " is a product of " Wacker Chemie " Munich, Germany and is a bisphenol A-based synthetic resin. -5-

Claims (6)

AT 393 668 B Example 3 Oil-containing sewage sludge was filtered using the porous body described in Example 1. The initial dry matter content of the sludge was 2%, its moisture content was 98%, and a 4% solution of the preparation " Zetag 57 " used. As a result of the filtering, a dewatered sludge with a dry content of 33% and a filtrate water were obtained, the quality of which allowed a feed into the general sewage network. In the case of all three examples, only a rinsing of the surface was required to regenerate the surface of the active layer of the filter plate. The filter resistance in the individual layers did not change in any way even after a long period of operation; flushing (backwashing) was not necessary. Example 4 Using the porous bodies described above, air was dispersed in water using the construction carried out according to Example 2. In the case of a construction with a surface of 1 ts? The air flow was 20 m ^ / h, the amount of oxygen 100 g / C ^ / h, the gross energy consumption 0.6 kw / 1000 g O ^, the average bubble size d = 2.5 mm. Example 5 A porous body was produced according to Example 1, with the difference that in order to form the active filter layer as a binder in this case in epoxy resin modified with 4% silicone and 10% pentaerythritol tetraglycide ester in an amount of 1.2 kg / m ^ used. The pressure resistance of the body or filter produced in this way is 8.8 ± 2 N / mm, its bending strength 3.1 ± 0.5 N / mm ^, and its permeability coefficient 5.4.10 '^ cm / s. With a load as in Example 1, the permeability coefficient, due to the increased hydrophobicity, only reached the value that the filter according to Example 1 showed after 8 months of operation after 18 months. Example 6 A porous body was produced according to Example 1, but this time an epoxy resin modified with 4% Λ silicone and 10% pentaerythritol tetraglycide ester was used in a quantity of 1.05 kg / m, to which an addition of 3% was used. Alcohol added to the winch. Λ The pressure resistance of the body or filter manufactured in this way is 9.3 + 2 N / mm, its flexural strength is 3.1 ± 0.5 N / mm, and its permeability coefficient is 2.1.10 cm / s. For the filter used in the manner described in Example 1 for the treatment of municipal sewage sludge, the permeability coefficient after only 3 years of operation was only 3.2.10 "cm / s, accordingly the service life of this filter is at least 3 years. The greatest advantage of the invention is that no rinsing is required to regenerate the construction, only rinsing of its surface is occasionally necessary, the expenditure of energy, time and labor being insignificant. The construction of the construction is simple, its applicability extremely versatile. The invention is of course in no way limited to the examples described in detail above, but can be implemented in many ways within the scope of protection defined by the claims. PATENT CLAIMS 1. Multilayer porous body, consisting of at least one carrier layer and at least one, smaller pore size than the carrier layer having active layer with adsorption capacity, wherein at least the active layer of chemically inactive, inorganic granular substances - preferably based on silicate - z . B. from basalt, zeolite, Al203 granules and binder (s), characterized, -6- AT 393 668 B that at least on the surface of the granules forming the active layer, a hydrophobic binder made of silicone resin and / or epoxy resin is provided on a bisphenol A basis, the silicone resin being a resin composed of siloxane units representing functionality 1 ... .4 and / or a phenylmethyl- which has a branched structure and is produced by the condensation of monomers having functionality 1 ... .4. polysiloxane and / or phenyl-methyl-polysiloxane-polyester and / or phenyl-methyl-vinyl-siloxane resin polymerized with H202, and the epoxy resin is a synthetic resin made from 4,4'-dihydroxy-diphenyl-propane and epichlorohydrin Bisphenol-A * is a base whose molecular weight is 380 to 3800, epoxy equivalent 175 to 4000, ester equivalent 80 to 200, has a 4 to 17 OH functional group, its viscosity 5 to 150 P (at 20 ° C) and its specific s Weight is 1.14 to 1.2. Body according to claim 1, characterized in that the grains forming the active layer / layers have a grain size of 0.2 to 1 mm and the pores of the layer / layers have a size of 0. Have 1 to 1 mm. 3. Body according to claim 1 or 2, characterized in that the carrier layer is formed by perforated steel plate (s) or a layer consisting of inorganic granules and binder, in which the size of the granules between 1 to 5 mm and the pore size between 0 , 8 and 1.2 mm 4. Body according to one of claims 1 to 3, characterized in that the thickness of the active layer / layers 5 to 15 mm, that of the carrier layer / carrier layers, however, is 50 to 150 mm 5. Body according to one of claims 1 to 4, characterized in that it contains a reinforcement which increases the mechanical strength of the carrier layer, advantageously steel inserts 6. Body according to one of claims 1 to 5, characterized in that the surface of the active layer and / or the Tiägerschicht has a cylindrical, conical or hemispherical shape -7-