DE2812193A1 - PROCESS FOR THE PROCESSING OF SEWAGE SLUDGE INTO USABLE PRODUCTS - Google Patents

Description

DR BERG D! PL.-! M G. STAPF

D1PL.-IN3. SC'r'V -. 'Arr Γ-. Cf. Γ /., "J AIR ^

Germany

Attorney File 28,975 March 20, 1978

Process for the treatment of sewage sludge can be used

Products

The invention relates to a method for processing from sewage sludge to usable products, the products obtained according to the process and their use.

DT-OS 25 20 528 describes a method for isolating and drying solids from suspensions, which is characterized in that one suspensions with a liquid or a mixture of liquids, which the new solids contained in the suspension wets or partially dissolves and becomes insoluble or only insoluble with the suspension liquid has limited solubility, added in such a way that a liquid multiphase system is formed and the genius of a 'Durchini Subjects until agglomerates of the solids form, separates them from the liquid multiphase system and, if necessary dries.

In the further processing of this subject it has now been found that when this method is applied to sewage sludge it is possible not only to isolate and granulate the solids contained in sewage sludge, but also in usable products to be transferred.

This is due to the fact that by choosing suitable liquids an extraction of e.g. pollutants and odorous substances from the Sewage sludge takes place. Such an extractive purification of

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Sewage sludge connected to an agglomeration to expand Granular sludge solids, their isolation and use are not yet known.

The invention thus relates to a novel processing method for clear sludge and is characterized by the fact that nan Sewage sludge with at least one liquid and 'if necessary further additives are added, the multiphase system is mixed, the solid granules that form from the liquid phase separates and dries, with the condition that as a liquid a water-absorbing solvent or system is used in the event that the solids content in the sludge is between 0.1 and 35% by weight, or in the event that the solids content In the sludge there is also more than 35% by weight as a liquid water-insoluble solvent or system without a drainage function is used.

Under sewage sludge here is that in the settling basins (clarifiers) of the sewage treatment plants when cleaning domestic and industrial sewage to understand residual sludge. A distinction is made between:

a) fresh sludge; contains the sediment and floating matter of the wastewater in their natural state (e.g. faeces, paper, vegetable scraps); this fresh sludge falls after separation of the coarse screenings and the sediments of the sand trap in the sedimentation basin at; it is hygienically dangerous because of the presence of pathogenic germs, spores and worm eggs.

b) activated sludge; a sediment from the sedimentation basin after the biological purification stage. It's almost fresh odor-free and consists largely of microorganisms and residues of non-degradable or difficult-to-degradable substances, so that it is bacteriologically and parasitologically questionable.

c) digested sludge; a product from the anaerobic fermentation of fresh and / or activated sludge.

These sludges have roughly the following composition:

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Fresh sludge Activated sludge Digested sludge Fats and oils 7-35 5-12 3 - 17 Pentosans 1 2 1.5 Hemicellulose 3-5 1.6 Cellulose 4-6 0.6 lignin 6-8 8.4 Proteins 22-28 16-21 Unknown substances approx 10 k approx. 7 approx. 11 ash 20 - 40 40-55 35-40 13-17 25-35

Sewage sludge in the broader sense also includes sludges of a general nature, which are also produced according to the invention Process can be processed. Sludges from special processes and / or their wastewater, for example, come into consideration from communal areas, e.g. slaughterhouses, from food / Industrial companies such as dairies, compressed yeast and starch factories, fermentation processes (penicillin / stryptomycin plants, mycelium waste culture media) , then breweries and others; also from agricultural operations (e.g. processing of animal faeces see below feed).

The solids content in sewage sludge is between 0.1 and 99 percent by weight, especially between 2 to 95 percent by weight, with both the liquid sludge in the sewage sludge Sedimentation basin as well as the dried sludge is to be understood. Both hydrophilic, above all, are used as the sludge liquid Water, as well as hydrophobic liquids. The amount of liquid in the sludge is between 99.9 to 1 percent by weight, especially between 5 and 98 percent by weight.

The method according to the invention allows both individual slurries as well as mixtures of these sludges.

As a liquid, which is the sewage sludge with a solid content of 0.1 to 35 wt .-% is added, such comes

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into consideration, those with the mud fluid partially to completely is miscible, and removes so much water from the sludge that the residual water remaining in the sludge is sufficient to make the sludge to granulate. However, if the residual moisture in the sludge is just enough to granulate the solid contained in it, which is especially the case with slurries whose strength content is greater than 35% by weight, a liquid can also do this which is immiscible with water can be used.

Examples of hydrophobic liquids that are not miscible with water are: halogenated hydrocarbons, such as above all Perchlorethylene, then 1,2-dichloroethane, chloroform or trichlorotrifluoroethane, also hydrocarbons, such as hexane and also special boiling point gasoline, e.g. petroleum ether.

■, As hydrophilic, wholly or partially miscible with water and liquids suitable for the process according to the invention are mentioned, for example: alcohols such as methanol, ethanol, propanol such as isopropanol and butanol, such as n-butanol, sec-butanol and isobutanol, then ketones such as acetone or cyclohexanone and esters such as methyl or ethyl acetate.

However, it is also possible according to the invention to use mixtures of solvents, the liquid mixture consists of water-insoluble or partially water-soluble solvents and totally water-miscible solvents. For example, the following mixtures are involved: butanol. especially isobutanol and methanol, 1,2-dichloroethylene / isopropanol or isopropanol / ethylene chloride.

The preferred solvent which is completely or partially miscible with water is an alcohol such as methanol, ethanol or propanol or butanol used or. a mixture of butanol, especially isobutanol and methanol and not used with water Miscible solvent a halogenated hydrocarbon such as especially perchlorethylene.

The process according to the invention can also be used further additives can be added. For example, in Question: Solvent-soluble complexing agents that serve to separate traces of metal, especially traces of heavy metals; then products for fertilization or soil improvement, such as

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Urea-formaldehyde resins or commercially available inorganic and organic fertilizers.

The method according to the invention consists in adding a suitable defined liquid to the sewage sludge if necessary with further additives and the whole thing is mixed at a temperature of approx. 15-2OO ° C, preferably room temperature for about 1-60 minutes. The solvent systems mentioned form with the water-containing sewage sludge is a multiphase mixture of at least one liquid phase and one solid phase, which Form build-up granules with stirring. The water has the function of preferably wetting the solid sludge Bridging fluid. This bridging fluid must so that the Granulation can be carried out in a controlled manner, be present in a suitably small concentration. Sewage sludge with Dry matter contents of about 0.1 to about 35 percent by weight must therefore before or during the granulation either by a partially and / or totally water-soluble solvent or by Azeotropic distillation with water-insoluble solvents and / or by mechanical and thermal dehydration methods be treated.

During the granulation process, i.e. during the treatment of the sewage sludge with solvents, especially with hydrophilic ones Solvents, the biological cells that are in the clar- '■ mud are present, blown open, and thereby e.g. the natural fats and oils, fat-soluble vitamins, difficult to break down Hydrocarbons, odor from protein putrefaction and other lipid bodies as well as water extracted. At the same time, the solid sludge swells, with the volume during the subsequent Maintain separation and drying and the pore structure is solidified by intragranular solid bridges.

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After mixing and granulation, the granulated Separated sludge solids, for example by decanting, filtration, centrifugation and similar mechanical separation processes; this is followed by direct and / or indirect thermal drying.

After drying, the protein-containing biomass is cleaned, enriched, digested and thus in a for soil biology suggests an easily usable form.

The process according to the invention gives a Sludge solid dry granulate with a grain size of approx 0.1 mm to 4.0 mm, which has the following specific properties: ·

- granulated, expanded, solidified form;

- Storage stable at temperatures from -25 ° C to + 50 ⁰ C and relative humidity up to 95%;

- good free-flowing;

- odorless;

- freed from pollutants;

- internal surface enlargement by approx. 50 to 150 times due to swelling of the sludge solids (BET surface areas up to 35 m ² / g);

- pore structure;

- pronounced absorbency (e.g. 200-3007 », based on its own weight, hydrophilic liquids), which creates a certain retention force and a correspondingly dosed release in dry soil is given;

- good and quick availability of nutrients (high protein content and favorable protein composition);

- bacteriologically and parasitologically harmless;

- Bulk weight 0.5 to 0.15 kg / 1.

Thanks to the fact that the inventive method above all through the extraction of the pollutants, if necessary through the removal of hot metals, an incomparably purer one Product than the well-known thermal treatment process of · sewage sludge supplies and in a simple manner their

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If it enables use, it is superior to the known methods.

Thanks to the specific properties mentioned, the sewage sludge solid granulate can be used economically. These "sludge solid granules ¹¹ can be used, for example, as fertilizers, effective soil improvers, if suitably tolerated as animal feed, impregnable animal feed additive, and as carrier material for active substances, eg as carrier material for high-quality feed additives.

In addition to the solid granules, a lipid body extract falls that can be subjected to further recycling and / or processing.

By using such granulates in soil biology there is, for example, an increase in the dry matter content (increase in growth) of plants.

The following examples illustrate the invention without limiting it thereto. Temperatures are in degrees Celsius indicated. The inner surface is according to the BET method measured (S. Brunauer, P.H. Emmet and E. Teller, J.Am. Chem. Soc, VoI'.60 (1958), p. 309-319). The surface of the Granulate is compared with the average

Surface of the solid in the sludge with about 0.2 m / g (measured on the thermally dried solid - 2 hours at 120 ° C - from the mud).

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example 1

In a 5 liter beaker, 2200 g make one Isobutanol / methanol mixture (10: 1) 600 g of activated sludge (aqueous) with 4.17o dry matter within one minute Stir with a glass stirrer at approx. 400 rpm, at room temperature added. "Granules are formed. After 5 minutes, the granules are filtered through a Separated from the filtrate on a suction filter. The moist granulate residue is dried in a vacuum drying cabinet up to Left constant weight. A gray, odorless granulate with a particle size distribution of <0.1 to Ξ> 0.8 mm.

The granules obtained have a specific surface area of 25 m / g (BET) and a SchUr.tgev.'icht of approx. 0.25 kg / l and can be used as fertilizer, soil improver, carrier material or animal feed additive.

The isobutanol / methanol mixture is used instead of the 2200 g 3000 g of n-butanol or 3000 g of isobutanol are obtained with the otherwise identical procedure equally good properties.

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BeisDiel 2

1.5 kg of a communal activated sludge (aqueous) with .a dry matter content of approx. 13.57 «with 0.8 kg ! an isobutanol / methanol mixture (10: 1) mixed at room temperature and then through a Fryma homogenizer Type MZ-5O / R pumped. The homogeneous mass is stirring in a 10 liter beaker at approx. 400 rpm, weighing 4.5 kg of the above-mentioned solvent mixture and stirred for 30 minutes. After that, a carriage and a Cloth filter filtered. The granulate residue obtained contains approx. 20% water. This is then dried in a fluidized bed, air or vacuum dryer, 179 g of one being added receives odor-free dry granulate.

The porous granulate obtained has a particle size distribution of 0.1 to approx. 1.5 mm. The inner surface is 21 m ² / g.

The sludge solid granulate obtained can according to the Details of Example 1 are used.

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Example 3

1.5 kg of a communal activated sludge (aqueous) with 13.5% dry substance was according to the information in the example granulated. The separated granules were initially over Air-dried overnight on trays, then in a vacuum drying cabinet held at 60 ° to constant weight. Granules (pore structure) with a particle size distribution are obtained from about <0.1 to about 2.5 mm.

Examples 4 to 8

200 g municipal activated sludge (aqueous) with a dry substance content of 13.5% were with different amounts of an isobutanol / methanol mixture according to Example .2. granulated and dried in a vacuum drying cabinet. The granulate properties are a function of the amount of solvent can be seen from the following table. The columns mean: Column 1: Different amounts of solvent mixture:

Isobutanol / methanol (10: 1) in parts by weight based on 1 part of dry substance.

Column 2: water content (%) of the moist granulate. K ~ 7.onne 3: Extracted lipid body fraction in% of the used Dry matter after concentration.

2
Column 4: surface area in m / g of the granulate.

Column 5: weight in kg / 1.

Column 6: Average granulate size in mm.

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TABEL

example 1 2 3 4th 5 6th 4th 18.5 59 9.1 5.8 0.42 1-4 5 20.4 37 9.8 30.4 0.22 0.5-1.6 6th 22.2 23 10.3 31.2 0.22 0.2-1.2 7th 29.6 14.8 13.2 36.7 0.16 0.2-1.2 8th 37.0 9.6 13.4 37.0 0.16 0.2-0.8

The dried granules have a residual moisture content of less than 5% water. The extract residue according to column 3 contains for the most part natural and mineral fats and oils.

Example 9

1200 g municipal activated sludge (aqueous) with 17-18% dry matter content were with 480 g of an isobutanol / methanol mixture (10: 1) mixed at room temperature, homogenized and pressed through a Fryma mill. The homogeneous mass becomes 960 g the same solvent equipment while stirring at 500 rpm, given. After 1 minute, 960 g of solvent mixture are added, and after a stirring time of 6 minutes, another 1200 g of solvent mixture are added admitted. The gradual addition of solvent results in granules with little dust. After about 20 minutes it will filtered using a suction filter and then divided the granules. One half is in the vacuum drying cabinet and the other half dried in a fluidized bed dryer. The two Types of drying do not provide different granulates. A total of 162 g of dry granules are obtained. The grain distribution of the granulate obtained is between <0.1 to approx. 1.5 mm. The surface of the granulate is

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- ^ 27 m / g. The granules obtained have a solid pore structure and are used as fertilizers, soil improvers, carrier materials or animal feed additives.

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Example 10

780 g of municipal activated sludge (aqueous) with 17% dry matter content are together with 80 g of a urea-formaldehyde resin and 960 g of a mixture of isobutanol / methanol ^ homogenized using a Fryma mill. After that, under Stirring in the beaker, 220 ml of water were added dropwise over the course of 30 minutes, large granules being obtained with stirring. For drying, a further 1920 g of an isobutanol / methanol mixture (~ 10: l) are added and the mixture is stirred for another 20 minutes, the solid products sucked off and over. Night in Vacuum drying cabinet dried at 60 °. About 180 g are obtained Granules with a particle size distribution of <.. 0.1 mm ^ is 4.0 mm.

The surface is 24.8 m / g. The granules have a solidified pore structure and cause in greenhouse experiments after addition to maize crops an increase in growth based on the maize dry matter from 30 to 90% compared to untreated maize and compared to blind tests with urea-formaldehyde resin.

Example 11

350 g of a mixture of fresh sludge and municipal activated sludge (approx. 1: 1). (watery) with approx. totally 307 ″, dry substance are mixed together with 210 g of isobutanol / methanol (10: 1) using a Fryma mill at room temperature and homogenized Then 188 g of solvent mixture saturated with water are poured into the beaker while stirring, with the fine Granules can now be built up to larger granules within 5 to 15 minutes (stirring intensity approx. 800 rpm). " To dry the moist granules are now at 300 rpm. 333 g of solvent mixture were added and the mixture was stirred for about 3 minutes. The granules are separated off by means of a Nutsche. The granules obtained are first dried in a fluidized bed and then in a vacuum drying cabinet. Dark, hard granules which are resistant to abrasion are obtained.

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The grain size of the granules obtained is between

«<· 0.1 mm to 4.0 mm. The surface is 14.0 m / g.

The granules have a porous structure and can be used as described in Example 1 will. If you use instead of 210 g of the isobutanol / methanol mixture 400 g of cyclohexanone and instead of the As a solvent mixture, also cyclohexanone, then with the otherwise identical procedure, granulates are obtained that are more equal Quality.

Example 12

12 kg of a mixture of fresh and activated sludge (aqueous) ⁰ ^ - * - 30% dry matter content, 7.2 kg of a solvent mixture isobutanol / methanol (10: 1) are homogenized in a Fryraa mill at room temperature. The homogenized mass is placed in a 100 liter glass vessel and 8.4 kg of solvent mixture saturated with water are added with stirring. The build-up of granules is complete after 20 minutes and a further 19.2 kg of solvent mixture are added for drying. After five minutes it is sucked off. The granulate is dried in a fluidized bed dryer. The granules obtained (residual moisture 4.8%) are a little softer than in Example 11 because more solvent was used. The other data correspond to example 11.

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Example 13

68.9 g Mirchsc.ilamm (approx. 477 »dry matter content), (aqueous) consisting of 50 g of a mixed sludge from fresh / activated sludge and 18.9 g of thermally dried activated sludge Homogenized with 225 g of perchlorethylene using a Polytron stirrer at room temperature. Small granules are formed in the process. The mixture is then stirred in the beaker at 600 rpm for 15 minutes, during which the granules begin to build up. Then be the granules sucked off. The drying takes place in the fluidized bed and then in the vacuum drying cabinet. Granules with a grain size distribution are obtained. <0.1 mm up to 4.0 mm. The average surface of the granules is 2.9 m / g. The granules have a porous structure on and have a good shelf life. They are used as fertilizers, soil improvers, carrier material or Animal feed additive. If you use an equal amount of hexane or 1,2-dichloromethane or instead of 225 g of perchlorethylene Petroleum ether or trichlorotrifluoroethane with otherwise the same Working method, you get granules of equal quality.

Example 14

1.5 kg of mycelium with 357, dry matter content are in one

Suspended mixture of 2 kg of isobutanol and 340 g of methanol.

Then, while adding 475 g of water, granules are built up over the course of 25 minutes and with vigorous stirring. Granulation is brought to an end by adding a further 2 kg of isobutanol. The mixture is slowly stirred for a further 15 minutes and then filtered. After the granules have been dried in the fluidized bed, 420 g of dry granules are present. These wise a grain size of <0.1 now up to 3 mm. The granules obtained have a porous structure and find use as animal feed.

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Claims (11)

Claims 1. A process for the granulation of sewage sludge into usable products, characterized in that sewage sludge is mixed with at least one liquid and optionally further additives, the multiphase system is mixed, the solid granules formed are separated from the liquid phase and dried, with the condition that A water-absorbing solvent or system is used as the liquid in the event that the solids content in the sludge is between 0.1 and 35 percent by weight, or in the event that the solids content in the sludge is over 35 percent by weight, a water-insoluble solvent or as the liquid system is used without a drainage function. * 2. The method according to claim 1, characterized in that the water-absorbing solvent is one from the class Alcohols, ketones and / or esters is used. 3. The method according to claim 1, characterized in that the water-insoluble solvent is one from the class Halocarbons and / or hydrocarbons is used. 4. The method according to claim 2, characterized in that is used as alcohols, methanol, ethanol, propanol or butanol. 5. The method according to claim 4, characterized in that the alcohol is a mixture of butanol, especially isobutanol and Methanol is used. 6. The method according to claim 3, characterized in that perchlorethylene is used as the halogenated hydrocarbon. 80984 0/0812 ·· «· ·· IMI It ·· Il ι ··· ι · · t · a ··· I · · III ■ 11 ·· »· ·« t · f · 7. The method gemMss claim 1, characterized in that it is carried out at a temperature of 15 ° to 200 ⁰ C. 8. The method according to claim 7, characterized in that it is carried out at room temperature. 9. The method according to claims 1 to 8, characterized in that that as additional additives, complexing agents, products used for fertilization and soil improvement. 10. The obtained according to the method of claims 1 to 9 Granules. 11. Use of the according to the method of claims 1 to 9 obtained granules as soil improvers, fertilizers, animal feed or as carrier material. 809840/0812