WO1992017072A1

WO1992017072A1 - Process for sterilizing and sanitizing waste and/or valuable substances from recovered animal corpses and its use

Info

Publication number: WO1992017072A1
Application number: PCT/EP1992/000702
Authority: WO
Inventors: Wilfried Rähse; Johann Fues
Original assignee: Cognis Gesellschaft Für Bio- Und Umwelttechnologie Mbh
Priority date: 1991-04-08
Filing date: 1992-03-30
Publication date: 1992-10-15
Also published as: DE4111253A1

Abstract

An improved process for sanitizing and if necessary for at least partially drying waste and/or valuable substances from recovered animal corpses, in particular in connection with the sterilization of valuable substances for the preparation of animal fodder, is characterized by subjecting the material to be sanitized to drying process conditions with superheated water vapour at least for a period sufficient to ensure the required sterilization. This process is suitable for eliminating pathogenic germ infestation and in particular for ensuring the quality of valuable substances or valuable substances-containing residues of animal origin, preferably at least partially dried. It can be used in combination with the recovery of animal fodder additives of vegetable origin by drying and if necessary by disintegration of the corresponding vegetable matter with superheated water vapour.

Description

Process for the decontamination and sanitation of waste and / or valuable materials from animal carcass recycling and its application

The invention relates to a new proposal for decontamination and safe hygienization of waste and / or valuable materials from animal carcass recycling. In particular, the invention seeks to provide a technologically simple and cost-effective option for reliably practically arbitrary quantities of feedstocks of the type concerned here, regardless of the extent and type of their possible contamination, without new problems, for example due to the need for them To create pollutant removal.

The disposal of animal carcasses and carcass waste, in particular the corresponding waste from slaughterhouses, from butchers, from poultry breeding or also of further origin, poses considerable practical problems which can be attributed to a whole series of different causes. Already the .massage of the annual carcass animal waste requires high-tech disposal processes in order to exclude uncontrollable environmental hazards from improperly disposed material. In the area of the European Community alone, waste of the type affected here is produced in the order of several million tons annually.

Carcass waste from healthy animals is a high-quality commodity which, according to the current practice of the carcass utilization institutes, can ultimately be fed back to fattening cattle by recycling via processing into animal meal. The essential prerequisite for this, however, is that the entry and / or transmission of pathogens can be excluded with certainty. Today's practice shows that there are particular difficulties:

Waste materials of animal origin of the species concerned are known to be ideal breeding grounds for pathogenic germs of all kinds, so that even when processing residues from a healthy animal population special safety measures for the hygienization of the goods to be fed again must be provided. However, the actual situation in today's livestock farming is much more complicated. Diseases of all kinds of animals are known side effects of animal rearing, reference being made only to the so-called cattle disease with its pathological change in the brain substance or the corresponding course of the disease in sheep, which is known as scrapie or so-called scrapie. More recently, epidemic-like diseases have appeared in the pig fattening, in particular the offspring of piglets falling victim.

In the field of poultry farming, salmonella infections are found to a high degree today, which can be transmitted to humans and lead to their disease. But animal carcass material of quite another origin has also been recognized as a potential germ carrier. Substantial amounts, especially from overseas countries, deliver fish meal as a raw material for the production of animal feed and process it by the relevant large industry. It has been shown that such fish meal can show considerable contamination, be it that insufficient sterilization has been carried out in the countries of origin, or that uncontrolled wedging has occurred during transport. The practically complete control of all of these possible transmitters for undesired germs in areas of application for recycling, in particular in the area of animal feed, is practically not possible. Accordingly, there are considerable voices today that, for example, generally want to ban the import of carcass flour or consider the feeding of animal meal to be of any concern at all. Taking into account the above-mentioned problem of coping with considerable amounts of these materials based on animal carcasses and further taking into account the high value of this material of animal origin, there is an urgent need to reliably and hygienically and decontaminate such a good of animal origin on a large industrial scale - if necessary, immediately before incorporation into the sterile animal feed - to enable. The teaching of the invention described below creates the possibility for this. The teaching according to the invention aims to ensure that the material to be sanitized is disinfected by exposure to heat, possibly with the help of hydrolytic influences. It is known that in a very large area, potential pathogens, in particular those based on bacteria, are destroyed in a comparatively short period of time even at sterilization temperatures of approximately 100 ° C. If higher temperatures, for example those up to about 120 or 130 ° C., are used, the treatment time of the goods to be hygienized can be substantially reduced and / or more thermostable pathogens are destroyed. Particularly intensive disinfection, for example also with respect to comparatively stable spores, can be achieved with the use of hydrolytic influences. The teaching according to the invention is intended to open up the possibility of using an industrially known and practicable heating method for the disinfection of the material concerned here without the formation of secondary wastes which in turn require further processing.

The core of the teaching according to the invention lies in the combination of the known technology of drying fabrics by the direct action of superheated steam on the material to be dried with the known knowledge of decontamination or hygienization by the action of temperature in the range of at least about 100 ° C.

Accordingly, the invention relates in a first embodiment to a method for hygienizing and, if desired, at least partially drying waste and / or valuable materials from animal carcass recycling, in particular as part of the disinfection of valuable materials for the preparation of animal feed, the new method thereby It is marked that the goods to be hygienized are subjected to the working conditions of drying with superheated steam at least for the period of time sufficient for the required disinfection.

In further embodiments, the invention relates to the use of this method for eliminating pathogenic germs and in particular for quality assurance in the processing of preferably at least partially dried-up valuable residues or residues containing valuable substances of animal origin, the application of the process for the decontamination of carcass flour, in particular for its use in the preparation of animal feed, for the disposal of slaughterhouse or butchery waste and for the disposal of waste materials from poultry farming being in the foreground.

The technology of drying with superheated steam through its direct action on aqueous valuable substance preparations and / or finely divided water-containing solids has been known since the beginning of this century. This is an alternative process technology in which, instead of hot air or mixtures of hot air with hot flue gases, superheated steam is used to introduce the evaporation energy into the material to be dried and to remove the water vapor formed. The first proposals for such a process modification date back to 1908. In the last few decades in particular, the possibility of such drying processes using superheated steam as the hot gas medium has been intensively investigated in the literature and compared with the drying processes based on hot air known in practice. From the extensive relevant literature, reference is made to the following publications, which in turn contain extensive bibliographies in this field: AM Trommelen et al. "Evaporation and Drying of Drops in Superheated Vapors" AIChE Journal 16 (1970) 857-867; Colin Beeby et al. "STEAM DRYING" Soc of Chem Eng, Japan, Tokyo (1984), 51-68 and WA Stein "Calculation of the Evaporation of Liquid from Wet Products in the Spray Tower", Process Engineering 7 (1973) 262-267. The drying process with superheated steam can be carried out in batches , but in particular also be operated continuously, a finely particulate liquid and / or solid feed material in the fluidized bed, in fluidized beds or in the spray tower generally being subjected to countercurrent or cocurrent treatment with the hot steam. Proposals from the more recent patent literature deal in particular with the device-like design of plants which are suitable for the throughput of large quantities of material using this type of process. Reference is made here to EP-Bl 058651 and EP-Bl 153704. The drying processes put into practice using superheated steam as a hot gas stream have hitherto used comparatively uncomplicated wet materials as the material to be dried. The term "uncomplicated materials" is to be understood in two ways, taking into account the task according to the invention: the products previously subjected to this process are unproblematic from the point of view of potential pathogenic germs or contamination, but are also simple in terms of process technology to process. Corresponding technical processes have been developed for drying wet brown coal, sand, for the production of dry animal feed of vegetable origin or for drying paper pulp.

One of the publications already cited brings careful investigations into the extension of this working principle to the drying of wet materials of various origins. AT THE. Trommelen et al. describe in "Evaporation and Drying of Drops in Superheated Vapors" aoO detailed investigations on isolated and a predetermined particle size droplets of various wet materials, on the one hand in their treatment with sweeping hot air, on the other hand with sweeping hot steam. Among other things, the temperature dependence of the drying speed, the characteristic temperature profile in the drop being examined depending on the hot gas flow used and its predetermined temperature, as well as characteristic deviations of the dried material granules to be compared with one another are examined. Pure water, a wide variety of aqueous preparations from the food sector such as aqueous sucrose solution, tomato juice, coffee extract and milk, solutions and suspensions of purely inorganic materials based on a clay suspension and aqueous solutions of sodium sulfate and potassium nitrate are used as the aqueous material to be dried.

When comparing the work with hot air and hot steam on the one hand, an important difference is shown, which is of fundamental importance for the understanding of the present invention: when working with the conventional hot air flow, the drying process begins effectively even at low product temperatures. The water depletion is so pronounced that when reaching the Material temperature of about 100 ° C the drying is almost complete. For example, about 90% of the total water present has already been discharged from the drop at this point. The course of the drop temperature looks completely different when using superheated steam. By condensing the superheated steam on the cooler feed and releasing the heat of condensation to the material to be dried, the aqueous drop is spontaneously heated to the boiling point of the water under working conditions, ie when working under normal pressure to temperatures of about 100 ° C. This boiling temperature is maintained as a minimum temperature in the droplets during the entire drying period. The respective loading of the aqueous phase with the dry substances to be obtained leads - depending on the degree of dryness of the drop - to individual deviations in the temperature profile upwards at an earlier or later point in time.

The studies by Trommelen et al. The laws of aqueous solutions and / or suspensions shown in the course of drying with superheated steam at the material temperature of the aqueous drop also remain valid for a solid material present in the superheated steam stream. The teaching according to the invention makes use of this.

Are the valuable substances of animal origin to be hygienized either in aqueous solution and / or suspension or else from the outset as, for example, granular to fine-particle solids with a natural water content corresponding to the ambient conditions in the superheated steam flow at a temperature which is below the If the condensation or evaporation temperature of the water is below the selected working conditions, then liquid water condenses on the surface of the introduced particles until - by absorbing the heat of condensation - the material temperature of the introduced material contributes to the evaporation point of the water Has reached working pressure. When working in the range of normal pressure, this means the practically spontaneous heating of the introduced particulate material to the minimum temperature of around 100 ° C. At the same time, this involves the condensation of water in the liquid phase on the heating up particulate material. This process does not only take place on the outer surface of the individual Particles instead. If a valuable substance of the type in question, which is already present as a solid, is used in particulate form, the steam penetrates through the always sufficiently porous structure of the solid particle and, on the one hand, leads to penetrating heating to the boiling point of the water under process pressure combined with an equivalent ¬ appropriate moisture penetration with liquid water. The amount of water separated during this heating phase is limited in terms of quantity and can be, for example, in the range from about 10 to 15 or at most 20% by weight of the solid particle concerned in each case. This separation of liquid water in the goods to be hygienized is an important aid in the sense of the task according to the invention. In the subsequent drying phase due to the influence of the superheated steam, the re-discharge of the amount of liquid water entered is only possible if the differential particle area concerned has assumed the evaporation temperature of the water under process conditions. The penetrating heating of the respective material particle in the drying phase is thus reliably ensured. Temperature gradients in the differential range, such as can occur in the cross section of a material particle, for example in the course of drying or heating in a hot air stream, are excluded in the context of the teaching according to the invention. It is obvious that an important determining element lies here for the objective of decontamination according to the invention. The wetting of a primarily particulate to granular material, which appears to be dry, with limited amounts of liquid and the subsequent drying of such a material in the superheated steam stream ensures that all material areas consistently reach at least the predetermined boiling temperature of the water under the process pressure. This is the prerequisite for reliable disinfection in the sense of the objective according to the invention.

The last-described aspect is specifically reinforced in a preferred embodiment of the invention. In this embodiment, a preferably particulate material from animal recycling, which is dry per se, for example corresponding fish meal, is admixed with restricted amounts of water and preferably mixed intimately before being introduced into the zone of superheated steam. That way 9 Ensure that even under comparatively extreme working conditions of the temperature of the superheated steam used in the drying zone, the penetrating wetting of a material to be disinfected - for example also in the form of granules - is ensured. As is known, the speed of the drying process in the superheated steam flow increases as the temperature of the steam used increases, so that at steam temperatures of the feed steam above 200 to 250 ° C. or even above 300 ° C., a comparatively rapid drying also and especially of the primarily condensed water portion takes place. Water components previously entered can ensure the setting of the temperature level required according to the invention in each area of the particulate material.

The teaching of the invention thus encompasses the use of the animal origin to be sterilized in admixture with virtually any amount of water. Purely aqueous solutions of valuable substances or suspensions such as blood, blood plasma and the like can be subjected to the process as well as solid materials which appear to be practically dry and can be stored in a stable manner. Specifically, the water content entered with the material to be treated and the process conditions of the treatment according to the invention then determine whether predominantly to almost exclusively hygienization is carried out by destroying germs or whether the drying aspect also plays a substantial role. Dried materials which are sterile dry products with predeterminable residual water contents are generally obtained as the process product. The sterile condition of this good can be ensured in a manner known per se until further processing or until consumption. It is obvious that, for example, previously unknown possibilities become accessible to the feed manufacturer in this form: the setting of a predetermined and / or prescribed minimum protein content, for example in fattening feed mixtures, becomes at least largely independent of the quality of a material supplied from the carcass disposal . The reliable disinfection of this component of the mixture, for example immediately before it is mixed into the multi-component fattening feed, is made possible reliably by the comparatively simple hygiene step in the sense of the inventive action. 3

In this context, another preferred embodiment of the teaching according to the invention can be understood:

In addition to the protein suppliers of the type described so far, important components of the mixture of feed mixtures are nutrients and fiber of plant origin. The digestion and drying process using superheated steam has been proposed several times for their large-scale extraction as particulate fines from vegetable raw materials. Reference is made to the EP-B1 058651 and 153 704 mentioned at the outset. Both documents and further material of the state of the art cited therein deal with the drying of vegetable particles in the fluidized bed in a continuous process using superheated water steam as drying gas. In the particular embodiment of the teaching according to the invention discussed here, such work methods of the prior art are made on the basis of simultaneous decontamination and intensive mixing with protein suppliers on the basis of waste and / or valuable substances from animal carcass recycling. Thus, in the sense of this embodiment of the teaching according to the invention, the vegetable material to be dried in admixture with the animal carcass recycling material to be disinfected according to the invention can be introduced into the drying stage with superheated steam and at the same time hygienically sterilized there with the drying of the vegetable mixture components. It is obvious that this can be an important simplification for the production of feed mixtures.

Details on the teaching according to the invention

The following information applies to the specific process conditions under which, according to the invention, the material to be disinfected is exposed to the superheated steam in liquid, at least pasty, flowable and / or in solid particulate form.

In a preferred embodiment, the material to be sanitized is heated to temperatures in the range from about 100 to 180 ° C. and preferably to temperatures in the range from about 100 to for a sufficient period of time l *

150 ° C set. The setting of these material temperatures in the process is determined on the one hand by the aroma pressure of the treatment with superheated steam, but on the other hand also by the residence time and / or the specific form of the procedure, as can be seen from the following considerations. While in the initial phase of the treatment in particular the respectively selected process pressure is responsible for the boiling point of the water and thus the primary temperature of the material, the temperature of the superheated used in subsequent phases of the material treatment, in which at least extensive drying has taken place Water vapor and / or the residence time of the goods in the water vapor atmosphere can be decisive. In this context, a known effect affects whether the process is carried out in countercurrent or cocurrent.

It is preferable to work with inlet temperatures of the superheated steam in the decontamination stage which is at least about 35 ° C. and in particular at least about 50 ° C. above the boiling point of the water at the given working pressure. Preferred temperature ranges for the steam inlet temperatures are between about 150 and 450 ° C and can in particular be in the range of about 180 to 350 ° C. A number of considerations are included in the determination of the specifically selected inlet temperature of the steam, of which the following should be mentioned by way of example: the water content of the goods to be sanitized and thus the required extent of their drying, the process and result-related residence time of the goods in the water vapor atmosphere, the temperature sensitivity of the material to be disinfected and / or the contamination to be destroyed. In this context, it should be pointed out that the treatment according to the invention can be associated with denaturing or cooking or at least a gelling of the protein-containing valuable substances of animal origin. However, the value of the treated material as an animal feed component is usually not adversely affected. Of importance for the choice of the respective water vapor temperature can also be the above-mentioned dwell time of the goods in the influence of the temperature stress by setting either the conditions of the co-current method or by treatment in counter-current. Is the nature of those present in the feed Germ characteristics and their sensitivity to thermal influence known, of course, determines the type of germ load to be removed with the process conditions.

The selected working pressures can be predominantly or exclusively in the range of normal pressure, but it is also possible to work at least in sections at elevated pressures, which can then be, for example, in the range up to about 15-25 bar, preferably in the range up to about 5 bar .

The residence time of the material to be disinfected under the influence of the superheated steam is determined on the one hand by the extent and the type of microbial load and on the other hand by the process conditions chosen, it is usually in the range of at least about 1 minute, but can also be comparatively long in special cases Reach periods of approximately 20 to 30 minutes, for example. In general, treatment periods of less than 10 minutes are sufficient for the feed material to be sufficiently hygienized. The thermal treatment also for a period of a few hours, e.g. 1 to 5 hours is not excluded.

To carry out work with superheated steam, reference is made to the extensive printed literature cited at the beginning. As described in detail there, work is preferably carried out in a closed circulation system of the superheated steam, into which the material to be disinfected is introduced and the cleaned material is discharged. Any excess amounts of water vapor that may result from additional crop drying are removed from the closed steam flow, and the process conditions required in the sanitation stage are maintained by supplying sufficient energy to the steam cycle. Conventional separation stages such as filters, cyclone separators and the like can be provided in the steam circuit. The material discharged from the process can, if required, be subjected to a short final drying if necessary. example

500 g of fish meal of unknown origin infected with Salmonella germs are treated in a reaction zone through which superheated steam flows under the following process conditions:

Water vapor with an inlet temperature of 180 to 190 ° C flows through a vapor-permeable base plate at normal pressure into an externally thermally insulated room into which the fish meal feed material moistened with 50 to 100 g and well mixed is added. The speed of the steam addition is limited in such a way that there is no substantial discharge of the solid material from the treatment zone. After a dwell time of 5 minutes under process conditions, hot air and then cold air are first led into the drying room instead of the hot steam. The dried state of the treated fish meal is comparable to the feed before it is moistened. The treated goods are exempt from Salmonella contamination.

Claims

Patent claims

1. Process for the hygiene and, if desired, at least partial drying of waste and / or valuable materials from animal carcass recycling, in particular as part of the disinfection of valuable materials for the preparation of animal feed, characterized in that the goods to be hygienized are subjected to the working conditions of a dry ¬ tion with superheated steam at least for the period sufficient for the required disinfection.

2. The method according to claim 1, characterized in that the material to be disinfected is exposed to the superheated steam at normal pressure or elevated pressure in liquid, but preferably in at least pasty, flowable and / or solid particulate form.

3. Process according to Claims 1 and 2, characterized in that the preferably fine particulate material is kept at product temperatures in the range from approximately 100 to 180 ° C, preferably in the range from approximately 100 to 150 ° C, at least for the period sufficient for disinfection and the desired extent of drying of the material is preferably determined by the choice of temperature and the amount and / or duration of action of the superheated steam supplied.

4. Process according to Claims 1 to 3, characterized in that one works with inlet temperatures of the superheated steam which lie at least about 35 ° C, preferably at least about 50 ° C above the boiling point of the water at the given working pressure, preferably with Steam inlet temperatures in the range of 150 to 450 ° C, preferably in the range of about 180 to 350 ° C.

5. Process according to Claims 1 to 4, characterized in that one works in the range of normal pressure or elevated pressures which preferably do not exceed 15 to 20 bar and in particular approximately 4 to 5 bar. l

6. Process according to Claims 1 to 5, characterized in that one works with fluid beds or fluidized beds which are preferably operated in continuous throughput, in which the material to be disinfected is treated with the superheated steam in countercurrent or in cocurrent.

7. The method according to claims 1 to 6, characterized in that the treatment of the goods to be sanitized takes place in a closed circulation system of the superheated steam, from which only the water vapor quantities which may be due to additional crop drying are removed.

8. The method according to claims 1 to 7, characterized in that the material to be hygienized is mixed with water before being introduced into the zone of superheated steam and is at least penetratingly moistened.

9. Application of the method according to claims 1 to 8 for eliminating pathogenic germs and in particular for quality assurance in the processing of preferably at least partially dried valuable substances or residues of animal origin containing valuable substances.

10. Embodiment according to claim 9, characterized in that the method according to claims 1 to 6 for the disinfection of carcass flour, in particular for its use in the preparation of Tierfutter¬ means for the disposal of slaughterhouse or butchery waste and / or for the hygiene of waste materials from poultry farming.

11. Use of the method according to claims 1 to 8 in combination with the production of feed additives of plant origin by drying and optionally digestion of corresponding plant material by means of superheated steam, the feed materials of plant and animal origin being exposed to the superheated steam at least temporarily together.