FR2747947A1 - PROCESS FOR THE DISPOSAL OF ANIMAL WASTE - Google Patents

Abstract

Process for eliminating waste obtained from animals (1) comprising the following steps: - cooking animal waste (1) in a first autoclave (2) until masses are obtained which can be sucked by pumping, - pumping of said masses in a second autoclave (3), - sterilization of said masses in the second autoclave (3), - homogenization of said masses in a mixer (4), - mixing of said masses in a mixed collecting tank (7) of so as to obtain an intermediate product, - the routing of said intermediate product in a digester (8), where said intermediate product undergoes biological digestion.

Description

The invention relates to a process for the elimination of organic waste,

  and in particular animal waste, the intermediate product obtained by this process and the use of the intermediate product for the production of biogas. Disposal of animal waste is subject to prescriptions known to the epizootic police. This waste is usually processed into animal meal or

in liquid feeds.

  The corpses at risk are either incinerated or mechanically fragmented, sterilized and then transported in very small quantities to a treatment plant. They are then subjected to a treatment

  biological degradation of organic matter.

  These processes, however, prove to be unprofitable and

  are not feasible for large quantities.

  The main object of the invention is to overcome the above drawbacks by proposing an economical process.

  for the disposal of animal waste.

  Another object of the present invention is to provide a method which meets the requirements of the epizootic police and which allows to safely remove larger volumes of dead animals at risk epizootic. A first subject of the invention relates to a method

  for the disposal of animal waste.

  A second subject of the invention relates to the production of an intermediate product suitable for incorporation in large quantities into organic sludge.

  from conventional treatment plants.

  A third subject of the invention concerns a

  use of the intermediate product.

  A first subject of the invention relates to a method

  disposal of organic waste.

  For this purpose, the process for the disposal of animal waste according to the invention comprises the following steps: - the cooking of the animal waste in a first autoclave until obtaining masses that can be sucked by pumping, - the pumping of said masses in a second autoclave, - the sterilization of said masses in the second autoclave, the homogenization of said masses in a mixer, - the mixing of said masses in a mixed collection tank so as to obtain an intermediate product, - the routing of said intermediate product in a digester, where said intermediate product is subjected to

biological digestion.

  Thus, the invention basically uses a process, called IBO process, also suitable for production

  feed, at certain stages of processing.

  In known processes used for the production of animal feed, the animal waste is reduced before further processing into pieces of cm in an open mill. Since these grinders are not hermetically sealed, there is a risk of contamination of the environment during

  waste treatment with epizootic risk.

  BSE (Bovine Spongiform Encephalitis) prions

  can be disseminated.

  The use of such a method is therefore to be avoided.

  One advantage of the IBO process according to the invention is to make this type of contamination impossible during the course of the

  treatment necessary for the elimination of corpses.

  In the IBO process according to the invention, such grinders are replaced by at least one autoclave where the slaughtering waste is physically decomposed by cooking until a mass that can be sucked by pumping is obtained. This can then be pumped to one or

  several other autoclaves downstream.

  In a subsequent stage of the treatment, the animal raw materials thus ground are sterilized

in an autoclave.

  According to the legal regulations valid in Switzerland, this sterilization takes place at 133 C and 3 105 Pa for 20 minutes. As these conventional autoclaves can withstand a pressure of 8 105 Pa, it is possible to substantially increase their sterilizing power by increasing the pressure from 5 105 Pa to 6 105 Pa and / or

  further extending the duration of exposure.

  The present invention takes particular advantage of the particular advantages of disinfection in a humid environment. When waste has to be transformed into

  animal flour, the material sterilized as described above

  it is defatted, dehydrated and ground.

  In the IBO process according to the invention, on the other hand, it is homogenized from the point of view of structure and fat content in a suitable mixer and is conducted in liquid form towards the next stages of production.

treatment.

  In the process according to the invention, the liquid material, also called intermediate product, obtained by the IBO process is added in a controlled manner to the digesters of conventional treatment plants or

similar fermenters.

  It turns out that the animal sludge to be treated in Switzerland represents only half a percent of the

  total production of sewage sludge.

  The fact that in the digester, the intermediate product of the IBO process according to the invention, applied for the disposal of animal waste generates additional production of biogas, has proved

particularly advantageous.

  Waste with epizootic risk thus makes it possible to obtain as final product not only ash,

  but also energy that can be upgraded as biogas.

  The remaining substance from digestion can still be treated, for example, be definitively

  incinerated in a cement plant for further processing.

  Another object of the invention is the production

an intermediate product.

  The intermediate product according to the invention is characterized in that it has a controlled fat content and a high content of carbon and

lipids.

  Another object of the invention is the use of

  intermediate product for the production of biogas.

  Other objects and advantages of the invention

  will appear in the following description

  with reference to the attached single figure representing a

  diagram of the steps of the method according to the invention.

  According to the method of the present invention, the waste obtained from animals 1, which is in Switzerland of the order of 25,000 tons per year, are cooked in a first autoclave 2 until a mass that can be sucked by pumping. This ensures sufficient grinding, the bone material crushed too coarsely

can not be pumped.

  In a second autoclave 3, the pretreated mass

  as above is sterilized under overpressure.

  This grinding and sterilization can be done in conventional autoclaves and can treat

  the mass under predefined minimum conditions.

  Thus, it is possible for example to set the size of pieces to 5 cm maximum side, the pressure to 3 105 Pa, the temperature to 133 C and the treatment time

at 20 minutes.

  In the case of a raw mass contaminated with ESB prions, a temperature of 150 C in a humid medium or 3000C in a dry medium is considered sufficient for sterilization. The sterilized mass is then conveyed to a mixing device 4 which homogenizes its structure and its

fat content.

  This homogenization proves essential for obtaining an intermediate product that can be eliminated in

wastewater treatment plant.

  In order to be able to control the fat content of an intermediate product that can be removed, the different batches of the homogenized mass are collected first in separate tanks 5, 6, o

  their fat content is measured.

  In a mixed collecting tank 7, the masses from the separate tanks 5, 6 are mixed to produce an intermediate product whose composition corresponds to the

  requirements of digester operators.

  Due to its high carbon and lipid content, this intermediate produces superior production

of biogas in the digester 8.

  The homogenization of the structure and the fat content allows a digestion without fluctuations of

too much temperature.

  The typical production volume for a digester 8 with a capacity of 2700 m3, with a load of 18 m3 of intermediate product and 300 m3 of fresh sludge, is about 5000 m3 of biogas / day in 12 hours. This gas is

picked up in a collector 9.

  The remaining substance undergoes dehydration according to a conventional method in 10, then is incinerated

in 11.

  The use of at least two series-coupled autoclaves makes it possible to obtain a higher sterilization power and to exclude the danger of contamination of the environment during grinding, which has proved

to be a primary benefit.

  Thus, the IBO process according to the invention is a

  economic process for the disposal of animal waste.

  In addition, this IBO process fully meets the requirements of the epizootic police, even for

waste & epizootic risk.

  These can be exploited in particular

  industrially in the production of biogas.

Claims (7)

  1. A method for removing waste obtained from animals (1) comprising the following steps: - the cooking of animal waste (1) in a first autoclave (2) until obtaining masses that can be sucked by pumping, pumping said masses into a second autoclave (3), sterilizing said masses in the second autoclave (3), homogenizing said masses in a mixer (4), - mixing said masses in a mixed collection tank (7) of to obtain an intermediate product, - the routing of said intermediate product in a digester (8), where said intermediate product is subjected to biological digestion.   2. Method according to claim 1, characterized in that batches of homogenized masses with different levels of fat are collected in separate tanks (5, 6) before being conveyed to the tank mixed manifold (7).   3. Method according to claim 2, characterized in that the intermediate product obtained in the mixed collection tank (7) is a mixture of batches of the masses.   homogenized stored in separate tanks (5, 6).   4. Method according to claim 1, characterized in that the waste obtained from animals (1)   come from corpses with epizootic risk.   5. Intermediate product obtained from animal waste (1), characterized in that it has a controlled fat content and a high content of carbon and lipids. Intermediate product according to claim 5, characterized in that it is obtained by the process according to   any of claims 1 to 4.   7. Use for the production of biogas of an intermediate product obtained by the process according to one of   any of claims 1 to 4.