LARSEN STEINAR (NO)
LOKOEEN JON (NO)
LARSEN STEINAR (NO)
LOKOEEN JON (NO)
| WO1995021129A1 | 1995-08-10 |
| NO125229B | 1972-08-07 | |||
| CH281347A | 1952-03-15 | |||
| DE2224363A1 | 1973-11-29 | |||
| US3722378A | 1973-03-27 |
| 1. | Process for the treatment of consumption waste, where the waste is subjected if necessary in advance to source sorting, for example by removing glass, metals, wood and other separable material, whereby a residual waste is produced, characterised in that the residual waste is treated by a combination of the following steps: a) that the residual waste is divided up in one or several steps to a suitable particle size to form a finely divided residual waste, b) that the residual waste is subjected to a treat¬ ment at a suitable pressure and temperature to form a sub¬ stantially hermetised or conserved residual waste, c) that the finely divided mass is treated with an impregnating agent which makes the mass wholly or par¬ tially water repelling, d) the residual waste is subjected to an infra red irradiation, and is mixed if necessary with a binding agent, after which it is utilised as insulation material or is formed into an insulation block or plate (40) . |
| 2. | Process in accordance with claim 1, characterised in that during step b) the residual waste is treated at a temperature in the range of 160 180°C, the pressure being maintained at 5 15 kg. /cm.2 and especially at about 10 kg. /cm.2 to form a hermetised, finely divided residual waste, the hermetised, finely divided residual waste being subjected to a drying process for removing possible water after which it is added to bacteriakilling and conserving means. |
| 3. | Process in accordance with claim 1, characterised in that during step c) water glass is used as impregnating agent . |
| 4. | Process in accordance with claim 1 and 3, characterised in that during step c) the finely divided mass is impregnated with a water glass solution comprising P T/NO97/0012 16 calcium or sodium silicate dissolved in water to a concentration of 30 weight %. |
| 5. | Process in accordance with claim 1 and 5, characterised in that the waste material is mixed with a binding agent in a mixing ratio corresponding to up to 95 weight % waste material where the residue is binding agent . |
| 6. | Process in accordance with claim 1, characterised in that during step d) styropore or styropore granules (EPS) are utilised as binding agent, and the mixing ratio between waste powder mass and styropor binding agent is 90:10. |
| 7. | Process in accordance with one of the preceding claims, characterised in that during pressure die casting of the mass into a block/plate in the casting mould in step d) the mass is subjected to steam at a temperature of 140 180°C, preferably 170°C and at a pressure in the range of 7 13 kg/cm2, and preferably of 10 kg/cm2. |
| 8. | Process in accordance with claim 1, characterised in that during step d) the treatment is carried out with infra red rays to a temperature of about 150°C to obtain sufficient compressive strength. |
| 9. | Plate or blockshaped insulation product, characterised in that it comprises finely divided waste material, especially from household waste, where the finely divided material is conserved, made water repelling, and subjected to a treatment which layers to¬ gether the particles. |
| 10. | Product in accordance with claim 9, characterised in that it is fabricated as indicated in one of the claims 1 8. |
| 11. | Use of the product in accordance with claims 7 9 as an insulation block designed for building and/or construction purposes, and especially in the case of road purposes. |
The present invention relates to a process for the treatment of consumption waste such as is indicated in the introduction to the following claim 1.
The invention also relates to a plate- or block- shaped insulation product as is evident from the introduc¬ tion to claim 9, together with a utilisation of the pro- duct as according to claim 11.
Waste from private consumption and industry has hitherto either been placed in open or closed deposits or burned in incinerators. Open waste deposits involve how¬ ever growing environmental problems in the form of bother- some smells and the drainage of percolating water plus that the deposits (which nobody will have m their environmental proximity) have gradually assumed signifi¬ cant volumes and demand thereby large spaces. In an open waste deposit the problem is m addition amplified by percolating water as a consequence of the waste being irrigated with rainwater.
In more recent times society has become, as a result of the afore-mentioned problems, more and more interested m screening the source of the waste before putting it m deposits, possibly food waste being biologically decom ¬ posed in a composting installation. The screening of
source involves divorcing glass, paper, metals and organic waste from the amount of waste and is treated separately. There is also increasing interest in the reuse of materials which become discarded. To-day it is usual to compost food residues and organic waste, while glass and metals can be employed anew, possibly remelted. Also paper waste can be recycled to a large degree and made into cardboard and packaging.
The present invention has especially to do with that residual waste which remains after the source screening is undertaken. However such residual waste will also contain smaller amounts of the afore-mentioned materials, that is to say glass, metal, wood and food waste.
These residual amounts of consumption waste which will form a part of the process according to the invention will include the following materials:
Dissimilar types of plastic such as PVC, poly¬ ethylene, polystyrene and polyurethane.
All types of paper, pasteboard and cardboard. Minor amounts of food waste of all types.
Textiles, skins and leather.
Paper napkins.
Wood.
Minor amounts of soap, cosmetics and washing powder. Minor amounts of metals which are not sorted out earlier.
Minor amounts of glass and ceramic material which have not been screened out earlier.
Minor amounts of rubber. Minor amounts of garden waste such as grass and leaves .
Minor amounts of paint, varnish and glue substances.
Building waste, tar paper, mineral wool, plaster and the like. Minor amounts of tobacco and ash.
Minor amounts of substances which are normally sent for special waste handling.
Residual material which is normally found in extremely small amounts relative to the total quantity of waste.
It is thus a residual waste of a mixture of one or more of these listed materials which it is desirable to handle by the present invention.
A proportion, and especially the food residues, in such a mass of waste will be able to form conditions for the growth of microorganisms. Such organisms can live at -12°C (psychrophilic) , at 110°C (thermophilic) , in distilled water (Caulobacter) , in brine (halophilic) and individual organisms like Deinococcus survive powerful electromagnetic radiation. All organisms are however dependent on free water in order to grow. In order to avoid microbial growth in food, wood etc. a series of conservation and sterilisation techniques have been developed. One of these methods is autoclaving and drying. There are two known and environmentally friendly techniques which, when they fulfill certain minimum demands, will keep the product sterile over longer periods. It is desirable by the invention to produce the safest process with the idea of killing (sterilising) microorganisms in the waste.
AUTOCLAVING
The most usual and safe way of achieving sterility is to use superheated steam. If sufficient heat is added (usually 15 minutes at 121°C) all forms of life will be destroyed. The time it takes to sterilise depends upon a series of factors: a: The number of organisms in the waste for auto ¬ claving.
The reduction in the number of organisms by sterilisa¬ tion is measured in decimal reduction time (D) . Decimal reduction time (D) is defined by the expression
D = T/log (N 0 /N τ ) where D is the inactivating rate (the time it takes to
reduce the number of cells by 90% at a given temperature, T is the time, N 0 is the number of cells before heating and N τ is the number of cells after heating. That is to say that D is dependent upon the temperature and the number of cells before autoclaving.
Example: Bacillus subtilus has D 121 = 0.5 min.
The time it takes then to reduce 10 8 spores/ml to 0.1 spores/ml will be then 4.5 minutes.
The decimal reduction time is consequently an expression of the time it takes to reduce the number of organisms of a type having a ten power. The decimal reduc¬ tion time is dependent upon the organism, medium and tem¬ perature as will be clearly evident from the following Table 1.
b: Heat resistance to an organism.
Besides hyperthermophilic bacteria, negative cells will be killed by ten minutes at 80°C, while spores from yeast and fungus require 20 minutes at 80°C and bacteria spores require 15 minutes at 121°C. These times must be viewed as the least required since virus and bacteria spores are present which survive this.
c : The contact between steam and waste . By autoclaving the heat energy is transferred with the water vapour to the organism and one gets denaturing of proteins which so leads to death. In porous, compact or hydrophobic material the penetration of steam is reduced and the autoclaving cycle must be extended, in order that one shall be sure that the whole material achieves the autoclaving temperature. This is important since higher temperatures are required in order to kill an organism with dry air.
Table 1 Some spore-forming bacteria and their decimal reduction times in water or phosphate buffer (pH 7)
Organism D - value in minutes
B. subtilus 3 D 90 4 . 8
B. subtilus D 121 = 0 . 5
B. subtilus var.niger J 9i
B. stearothermophilus D 121 = 2 . 1
C. Butulinuπf Duo = 1 - 2 C. perfringens D 90 = 4 . 5 - 12 0 b C. perfringens D 101 = 1 . 4 - 5 . 2
a: B. = Bacillus, C = Clostridium, b: dissimilar strains of C. perfringens
d: The temperature in the autoclave
With increased temperature the sterilisation will go more rapidly and the time in the autoclave is reduced. Usually an increase in the temperature of 10°C will reduce the decimal reduction time (D) by a factor of 10.
e : The conditions in the waste after autoclaving.
A short heat shock will often activate spores to sporulate. If the conditions after autoclaving are good, with respect to growth, one will be able to get growth of bacteria. It is therefore desirable to dry the waste directly after autoclaving. This will remove water and prevent possible growth of surviving bacteria.
Table 2 Minimum water activity for growth of some microorganisms and the water activity in saturated sucrose solution and salt solution.
Organism Minimum a w value
B. subtιlus a 0.90
C. botulmuπf 0.93 S. aureus a 0.86 Yeast < 0.85
A. nιger b 0.84
X. bιsporus b 0.61
Saturated sucrose solution 0.85
Saturated NaCI solution 0.75
a: bacteria, B = Bacillus, C = Clostridium,
S = Staphylococcus, b: mushroom (fungus) , A = Aspergillus,
X = Xeromyces
Drying
Drying or lowering the water activity is another much used technique for conserving food and wood materials. The water activity is defined like this: The moisture in a substance can be stated as the water activity.
The water activity <a w ) is given as: where p is the vapour pressure for water for the medium and p 0 is the vapour pressure for pure water at the same temperature. Drying will not kill microorganisms, but prevents them from growing. Relatively few microorganisms can live in dry environments (a w < 0.85) and microorganisms are not reported which can live at lower water activit i es than 0.61. In dry environments filamentous organisms, like fungus, have a greater advantage than single cell orga ¬ n i sms, in that they can grow between microbes microniches having a higher water content. Sufficient drying of the
waste will thus prevent microbial growth of the most heat- resistant bacteria, since all these are monocellular (1) . By sufficient autoclaving one can get growth of xerophilous organisms (which live in dry environments) . These will form water so that other organisms can live. "OMBRUK AS" have chosen to dry the autoclaved waste at 188°C. On dry sterilising it is considered that 30 minutes at 180°C is enough to kill all types of spores.
Further conservation of the waste can occur by adding salt, chemicals or by changing the pH to an acid or basic environment. By arranging the waste inside a water-tight plastic bag the waste will be hermetised and inaccessible to microbial decomposition. Casting the waste in PVC, PE and PS - plastic will form a barrier against the ingress of water, plus the waste will be little exposed to exter¬ nal microbial decomposition.
It is an object of the present invention to produce a novel process by treatment of residual waste for the manu ¬ facture of an insulation product, which product will have a practical application without it having negative environ ¬ mental consequences .
In the present invention it is also an obiect to be able to remove the need for open and closed deposits for the placement of residual waste. A consequence of this is that by eliminating the need for a deposit problems like percolating water and odour will also be totally eliminated.
It is further an obiect of the invention to remove the need for burning waste, which will further involve eliminating air contaminants as a result of exhaust gases from the incineration installation, plus the need for depositing ash residues from such incineration installations.
It is an additional object with the present invention to produce sterile conditions in the mass of waste.
The process according to the present invention is distinguished by the features which are evident from the characterising portion of the following claim 1.
Further preferred forms of the process according to the invention are evident from the dependent patent claims 2 - 8.
By the process according to the invention all gaseous and vapourous discharges are by requirement cleansed at every stage before they are released into nature. The insulation product according to the invention is distinguished by the features which are evident from claims 9 and 10.
According to the invention the waste material is in¬ corporated in a plate material with insulation properties adapted for building and/or plant purposes. Such an insula¬ tion block is especially suited for utilisation during the construction of roads.
By the present invention there is consequently pro¬ duced a process for the treatment of waste together with the application of an insulation product made thereby which involves that all produced waste can be reused. This means that it will no longer be necessary to deposit and/or incinerate residual waste which remains after source screening. By the present invention all daily con- sumption waste from a region can for example be converted to an adequate industrial product even during the course of the day the waste is delivered to the production site. This means that the total day's production of consumption waste can be taken m hand immediately, so that the large problems of odour and percolating water which are attached to the waste deposits currently used, are completely eliminated.
The invention consequently involves bringing the consumption waste through an industrial process with the subsequent compression to a finished block- or plate- shaped insulation product. There is thus produced a completely competitive insulation plate. Furthermore a
residual waste of the afore-mentioned kind can include residues of such an insulation plate, for example 25 years after it has been manufactured the first time.
The present invention shall now be explained in more detail having regard to the accompanying drawings, where Fig. 1 shows schematically the stepwise treatment of the waste forward to the finished product . Figure 2 shows a preferred application of the insulation product according to the present invention. As is evident from Fig. 1 the process according to the invention can be divided into 12 steps. Step 1 During this step the waste is collected from the consumer or industry, the waste being a residual waste after an introductory source sorting by the consumer. This means that glass, metals, wood and individual plastic sub¬ stances are already separated and delivered to a suitable receiver. The residual waste is transported, in a form which is defined earlier, in a tight container without being affected by possible rainy weather. The container is brought to the receiver station in the next step.
Step 2 - Sorting. At this station an additional sorting of the waste is undertaken in order to remove the most significant of the possible glass-, metal-, wood- and plastic - parts which have not necessarily been removed earlier. The mass of waste is also conducted through a grinding machine for grinding up the waste so as to manage a simpler sorting.
Step 3 - Demoisturing, grinding up and mixing. After the sorting the waste is conducted to a station where the waste is subjected to a compressing pressure in a piston press so as to be demoistured by pressing out water. Preferably the piston press operates at a pressure of 25 kg/cm 2 during demoisturing. By this step a minimum 75% of the moisture is taken out of the waste.
Ste p 4 - Hermetisation/Conservation. In this step the waste is hermetised and conserved by treatment with steam at a temperature in the range of 140 - 225°C, especially 160 - 180°C (as mentioned previously during Autoclaving, point a, about 120°C, for 15 minutes can however be sufficient) , the pressure being maintained at 5 - 15 kg/cm 2 and especially at about 10 kg. /cm 2 . The steam is supplied from a high pressure steam boiler. The treatment can besides be carried out as is evident during the earlier passage of the autoclaving process. Exhaust gases and waste water (condensed water) are treated as is stated in step 3.
Step 5 - Drying. In the drying zone the mass is converted to the insulation material. The drying is carried out in a spiral drying drum at a high temperature and for a sufficient period in the range 140 - 190°C, and especially at 140 - 180°C, and preferably at about 160°C for about 10 minutes. The drying is carried out until the material has a suffi ¬ ciently low water activity, preferably as is defined earlier under point DRYING. In case of need bacteria killing and concerning means can be added to the material, which now has a dry approximately chip-like form. In this step there can also be supplied ground up building waste, such as building plates and other wood in order adjust the content of the waste.
Step 6 - Treatment with fungus killers and the like.
The mass of waste is now sterilised and is mixed with fungus-killing means and expansion means. The mass contains about 80% moisture and has a minced meat-like consistency.
Step 7 - Pelleting. The mass is subjected to pelleting in order to condense/compress and mould the mass to a desired shape and density.
Step 8 - Drying with infra red radiation. In order to obtain sufficient compressive strength in the manufactured pellets, the mass is subjected to infra red radiation up to 150°C. By this treatment with infra red rays there occurs both a drying, and the particles are layered, puttied or sintered together to larger flakes something which viewed totally gives said effect and increasing compressive strength.
Step 9 - Grinding up.
The part dried mass is ground down in a grinding apparatus to a desired granule size, preferably 1 - 3 mm.
Step 10 - Impregnation with water glass. The powdered mass of waste is impregnated and coated with an agent which makes the mass of powder to the smallest possible degree attracted to water, that is to say it becomes approximately water-repelling. Water glass, more specifically sodium or calcium silicate (Na 2 Si0 3 or K 2 Si0 3 ) is such an impregnating agent. When these silicates are dissolved in water, a viscous fluid is formed. Water glass is employed to impregnating wood and paper materials in order to make these fire inhibiting.
In order to carry out the impregnation the powdered mass is led down into a treatment container where there is preprepared a bath of water glass having a Na 2 Si0 3 concentration of 35 weight %.
Step 11 - Drying. After submerging in the water glass solution, the impregnated mass is dried in a drying chamber at 140 - 180°C to a water activity of 0.6.
Step 12 - Finished product. The powdered mass having the necessary water- repelling and inert properties, now functions as an insulation material. The mass from step 11 is mixed with a binding agent, and the mixture is pressed into the form of a block (indicated by reference number 40 in Figure 2) in a casting mould having a mould well suited for whatever purpose. Material having styropore or styropore granules (EPS) in a mixing ratio corresponding to 90 weight % waste-powder material and 10 weight % styropore. The mixture is so filled/poured into the casting mould in the usual manner and is subjected to the influence of steam at a temperature of 140 - 180°C, preferably 170°C and is compressed at a pressure in the range of 7 - 13 kg/cm 2 , and preferably at 10 kg/cm 2 . By the heat and steam pressure treatment (the moulding) the styropore is hardened and expanded as a result of the styropore beads containing dissolved volatile petroleum ether (pentane) which is released by the treatment with hot steam. In this way the volume of a block can increase by about 50°%. Styropore 42 of the insulation block 40 will be very light, and have a density down towards 0.02 g/cm 3 , and it has very good insulation capability.
The finished insulation plate 40, which is wholly harmless to the environment, can be transferred to storage.
As is evident from Figure 1, three parallel production lines A,B,C are arranged for processing the inert and water repelling waste powder to blocks/plates. All possible exhaust gases and waste water from the previous steps can be treated as is indicated before.
The finished insulation plate consequently comprises mixed in waste material process treated in the form of chipped waste, wherein impregnating means and bacteria- killing and conserving means possibly being added.
By the present invention a product is obtained having the following properties:
- Satisfactory insulation capability.
- Satisfactory compressive strength.
- Long life span
- Favourable price relative to competitive products because of a receiver price for consumption waste of about 550 Norwegian kroner per ton, and because of a large number of produced plates/ blocks.
- Standard weight per plate about 12 kg., and according to need. - Standard size 800 x 800 x 400 mm and according to need.
- Harmless to the environment .
An insulation plate according to the invention can be divided up, such as by sawing, to any size and shape what¬ ever, and is well-suited for construction purposes, and especially in the construction of roads, railway lines, and airports.
Figure 2 shows such an application of the product according to the present invention. The Figure illustrates a cross-section through a road fill. After excavating/filling in order to form the basis for the roadway there is laid a water-permeable fabric 50. Upon this fabric 50 is placed a layer of insulation plates 40 where the plates are chained together in a manner known per se (for example according to the groove/tongue prin¬ ciple) . On the shoulder of the road to the left in the Figure the insulation plates can be arranged according to the invention on top of one another in a partially step- shaped design. On top of this layer of insulation plate is laid another fabric layer 52 after which a layer 54 of gravel material is laid on top of the layer of fabric. The gravel material is compacted in a well-known manner and the roadway is covered with asphalt or another suitable surface covering 56. In a known manner the layer of insulation plate according to the invention will contri¬ bute to preventing the underlying basis for the roadway
from freezing over, and problems with frost heave and the like.
CONCLUSION According to the invention the waste ought to be exposed to water vapour 150 - 225°C (autoclaving) and thereafter is dried at 140 - 180°C (dry sterilising) . Preferably autoclaving ought to be carried out in ten minutes at 160°C. Further drying ought to be carried out to a water activity of 0.6. Thereafter the material ought to be irradiated with infra red rays to a temperature of about 150°C. On the assumption that the autoclaving, the drying and the irradiating of the waste fulfills these requirements, extra conservation efforts can be omitted. Besides it can be unnecessary to mix in binding agents for the manufacture of the moulded product . Assuming that the manufactured product will be further handled in a dry condition it will have long durability.
With the present invention there is consequently produced a process, a product and an application of a product manufactured thereby, which to a substantial degree will contribute to eliminating the waste problems of society.