GB2265614A - Decomposition of organic waste material - Google Patents

Description

2265614 - I- DECOMPOSITION OF ORGANIC WASTE MATERIAL This invention

relates to the decomposition of organic waste material, and especially for the production of organic fertiliser from a source of organic material, which will include animal material, animal-derived waste material, and plant material including particularly plant material which is a waste by-product to a primary crop material.

The invention is concerned with microbial and thermal degradation or decomposition which occurs when a heap of organic material is caused or allowed to decompose over a period of time under appropriate conditions of heat, moisture content without induction of air. The decomposition which takes place in a properly controlled "compost heap" is a typical example of the type of reaction with which the invention is concerned.

However, the invention goes beyond the decomposition of waste plant material, such as garden type refuse e.g. grass cuttings, leaves and stalks, and by a novel use of suitable additional material(s), enables other types of organic waste material to be decomposed into a useful organic fertiliser material.

The invention enables animal waste materials to be decomposed to form a useful end product, as well as plant waste materials, and including materials such as animal manures e.g. turkey or chicken manures, sewage sludge derived from human waste, and also, surprisingly effectively, waste animal materials such as animal offals not normally found to be suitable for human consumption.

The invention is based on the surprising discovery that waste coffee bean residue (so-called "dregs" obtained after roasting and grinding the coffee beans, and then removing soluble extract to form "instant" coffee powder), of the type derived as a waste product during the manufacture of roasted, ground coffee e.g. in the manufacture of so-called "instant coffee", can be mixed with different types of organic waste material to form a decomposing "heap", and which promotes a decomposing reaction which, over a period of time, results in formation of organic material broken down to a form suitable for use as an organic fertiliser.

The exact nature of the chain of reactions which are set in motion is not clear, neither is it presently clear what part of the coffee bean residue is responsible for the favourable decomposing action which is set in train.

However, it is believed that the favourable decomposing action may be initiated by the presence of tannin in the residue, or by the presence of activated carbon in the residue, provided that a suitable level of moisture is present and also the pH within the heap remains within a certain range.

Accordingly, the invention is not to be considered as being restricted solely to use of coffee bean residue to promote the require decomposition of organic material, but will include use of other suitable tannincontaining materials, such as tea leaf residues, and also other activated carbon residue.

The invention therefore provides a method for the production of organic fertiliser from a bulk source of organic material, comprising mixing a tannin-containing reaction promotion material, andjor'an activated carbon residue with the bulk material to form a heap of the mixed material, preferably applying a coating or covering layer over the heap and allowing &t least part of the heap of mixed material to undergo aerobic decomposition for c sufficient period until this part has broken down or decomposed to an extent to render this part suitable for use as an organic fertiliser.

Conveniently, this part is then mixed with a further supply of organic material to form a further heap which will then undergo accelerated decomposition.

Examples of organic waste material which may be used in the formation of the heap include chicken and turkey manure, which may be mixed with straw if required, as well as sewage sludge derived from human waste, and animal offals of a type not suitable for human consumption.

Waste plant material also may be used in the formation of the heap, including materials such as hops after use in a brewery for making beer.

other materials may be mixed together in the initial formation of the "heap", and accelerated breakdown of this material in the heap is achieved, and which has been shown in experiments to continue for extended periods. The coating or covering layer shields the outer surface of the heap, which becomes hard and cracked so as to resemble somewhat a thatched roof over a period of time; and it appears that this protects the heap from heavy rainfall, and also reduces the generation of wind blow dust which can be a problem in small heaps. Beneath the "skin", there was found in experimental tests with some materials a thin anaerobic laybr about 8 to 10 cm thick, but beneath this the bulk of the heap was found to be almost entirely aerobic.

Examples of the production of organic fertiliser from different sources of organic material, after decomposing over suitable periods of time in heaps will now be described in detail.

Uncovered heaps have been formed about 5 to 7 meters high and about 4 to 5 meters wide, having fast breakdown rates of.between 1 to 3 weeks, and the resulting compost had a very fine texture and looked very similar to John Innes type "compost".

The source organic material used comprised chicken and turkey manure, mixed with straw, and then mixed together with coffee bean residue derived as a waste product from an instant coffee factory of Nestle or other manuacturers of "instant coffee".

A tannin-containing reaction promotion material may be formed from a mixture of coffee bean residue (so-called "dregs" obtained after roasting and grinding the coffee beans, and then removing soluble extract to form "instant" coffee powder) and chicken or turkey manures, and left in a heap or stack to undergo partial thermophilic decomposition to become active with a culture of fungi and bacteria.

Alternatively, a reaction promotion agent may be produced by using waste green coffee beans which usually are not suitable for the manufacture of instant or ground coffee. These waste coffee beans may be found in the country of origin. A quantity of green coffee beans are ground and soaked in a vat of cold water for a period of about 72 hours. The water is then drained and the soaked beans are mixed with chicken or turkey manures, which may contain straw or shavings, in a volume ratio of green coffee bean residue to fowl manures of 3:2. The mixture is formed into a large heap and using a high pressure steam cleaner, with the steam cleaner running as hot as possible with a maximum amount of steam and as little as possible hot water, the output jet is inserted into the heap, and left running for about 10 to 15 minutes. The jet is inserted all around the stack at about im centres, until the stack reaches a temperature of about 60 to 65C. If the stack does not maintain this temperature, a 10% solution of ammonia solution is sprayed onto the stack through a normal pesticide type spray, re-mixed thoroughly, and then stacked again as high as possible, with reintroduction of the steam jets in order to raise the temperature to the required temperature of 60 to 65C.

Although the observed breakdown rate in these heaps was vast, it also seemed to be almost infinite. For example, a heap which had been standing for about a year, on inspection was found to be still warm at about'40C. On closer inspection of the heaps, it could be seen that the outer surface was hard and cracked and resembled a thatched roof. This protected the heap from heavy rainfall and reduced the windblown dust, and beneath this skin there wa observed to be a thin anaerobic layer of about 8 to 10 cm thick, and beneath this the bulk of the heap was found to be almost entirely aerobic.

The large amounts of fowl waste in the heaps makes nitrogen a potentially unlimited resource to micro-organisms present. If composted in conventional windrows, or ASPs, much of this nitrogen would be given off as ammonia and escape into the atmosphere. However, on inspection, the heaps showed no sign of ammonia fumes until th6y were opened. It seems therefore that the excess ammonia produced in the centre of the heap is re-absorbed at the cooler extremities of the heap.

This may be the reason for the massive activity and longevity of the micro-organisms, as they live in a community which is much more stable than a small heap ecosystem. Another reason for the success of these heaps is believed to be due to the presence of the coffee bean residue, known as "dregs" in the instant coffee manufacturing industry, in admixture with the organic material, and it may be advantageous to the decomposing proc ess that the coffee bean residue is left to stand in the open for a few weeks before being mixed with the fowl waste.

On inspection of the heaps, it could be seen that various tropical alkalinophiles, such as neuroporasitophila, Peziza cerea and pyronema confluens could be found, as well as algae which are found growing at the top of the heap where a fumerol was seen to be emitting steam. A huge myxomycete (slime mould) Fuligo septica was also noted growing on the side of the heap, which was very unusual. It may be that tropical fungi such as these increase the rate of breakdown and result in the special nature of this strange compost mix.

These heaps which were inspected are controlled and caused to react in ways which are entirely contrary to perceived wisdom. First of all, the size of the heaps appears to be much too large, the heaps are not turned or aerated artificially in any way, and are not watered, all of which are believed to be essential operating parameters of a successful decomposing heap.

To date, no detailed experimentation has been carried out to investigate why the decomposing method works so well. Conventional wisdom has it that composting heaps should be made small and manageable, since increase in heap-size has been perceived to give rise to a problem with regard to the anaerobic layer formed on the outer surface of the heap. It has been assumed in the past that a heap size of about 250 to 350 cm by 150 to 250 cm has been optimal for performance, and no further experimentation into heap size has been carried out. However, in the very large heaps which have been investigated, which are the subject of this invention, the anaerobic layer is insignificant in proportion to heap size, and yet unexpectedly a significant advance in the decomposing processes achieved.

Further examples of decomposition of organic waste material will now be described.

The organic source material can comprise any suitable waste vegetable matter from agriculture and feed industries.

Ten tonnes of chicken manure on shavings as bedding was mixed with 10 tonnes of turkey manure on straw bedding, and were left to stand in a stack for 4 to 6 weeks. one tonne of hops supplied from a brewery i.e. after use in beer making, 1 tonne of ground bark granules of size 9 mm to 12 mm, and 10 tonnes of coffee ground residue derived as waste product from Nestles factory for making instant coffee by rbasting coffee grounds, comprise the constituent materials from which the heap is to be formed. The chicken and turkey manure is left in its stack, and a separate stack is formed by mixing the 10 tonne of coffee grounds, 1 tonne of hops and 1 tonne of ground bark. These were mixed well together, and left in a large stack as high as possible.

Then, using a high pressure steam cleaner, with the steam cleaner running as hot as possible with a maximum amount of steam and as little as possible hot water, the output jet is inserted into the stack of coffee grounds, bark and hops, and left running for about 10 to 15 minutes. The jet is inserted all around the stack at about 1m centres, until the stack reaches a temperature of about 60 to 65C. If the stack does not maintain this temperature, a 10% solution of ammonia solution is sprayed onto the stack through a normal pesticide type spray, re-mixed thoroughly, and then stacked again as high as possible, with reintroduction of the steam jets in order to raise the temperature to the required temperature of 60 to 65'C.

This stack is left to stand for about 3 days once the temperature has been maintained. At this time, signs of fungi and bacteria will become visible on the outside of the stack, comprising streptomycetes and antinomycetes, coloured orange, lemon to pale yellow, pale green and white.

Then, this steam-treated maturing stack of coffee grounds, hops and bark can be mixed with the stack of the 10 tonnes of chicken manure and 10 tonnes of turkey manure which has been allowed to stand for about 6 weeks. To this mixture there is then added about 2 cubic meters of coffee ground ash derived from the waste source from Nestles factory. All these ingredients have been mixed well together and then left in a large stack which is made as high as possible.

During the formation of this large stack derived from the two separately formed stacks, care should be taken not to compress the material in the stack by running into it with a loaded shovel.

This large stack is then left to stand and decompose, during which time the temperature will rise to approximately 70C and will then tend to maintain this temperature. The pH within the stack will remain at around 10 or above 10, and any excess nitrogen will be liberated in the form of ammonia gas. Liberation of ammonia can be detected by smell from outside the stack, and this will indicate that the pH within the stack is high. On the other hand, if there is no smell of ammonia gas, this will show that carbon is being liberated in the form of carbon dioxide gas, and these two means of liberation of carbon and nitrogen will continue until some equilibrium state is reached, at which time decomposition within the stack will start to take place rapidly in aerobic conditions and a thermophilic temperature range i.e. any temperature above WC.

With a thermophilic decomposition, the materials which are undergoing decomposition are maintained in aerobic conditions, and after a period of about 14 days the stack will become very active.

By this time, the material within the stack effectively comprises a catalyst for making organic fertiliser, when mixed with organic waste material. Thus, by using 10% of the mixture now being formed within the stack, together with 90% of organic material i.e. turkey and chicken manure at a 50:50 ratio along with straw or other organic material at a volume ratio of 1/3:113:113, the end product derived will be an organic fertiliser.

once the stack is operating as described above in aerobic conditions, and temperatures maintained in the higher thermophilic range i.e. 60 to WC, more organic material can be added to the stack in the volume.ratio as above. After about 21 days, the material will be ready for use.

Conveniently, the management of the decomposing action will take place by adding new organic material at one end of the stack in volumes as described above i.e. 10% of the existing stack by volume to 90% of new material, while an equivalent volume can be taken away from the stack at the opposite end as a finished product. Therefore, production of organic fertiliser can be produced in batches, with new material being added at one end of the stack, and end product being withdrawn from the opposite end, and with the contents of the stack intermediate the input end and the output end undergoing progressive decomposition from the input to the output end.

If it is found that there is any loss of nitrogen content of the finished product i.e.- liberated as ammonia gas which can be smelt, a small amount of sulphur can be added to bring down the pH to about 6.5 i.e. slightly acidic. This sulphur will turn the ammonia gas into ammonium sulphate, which will be a useful fertiliser in itself. However, the dosing with sulphur should be kept to as small a level as possible, since ammonium sulphate is readily water soluble, and if this should be present in too large amounts in the organic fertiliser, it could have too strong an effect on plants being treated with a fertiliser and may harm the plant growth, rather than promote it.

The carbon to nitrogen ratio in the finished product will depend upon the rate of available nitrogen in the composting material being locked up in bacteria cell walls.

Nutrients and trace elements in the finished product also will become "locked" up in the dead bacteria cell walls, and not being water soluble, they are readily available for use by plant life as and when required. Any excess nutrients not required by a first crop will remain in the soil for a later crop, rather than becoming leached into the soil and then eventually passing away to water courses.

If it is found that the conductivity of the finished product is too high, it can be mixed with a suitable nutrient free bulking agent to the ratios described above, to bring the conductivity levels down to within the M.A. F.F. index levels for horticultural use, or for spreading on fields.

When operating the 11keldah111 method of analysis, on the end product, this will give satisfactory results, because the nutrients present are not water soluble.

In the production of organic fertiliser from organic waste materials by decomposing in "heaps" as described above, it is particularly advantageous to apply a coating or covering layer on the decomposing heap. This effectively functions as a thatch or cover on the decomposing material, and prevents excessive rainwater being admitted to the interior of the heaps, which could slow down or interfere with the decomposing process. The thatch or cover also forms a crust, which contains the contents of the decomposing heap, and has been found to have a beneficial effect on the decomposing process. The exact mechanism by which this improvement is achieved is not presently clear. The covering or coating layer may comprise the so-called "catalyst" formed in the initial stages of the decomposing process, prior to admixture with additional amounts of organic waste material.

Some of the benefits of the decomposing technique according to the invention are as follows:

1. Increased acceleration of the decomposing process; 2. Confinement of pathogens, parasites and harmful bacteria; 3. Elimination or reduction of generation of unpleasant odours, such as ammoniacal gases or hydrogen sulphide, by the thatch or cover acting as a biofilter; 4. Increasing the temperature generated within the heap of decomposing materials; 5. Minimise problem of leaching of nutrients into the soil and eventually passing away into water courses; 6. Inhibiting invasion of the decomposing material in the stack by wildlife, by reason of the top crust or thatch.

In broad terms, the invention comprises a method of decomposing organic and / or inorganic material by using a catalyst which is added to the waste material to be decomposed.

The catalyst is made from a mixture of some or all of the following materials:

1. Activated carbon; 2.

3.

4.

5.

Urea; uric acid; Unactivated carbon; Residue from roasted coffee beans i. e. coffee bean residue produced during manufacture of instant coffee; 6. Ash from burnt coffee beans, with or without alkali.

After adding the catalyst to the material to be decomposed, and forming a mixture in a heap, this is left in a stack or windrow to allow decomposition to take place.

Among the benefits of the process are:

1. High temperatures within the thermophilic range i.e. in excess of WC are generated, and maintained within the heaps, creating a new environment for the activation of new species of thermophilic alkaline bacteria.

2. Confinement of pathogens, parasites and harmful bacteria.

_ 3. Higher temperatures generated evaporate excess moisture and thereby prevent leaching.

4. Elimination of unpleasant odours.

5. Discouraging or preventing the production of methane gas.

6. The production of new species of antibiotics, penicillin and other drugs.

7. The activation of new species of bacteria producing enzymes for clinical, medical or other uses.

8. A self oxygenating process without the need to aerate the material by mechanical means.

EXAMPLE - A Hiqh Ouality Compost.

Some plant species, particularly those not native to a particular environment or country, require special conditions necessary for normal and sustainable growth. The soils and composts available are often very different to,the native soil and it can be very difficult and expensive to reproduce a suitable growth environment for these plants. However, the method of the invention can provide a high quality compost and a growth environment suitable for species of plant or life not previously sustainable in some foreign soils.

One high quality compost, particularly suitable for supporting growth of truffles and shiitake mushrooms, may be produced using the method of the invention. These fungi are particularly difficult to grow in a foreign environment. A compost is formed by mixing equal quantities of turkey or chicken manure (or a 50%-50% mixture of the two), coffee residue or dregs without ash, and hops. It is preferable, though not essential, that the hops have been allowed to stand in a heap for a few weeks before being used. The mixture is formed into a large heap and left for a period of at least fourteen days. During this time the active decomposing environment unique to the method of the invention degrades the mixture into a medium suitable for sustaining growth of the truffles and shiitake mushrooms. Coffee filter cake, distillery waste and hops grains may also be used in the initial mixture as suitable compost forming waste materials.

- Q-

Claims (14)

1. A method for the production of organic fertiliser from a bulk source of organic material, comprising mixing a tannin-containing reaction promotion material, and / or an activated carbon residue with the bulk material to form a heap of the mixed material, and allowing at least part of the heap of mixed material to undergo aerobic decomposition for a sufficient period until this part has broken down or decomposed to an extent to render this part suitable for use as an organic fertiliser.

2. A method according to Claim 1, comprising applying a coating or covering layer over the heap prior to allowing aerobic decomposition of at least part of the heap of mixed material.

3. A method according to Claim 1 or 2, in which said part of the heap of mixed material, after it has broken down or decomposed, is then mixed with a further supply of organic material to form a further heap which will then undergo accelerated decomposition.

4. A method according to any one of Claims 1 to 3, in which the organic waste material includes chicken and turkey manure.

5. A method according to Claim 4, in which the manure is mixed with straw.

6. A method according to any one of Claims 1 to 3, in which the organic waste material includes sewage sludge derived from human waste, or animal offals of a type not suitable for human consumption.

7. A method according to Claim 1, in which the bulk source of organic material includes waste plant material.

8. A method according to Claim 7, in which the waste plant material includes hops after use in a brewery for making beer.

9. A method according to any one of Claims 2 to 8, in which the coating or covering layer shields the outer surface of the heap, and is allowed to become hard and thereby protect the heap from heavy rainfall, and to reduce the generation of wind blown (Tdst.

10. A method according to any one of the preceding claims, in which the tannin-containing reaction promotion material comprises coffee bean residue derived as a waste product from the manufacture of instant coffee.

11. A method according to Claim 1, in which the tannincontaining material comprises tea leaf residue.

12. A method according to Claim 1, in which the tanning-containing reaction promotion material is formed from a mixture of coffee bean residue obtained after roasting and grinding coffee beans, and then removing soluble extract suitable to form "instant" coffee powder, and which is mixed with chicken or turkey manures, and then left in a heap or stack to undergo partial thermophilic decomposition to become active with a culture of fungi and bacteria.

13. A method according to Claim 1, in which the reaction promotion material is derived from waste green coffee beans usually not considered suitable for the manufacture of instant or ground coffee, and which is ground and soaked in a vat of cold water, the water is then drained, and the soaked beans are then mixed with chicken or turkey manures, which may contain straw or shavings, prior to application of the mixture into a large heap into which high pressure steam is introduced until the stack reaches a temperature of about 60 to 65'C.

14. A method according to Claim 13, in which a 10% solution of ammonia is sprayed onto the stack if the stack does not maintain the temperature of 60 to 65'C.