WO2007133093A2

WO2007133093A2 - Method for decomposing organic waste

Info

Publication number: WO2007133093A2
Application number: PCT/NO2007/000176
Authority: WO
Inventors: Thor Olav RØRHEIM
Original assignee: Biozymatic Sus
Priority date: 2006-05-16
Filing date: 2007-05-16
Publication date: 2007-11-22
Also published as: WO2007133093A3

Abstract

The present invention relates to decomposition processes of organic waste and in particular production of useful by products resulting from such processes. In particular the present invention relates to addition of active components that result in efficient decomposition processes. These methods are useful in production of bio fuels and fertilizers. The present invention in particular relates to addition of active components that result in more efficient decomposition processes.

Description

Method for decomposing organic waste

Technical field of the invention

The present invention relates to decomposition processes of organic material and in particular production of useful by products resulting from this process. In particular the present invention relates to addition of active components to biowaste resulting in efficient decomposition processes. These active components are preferably derived from marine organisms such as crustaceans.

Background of the invention

Increasing global energy requirements and heightened environmental awareness have resulted in increasing focus on alternatives to fossil fuels as energy sources. Human activity with respect to combustion of fossil fuels contributes significantly to the total amount of carbon dioxide (CO₂) released into the atmosphere. Carbon dioxide is purported to be a so-called "greenhouse gas" and thus to contribute to global warming.

In contrast to energy production by combustion of fossil fuels, energy production by combustion of contemporary biomass or fuels derived from such biomass is regarded as being "CO₂-neutral", since the amount of CO₂ released by combustion of a given amount of such biomass corresponds to the amount of CO₂ which was originally taken up from the atmosphere during the build-up of that amount of biomass.

Decomposition of organic material through microbiological activity is a natural process that may result in production of biogas, and/or bioethanol, and/or heat, and/or fertilizer. Decomposition is, roughly speaking, carried out at anaerobic or aerobic conditions. However, in practice there will almost always be both anaerobic as well as aerobic processes taking place no matter if decomposition is carried out under aerobic or anaerobic conditions. It follows that aerobic processes are carried out in the presence of oxygen and anaerobic processes are carried out without addition of oxygen. Aerobic processes usually result in heat production, whereas anaerobic processes often require additional heating to be sufficiently efficient. The by-products from these processes can sometimes be used as a soil fertilizer/soil conditioner.

Additives such as e.g. starter culture, enzymes, lime, minerals, nitrogen, phosphorus, fermentative sugars, means for adjusting pH, waste food, hay, straw, etc. are usually required in order to facilitate decomposition of organic material. However, key additives such as e.g. starter cultures tend to be relatively expensive. Furthermore, commonly used additives are generally not sufficiently efficient for inducing production of bio fuels and/or sufficiently efficient for catalysing the decomposition processes. As a result, commonly known processes for producing environmentally friendly bio fuels cannot yet compete with fossil fuels in a sufficiently efficient manner. As a consequence, only a very small fraction of fossil fuel consumption has thus far been replaced with bio fuel consumption.

From US 5531898 it is e.g. known to add various commercially available enzymes as well as B.subtilis and P.fluorescens to sewage in order to make the decomposition process of sewage more efficient. However, there is a need in the art for improved methods as well as inexpensive means for decomposing organic material/waste.

From JP 2001026488 it is known to prepare mineral enriched fertilizer by adding fossil seashells to organic waste. This fertilizer is free from environmental pollution. However, there is no evidence that fossil seashell addition result in more efficient decomposition processes.

Hence, improved methods for producing bio fuels are highly desirable. In particular, inexpensive means for improving bio fuel production methods are highly desirable. It is believed that improved bio fuel production methods would potentially encourage development of novel products that are based on bio fuel consumption rather than fossil fuel consumption. It is furthermore desirable to obtain improved methods for decomposing organic material as well as improved methods for producing soil amendments.

Summary of the invention

Thus, an object of the present invention is to provide means for decreasing production of greenhouse gases.

In particular, it is an object of the present invention to provide means for efficient bio fuel production. It is furthermore an object to provide means for cost efficient and thus more competitive bio fuel production. And finally it is an object to provide improved methods for decomposing organic material.

The present invention relates to a method of decomposing organic material, said method comprising a step of mixing active components derived from crustaceans with said organic material followed by incubation of said mixture.

Addition of active components derived from crustaceans surprisingly results in an improved decomposition process as shown in the examples and figures. Furthermore, for most applications this material appears to be highly cost efficient. As a consequence, the present invention is providing more efficient tools for production of bio fuels as well as soil conditioners.

Brief description of the figures

Fig 1. shows the effect on total gas production (ml) by increasing the incubation temperature in cow manure samples from 2O⁰C to 35°C. The figure is based on all anaerobic samples in the experimental plan, grouped by identical values of the displayed variable, in this case temperature; Each group thus consists of samples incubated under anaerobic conditions at either 20 or 35°C. The figure thus displays the average effect of the temperature increase - across all other variations in sample composition - a principle usually referred to as "factorial design". The principle of factorial design implies that all design variables are varied interdependently, according to the experimental plan. Groups of samples representing one level of a given variable thus represent many different combinations of other design variables at different levels. The figure displays the groups at 20⁰C and 35⁰C, respectively, and so shows the average effect of this temperature increase. Each pair of bars represent samples analysed at 4, 11, 16, and 21 days, respectively. The left bars represent samples at 20°C, and the bars to the right represent samples at 35°C. It appears that incubation at 35°C result in an increased gas production compared to incubation at 20⁰C.

Fig. 2. shows the effect on total gas production (ml) of adding 10% hay to cow manure samples under anaerobic conditions. The figure is based on factorial design calculations. The principle of factorial design implies that all design variables are varied interdependently, according to the experimental plan. Groups of samples representing one level of a given variable thus represent many different combinations of other design variables at different levels. This figure displays the groups with 0 and 10% hay, respectively, and thus shows the average effect of the addition of hay. Each pair of bars represent samples analysed at 4, 11, 16 and 21 days, respectively. The left bars represent samples without hay, and the bars to the right represent samples containing 10% hay. It appears that addition of hay result in an increased gas production.

Fig. 3. shows the effect on total gas production (ml) of adding 10% krill to cow manure samples under anaerobic conditions. The figure is based on factorial design calculations. The principle of factorial design implies that all design variables are varied interdependently, according to the experimental plan. Groups of samples representing one level of a given variable thus represent many different combinations of other design variables at different levels. This figure displays the groups with 0 and 10% krill, respectively, and thus shows the average effect of the addition of krill. Each pair of bars represent samples analysed at 4, 11, 16 and 21 days, respectively. The left bars represent samples without krill, and the bars to the right represent samples with 10% krill. It appears that addition of krill result in an increased gas production.

Fig. 4. shows the effect on gas production rate (ml gas produced between the measuring points) of adding 10% krill to cow manure samples under anaerobic conditions. The figure is based on factorial design calculations. The principle of factorial design implies that ail design variables are varied interdependently, according to the experimental plan. Groups of samples representing one level of a given variable thus represent many different combinations of other design variables at different levels. This figure displays the groups with 0 and 10% krill, respectively, and thus shows the average effect of the addition of krill. Each pair of bars represent samples analysed at 4, 11, 16 and 21 days, respectively. The left bars represent samples without krill, and the bars to right represent samples with 10% krill. It appears that addition of krill result in an increased gas production activity during the entire assay period.

Fig. 5. shows the effect on gas production rate (ml produced between the measuring points) of adding 10% hay to cow manure samples under anaerobic conditions. The figure is based on factorial design calculations. The principle of factorial design implies that all design variables are varied interdependently, according to the experimental plan. Groups of samples representing one level of a given variable thus represent many different combinations of other design variables at different levels. This figure displays the groups with 0 and 10% hay, respectively, and thus shows the average effect of the addition of hay. Each pair of bars represent samples analysed at 4, 11, 16 and 21 days, respectively. The left bars represent samples without hay, and the bars to the right represent samples containing 10% hay. It appears that addition of hay result in an increased gas production - at least during the first couple of weeks.

Fig. 6. shows the effect on the gas production rate (ml produced between measuring points) of increasing incubation temperature from 20⁰C to 35⁰C under anaerobic conditions. The figure is based on factorial design calculations. The principle of factorial design implies that all design variables are varied interdependently, according to the experimental plan. Groups of samples representing one level of a given variable thus represent many different combinations of other design variables at different levels. The figure displays the groups at 20⁰C and 35°C, respectively, and thus shows the average effect of this temperature increase. Each pair of bars represent samples analysed at 4, 11, 16 and 21 days, respectively. The left bars represent samples at 20⁰C, and the bars to the right represent samples at 35°C. It appears that elevated temperatures result in an increased gas production during the entire assay period. Fig. 7. shows the effects of various experimental factors on total gas production after 21 days under anaerobic conditions. The figure is based on factorial design calculations. The bars represent the average effect of all design variables. It appears that krill addition results in an increased gas production, whereas industrial hygienized food waste addition results in slightly decreased gas production. Addition of lime or starter culture results in a slightly increased gas production. High temperature (35°C) led to higher gas production than low temperature (20⁰C)

Fig. 8. shows the effects from various experimental factors on pH-change after 2 days of incubation at aerobic conditions. The figure is based on factorial design calculations. The bars represent the average effect of all design variables (0/10% krill, 0/10% food waste, 0/10% hay, 0/5% lime, and 20/35⁰C, respectively). It appears that krill addition resulted in the most pronounced change in pH.

Fig. 9. Effects and interaction effects on the total bacterial count (CFU) after 21 days of incubation with various additives and conditions on the aerobic degradation of cow manure. The figure is based on factorial design calculations. It appears that the bacterial growth is efficiently stimulated by krill addition and raised temperatures.

Fig. 10. Gas concentration (% pr. volume) in all anaerobic samples at days 3 and 22, respectively. It appears that methane can be detected on day 3 and in increased amounts on day 22.

Fig. 11. CO₂ production (ml) under anaerobic incubation measured at day 3 and day 22, respectively. The five bars represent addition of 0%, 5%, 10%, 20% and 30% krill, respectively to the cow manure. Increase of krill content result in an increased CO₂ production.

Fig. 12. Methane production (% methane of the gas volume) under anaerobic conditions measured at day 3 and 22, respectively. The five bars represent addition of 0%, 5%, 10%, 20% and 30% krill, respectively to the cow manure. It appears that the methane production is gradually increased when the krill content is increased from 0 to 5%.

Fig. 13. Effect of krill addition on the total gas production (ml) days 2, 3, 7, 9, and 14, respectively. The samples were incubated under anaerobic conditions at 35°C. The five bars represent addition of 0%, 5%, 10%, 20% and 30% krill to the cow manure, respectively. It appears that the total gas production is increased with increasing krill contents.

Fig. 14. Effect of salmon fillet addition (10%) on the total gas production (ml) in anaerobic degradation of cow manure. The samples were incubated under anaerobic conditions at 20/35⁰C. It appears that salmon fillet addition result in an increased gas production during the entire assay period.

Fig 15. Effect of temperature increase (from 20⁰C to 35°C) on the rate of gas production (ml produced between measuring points) in anaerobic degradation of cow manure. It appears that the temperature increase result in an increased gas production in the beginning of the assay period.

Fig 16. Effect of krill addition on the rate of gas formation (ml produced between measuring points) in anaerobic degradation of cow manure. The five bars represent addition of 0%, 5%, 10%, 20% and 30% krill to the cow manure, respectively. It appears that increasing amounts of krill stimulate the gas production rate, in particular during the first couple of weeks of the assay period.

Fig 17. Effect of 10% salmon fillet addition on the rate of gas formation (ml produced between measuring points) in anaerobic degradation of cow manure. It appears that salmon fillet addition results in a stimulated gas production during the first week, whereas krill addition stimulated gas production during the entire assay period as previously shown. These results suggest that krill addition result in addition of unidentified active components.

The present invention will now be described in more detail in the following. Detailed description of the invention

Definitions:

Prior to discussing the present invention in further details, the following terms and conventions will first be defined:

Organic material: Organic material is anything produced only by living organisms, and containing primarily carbon and hydrogen. According to the present invention however, organic material is primarily biodegradable waste originating primarily from plant and/or animal sources, and which may be broken down by other living organisms. Examples thereof include municipal solid waste such as e.g. green waste, food waste, paper, waste, and biodegradable plastics. Other examples of biodegradable waste include human waste, manure, sewage, slaughterhouse waste, etc.

Biodegradable waste is a little recognised resource. Through correct waste management, often using the processes of aerobic/anaerobic digestion/decomposition/fermentation/composting, it can be converted into valuable products.

Anaerobic digestion converts biodegradable waste into several products, including biogas, which can be used to generate renewable energy or heat for local heating, and soil amendment (digestate). Under certain conditions, biodegradable waste may also be converted into bioethanol.

Decomposition/fermentation/decomposition/composting/incubation: According to the present invention, decomposition, etc. commonly refer to the reduction of formerly living organisms into simpler forms of matter as well as the breaking down of larger molecules into smaller molecules or atoms. Decomposition begins at the moment of death, caused by two factors: autolysis, the breaking down of tissues by the organisms own internal chemicals and enzymes; and breakdown of tissues by microorganisms such as bacteria, yeast, etc. The terms decomposition and fermentation are herein used interchangeably, although fermentation processes primarily refer to the method of inoculating a starter culture, i.e. a fermentative organism, into a selected growth medium such as e.g. biodegradable waste and the subsequent incubation/fermentation process. Often, industrial fermentation processes are carried out under controlled and predefined conditions with regards to temperature, incubation time, stirring, pH, water content, presence or absence of oxygen, inoculation, organic medium, etc.

Fermentation processes can be carried out under essentially anaerobic conditions, meaning that no oxygen is added to the system during the incubation time.

Normally, anaerobic processes are carried out either in closed vessels or in vessels with a flow of non-oxygen gas such as e.g. He, N₂, etc. Aerobic processes are usually carried out in the presence of oxygen (1-100%, such as e.g. 1-50%, 1- 25%, 10-25%, 15-25%, 20-25%, preferably under stirring. Aerobic processes usually result in heat production, i.e. aerobic processes often take place at elevated temperatures meaning that further warming might be unnecessary. In contrast, it is often necessary to perform anaerobic processes at elevated temperatures, e.g. by warming, in order to ensure that the process will be sufficiently efficient.

The terms decomposition, fermentation, and composting are herein used interchangeably although composting usually refer to the natural process of producing compost through mainly aerobic decomposition of biodegradable organic matter. The decomposition is performed primarily by aerobes, although larger creatures such as ants, nematodes, and oligochaete worms may also contribute.

Industrial composting is the controlled decomposition of organic matter. Rather than allowing nature to take its slow course, a composter provides an optimal environment in which decomposers can thrive. To encourage the most active microbes, a compost pile needs the correct mix of the following ingredients: C, N, O₂, and water. Aerobic bacteria produce less odour and fewer destructive greenhouse gases than their anaerobic counterparts in addition to resulting in faster decomposition compared with their anaerobic counterparts. The incubation step according to the present invention may be in principle be carried out at temperatures ranging from about 0-100⁰C, such as e.g. 5-75°C, 10-50⁰C, 10-45⁰C, 10-40⁰C, 10-35⁰C, 20-40⁰C, 20-35⁰C, and 25-35°C. If the incubation is carried out at temperatures above about 40⁰C, addition of thermophilic microorganisms is preferred. The temperature optimum of many applications is about 35°C.

The length of the incubation step according to the present invention may in principle range from 5 minutes to 5 months. However, preferred incubation times range from about 30 minutes to 60 days, preferably 1 to 40 days, more preferably 7 to 40 days, even more preferably 1 to 4 weeks, and most preferably 2 to 4 weeks.

Crustaceans: The crustaceans (Crustacea) are a large group of arthropods, comprising approximately 52,000 described species. They include various familiar animals, such as lobsters, crabs, shrimp, crayfish and barnacles. The majority are aquatic, living in either fresh water or marine environments, but a few groups have adapted to terrestrial life, such as terrestrial crabs, terrestrial hermit crabs and woodlice. The majority are motile, moving about independently, although a few taxa are parasitic and live attached to their hosts (including sea lice, fish lice, whale lice, tongue worms, and Cymothoa exigua, all of which may be referred to as "crustacean lice"), and adult barnacles live a sessile life - they are attached head-first to the substrate and cannot move independently.

Active components derived from crustaceans: The present invention is based on the surprising observation that addition to organic material, such as e.g. organic waste, of active components derived from crustaceans result in an accelerated decomposition process. Active components are defined as material or components that have the capability of increasing the decomposition rate. The active components have not been characterized yet but are believed to include e.g. digestive enzymes as well as microorganisms.

For practical reasons it is preferred to use whole animals. However, it may be desirable to use fully or partly milled/pulverized/homogenized/comminuted/liquid crustacean preparations. It is furthermore preferred to use organisms that have not been subject to any biochemical inactivation procedures, such as e.g. cooking or steaming. It is thus desirable to use fresh material, although it may in many cases be practical to use crustacean material that has been frozen prior to use.

Obviously, the present invention also embraces use of active components that have been isolated, and possibly also multiplied, from crustaceans as well as any mixtures thereof, including mixtures of whole animal preparations enriched with active crustacean components. Examples thereof include enzyme enriched preparations prepared by biochemical purifications methods using crustaceans as a raw material. Crustacean enzyme preparations may also be obtained employing recombinant methods. Another example includes microorganisms, preferably bacteria, isolated from the crustacean gut. It follows that such microorganisms can be subject to further cultivation resulting, in theory, in an unlimited supply of crustacean gut microorganisms. It likewise follows that active components derived from crustaceans may as well be mixed with other traditional decomposition additives, such as e.g. "starter cultures" mainly comprising bacterial cultures, enzymes, means for adjusting pH, waste food, hay, straw, minerals, fermentable sugars, etc.

Apart from contributing with various active components useful in fermentation/degradation processes, crustacean organisms furthermore contribute with important nutrients such as lipids, carbohydrates, proteins that promote bacterial growth and thus decomposition processes.

According to the present invention, the amount of crustaceans and/or crustacean components as calculated by weight of the crustacean/organic material mixture may in principle vary from less than 1% up to more than 99%. Preferably, the amount is 1-50%, or 1-40%, or 1-30%, or 2-25%, or 2-20%, or 3-20%, or 3- 15%, or 5-25%, or 5-20%, or 5-15%, or 5-15%.

Krill: Krill are small shrimp-like crustaceans. These crustaceans are important organisms of the zooplankton, particularly as food for baleen whales, mantas, whale sharks, crabeater seals and other seals, and a few seabird species that feed almost exclusively on them. Another name is euphausiids, after their taxonomic order Euphausiacea. The name krill comes from the Norwegian word krill meaning "young fry of fish".

Krill occur in all oceans of the world. They are considered keystone species near the bottom of the food chain because they feed on phytoplankton and to a lesser extent zooplankton, converting these into a form suitable for consumption by many larger animals for whom krill makes up the largest part of their diet. In the Southern Ocean, one species, the Antarctic Krill, Euphausia superba, makes up a biomass of hundreds of millions of tonnes, similar to the entire human consumption of animal protein. Most of the species display large daily vertical migrations making a significant amount of biomass available as food for predators near the surface at night and in deeper waters during the day. In other words, krill potentially constitutes an almost endless source of inexpensive and easily accessible nutrients.

Commercial fishing of krill is done in the Southern Ocean and in the waters around Japan. The total global production amounts to 150 - 200,000 tonnes annually, most of this from the Scotia Sea. Most krill is used for aquaculture and aquarium feeds, as bait in sport fishing, or in the pharmaceutical industry. It thus follows that an interesting aspect of the present invention is to use the otherwise almost useless krill waste products from e.g. the pharmaceutical industry and use it as a valuable resource according to the present invention.

In Japan and Russia, krill is also used for human consumption and known as okiami in Japan. In health food stores, krill oil is marketed as a nutritional supplement and is believed to be beneficial for joints and the immune system. Krill taste salty and somewhat stronger than shrimp. Excessive intake of okiami may cause diarrhea.

It thus appears that commercial exploitation of krill, in particular as a source of nutrients, is not entirely straight forward, even though krill potentially represents a valuable and renewable inexpensive resource present in almost unlimited amounts. The present invention thus provides for a novel use of this product that ultimately may lead to a reduced CO₂-release. In connection with the present invention, it is preferable to use krill that have been frozen very quickly, preferably almost immediately, after catching in order to keep the biologically active components as intact and active as possible. Alternatively, the krill may also be stored at temperature close to the freezing poing point such as 5, 4, 3, 2, 1, or 0 ⁰C.

Bio fuels: Bio fuel is derived from biomass — recently living organisms or their metabolic byproducts, such as manure from cows. It is a renewable energy source, unlike other natural resources such as petroleum, coal, and nuclear fuels. Like coal and petroleum, biomass is a form of stored solar energy. According to the present invention, the term bio fuel parimarily refers to biogas and/or bioethanol.

Biogas: Biogas typically refers to a (bio fuel) gas produced by the anaerobic digestion or fermentation of organic matter including manure, sewage sludge, municipal solid waste, biodegradable waste or any other biodegradable feedstock, under anaerobic conditions. Biogas is comprised primarily of methane and carbon dioxide. Biogas can be used as a vehicle fuel or for generating electricity. It can also be burned directly for cooking, heating, lighting, process heat and absorption refrigeration.

Bioethanol or ethanol fuel: Ethanol fuel is a bio fuel alternative to gasoline. It can be combined with gasoline in any concentration up to pure ethanol (ElOO). Anhydrous ethanol, that is, ethanol with at most 1% water, can be blended with gasoline in varying quantities to reduce consumption of petroleum fuels and in attempts to reduce air pollution. Worldwide automotive ethanol capabilities vary widely and most spark-ignited gasoline style engines will operate well with mixtures of 10% ethanol.

Ethanol can be mass-produced by fermentation of sugar or by hydration of ethylene from petroleum and other sources. Current interest in ethanol lies in production derived from crops (bio-ethanol), and there's discussion about whether it is a sustainable energy resource that may offer environmental and long-term economic advantages over fossil fuels, like gasoline or diesel. It is readily obtained from the starch or sugar in a wide variety of crops. In general, however, the price of bioethanol has not been sufficiently competitive with that of fossil fuels and there is therefore a need in the art to identify tools for reducing bioethanol production costs.

The present invention thus embraces addition of crustaceans (e.g. krill) and/or their active components to improve the bioethanol fermentation process.

Fertilizer/soil conditioner: Fertilizers are compounds given to plants to promote growth; they are usually applied either via the soil, for uptake by plant roots, or by foliar feeding, for uptake through leaves. Fertilizers according to the present invention are organic in nature (composed of organic matter, i.e. carbon based). Examples of naturally occurring organic fertilizers include manure, slurry, worm castings, peat, seaweed, sewage, and guano.

Fertilizers according to the present invention typically provide, in varying proportions, the three major plant nutrients (nitrogen, phosphorus, and potassium), humus soil, the secondary plant nutrients (calcium, sulfur, magnesium), and sometimes trace elements (or micronutrients) with a role in plant nutrition: boron, chlorine, manganese, iron, zinc, copper, and molybdenum.

In connection with the present invention, soil conditioner or soil fertilizer refer to the solid (or semi-solid) by-product that is obtained as a result of the decomposition process. This product is in most cases useful as a soil conditioner/fertilizer. However, the solid by-products may not be particularly useful for these purposes if the decomposition process has been performed on basis of organic matter contaminated with toxic substances such as e.g. heavy metals, etc. According to the present invention it is thus preferable to use organic material that has not been contaminated with toxic substances such as e.g. heavy metals.

Furthermore, under some conditions fertilizers according to the present invention may also replace sphagnum as a soil conditioner. There is some question about the sustainability of large-scale Sphagnum harvesting. In particular, the extraction of large quantities of moss is a threat to raised bogs. The present invention thus offers an alternative to Sphagnum harvesting. Microorganisms/starter culture: Decomposition processes yielding biogas are primarily performed by methane-producing microorganisms (also known as methanogens) which constitute a unique group of prokaryotes which are capable of forming methane from certain classes of organic substrates, methyl substrates (methanol, methylamine, dimethylamine, trimethylamine, methylmercaptan and dimethylsulfide) or acetate (sometimes termed acetoclastic substrate) under anaerobic conditions. The methane-producing microorganisms according to the present invention may be derived from crustaceans and/or they may be derived from other sources.

Methanogens are found within various genera of bacteria, and methanogenic bacteria of relevance in the context of the present invention include species of Methanobacterium, Methanobrevibacter, Methanothermus, Methanococcus, Methanomicrobium, Methanogenium, Methanospirillum, Methanoplanus,

Methanosphaera, Methanosarcina, Methanolobus, Methanoculleus, Methanothrix, Methanosaeta, Methanopyrus or Methanocorpusculum; some of these, notably species of Methanopyrus, are highly thermophilic and can grow at temperatures in excess of 100⁰C. Only three genera of methanogenic bacteria, viz. Methanosarcina, Methanosaeta and Methanothrix, appear to contain species capable of carrying out the acetoclastic reaction, i.e. conversion of acetate to methane (and carbon dioxide). It will be appreciated that useful methanogenic bacteria can be selected from a genetically modified bacterium of one of the above useful organism having, relative to the organism from which it is derived, an increased or improved methane producing activity.

Fermentative microorganisms include yeasts such as e.g. Candida, Kluyveromyces, Pichia, Saccharomyces, Schizosaccharomyces, Yarrowia, Acremonium, Aspergillus, Aureobasidium, Cryptococcus, Filibasidium, Fusarium, Humicola, Magnaporthe, Mucor, Myceliophthora, Neocallimastix, Neurospora, Paecilomyces, Penicillium, Piromyces, Schizophyllum, Talaromyces, Thermoascus, Thielavia, Tolypocladium, or Trichoderma. Saccharomyces species include S. carlsbergensis, S. cerevisiae, S. diastaticus, S. douglasii, S. kluyveri, S. norbensis or S. oviformiss. Aspergillus species include A. aculeatus, A. awamori, A. foetidus, A. japonicus, A. nidulans, A. niger, A. oryzae. Fusarium species include F. bactridioides, F. cerealis, F. crookwellense, F. culmorum, F. graminearum, F. graminum, F. heterosporum, F. negundi, F. oxysporum, F. reticulatum, F. roseum, F. sambucinum, F. sarcochroum, F. sporotrichioides, F. sulphureum, F. torulosum, F. trichothecioides, and F. venenatum. Other yeast species include e.g. Humicola insolens, Humicola lanuginosa, Mucor miehei, Myceliophthora thermophila, Neurospora crassa, Penicillium purpurogenum, Trichoderma harzianum, Trichoderma koningii, Trichoderma longibrachiatum, Trichoderma reesei, or Trichoderma viride.

Digestive enzymes: Enzymes are proteins that catalyze (i.e. accelerate) chemical reactions. Digestive enzymes are defined as enzymes with the capability of accelerating break down processes of various nutrients. Examples of digestive enzyme classes include: proteinases, peptidases, lipases, carbohydrases, nucleases, etc.

The present invention thus relates to a method of decomposing organic material, said method comprising a step of mixing active components derived from crustaceans with said organic material followed by incubation of said mixture.

In one embodiment, the crustacean components may be fully or partly derived from krill. In a second embodiment, the incubation is performed under essentially anaerobic conditions. In a third embodiment, the incubation is performed under essentially aerobic conditions. According to a fourth embodiment, one or more additives are added to the mixture. The aim of such additives is in general to obtain a more efficient decomposition process, preferably resulting in production of bio fuel. However, it may also be an aim to improve the composition of a fertilizer. Such additives are preferably selected from the group consisting of: digestive enzymes, microorganisms, minerals, nitrogen, phosphorus, fermentative sugars, waste food, hay, straw, acidic compounds, and basic compounds.

In a preferred embodiment, the method according to the present invention is used in connection with a method of producing biogas. This method preferably comprises the step of collecting a fraction of the resulting biogas and using said fraction of biogas to heat the incubation mixture such that external heating of the process may be unnecessary. In another preferred embodiment, the method according to the present invention is used in connection with a method of producing fertilizer.

In yet another preferred embodiment, the method according to the present invention is used in connection with a method of producing bioethanol.

In a final aspect, the present invention relates to use of active components derived from crustaceans for catalyzing decomposition of organic material.

Another aspect relates to compositions that can be obtained using a method according to the present invention. Such compositions are preferably used as fertilizer compositions.

It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.

All patent and non-patent references cited in the present application, are hereby incorporated by reference in their entirety.

The invention will now be described in further details in the following non-limiting examples.

Examples

Example 1

General outline of the experiments

The experimental system was based on incubation of 50% fresh cow manure for up to about three weeks. Some samples furthermore contained various additives. The cow manure was collected from dairy cows at the Norwegian University of Life Sciences and were mixed with an equal volume of tap water and coarsely comminuted with a Ultra-Thurrax homogenizer. All organic ingredients (including diluted cow manure) were homogenized in a Waring blender.

Anaerobic fermentation was carried out by incubation of 50 g samples in 120 ml gas-tight bottles supplied with a septum. Total gas production was assessed by measuring the total volume of gas. This was measured by injecting a canula (fitted onto a syringe) into the septum, and measuring the volume displaced when the system was equilibrated at ambient pressure. The composition of the produced gas was analysed by Gas Chromatography.

The model system for anaerobic degradation of cow manure consisted basically of 50 g of diluted and homogenized cow manure in a 120ml glass bottle fitted with a gas-tight rubber septum fastened by an aluminium cramp seal. The bottles were incubated at constant temperatures (2O⁰C and 35⁰C). Gas samples were taken by injecting a syringe into the septum.

The model system was monitored by measurement of gas volume production at regular intervals, and by analysis of gas composition at two selected time points.

Aerobic degradation was carried out by incubation of 100 g samples in 500 ml Erlenmeyer flasks with loose aluminium foil covers, and under continuous stirring at either 20 or 35°C. Decline in pH, as a measure of decomposition, was measured twice. Decline in pH is a result of hydrolytic activity and metabolic acid production by microbiological processes. The model system was analysed after two days of incubation by measuring the total number of colony forming units (CFU) and the pH-change.

Example 2

Assessment of the effect of various additives

In the first experimental setup, the following variables (factors) were analyzed for 21 days under anaerobic and aerobic conditions, respectively: . _

19

• Krill (0 and 10%)

• Hygienized food waste (0 and 10%) prepared at a municipal waste rendering plant, for use as biogas substrate in a reactor at the same plant.

• Lime (0 and 5%) CaCO₃ of p. a quality was used. • Hay (0 and 10%) collected from a local farm.

• Starter culture (0 and 10%) (only with anaerobic degradation)

• Temperature (20⁰C and 35°C)

The design was performed as a fractional factorial design of resolution IV (anaerobic degradation) or resolution V (aerobic degradation). Both types included 16 experiments.

Generally, all experiments were performed according to plans defined by factorial designs. The general approach was to identify the effect of krill on degradation of organic waste - and whether krill addition possibly interact with other key parameters.

Example 3

Analytical methods

Gas volume measurement: The needle of a syringe was injected into the rubber septum of the glass bottle. The produced gas contained in the bottle would repress the syringe piston to a volume equilibrating at ambient pressure. The volume read at this equilibrium was the actual gas volume produced.

Gas composition analysis: Aliquots of 0.5 ml were withdrawn from the bottle through the septum, and separated on a CTR 1 double-column from Alltech. The chromatography was performed on a Perkin Elmer Autosystem equiped with Thermal Conductivity Detector (TCD) and Flame Ionization Detector (FID).

Colony forming units: 10 ml of the degrading mixture was withdrawn and serially diluted in distilled water to 10-8. Aliquots of 0.1 ml from dilutions at 10-7 and 10- 8 were plated onto Nutrient Broth Agar plates and incubated at 37°C. The plates were scored after two days.

Example 4

Confirmation and characterisation of the effect of krill addition

In the second experimental setup, the aim was to study any dose response of krill with respect to degradation activity, and to compare the effect of krill with salmon fillet. Salmon fillet has a relatively low level of endogenous enzymatic activities and a small endogenous microflora while having a content of protein, lipids, and fat that is comparable with that of krill.

The following factors were analyzed for 14 days: • Krill addition (0; 5%; 10%; 20%; 30%)

• Salmon fillet addition (0 and 10%)

• Temperature (2O⁰C and 35°C)

The design was performed as a multi-level full-factorial design. The anaerobic experiment included two replicates, making a total of 40 samples. Replicate samples were analysed only for gas volume productions. The aerobic design had no replicates, resulting in 20 samples altogether.

Gas production was measured at day 2, day 3, day 7, day 9 and day 14. Gas composition was measured at day 2 and day 14.

Example 5

Overview of the samples

Table 1

Survey of all samples in screening experiment under anaerobic conditions

Sample Starter number Krill Food Waste Hay Lime Culture Temperature

1 0 0 0 0 0 20

2 10 0 0 0 20 20

3 0 10 0 0 20 35

4 10 10 0 0 0 35

5 0 0 10 0 20 35

6 10 0 10 0 0 35

7 0 10 10 0 0 20

8 10 10 10 0 20 20

9 0 0 0 5 0 35

10 10 0 0 5 20 35

11 0 10 0 5 20 20

12 10 10 0 5 0 20

13 0 0 10 5 20 20

14 10 0 10 5 0 20

15 0 10 10 5 0 35

16 10 10 10 5 20 35 Table 2

Survey of all samples in screening experiment under aerobic conditions

Sample Food number KrIII Waste Hay Lime Temperature

1 0 0 0 0 35

2 10 0 0 0 20

3 0 10 0 0 20

4 10 10 0 0 35

5 0 0 10 0 20

6 10 0 10 0 35

7 0 10 10 0 35

8 10 10 10 0 20

9 0 0 0 5 20

10 10 0 0 5 35

11 0 10 0 5 35

12 10 10 0 5 20

13 0 0 10 5 35

14 10 0 10 5 20

15 0 10 10 5 20

16 10 10 10 5 35

Table 3

Survey of all samples in multi-level experiment including krill, salmon and temperature

Sample number Krill Salmon Temperature

1 0 0 20

2 5 0 20

3 10 0 20

4 20 0 20

5 30 0 20

6 0 10 20

7 5 10 20

8 10 10 20

9 20 10 20

10 30 10 20

11 0 0 35

12 5 0 35

13 10 0 35

14 20 0 35

15 30 0 35

16 0 10 35

17 5 10 35

18 10 10 35

19 20 10 35

20 30 10 35

Claims

1. A method of decomposing organic material, said method comprising a step of mixing active components derived from crustaceans with said organic material followed by incubation of said mixture.

2. A method according to claim 1, wherein the crustacean components are fully or partly derived from krill.

3. A method according to any one of claims 1-2, wherein the incubation is performed under essentially anaerobic conditions.

4. A method according to any one of claims 1-2, wherein the incubation is performed under essentially aerobic conditions.

5. A method of producing biogas, wherein said method comprises the process steps according to any one of claims 1-4.

6. A method of producing fertilizer, wherein said method comprises the process steps according to any one of claims 1-4.

7. A method of producing bioethanol, wherein said method comprises the process steps according to any one of claims 1-4.

8. A method according to claim 5, wherein said method comprises the step of collecting a fraction of the resulting biogas and using said fraction of biogas to heat the incubation mixture.

9. A method according to any one of claims 1-8, wherein said method comprises addition of one or more additives.

10. A method according to claim 9, wherein the additives are selected from the group consisting of: digestive enzymes, microorganisms, minerals, nitrogen, phosphorus, fermentative sugars, waste food, hay, straw, acidic compounds, and basic compounds.

11. A composition obtainable by a method according to any one of claims 1-10.

12. A composition according to claim 11 which is a fertilizer composition.

13. Use of active components derived from crustaceans for catalyzing decomposition of organic material.