Treatment of organic waste

Abstract

The present invention relates to a method for treating organic waste, comprising the step of treating organic waste with a microbial composition comprising the following microbial species: Niallia sp., Stenotrophomonas sp., and Staphylococcus sp. Wherein the treatment step is carried out in an aerobic environment and under agitation to convert organic waste into organic fertilizer.

Description

Field of the Invention

[0001] The present invention relates to waste management. In particular, the present invention relates to the treatment of organic waste, and more particularly to rapid thermophilic treatment of organic waste. The present invention also relates to an organic fertilizer derived from the treatment of organic waste. Background of the Invention

[0003] Organic waste such as food waste and agricultural waste is produced in large quantities, and an increasing trend of waste generation is observed. Waste management is now becoming a huge problem. Most organic waste is either incinerated or thrown into landfills or oceans. Over time, the organic waste in landfills undergoes biodegradation and produces a large amount of greenhouse gases such as methane, thereby causing climate temperature to rise (greenhouse effect). Harmful substances such as antibiotics, chemicals and pathogens may leach from organic waste and enter soil and groundwater along with the decomposition of organic waste.

[0004] Finding ways to properly manage organic waste is of vital importance. Attempts have been made to convert or recycle organic waste into useful goods or products, although this constitutes only a small fraction of the organic waste generated. Due to the recent increase in public awareness of waste management, activities involving the recycling of organic waste have gradually increased, however, this remains unsatisfactory due to various limitations in the available methods for recycling organic waste.

[0005] An example of recycling organic waste is converting organic waste into energy via digestion, wherein during the digestion process, the waste is subjected to an oxygen-deficient environment and decomposes, producing an alternative energy source called biogas. Sludge is a byproduct of biogas production and can be used for fertilization and soil improvement, and inactivates pathogens in organic waste. Nevertheless, biogas production usually requires high capital costs and long processing times, and not all types of organic waste can be treated in this way. Other alternative uses of organic waste include fish farming, production of algae for human and animal consumption, and production of aquatic plants for animal feed supplements. Organic waste is also often composted until it becomes a nutrient-rich fertilizer or soil conditioner and soil improver.

[0006] Composting converts organic waste into harmless and value-added products through microbial processes. Composting is usually carried out naturally by using naturally occurring microorganisms, and usually does not produce harmful by-products, and therefore usually does not require post-process treatment. However, natural composting can easily take up to several months and even years to mature, and usually produces a product with a relatively low nitrogen, phosphorus and potassium (NPK) content (usually less than 1:1:1). Organic fertilizers with low NPK content are less useful and less valuable.

[0007] There are currently a variety of biological treatments that can be used to increase the speed of composting. One of these treatments is disclosed in Chinese Patent No. CN112760274B. Aerobic composting of solid organic waste using a liquid or solid preparation containing Pantoea sp. requires about 10 days or more to mature the waste. Japanese Patent No. JP 5445821 B2 discloses the use of a microbial composition containing microorganisms selected from Paenibacillus sp., Bacillus sp. and Brevibacterium sp. in the decomposition of organic waste, with a relatively short treatment time of 3 to 5 days. In PCT Publication No. WO 2011 / 119112 A1, a method for treating organic waste is disclosed, comprising the step of contacting the organic waste with at least three of a Bacillus sp. microorganism, a Pseudomonas sp. microorganism, a Bifidobacterium sp. microorganism, and a Lactobacillus sp. microorganism under conditions that convert the organic waste at least partially into organic fertilizer. However, this process still requires at least 24 hours to mature.

[0008] Although available biological treatments require a relatively shorter period of time to mature compared to natural composting, their efficiency is still unsatisfactory considering the huge amount of organic waste generated. Therefore, there is a need to provide an efficient, simple, cost-effective and environmentally friendly method for treating organic waste. SUMMARY OF THE INVENTION

[0010] According to one aspect of the present invention, there is provided a method for treating organic waste, comprising the following steps: treating the organic waste with a microbial composition comprising the following microbial species: Niallia sp., Stenotrophomonas sp. and Staphylococcus sp., wherein the treating step is carried out in an aerobic environment and under stirring to convert the organic waste into organic fertilizer.

[0011] Preferably, the initial moisture content of the organic waste is controlled at 25 wt % to 70 wt %, preferably 30 wt % to 65 wt %, and more preferably about 45 wt %.

[0012] Preferably, the Niallia species are Niallia circulans, Niallia endozanthoxylica, Niallia nealsonii, Niallia taxi and Niallia oryzisdi, the Stenotrophomonas species are Stenotrophomonas maltophilia, Stenotrophomonas rhizophili, Stenotrophomonas africana and Stenotrophomonasacidaminiphlia, and the Staphylococcus species are Staphylococcus haemolyticus, Staphylococcus aureus, Staphylococcus intermedius, Staphylococcus epidermidis epidermidis and Staphylococcus simulan.

[0013] Preferably, the weight ratio of the microbial composition to the organic waste is 1:1000 to 2:1000.

[0014] Preferably, the treating step is carried out at a temperature of 60°C to 85°C.

[0015] Preferably, the treating step is performed using intermittent aeration, and more preferably, each cycle of aeration is performed for 5 to 45 minutes and paused for 5 to 45 minutes.

[0016] Preferably, the stirring speed is 3 rpm to 10 rpm.

[0017] Preferably, prior to the treating step, the method further comprises the step of reducing the size of the organic waste.

[0018] Preferably, the microbial composition comprises 1×10 10 cfu / g powder up to 15×10 10 More preferably, the microbial composition comprises a bulking agent selected from rice bran, ash, water, skimmed milk powder, corn meal or any combination thereof.

[0019] Alternatively, the microbial composition is a solution comprising 5 vol% to 50 vol% of microorganisms.

[0020] Preferably, the treating step is carried out for 12 hours or less.

[0021] The preferred embodiments of the present invention consist of the novel features and combinations of parts fully described and illustrated in the accompanying drawings and particularly pointed out in the appended claims; it should be understood that various changes in the details may be made by those skilled in the art without departing from the scope of the invention or sacrificing any advantages of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, the present invention will be described according to the preferred embodiments of the present invention and by reference to the attached description and drawings. However, it should be understood that the description is limited to the preferred embodiments of the present invention and the drawings only for the convenience of discussing the present invention, and it is envisaged that various modifications can be designed by those skilled in the art without departing from the scope of the attached claims.

[0024] The present invention relates to waste management. In particular, the present invention relates to the treatment of organic waste, and more particularly, to the rapid high temperature treatment of organic waste. The present invention also relates to an organic fertilizer derived from the treatment of organic waste.

[0025] Organic waste

[0026] As used herein, the term "organic waste" refers to any biodegradable carbonaceous material, and comes from plants or animals. Organic waste includes, but is not limited to, agricultural waste, food waste, organic refuse, mill effluent, municipal waste, sewage, sludge, animal waste, industrial waste or any combination thereof. Examples of agricultural waste include, but are not limited to, empty fruit bunches (EFB), palm decanter cake slurry, olive shells, corn cobs, coffee bean shells, rice husks, straw, waste mushroom compost, palm leaves, palm trunks, palm kernel shells, palm fiber, farm effluent, slaughterhouse waste, flower cuttings, waste flower compost, straw, fruit waste, vegetable waste, etc. Examples of animal waste include, but are not limited to, dead animals, animal feathers, animal parts (such as animal intestines) and animal feces, such as poultry feces, cow feces, goat feces, horse feces, sheep feces and pig feces.

[0027] One or more types of organic waste can be used. For example, EFB can be used with chicken manure, or food waste can be used with rice husks. Other exemplary combinations of organic waste include, but are not limited to, a combination of chicken manure with sawdust, a combination of chicken manure with chicken feathers, a combination of EFB with chicken manure, and a combination of EFB with palm oil mill effluent (POME).

[0028] Microbial composition

[0029] Microorganisms useful in the disclosed methods are those capable of degrading carbon compounds or fixing nitrogen compounds. Advantageously, mixed cultures of microorganisms are used to obtain a broad spectrum of degradation or fixation.

[0030] In one embodiment, a composition is provided that includes at least one microorganism from each of the following microbial species: Niella species, Stenotrophomonas species, and Staphylococcus species.

[0031] The microorganism of the genus Nierella is preferably selected from the group consisting of Nierella circulans, Nierella endophytica of Zanthoxylum, Nierella nelsonii, Nierella yew and Nierella oryzae. The microorganism of the genus Stenotrophomonas is preferably selected from the group consisting of Stenotrophomonas maltophilia, Stenotrophomonas rhizophila, Stenotrophomonas africana and Stenotrophomonas microacidophilus. The microorganism of the genus Staphylococcus is preferably selected from the group consisting of Staphylococcus haemolyticus, Staphylococcus aureus, Staphylococcus intermedius, Staphylococcus epidermidis and Staphylococcus mimicus.

[0032] Each of the genus Niella, Stenotrophomonas, and Staphylococcus may contain one, two, three, four or more microorganisms from the same species.

[0033] The choice of microorganism may depend on the type of organic waste to be treated.

[0034] The microbial composition may be in the form of a solution, although a powder form is preferred for better stability of the microorganisms. The microbial solution is preferably kept cool at a temperature of 0°C to 10°C for long-term storage to ensure that there is a sufficient amount of the microorganisms in their viable state. However, the microbial powder can be stored at room temperature as long as it is away from sunlight and rain.

[0035] The microbial content of the microbial solution can comprise about 5vol% to about 50vol% of the microorganisms in the microbial culture, about 10vol% to about 50vol% of the microorganisms, about 15vol% to about 50vol% of the microorganisms, about 20vol% to about 50vol% of the microorganisms, about 25vol% to about 50vol% of the microorganisms, about 30vol% to about 50vol% of the microorganisms, about 35vol% to about 50vol% of the microorganisms, about 40vol% to about 50vol% of the microorganisms, about 45vol% to about 50vol% of the microorganisms, about 5vol% to about 40vol% of the microorganisms, about 5vol% to about 30vol% of the microorganisms, about 5vol% to about 20vol% of the microorganisms or about 5vol% to about 15vol% of the microorganisms. In a preferred embodiment, the microbial content of the microbial solution comprises about 10vol% to about 20vol%.

[0036] Additives for enhancing the effectiveness and efficiency of waste treatment, such as biocatalysts, buffers, nutrients and surfactants, generally do not need to be added to the microbial composition.

[0037] Microbial powder comprises the blend of microorganism and filler or carrier.Filler or carrier include but are not limited to ash, lentil flour, soy flour, sugarcane pulp, fish meal, corn meal, rice bran, wheat bran, skimmed milk powder, charcoal powder or its any combination.Other suitable fillers can be used, as long as this filler can produce powdery mixture with microorganism, and do not affect the viability of microorganism simultaneously.Preferably, filler is from natural source and does not release toxic gas or compound.One or more types of fillers can be used as filler or carrier.For example, filler can comprise one, two, three, four, five, six or more types of fillers.

[0038] The microbial content of the microbial powder may include the following amounts of microorganisms: about 1×10 10 cfu / g powder is about 15×1010 cfu / g powder, about 1×10 10 cfu / g powder is about 14×10 10 cfu / g powder, about 1×10 10 cfu / g powder is about 13×10 10 cfu / g powder, about 1×10 10 cfu / g powder is about 12×10 10 cfu / g powder, about 1×10 10 cfu / g powder is about 11×10 10 cfu / g powder, about 1×10 10 cfu / g powder is about 10×10 10 cfu / g powder, about 1×10 10 cfu / g powder is about 9×10 10 cfu / g powder, about 1×10 10 cfu / g powder is about 8×10 10 cfu / g powder, about 1×10 10 cfu / g powder is about 7×10 10 cfu / g powder, about 1×10 10 cfu / g powder is about 6×10 10 cfu / g powder, about 1×10 10 cfu / g powder is about 5×10 10 cfu / g powder, about 1×10 10 cfu / g powder is about 4×10 10 cfu / g powder, about 1×10 10 cfu / g powder is about 3×10 10 cfu / g powder, about 1×10 10 cfu / g powder is about 2×10 10 cfu / g powder, about 2×10 10 cfu / g powder is about 15×10 10 cfu / g powder, about 3×10 10 cfu / g powder is about 15×10 10 cfu / g powder, about 4×10 10 cfu / g powder is about 15×10 10 cfu / g powder, about 5×10 10 cfu / g powder is about 15×10 10 cfu / g powder, about 6×10 10 cfu / g powder is about 15×10 10 cfu / g powder, about 7×10 10 cfu / g powder is about 15×1010 cfu / g powder, about 8×10 10 cfu / g powder is about 15×10 10 cfu / g powder, about 9×10 10 cfu / g powder is about 15×10 10 cfu / g powder, about 10×10 10 cfu / g powder is about 15×10 10 cfu / g powder, about 11×10 10 cfu / g powder is about 15×10 10 cfu / g powder, about 12×10 10 cfu / g powder is about 15×10 10 cfu / g powder, about 13×10 10 cfu / g powder is about 15×10 10 cfu / g powder or about 14×10 10 cfu / g powder is about 15×10 10 cfu / g powder.

[0039] Pretreatment of organic waste

[0040] Prior to treatment, the organic waste may need to be pre-treated. For example, the particle size of the solid organic waste may be reduced to facilitate the treatment process. Typically, the particle size of the organic waste may be reduced to about 1 mm to about 20 mm, and preferably about 5 mm to about 10 mm.

[0041] The moisture content of organic waste varies greatly from source to source, and it determines the availability of waste that is likely to be converted into organic fertilizer. In this regard, the initial moisture content of organic waste can be controlled within or adjusted to the following range: for example, about 25wt% to about 70wt%, about 25wt% to about 60wt%, about 25wt% to about 50wt%, about 25wt% to about 40wt%, about 25wt% to about 35wt%, about 25wt% to about 30wt%, about 30wt% to about 70wt%, about 40wt% to about 70wt%, about 50wt% to about 70wt%, about 60wt% to about 70wt%, about 65wt% to about 70wt%, about 30wt% to about 65wt%, about 35wt% to about 60wt%, about 40wt% to about 55wt% or about 45wt% to about 50wt%. Preferably, the initial moisture content of organic waste is about 30wt% to about 65wt%, and more preferably about 45wt%. The initial moisture content of the organic waste can be controlled or adjusted by any means known to those skilled in the art.

[0042] Organic waste can be optionally combined with other additives or nutrients to enhance the treatment process and / or increase the nutrient level of the organic fertilizer produced by the treatment process. Such additives can be, for example, carbon sources such as ash, sawdust, dry leaves, wood shavings, rice straw, waste paper, etc.

[0043] pH control is usually not required and the treatment process can be carried out at the pH of the organic waste used.

[0044] Treatment of organic waste

[0045] By inoculating organic waste with the microbial composition, the organic waste is treated with the microbial composition, wherein the treatment is carried out under aerobic environment and stirring to convert the organic waste into organic fertilizer. Usually stir gently with about 3rpm to 10rpm (e.g. 5rpm). Once the treatment begins, that is, when the organic waste contacts with the microbial composition, it is not necessary to monitor or control the moisture content of the organic waste.

[0046] Contact of the organic waste with the microbial composition results in degradation or conversion of compounds contained in the organic waste, thereby neutralizing odorous compounds contained therein and rendering the organic waste odorless, or results in conversion of carbon compounds or nitrogen fixation to increase the nutrient level of the organic waste.

[0047] Preferably, the weight ratio of the microbial composition to the organic waste is at least 1: 1000. Higher weight ratios of the microbial composition to the organic waste may be used to improve the efficiency of the treatment process, for example, 1.1: 1000, 1.2: 1000, 1.3: 1000, 1.4: 1000, 1.5: 1000, 1.6: 1000, 1.7: 1000, 1.8: 1000, 1.9: 1000, 2: 1000, 2.5: 1000, 3: 1000, 3.5: 1000, 4: 1000, 4.5: 1000 or 5: 1000.

[0048] The treatment is carried out at a temperature of, for example, about 60°C to about 85°C, about 65°C to about 85°C, about 70°C to about 85°C, about 75°C to about 85°C, about 80°C to about 85°C. During the treatment process in this temperature range, unwanted microorganisms such as Shigella sp. microorganisms, Salmonella sp. and E. coli will be removed or destroyed. Typically, the treatment process will generate a certain degree of heat, usually at a temperature of about 73°C, and therefore, temperature monitoring may not be required thereafter.

[0049] Required treatment time can depend on factors such as initial NPK level and / or C:N ratio of organic waste to be treated, type and concentration of microorganism used and treatment conditions used in this process.Usually, the organic waste is treated with microbial composition for about 12 hours or shorter time period.For example, the treatment period can be about 5 hours to about 12 hours, about 6 hours to about 12 hours, about 7 hours to about 12 hours, about 8 hours to about 12 hours, about 9 hours to about 12 hours, about 10 hours to about 12 hours, about 11 hours to about 12 hours, about 5 hours to about 11 hours, about 5 hours to about 10 hours, about 5 hours to about 9 hours, about 5 hours to about 8 hours, about 5 hours to about 7 hours or about 5 hours to about 6 hours.Because the treatment period only continues 12 hours or shorter, therefore do not need dosing usually.

[0050] Advantageously, within about 12 hours, an NPK content of about 1-5:1-5:1-7 and a C:N ratio of about 5:1 to about 30:1 can be achieved. Generally, a higher NPK content results in a more effective fertilizer because a smaller amount of fertilizer is required to promote plant growth than a fertilizer with a lower NPK content. Therefore, organic fertilizers with higher NPK contents are more cost-effective than organic fertilizers with lower NPK contents. A lower C:N ratio is preferred for use as a fertilizer to promote plant growth.

[0051] Preferably, the treatment is carried out under aeration. Aeration can be provided continuously or intermittently / periodically throughout the treatment process. Air can be pumped in for about 5 minutes to 45 minutes, for example, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes or 45 minutes, paused for about 5 minutes to 45 minutes, for example, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes or 45 minutes, and pumped in again for about 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes or 45 minutes.

[0052] After processing the organic waste, the processed organic waste product is cooled at room temperature, typically for 1 day to about 2 days, to produce an organic fertilizer product, which is then packaged.

[0053] An example of an apparatus that can be used to practice the treatment method of the present invention is as disclosed in PCT Publication No. WO 2011 / 119112 A1. Example

[0054] (A) Preparation of microbial composition

[0055] 1 L of nutrient broth was prepared by mixing 10 g glucose, 8 g yeast extract and 5 g sodium chloride. The nutrient broth was then inoculated with the selected microorganisms. The microbial composition in Table 1 was prepared. The inoculated nutrient broth was cultured at 35°C.

[0056] Table 1

[0057]

[0058] (B) Analytical methods

[0059] NPK content

[0060] Using the standard Kjeldahl method (APHA4500N org B) Determination of total nitrogen content in organic fertilizers. Organic fertilizers were digested with standard acid and then the phosphorus and potassium contents in organic fertilizers were determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES).

[0061] C:N Ratio

[0062] The organic carbon content is determined using the standard loss on ignition (LOI) method. A sample of organic waste or organic fertilizer is weighed and its initial weight is recorded. The sample is then placed in an oven at 350°C for 3 hours. The sample is then cooled, reweighed, and its final weight is recorded. The organic carbon content is determined as follows:

[0063] % organic carbon = (weight loss ÷ initial weight) x 100.

[0064] Using the standard Kjeldahl method (APHA4500N org B) Determine the nitrogen content.

[0065] The C:N ratio is then determined as follows:

[0066] C:N ratio = % organic carbon: % nitrogen.

[0067] (C) Preparation of organic fertilizer from raw chicken manure

[0068] Raw chicken manure and sawdust were mixed together. The initial moisture content of the organic waste mixture was adjusted to about 45 wt %. The microbial composition prepared as above was added to the mixture to obtain the samples in Table 2.

[0069] Table 2

[0070]

[0071] After the mixture and microorganisms were mixed, air was pumped in for 5 min, stopped for 40 min, and resumed for 5 min again to maintain an aerobic environment. The process was allowed to run for the time period shown in Table 2, and then cooled for 2 days. The NPK content and C:N ratio were determined using the above analytical methods. The analytical results of the treated samples are listed in Table 3.

[0072] Table 3

[0073] sample 1 2 3 N (wt%) 1.5 1.4 1.1 P (wt%) 1.9 5.7 5.6 K(wt%) 1.6 2.0 1.2 C:N ratio (before treatment) 45 45 45 C:N ratio (after treatment) 16 17 20 odor No odor Smell No odor texture good not good good

[0074] As can be seen from Table 3, all treated samples contained reasonably high NPK content / content, while the C:N ratio was significantly reduced. However, the odor and texture quality of Sample 2 were not satisfactory at a treatment time of 12 hours. A longer period of time (Sample 1, 24 hours) was required to eliminate the malodor of the organic waste and achieve the desired texture. On the other hand, Sample 3 using the microbial composition of the present invention was able to achieve high NPK content, reduce the C:N ratio, eliminate malodor and achieve the desired texture within a 12-hour treatment period.

[0075] The present disclosure includes the contents contained in the appended claims and the contents of the foregoing description. Although the present invention has been described in some detail in its preferred form, it should be understood that the disclosure of the preferred form is only by way of example, and many changes may be made to the details of the structure and the combination and arrangement of parts without departing from the scope of the present invention.

Claims

1. A method for treating organic waste, comprising the following steps: treating the organic waste with a microbial composition comprising at least one microorganism from each of the following microbial species: Niallia sp., Stenotrophomonas sp., and Staphylococcus sp., The treating step is carried out in an aerobic environment and under stirring to convert the organic waste into organic fertilizer.

2. The method according to claim 1, wherein the initial moisture content of the organic waste is controlled at 25wt% to 70wt%.

3. The method according to claim 2, wherein the initial moisture content of the organic waste is controlled at 30 wt% to 65 wt%.

4. The method according to any one of claims 1 to 3, wherein the Niallia species is Niallia circulans, Niallia endozanthoxylica, Niallia nealsonii, Niallia taxi and Niallia oryzisdi.

5. The method according to any one of claims 1 to 4, wherein the Stenotrophomonas species is Stenotrophomonas maltophilia, Stenotrophomonas rhizophilia, Stenotrophomonas africana and Stenotrophomonas acidaminiphlia.

6. The method according to any one of claims 1 to 5, wherein the Staphylococcus species is Staphylococcus haemolyticus, Staphylococcus aureus, Staphylococcus intermedius, Staphylococcus epidermidis and Staphylococcus simulans.

7. The method according to any one of claims 1 to 6, wherein the weight ratio of the microbial composition to the organic waste is 1:1000.

8. The method according to any one of claims 1 to 7, wherein the treating step is performed at a temperature of 60°C to 85°C.

9. The method according to any one of claims 1 to 8, wherein the treating step is performed using intermittent aeration.

10. The method of claim 9, wherein each cycle of aeration is performed for 5 to 45 minutes and paused for 5 to 45 minutes.

11. The method according to any one of claims 1 to 10, wherein: The stirring speed is 3 rpm to 10 rpm.

12. The method according to any one of claims 1 to 11, further comprising the step of reducing the size of the organic waste prior to the treating step.

13. The method according to any one of claims 1 to 12, wherein the microbial composition is a powder.

14. The method according to claim 13, wherein the microbial composition comprises 1×10 10 cfu / g powder up to 15×10 10 The amount of microorganisms in cfu / gram of powder.

15. The method according to claim 13 or 14, wherein the microbial composition further comprises a filler.

16. The method of claim 15, wherein the filler is selected from the group consisting of rice bran, ash, water, skim milk powder, corn meal, or any combination thereof.

17. The method according to any one of claims 1 to 16, wherein the microbial composition is a solution.

18. The method of claim 17, wherein the microbial composition comprises 5 vol% to 50 vol% microorganisms.

19. The method of any one of claims 1 to 18, wherein the treating step is performed for 12 hours or less.

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