HUP1000422A2 - Gasifiable biomass - Google Patents

Description

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GASIFYABLE BIOMASS

The invention relates to gasifiable biomass for a biogas plant.

Biogas is a gas mixture formed as a result of the anaerobic decomposition of organic matter in biomass by microorganisms, which mainly contains methane. This microbiological process consists of two main parts, fermentation and methane formation. A specific carbon-nitrogen ratio is required for proper fermentation, optimally 1:20-1:30.

As is known, one way to dispose of waste poultry feathers is to compost them, but feathers decompose very slowly in compost. Another disadvantage of feather composting is the large ammonia and hydrogen sulfide emissions, which inevitably pollute the atmosphere. One of the means of reducing odorous gases and harmful emissions is fermentation carried out in a closed system. Gasification of organic materials and their combustion in a gas engine is the most effective means of recovering the energy contained in organic materials, including poultry feathers. Unlike composting, the process produces recyclable energy. Keratin, which is the material of feathers, is a water-insoluble protein that is very resistant to enzymes with proteolytic activity. Keratin proteins are connected by disulfide bridges, which contribute to the very high structural stability of feathers. Several methods are possible to cleave these disulfide bridges. Among these, we can mention, for example, chemical treatments. Another possible disposal technique is heat treatment. At high temperatures and under pressure, a significant part of the sulfur bridges in keratin break down, without producing harmful by-products. After heat treatment, the protein loses its stable structure, making it accessible to proteases produced by microbes. Extracellular proteases can be used to remove keratin-containing contaminants. Currently, several microorganisms that produce extracellular proteases are known. Several proteases produced by bacteria and fungi are used in industry. Their use has several advantages, including their low cost, high efficiency of operation, and most importantly, the fact that they do not pollute the environment. What is described in the literature

BUDAPATENT/10.677 microorganisms that produce enzymes capable of breaking down keratin, however, most of these have a low keratin-breaking ability, require complex media for their maintenance, and are possibly human pathogens, so their applicability on a commercial scale is limited.

The possibility of digesting poultry feathers with microorganisms is known, for example, with the help of the keratin-degrading bacterium Bacillus licheniformis, which was reported by Williams et al. in 1990 in Appl.Env.Microbiol. 56(6), pp. 1509-1515. A further related article is, for example, Mézes et al.: “Investigation of the digestibility of poultry feathers for biogas utilization”, which was published in the Special Issue of Agrártudományi Közlemények 2007/26.

In addition to the fact that the use of poultry feathers for biogas production solves the processing of poultry feathers as waste, poultry feathers with a high crude protein content are also suitable for improving the carbon-nitrogen ratio of high-carbon agricultural waste raw materials used for biogas production, such as liquid manure, plant waste and by-products.

Based on our understanding, the aim of our invention is to provide gasifiable biomass for biogas plants, by means of which the biomass containing high-carbon agricultural waste raw materials also contains a certain proportion of poultry litter pretreated with the bacterium Bacillus licheniformis.

Our invention is accordingly a gasifiable biomass for a biogas plant, where the biomass contains at least the following raw materials: water, preferably process water, organic agricultural waste raw materials, glycerol and poultry feathers pretreated with the Bacillus licheniformis KK1 bacterial strain, where the weight ratio of the pretreated poultry feathers with respect to the total raw material quantity is 0.5-5%.

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The water used is usually process water, which is a raw material with a low dry matter content and is necessary to adjust the moisture content required by the technology. Its sulfur content is negligible.

Glycerin is the most excellent carbon source. It can be obtained, for example, as a by-product of biodiesel production and esterification. It has practically no nitrogen content, therefore it effectively improves the unfavorable carbon-nitrogen ratio. Its sulfur content is minimal.

In a preferred embodiment, the weight ratio of pretreated poultry to the total raw material is 1-2%, in particular about 1-1.2%. The proportion of poultry feathers is primarily limited by the sulfur content. In the case of a poultry feather proportion of about 1%, no separate desulfurization is necessary.

In a further preferred embodiment, the organic agricultural waste raw materials comprise the following raw materials or at least one of them: corn silage, cattle slurry, cattle manure, meat juice, other green material.

Corn silage is primarily a winter crop, but is actually used year-round. It has an excellent carbon-to-nitrogen ratio of 1:25 - 1:30.

Cattle slurry is produced by wet removal of manure. It has a carbon-nitrogen ratio of 1:15-1:20 and a low sulfur content.

Cattle manure is characterized by a higher dry matter and sulfur content. It comes from littered cattle farming and is suitable for quantitative buffering.

Meat broth is a by-product of protein processing plants, with a carbon-nitrogen ratio of 1:5, which is very unfavorable, and therefore can only be used in conjunction with a significant carbon source. However, it is one of the best gas-yielding raw materials. Its sulfur content is high. Meat broth must be fed directly to the fermenter, as its hydrolysis occurs quickly and therefore it begins to gasify practically during mixing.

Other green matter is a seasonal raw material, some kind of field green plant, such as green peas or other legumes. Its larger intake should be avoided due to the unfavorable carbon-nitrogen ratio, which is 1:10. At the same time, it is an easily digestible raw material, so it can be well utilized when paired with a carbon source.

BUDAPEST/ 10,677

In a further preferred embodiment, the biomass also contains at least one of the following additional raw materials: fermentation broth, separated material, poultry wastewater, whey.

The separated material is the solid phase remaining during the physical separation of the fermented ferment, the organic matter content of which is still very significant. Its return to the beginning of the process is justified because of the carbon source that is still capable of degassing. The carbon-nitrogen ratio of the separated material is excellent, thanks to the fact that the nitrogen forms tend to the liquid phase. For this reason, it can also be used to improve the ratio, but it is also a good reserve in case of temporary raw material shortages. The sulfur content is basically a function of the recipe, practically corresponding to its average value, but in any case its reduced value, since sulfur is released in several ways during the process.

Poultry wastewater is the process water generated from slaughterhouse washing.

The carbon-nitrogen ratio of whey is excellent for biogas production. Its dry matter content is 20%, and its sulfur content is below 3%. Its significance is primarily in the field of pH adjustment. It specifically helps the acidogenic phase, but it is also an excellent additive when ammonia release due to rising pH needs to be prevented. By adding it, the risk of foaming can be reduced.

Our invention also provides a method for pre-treating poultry feathers with Bacillus licheniformis KK1 bacterial strain, by heating the 1:6 - 1:2 poultry feather - water mixture to at least 60 C° for at least 0.5 hour, then maintaining it at this temperature for at least 15 minutes, then after at least 2 hours the temperature of the system is reduced to below 50 C°, preferably to 42 ± 2 C°, and inoculated with the bacteria at a 0.5-3% bacteria - poultry feather weight ratio, and from the beginning of the decomposition process the temperature is set to 42 ± 2 C°, which is suitable for the life conditions of the bacteria, and is maintained at this level until the end of the decomposition process, while the pH of the system is measured and set to a value between 6.5-7.5, preferably 6.7-7.3.

In a preferred method, a mixture of poultry feathers and water in a weight ratio of about 1:2.5-3.5 is heated to 70 ± 5 C° for approximately 4-6, preferably 5 hours, then held at this temperature for preferably 1 hour, then the temperature of the system is reduced to 42 - 44 C° for approximately 12 hours, preferably 12 hours, and inoculated with the bacteria at a weight ratio of about 1-1.2% bacteria to poultry feathers,

BUDAPATENT/ 10.677 and from the beginning of the decomposition process, the temperature is set to 42 ±2 C°, which is suitable for the living conditions of the bacteria, and is maintained at this temperature until the end of the decomposition process, while the pH of the system is measured and set to a value between 6.5 - 7.5, preferably 6.8 - 7.2.

Our invention is described in more detail in connection with exemplary embodiments.

Many experiments were conducted to produce gasifiable biomass according to the invention, which yielded good results. In these experiments, the composition ranged from 25-45% by weight of process water, 50-65% by weight of organic agricultural waste raw materials, 0.5-3% by weight of glycerin, and 1-5% by weight of pretreated poultry feathers. Of the organic agricultural waste raw materials used, corn silage was 3-30% by weight, cattle slurry was 15-35% by weight, and cattle manure was 3-10% by weight. Some of the experimental recipes are described in more detail below.

Example: An exemplary recipe for gasifiable biomass according to the invention

Raw material: Quantity: Process water Corn silo 30%, 3%, Separated material Poultry wastewater Whey 0.7%, 0.5%, 7%,

Cattle slurry 30%,

Glycerin 0.5%, Cattle manure Meat broth 7%, 11%, Other green matter Fermented juice 2.3%, 7%, or 6%, or 3%, Pre-treated poultry feathers 1%, or 2%, or 5%, total: 100%

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• · · · .example: A further exemplary recipe for gasifiable biomass according to the invention

Raw material: Quantity:

Process water 30%,

Corn silage 19%,

Separated material 4%,

Whey 6%,

Cattle slurry25%,

Glycerin 2%,

Cattle manure 6%,

Meat broth 5%,

Green peas 1%,

Pretreated poultry feathers 2%.

Total: 100% .example: A further exemplary recipe for gasifiable biomass according to the invention

Raw material: Quantity: Process water Corn silo 30%, 17%, Separated material Whey 4%, 6%,

Cattle slurry 30%,

Glycerin 2%, Cattle manure Meat broth 4%, 4%, Green peas Pre-treated poultry feathers 1%, 2%. total: 100%

BUDAPATENT/10.677 .example: A further exemplary recipe for gasifiable biomass according to the invention

Raw material: Quantity: Process water Corn silo 30%, 15%, Separated material Whey 4%, 7%,

Cattle slurry 30%,

Glycerin 2%, Cattle manure Meat broth 4%, 3%, Green peas 1%, Pre-treated poultry feathers 2%. total: 100%

Example 5: A further exemplary recipe for gasifiable biomass according to the invention

Raw material: Quantity: Process water Corn silo 38%, 20%, Separated material Whey 3%, 5%,

Cattle slurry 18%,

Glycerin 3%, Cattle manure Meat broth 4%, 6%, Green peas 1%, Pre-treated poultry feathers 2%. Total: 100%

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Of the listed materials, separated material as a non-gasified carbon source, poultry wastewater, whey, and fermented juice should only be used if they are readily available.

The poultry feathers in the recipes can be pretreated as follows, for example. The chopped poultry feathers are mixed with water in a ratio of approximately 1:3 by filling a 6 m ³ tank with 3 m ³ of water and 11 (~1.1-1.5 m ³ ) of poultry feathers and stirring, then the mixture is heated to a temperature of about 70°C for about 4-6, preferably 5 hours, and then held at this temperature for about 1-1.5 hours. Then, after about 12 hours, the temperature of the system is reduced to about 42 - 44 C°, where it is inoculated with a culture of the Bacillus licheniformis KK1 bacterial strain in a ratio of about 1-1.2% bacteria to poultry feathers. From the beginning of the decomposition process, the temperature is maintained at 42°C ±2°C, which is suitable for the living conditions of the bacteria, until the end of the decomposition process, while the pH of the system is measured and adjusted to a value between 6.7 and 7.3. After the poultry manure-water ratio is established, the pH of the system is usually reduced to approx. 6.5. As a result of inoculation with a neutral pH bacterial culture, the pH increases slightly, but does not reach the optimal value of 6.8-7.2, therefore, lime milk is added to the system. As a result, a stage of around neutral pH can be reached, which is maintained until the final stage of the process. In the final stage of fermentation, due to the decreasing activity, the pH value increases slightly.

The experimental results with the listed recipe compositions showed that the carbon-nitrogen ratio was adequate, and the following increase in gas yield was achieved: in the case of a 2% poultry feather ratio, the gas yield increased by 1.4%, while in the case of a 1% poultry feather ratio, it increased by 1.22%. There was no significant difference in the methane and carbon dioxide concentrations of the biogas in the case of the treatments with a 2% or 1% poultry feather ratio. The maximum amount of feathers that can be introduced into biogas fermenters can be limited based on the H2S produced from it; At a 2% mixing ratio, an average of 345 ppm hydrogen sulfide was detected, which is an acceptable amount with the use of a sulfur cleaning process. In the case of a 1% mixing ratio, the hydrogen sulfide was already below 300 ppm

BUDAPATENT/10.677 production, which does not require a desulfurization process. Accordingly, this ratio can be recommended for use in biogas plants where the technology does not include a separate desulfurization process.

The parameters of the biogas composition were continuously measured using a computer-controlled gas analyzer in both the mesophilic and thermophilic fermenters. When examining the CO2 and CH4 concentrations of the biogas produced in the plant, it can be observed that methane took on values between 58-68% and carbon dioxide between 29-41%. No significant difference was observed between the gas quality of the mesophilic and thermophilic fermenters.

In addition to measuring the carbon dioxide and methane content, the hydrogen sulfide and ammonia content were also continuously monitored. The hydrogen sulfide ratio in the biogas - due to its corrosive effect - must be reduced if necessary. The ammonia ratio shows the degree of outgassing of the N content in the produced biogas. In contrast to the hydrogen sulfide content, no significant change could be detected in the ammonia content, i.e. even with a mixing ratio of 2%, the difference was not significant.

Our invention can be implemented in a wide variety of ways within the scope of protection, even other than the examples listed, therefore the scope of protection cannot be interpreted as limited to the examples.

With the help of the invention, in addition to improving the carbon-nitrogen ratio of gasifiable biomass, the available gas yield will be higher, and in addition, the use of waste poultry feathers will also be solved. It is also worth mentioning that pretreated poultry feathers can potentially be used as a biogas feedstock because in this physical state they neither endanger the heating pipes nor tend to float.

BUDAPEST/10.677

Claims (6)

10 : . ·· :.. ·..: • ··· ·· ·· ·· ·· Patent claims: 1. Gasifiable biomass for a biogas plant, characterized in that the biomass contains at least the following raw materials: water, preferably process water, organic agricultural waste raw materials, glycerol and poultry feathers pretreated with Bacillus licheniformis KK1 bacterial strain, where the weight ratio of the pretreated poultry feathers with respect to the total raw material quantity is 0.5-5%. 2. Biomass according to claim 1, characterized in that the weight ratio of the pretreated poultry feathers, relative to the total amount of raw material, is 1 - 2%, in particular 1 - 1.2%. 3. Biomass according to claim 1 or 2, characterized in that the organic agricultural waste raw materials comprise the following raw materials or at least one of them: corn silage, cattle slurry, cattle manure, meat juice, other green material. 4. Biomass according to any one of claims 1 to 3, characterized in that it also contains at least one of the following raw materials: fermentation broth, separated material, poultry wastewater, whey. 5. Method for pre-treating poultry feathers with Bacillus licheniformis KK1 bacterial strain, characterized in that the 1:6 - 1:2 poultry feather - water mixture is heated to at least 60 C° in at least 0.5 hour, then maintained at this temperature for at least 15 minutes, then after at least 2 hours the temperature of the system is reduced to below 50 C°, preferably to 42 ± 2 C°, and the bacteria are inoculated at a 0.5-3% bacteria - poultry feather weight ratio, and from the beginning of the decomposition process the temperature is adjusted to 42 ± 2 C°, which is suitable for the life conditions of the bacteria, and is maintained at this level until the end of the decomposition process, while the pH of the system is measured and adjusted to a value between 6.5-7.5, preferably 6.7-7.3. BUDAPEST/ 10,677 6. The method according to claim 5, characterized in that a 1:2.5-3.5 weight ratio poultry feather - water mixture is heated to 70 ± 5 C° in 4-6 hours, then maintained at this temperature, preferably for 1-1.5 hours, then the temperature of the system is reduced to 42 - 44 C°, preferably in 12 hours, and the bacteria are inoculated at a 1-1.2% bacteria - poultry feather weight ratio, and from the beginning of the decomposition process the temperature is set to 42 ± 2 C°, which is suitable for the life conditions of the bacteria, and is maintained at this temperature until the end of the decomposition process, while the pH of the system is measured and set to a value between 6.5-7.5, preferably 6.8-7.2. BUDAPEST/10.677