HU203511B - Process for producing compost and biogas from agricultural side products and waste materias - Google Patents

Abstract

Compost and bio-gas are produced from available agricultural by-prods. and/or wastes, opt. added chemicals, milled peat and other additives. Required proportions are established by preliminary sampling chemical analysis, and composting requirements. In prepn., plant components are cut to 4-6mm length, all ingredients are homogenised and compacted. The solids content of the raw mix is adjusted to approx. 50% and its temp. is slowly raised to 60-62 deg.C. the operating temp. of a gastight fermenter to which it is fed. The fermentation is due to bacterial action. An inert atmos. is used during start up, but this changes to a fermentation gas cover during continuous operation. - The speed of the mix's progression in the fermentor is set to ensure 4-10 days fermentation time. The mix moves on an inclined plane, dilute manure, compost and opt. chemicals are added. The bacterial fermentation yields bio-gas, solid and liq. compost, which leave the fermentor respectively under gas tight conditions, or with the maintenance of a required internal pressure.

Description

The present invention relates to a process for the production of compost and biogas from agricultural by-products and agricultural waste.

Agricultural by-products and agricultural waste contain materials that can be recycled.

Devices and processes for producing compost and biogas from them are known.

Small-scale methods generally use slow fermentation for 45-80 days with high humidity and low dry matter content. During the low temperature process, undesirable microorganisms and weed seeds in the crude mixture are not destroyed, so adverse side effects may occur with the use of the resulting dilute compost. Ernő can read about this phenomenon in Ferenc Kovács: Animal Hygiene. [Agricultural Publishers, Budapest, 1975] and Kissné Dr. Eszter Quallich, The Biogas. [Agricultural Publisher, Budapest, 1983].

Similarly, in the case of large-scale fermentation, fermentation takes place at high humidity and with a low dry matter content of 5-6%. The material is transported by pump and fermentation is carried out at 30-35 ° C for 26-80 days. It is a disadvantage that these methods require the displacement, storage and storage of large amounts of water, that is, non-recoverable material.

It is also unfavorable that the resulting slurry compost is of limited environmental use, and the geographical conditions further limit the potential for use. The storage of high volume dilute compost also poses a problem. These difficulties are discussed by Kaltwasser, B.J., Biogas, Berlin, 1980, and Denminck, M.Nyns, E.J.-Palz, W., Biogas Plants in Europe, Solar Energy RD, Series E. Volume 6; 1984].

Some sub-tasks of this problem can be found in U.S. Patent Nos. 4,274,838 and 2,944,584, and in PCT Publication No. WO 82/02706. It presents devices for anaerobic fermentation of the first organic waste, production of the second biogas, and fermentation of the third organic matter.

The American concept was developed for the maturation of wastewater but is not suitable for composting. The German solution was also intended for biogas production. Both work by pumping large volumes of fluid. The subject of the PCT application is a device for the maturation of a liquid raw material, which is not suitable for processing agricultural by-products and waste materials. All three patents contain valuable ideas, but their application is limited and their cost-effectiveness is highly debatable.

A remarkable process is known for the fermentation of organic materials and for the production of biogas from Hungarian Patent Application No. 198 882. The slurry uses slurry as a raw material, but only biogas can be obtained as a useful product. The equipment described is not suitable for the production of compost. It is also unfavorable that the waste water discharged has an environmentally unacceptable composition.

The most advanced version of the known solutions can be found in Hungarian Patent Application No. 178,447, which discloses a semi-wet process and apparatus for fermentation of mixtures of animal fertilizers and agricultural and / or food waste. The concept positively combines aerobic digestion in the first three days with anaerobic digestion for a further 20-28 days, resulting in products that are complex to utilize, including both methane-containing biogas and organic manure.

The latter method eliminates the common disadvantages of the former, ie the need to store, move and store large amounts of water. However, the undoubted advantage also has its disadvantages. One of these is that the process is batchwise, so that the fermentation domes must be dismantled at the end of each fermentation stage, which complicates the handling of the device and the disassembly eliminates the anaerobic environment. It is a disadvantage that the temperature of 55-60 ° C formed from the 4th day of fermentation gradually decreases inside the treated material, and thus the conditions for the formation of biogas are rapidly deteriorating. Other types of methanogenic bacteria live in the thermophilic and others in the mesophilic zone. A further disadvantage is that aerobic fermentation according to the process also requires aeration, which is energy-intensive and thus cost-intensive. At the same time, hydrocarbons are evolved instead of methane.

There are also methods in which absorbent materials are added to wet manure rather than dilute, and the combination of these is aerobically matured into compost. Such processes are also limited in terms of utilization of raw materials and products. In addition, the absorbent additives absorb the resulting gases and thus no useful biogas is produced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a process that overcomes the disadvantages of the prior art processes and eliminates their disadvantages.

The goal is to ferment high quality compost from N / C starting materials in the range 10: 1-30: 1, pH 6-7.5, and biogas with a calorific value above 400 l / kg and with a heating value above 15,000 kJ / m ³ continuous production. Another aim is to protect the environment by continuously recovering waste and eliminating wastewater.

The inventive idea is based on the discovery that 50-80% by weight of the dry matter content of agricultural-21

EN 203 511 Β waste and agricultural waste. The plant parts - e.g. cereal straw, maize stalks, stalks and leaves of vegetables, etc., - with a dry matter content of more than 70%, up to a maximum length of 10 mm 5, in order to reduce the degradation time. Fresh manure and slurry compost should be added as a vaccine to rapidly start fermentation, to inject sufficient fermentation and methanogenic microorganisms. Fast, efficient fermentation can be achieved within a tight temperature range of 50-65 ° C by gas-tight feed and delivery. Mature compost should be used, if necessary, for example. according to soil conditions, it can be supplemented ex post, for example. with chemicals containing nitrogen, phosphorus and potassium.

According to an object of the invention, the present invention provides a process for the production of compost and biogas from agricultural by-products and agricultural wastes using cereal straw and fresh fertilizers as a starting material, optionally supplemented with other plant wastes, adjusting, blending, grinding , compacted, fed to a fermenter with a gas-tight seal, added to the crude blend as an inoculant and then fermented to form a biogas, compost and slurry compost, preferably fed continuously from the fermenter. % vegetable matter 30 is cut into pieces up to 30 mm in length, and 20-30% by weight of fertilizer, preferably cattle manure and slurry compost or other fermentation material, is added to the mixture. The resulting crude mixture is homogenized, concentrated, and has a dry solids content of about 50-80%, a pH of 6-7.5 and a C / N ratio of 10: 1-30: 1, 50-65 '. Heat to C and transfer to a fermenter with a gas tight seal. The temperature is still maintained at 50-65 ° C, the pH is 6-7.5, fermented for 40 4-20 days, the biogas formed is removed, and the compost and slurry compost are optionally supplemented with absorbent material and chemicals. .

A further feature of the process according to the invention may be the use of 50-801% agricultural by-products and agricultural waste and 20-301% fresh manure, preferably from ruminant animals, in the preparation of the crude mixture.

A further feature of the process is that the ratio of the crude mixture to 50 C / N is varied by varying the ratio of plant material, slurry and slurry compost, e.g. adjusted with about 10: 1 C / N cereal straw and / or dairy cattle fertilizer and optionally increased with about 400: 1 C / N reed waste and / or 1:35 about 55 C / N laying hen fertilizer.

The technical advantage of the process according to the invention is that the polluting and waste materials can be converted into environmentally friendly useful materials, utilized as compost and biogas. 60 manure and urine from livestock farms can be used continuously to reduce soil contamination, nitrate contamination and contamination of living waters. A further advantage is that the process can be used to compost starting material with a dry solids content of 50-80% by weight, thus mixing cereal straw and vegetable waste, which would be destroyed by burning stubble or otherwise. The resulting compost also has a dry matter content of at least 30% by weight, is easy to handle and has a low environmental impact. The resulting biogas is of good quality, with a methane content of at least 501% and a calorific value of at least 18,000 kJ / m ³ . The process allows continuous feed and yield.

The economic advantage of the process according to the invention is the utilization of waste as well as the utilization of manure, urine and plant waste and grain straw produced in animal breeding plants as high quality biogas and compost. It also has the advantage of reducing environmental and soil pollution. The thermal energy of the biogas produced during composting exceeds the energy required to maintain the fermenter and can therefore be used for other purposes.

The invention will now be illustrated by way of an exemplary embodiment, without, however, limiting our claims therein.

Example

Composting and biogas production was performed at 250 dairy cattle farms (one animal dispenses about 30 kg of litter manure and 18 kg of urine per day).

The fermenter was placed below ground level to reduce heat loss, and the heat needed to heat and maintain the temperature was provided by a gas generator powered by the biogas produced. 7500 kg of cattle bedding and 25 000 kg of pre-ground cereal straw, 250 kg of cane waste, 250 kg of vegetable stalk, 250 kg of corn fiber and sturgeon were homogenized by blending and shredding. It was gas-tightly fed to the fermenter conveyor and fed to the fermenter. The dry matter content of the mixture was 781%. The pH of the mixture was adjusted to 7.5 by the addition of slurry and 1500 kg of slurry was used. The mixture was heated to 65 ° C. During the fermentation, the temperature, the gas composition and the pH of the effluent were checked every 6 hours. When the pH dropped below 6, 500 kg of warm slurry was added and the temperature was maintained above 55 ° C.

Under certain conditions, 18,000 kg of compost and 8,400 m ^{3 of} biogas were produced during a 10-day fermentation period.

The compost had a dry matter content of 65%, with a dry matter content of 15% by weight of humus, 50 ppm nitrite nitrate, 1000 ppm phosphorus and 200 ppm potassium. The compost was used for soil improvement.

The biogas developed had a calorific value of 21,000 kJ / m ^{3 and} was composed of 72% methane, 21% carbon dioxide and 71% other gases, mainly ammonia and nitrogen.

Claims (3)

PATENT CLAIMS A process for the production of compost and biogas from agricultural by-products and agricultural wastes using as starting material cereal straw and fresh manure, optionally adding additional vegetable wastes, adjusting the dry matter content of the crude mixture, mixing, slicing, compacting, gas-tight compacting, adding the slurry slurry or slurry compost or other fermentation agent to the crude mixture and then draining the resulting blend to form biogas, compost and slurry compost, preferably continuously from the fermenter, with a concentration of 50-80% by weight of the plant. the material is comminuted into pieces up to 30 mm in length, 20-301% fertilizer, preferably cattle manure and slurry compost or other fermentation agent is added as a vaccine to the mixture. the crude mixture is homogenized, concentrated, and has a dry matter content of about 5080% by weight, a pH of 6-7.5 and a C / N ratio of 10: 1-30: 1 at 50-65 ° C. it is then heated to 50-65 ° C, the pH is maintained at 6-7.5, fermented for 4-20 days, the resulting biogas is removed, the compost and the and, where appropriate, absorbent material and chemicals are added to the dilute compost. Process according to claim 1, characterized in that both the introduction of the raw materials into the fermenter and the removal of the biogas, compost and slurry compost formed during the fermentation are carried out continuously in a closed system with the preservation of the bacterial cocoate formed. 3. A process according to claim 1, wherein the C / N ratio of the crude mixture is varied by adjusting the ratio of plant material, slurry and slurry compost, and the C / N ratio of the crude mixture is set between 10: 1 and 30: 1. , and optionally modified with about 400: 1 C / N reed waste or about 35: 1 C / N laying hen manure. Published by the National Office for Inventions, Budapest Responsible: dr. Gabriella Swoboda Head of Department