FR2990943A1 - Breathable superabsorbant agrogranule, useful for absorbing and storing water or aqueous solution for supplying dissolved elements e.g. nitrogen, to crop, comprises mixture of proteinic biopolymers and polysaccharidic biopolymer - Google Patents

Abstract

Breatheable superabsorbant agrogranule having a dry matter rate of 92-95%, comprises: a mixture of 55-60% of proteinic biopolymers, rich in globulines, albumins, prolamins and fibers, consisting of protein vegetable matters including sunflower, soya, colza, alfalfa and flax, and 40-45% of polysaccharidic biopolymer, rich in starch, hemicelluloses and pectins, consisting of seed flours of cereals or sugar beet pulp; and 5-40% of natural tissue or hyaline hydrocysts cells from living plant material including Sphagnum or Carduus thistle. An independent claim is included for preparing the breathable superabsorbant agrogranule, comprising: mixing the proteinic biopolymers and polysaccharidic biopolymers after crushing; adding the natural tissue or hyaline hydrocysts cells after crushing; introducing the solid mixture in an extrusion device; introducing a process liquid, in which a sulfite salt and glycerol are dissolved to obtain a mixture of matters including 10-45% of water; processing the mixture at a temperature of 80-120[deg] C in the extrusion device; then undergoing operations of malaxation, plasticization and plastic material formation under a pressure followed by cutting in a wished gauge; steaming in a tunnel under an air flow at a temperature of 40-55[deg] C for 30 minutes to obtain the gauged agrogranule; and drying up to 92-95%.

Description

The present invention relates to superabsorbent breathable agrogranulates obtained by a manufacturing process based on the combination of natural native proteins and polysaccharide polymers on the one hand and of a structural component made of natural tissues of hyaline cells on the other hand. or hydrocysts with high water storage capacity. Said superabsorbent breathable agrogranulates are intended to store water-soluble elements that are certainly nutritious for the crops, but potentially polluting the waters, in order to release them in a controlled manner according to the needs of the plants and to the extent of their threshold of hydro-solubility, stopping thus water pollution avoiding eutrophication.

Currently, fertilizers are applied by spreading in the fields. But all fertilizers, both liquid and water-soluble, are driven largely by water, both rain and water, to pass into surface water (plans and rivers) by runoff and into groundwater ( groundwater) by infiltration. We talk about leaching soils polluting rivers and groundwater. Protective measures taken to date are: - limitation of the quantities of fertilizers used, which is difficult in the case of intensive agriculture practiced today; - the establishment, between two planting cycles, of transitional crops intended to consume the fertilizers remaining in the soil after harvest of the main crops. But this does not prevent the rains from dissolving the said fertilizers and dragging them towards the waters, between the harvest and the time that the transitional seedlings have produced the protective vegetation; - Organic farming is also cited as a groundwater protection measure. This is true from the point of view of chemical fertilizers that are not used in this case, but not necessarily for biological elements that are well-suited to water and environmental pollution.

Overall, all these measures are still insufficient to protect the waters from pollution caused by agriculture. In order to minimize pollution of organic origin by the production of large quantities of nitrates which, in combination with phosphates, can lead to the eutrophication of surface water, more and more agricultural waste and food industries are subject to anaerobic digestion. The methanation digestates obtained, liquid or more concentrated, are used as fertilizer by spreading. But this operation, difficult to achieve, generates environmental discomfort due to odor and leachate flow. On the one hand, the logistic conditions of transport and reception of very strongly odorous liquid digestates contribute to this difficulty of application, and on the other hand the already dissolved substances are even more easily driven by the runoff water, thus contributing more surely. to pollution.

The present invention is carried out in the context of the improvement of the invention described by the application FR 2 940 297 filed on December 18, 2008 under the title "Composite plastic material in the form of granulates derived from vegetable protein materials and its process "by AB7 Industries.

The agrogranulates obtained according to the process disclosed by FR 2 940 297 are formed from a composite material combining a thermoplastic matrix of a polypeptide nature with a fibrous reinforcement of lignocellulosic nature. In the implementation according to the application disclosed above, agrogranules have certain limits, the main ones being: - water content of the agrogranulate at equilibrium with the ambient air at 25 ° C. which varies between 7% and 40%; relative humidity and 18% at 80% relative humidity, which is an indication of fragility in the face of moisture. - Disintegration of the agrogranulate as soon as it is put in a 100% humidity situation. - Destabilization of the agrogranulate matrix as soon as the absorbed water content reaches 150% of the weight of agrogranulates. - Capacity of water retention and aqueous solutions up to 150%, but under these conditions the matrix eventually degrade. The prior art thus discloses an absorbent support in the form of agrogranulate in which it is possible to incorporate water-soluble elements. However, under actual conditions of use, the agrogranulates described in the prior art lose the stability of their structure until disintegrating when the amount of water or absorbed aqueous solution exceeds a rate of 150% based on their weight. , or when the relative humidity exceeds 80%.

Already, therefore, the prior art proposes to improve the resistance of the matrix of these agrogranulates to moisture, by modifying its composition by adding biodegradable synthetic polymers, resistant to water, of polyester type (polycaprolactone ( PCL) and polyvinyl alcohol (PVA)), polyamides, polypropylene, polyethylenes and biosynthetic polymers of biodegradable polyester type (polylactic acid (PLA), polyhydroxyalkanoates ...), lignosulphonates, etc. These polymers, which decrease the affinity of the matrix for water, promote its stability against moisture, but strongly restrict its ability to absorb and store water or aqueous solutions of mineral, organic or biological substances.

There is therefore a need to provide a new formulation to obtain a biodegradable agrogranulate able to absorb a very large amount of water or aqueous solutions.

To better understand the invention, the term "superabsorbent breathable agrogranulate", singular or plural, a granule obtained by the plasticization of polymers of plant origin and having a high water absorption capacity or aqueous solutions in water. increasing in volume, then returning to its original volume by desiccating.

By "solid" or "solid mixture" is meant the mixture of natural protein and polysaccharide polymers with natural tissues of hyaline cells. The term "liquid" or "process liquid", singular or plural, means water or an aqueous solution of mineral or organic nutritive or protective elements for plants, or a biological aqueous dispersion of microorganisms useful for development. Plant. The term "aqueous solution", singular or plural, any water-based solution of any substance useful to plants. The term "liquid methanization digestate", singular or plural, the liquid co-product obtained during the methanization of solid and liquid organic materials, for the production of methane. The digestate of liquid methanization is comparable to a solution or an aqueous suspension. The term "natural tissue of hyaline cells or hydrocysts", singular or plural, a crushed plant, particularly rich in this type of cells that are good reservoirs of water. The present invention proposes to provide a superabsorbent breathable agrogranulate of 92% to 95% dry matter after steaming for the removal of water from the process liquid, capable of storing a large quantity of water-soluble mineral or organic elements or a mixture thereof, as well as hydro-dispersible biological elements. Said stored elements will be released in time and in a controlled manner, at the limit of their water solubility threshold absorbed by the agrogranulate, according to the needs of the plants. Since said superabsorbent breathable agrogranulate can absorb more water than its absorbent capacity, it keeps much of the undissolved stored material and thus provides an effective solution to soil leaching. Another object of the invention is to provide a superabsorbent breathable agrogranulate to the methanation digestates without bad smells and having 92% to 95% dry matter, both to solve the logistical problems posed by the distribution and spreading of liquid methanation digestates, and to eliminate the environmental inconvenience due to their unpleasant odors.

Another object of the invention is to provide a process for producing the superabsorbent breathable agrogranulate, loaded with water-soluble mineral or organic elements, or their mixture. Said agrogranulate can be the support of hydro-dispersed biological elements (soil microorganisms known to those skilled in the art, rhizobium inoculum).

For this purpose, the superabsorbent breathable agrogranulate according to the invention having a dry matter content of between 92% and 95% has the particularity of being able to absorb and store water or an aqueous solution, between 170% and 520% by weight of its weight, to deliver to the cultures the dissolved elements, without losing by leaching and without disintegrating, while keeping, after dehydration, the ability to rehydrate to continue to deliver the necessary quantities of water and water. substances dissolved in plants by a matrix consisting of: a mixture of biopolymers consisting of i. 55% to 60% protein biopolymers rich in globulins, albumins, prolamins and also high in fiber, selected from the byproducts of proteinaceous vegetable matter (sunflower, soybean, rapeseed, alfalfa, flax) and ii. 40% to 45% polysaccharide biopolymers rich in starch, hemicellulose and pectin, selected from cereal seed meal or sugar beet pulp. b). 5% to 40% of natural tissues of hyaline or hydrocyst cells relative to the weight of the solid mixture, chosen from living plant materials: Sphagnum or Carduus thistle.

The matrix according to the invention is formulated with process liquid, the majority component of which is chosen from water, an aqueous solution or a liquid methanation digestate. According to one embodiment of the invention, the superabsorbent breathable agrogranulate at the digestate of methanization is obtained with a matrix formulated with the same proportions of solid listed above, but with liquid methanization digestate replacing water or a solution aqueous. Said agrogranulate obtained, which is 92% to 95% dry matter after steaming to remove the water provided by the liquid methanization digestate, has the same characteristics already described in addition to the advantage of being loaded in all materials mineral and organic provided by said digestate, without the odors emanating from the starting liquid. Said agrogranulate according to the invention is thus loaded with mineral substances respecting the favorable nitrogen / phosphate / potassium balance "NPK" according to the needs for the development of plants, or organic materials (organic nitrogen, enzymes and organic nutrients), or a mixture of these. These elements are provided by the process liquid.

According to one embodiment of the invention, the superabsorbent breathable agrogranulate is a carrier of biological elements, soil microorganisms known to those skilled in the art or a rhizobium inoculum, in water dispersion. Said biological elements are loaded into the agrogranulate by absorption of the water dispersion. Experiments have made it possible to demonstrate that the combination of protein polymers / polysaccharide polymers / natural tissue of hyaline cells in the range of the proportions defined according to the present invention, gives the agrogranulates a phenomenon of increasing in volume by absorbing water or an aqueous solution without disintegrating, then to resume their initial volume by dehydration. This phenomenon can be repeated as many times as desired and justifies the name of breathable agrogranulates obtained according to the invention. According to a preferred composition which leads to the best results, superabsorbent breathable agrogranulate is obtained from a plastic composite matrix formulated with native natural components selected from: a). Protein biopolymers rich in globulins, albumins, prolamins (without being exhaustive) and also rich in fibers, chosen from byproducts of proteinaceous vegetable materials: oilseed meal (sunflower, soya, rapeseed, alfalfa, flaxseed) . Sunflower oil cake is a by-product of sunflower oil production. b). starch-rich polysaccharide biopolymers, hemicelluloses and pectins, selected from cereal grain flours and sugar beet pulp. The example beet pulp is a by-product of the sugar industry. vs). the natural tissues of hyaline cells or hydrocysts with a high capacity of water reserve, chosen from living plant materials: Sphagnum or Carduus thistle. Sphagnum as an example is a plant that has a great capacity to store water that can gradually release in a situation of lack of water or drought. According to a preferred embodiment of the invention, the process liquid comprises: 2% to 5% sulphite salt mixed with 8% to 12% glycerol and dissolved in a. 87% to 90% water or b. 87% to 90% of an aqueous solution of mineral or organic materials, or a mixture thereof, or c. 87% to 90% of a liquid methanation digestate. According to one embodiment of the invention, in the aqueous solution are dissolved inorganic materials (nitrogen, phosphate, potassium), or organic materials (organic nitrogen, enzymes and organic nutrients for plants) or their mixture. Said solution is prepared taking into account the needs of the plant to be treated and the state of the soil. According to another embodiment of the invention, the liquid methanation digestate has a content of between 1% and 12% of dry matter consisting of organic matter, organic nitrogen, ammonium nitrogen, phosphate (P 2 O 5) and of potassium (K20). Being of aqueous base, the liquid methanization digest can be a medium for dissolving other nutrients for the plant, depending on the desired balance and effects. Thus, the nitrogen, phosphate or potassium content is adjusted by adding these elements to the liquid digestate.

According to one embodiment of the invention, the biological contributions can be of the microorganism type, for example a hydro-dispersed rhizobium inoculum or soil bacteria known to those skilled in the art, which do not tolerate a high temperature. said microorganisms being liquid phase by water dispersion, to be incorporated into superabsorbent breathable agrogranulates by simple absorption at room temperature. The superabsorbent breathable agrogranulate according to the invention can be obtained by carrying out the process which consists in: a). mix after grinding the protein biopolymer in proportions of 55% to 60% and the polysaccharide biopolymer in proportions of 40% to 45%, b). add to the biopolymer mixture obtained in a). natural tissue of hyaline cells or hydrocysts with high capacity of ground water reserve, in proportions of 5% to 40% with respect to the whole solid mixture, c). introduce the solid mixture thus obtained in b). in an extrusion device, d). introducing the process liquid, in which a salt of sulfites and glycerol are dissolved in adjusted proportions, so as to obtain a mixture of materials comprising 10% to 45% water, e). bring the mixture obtained in d). at a temperature between 80 ° C and 120 ° C in an extruder, f). successively mixing, plasticizing and press forming the plastic material successively followed by cutting into a desired size, g). on a belt moving in a tunnel, under a flow of air at a temperature between 40 ° C and 55 ° C for 15 minutes to 30 minutes calibrated agrogranulates obtained in f). up to 92% to 95% dry matter. An extrusion device for implementing the method according to the invention consists of a system of two corotating worms in a sheath, equipped with restrictive elements ensuring kneading under shear and the pressurization of the material, a die at the outlet of the sleeve ensuring the flow and the forming of the plastic material and a cutting system ensuring the calibration of breathable agrogranulates.

According to a directly industrializable mode of the invention, the production of superabsorbent breathable agrogranulates, on the one hand natural native protein and polysaccharide components, and on the other hand a structural component made of a natural tissue of strong cells. water storage capacity, is carried out in a twin-screw extruder, whose configuration (production capacity, introduction of solid and liquid, profile of the screws and restrictive elements, temperature and pressure profiles) is adapted by the man of craft, and equipped with a granulation device. The superabsorbent breathable agrogranulates according to the invention are planted either by "semi" with the seeds of crops or by spreading under cover of soil.

EXAMPLES The following examples serve to illustrate the invention without limiting its scope which extends to equivalent devices and compounds in terms of structure and function.

Example I: Production of breathable agrogranulates with a water-glycerol-sodium sulphite mixture as a process liquid The sunflower cake used is derived from the oil pressing industry of sun-dried sunflower seeds. It is 90.57% dry matter. It consists of: - 50% of delipidated almond particles representing 50% of the dry matter of the cake and containing 1.5 to 2% of residual lipids and 56% of proteins, - 50% of pieces of shells also representing 50 % of the dry matter of the cake and containing 41% of cellulose, 20% of hemicelluloses and 25% of lignin. The beet pulp used comes from the sugar industry. It is 90.62% dry matter. It consists of: - 71% of majority constituents: cellulose, non-cellulosic parietal polysaccharides composed by pectin and hemicelluloses; - 7% protein; 2.5% lignin and 1% lipids; - 4.6% of mineral matter Sphagnum used is harvested and then dried up to 91.26% dry matter. It consists of a tissue rich in hydrocyst cells or hyaline cells, water reservoirs.

The water used for the process is demineralized. Sodium sulphite is dissolved therein and the solution is mixed with glycerol in the proportions of 83% water, 12% glycerol and 5% sodium sulphite. This mixture is called the liquid.

The sunflower cake and the beet pulp were first mixed in a rotary mixer in the proportions of 57% / 43%. Then ground peat moss is added to the mixer for 30% of the total mixture. This mixture is called the solid.

The solid is loaded into the hopper of an extruder type EXTRAL BC45 heated in the barrel at 100 ° C, to be conveyed into the system at 24.5 kg / h, with a screw rotation at 200 rpm. The liquid is introduced into the sleeve using a pump at 17.33 kg / h, in the proportions of 39% liquid to 61% solid. .

The plastic material formed in the system converges in an 8-hole die with a pressure of 16 bar. The granulating knife allows to deliver on average 42.6 kg / h of well-formed agrogranulates, with 55.23% of dry matter, which are dehydrated on a strip for 20 minutes in a tunnel oven ventilated at 50 ° C. Dehydrated breathable agrogranulates are 95% dry matter. These dehydrated breathable agrogranulates are also superabsorbent of 500% water relative to their dry weight. EXAMPLE 2 Production of Breathable Agrogranulates with an aqueous solution of a Nitrogen-Phosphate-Potassium (NPK) complex as a process liquid A 2% aqueous solution of a mineral mixture consisting of nitrogen, phosphorus and phosphorus is prepared. potassium (NPK) and then proceed as in the first example, but with a ratio of 41`) / 0 of liquid to 59% of solid.

The results obtained are identical to those described in the previous example. Example 3: Production of breathable agrogranulates with a mixture of liquid methanisation digestate - glycerol - sodium sulphite as process liquid A methanisation digest of liquid at 1.6% dry matter is mixed with glycerol and sodium sulphite in the following conditions: proportions of 83% digestate, 12% glycerol and 5% sulphite. Then the procedure is as in the preceding example using said digestate as a process liquid, with a ratio of 41% of digestate of liquid methanization to 59% of solid.

The results obtained are identical to those already found in the preceding examples. Example 4 Incorporation of Rhizobium Inoculum in Breathable Agrogranules There are three lots of breathable agrogranulates from the three production cases presented in the three previous examples. An inoculum of liquid Rhizobium phaseoli, diluted in YMB culture medium (25%) (Yeast-Mannitol-Broth) is also available.

Each batch of breathable agrogranulates is sprayed with the diluted inoculum in a proportion of 30% relative to the weight of the breathable agrogranulates. The inoculum is absorbed instantaneously. Then the breathable agrogranulats soaked with inoculum are placed in an oven at 30 ° C for drying. They are then packaged in plastic bags, ready to be used for the treatment of legume plants. There are significant differences in the development of nodules due to mineral inputs (NPK supply) of the different batches. 30

Claims (14)

REVENDICATIONS1). Superabsorbent breathable agrogranulate with a dry matter content between 92% and 95% and the particularity of being able to absorb and store water or an aqueous solution, between 170% and 520% by weight of its weight, to deliver to dissolved elements, without losing by leaching and without disintegrating, while keeping, after dehydration, the ability to rehydrate to continue to deliver the necessary quantities of water and dissolved substances to plants, characterized in that it consists of a matrix composed of: a). a mixture of biopolymers consisting of i. 55% to 60% protein biopolymers rich in globulins, albumins, prolamins and also high in fiber, selected from the byproducts of proteinaceous vegetable matter (sunflower, soybean, rapeseed, alfalfa, flax) and ii. 40% to 45% polysaccharide biopolymers rich in starch, hemicellulose and pectin, selected from cereal seed meal or sugar beet pulp; b). 5% to 40% of natural tissues of hyaline or hydrocyst cells relative to the weight of the solid mixture, chosen from living plant materials: Sphagnum or Carduus thistle. 2). Agrogranulate according to claim 1 characterized in that it is thus loaded with mineral elements respecting the nitrogen / phosphate / potassium balance "NPK" favorable as needed for the development of plants, or organic materials (organic nitrogen, enzymes and nutrients organic) or a mixture thereof. 3). Agrogranulate according to Claim 1, characterized in that it is thus charged with all the mineral and organic substances supplied by the digestate of methanation. 4). Agrogranulate according to Claim 1, characterized in that it is a support for biological elements, soil microorganisms known to those skilled in the art or a rhizobium inoculum. 5). A process for preparing superabsorbent breathable agrogranulates comprising the steps of: a). mix after grinding the protein biopolymer in proportions of 55% to 60% and the polysaccharide biopolymer in proportions of 40% to 45%, b). add to the biopolymer mixture obtained in a). natural tissue of hyaline cells or hydrocysts with high capacity of ground water reserve, in proportion of 5% to 40% with respect to the whole solid mixture, c). introduce the solid mixture thus obtained in b). in an extrusion device, d). introducing the process liquid, in which a salt of sulfites and glycerol are dissolved, in adjusted proportions, so as to obtain a mixture of materials comprising 10% to 45% water, e). bring the mixture obtained in d). at a temperature between 80 ° C and 120 ° C in an extruder, f). successively mixing, plasticizing and press forming the plastic material successively followed by cutting into a desired size, g). In a tunnel under a stream of air at a temperature of between 40 ° C. and 55 ° C. for 15 minutes to 30 minutes, the calibrated agrogranulates obtained in (f) are incubated in a tunnel. up to 92% to 95% dry matter. 6). Process according to claim 5, characterized in that the composite matrix of which the agrogranulates are formed is formulated with the native natural components selected from: a). Protein biopolymers rich in globulins, albumins, prolamins and also high in fiber, chosen from byproducts of proteinaceous vegetable materials: oilseed meal (sunflower, soybean, rapeseed, alfalfa, flaxseed); b). Polysaccharide biopolymers rich in starch, hemicellulose and pectin, selected from cereal grain meal and sugar beet pulp; vs). The natural tissues of hyaline cells or hydrocysts with a high capacity of water reserve, chosen from living plant materials: Sphagnum or Carduus thistle. 7). Process according to claim 5, characterized in that the process liquid comprises: 2% to 5% sulphite salt mixed with 8% to 12% glycerol and dissolved in a. 87% to 90% water or b. 87% to 90% of an aqueous solution of mineral or organic materials, or a mixture thereof, or c. 87% to 90% of a liquid methanation digestate. 8). Process according to Claims 5 and 7, characterized in that the dissolved elements are nitrogen, phosphate and potassium mineral materials in a favorable "NPK" equilibrium according to the needs of the plant to be treated and the state of the soil. 9). Process according to claims 5 and 7 characterized in that the dissolved elements are organic materials (organic nitrogen, enzymes and organic nutrients) favorable according to the needs of the plant to be treated and the state of the soil. 10). Process according to Claims 5, 7, 8 and 9, characterized in that the dissolved elements are a mixture of said favorable inorganic and organic materials according to the needs of the plant to be treated and the state of the soil. 11). Process according to Claims 5 and 7, characterized in that the process liquid is a liquid methanisation digestate having a solids content of between 1% and 12%, consisting of organic materials, organic nitrogen and ammoniacal nitrogen. , phosphate and potassium. 12). Process according to Claims 5 to 11, characterized in that the biological inputs are incorporated into the superabsorbent breathable agrogranulates by simple absorption at ambient temperature of the water dispersion of the biological elements: soil microorganisms or inocula according to the needs of the plant to be treated and the state of the soil. 30 13). Use of superabsorbent breathable agrogranulates obtained according to the method described in one of claims 5 to 12, for storing and protecting the nutrients of the cultures from leaching. 14). Use of superabsorbent breathable agrogranulates according to the preceding claim characterized in that the planting is done by semi at the same time as the seeds or by spreading.