EP1940544A1

EP1940544A1 - Use of a biomaterial for cleaning up contaminated environments

Info

Publication number: EP1940544A1
Application number: EP06831007A
Authority: EP
Inventors: Emmanuel Guillon; Michel Aplincourt; Stéphanie BOUDESOCQUE; Jacques Dumonceau; Frédéric MARTEL
Original assignee: Agro Industrie Recherches et Developpements ARD; Universite de Reims Champagne Ardenne URCA
Current assignee: Agro Industrie Recherches et Developpements ARD; Universite de Reims Champagne Ardenne URCA
Priority date: 2005-10-28
Filing date: 2006-10-25
Publication date: 2008-07-09
Also published as: FR2892645B1; FR2892645A1; WO2007048921A1

Abstract

The invention relates to a derivative of bran cereals containing more no more than 10 % of material capable of being solubilized in order to eliminate organic pollutants, particularly crop protection products contained in an environment to be cleaned up by adsorbing these pollutants on the derivative of bran cereals.

Description

USE OF A BIOMATERIAL FOR THE DETERMINATION OF CONTAMINATED MEDIA

The subject of the invention is the use of a biomaterial for the depollution of contaminated media, in particular by phytosanitary products. The subject of the invention is in particular a method for eliminating plant protection products contained in a medium to be decontaminated.

Aquifers, particularly streams, are polluted by urban, agricultural or industrial wastes containing many toxic substances that are not decomposed or eliminated by natural processes. Most drinking water consumed by humans undergoes physical and chemical treatments in order to eliminate organic pollutants, especially plant protection products, in drinking water production plants.

The treatment of polluted water in urban or industrial waste water treatment plants generally consists in using:

- physical processes to remove solid or particulate elements (screening, grit removal, deoiling - degreasing);

- physicochemical treatments to remove decantable particulate matter (addition of coagulants and flocculants);

- biological treatments to remove organic matter (use of microorganisms).

At present, in a drinking water production plant, pesticides are essentially eliminated by the use of a mixture of ozone and hydrogen peroxide, followed by filtration on an activated carbon filter. Most products marketed for water treatment are carbon compounds (activated carbon, resins). The progressive depletion of fossil resources provides a favorable context for the use and development of renewable raw materials.

Nanofiltration and reverse osmosis processes have proved their effectiveness, but they are new and still not very widespread because of their cost of implementation.

Furthermore, it is known that the organic matter composition of the soil has an effect on the sorption of phytosanitary products, the organic matter being mainly composed of lignins and mimic acids. Thus, Spark et al. (Sci., Total Environ., 2002, 298: 147-161) showed that the adsorption of three phytosanitary products, atrazine, isoproturon and Paraquat on soils is influenced by the soil content of organic and inorganic components in the solid state.

Chaabane et al. (J. Agr Food Chem, 2005, 53: 4091-4095) have shown that the adsorption of sulcotrione, a phytosanitary product, on soils is mainly influenced by the clay content of soils, while the pH and the material organic have little effect.

The study by Beck et al. (Chemosphere, 1996, 32: 2345-2358) on isoproturon and atrazine sorption by clay soils showed that the sorption of isoproturon is modulated by the presence of organic matter, whereas the sorption of atrazine is affected by the presence of mineral compounds.

Soil composition seems to play a role in the transport of phytosanitary products in the soil, but the complexity of the soil composition does not predict the sorption capacity of only one of its constituents isolated from the soil.

There are currently few bio-filters for the removal of plant protection products contaminating media.

Antoine et al. (Environ Chem Lett, 2003, 1: 175-178) investigated the sorption capacities of two plant protection products, isoproturon and dimetomorph, on a lignocellulose residue extracted from wheat straw. They showed that lignocellulose seems to effectively retain these two phytosanitary products on this lignocellulose residue.

However, the lignocellulosic residue of straw has not been used for larger scale applications.

With regard to lignocellulosic residues of bran, the agro-food industries working cereals (flour milling, starch milling, corn mill) produce sound in large quantities, but these co-products are poorly valued. To date, the sound is mostly used in food, especially for animals. In order to increase the valuation of. these co-products, researches were carried out to extract the hexoses and pentoses of the sound which are used for the synthesis of surfactants of plant origin (Bertho et al, patent number EP 0 699 472). After this extraction of sugars from hemicelluloses, lignocellulosic derivatives of the sound remain.

The purpose of the invention is to propose a process for the recovery of a certain category of lignocellulosic derivatives allowing the depollution of media contaminated with plant protection products. The invention aims to provide a method for solving pollution problems by plant protection products, without using non-renewable natural fossil resources, and therefore meeting ecological objectives.

The object of the invention is to propose an economical process making it possible to use lignocellulosic derivatives present in abundance for the purpose of cleaning up media contaminated with plant protection products, which are capable of being eliminated during a subsequent stage of destruction easily implemented. work and ecological.

Another object of the invention is to propose a process for the depollution of aquifers by decreasing the phytosanitary concentration at concentrations lower than those authorized by current legislation.

The present invention relates to the use of cereal-ses derivatives for removing organic pollutants contained in a medium to be cleaned by adsorption of said pollutants on cereal bran derivatives.

The subject of the present invention is in particular the use of derivatives of its container at most 10% (by weight) of material capable of being solubilized, in order to eliminate organic pollutants, in particular plant protection products, contained in a medium to be decontaminated, by adsorption of said pollutants on cereal bran derivatives.

The material contained in the bran derivatives and capable of being solubilized represents a percentage sufficiently low to prevent the phytosanitary products remaining in solution, adsorbed on the soluble material, and thus to be in conditions such that it can not be used. in the adsorption of organic pollutants by bran derivatives.

Sound is a co-product of the processing of cereals in milling, resulting from the milling of the grain which separates it into three distinct fractions: flour (a starchy albumen), germ and bran. Coming from an industrial milling process, the proportion of bran, in relation to flour and germ, varies according to the milling pattern. This milling operation of the wheat grain is generally carried out according to a conventional method of progressive grinding by the dry route.

"Sound" or "sounds" means envelopes, pericarp (transverse cells, tubular cells, hypodermis and epidermis) and integuments (aleurone layer, hyaline band and seminal integument) of cereal seeds, obtained after grinding of cereal seeds. and separation by grain size of flour and bran. The sounds contain, if necessary, residues of flour and germ. By "sound derivatives" is meant the products obtained during the treatment of the sound, the final product being the lignocellulosic substrate of bran, also called lignocellulosic residue of bran.

By "organic pollutants" is meant any organic molecule likely to compete with the phytosanitary products in the adsorption on bran derivatives, and especially the phytosanitary products also called pesticides.

Thus, in an aqueous medium in which there are organic pollutants other than plant protection products and plant protection products, the adsorption of phytosanitary products on the bran derivatives can be reduced by the adsorption of other organic pollutants on these derivatives of bran. .

Adsorption involves hydrophobic, hydrophilic, electrostatic and ionic interactions between organic pollutants and bran derivatives.

The present invention results from unexpected results obtained in the context of the adsorption of phytosanitary products on bran derivatives. The inventors have shown that the bran derivatives, and in particular the lignocellulosic substrates, have adsorption capacities with respect to organic pollutants such as plant protection products substantially equivalent to most of the adsorbents currently used, and have costs of obtaining and implementation very advantageous with respect to these adsorbents. The results obtained demonstrate the interest of their use as biofilters.

According to an advantageous embodiment, the bran derivative is chosen from, the bran essentially devoid of starch (its de-ionized), the bran essentially free of starch and phytic acid (its dephytised), the lignocellulosic substrates derived from hydrolysates of its désamidonné or the ligno-cellulosic substrates resulting from the hydrolysates of its déphytisé.

Subsequently, the term "lignocellulosic substrates" designates one or other of the lignocellulosic substrates derived from the hydrolysates of its de-amidated and lignocellulosic substrates derived from hydrolysates of its dephytised.

The sound essentially starch-free, called "de-acidified sound", is obtained after washing the raw bran with hot water, followed by the elimination of the liquid phase.

The sound, which is essentially free of starch and phytic acid, called "dephytised sound," is obtained after washing the crude bran with water in an acid medium, followed by the elimination of the liquid phase. The hydrolysates of its de-amidated and the hydrolysates of its dephytised, are obtained after acid hydrolysis, respectively of the deodidated and dephytised sound.

The lignocellulosic substrates are obtained after alkaline treatment of the hydrolysates of bran.

According to an advantageous embodiment, the bran derivatives come from the treatment of cereals chosen from at least one of the following cereals: wheat, oats, barley, buckwheat, millet, sorghum, rice, maize, rye and in particular from plants belonging to the Poaceae family, especially chosen from: Triticum sp. (wheat), Zea mays (maize), Oryza sativa (rice), Hordeum vuigare (barley), Secale cereal (rye), Panicum sp. (millet), Sorghum sp. (sorghum), Fagopyrum sp. (buckwheat), Pennisetum sp. (millet), Triticum x Secale (triticale) and Avena sp (oats).

The present invention aims to clean up media contaminated with plant protection products belonging to the group comprising at least one of the following products: acaricides, bactericides, fungicides, herbicides, nematicides, rodenticides, taupicides, molluscicides, corvicides, fumigants, insecticides.

Phytosanitary products are present in different formulations that can be liquid, solid or gaseous.

In what precedes and what follows, the phytosanitary product designates the active substance, without the agents of formulation, or the phytosanitary product in formulation. As regards the phytosanitary concentrations, they correspond to the concentrations of the active substance, without the formulants.

Fumigants are phytosanitary products designed to act in the gaseous state.

The purpose of the present invention is, in particular, to depollute environments contaminated with phytosanitary products belonging to the group comprising at least one of the following products:

- organophosphorus products, in particular glyphosate, bromophos, malathion,

- organochlorine products, especially dimetomorph,

pyrethroid products, in particular dehalethrin, permethrin, fluvanilate,

urea derivatives, in particular isoproturon, diflubenzuron, diuron, linuron,

carbamates, especially triallate, carbofuran,

triazines, especially termébuton, desethylterébébon, simazine, atrazine, terbutylazine,

carbinols, sulfones and sulfonates, aryloxyacids,

amide derivatives: alachlor, metolachlor. The present invention aims to depollute contaminated media selected from liquid media, including aqueous and / or organic media, aerial media and solid media.

In general, liquid media are aqueous media that are designated under the generic names of aquifers, and that may have been in contact with sanitary phyto.

According to the invention, the liquid media to be decontaminated are in particular effluents from industries, wastewater or cleaning of agricultural spray equipment, wastewater from these effluents, runoff water from areas that have been treated with phytosanitary, drilling or groundwater abstraction water close to areas treated with plant protection products, watercourses, ponds, lakes, wells located in areas treated with plant protection products, water from the distribution network and water treatment plant.

The subject of the present invention is in particular the use of cereal bran derivatives to depollute slightly loaded effluents, essentially contaminated with plant protection products. The term "lightly discharged effluents" refers to effluents that contain at least 10% phytosanitary products (in moles) relative to the dry matter of the effluent. These "lightly laden" effluents have in particular been freed of solid elements, as well as oils and greases, during pre-treatment in the treatment plants.

During pretreatment or primary treatment in sewage treatment plants, certain plant protection products may be removed in a non-specific manner. For example, plant protection agents can be trapped in clays during routine decantation operations or they can be removed in the screening step after adsorption on large organic residues.

According to the invention, the air media to be decontaminated are in particular the atmosphere contaminated with aerosol sprays of phytosanitary or confined atmospheres.

By "spray aerosol phytosanitary" is meant phytosanitary contained in droplets that are suspended in a gaseous medium.

"Confined atmospheres" means, in particular, the atmosphere in greenhouses, aboveground crops, the atmosphere of which is likely to be poorly renewed or driven locally to confined systems by means of mechanical ventilation or convection, and atmosphere breathed by operators through masks.

"Aboveground crops" means crops grown in a root environment that is not the natural soil, but a reconstituted and isolated soil medium. The cultures in confined atmospheres are carried out under conditions allowing to control the temperature, the rainfall, the humidity, the wind, the absence of predators, in order to realize difficult crops, sensitive, or out of seasons.

The air environment can be polluted by volatile pesticides and / or contained in droplets when using aerosols.

The air environment is particularly contaminated:

- when using fumigants in which the plant health products are in the gaseous state, and / or

when spraying with aerosols in which the plant health products are contained in droplets suspended in the air environment, and / or

- when using plant protection products that are totally or partially volatile under the conditions of use.

According to the invention, the solid media to be decontaminated are in particular the soils, in particular the cultivated or uncultivated soils, sheltered or not from precipitations and greenhouses, especially confined.

In the case of above-ground crops or non-cultivated areas between crops (access roads), the soil may be replaced or covered by a specific material based on bran derivatives in the form of crushed, slabs, susceptible to be easily exported once subjected to the exposure of phytosanitary products, in particular by spraying, and saturated with phytosanitary products.

The saturation rate corresponds to the adsorption capacity of the sound derivative expressed as a percentage of adsorbed phytosanitary substances relative to the maximum amount of adsorbable molecules. When there is no longer any adsorption for a phytosanitary product, it is considered that the saturation level of the bran derivative for this product is 100%.

In order to depollute solid media, the bran derivative may for example be deposited in the form of a powder of high particle size (for example 2 mm) in ditches or, in the form of crushed on the surface of cultivated areas. Phytosanitary products come in contact with the derivative of its particular by leaching and runoff.

Thus, in both cases, the derivative of bran is easily recovered after saturation with phytosanitary products.

According to an advantageous embodiment, the bran derivative is a lignocellulosic substrate derived from cereal bran containing about 10% to about 50% lignin and about 50% to about 90% cellulose. The raw bran contains about 3% to 10% lignin and about 5% to 20% cellulose, especially about 10 to 20% cellulose. The sum of the percentages of lignin and cellulose does not exceed 30%.

The essentially starch-free sound and the essentially starch-free and phytic acid-containing sound contain about 6% to 20% lignin and about 10% to 40% cellulose. Advantageously, the sum of the percentages of lignin and cellulose does not exceed 50%.

Advantageously, for the hydrolyzate of the bran and the lignocellulosic substrate, the sum of the percentages of lignin and cellulose is greater than 50% and especially greater than 60%.

Lignin is a complex phenolic polymer consisting of three monomer units H (Coumaryl), G (Guaiacyl) and S (Syringyl), the respective percentages of which depend on the nature of the origin of the lignin.

Cellulose is a glucose polymer formed by long linear chains of glucose linked by β1-4 linkages.

According to an advantageous embodiment, the bran derivative, and in particular the lignocellulosic substrate, is amphiphilic and contains active sites capable of establishing hydrophilic, hydrophobic, electrostatic and ionic interactions with organic pollutants.

Active site refers to any site, including functional group of the carboxylic, ether, hydroxyl, phenolic, aromatic ring, on the surface of the derivative of sound, capable of interacting with a liquid or gaseous substrate coming into contact with this surface.

The rich lignocellulosic substrate of its in fatty acids increases its amphiphilic character. Indeed, both the hydrophilic nature of the carboxylic acids of the fatty acids and the hydrophobic character associated with the carbon chains are increased. Despite the increase in the amphiphilic character, the lignocellulosic substrate has very interesting adsorption properties.

In comparison, the lignocellulosic straw substrate, which is low in fatty acids, can establish either hydrophobic or hydrophilic interactions with plant protection products, but it has a lower amphiphilic character than the lignocellulosic substrate of bran. When decontaminating solid media with a derivative of its solid, the supply of water, for example rainwater, allows the phytosanitary to be brought into contact with the bran derivative and thus allows the establishment of hydrophobic, hydrophilic, electrostatic or ionic type.

The amphiphilic interactions take place in the presence or absence of an aqueous medium. During the clearance of the air environment, the phytosanitary state of gas can be fixed on the derivative of its in the absence of an aqueous microenvironment.

The bran derivative, and in particular the lignocellulosic substrate as defined previously, contains fatty acids having from 6 to 28 carbon atoms, simultaneously enhancing the hydrophilic character of the bran derivative, and especially the lignocellulosic substrate, by the intermediate of carboxylic groups, ethers and hydroxyls, and the hydrophobic character, via aliphatic chains and aromatic rings. The ligneous fraction very rich in aromatic compounds plays an essential role and allows the formation of hydrophobic type interactions. In general, the more the compound is rich in aromatic nucleus, the greater its adsorption capacity vis-à-vis phytosanitary products will be important.

The derivative of bran, and in particular the lignocellulosic substrate of its as defined above, is negatively charged as of pH 3.

The negative charge of the sound derivative promotes the adsorption of cationic compounds and disadvantages that of anionic compounds and is a priori without impact on the neutral compounds.

The invention thus applies in the pH range encountered, namely between pH 6 and 9. Some soils are more acidic, but it is essentially forest soils, not subject to phytosanitary treatments, or very localized, as for example the center of Brittany. It is however exceptional that the pH is less than 5 or greater than 9.5.

For example, the average pH of French soil varies from 7.7 to 8.5 and the pH encountered in water when treated in treatment plants are between 5.5 and 9.5.

The lignocellulosic substrate as defined above consists of approximately 51% carbon, approximately 7% hydrogen and approximately 42% oxygen. The percentage of nitrogen is systematically less than 4%.

The concentration of acidic surface sites corresponding to the carboxylic sites is about 0.65 mmol / g and that corresponding to the phenolic sites is about 0.40 mmol / g, and the density of acidic sites is about 3 sites. / nm ² . The presence of saturated and unsaturated long chain fatty acids can be demonstrated by pyrolysis or thermochemolysis (Ahmad, R. et al., Environ Sci., Tecnol., 2001, 35: 878-884).

XPS, IR and NMR CP-MAS ¹³ C spectroscopies demonstrate the presence of aromatic rings and ether, hydroxyl and carboxyl groups.

The specific surface area, measured by BET (Brunauer-Emmett-Teller) with water vapor, is about 200 m ² / g. The specific surface area represents the total area per mass imity of the lignocellulosic substrate accessible to the phytosanitary product molecules. It is therefore to consider the entire surface of each particle, open porosity included. The physical principle, universally recognized for the determination of a mass area, as the specific surface, is based on the adsorption of gas at low temperature.

According to an advantageous embodiment, the bran derivative is a bran essentially starch-free or a bran essentially free of starch and phytic acid, as obtained by subjecting, optionally ground, cereal bran to a process comprising:

a step of washing the sound, to obtain the washed sound,

followed by a liquid - solid separation carried out on the washed bran to remove the solubles and starch from the flour.

The cereal bran can be crushed, before washing, to obtain a grain size ranging from 5 mm to 100 microns.

The sound essentially starch-free is obtained by washing with hot water at a temperature of 50 ° C. to 80 ^° C., in particular from 60 ° C. to 80 ° C.

The washing with hot water is carried out at a temperature above 50 ° C so that the solubilization kinetics of the water-soluble products is rapid, and at a temperature below 80 ⁰ C to avoid hydrolysing the hemicelluloses. We then obtain, after separation liquid / solid, a solid called in the above "his désamidonné".

The sound essentially free of starch and phytic acid is obtained by washing the bran derivative at a water temperature of between 0 and 50 ° C., and in particular with cold water of 10 ^° C. at 20 ^° C., in an acidic medium. at pH 1-2, in particular using a solution of H ₂ SO ₄ .

Washing in an acidic medium makes it possible to promote the solubilization of certain compounds such as phytic acid which is valorized by other sectors, as well as starch. This washing must be carried out under cold conditions, at a temperature of less than 50 ° C., in particular between 10 ^° C. and 20 ^° C., in order to avoid deterioration and coloration of the pentoses which are harmful to recovery. higher. Then, after separation liquid / solid, a solid essentially free of starch and phytic acid, called in the above "dephytisé".

The sound washing step allows the passage of water-soluble products, including starch, in the liquid phase.

The solid-liquid separation step is carried out in particular by pressing, in particular by screw and cage press, or by decantation by centrifugal decanter, or by filtration on a filter press.

This step makes it possible to eliminate the following solubles: short chain organic acids, sugars, minerals, soluble proteins and starch flour. Flour starch is the residual starch of the milling process which was not recovered during the brushing of the seed coat after grinding of the grain.

This solid-liquid separation step, described as de-scaling, is not essential, but facilitates the subsequent purification of the products.

The essentially starch-free sound contains less than 10% starch. Sound essentially free of starch and phytic acid contains less than 10% starch and less than 1% phytic acid.

According to an advantageous embodiment, the bran derivative is a hydrolyzate of its deionized or of its dephytised as obtained by acid treatment of cereal bran to eliminate starch, emicellulose and proteins, and in particular by submitting bran cereal, optionally ground, to a process comprising the following steps: a washing step of the sound, as described above, to obtain the washed sound, a liquid-solid separation step performed on the washed sound, as described above, to obtain dehydrated sound or dephytised sound, - a stage of acid hydrolysis of the de-acidified or dephytised sound to obtain a hydrolyzate of its deionized or dephytised.

The hydrolysis step is carried out using an acid, for example using a solution of H ₂ SO ₄ , at a pH of about 1 to 2, at a temperature above 80 ^° C. This step makes it possible to hydrolyze the hemicelluloses present in simple sugars, as well as any residual starch in glucose and the proteins not solubilized previously in amino acids. Acidic chemical treatment enhances the adsorption properties of bran derivatives. By way of example, when 11.2 mg of terbumeton are brought into contact, at pH 6, with different bran derivatives, the amounts of terbumeton adsorbed are: 0.09 mg on the crude bran, - 1.07 mg on the deamidated sound,

- 1.51 mg on the dephytised bran, and

- 6.85 mg on the lignocellulosic substrate.

From these results, there is also a non-linear increase in the adsorption of the bran derivative as its lignocellulose content increases.

The hydrolyzate of its désamidonné or dephytisé obtained consists of a liquid phase of soluble products, which phase is rich in pentoses (arabinose, xylose) from hemicelluloses, and a solid phase, consisting essentially of raw lignocellulosic substrate .

According to an advantageous embodiment, the bran derivative is a crude lignocellulosic substrate as obtained by acid-base treatment of cereal bran to eliminate starch, emicellulose and proteins, and in particular by subjecting cereal bran, optionally milled, to a process comprising the following steps: a washing step of the sound, as previously described, to obtain the washed sound, a liquid-solid separation carried out on the washed sound, as previously described, to obtain the de-ionized sound or its déphytisé, a stage of acid hydrolysis of the deamidated or dephytised sound, as described previously, to obtain a hydrolyzate of its désamidonné or déphytisé,

- A step of alkaline treatment of the hydrolyzate of its deionized or dephytized, followed by filtration to obtain a solid, lignocellulosic substrate crude.

The alkaline treatment is carried out using a base, for example using Ca (OH) ₂ , to increase the pH to about 3, and to neutralize the anions of the acid used in step acid hydrolysis. This treatment facilitates the next filtration stage at pH 3 to obtain a solid, insoluble at pH of from 1 to 10, the crude lignocellulosic substrate.

The neutralization of the anions of the acid may be important because the presence of ions on the surface of the lignocellulosic substrate, whatever they are, modifies the surface properties of the latter and may affect its adsorption capacities, especially by phenomena of competition and / or charge.

During the alkaline treatment, the pH is increased to 3 so that the lignocellulosic substrate is less fluid and thus prevent its passage into the liquid phase (filtrate) during the use of the filter press. The increase in pH also makes the lignocellulosic substrate easier to use.

Finally, in the process for upgrading the pentoses present in the filtrate, a concentration step makes it possible to precipitate the sulphates of the excess acid with the calcium, in the form of gypsum, and thus makes it possible to purify the sweet filtrate.

The filtration is in particular carried out by pressing the hydrolyzate on a filter press. The filtrate obtained, consisting of soluble lignin compounds, can be valorized thanks to its high content of pentose type sugars. In dry matter, the sugar content is between 0 and 15% of glucose, between 5 and 25% of arabinose, and between 20 and 40% of xylose.

According to an advantageous embodiment, the lignocellulosic substrate is as obtained by treatment of the raw lignocellulosic substrate:

by subjecting it to a rinsing step, to obtain a rinsed lignocellulosic substrate,

and optionally by subjecting the rinsed lignocellulosic substrate to a drying step, to obtain the lignocellulosic substrate rinsed and dried.

The rinsing step may be carried out by adding one to two volumes of cold or hot water and carrying out several filtration steps on a filter press, to obtain a residue of a dry matter of between 15 and 40%.

The drying of the rinsed lignocellulosic substrate is for example carried out on a cylindrical dryer provided with blades stirring the moist product in a hot air stream of 100 to 180 ⁰ C, until a dry matter of between 80 and 99% is obtained.

This drying serves only to stabilize the product and can be avoided if the wet product is used quickly or transported to its place of use in wet form.

According to an advantageous embodiment, the lignocellulosic substrate is as obtained by acid-base treatment of cereal bran to eliminate starch, hemicellulose and proteins, and in particular by subjecting cereal bran, possibly ground, to a process comprising the following steps:

a step of washing the sound, as described above, to obtain the washed sound,

- liquid separation step - carried out on the solid washed thereof, as described ^'above, to obtain the destarched his or her déphytisé,

an acid hydrolysis step of the de-acidified or dephytised sound with the aid of an acid, as described above, to obtain a hydrolyzate of its deionized or of its dephytised, a step of alkaline treatment of the hydrolyzate of its deionized or of its dephytylate, followed by a filtration step, as described above, to obtain a solid, insoluble at pH of from 1 to 10, the crude lignocellulosic substrate,

a step of rinsing the crude lignocellulosic substrate followed by filtration, as previously described, to obtain a rinsed lignocellulosic substrate, of dry matter between 15 and 40%, a step of drying the rinsed lignocellulosic substrate, up to a dry matter of between 80 and 99%, as described above, to obtain the lignocellulosic substrate rinsed and dried,

and a grinding step of the lignocellulosic substrate rinsed and dried to obtain the rinsed lignocellulosic substrate dried in powder form.

Before the use of its derivatives, it may be advantageous to remove the lignin molecules of molecular weight less than 1500 Da and ₅ in particular less than 1000 Da, contained in its derivative, for example by a step in suspending the bran derivative in a KOH solution followed by filtration to remove the aqueous phase containing the low molecular weight lignin molecules.

Before the sound derivatives are brought into contact with the plant protection products, the pH of the bran derivative can be adjusted to a value of about 6 to about 9.

According to an advantageous embodiment, the bran derivative and in particular the lignocellulosic substrate is used in combination with at least one of the following elements: lignocellulosic residue of cereal straw,

- clay,

- charcoal,

resins, in particular macroporous resins or gels, cationic or anionic ion exchange resins, adsorbent resins, steric exclusion resins,

- zeolites,

silica, especially diatomaceous earth, in particular kieselguhr.

The advantage of using these combinations is to improve the possible low adsorption capacity of the derivative of its, and in particular the lignocellulosic substrate, vis-à-vis certain products and expand the spectrum of action.

According to an advantageous embodiment, the bran derivative, and in particular the lignocellulosic substrate, is used in powder form and at a particle size of less than about 2 mm, in particular from about 20 μm to about 100 μm, in particular from about 50 μm to about 100 μm.

The particle size is advantageously less than 2 mm so that the bran derivative, and in particular the lignocellulosic substrate, has a specific surface area and therefore a sufficient adsorption capacity.

When the particle size varies from 20 .mu.m to 100 .mu.m, the sound derivative, and in particular the lignocellulosic substrate, has a larger surface area for exchange.

According to an advantageous embodiment, the bran derivative, and especially the lignocellulosic substrate is suspended in an aqueous medium.

By "suspension" is meant the dispersion of the bran derivative in the aqueous medium. The bran derivative can be kept in suspension by stirring the medium.

The "suspension" state of the derivative of its counteracts the sedimentation state, in which the derivative of its is deposited, by gravity, for example at the bottom of a settling basin.

The suspension of the bran derivative, and in particular of the lignocellulosic substrate, allows the bran derivative to be in conditions such that it has the maximum surface area in contact with the aqueous medium, thus increasing the possibility of contact with the phytosanitary products contained in the environment.

According to an advantageous embodiment, the phytosanitary product is solubilized in an aqueous medium to be decontaminated.

The term "solubilized in an aqueous medium to be decontaminated" denotes a phytosanitary product which is soluble or in suspension in the aqueous medium to be decontaminated, or a phytosanitary product dissolved in an organic phase which is a minority relative to the aqueous phase in the aqueous medium to be decontaminated. .

According to an advantageous embodiment, the phytosanitary product is present in a proportion of about 0.05 to about 100 μg / 1 of aqueous medium to be decontaminated.

The range of concentrations of 0.05 to 100 μg / l of plant protection products corresponds to concentrations likely to be found in nature. A concentration of 100 μg / 1 corresponds to a point or accidental pollution.

For example, 1 kg of phytosanitary products are generally used per hectare of large crop accumulated over the year, ie 100 mg / m ² . For a maximum annual rainfall of 1000 mm of water per m ² (Marne, 51), ie 1000 liters, the concentration is at most 100 μg / L in the runoff water. In addition, the spray provides about 100 to 200 liters of additional water, as well as fertilization or spreading. Condensation of aerial water vapor also increases the water supply during phase changes diurnal and nocturnal, as well as the natural evapotranspiration of plants when pumping into soil layers that may cause upwelling.

Overall, the phytosanitary product is diluted at concentrations below 100 μg / 1. Part of the plant protection product attaches to the soil, plant, organic material, or remains on the walls of the sprayer.

According to an advantageous embodiment, the bran derivative and in particular the lignocellulosic substrate is present in an aqueous medium, in suspension, at a rate of approximately 0.01 to approximately 50 g / l, in particular from approximately 1 to approximately 10 g / l. 1, aqueous medium to be cleaned.

This method of depollution corresponds to a static decantation, in which the bran derivatives are suspended in the aqueous medium to be decontaminated,

For concentrations in the derivative of bran greater than 50 g / l, the suspension can become too dense and the homogenization of the system derived from its solution / solution to be cleaned becomes difficult. The adsorption capacity of the sound derivative can then decrease significantly.

Moreover, a concentration of 50 g / l of a derivative of its allows to be sufficiently in excess with respect to the quantities of phytosanitary products present in the aqueous media to be decontaminated.

To fix the ideas, knowing that the adsorption capacity of the derivative of its is about 10 mg / g, if the concentration of phytosanitary products is of 100 μg / 1 and the concentration in derivative of its is of 50 g / 1 in the environment to be decontaminated, the derivative of its is largely in excess. However, this excess makes it possible to take into account the other organic pollutants that are likely to compete with the phytosanitary products in the adsorption on the derivative of bran. These organic pollutants include the products of organic formulations and exudates of plants (sugars, proteins, aromatic molecules, lipids).

If the concentration of the derivative of bran is less than 0.01 g / l, depending on the quantity of phytosanitary to be adsorbed, the bran derivatives may be insufficient in the solution to have an effective adsorption of the phytosanitary products.

The depollution treatment can last between 1 and 24 hours, and up to 48 hours.

According to an advantageous embodiment, the bran derivative and in particular the lignocellulosic substrate is present in an aqueous medium, at a given moment, in the form of a powder having a bulk density of 0.4 (kg / l), at a rate of approximately 0.01 kg to about 0.02 kg of substrate per liter of aqueous media to be decontaminated. This mode of use corresponds to a percolation process, in which the medium to be decontaminated is introduced continuously into a column containing the derivative of its powder form.

The term "bulk density" refers to the measured density of the powder. It is therefore the ratio between the mass of the powder and the volume occupied by the powder.

The sound derivative concentrations correspond to a given instant, but in total, the volume of medium to be decontaminated that can be introduced into the column gives a concentration (in mass of substrate / volume of medium) which is similar to the concentrations given in the where the bran derivative is suspended in the aqueous medium to be decontaminated.

In comparison, the bran derivative, in decantation mode, is suspended in a volume of aqueous medium to be decontaminated greater, by at least a factor of 10, relative to the percolation mode. Percolation makes it possible to treat a large volume of aqueous medium by using apparatus of reduced volume.

According to an advantageous embodiment, the bran derivative and in particular the lignocellulosic substrate is in the form of agglomerated powder forming a dry solid which can take the form of an object of the granulated, crushed, filter, slab and cartridge type.

In order to form the dry solid, and in particular to give it an appropriate form, a binding agent that is not capable of modifying the adsorption properties can be used, such as an inorganic (limestone, talc) or organic cement, which is inert with respect to the sites fasteners (saturated polyesters).

According to an advantageous embodiment, the phytosanitary product is present in the form of a gas and / or in solution in droplets of aqueous medium, in particular after use of aerosols, in the air medium to be decontaminated.

According to an advantageous embodiment, the phytosanitary product is present in the form of a gas at a rate of about 1 ng / m ³ to about 10 μg / m ³ and / or in solution in droplets of aqueous medium at a rate of 0.05 at 100 μg / 1 of water in suspension, in the air environment to be cleaned up.

According to an advantageous embodiment, the bran derivative and in particular the lignocellulosic substrate is present in a proportion of about 5 μg / m ³ to about 30 mg / m, in particular from about 0.05 mg / m ³ to about 3 mg / m ³ of air environment to be treated.

Below 5 μg / m ³ , the bran derivative, and in particular the lignocellulosic substrate, will not be present in sufficient quantity to retain a significant quantity of phytosanitary products. Above 30 mg / m ³ , the mass of sound derivative to be used is not advantageous in practical and economic terms. The object of the present invention is in particular to depollute media contaminated with plant protection products formulated with a wetting agent, a surfactant-type dispersant, an adhesive, an antifoam, a buffer, an anti-rebound polymer, an oil or a fertilizer. nitrogen, a dye, a humectant, a UV absorber, an anti-drift.

The term "wetting agent" designates formulating agents which reduce the surface tension and promote the spreading of the droplet of the aerosol in a thin layer (reduction of the contact angle).

By "dispersant" is meant formulating agents which allow the crop product to form a uniform layer on the treated surface.

By "surfactant" is meant agents of the wetting agent and dispersant type. Surfactants promote emulsification, dispersion, attachment to the plant and wetting. Among the surfactants, there are:

nonionic surfactants (organosilicones, silicones, alkylpolyglycosides), sometimes co-formulated with glycol, ethers or alcohol in the case of waxy products;

ionic surfactants which may be cationic (ethoxylated amines) or anionic (phosphates, sulphates, carboxylate substituents of olefin-type carbon chains);

- Amphoteric surfactants (lecithins) which have electrostatic charges canceling.

By "adhesive" is meant formulation agents which prolong the residence of the plant protection products on the treated surface.

By "antifoam" are meant formulating agents such as dimethylpolysiloxane, silica, alcohol, oil, sometimes kerosene or diesel, which reduce the formation of foam during the dissolution in the spray mixtures.

By "buffer" is meant inorganic or organic formulating agents which allow the dissolution of phytosanitary products, their expression in active form in the case of ionizable phytosanitary substances or which slow down the chemical decomposition of certain phytosanitary products by lowering the pH of the water. alkaline.

By "anti-rebound adhesive" are meant formulating agents such as guar gums, vegetable gel liners, waxes, emulsifiable oils, water-soluble polymers, which allow the plant health to resist rain and limit the rebound of the droplet on the leaf before spreading. By "oil" is meant formulation agents which participate in the penetration into the plant, but also in the emulsion of the formula by the formation of micelles. Mineral oils (from paraffin or naphthalene) or agricultural oils (triglyceride oleaginous oils or methyl esters) are used.

"Nitrogen fertilizer" means formulants such as urea, ammonium nitrate, ammonium sulphate, ammonium phosphate, used alone or as a mixture, which stimulate the growth of the plant, avoid precipitation in formulations and neutralize solutions.

The term "dye" denotes formulation agents such as organic molecules of the food type which make it possible to monitor the phytosanitary treatment in culture.

By "humectant" is meant formulators that allow the maintenance of phytosanitary solution on the surface of the plant, before its penetration, to prevent drying out and crystallization. Among the humectants, there are in particular glycerol, propylene, diethylene, polyethylene glycol, urea and ammonium sulphate.

By "UV absorbers" are meant formulating agents, especially organic antioxidants, which are used to preserve phytosanitary products.

Drift is the mechanism of movement of pesticides in the form of steam or sprayed droplets during application outside the treated site.

The term "anti-drift" denotes formulating agents such as polysaccharides, polyacrylamides, gums which avoid dispersion too far from the plant health of the crop by the wind, when spraying fine droplets.

Anti-drift thickeners (hydroxyethyl celluloses, polysaccharides, gums) increase the diameter of droplets containing pesticides and increase the viscosity of solutions during aerial spraying, and drift retardants reduce drift.

Formulants are organic pollutants that may compete with plant protection products in adsorption on the substrate.

Some formulants, such as ethoxylated amines, are poorly biodegradable and are toxic to aquatic wildlife. The invention makes it possible not only the depollution of plant protection products, but also that of agents for formulating plant protection products, in particular toxic formulating agents.

The formulation agents represent, in the majority of plant protection products formulated, 3 to 20%, and in particular 5 to 10%, of the dry mass of active ingredient. Advantageously, the bran derivative is used sufficiently in excess to adsorb both the active substance and the formulation agents of the formulated phytosanitary product, when these are present.

By way of example, Roundup ^® herbicide, marketed by Monsanto, contains 20% formulation agents relative to the dry mass of active ingredient.

According to an advantageous embodiment, the adsorption of phytosanitary products on the bran derivative, and in particular on the lignocellulosic substrate is from about 1 to about 20 mg / g.

According to an advantageous embodiment, the quantity of residual phytosanitary products in the medium to be decontaminated after adsorption of a part of the phytosanitary products initially present in the medium to be decontaminated, on the bran derivative and in particular on the lignocellulosic substrate is less than 1. μg / 1, in particular less than 0.1 μg / l, especially less than 0.05 μg / l.

The concentrations of phytosanitary products found in the media to be cleaned up are very variable, from 0.05 μg / 1 to several ing / 1 in the case of point pollution or effluents from the tank rinse, for example. Below 0.05 μg / 1, a depollution treatment is of little interest.

The percentage of elimination of phytosanitary products in the medium to be cleaned up is therefore very variable, since it depends on the nature and the concentration of the phytosanitary product present in the medium to be cleaned.

The percentage of elimination of phytosanitary products can vary from 10 to 100%. In the case of very low elimination percentages, especially less than 50%, it is possible to overcome this slight elimination:

- by increasing the concentration of its derivative in decantation systems, or

- by using several successive columns containing the derivative of its solid in percolation decontamination systems.

The concentrations of phytosanitary products obtained after adsorption on the bran derivatives, and in particular the lignocellulosic substrate, are of the same order of magnitude as those obtained with most of the currently used solid compounds (activated carbon, resins, etc.). Nevertheless, with equivalent adsorption capacity, the cost of implementing the sound derivatives is very much lower than that of the other solids, for example up to 100 times less than some resins. The subject of the invention is also a process for eliminating organic pollutants, in particular plant protection products contained in a medium to be decontaminated, comprising a step of bringing the medium to be treated into contact with a cereal bran derivative, and in particular a substrate. lignocellulosic, for a time sufficient for adsorption of pollutants on the derivative of its.

The invention particularly relates to a method using sound derivatives to clean up media at different scales:

- in treatment plants for the purpose of water purification; for this purpose, the sound derivatives can be used after the pretreatment and primary treatment stages, on a column between two basins or deposited directly in the settling basins; the objective will be to obtain water corresponding to the standard of the European directive 98/83 / EC of November 3, 1998 which sets the maximum concentrations of phytosanitary products at 0.1 μg / 1 per plant and 0.5 μg / 1 for all plant protection products;

- upstream of wastewater treatment plants, for example by spreading in "buffer" zones in catchment basins at the bottom of the catchment to collect runoff water; in a cooperative or at the operator's premises for the cleaning of tanks and treatment equipment.

By the expression "bringing the medium to be cleaned into contact with a cereal bran derivative" is meant the case where the bran derivative is in the medium to be decontaminated, in particular the liquid and aerial medium, and the case where the derivative sound is in contact with the medium to be cleaned, especially the solid medium.

During the depollution of aqueous media, bran derivatives and phytosanitary products are contained in the aqueous medium to be decontaminated and can establish hydrophilic, hydrophobic, electrostatic and ionic type interactions.

When the air environment is contaminated with aerosols, the air environment is in contact with the sound derivatives. After aerosol spraying, the droplets containing the phytosanitary products fall by gravity onto the bran derivatives and can establish hydrophilic, hydrophobic, electrostatic and ionic interactions in an aqueous medium.

When the air environment is contaminated by volatile plant protection products, the phytosanitary products can interact with the bran derivatives when the saturation vapor pressure is reached and they are present in the aqueous medium thus obtained. During the depollution of solid media, the derivatives of its solid form are in contact with the medium to be cleaned. The presence of water, for example rain water, irrigation water, allows the presence of the solid medium to be decontaminated and the bran derivatives in an aqueous medium and thus hydrophilic, hydrophobic type interactions. , electrostatic and ionic can take place.

According to the method defined above, the electrostatic charge of the pollutants does not interfere or little and the process is independent of the pH range of the effluents and soils to be treated, especially in the pH range encountered, between pH 6 and 9.

According to an advantageous method, the electrostatic charge of the pollutants does not interfere or little and the process is independent of the pH, especially for pH ranging from 2 to 10.

According to the process defined above, the cereals are chosen from the following cereals: wheat, oats, barley, buckwheat, millet, sorghum, rice, maize, rye from plants belonging to the Poaceae family, chosen in particular from: Triticum sp.φlé ), Zea mays (maize), Oryza sativa (rice), Hordeum vulgare (barley), Secale cereal (rye), Panicum sp. (millet), Sorghum sp. (sorghum), Fagopyrum sp. (buckwheat), Pennisetum sp. (millet), Triticum x Secale (triticale) Qt Avena sp (oats)

The method of elimination of organic pollutants relates to phytosanitary products defined above.

According to an advantageous embodiment, the method for eliminating organic pollutants uses a derivative of its as defined above.

The method for removing organic pollutants, in particular plant protection products contained in a liquid medium, in particular an aqueous medium, comprises suspending the bran derivative and in particular the lignocellulosic substrate in a liquid medium, in particular an aqueous medium, and optionally stirring said resulting liquid medium.

The aqueous medium can be agitated mechanically, in particular using blades, or hydraulically, by the arrival of a stream of continuous aqueous medium.

According to the process defined above, the possible presence of other pollutants, such as metal cations, with the exception of organic pollutants, in a liquid medium, affects little or very little adsorption capacity on the derivative of its and in particular the lignocellulosic substrate.

In other cases, the possible presence of other pollutants, such as metal cations, in particular copper, iron, with the exception of organic pollutants, in a liquid medium, can improve the processes as defined above. For example, in the case where the phytosanitary alone does not adsorb on the derivative of its, the addition of a metal cation, which forms a complex in solution with the phytosanitary, makes it possible to form a ternary complex which is adsorbed on the derivative of his.

It is not necessary to add metal cations in the case of aqueous media to be cleaned of the natural effluent type, because metal cations are already present and can improve the adsorption of phytosanitary products on bran derivatives.

By way of example, for isoproturon, dimethomorph, terbumeton and its metabolites, the presence of metal cations at levels found in natural waters (of the order of μg / 1 to mg / 1), no influence on the absorption by the derivative of sound.

For PVC, the presence of metal cations allows its fixation, while it is not retained in the absence of metal cations.

Finally, for glyphosate, which forms very stable complexes with copper (II), the presence of copper enhances the absorption of glyphosate at basic pH (Sheals et al., J. Coll., Interface ScL, 2003, 262, 38-47). .

According to the method defined above, in a liquid medium, the possible presence of humic acids does not reduce the adsorption capacity of the bran derivative and in some cases exalts its adsorption capacity.

For example, when 11.2 mg of terbumeton are brought into contact, at pH 6, with lignocellulosic substrate of bran or a mixture containing 75% of lignocellulosic substrate of bran and 25% of humic substance, the amounts adsorbed terbumeton is 6.9 mg on the lignocellulosic substrate and 6.8 mg on the mixture, respectively. The presence of humic substances therefore does not affect the adsorption properties of the lignocellulosic substrate of sound, and under the conditions of the experiment, the humic substance adsorbs the terbumeton in an amount equivalent to the lignocellulosic substrate.

The method of removing pollutants according to the invention comprises suspending the bran derivative and in particular the lignocellulosic substrate in the water of a water settling basin containing pollutants,

by bringing water containing pollutants into contact with the bran derivative, and in particular the lignocellulosic substrate deposited in a basin, the surface / height ratio of which is advantageously greater than 1, especially between 1 and 100,

the possible agitation of the water,

the recovery of the bran derivative, and in particular of the lignocellulosic substrate having sedimented for a time sufficient to adsorb the pollutants, for example by pumping the supernatant medium constituted by the water located on the derivative of bran and in particular the lignocellulosic substrate, up to the level of the bran derivative, and in particular the lignocellulosic substrate.

The sound derivative is either deposited at the bottom of the settling basin before adding the aqueous medium to be cleaned, or added to the settling tank filled with medium to be decontaminated. The bran derivative is suspended by the action of pouring the aqueous medium or by mechanical agitation, in particular using blades. When agitation stops if necessary, after sufficient time for adsorption of organic pollutants on the son derivative, the sediment sediment at the bottom of the settling tank. The cleaned aqueous medium supernatant can then be removed, in particular by pumping. The sound derivative which adsorbed the phytosanitary products is recovered, in particular by scraping the bottom of the settling basin with a scraper.

With regard to the static decantation in discontinuous mode, reference can be made, by way of illustration, to FIG. 10 below.

The invention also relates to a method of removing organic pollutants comprising: suspending a derivative of its initial, and in particular a lignocellulosic substrate in a liquid medium to be decontaminated contained in a reactor, maintaining suspension of the bran derivative, and in particular of the lignocellulosic substrate by stirring said medium, either by stirring means, in particular pale, or by recirculation loops external to the reactor, until the depollution of said medium by adsorption of pollutants on the derivative of bran and in particular on the lignocellulosic substrate to obtain a liquid medium cleaned up, - stopping the stirring and the overdrawing of the liquid medium cleaned up, possibly the replacement of the bran derivative and in particular of the lignocellulosic substrate having adsorbed the pollutants by a derivative of sound of the same nature as the derivative of its, and in particular the initial lignocellulosic substrate or the elimination of the derivative of bran, and in particular of the lignocellulosic substrate, having adsorbed the pollutants, in particular by overdrawing or scraping said sound derivative, and in particular said lignocellulosic substrate.

With regard to the discontinuous settling in discontinuous mode, reference can be made, by way of illustration, to FIG. 11 below. The reactor used in the above process has a volume of between 10 and 1000 m ³ , and especially between 20 and 500 m ³ .

The mechanical stirring by means of paddle is advantageously carried out at a speed of between 5 to 100 rpm and in particular between 10 to 50 rpm (with a blade 1 meter in diameter).

The suspension of the bran derivative by recirculation loops external to the reactor means that the recirculation rate of the liquid corresponds to a hydraulic retention time (HRT) of 2 to 20 hours (if a reactor is 100 m ³ , pumping from 50m ³ / h to 5 m ³ / h), preferably 5 to 10 h (20 m ³ / h to 10 m ³ / h per 100 m ³ ).

The hydraulic retention time (HRT) is the time required for the renewal of the liquid in the reactor, which depends on the flow rate applied.

The overdrawing of the cleaned liquid medium is in particular carried out by pumping.

By the term "derivative of its initial" is meant a derivative of its which has not been put in the presence of organic pollutants or which has been regenerated.

The subject of the invention is also a process for the removal of organic pollutants comprising: suspending a derivative of bran and in particular a lignocellulosic substrate in a liquid medium to be decontaminated continuously introduced into a reactor,

- maintaining suspended by stirring said liquid medium,

• by means of stirring, especially pale,

• either by recirculation loops external to the reactor or

Or by the rapid and continuous introduction of the liquid medium to be decontaminated in the reactor at its lower part, for a time sufficient for the pollutants to be adsorbed by the bran derivative and in particular by the lignocellulosic substrate,

the recovery of the medium continuously introduced, after adsorption of the pollutants, into a static settling basin, in which the depolluted medium overflows by overflow at the top of the reactor and in which the bran derivative and in particular the lignocellulosic substrate having adsorbed the pollutants sediments,

the recovery of the bran derivative and in particular of the lignocellulosic substrate, which is returned or not to the reactor. With regard to mechanically agitated settling in continuous mode, reference can be made to FIG. 12 for illustrative purposes and to hydraulically agitated settling in continuous mode in FIG. 13.

According to an advantageous embodiment of the process, the flow rate of the medium to be cleaned introduced into the reactor varies from 20 to 10 m / h, for a reactor of 100 m.

By way of example, if adsorption kinetics of less than or equal to 2 h are considered, a hydraulic retention time of 2 h is required. For a reactor of 100 m ³ , the effluent is preferably introduced at a flow rate of less than 50 m ³ / h. It is advantageous to provide 5 to 10 hours of hydraulic retention time (ie for 100 m of reactor, a flow rate of 20 to 10 m / h).

The subject of the invention is also a process for the removal of organic pollutants comprising the use of one or more columns containing a sonic derivative and in particular a lignocellulosic substrate and comprising the following stages: a step of percolation with a derivative of its , and in particular a lignocellulosic substrate, of a liquid medium to be decontaminated by downflow or upflow, allowing the adsorption of pollutants by the bran derivative, and in particular the lignocellulosic substrate, and the recovery of the depolluted medium. According to the embodiment described above, the method comprises:

a step of passing the medium to be decontaminated in a first column containing a sonic derivative, and in particular a lignocellulosic substrate having a saturation coefficient of phytosanitary pollutants greater than 50%, in particular between 75 and 99%, and capable of arresting clogging substances and substances capable of modifying the amphiphilic character of the bran derivative, and in particular of the lignocellulosic substrate contained in the medium to be decontaminated, to obtain a partially depolluted medium,

a second step of passage of the partially depolluted medium obtained in the preceding step in a column containing a son derivative, and in particular a lignocellulosic substrate with a pollutant saturation coefficient of less than 75%, in particular of 10 to 75%, capable of lowering the level of phytosanitary pollutants contained in the environment to be decontaminated to a value of less than approximately 1 μg / l, and in particular of less than 0.1 μg / l, and in particular less than 0.05 μg / l, to obtain a substantially cleansed environment,

optionally a third step of passage of the substantially depolluted medium obtained in the preceding step in a column containing a derivative of its, and in particular a lignocellulosic substrate not initially containing any phytosanitary pollutants and capable of regulating the possible variations, in particular increases in concentrations, of phytosanitary pollutants contained in the medium to be decontaminated, in order to obtain a depolluted medium.

The third step is safety, and the medium that is introduced into this column is already at a phytosanitary product concentration lower than the legislation.

Such a depollution process is a descending percolation process (see FIG. 14 below) or ascending percolation (see FIG. 15 below), depending on whether the medium to be decontaminated is introduced, respectively, by the top or the bottom. of the column, in continuous mode.

According to the embodiment described above, the bran derivative, and in particular the lignocellulosic substrate, is present in an aqueous medium, at a given instant, in the form of a powder having a bulk density of 0.4 (kg / l), at a rate of about 0.01 kg to about 0.02 kg of bran derivative per liter of aqueous medium to be decontaminated.

The subject of the invention is also a process for eliminating organic pollutants, in particular plant protection products contained in an air medium, comprising bringing the sonic derivative into contact with the gas, and in particular the lignocellulosic substrate in the form of a dry solid, for example under form of slabs on floors or walls in confined spaces, filters in contaminated atmosphere extractor systems, or filter cartridges for personal protective equipment such as gas masks.

At the end of the processes defined above, the saturated cereal bran derivative is:

- is regenerated under the action of adequate treatment, to allow the desorption of organic pollutants, for example at a pH below 2. The eluate obtained after desorption of organic pollutants and filtration to recover the derivative of its, is rich in phytosanitary products that can be concentrated in order to send a smaller volume of waste

- be cremated to destroy the phytosanitary, after checking the absence of production of toxic volatile organic compounds. Legend of figures

Figures 1 to 7 show isothermal adsorption results of different plant protection products, depending on different parameters such as time, pH or the concentration of phytosanitary products.

Figures 8 and 9 show comparative test results of the adsorption properties of a lignocellulosic wheat bran substrate and a lignocellulosic substrate of wheat straw.

Figures 10 to 15 illustrate particular embodiments of the method of the invention and more particularly the depollution of aqueous media using sound derivatives.

Figure 1: Kinetics of adsorption of terbumeton on the lignocellulosic substrate of wheat bran.

The lignocellulosic substrate (2 g / l) and terbumeton at a concentration of 10 ^-5 mol / l (ie 56 μg) were placed in 25 ml of water and the adsorption test was carried out at pH 4. 8. Figure 1 gives the percentage of terbumeton adsorbed on the lignocellulosic substrate (ordinates) over time (abscissa expressed in hours).

Figure 2: Kinetics of adsorption of dimethomorph on the lignocellulosic substrate of wheat bran.

The lignocellulosic substrate (2 g / l) and dimethomorph at a concentration of 10 ^" mol / l (ie 969 μg) were placed in 25 ml of water and the adsorption test was carried out at pH 4. 8. Figure 2 gives the percentage of dimethomorph adsorbed on the lignocellulosic substrate (ordinates) over time (abscissa expressed in hours).

Figure 3: Influence of pH on the absorption of terbumeton on the lignocellulosic substrate of wheat bran.

The lignocellulosic substrate (2 g / l) and terbumeton at a concentration of 10 ^'5 mol / l (ie 56 μg) were brought together in 25 ml of water for 2 hours. The adsorption of terbumeton on the lignocellulosic substrate was tested at pH values ranging from 6 to 9. Figure 3 gives the percentage of terbumeton adsorbed on the lignocellulosic substrate (ordinates) as a function of the pH (abscissa). Figure 4: Influence of pH on the adsorption of dimethomorph on the lignocellulosic substrate of wheat bran.

The lignocellulosic substrate (2 g / l) and dimethomorph at a concentration of 10 ^-4 mol / l (ie 969 μg) were brought together in 25 ml of water for 2 hours.The adsorption of dimethomorph on the substrate Lignocellulosic was tested at pHs ranging from 2 to 11. Figure 4 gives the percentage of dimethomorph adsorbed on the lignocellulosic substrate (ordinates) as a function of pH (abscissa).

5A and 5B: Isoproturon (5A) and dimethomorph (5B) adsorption on the lignocellulosic substrate of wheat bran as a function of the initial concentration of plant protection product introduced.

The lignocellulosic substrate (2 g / l) and increasing amounts of isoproturon (5A) and dimethomorph (5B), respectively, were placed in 25 ml of water for 2 hours. The adsorption test was carried out at pH 4.8.

The quantity of phytosanitary product adsorbed in μmol / g of lignocellulosic substrate (ordinates) is given according to the quantity of phytosanitary product initially introduced (abscissa expressed in μmol / g).

Figure 6: Adsorption of terbumeton (6A) and of desethylterbumeton (6B) on the lignocellulosic substrate of wheat bran according to the initial concentration of plant protection product introduced.

The lignocellulosic substrate (2 g / l) and increasing amounts of terbumeton (6A) and desethylbumin (6B) respectively were placed in 25 ml of water for 2 hours. The adsorption test was carried out at pH 4.8.

Figure 7: Kinetics of adsorption of terbumeton on lignocellulosic substrate of wheat bran in a batchwise stirred settling model.

The lignocellulosic substrate (5 g / l) and the terbumeton at a concentration of 43 μg / g of lignocellulosic substrate were placed in 105 L of water. The adsorption test was carried out at pH 4.8. Figure 7 gives the percentage of terbumeton adsorbed on the lignocellulosic substrate (ordinates) over time (abscissa expressed in hours).

Figure 8: Comparison of the adsorption of different crop protection products on lignocellulosic wheat bran substrate relative to the lignocellulosic substrate of wheat straw.

Adsorption experiments were carried out at pH 4.8 on a lignocellulosic substrate of wheat bran (shaded columns) or on a lignocellulosic substrate of wheat straw (white columns).

The lignocellulosic substrate at a concentration of 2 g / 1 was brought into contact with the phytosanitary product, respectively at a concentration of 11.2 mg / g of substrate for terbumeton (TER), 9.9 mg / g for desethylterbumeton ( DET), 8.3 mg / g for isoproturon (ISO) and 11.6 mg / g for dimethomorph (DIM), in a final volume of 25 ml.

The percentage of adsorption (mass of phytosanitary product adsorbed on the mass initially introduced) for each of the plant protection products is shown on the ordinate.

Figure 9: Comparison of Terbumeton adsorption on lignocellulosic wheat bran substrate relative to lignocellulosic substrate of wheat bran at different pH.

Adsorption experiments were carried out, respectively at pH 3, pH 4.8 and pH 6, on a lignocellulosic substrate of wheat bran (shaded columns) or on a lignocellulosic substrate of wheat straw (white columns). The lignocellulosic substrate at a concentration of 2 g / l was placed in the presence of terbumeton at a concentration of 11.2 mg / g of lignocellulosic substrate, in a final volume of 25 ml.

The adsorption percentage (mass adsorbed on the mass initially introduced) of terbumeton is shown on the ordinate.

Figure 10: Static decantation in batch mode

FIG. 10 represents the method of elimination of organic pollutants by static decantation in batch mode.

In step 1, the unsaturated lignocellulosic substrate in phytosanitary products (1) covers the bottom of a settling basin (2) whose surface area ratio height is greater than 1. In step 2, the aqueous medium to be treated (3) is introduced into the settling basin, resulting in suspending the lignocellulosic substrate (4). The polluting products contained in the water and the lignocellulosic substrate are left in contact for a time sufficient to allow the adsorption of the pollutants on the latter. In step 3, the lignocellulosic substrate sediments (5) at the bottom of the settling basin and the treated medium (6) is removed, for example by surface pumping (7) to the level of the substrate. In step 4, the lignocellulosic substrate (8) saturated with phytosanitary products is then recovered by scraping (9) from the bottom of the settling basin.

Figure 11: Agitated settling in discontinuous mode (batch)

Fig. 11 shows the process of removing organic pollutants by batchwise stirred settling.

In step 1, the unsaturated lignocellulosic substrate in phytosanitary products (1) and the aqueous medium to be treated (2) are introduced into the contact reactor (3). In step 2, the lignocellulosic substrate is suspended (4) by stirring the medium, for example with blades (5). The pollutants contained in the water and the lignocellulosic substrate are left in contact by homogeneous agitation for a time sufficient to allow the adsorption of the pollutants on the latter. In step 3, stirring is stopped. After sedimentation of the lignocellulosic substrate (6), the treated medium (7) is removed, for example by surface pumping (8) to the level of the substrate and the substrate is recovered (9).

Figure 12: Mechanically stirred decantation in continuous mode

Figure 12 shows the method of removing organic pollutants by mechanically agitated decantation in continuous mode.

The unsaturated lignocellulosic substrate in phytosanitary products (1) and the aqueous medium to be treated (2) are introduced continuously into the contact reactor (3). The lignocellulosic substrate is suspended (4) by stirring the medium, for example with blades (5). The pollutants contained in the water and the lignocellulosic substrate in suspension are left in contact, with stirring, for a sufficient hydraulic retention time to allow the adsorption of the pollutants on the latter. The medium which continuously overflows from the contact reactor flows into a decanter (6) where the substrate saturated with phytosanitary products (7) sediments continuously. The treated medium is continuously recovered by overflow (8), the hydraulic retention time in the decanter having allowed a optimal sedimentation of the substrate. If the substrate is saturated with phytosanitary products, it is eliminated (9) and if it is not saturated, it is reintroduced into the circuit (10),

Figure 13: Hydraulically agitated settling by continuous upward fluidization

Figure 13 shows the method of removing organic pollutants in hydraulically stirred settling by continuous upward fluidization.

The unsaturated lignocellulosic substrate in phytosanitary products (1) and the aqueous medium to be treated (2) are introduced continuously through the bottom of the contact reactor (3), which causes agitation to suspend the ligno substrate. -cellulosic (4). The pollutants contained in the water and the lignocellulosic substrate in suspension are left in contact with stirring for a sufficient hydraulic retention time to allow the adsorption of the pollutants on the latter. The continuously overflowing medium of the contact reactor flows into a decanter (5) where the substrate saturated with phytosanitary products (6) sediments continuously. The treated medium is continuously recovered by overflow (7), the hydraulic retention time in the decanter having allowed optimal sedimentation of the substrate. If the substrate is saturated with phytosanitary products, it is removed (8) and if it is not saturated, it is reintroduced into the circuit (9).

Figure 14: Downward Percolation in Continuous Mode with Low Load Loss

Fig. 14 shows the continuous downward percolation process with a pressure drop of less than 3 bar.

This method consists in passing a medium containing the organic pollutants in several successive columns (four columns are represented in the figure) containing the lignocellulosic substrate. The latter is at a saturation coefficient of phytosanitary products decreasing from the first to the last column. The medium to be treated is successively introduced from the top of each of the columns.

In step 1, the medium to be treated (1) is introduced into the first column (2) in which the lignocellulosic substrate is almost saturated, between 75% and 99%, phytosanitary products (3). In step 2, the medium that exits after passing through the first column is recovered and introduced into the second column containing a substrate with a phytosanitary saturation coefficient of less than 75% (4). After passage of the medium over several columns to a saturation coefficient of phytosanitary products of less than 75%, the medium is finally introduced in step 3 in a column containing an unsaturated substrate of phytosanitary products (5) and the treated medium is recovered from the bottom of the column (6).

Figure 15: Ascending Percolation (Fluidized Bed) in Continuous Mode

Fig. 15 shows the upwardly percolating process in continuous mode. This method consists of passing the medium containing the organic pollutants in several successive columns (four columns are shown in the figure) containing the lignocellulosic substrate. The latter is at a saturation coefficient of phytosanitary products decreasing from the first to the last column The medium to be treated is successively introduced from the bottom of each of the columns.

In stage I _3, the medium to be treated (1) is introduced into the first column (2) in which the lignocellulosic substrate is almost saturated, between 75% and 99%, with plant protection products (3). In step 2, the medium that exits after passing through the first column is recovered and introduced from the bottom of the second column containing a substrate to a phytosanitary saturation coefficient of less than 75% (4). After passage of the medium over several columns to a saturation coefficient of phytosanitary products of less than 75%, the medium is finally introduced in step 3 in a column containing an unsaturated substrate of phytosanitary products (5) and the treated medium is recovered from the top of the column (6).

Figure 16: Influence of the presence of copper (II) on the adsorption of terbumeton on the lignocellulosic substrate of wheat bran

The lignocellulosic substrate (2 g / l) and terbumeton at a concentration of 10 ^-5 mol / l (ie 2.25 mg) were placed in 25 ml of water, while Figure 16 gives the percentage of adsorbed terbumeton. on the lignocellulosic substrate as a function of the pH (abscissae), in the absence (o) and in the presence (x) of copper (II) (c = 2.10 ^-4 mol / l).

Figure 17: Influence of the presence of polyethoxylated fatty amines (POEA) on the adsorption of terbumeton on the lignocellulosic substrate of wheat bran according to the semi-pilot conditions.

The lignocellulosic substrate (2 g / l) and terbumeton at a concentration of 10 ^-5 mol / l were brought together in 105 l of water, while Figure 17 gives the percentage of terbumeton adsorbed on the lignocellulosic substrate in the absence (O) and in the presence (x) of POEA on the lignocellulosic substrate.

POEA is used at a final concentration of 42.3 μg / l (4.44 mg).

Figure 18 ^' : Measurements of the surface tension of different systems

Figure 18 shows the variation of the surface tension (mN / m) over time (hours) of different systems: (-) water + terbumeton, () water + POEA, (...) water +

RLC, (D) RLC + terbumeton + POEA.

The conditions of the experiment are identical to those given in Figure 17.

Figure 19: Adsorption of terbumeton on a column of lignocellulosic substrate.

FIG. 19 shows the percentage of adsorption of terbumeton (c = 10 ^-5 mol.L ^-1 ) (n) on a lignocellulosic substrate column (V = 21 mL) and the quantity of terbumeton introduced (Δ) and accumulated in column outlet (O) as a function of the volume of solution eluted (in mL).

EXAMPLE 1 Study of the adsorption capacity of phytosanitary products on a lignocellulosic substrate of wheat bran

Material and methods

1. Preparation of the lignocellulosic substrate of wheat bran

A ton of bran is washed in 14.5 tons of hot water at a temperature of 50 ° C. to 80 ^° C. to obtain a de-ionized sound. Alternatively, 1 ton of bran can be washed in 8.5 tons of cold water at a temperature of 10 ^° C. to 20 ^° C. in an acidic medium at pH 1-2, in particular using 70 kg of a solution. 96% H ₂ SO ₄ , to obtain a dephytised (and deodorized) sound.

A solid / liquid separation step is carried out on the press-washed sound, thanks to a twin-screw press, sold by Atlas-Stord, of 5 tonnes / h, provided with 1 mm porosity cages through which the washing water, the two screws of Archimedes having a step which is reduced, thus compressing the liquid / solid mixture against the cages and conveying the marc of sound, désamidonné or dephytisé, pressed towards the exit of solids.

The solid is hydrolyzed in an acidic medium with 40 kg of a 96% pure solution of H ₂ SO ₄ , with 3.8 tonnes of water per wet tonne of ground press, for at least ¹ hour at 130 ^° C. and pH of about 1 to 2. An alkaline treatment of the hydrolyzate obtained is carried out with 33 kg / ton of wet grounds of a solution of Ca (OH) ₂ , to increase the pH to about 3.

The hydrolyzate is then filtered and the solid obtained, the crude lignocellulosic substrate, is rinsed in one to two volumes of cold or hot water and then filtered several times on a filter press, until a residue of dry matter is obtained. between 15 and 40%.

The substrate is then dried on a cylindrical dryer provided with blades stirring the moist product in a hot air stream of 100 to 180 ⁰ C, to obtain a dry matter of between 80 and 99%.

The lignocellulosic substrate is then milled and sieved to a particle size of less than 100 μm.

The lignocellulosic substrate is then treated with potassium hydroxide to eliminate lignin molecules of low molecular weight, in particular of molecular weight less than 1500 Da. These molecules of low molecular weight are eliminated because they can go into solution, becoming then likely to compete with pesticides in the adsorption on the lignocellulosic substrate.

The potash treatment consists of suspending the lignocellulosic substrate in a KOH solution at 10 ^-2 mol / l at a concentration of 100 g of substrate / l, with stirring, the solution obtained is then drained on a sieve of 50 ml. The supernatant recovered is centrifuged in order to recover the visible, but smaller than 50 μm fine particles of lignocellulosic substrate, passed through the sieve and which will be added to the substrate.

The lignocellulosic substrate is suspended at a concentration of 100 g / l in osmosis water with stirring and is then drained on the sieve. The supernatant is centrifuged to recover the lignocellulosic substrate. This washing operation is performed 4 times.

2. Hydration of lignocellulosic substrate

The lignocellulosic substrate, for example 50 mg, is suspended in a vessel containing 10 to 15 ml of distilled water. The suspension is stirred for the time necessary for the hydration of the lignocellulosic substrate, for example for 24 hours. In each adsorption test, a control without lignocellulosic substrate is produced.

3, Adsorption test of the phytosanitary product and copper (II) on the lignocellulosic substrate

The pH of the solution containing the lignocellulosic substrate in suspension is fixed at the desired pH by means of an automatic burette by addition of 0.1 mol.l ^-1 hydrochloric acid or 0.1 mol.l potassium hydroxide. ^"1 .

The phytosanitary product is added to the hydrated lignocellulosic substrate. The volume of the mixture obtained is adjusted to have a final lignocellulosic substrate concentration of 2 g / l. For the study of the influence of the presence of copper (II) on the adsorption of the product plant health, a solution of Cu (NO ₃ ) ₂ at the desired concentration is added simultaneously to the crop protection product, before adjusting the volume of the mixture.

The phytosanitary products tested are dimethomorph (DIM, organochlorine fungicide), isoproturon (ISO ₅ herbicide derived from urea), terbumeton (TER, herbicide derived from triazines) and one of its metabolites desethylterbumeton (DET), of which the formulas are represented below:

dimethomorph isoproturon

terbumeton desethylbumeton

The suspensions containing the phytosanitary product are subjected to stirring for 12 hours, the time required for the sorption equilibrium being less than 2 hours. The sorption equilibrium means that there is no longer any exchange between the molecules in solution and the molecules adsorbed on the surface of the lignocellulosic substrate. At the sorption equilibrium, the maximum of potentially adsorbable phytosanitary product is then adsorbed (under the given conditions). The suspensions are then filtered on a 0.2 μm polyamide micropore filter and the quantity of phytosanitary product in the eluate is assayed.

4. Determination of phytosanitary products

The quantity of phytosanitary product adsorbed on the lignocellulosic substrate is determined by the difference between the introduced concentration and the remaining concentration present in the eluate. Phytosanitary products are determined by high performance liquid chromatography (HPLC) with a diode array detector. The eluent used is an acetonitrile / water mixture in variable proportions depending on the phytosanitary product. The table below presents the conditions of analysis of the different phytosanitary products studied:

Results

The adsorption properties of various phytosanitary products on the lignocellulosic substrate of wheat bran were studied as a function of time, pH and phytosanitary product concentration. The experiments are carried out in suspension in batch mode (closed reactor equilibrium).

1. Kinetic studies

The experiments are carried out at pH 4.8, the natural pH of the lignocellulosic substrate. The natural pH of the lignocellulosic substrate is the pH for which no acid or base has been added. This is the pH measured when the lignocellulosic substrate is only in the presence of water.

Figures 1 and 2 show, respectively, the adsorption kinetics of terbumeton and dimetomorph. In both cases, there is a plateau representing the sorption equilibrium that is reached quickly, in a few hours at most. In both cases, at least 80% of the potentially adsorbable amount is fixed in less than one hour on the lignocellulosic substrate.

These results are very interesting because with 50 mg of lignocellulosic substrate, after 1 hour of contact, 51% of the terbumeton and 43% of the dimetomorph are adsorbed on the lignocellulosic substrate, which corresponds to mass adsorptions of 29 μg and 417 μg, respectively.

The phytosanitary contents found in the water before treatment are most frequently of the order of 0.05 μg / l to a few μg / l. Phytosanitary concentrations higher than a few μg / 1 are only encountered in specific cases, for example during a specific pollution or in the case of effluents from the cleaning of tanks.

The rapid kinetics of adsorption of phytosanitary products on the lignocellulosic substrate confirms the interest of its use for the purpose of depollution of the contaminated media.

Influence of HP

The influence of pH is an important parameter, since water, depending on its origin, can have relatively different pH. The results presented in FIGS. 3 and 4 show that, in the most frequently encountered pH range, namely pHs ranging from 6 to 8, the percentage of plant protection product adsorbed is little or not influenced by this parameter. Thus, for terbumeton, the adsorption percentage is 30% in this pH range, and for dimetomorph, 6.5%.

Adsorption test on the lignocellulosic substrate as a function of the phytosanitary product concentration

The results of the adsorption of phytosanitary products as a function of the quantity initially introduced are reported in FIG. 5A, 5B, 6A and 6B. From these curves, it is possible to determine the maximum amount of phytosanitary product that the lignocellulosic substrate can set for an initial quantity of phytosanitary product.

Thus, according to the curves obtained, for 50 μmol of phytosanitary product introduced per gram of lignocellulosic substrate, the quantities of phytosanitary product adsorbed per gram of lignocellulosic substrate are:

1.0 mg / g (5 μmol / g) for isoproturon, 8.3 mg / g (21 μmol / g) for dimethomorph, 4.8 mg / g (21 μmol / g) for terbumeton and 1.8 mg / g (9 μmol / g) for desethylbumeton.

The quantities of phytosanitary adsorbed are significant and far exceed the quantities found in waters which, in concentrations, vary most frequently between 0.05 μg / 1 and a few μg / 1, and those allowed by the regulations (0.1 μg / 1).

With the exception of dimethomorph, the maximum adsorption on the lignocellulosic substrate could not be determined because of the solubility of the phytosanitary products which does not allow to increase sufficiently their initial concentration. This makes it possible to envisage actual adsorption capacities that are clearly greater than those reported above. As regards dimethomorph, the saturation of the lignocellulosic substrate is reached for a quantity of dimethomorph of 11.3 mg per gram of lignocellulosic substrate.

By way of comparison, the maximum adsorption capacities of the two compounds currently most used for phytosanitary products of the same family are 6 mg / g for activated carbon (wheat straw ashes). and rice) and 30 to 66 mg / g for the modified resins (selective adsorption of a type of phytosanitary).

Influence of the presence of other pollutants: metal cations

Most waters contain a significant amount of metal cations. The influence of their presence on the adsorption properties of the lignocellulosic substrate was studied. For this purpose, an isotherm of adsorption of terbumeton as a function of the pH in the presence of copper (II) was carried out according to the laboratory conditions. By way of example, FIG. 16 represents the adsorption isotherms obtained in the case of terbumeton.

Copper has no influence on plant protection product retention capacities, even at high metal cation concentrations (2.10 ^" mol / l), except for terbumeton, but copper (II) influences the retention capacity of the lignocellulosic substrate vis-à-vis terbumeton is low because the percentage of phytosanitary product retained between pH 6 and 9 is only slightly lower in the absence of copper (II) (FIG. . Furthermore, at a concentration close to natural conditions (2.10 ^"5 mol / 1), copper has no influence on the adsorption of terbumeton.

In other cases, the presence of metal cations, especially copper, iron, can improve the retention properties of the lignocellulosic substrate. Indeed, some phytosanitary products alone, such as amitrole, do not adsorb on the lignocellulosic substrate. However, in solution, it forms a complex with copper (II) which allows the attachment of the phytosanitary product to the surface of the lignocellulosic substrate by the formation of a ternary complex. Other plant protection products such as glyphosate are exalted in the presence of copper (II) for basic pH (Sheals, J., Granstrom, M., Sjôberg, S., Persson, P., J. Colloid Interface ScI, 2003). , 262, 38-47).

It therefore seems that the presence of complexing agents such as the metal cations present in the natural effluents to be treated does not affect the adsorption capacities of the phytosanitary products on the lignocellulosic substrate, except for a possible improvement of the retention capacities. .

Influence of the presence of other organic pollutants

The phytosanitary products marketed contain an active substance and a formulating agent. Formulants are organic pollutants that may compete with plant protection products during adsorption on the lignocellulosic substrate. Thus, the influence of the presence of another organic pollutant, polyethoxylated fatty amines (POEA), has been studied by carrying out the adsorption of terbumeton as a function of time on the lignocellulosic substrate in the presence of POEA according to semi-pilot conditions. (Figure 17). POEA is a formulation agent used in the formulation of Roundup ^® marketed by Monsanto.

This study shows that the retention kinetics of terbumeton is very little modified by the presence of POEA. Indeed, the two curves are almost identical, and the kinetics of adsorption is done in two stages, a fast and a slower one. The sorption equilibrium is reached after 4 hours in both cases. In addition, the amount of phytosanitary product retained on the surface of the lignocellulosic substrate is almost identical in both cases. This shows that the lignocellulosic substrate is a good means of depollution of media contaminated by plant protection products, as it retains the phytosanitary product in the presence of its formulation agent. In this study, the POEA assay was also performed by measuring the surface tension. Figure 18 shows the variation of the surface tension over time of different systems. This kinetic study shows that, during the first hours, the surface tension increases, which corresponds to the adsorption of terbumeton on the lignocellulosic substrate. Then, in an unexplained way, it falls, then finally reaches a plateau as for the retention of terbumeton. The plateau is reached for a value of surface tension quite close to that of the water + lignocellulosic substrate system, which shows that the POEA is retained on the surface of the RLC and is no longer present in solution.

EXAMPLE 2 Comparison of the Adsorption of Different Phytosanitary Products on the Lignocellulosic Substrate of Wheat Bran and Wheat Straw

The methods used are those described in Example 1. The lignocellulosic substrate of wheat straw is extracted in the same manner as the lignocellulosic substrate of wheat bran.

The mass quantities of phytosanitary products per gram of lignocellulosic substrate used for the adsorption tests are as follows: 11.2 mg / g for terbumeton

9.9 mg / g for desethylbumeton

- 8.3 mg / g for isoproturon

11.6 mg / g for dimethomorph.

Results

The adsorption capacity of the lignocellulosic substrate of cereal bran was compared to another lignocellulosic residue derived from wheat straw. The adsorption of terbumeton, desethylterbumeton, isoproturon and dimetomorph on lignocellulosic substrate extracted from wheat bran and wheat straw was evaluated at pH 4.8.

Figure 8 shows the adsorption on each of the two substrates (as a percentage of the quantity of phytosanitary product adsorbed on the amount initially introduced).

For each of the phytosanitary products tested, the lignocellulosic substrate extracted from wheat bran has adsorption capacities of 2 to 5 times greater than that extracted from straw. of wheat. In fact, more than 40% of terbumeton is retained by the lignocellulosic substrate of cereal bran, whereas less than 20% is fixed by the lignocellulosic substrate extracted from the wheat straw. This superiority of the lignocellulosic substrate of cereal bran is much more marked in the case of dimetomorph and isoproturon. Indeed, the lignocellulosic substrate of cereal bran retains nearly five times more phytosanitary product than the lignocellulosic substrate of wheat straw. This shows that the retention capacity of the lignocellulosic substrate extracted from wheat bran is much greater than that of lignocellulosic substrate derived from wheat straw.

The influence of pH on the adsorption on each of the two substrates was also studied. The retention of terbumeton was evaluated on the two substrates at 3 different pH. Figure 9 shows that the adsorption of terbumeton is up to 6 times higher on the lignocellulosic substrate wheat bran compared to the straw.

In conclusion, the adsorption capacity of phytosanitary products on the lignocellulosic substrate extracted from wheat bran is clearly better than that of the lignocellulosic substrate extracted from wheat straw, whatever the pH.

EXAMPLE 3 Adsorption of terbumetonon lignocellulosic substrate of wheat bran by agitated decantation and percolation

Material and method

1. Agitated settling experiments

The lignocellulosic substrate (500 g) obtained from wheat bran is treated with potassium hydroxide, as described in Example 1.

Subsequently, the substrate is suspended in osmosis water at a concentration of 5 g / l (for example, 100 L of water per 500 g of substrate), in a 150 liter vessel provided with a blade having a rotation speed of at least 16 m / min, with stirring for 12 h. The pH of the solution is adjusted to 6 with 50% potassium hydroxide solution in order to perform the experiment in conditions close to the natural environment, even if the pH has no influence on the adsoiption properties of the lignocellulosic substrate.

5 1 of a solution of terbumeton concentration 4,44 mg / 1, or 22.2 mg of terbumeton, are then added into the medium containing the lignocellulosic substrate in suspension to give a mixture. The mixture is stirred for the duration of the experiment.

10 ml of supernatant of the mixture are taken at different times to determine, according to the protocol described in Example 1, the amount of terbemuton remaining in the medium and deduce the amount adsorbed on the lignocellulosic substrate.

2. Percolation experiments

A percolation experiment is performed in a glass column supplied with liquid by a peristaltic pump. The bottom of the column is covered with fine gravel, at least 1 mm in the shortest length, to retain fine particles of lignocellulosic substrate.

The lignocellulosic substrate (100 g) is hydrated in 500 ml of osmosis water to allow it to be placed more easily in the column. The lignocellulosic substrate is treated by passing through the column of 1 1 of a KOH solution at 10 ^-2 mol / l, in order to increase the pH and to perform the experiment at a pH close to natural conditions, even if the pH has no influence on the adsorption properties of the lignocellulosic substrate.The column is then rinsed 4 times with 5 l of osmosis water.The first percolated eluates at the outlet of the column are ironed on the bed of lignocellulosic substrate because they contain fine particles of substrate.

5 1 of a terbumeton solution at 2.25 mg / l, ie 11.25 mg of terbumeton, are introduced into the column. Samples of the collected eluate are taken regularly during the flow of the column to determine the terbumeton concentration of the eluate.

Results For the decantation experiments, after 24 hours, 75% of the quantity of terbumeton introduced is retained on the lignocellulosic substrate (see Figure 7). It is also interesting to note that about 80% of the potentially adsorbable amount is adsorbed in 30 minutes and 95% is adsorbed in less than 4 hours.

On the other hand, the terbumeton residual in the solution, which is 25%, may appear high, but the initial amount of terbumeton is extremely high, by a factor of at least 1000 (mg to μg), compared to concentrations of phytosanitary products found in the natural environment. The experiments are carried out only at high concentrations of terbumeton, because for reasons of threshold detection by HPLC, it is not possible to detect low concentrations of terbumeton by this method. However, for terbumeton concentrations of the order of μg / 1, the percentage of residual terbumeton is less than 5%, according to the theory of adsorption at the liquid-solid interface which states that, in general, the more the amount of adsorbate decreases relative to the amount of adsorbent, the more the percentage of adsorbed product increases.

It is interesting to determine the adsorption capacity of the lignocellulosic substrate in a dynamic mode for treating a large volume of polluted water, but with equipment much less cumbersome than the agitated settling mode, for example.

The results obtained in a first percolation test are shown in the following table:

The term "BV" (Be d Volume) refers to the volume of product passed through the column per bed volume of lignocellulosic substrate. The volume of lignocellulosic substrate is 260 ml in the experiment.

After 16 minutes of elution, the concentration of terbumeton in the 105 ml of eluate collected is 52 μg / 1, which indicates that 99.5% of the initial quantity of terbumeton introduced are retained on the column.

From an eluate volume of 2132 ml, the concentration of terbumeton in the eluate is only 20 μg / 1, which corresponds to about 99.8% adsorption on the lignocellulosic substrate. This value is constant up to an eluate volume of 4692 ml.

As previously, the residual concentration of phytosanitary may seem important, but for the same reasons as the settling experiments, the initial concentration of terbumeton is extremely high, by a factor of at least 1000 (from mg to μg), relative to the concentrations of phytosanitary products encountered in the natural environment and it is not possible to reduce the concentration of terbumeton because of the detection threshold by HPLC.

In a second percolation test, the maximum adsorption capacity of the lignocellulosic substrate was evaluated, by determining from which quantity of terbumeton the column is saturated.

By way of example, FIG. 19 represents the percentage of terbumeton adsorbed and the quantity of terbumeton introduced as a function of the volume of solution eluted. This study shows that up to 3 liters of eluted solution, the lignocellulosic substrate column retains more than 90% of phytosanitary product. The percentage of product retained begins to decrease significantly from 6 liters of eluted solution, which represents a quantity of terbumeton adsorbed 12 mg. In addition, the curve representing the amount of terbumeton at the column outlet indicates that after 6 liters of eluted solution, the residual terbumeton begins to increase slightly.

Then, the percentage of phytosanitary product continues to decrease, but however the lignocellulosic substrate still retains 70% of phytosanitary product introduced after an elution of 10 liters. The experiment was not performed until the column was completely saturated. The objective of this study is primarily applied, that is to say that we seek to know the amount of terbumeton a column of lignocellulosic substrate is able to retain. Thus the column studied is effective up to 8 L of eluted solution and then retains 15 mg of terbumeton. The adsorption capacities of the lignocellulosic substrate are of the same order of magnitude as those obtained in the case of activated carbon. Indeed, Heijman and Hopman (Colloids Surfaces A, Activated carbon filtration in drinking water production: model prediction and new concepts, 1999, 151, 303-310) have shown that a column of activated carbon retains about 90% of atrazine introduced.

From 10 liters, the elution solution is replaced by distilled water in order to see if the terbumeton is desorbed. The percentage of terbumeton continues to decrease which shows that the product is slightly desorbed.

EXAMPLE 4 Adsorption of terbumeton contained in a natural effluent on lignocellulosic substrate of wheat bran by agitated decantation and percolation

Material and method

1. Agitated settling experiments

The lignocellulosic substrate is suspended in water from a natural effluent: the water was taken from a settling basin that collects water from runoff from a catchment area cultivated in vineyards, in the commune of Reuil (Marne, 51). This water contains 0.4 mg / 1 of mineral matter and 20.6 mg / 1 of dissolved organic matter. In order to eliminate large insoluble particles (water lenses, vegetable particles, mineral particles), the effluent is sieved on a curved grid with a porosity of 100 μm.

Then, the lignocellulosic substrate is suspended in the filtered effluent at a concentration of 5 g / l (for example, 100 l of water per 500 g of substrate), in a 150-liter vat equipped with a blade having a rotation speed of at least 16 m / min, with stirring for 12 h. The pH of the solution is adjusted to 6 with a 50% potassium hydroxide solution in order to carry out the experiment in conditions close to the natural environment, even if the pH has no influence on the adsorption properties of the solution. lignocellulosic substrate.

10 ml of supernatant of the mixture are taken at different times to determine, according to the protocol described in Example 1, the amount of terbumeton remaining in the medium and deduce the amount adsorbed on the lignocellulosic substrate.

2. Percolation experiments

The percolation experiments are carried out according to the protocol described in the example

3, replacing the osmosis water used to suspend the lignocellulosic substrate by the filtered effluent obtained as described above.

Results

With regard to settling experiments, after 24 hours, the adsorption of terbumeton on the lignocellulosic substrate is similar to that obtained using osmosis water: 75% of the quantity of terbumeton introduced is retained on the lignocellulosic substrate. It is interesting to note that about 80% of the potentially adsorbable amount is adsorbed in 30 minutes and 95% is adsorbed in less than 4 hours. For practical reasons, only the introduced terbumeton was determined, because the possible residues of plant protection products initially present in the effluent are at a too low concentration to be able to detect them by the method of assay used.

As for the percolation tests, the results are similar to those obtained with osmosis water instead of effluent: more than 99.5% of the quantity of terbumeton introduced is adsorbed on the column. The saturation threshold of the column is not reached with this quantity of terbumeton.

EXAMPLE 5 Adsorption of terbumeton and a phytosanitary product formulation agent on lignocellulosic substrate of wheat bran by agitated decantation and percolation

Material and method

1. Agitated settling experiments

Subsequently, the substrate is suspended in osmosis water at a concentration of 5 g / l (for example, 100 L of water per 500 g of substrate), in a 150 liter vessel provided with a blade having a rotation speed of at least 16 m / min, with stirring for 12 h. The pH of the solution is adjusted to 6 with a 50% potassium hydroxide solution in order to carry out the experiment in conditions close to the natural environment, even if the pH has no influence on the adsorption properties of the solution. lignocellulosic substrate.

Polyethoxylated fatty amines (POEA), a formulating agent used in the formulation of Roundup ^® herbicide marketed by Monsanto, are added in addition to terbumeton, at a rate of 20% of the dry mass thereof.

Thus, 5 liters of a solution of terbumeton of concentration 4.44 mg / l, ie 22.2 mg of terbumeton, and 4.44 mg of POEA (ie 0.89 mg / l), are added in the medium containing the lignocellulosic substrate in suspension to give a mixture. The mixture is stirred for the duration of the experiment.

2. Percolation experiments

3, adding, at the same time as terbumeton, POEA, at the rate of 20% of the dry matter of terbumeton.

Results

With regard to settling experiments, after 24 hours, 70% of the quantity of terbumeton introduced is retained on the lignocellulosic substrate. It is also interesting to note that about 75% of the potentially adsorbable amount is adsorbed in 30 minutes and 90% is adsorbed in less than 4 hours. For practical reasons, only introduced terbumeton has been studied because we do not have analytical methods for assaying POEAs.

The decrease in adsorption reflects a slight competition between POEA and Terbumeton.

As for the percolation tests, the results are similar to those obtained with a solution of terbumeton: more than 99.5% of the quantity of terbumeton introduced are adsorbed on the column. The saturation threshold of the column is not reached with this quantity of terbumeton.

Conclusion

The various studies carried out show that the lignocellulosic substrate extracted from cereal bran is a good product for the depollution of environments contaminated by plant protection products. In fact, the adsorption kinetics of phytosanitary products (terbumeton, terbumeton desethyl, isoproturon and dimetomorph) on the lignocellulosic substrate is rapid, independent of the pH of the medium and the quantity of products retained is very satisfactory. (from 1 to 10 mg per gram of lignocellulosic substrate). In addition, the retention capacity of this biomaterial vis-à-vis phytosanitary products are equal to or even greater than currently used processes (especially activated carbon), but the cost of return lignocellulosic substrate is significantly lower than the latter.

Thus, according to the processes, the lignocellulosic substrate can be used both by the farmer and by the purification plants to clean up environments contaminated with plant protection products.

Claims

1. Use of a cereal bran derivative, containing not more than 10% of material capable of being solubilized, for the removal of organic pollutants, especially phyto-sanitary products contained in a medium to be decontaminated, by adsorption of said pollutants on the derivative cereal bran

2. Use according to claim 1 wherein the bran derivative is selected from, the bran essentially starch-free (its de-ionidized), the bran essentially free of starch and phytic acid (its dephytised), the lignocellulosic substrates derived from hydrolysates of its dehydrated or lignocellulosic substrates derived from the hydrolysates of its dephytised.

3. Use according to one of claims 1 or 2, wherein the cereals are selected from at least one of the following cereals: wheat, oats, barley, buckwheat, millet, sorghum, rice, corn, rye and including plants belonging to the family Poaceae, especially selected from: Triticum sp. (wheat), Zea mays (maize), Oryza sativa (rice), Hordeum vulgare (barley), Secale cereal (rye), Panicum sp. (millet), Sorghum sp. (sorghum), Fagopyrum sp. (buckwheat), Pennisetum sp. (millet), Triticum x Secale (triticale) and Avena sp (oats).

4. Use according to one of claims 1 to 3, wherein the plant protection products belong to the group comprising at least one of the following products: acaricides, bactericides, fungicides, herbicides, nematicides, rodenticides, taupicides, molluscicides, corvicides, fumigants , insecticides.

5. Use according to one of claims 1 to 4, wherein the plant protection products belong to the group comprising at least one of the following products:

, - organophosphorus products, in particular glyphosate, bromophos, malathion,

- organochlorine products, especially dimetomorph,

pyrethroid products, in particular depallethrin, permethrin, fluvanilate, urea derivatives, in particular isoproturon, diflubenzuron, diuron, linuron,

carbamates, especially triallate, carbofuran, triazines, especially termébuton, desethylterébébon, simazine, atrazine, terbutylazine,

carbinols, sulfones and sulfonates, aryloxyacids, amide derivatives: alachlor, metolachlor.

6. Use according to one of claims 1 to 5, wherein the media to be cleaned up are selected from among the following media:

- liquids, in particular aqueous and / or organic liquids, and in general the aqueous media which are designated under the generic names of aquifers, and which could have come into contact with phytosanitary products,

- aerial, in particular an atmosphere contaminated with aerosol sprays of plant protection agents or confined atmospheres,

- solids, in particular soils, in particular cultivated or uncultivated soils, sheltered or otherwise from precipitation and greenhouses, particularly confined.

The use according to one of claims 1 to 6, wherein the bran derivative is a lignocellulosic substrate from its container about 10% to about 50% lignin and about 50% to about 90% cellulose.

8. Use according to one of claims 1 to 7, wherein the bran derivative, and in particular the lignocellulosic substrate, is amphiphilic and contains active sites capable of establishing hydrophilic, hydrophobic, electrostatic and ionic interactions. with organic pollutants.

9. Use according to one of claims 1 to 8, wherein the bran derivative, and in particular the lignocellulosic substrate, contains fatty acids having from 6 to 28 carbon atoms, simultaneously enhancing the hydrophilic character of the derivative of its, and especially lignocellulosic substrate, through the carboxylic groups, ethers and hydroxyls, and the hydrophobic character, through the aliphatic chains and aromatic rings.

10. Use according to one of claims 1 to 9, wherein the bran derivative is a lignocellulosic substrate and has the following characteristics: it consists of approximately 51% carbon, approximately 7% hydrogen and approximately 42% oxygen;

the concentration of acidic surface sites corresponding to the carboxylic sites is about 0.65 mmol / g and at the phenolic sites is about 0.40 mmol / g;

the density of acidic sites is approximately 3 sites / nm ² .

11. Use according to one of claims 1 to 10, wherein the lignocellulosic substrate is as obtained by acid-base treatment of cereal bran to eliminate starch, hemicellulose and proteins, and in particular by subjecting the cereal bran, optionally ground, to the process comprising the following steps: a step of washing the bran, either with hot water or with cold water in an acidic medium, to obtain, respectively, the deodidized washed bran or its washed dephytised, followed by a liquid-solid separation carried out on the washed sound to eliminate the soluble (organic acids with short chains, sugars, minerals, soluble proteins) and the starch of the flour, to obtain respectively the deamidated or dephytised sound;

a step of acid hydrolysis of the dehydrated or dephytised sound with the aid of an acid, for hydrolyzing the hemicelluloses present in simple sugars, as well as any residual starch in glucose and proteins not previously solubilized in amino acids to obtain a hydrolyzate of its deionized or dephytised, consisting of a liquid phase of soluble products, which phase is rich in pentoses (arabinose and xylose) from hemicelluloses, and a solid phase, consisting essentially of raw lignocellulosic substrate ; a step of alkaline treatment of the hydrolyzate of its deionized or of its dephytised using a base for neutralizing the anions of the acid used in the acid hydrolysis step, and to obtain after filtration a solid, the raw lignocellulosic substrate;

a possible step of rinsing the crude lignocellulosic substrate to obtain a rinsed lignocellulosic substrate;

a possible step of drying the lignocellulosic substrate rinsed to obtain the lignocellulosic substrate rinsed and dried; and a possible step of grinding the lignocellulosic substrate rinsed and dried to obtain the lignocellulosic substrate rinsed and dried in powder form.

12. Use according to one of claims 1 to 11, wherein the bran derivative, and in particular the lignocellulosic substrate is in combination with at least one of the following elements:

- lignocellulosic residue of cereal straw,

- clay,

- Activated carbon, especially macroporous resins or gels, cationic or anionic ion exchange, adsorbent resins, stearic exclusion resins, zeolites, silica, especially diatomaceous earth, especially kieselguhr.

13. Use according to one of claims 1 to 12, wherein the bran derivative, and in particular the lignocellulosic substrate is in the form of powder having a particle size less than about 2 mm, in particular from about 20 microns to about 100. μm, in particular from about 50 μm to about 100 μm.

14. Use according to one of claims 1 to 13, wherein the bran derivative, and in particular the lignocellulosic substrate is suspended in an aqueous medium, and in particular at a rate of about 0.01 to about 50 g. / 1, especially from about 1 to about 10 g / 1, aqueous medium to be cleaned.

15. Use according to one of claims 1 to 14, wherein the phytosanitary product is solubilized in aqueous medium to be cleaned, and in particular at a rate of about 0.05 to about 100 μg / 1 of aqueous medium to be cleaned.

16. Use according to one of claims 1 to 13 or 15 wherein the bran derivative, and in particular the lignocellulosic substrate, is present in an aqueous medium, at a given instant, in the form of a powder having an apparent density of 0. , 4 (kg / l), at a rate of about 0.01 kg to about 0.02 kg of bran derivative per liter of aqueous media to be decontaminated.

17. Use according to one of claims 1 to 13, wherein the bran derivative, and in particular the lignocellulosic substrate is in the form of agglomerated powder forming a dry solid.

18. Use according to one of claims 1 to 13 or 17 wherein the phytosanitary product is present in the form of gas, in particular at a rate of about 1 ng / m ³ to about 10 μg / m ³ and / or in solution in droplets of aqueous medium, especially at a rate of 0.05 to 100 μg / 1 of water in suspension, especially after the use of aerosols in the air environment to be cleaned up.

19. Use according to one of claims 1 to 18, wherein the phytosanitary product is formulated with a wetting agent, a surfactant-type dispersant, an adhesive, an antifoam, a buffer, an anti-rebound polymer, an oil. , a nitrogen fertilizer, a dye, a humectant, a UV absorber, an anti-drift.

20. Use according to one of claims 1 to 19, wherein the adsorption of phytosanitary products on the bran derivative, and in particular on the lignocellulosic substrate is from about 1 to about 20 mg / g and in which the quantity of residual phytosanitary products in the medium to be decontaminated after adsorption of a part of the phytosanitary products initially present in the medium to be decontaminated, on the bran derivative, and in particular on the lignocellulosic substrate, is less than 1 μg / l, in particular less than 0.1 μg / 1, in particular less than 0.05 μg / l.

21. A method for removing organic pollutants, in particular phytosanitary products contained in a medium to be decontaminated, comprising a step of contacting the medium to be cleaned with a cereal bran derivative, and in particular a lignocellulosic substrate, for a sufficient time. for adsorption of pollutants on the derivative of bran, and in particular on the lignocellulosic substrate.

22. Method according to claim 21, in which the phytosanitary products are defined in one of claims 4, 5, 15, 18 or 19 and in which the bran derivative, and in particular the lignocellulosic substrate, is defined in claims 2, 3, 7 to 14, 16 or 17.

23. Method according to one of claims 21 or 22, comprising the suspension of the son derivative, and in particular the lignocellulosic substrate in the water of a water settling tank containing pollutants, by contacting water containing pollutants with the bran derivative, and in particular with the lignocellulosic substrate deposited in a basin, the surface / height ratio of which is advantageously greater than 1, in particular between 1 and 100,

- the possible agitation of the water,

the recovery of the bran derivative and in particular of the lignocellulosic substrate having sedimented for a time sufficient to adsorb the pollutants, for example by pumping the supernatant medium constituted by the water situated on the bran derivative and in particular on the ligno substrate. -cellulosic, up to the level of the derivative of its and in particular the lignocellulosic substrate.

24. Method according to one of claims 21 or 22, comprising: the suspension of a son derivative, and in particular of an initial lignocellulosic substrate in a liquid medium to be decontaminated contained in a reactor,

the suspension in suspension of the bran derivative, and in particular of the lignocellulosic substrate, by stirring the said medium, either by stirring means, in particular pale, or by recirculation loops external to the reactor, until the depollution of said medium by adsorption of pollutants on the bran derivative and in particular on the lignocellulosic substrate to obtain a liquid medium which has been cleaned up,

stopping the agitation and overdrawing the liquid medium that has been cleaned up,

possibly replacing the sound derivative, and in particular the lignocellulosic substrate having adsorbed the pollutants, with a bran derivative, and especially a lignocellulosic substrate of the same nature as the bran derivative, and in particular the lignocellulosic substrate. initial or removal of the derivative of bran, and in particular the lignocellulosic substrate having adsorbed the pollutants, in particular by overdrawing or scraping said son derivative, and in particular said lignocellulosic substrate,

or

suspending a sound derivative, and in particular a lignocellulosic substrate in a liquid medium to be decontaminated, introduced continuously into a reactor,

maintaining the suspension by stirring of said liquid medium, or by stirring means, in particular a blade, • either by recirculation loops external to the reactor or

Or by the rapid and continuous introduction of the liquid medium to be decontaminated in the reactor at its lower part, for a time sufficient for the pollutants to be adsorbed by the bran derivative, and in particular the lignocellulosic substrate,

the recovery of the medium continuously introduced, after adsorption of the pollutants, into a static settling basin, in which the bran derivative, and in particular the lignocellulosic substrate, having adsorbed the pollutants sediments, the recovery of the bran derivative, and in particular of the substrate lignocellulosic, which is returned or not in the reactor.

25. Method according to one of claims 21 or 22, comprising the use of one or more columns containing a son derivative, and in particular a lignocellulosic substrate and comprising the following steps:

a step of percolation with a derivative of bran, and in particular a lignocellulosic substrate, of a liquid medium to be decanted by downflow or upflow, allowing adsorption of pollutants by the bran derivative, and in particular the substrate; lignocellulosic,

- and the recovery of the cleaned up medium,

and including,

a step of passage of the medium to be decontaminated in a first column containing a son derivative, and in particular a lignocellulosic substrate having a saturation coefficient of phytosanitary pollutants greater than 50%, in particular between 75 and 99% and susceptible to stopping clogging substances and substances capable of modifying the amphiphilic character of the bran derivative, and in particular of the lignocellulosic substrate contained in the medium to be decontaminated, to obtain a partially depolluted medium,

a second step of passage of the partially depolluted medium obtained in the preceding step in a column containing a bran derivative, and in particular a lignocellulosic substrate with a pollutant saturation coefficient of less than 75%, especially from 10 to 75%; %, likely to lower the rate of phytosanitary pollutants contained in the environment to be decontaminated to a value lower than about 1 μg / 1, and especially less than 0.1 μg / 1, and especially less than 0.05 μg / 1 to obtain a substantially cleansed medium,

optionally a third step of passage of the substantially depolluted medium obtained in the preceding step in a column containing a son derivative, and in particular a lignocellulosic substrate not initially containing any phytosanitary pollutants and capable of regulating any variations, especially increases concentrations, phytosanitary pollutants contained in the environment to be cleaned, to obtain a cleansed environment.

26. Method according to one of claims 21 or 22, for the removal of organic pollutants, especially plant protection products contained in an air medium, comprising contacting the gas derivative of the bran, and in particular the lignocellulosic substrate in form. dry solid, for example in the form of slabs on floors or walls in confined spaces, filters in contaminated atmosphere extractor systems, or filter cartridges for personal protective equipment such as gas masks.