Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
  • C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
  • C02F1/56—Macromolecular compounds
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
  • C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
  • C02F1/5245—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents using basic salts, e.g. of aluminium and iron
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
  • C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
  • C02F1/547—Tensides
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F11/00—Treatment of sludge; Devices therefor
  • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
  • C02F11/14—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents
  • C02F11/148—Combined use of inorganic and organic substances, being added in the same treatment step
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
  • C02F2103/26—Nature of the water, waste water, sewage or sludge to be treated from the processing of plants or parts thereof
  • C02F2103/28—Nature of the water, waste water, sewage or sludge to be treated from the processing of plants or parts thereof from the paper or cellulose industry
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
  • C02F2103/32—Nature of the water, waste water, sewage or sludge to be treated from the food or foodstuff industry, e.g. brewery waste waters

Definitions

• the present invention relates to a new composition which can be used in particular for conditioning sludge prior to its dewatering operation.
• sludge The treatment of waste water, urban or industrial, in particular by biological means, leads to the production of sludge.
• This sludge generally undergoes a mechanical dewatering operation (in particular filtration (for example filter press, belt filter), centrifugation), before being transported to a site of discharge, agricultural spreading or incineration.
• filtration for example filter press, belt filter
• centrifugation the mechanical dewatering operation
• sludge from the paper industry represents a very large part of the industrial sludge produced.
• These sludges from the paper industry like those from the food industry, include, on the one hand, sludges of a biological nature (that is to say from a treatment of waste water by biological), and, on the other hand, sludge of a non-biological nature generally formed, in particular in the case of the paper industry, by sludge of physico-chemical origin or fibrous sludge containing mineral fillers, cellulose, possibly coating latex.
• the sludge to be treated consists mainly of water in which biomass is dispersed.
• the treatments therefore aim to concentrate the dry matter as much as possible and to remove the water.
• the current sludge treatment methods are distinct according to the water / biomass separation technique chosen (filter press, belt filter, centrifuge ...)). In addition, they generally require the successive addition of several reagents; it indeed proves difficult to formulate, in a single composition and at significant concentrations, these different reagents, without leading to the formation of gels which can prove detrimental in terms of fluidity to the corresponding mixtures.
• the object of the present invention is to propose a new composition which can be used effectively in the conditioning of sludge, making it possible in particular to increase their dryness, that is to say to increase the dry extracts obtained during the subsequent dewatering operation.
• the invention also aims to provide a universal composition, that is to say that can be used indifferently for the treatment of sludge prior to one or the other of the dewatering techniques mentioned above.
• composition according to the invention preferably has the advantage of not being subject to the gelling phenomenon mentioned above.
• the main object of the present invention is a composition, usable for conditioning sludge, obtained by mixing (reaction) of at least one aqueous solution containing at least one cationic polyelectrolyte and at least one mineral cation of greater or equal charge to 2 with at least one aqueous solution containing at least one surfactant, preferably anionic or amphoteric.
• the subject of the invention is also a composition, usable for the conditioning of sludges, obtained by mixing (reaction) of at least one aqueous solution containing at least one cationic polyelectrolyte with at least one aqueous solution containing at least one inorganic filler cation greater than or equal to 2 and at least one aqueous solution containing at least one surfactant, preferably anionic or amphoteric.
• compositions which can be used for the conditioning of sludge being in the form of an aqueous solution comprising at least one mineral cation with a charge greater than or equal to 2, at least one cationic polyelectrolyte and at least one surfactant -active, preferably anionic or amphoteric.
• the mineral cation has a charge greater than or equal to 2. It is usually chosen from g 2+ , AI 34 " , Fe 3+ , La 3+ , Zr 4+ and their polymerized forms when they exist. Preferably, said cation mineral is Al 3+ or one of its polymerized forms. In general, the mineral cation is used in non-polymerized form.
• This mineral cation is usually in the form of a water-soluble salt. Mention may be made, as water-soluble salts, of chlorides, nitrates, sulfates and acetates.
• a soluble salt is used, free of the nitrogen element, which makes it possible to overcome any problems linked to its presence.
• a chloride is used.
• the mineral cation can then be in the form of an aluminum chloride or one of its polymerized forms; more preferably, it then takes the form of an aluminum chloride.
• the amount of mineral cation used is preferably between 0.05 and 2 moles, in particular between 0.49 and 1.8 moles, per kg of composition.
• the pH of the solution can be adjusted to prevent precipitation of the corresponding mineral salt. This adjustment is within the competence of those skilled in the art.
• the cationic polyelectrolyte is preferably of high molecular weight, in particular of molecular weight of at least 1.10 6 .
• Said cationic polyelectrolyte advantageously has a molecular weight of 1.10 6 to 20.10 6 , in particular from 1.10 6 to 10.10 6 .
• the cationic polyelectrolyte used can be in a linear form or, preferably, in a branched form; it has in fact been noted that the ramifications generally have a beneficial effect on the kinetics of coagulation and flocculation.
• Polyacrylamides, polyethylene oxides, polyvinylpyrrolidones, and also polymers of natural origin, such as starch and its derivatives or gum such as guar gum, are particularly suitable as cationic polyelectrolyte, insofar as they are cationic.
• the cationic polyelectrolyte is a polyacrylamide.
• Said polyacrylamide can be cationic up to 100% in charge and, preferably, between 0.1 and 25%, for example between 0.1 and 15%, in charge.
• the cationic polyacrylamide can be chosen from copolymers of polyacrylamide with cationic monomers or polyacrylamides modified according to the Mannich reaction.
• cationic polyacrylamide copolymers mention may be made of acrylamide / halide copolymers, preferably diallyldialkylammonium chloride, diaminoalkylmethacrylate / acrylamide copolymers and dialkylaminoalkylmethacrylate / acrylamide copolymers, the alkyl group preferably being C 1 -C 6 .
• the amount of cationic polyelectrolyte used is preferably at most 10%, in particular 0.1 to 6%, by weight of the composition.
• the cationic polyelectrolyte is a polyacrylamide copolymer, and preferably a polyacrylamide / diallyldimethylammonium chloride copolymer, in particular with a molecular weight of the order of 3.10 6 . It is then more preferably associated with an aluminum chloride in the composition.
• the mineral cation with a charge greater than or equal to 2 for example in the case of aluminum chloride
• the cationic polyelectrolyte for example in the case of a high molecular weight polyacrylamide
• the molar ratio (mineral cation of charge greater than or equal to 2) / (cationic polyelectrolyte) is between 1.10 2 and 8.10 6 in particular between 1.10 3 and 8.10 6 .
• a polyacrylamide / aluminum weight ratio of between 0.01 and 15 is preferably used , more particularly between 0.1 and 10; this ratio can be for example between 0.2 and 6, in particular between 0.25 and 4.5.
• the surfactant used in the invention is preferably anionic or amphoteric.
• this surfactant is anionic. Its non-ionic part (which can be formed of a hydrocarbon chain with character hydrophobic and, optionally, of a polyalkoxylated chain of hydrophilic nature, in particular polyethoxylated) may for example have an HLB value ("Hydrophilic / Lipophilic Balance") of at most 10, especially at most 8, or even at most 4.
• HLB value Hydrophilic / Lipophilic Balance
• the surfactant is preferably a surfactant which remains inert with respect to the mineral cation of charge greater than or equal to 2.
• This surfactant makes it possible to provide a hydrophobic function, in particular with respect to the application medium.
• water-soluble surfactants can be used as surfactant agent in the composition
• the water-soluble lecithins may be cited, sucrose esters, fatty acid esters (including Tweens ®), polyoxyethylene alkylamide, the triglyceride sulfates, alkyl sulfates (including sodium dodecyl sulfate (SDS)), alkyl ether sulfates, alkyl sulfonates, alkylamine salts, fatty amines, lipoamino acids, modified polyesters, silicone polymeric surfactants .
• the amount of surfactant used is preferably between 0.005 and 0.5 mole, in particular between 0.005 and 0.3 mole, per kg of composition; it can for example be between 0.01 and 0.2 mole, in particular between 0.01 and 0.1 mole, per kg of composition.
• the composition according to the invention can be prepared by mixing at least one aqueous solution containing at least one cationic polyelectrolyte with at least one aqueous solution containing at least one mineral cation of charge greater than or equal to 2 and at least one aqueous solution containing at least one surfactant.
• the pHs of the three solutions are such, or adjusted (for example by adding an acid solution, in particular hydrochloric acid)) so that the pH of the composition according to the invention is preferably less than 2 , in particular equal to 1 ⁇ 0.2.
• the composition according to the invention is advantageously prepared by mixing at least one aqueous solution A containing at least one cationic polyelectrolyte and at least one mineral cation of charge greater than or equal to 2 with at least one aqueous solution B containing at least a surfactant.
• the aqueous solution A is obtained by adding, generally with stirring, the cationic polyelectrolyte to an aqueous solution containing said mineral cation; the aqueous solution then obtained is generally kept under stirring until the viscosity stabilizes.
• the aqueous solution B is usually prepared by mixing the surfactant in solid form with water.
• the pH of the aqueous solution A and that of the aqueous solution B are such, or adjusted (for example by adding an acid solution, in particular hydrochloric acid)) so that the pH of the composition according to the invention is preferably less than 2, in particular equal to 1 ⁇ 0.2.
• the pH of the aqueous solution B used is, for example, understood or adjusted to a value between 1, 3 and 1, 9.
• the aqueous solution A generally provides the largest part (for example at least 80%, in particular at least 90%) of the total volume of water contained in the composition according to the invention.
• the mixtures are generally carried out between 10 and 75 ° C, for example at room temperature, and with stirring.
• the preparation conditions are such that the composition according to the invention is in the form of a homogeneous solution, in particular monophasic.
• the compositions according to the invention find a particularly advantageous application in the chemical conditioning of sludge, in particular of sludge from sewage treatment plants or wastewater, urban or industrial: its incorporation in the sludge, which can be subjected beforehand to an anaerobic digestion treatment, allows them to be structured in such a way that the water contained in these sludges is better exuded during the following dehydration operation.
• the efficiency of the mechanical dehydration operation such as filtration or centrifugation can thus be improved, the volumes produced after this dehydration being reduced by obtaining a cake of high dryness.
• the amount of composition according to the invention used during the conditioning of a sludge is such that it generally corresponds from 0.05 to 3 times, preferably from 0.1 to 2 times, the amount of theoretical cationic charge necessary to neutralize the amount of anionic charge of the sludge to be treated; in other words, the quantity of this composition used is such that it has, in absolute value, a cationicity generally equal from 0.05 to 3 times, preferably from 0.1 to 2 times, the anionicity of the sludge to be treated.
• the composition according to the invention can be diluted before use.
• compositions according to the invention are especially suitable in the case of sludge from the paper industry, or from the food industry, and containing, on the one hand, sludge of biological nature, and, on the other hand , sludge of a non-biological nature (physico-chemical sludge or fibrous sludge).
• the products constituted by sludge of biological nature and by that of non-biological nature are often incompatible.
• the sludge of biological nature usually exhibits a dissimilar, even divergent, behavior from that of other sludge of a different nature, when all of this sludge undergoes conditioning and / or dewatering treatment. It has been found that, in general, these biological sludges have a slow sedimentation rate, give rise to fermentation reactions and their dehydration is not easy.
• the invention also aims to provide a process for dewatering sludge from the paper industry or sludge from the food industry, these sludges containing sludge of biological nature and sludge of nature non-biological, process in which said sludge of biological nature is pretreated separately with at least one composition according to the invention, then mixed after said pretreatment with sludge of non-biological nature, the mixture of sludges thus formed then being subjected (possibly after another conditioning step) to a dehydration operation.
• the composition according to the invention can be used in the treatment of aqueous media, for example waste water or industrial aqueous effluents, and more particularly in the clarification of waste water of urban or industrial origin. It can also be used for the detoxification of effluents loaded with polluting species (in particular arsenates, chromates, plumbs) and for the decantation of port or lagoon vessels. It can be used as an aid in the filtration of mineral oxides or in the processing or papermaking processes. It can also be used for mineral processing.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Hydrology & Water Resources (AREA)
• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Separation Of Suspended Particles By Flocculating Agents (AREA)
• Treatment Of Sludge (AREA)

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• 2001
  • 2001-03-23 FR FR0104511A patent/FR2824752B1/fr not_active Expired - Fee Related
• 2002
  • 2002-03-25 EP EP02720080A patent/EP1373149A1/de not_active Withdrawn
  • 2002-03-25 WO PCT/FR2002/001032 patent/WO2002076894A1/fr not_active Application Discontinuation

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