EP1230174A1 - Method for treating aqueous effluents containing peroxidized compounds - Google Patents

Method for treating aqueous effluents containing peroxidized compounds

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Publication number
EP1230174A1
EP1230174A1 EP00974620A EP00974620A EP1230174A1 EP 1230174 A1 EP1230174 A1 EP 1230174A1 EP 00974620 A EP00974620 A EP 00974620A EP 00974620 A EP00974620 A EP 00974620A EP 1230174 A1 EP1230174 A1 EP 1230174A1
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EP
European Patent Office
Prior art keywords
effluents
compounds
effluent
anaerobic
deperoxidation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP00974620A
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German (de)
French (fr)
Inventor
Frédéric BAUD-GRASSET
Agnès PILAS-BEGUE
Serge Veracini
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Rhodia Polyamide Intermediates SAS
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Rhodia Polyamide Intermediates SAS
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Publication of EP1230174A1 publication Critical patent/EP1230174A1/en
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/28—Anaerobic digestion processes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E50/00—Technologies for the production of fuel of non-fossil origin
    • Y02E50/30—Fuel from waste, e.g. synthetic alcohol or diesel

Definitions

  • the present invention relates to a process for purifying aqueous effluents containing in particular peroxide compounds. It relates more particularly to a process for the purification of aqueous effluents comprising a process for anaerobic biological decomposition of the compounds contained in the effluent.
  • the effluents which can be treated by the process of the invention are in particular those produced by the processes of oxidation of organic compounds.
  • the process for the oxidation of hydrocarbons such as cyclohexane is used on a large scale.
  • the transformation of cyclohexane into cyclohexanol / cyclohexanone is implemented for the manufacture of adipic acid, a large chemical intermediate for the manufacture of numerous products such as in particular polyamides, polyesters, polyurethanes.
  • This manufacture of cyclohexanol / cyclohexanone is carried out in large industrial units producing annually up to a few hundred thousand tonnes and generating large volumes of effluents.
  • anaerobic wastewater purification methods in particular those containing more than 1 g / l of degradable COD, are preferred to aerobic purification methods.
  • anaerobic processes produce useful and valuable products such as methane.
  • the energy required for the implementation of an anaerobic process is less than that used in an aerobic process.
  • anaerobic purification processes produce significantly less sludge than aerobic processes.
  • One of the aims of the present invention is to propose a process for treating effluents originating from the manufacture of a cyclohexanol / cyclohexanone mixture and more particularly processes for the oxidation of olefins to alcohols and / or acetones by a biological purification process. anaerobic.
  • the invention provides a method for anaerobic biological purification of aqueous effluent containing peroxide compounds and biodegradable organic compounds.
  • This process is characterized in that it consists in: treating the effluents to transform the peroxide compounds into oxidized compounds, - purifying the aqueous effluents deperoxidized in an anaerobic biological treatment process by decomposition into methane and carbon dioxide.
  • the Applicant has found that the aqueous effluents after elimination by transformation of the peroxide compounds can be purified effectively and without damage to the enzymes and the bacteria in a conventional anaerobic biological treatment process, with production of methane and carbon dioxide.
  • the aqueous effluents containing organic compounds and peroxide compounds must be treated in a step called "deperoxidation” which consists in heating them to a temperature higher than 20 ° C, preferably included between 50 ° C and 90 ° C, in the presence of a deperoxidation catalyst.
  • This catalyst is advantageously a metallic compound.
  • the transition metal compounds can be used, such as ferric compounds, for example.
  • the concentration of catalyst is between 0.5 and
  • the deperoxidation reaction is controlled by chemical dosing of the peroxides. This reaction is continued to obtain a mMol / l peroxide concentration of less than 5 mMol / l, advantageously less than 2 mMol / l. According to another advantageous characteristic of the invention, it may be favorable to treat by the process of biological purification of effluents whose COD is less than 30 g / l. This concentration can also be obtained by diluting with effluents from the processes for the synthesis of chemical compounds, before or after the deperoxidation step. Furthermore, after deperoxidation, the pH of the effluents is adjusted to a value between 5.5 and 6.5. This adjustment is made by adding a basic soluble compound such as sodium hydroxide, basic sodium salts or the like.
  • a basic soluble compound such as sodium hydroxide, basic sodium salts or the like.
  • this adjustment of the pH can be carried out by adding acid compounds, if the pH of the effluents after deperoxidation is basic.
  • the effluent thus treated is fed into the anaerobic bioconversion process which generally comprises a first stage of transformation of the organic compounds into light carboxylic acids such as acetic and propionic acid then a second stage of digestion during which the organic compounds are broken down into methane and carbon dioxide.
  • the process of the invention is particularly applicable to the treatment of effluents from processes for the oxidation of olefins to alcohols and ketones and more particularly to processes for the oxidation of cyclohexane to give a mixture of cyclohexanol / cyclohexanone which by a new oxidation leads for example to the synthesis of adipic acid.
  • / ketone has a concentration of the order of 100 to 1000 mg / l of peroxide compounds expressed as cyclohexyl hydroperoxide, as well as carboxylic acids, alcohols and the like, and a COD of the order of 5 to 50 g / l .
  • This effluent is treated in a first deperoxidation step, after optionally diluting with water.
  • the transformation rate of the peroxides is adjusted to obtain a final concentration of peroxides compatible with the anaerobic bioconversion treatment, indicated above.
  • this deperoxidation step is advantageously carried out in a reactor
  • the effluent thus deperoxidized and having a pH compatible with the bioconversion treatment is fed into a first digester.
  • the organic compounds are converted into monocarboxylic acid compounds such as acetic and propionic acid. This step is also called the "acetogenesis" step.
  • the medium thus treated is fed into a second digester to transform the organic compounds mainly into methane. This step is called methanogenesis.
  • the gas collected at this stage consists of at least 80% by volume of CH and can therefore be recovered as fuel.
  • the process of the invention has made it possible to reduce the COD of the starting effluent by more than 70%, or even more than 80%.
  • BOD Bio Oxygen Demand
  • the effluents treated according to the process of the invention can be supplied to wastewater treatment plants, or discharged directly.
  • This process generates aqueous effluents containing many organic compounds such as adipic, glutaric, succinic, acetic, formic acids, cyclohexanol, cyclohenanone, for example.
  • the effluents also include peroxides expressed as cyclohexyl hydroperoxide (HPOCH) in a relatively large amount, of the order of a few mMol / l. These effluents have a COD of between approximately 5 and 20 g / l.
  • the invention proposes to treat these effluents before feeding them into the biological process.
  • the aqueous effluent from the process for manufacturing a cyclohexanol / cyclohexanone mixture, formed by the collection of different process effluents, is heated in a first reactor at a temperature of 60 ° C for 24 hours.
  • a solution of ferric chloride is added to obtain a concentration of 2 mg / l expressed by weight of iron.
  • the effluent is cooled to a temperature of 37 ° C. and then neutralized by adding a sodium hydroxide solution to obtain a pH of between 5.5 and 6 5.
  • Calcium is added in the form of oxide at a concentration between 20 and 200 mg of calcium per liter of effluent.
  • the nutrients are mainly phosphorus and nitrogen added respectively in the form of ammonia and phosphoric acid.
  • the trace elements are, for example, cobalt, nickel, manganese salts.
  • the effluent is fed into the digesters of a UASB process with a closed loop circulation of the effluent, the effluent leaving the digesters is advantageously recycled in the deperoxidation reactor.
  • the COD transformation yield is approximately 83%.
  • the gas recovered at the outlet of the digesters is a mixture of methane and CO 2 at 77% by volume in methane.
  • the concentrations of carboxylic acids and peroxides in the withdrawn effluent are below the detection limits.

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  • Life Sciences & Earth Sciences (AREA)
  • Microbiology (AREA)
  • Water Supply & Treatment (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)
  • Removal Of Specific Substances (AREA)
  • Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The invention concerns a method for purifying aqueous effluents containing in particular peroxidized compounds. More particularly, it concerns a method for purifying aqueous effluents comprising an anaerobic biological decomposition of compounds contained in the effluents. The effluents are treated, prior to their anaerobic biological decomposition, in a deperoxidizing step to reduce the peroxide concentration and prevent harmful effects of said compounds on the enzymes or bacteria.

Description

Procédé de traitement d'effluents aqueux contenant des composés peroxydes Process for treating aqueous effluents containing peroxide compounds
La présente invention concerne un procédé de purification d'effluents aqueux contenant notamment des composés peroxydes. Elle concerne plus particulièrement un procédé de purification d'effluents aqueux comprenant un procédé de décomposition biologique anaérobie des composés contenus dans l'effluent.The present invention relates to a process for purifying aqueous effluents containing in particular peroxide compounds. It relates more particularly to a process for the purification of aqueous effluents comprising a process for anaerobic biological decomposition of the compounds contained in the effluent.
Les effluents pouvant être traités par le procédé de l'invention sont notamment ceux produits par les procédés d'oxydation de composés organiques. Parmi ces procédés, le procédé d'oxydation d'hydrocarbures comme le cyclohexane est exploité à grande échelle. Ainsi, la transformation du cyclohexane en cyclohexanol/cyclohexanone est mise en œuvre pour la fabrication de l'acide adipique, grand intermédiaire chimique pour la fabrication de nombreux produits comme notamment les polyamides, polyesters, polyuréthannes. Cette fabrication de cyclohexanol/cyclohexanone est réalisée dans des unités industrielles importantes produisant annuellement jusqu'à quelques centaines de millier de tonnes et générant des volumes importants d'effluents. Les contraintes imposées pour la protection de l'environnement demandent que ces effluents soient traités, notamment pour diminuer la Demande Chimique en Oxygène (DCO). La réduction de la DCO d'effluents aqueux est mise en œuvre depuis très longtemps, par de nombreux procédés dont des procédés de traitement biologiques par des enzymes.The effluents which can be treated by the process of the invention are in particular those produced by the processes of oxidation of organic compounds. Among these processes, the process for the oxidation of hydrocarbons such as cyclohexane is used on a large scale. Thus, the transformation of cyclohexane into cyclohexanol / cyclohexanone is implemented for the manufacture of adipic acid, a large chemical intermediate for the manufacture of numerous products such as in particular polyamides, polyesters, polyurethanes. This manufacture of cyclohexanol / cyclohexanone is carried out in large industrial units producing annually up to a few hundred thousand tonnes and generating large volumes of effluents. The constraints imposed for the protection of the environment demand that these effluents be treated, in particular to reduce the Chemical Oxygen Demand (COD). The reduction of the COD of aqueous effluents has been implemented for a very long time, by numerous methods including methods of biological treatment with enzymes.
Ces traitements biologiques se classent principalement en trois catégories, à savoir les procédés de purification aérobie, anoxique et les procédés de purification anaérobie. Toutefois, il est connu que les procédés de purification anaérobie des eaux usées, notamment celles contenant plus de 1 g/l de DCO dégradable, sont préférés aux procédés de purification aérobie. En effet, les procédés anaérobies produisent des produits utiles et valorisâmes tels que le méthane. De plus, l'énergie nécessaire pour la mise en œuvre d'un procédé anaérobie est inférieure à celle utilisée dans un procédé aérobie. En outre, les procédés de purification anaérobie produisent une quantité de boues nettement plus faible que les procédés aérobies.These biological treatments mainly fall into three categories, namely aerobic, anoxic purification processes and anaerobic purification processes. However, it is known that anaerobic wastewater purification methods, in particular those containing more than 1 g / l of degradable COD, are preferred to aerobic purification methods. In fact, anaerobic processes produce useful and valuable products such as methane. In addition, the energy required for the implementation of an anaerobic process is less than that used in an aerobic process. In addition, anaerobic purification processes produce significantly less sludge than aerobic processes.
Toutefois, les procédés de purification anaérobie ne peuvent être utilisés pour traiter tous les effluents aqueux car les enzymes utilisées sont sensibles et peuvent être détruites par de nombreux composés. La demanderesse a ainsi constaté que le traitement d'effluents aqueux produits par le procédé de transformation du cyclohexane dans la synthèse du mélange cyclohexanol/cyclohexanone par un procédé anaérobie peut conduire à une destruction des enzymes. L'utilisation d'un tel procédé apparaissait donc impossible.However, anaerobic purification methods cannot be used to treat all aqueous effluents because the enzymes used are sensitive and can be destroyed by many compounds. The Applicant has thus found that the treatment of aqueous effluents produced by the process of transformation of cyclohexane in the synthesis of the mixture cyclohexanol / cyclohexanone by an anaerobic process can lead to the destruction of enzymes. The use of such a process therefore appeared impossible.
Un des buts de la présente invention est de proposer un procédé de traitement des effluents provenant de la fabrication d'un mélange cyclohexanol/cyclohexanone et plus particulièrement des procédés d'oxydation d'oléfines en alcools et/ou acétones par un procédé de purification biologique anaérobie.One of the aims of the present invention is to propose a process for treating effluents originating from the manufacture of a cyclohexanol / cyclohexanone mixture and more particularly processes for the oxidation of olefins to alcohols and / or acetones by a biological purification process. anaerobic.
En effet, la demanderesse a observé que ces effluents contiennent différents composés organiques et des composés peroxydes. Elle a constaté également que ces composés peroxydes ont un effet toxique sur les enzymes ou bactéries utilisées dans les procédés de purification biologique.Indeed, the Applicant has observed that these effluents contain different organic compounds and peroxide compounds. She also found that these peroxide compounds have a toxic effect on the enzymes or bacteria used in biological purification processes.
A cet effet, l'invention propose un procédé de purification biologique anaérobie d'effluent aqueux contenant des composés peroxydes et des composés organiques biodégradables. Ce procédé se caractérisé en ce qu'il consiste à : traiter les effluents pour transformer les composés peroxydes en composés oxydés, - purifier les effluents aqueux déperoxydés dans un procédé de traitement biologique anaérobie par décomposition en méthane et dioxyde de carbone. La demanderesse a trouvé que les effluents aqueux après élimination par transformation des composés peroxydes peuvent être purifiés efficacement et sans dommage pour les enzymes et les bactéries dans un procédé de traitement biologique anaérobie usuel, avec production de méthane et gaz carbonique.To this end, the invention provides a method for anaerobic biological purification of aqueous effluent containing peroxide compounds and biodegradable organic compounds. This process is characterized in that it consists in: treating the effluents to transform the peroxide compounds into oxidized compounds, - purifying the aqueous effluents deperoxidized in an anaerobic biological treatment process by decomposition into methane and carbon dioxide. The Applicant has found that the aqueous effluents after elimination by transformation of the peroxide compounds can be purified effectively and without damage to the enzymes and the bacteria in a conventional anaerobic biological treatment process, with production of methane and carbon dioxide.
Une description générale de ces traitements biologiques anaérobies est, par exemple, donnée dans une communication présentée par P.L. Me Carty à la Seconde Conférence Internationale sur la Digestion Anaérobique le 7/09/1981 à Travemunde - Allemagne sous le titre "100 ans de traitement anaérobique". Pour le traitement des effluents contenant principalement des composés organiques solubles, un procédé de bioconversion a été développé sous l'appellation "Upflow Anaerobic Sludge Blanket" (UASB).A general description of these anaerobic biological treatments is, for example, given in a communication presented by PL Me Carty to the Second International Conference on Anaerobic Digestion on 7/09/1981 in Travemunde - Germany under the title "100 years of anaerobic treatment ". For the treatment of effluents containing mainly soluble organic compounds, a bioconversion process has been developed under the name "Upflow Anaerobic Sludge Blanket" (UASB).
Un tel procédé est décrit dans de nombreuses publications. On peut citer par exemple, - "Upflow Sludge Blanket Processes", 3ème Symposium International sur la Digestion Anaérobique, 1983, Cambridge de G. Lettinga, et al.Such a method is described in numerous publications. We can cite for example, - "Upflow Sludge Blanket Processes", 3 rd International Symposium on Anaerobic Digestion, 1983, Cambridge by G. Lettinga, et al.
- "Anaerobic of Raw Domestic Servage" de G. Lettinga, et al. Dans Biotechnology and Bioengineering Vol XXV, pp 1701-1723, 1983. Selon l'invention, les effluents aqueux contenant des composés organiques et des composés peroxydes doivent être traités dans une étape appelée "dépéroxydation" qui consiste à les chauffer à une température supérieure à 20°C, de préférence comprise entre 50°C et 90°C, en présence d'un catalyseur de dépéroxydation. Ce catalyseur est avantageusement un composé métallique.- "Anaerobic of Raw Domestic Servage" by G. Lettinga, et al. In Biotechnology and Bioengineering Vol XXV, pp 1701-1723, 1983. According to the invention, the aqueous effluents containing organic compounds and peroxide compounds must be treated in a step called "deperoxidation" which consists in heating them to a temperature higher than 20 ° C, preferably included between 50 ° C and 90 ° C, in the presence of a deperoxidation catalyst. This catalyst is advantageously a metallic compound.
Comme composés métalliques convenables, les composés des métaux de transition peuvent être utilisés, comme les composés ferriques, par exemple. Avantageusement, la concentration en catalyseur est comprise entre 0,5 etAs suitable metal compounds, the transition metal compounds can be used, such as ferric compounds, for example. Advantageously, the concentration of catalyst is between 0.5 and
100 ppm exprimé en poids de métal.100 ppm expressed by weight of metal.
La réaction de dépéroxydation est contrôlée par dosage chimique des peroxydes. Cette réaction est poursuivie pour obtenir une concentration en mMol/l en peroxyde inférieure à 5 mMol/l, avantageusement inférieure à 2 mMol/l. Selon une autre caractéristique avantageuse de l'invention, il peut être favorable de traiter par le procédé de purification biologique des effluents dont la DCO est inférieure à 30 g/l. Cette concentration peut être également obtenue par dilution avec de l'eau des effluents issus des procédés de synthèse de composés chimiques, avant ou après l'étape de dépéroxydation. Par ailleurs, après dépéroxydation, le pH des effluents est ajusté à une valeur comprise entre 5,5 et 6,5. Cet ajustement est réalisé par addition d'un composé soluble basique tel que la soude, les sels basiques de sodium ou analogues.The deperoxidation reaction is controlled by chemical dosing of the peroxides. This reaction is continued to obtain a mMol / l peroxide concentration of less than 5 mMol / l, advantageously less than 2 mMol / l. According to another advantageous characteristic of the invention, it may be favorable to treat by the process of biological purification of effluents whose COD is less than 30 g / l. This concentration can also be obtained by diluting with effluents from the processes for the synthesis of chemical compounds, before or after the deperoxidation step. Furthermore, after deperoxidation, the pH of the effluents is adjusted to a value between 5.5 and 6.5. This adjustment is made by adding a basic soluble compound such as sodium hydroxide, basic sodium salts or the like.
Toutefois, cet ajustement du pH peut être réalisé par addition de composés acides, si le pH des effluents après dépéroxydation est basique. L'effluent ainsi traité est alimenté dans le procédé de bioconversion anaérobie qui comprend généralement une première étape de transformation des composés organiques en acides carboxyliques légers tels que l'acide acétique et propionique puis une seconde étape de digestion au cours de laquelle les composés organiques sont décomposés en méthane et gaz carbonique. Le procédé de l'invention s'applique notamment aux traitements d'effluents provenant des procédés d'oxydation des oléfines en alcools et cétones et plus particulièrement aux procédés d'oxydation du cyclohexane pour donner un mélange de cyclohexanol/cyclohexanone qui par une nouvelle oxydation conduit par exemple, à la synthèse de l'acide adipique. L'effluent aqueux à traiter, issu de ce prodécé de fabrication d'un mélange alcoolHowever, this adjustment of the pH can be carried out by adding acid compounds, if the pH of the effluents after deperoxidation is basic. The effluent thus treated is fed into the anaerobic bioconversion process which generally comprises a first stage of transformation of the organic compounds into light carboxylic acids such as acetic and propionic acid then a second stage of digestion during which the organic compounds are broken down into methane and carbon dioxide. The process of the invention is particularly applicable to the treatment of effluents from processes for the oxidation of olefins to alcohols and ketones and more particularly to processes for the oxidation of cyclohexane to give a mixture of cyclohexanol / cyclohexanone which by a new oxidation leads for example to the synthesis of adipic acid. The aqueous effluent to be treated, from this prodecé for manufacturing an alcohol mixture
/cétone présente une concentration de l'ordre de 100 à 1000 mg/l de composés peroxydes exprimée en hydroperoxyde de cyclohexyle, ainsi que des acides carboxyliques, des alcools et autres, et une DCO de l'ordre de 5 à 50 g/l./ ketone has a concentration of the order of 100 to 1000 mg / l of peroxide compounds expressed as cyclohexyl hydroperoxide, as well as carboxylic acids, alcohols and the like, and a COD of the order of 5 to 50 g / l .
Cet effluent est traité dans une première étape de dépéroxydation, après éventuellement une dilution avec de l'eau. Le taux de transformation des peroxydes est ajusté pour obtenir une concentration finale en peroxydes compatibles avec le traitement de bioconversion anaérobie, indiqué précédemment. Dans un mode de réalisation de l'invention cette étape de dépéroxydation est avantageusement réalisée dans un réacteurThis effluent is treated in a first deperoxidation step, after optionally diluting with water. The transformation rate of the peroxides is adjusted to obtain a final concentration of peroxides compatible with the anaerobic bioconversion treatment, indicated above. In one embodiment of the invention, this deperoxidation step is advantageously carried out in a reactor
L'effluent ainsi deperoxydé et présentant un pH compatible avec le traitement par bioconversion est alimenté dans un premier digesteur. Dans ce premier digesteur, les composés organiques sont convertis en composés acides monocarboxyliques tels que l'acide acétique et proprionique. Cette étape est également appelée l'étape "d'acétogénèse".The effluent thus deperoxidized and having a pH compatible with the bioconversion treatment is fed into a first digester. In this first digester, the organic compounds are converted into monocarboxylic acid compounds such as acetic and propionic acid. This step is also called the "acetogenesis" step.
Le milieu ainsi traité est alimenté dans un second digesteur pour transformer les composés organiques principalement en méthane. Cette étape est appelée méthanogénese. Le gaz recueilli à cette étape est constitué d'au moins 80 % en volume de CH et peut donc être valorisé comme combustible.The medium thus treated is fed into a second digester to transform the organic compounds mainly into methane. This step is called methanogenesis. The gas collected at this stage consists of at least 80% by volume of CH and can therefore be recovered as fuel.
Le procédé de l'invention- a permis de diminuer la DCO de l'effluent de départ de plus de 70 %, voir plus de 80 %.The process of the invention has made it possible to reduce the COD of the starting effluent by more than 70%, or even more than 80%.
De même, la DBO (Demande Biologique en Oxygène) a été diminuée d'au moins 90 %.Likewise, BOD (Biological Oxygen Demand) has been reduced by at least 90%.
En conséquence, les effluents traités selon le procédé de l'invention peuvent être alimentés dans des stations d'épuration des eaux usées, ou évacués directement.Consequently, the effluents treated according to the process of the invention can be supplied to wastewater treatment plants, or discharged directly.
D'autres avantages, détails de l'invention apparaîtront plus clairement au vu des exemples donnés ci-dessous uniquement à titre indicatif. Parmi les grands procédés industriels, l'oxydation du cyclohexane en un mélange cyclohexanol/cyclohexanone est mis en œuvre à grande échelle.Other advantages, details of the invention will appear more clearly in the light of the examples given below only for information. Among the major industrial processes, the oxidation of cyclohexane to a cyclohexanol / cyclohexanone mixture is carried out on a large scale.
Ce procédé génère des effluents aqueux contenant de nombreux composés organiques tels que les acides adipique, glutarique, succinique, acétique, formique, du cyclohexanol de la cyclohenanone, par exemple. Les effluents comprennent également des peroxydes exprimés en hydroperoxyde de cyclohexyle (HPOCH) en quantité relativement importante, de l'ordre de quelques mMol/l. Ces effluents présentent une DCO compris entre environ 5 et 20 g/l.This process generates aqueous effluents containing many organic compounds such as adipic, glutaric, succinic, acetic, formic acids, cyclohexanol, cyclohenanone, for example. The effluents also include peroxides expressed as cyclohexyl hydroperoxide (HPOCH) in a relatively large amount, of the order of a few mMol / l. These effluents have a COD of between approximately 5 and 20 g / l.
Un traitement de ces effluents dans un procédé de bioconversion anaérobie, selon un procédé UASB, ne peut être réalisé car la biomasse peut devenir inactive très rapidement.Treatment of these effluents in an anaerobic bioconversion process, according to a UASB process, cannot be carried out because the biomass can become inactive very quickly.
Pour permettre un tel traitement, l'invention propose de traiter ces effluents avant leur alimentation dans le procédé biologique.To allow such treatment, the invention proposes to treat these effluents before feeding them into the biological process.
Dans l'exemple illustré, l'effluent aqueux provenant du procédé de fabrication d'un mélange cyclohexanol/cyclohexanone, formé par le rassemblement de différents effluents du procédé, est chauffé dans un premier réacteur à une température de 60°C pendant 24 heures. Pour favoriser la conversion des peroxydes, une solution de chlorure ferrique est ajoutée pour obtenir une concentration de 2 mg/l exprimé en poids de fer.In the example illustrated, the aqueous effluent from the process for manufacturing a cyclohexanol / cyclohexanone mixture, formed by the collection of different process effluents, is heated in a first reactor at a temperature of 60 ° C for 24 hours. To promote the conversion of peroxides, a solution of ferric chloride is added to obtain a concentration of 2 mg / l expressed by weight of iron.
Après que la concentration en peroxyde ait atteinte un niveau inférieur à 1 mMol/l, l'effluent est refroidi à une température de 37°C puis neutralisé par addition d'une solution de soude pour obtenir un pH compris entre 5,5 et 6,5.After the peroxide concentration has reached a level below 1 mMol / l, the effluent is cooled to a temperature of 37 ° C. and then neutralized by adding a sodium hydroxide solution to obtain a pH of between 5.5 and 6 5.
Pour permettre une meilleure bioconversion, il est avantageux d'ajouter du calcium des nutriments et des oligoéléments, au milieu. Cette addition peut être réalisée avant l'étape de dépéroxydation.To allow better bioconversion, it is advantageous to add nutrient calcium and trace elements in the middle. This addition can be carried out before the deperoxidation step.
Le calcium est ajouté sous forme d'oxyde à une concentration comprise entre 20 et 200 mg de calcium par litre d'effluent.Calcium is added in the form of oxide at a concentration between 20 and 200 mg of calcium per liter of effluent.
Les nutriments sont principalement le phosphore et l'azote ajoutés respectivement sous forme d'ammoniaque et d'acide phosphorique.The nutrients are mainly phosphorus and nitrogen added respectively in the form of ammonia and phosphoric acid.
Les oligoéléments sont par exemple des sels de cobalt, nickel, manganèse.The trace elements are, for example, cobalt, nickel, manganese salts.
L'effluent est alimenté dans les digesteurs d'un procédé UASB avec une circulation en boucle fermée de l'effluent, l'effluent sortant des digesteurs est avantageusement recyclé dans le réacteur de dépéroxydation.The effluent is fed into the digesters of a UASB process with a closed loop circulation of the effluent, the effluent leaving the digesters is advantageously recycled in the deperoxidation reactor.
Une partie des effluents sortant des digesteurs est soutirée. Le rendement de transformation de la DCO est de 83 % environ. Le gaz récupéré en sortie des digesteurs est un mélange de méthane et CO2 à 77 % en volume en méthane. Les concentrations en acides carboxyliques et peroxydes dans l'effluent soutiré sont inférieures aux limites de détection.Part of the effluents leaving the digesters is withdrawn. The COD transformation yield is approximately 83%. The gas recovered at the outlet of the digesters is a mixture of methane and CO 2 at 77% by volume in methane. The concentrations of carboxylic acids and peroxides in the withdrawn effluent are below the detection limits.
Ces résultats ont été obtenus avec un flux d'effluent entrant de 8 l/h et un flux d'effluent sortant de 8 l/h pour un débit de gaz biomasse de 6,72 l/h. L'installation a fonctionné correctement pendant la durée de l'essai qui a été de plusieurs semaines. These results were obtained with an incoming effluent flow of 8 l / h and an outgoing effluent flow of 8 l / h for a biomass gas flow rate of 6.72 l / h. The installation functioned correctly during the test period which was several weeks.

Claims

REVENDICATIONS
1. Procédé de traitement d'effluents aqueux contenant notamment des composés peroxydes et des composés organiques biodégradables, caractérisé en ce qu'il consiste à ;1. Process for treating aqueous effluents containing in particular peroxide compounds and biodegradable organic compounds, characterized in that it consists of;
- traiter les effluents pour transformer les composés peroxydes en composés oxydés,- treat the effluents to transform the peroxide compounds into oxidized compounds,
- traiter les effluents dépéroxydés dans un procédé de purification biologique anaérobie par transformation en méthane et dioxyde de carbone.- treat the deperoxidized effluents in an anaerobic biological purification process by transformation into methane and carbon dioxide.
2. Procédé selon la revendication 1 , caractérisé en ce que l'étape de dépéroxydation est réalisée par un chauffage de l'effluent à une température supérieure à 20°C, en présence d'un catalyseur.2. Method according to claim 1, characterized in that the deperoxidation step is carried out by heating the effluent to a temperature above 20 ° C, in the presence of a catalyst.
3. Procédé selon la revendication 2, caractérisé en ce que le catalyseur est au moins un composé d'un élément métallique choisi dans le groupe comprenant des composés des métaux de transition.3. Method according to claim 2, characterized in that the catalyst is at least one compound of a metallic element chosen from the group comprising compounds of transition metals.
4. Procédé selon l'une des revendications précédentes, caractérisé en ce que le pH des effluents dépéroxydés est ajusté à une valeur comprise entre 5,5 et 6,5, avant alimentation dans le procédé de traitement biologique anaérobie.4. Method according to one of the preceding claims, characterized in that the pH of the deperoxidized effluents is adjusted to a value between 5.5 and 6.5, before feeding in the anaerobic biological treatment process.
5. Procédé selon l'une des revendications précédentes, caractérisé en ce que l'effluent aqueux provient d'un procédé d'oxydation d'oléfines en alcools et/ou cétones.5. Method according to one of the preceding claims, characterized in that the aqueous effluent comes from a process for the oxidation of olefins to alcohols and / or ketones.
6. Procédé selon la revendication 5, caractérisé en ce que le procédé d'oxydation est le procédé d'oxydation de cyclohexane en cyclohexanol/cyclohexanone.6. Method according to claim 5, characterized in that the oxidation process is the oxidation process of cyclohexane to cyclohexanol / cyclohexanone.
7. Procédé selon l'une des revendications 5 ou 6, caractérisé en ce que les effluents provenant du procédé de dépéroxydation sont dilués avec de l'eau pour obtenir une teneur en peroxyde inférieure à 1 mMol/l exprimée en hydropéroxyde de cyclohexyle. 7. Method according to one of claims 5 or 6, characterized in that the effluents from the deperoxidation process are diluted with water to obtain a peroxide content of less than 1 mMol / l expressed as cyclohexyl hydroperoxide.
EP00974620A 1999-11-03 2000-10-31 Method for treating aqueous effluents containing peroxidized compounds Ceased EP1230174A1 (en)

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FR9914015 1999-11-03
FR9914015A FR2801046B1 (en) 1999-11-03 1999-11-03 PROCESS FOR TREATING AQUEOUS EFFLUENTS CONTAINING PEROXIDE COMPOUNDS
PCT/FR2000/003040 WO2001032567A1 (en) 1999-11-03 2000-10-31 Method for treating aqueous effluents containing peroxidized compounds

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PL355204A1 (en) 2004-04-05
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US6734326B1 (en) 2004-05-11
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CA2389696A1 (en) 2001-05-10
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TW499400B (en) 2002-08-21
AR026322A1 (en) 2003-02-05

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