Classifications

• • 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.

Landscapes

• 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)

Applications Claiming Priority (3)

Publications (1)

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• 1999
  • 1999-11-03 FR FR9914015A patent/FR2801046B1/fr not_active Expired - Fee Related
• 2000
  • 2000-10-31 WO PCT/FR2000/003040 patent/WO2001032567A1/fr not_active Application Discontinuation
  • 2000-10-31 KR KR1020027005755A patent/KR20020065507A/ko not_active Application Discontinuation
  • 2000-10-31 CN CNB00815144XA patent/CN1261375C/zh not_active Expired - Fee Related
  • 2000-10-31 US US10/129,078 patent/US6734326B1/en not_active Expired - Fee Related
  • 2000-10-31 RU RU2002114340A patent/RU2235691C2/ru not_active IP Right Cessation
  • 2000-10-31 PL PL00355204A patent/PL355204A1/xx not_active Application Discontinuation
  • 2000-10-31 EP EP00974620A patent/EP1230174A1/fr not_active Ceased
  • 2000-10-31 SK SK632-2002A patent/SK6322002A3/sk unknown
  • 2000-10-31 CA CA 2389696 patent/CA2389696A1/fr not_active Abandoned
  • 2000-10-31 BR BR0015475A patent/BR0015475A/pt not_active Application Discontinuation
  • 2000-10-31 JP JP2001534727A patent/JP2003512932A/ja active Pending
  • 2000-11-01 AR ARP000105759 patent/AR026322A1/es unknown
• 2001
  • 2001-01-15 TW TW89123107A patent/TW499400B/zh not_active IP Right Cessation

Non-Patent Citations (1)

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