Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F9/00—Multistage treatment of water, waste water or sewage
• • 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
  • C02F1/02—Treatment of water, waste water, or sewage by heating
  • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
• • 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
  • C02F1/26—Treatment of water, waste water, or sewage by extraction
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2101/00—Nature of the contaminant
  • C02F2101/30—Organic compounds
  • C02F2101/32—Hydrocarbons, e.g. oil
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2101/00—Nature of the contaminant
  • C02F2101/30—Organic compounds
  • C02F2101/34—Organic compounds containing oxygen
• • 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

Definitions

• This invention relates to the purification of water produced during Fischer-Tropsch synthesis for which synthesis a variety of carbonaceous materials are used as feedstock.
• the applicant is aware of processes for the synthesis of water from a carbonaceous feedstock, such as natural gas and coal, which processes also produce hydrocarbons.
• Fischer-Tropsch process of which the largest product is water and, to a lesser extent, hydrocarbons including olefins, paraffins, waxes, and oxygenates.
• hydrocarbons including olefins, paraffins, waxes, and oxygenates.
• the products from the Fischer-Tropsch process may be processed further, for example by hydroprocessing, to produce products including synthetic crude oil, olefins, solvents, lubricating, industrial or medicinal oil, waxy hydrocarbons, nitrogen and oxygen containing compounds, motor gasoline, diesel fuel, jet fuel and kerosene.
• Lubricating oil includes automotive, jet, turbine and metal working oils.
• Industrial oil includes well drilling fluids, agricultural oils and heat transfer fluids.
• carbonaceous feedstocks In certain areas where carbonaceous feedstocks are to be found, water is in short supply and a relatively costly commodity. Also, environmental concerns prevent the disposal of polluted water derived from the Fischer-Tropsch process into natural water ways and the sea thereby presenting a case for the production and recovery of useable water at the source of the carbonaceous feedstocks.
• the carbonaceous feedstocks typically include coal and natural gas that are converted to hydrocarbons, water and carbon dioxide during Fischer-Tropsch synthesis. Naturally, other carbonaceous feedstocks such as, for example, methane hydrates found in marine deposits, can also be used.
• the water produced during the Fischer-Tropsch is purified in accordance with the present invention, it is typically subjected to preliminary separation aimed at isolating a water-enriched stream from the Fischer-Tropsch products.
• the preliminary separation process includes condensing the gaseous product from the Fischer-Tropsch reactor and separating it in a typical three-phase separator.
• the three streams exiting the separator are: a tail gas, a hydrocarbon condensate including mainly hydrocarbons in the C 5 to C 2 o range and a reaction water stream containing dissolved oxygenated hydrocarbons and suspended hydrocarbons.
• reaction water stream is then separated using a coalescer that separates the reaction water stream into a hydrocarbon suspension and a water-rich stream.
• the coalescer is capable of removing hydrocarbons from the reaction water stream to a concentration of between 10 ppm and 1000 ppm, typically 50 ppm.
• the water-enriched stream thus obtained forms the feedstock for the method according to the present invention and will be denoted in this specification by the term "Fischer-Tropsch reaction water”.
• the composition of the water-enriched stream or reaction water is largely dependent on the catalyst metal used in the Fischer-Tropsch reactor and the reaction conditions (e.g. temperature, pressure) employed.
• the Fischer-Tropsch reaction water can contain oxygenated hydrocarbons including aliphatic, aromatic and cyclic alcohols, aldehydes, ketones and acids, and to a lesser extent aliphatic, aromatic and cyclic hydrocarbons such as olefins and paraffins.
• the Fischer-Tropsch reaction water may also contain small quantities of inorganic compounds including metals from the Fischer-Tropsch reactor, as well as nitrogen and sulphur containing species that originate from the feedstock.
• a process for the production of purified water from Fischer-Tropsch reaction water which process includes at least the steps of: a) a primary treatment stage comprising an equilibrium staged separation process having at least one stage for removing at least a fraction of non-acid oxygenated hydrocarbons from the Fischer-Tropsch reaction water to produce a primary water enriched stream; b) a secondary treatment stage comprising liquid-liquid extraction for removing at least a fraction of organic acids from at least a portion of the primary water enriched stream to produce a secondary water enriched stream; c) a tertiary treatment stage comprising biological treatment for removing at least a fraction of acidic oxygenated hydrocarbons from at least a portion of the secondary water enriched stream to produce a tertiary water enriched stream; and d) a quartic treatment stage comprising solid-liquid separation for removing at least some solids from at least a portion of the tertiary water enriched stream.
• purified water is to be interpreted as meaning an aqueous stream having a COD of between 20 and 500 mg/1, a pH of between 6,0 and 9,0, a suspended solids content of less than 250 mg/1 and a total dissolved solids content of less than 600 mg/1.
• the non-acid oxygenated hydrocarbons are typically selected from the group including: alcohols, ketones, and aldehydes, and are more specifically selected from the group including: acetaldehyde, propionaldehyde, butyraldehyde, acetone, methyl propyl ketone, methanol, ethanol, propanol, butanol, pentanol, hexanol, and heptanol.
• the acidic oxygenated hydrocarbons are typically selected from the group including: formic acid, acetic acid, propionic aid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, and octanoic acid.
• a number of equilibrium staged separation processes are suitable for use in the primary treatment stage. Such processes may include conventional distillation processes typically used in the refining and petrochemical industry as well as solvent extraction using either conventional liquid solvents or liquefied gases.
• Fischer-Tropsch reaction water When distillation is used as the primary treatment stage, the bulk of the non-acid oxygenated hydrocarbons contained in the Fischer-Tropsch reaction water are removed, leaving predominantly mono-carboxylic acids (e.g. acetic acid, propionic acid) and optionally trace quantities of non-acid compounds.
• mono-carboxylic acids e.g. acetic acid, propionic acid
• Fischer-Tropsch reaction water that has undergone primary treatment is known as Fischer-Tropsch acid water.
• the overheads from distillation may be recovered and worked-up to products, or may be used for fuel or as an energy source.
• the primary treatment stage may include degassing of the Fischer-Tropsch reaction water before further processing to remove compounds having a very low boiling point and dissolved gases from the Fischer-Tropsch reaction water.
• Fischer-Tropsch reaction water originating from HTFT iron catalyst processes which water has undergone primary treatment has limited application due to the relatively high concentrations (> 1 % by mass) of organic acids remaining in the Fischer-Tropsch acid water, and further treatment of the water is required.
• Fischer-Tropsch reaction water originating from cobalt-based LTFT processes which water has undergone primary treatment contains significantly lower organic acid concentrations ( ⁇ 0.1 % by mass) and can therefore, following neutralization, be released to the environment if sufficient dilution is available and discharge standards permit.
• This primary water enriched stream may also have limited application as process water.
• the liquid-liquid extraction technique used during the secondary treatment stage may be differential contacting or stagewise contacting.
• the differential contacting technique may include using equipment selected from the group including: spray columns, packed columns, rotating disc contactors and Da Laval contactors, or equivalent contactors.
• the stagewise contacting technique may include using equipment selected from the group including: mixer settlers, perforated plate columns and controlled cycling columns.
• the solvent used during step b) may be selected from a group of water insoluble solvents having an affinity for acids, said group including: alkyl ethers, ethyl acetate, alkyl phosphene oxides, and alkyl amides.
• Step b) typically yields an organic acid enriched extract stream and a water enriched raffinate stream or secondary water enriched stream.
• a mixed hydrocarbon or interface stream containing C4+ hydrocarbons , solvent and Fischer - Tropsch acid water may also be generated. This hydrocarbon stream can be incinerated, send to biological treatment or worked-up to recover the heavier acids.
• the extract stream may be refined and/ or worked-up to recover the solvent. Conventional distillation is typically used for solvent recovery.
• the solvent thus obtained may be recycled to step b) or it may be combined with suitable streams produced during the Fischer-Tropsch process and sold as a product.
• the secondary water enriched stream is then subjected to biological treatment in step c).
• the biological treatment may include anaerobic treatment or aerobic treatment or a combination of aerobic or anaerobic treatment.
• the anaerobic and/ or aerobic treatment methods may be the same as are conventionally used for domestic and industrial wastewater treatment.
• biological treatment may include anaerobic treatment followed by aerobic treatment.
• the anaerobic and/ or aerobic treatment methods may be the same as are conventionally used for domestic and industrial wastewater treatment.
• the anaerobic and/ or aerobic treatment may include adding nutrients in the form of nitrogen (e.g. urea, ammonia or ammonium salts) and phosphorus (e.g. phosphate salts) containing compounds to accelerate microbiological degradation of the organic constituents.
• nitrogen e.g. urea, ammonia or ammonium salts
• phosphorus e.g. phosphate salts
• pH control using alkali salts such as lime, caustic and soda ash may be required due to the acidity of the water.
• Anaerobic digestion typically yields methane, carbon dioxide and sludge as products along with a water enriched stream.
• the methane may be released to the environment via an acceptable system or, preferably, recovered. Recovered methane may be used as a fuel or energy source or returned for reforming (where natural gas is used as a feedstock for the Fischer- Tropsch synthesis process) or it may be chemically or biologically converted to products.
• the sludge may be incinerated, used as land fill or as a fertiliser or soil conditioner.
• a wide range of technologies may be used in the aerobic treatment of the secondary water enriched stream. Such technologies may be selected from group including: Activated Sludge processes, High-rate Compact Reactors, Biological Aerated Filters, Trickling filters, Rotating Biological Contactors, Membrane Bioreactors, and Fluidised Bed reactors.
• SCP Single Cell Protein
• aerobic treatment typically yields carbon dioxide and sludge as byproducts.
• the carbon dioxide may be released to the environment.
• the sludge may be incinerated, used as land fill, fertilizer, soil conditioner or as a source of SCP.
• Removal of the majority of the organic material from secondary water enriched streams originating from LTFT processes may be undertaken in a single biological treatment step.
• Removal of the majority of the organic material from secondary water enriched streams originating from HTFT processes may require a bulk organic carbon removal step (anaerobic digestion) followed by a second biological polishing step (aerobic oxidation) to remove residual organic material.
• the quartic treatment stage may be aimed at removing suspended solids from the tertiary water-enriched stream produced during biological treatment.
• Suspended solid removal may be achieved by methods selected from the group including: sand filtration, membrane separation (e.g. micro- or ultrafiltration), sedimentation (with or without the use of flocculants), dissolved air flotation (with or without the use of flocculants) and centrifugation.
• sand filtration membrane separation (e.g. micro- or ultrafiltration)
• sedimentation with or without the use of flocculants
• dissolved air flotation with or without the use of flocculants
• Fischer-Tropsch reaction which generates the Fischer-Tropsch reaction water may also produce other Fischer-Tropsch products.
• Fischer-Tropsch products may be processed further, for example by hydroprocessing, to produce products including synthetic crude oil, olefins, solvents, lubricating, industrial or medicinal oil, waxy hydrocarbons, nitrogen and oxygen containing compounds, motor gasoline, diesel fuel, jet fuel and kerosene.
• Lubricating oil includes automotive, jet, turbine and metal working oils.
• Industrial oil includes well drilling fluids, agricultural oils and heat transfer fluids.
• a process for the production of highly purified water from Fischer-Tropsch reaction water which process includes at least the steps of: a) a primary treatment stage comprising an equilibrium staged separation process for removing at least a fraction of non-acid oxygenated hydrocarbons from the Fischer-Tropsch reaction water to produce a primary water enriched stream; b) a secondary treatment stage comprising liquid-liquid extraction for removing at least a fraction of organic acids from at least a portion of the primary water enriched stream to produce a secondary water enriched stream; c) a tertiary treatment stage comprising biological treatment for removing at least a fraction of acidic oxygenated hydrocarbons from at least a portion of the secondary water enriched stream to produce a tertiary treated water enriched stream; and d) a final treatment stage comprising a dissolved salt and organic removal stage for removing at least some dissolved salts and organic constituents from at least a portion of the tertiary water enriched stream.
• the process may furthermore include a quartic treatment stage comprising solid- liquid separation for removing at least some solids from at least a portion of the tertiary water enriched stream to produce a quartic water enriched stream which may then be subjected to final treatment.
• a quartic treatment stage comprising solid- liquid separation for removing at least some solids from at least a portion of the tertiary water enriched stream to produce a quartic water enriched stream which may then be subjected to final treatment.
• highly purified water is to be interpreted as meaning an aqueous stream having a COD of less than 50 mg/1, a pH of between 6,0 and 9,0, a suspended solids content of less than 50 mg/1 and a total dissolved solids content of less than 100 mg/1.
• the non-acid oxygenated hydrocarbons are typically selected from the group including: alcohols, aldehydes, and ketones, are more specifically selected from the group including: acetaldehyde, propionaldehyde, butyraldehyde, acetone, methyl propyl ketone, methanol, ethanol, propanol, butanol, pentanol, hexanol, and heptanol.
• the acidic oxygenated hydrocarbons are typically selected from the group including: formic acid, acetic acid, propionic aid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, and octanoic acid.
• a number of equilibrium staged separation processes are suitable for use in the primary treatment stage. Such processes may include conventional distillation processes typically used in the refining and petrochemical industry as well as solvent extraction using either conventional liquid solvents or liquefied gases.
• Fischer-Tropsch reaction water When distillation is used as the primary treatment stage, the bulk of the non-acid oxygenated hydrocarbons contained in the Fischer-Tropsch reaction water are removed, leaving predominantly mono-carboxylic acids (e.g. acetic acid, propionic acid) and optionally trace quantities of non-acid compounds.
• mono-carboxylic acids e.g. acetic acid, propionic acid
• Fischer-Tropsch reaction water that has undergone primary treatment is known as Fischer-Tropsch acid water.
• the overheads from distillation may be recovered and worked-up to products, or may be used for fuel or as an energy source.
• the primary treatment stage may include degassing of the Fischer-Tropsch reaction water before further processing to remove compounds having a very low boiling point and dissolved gases from the Fischer-Tropsch reaction water.
• Fischer-Tropsch acid water originating from HTFT iron catalyst processes which water has undergone primary treatment has limited application due to the relatively high concentrations (> 1 % by mass) of organic acids remaining in the Fischer-Tropsch acid water and further treatment of the water is required.
• Fischer-Tropsch acid water originating from cobalt-based LTFT processes which water has undergone primary treatment contains significantly lower organic acid concentrations ( ⁇ 0.1% by mass) and can therefore, following neutralization, be released to the environment if sufficient dilution is available and discharge standards permit.
• This primary water enriched stream may also have limited application as process water.
• the liquid-liquid extraction technique used during the secondary treatment stage may be differential contacting or stagewise contacting.
• the differential contacting technique may include using equipment selected from the group including: spray columns, packed columns, rotating disc contactors and Da Laval contactors and equivalents thereof.
• the stagewise contacting technique may include using equipment selected from the group including: mixer settlers, perforated plate columns and controlled cycling columns.
• the solvent used during step b) may be selected from a group of water insoluble solvents having an affinity for acids, said group including ethers, acetates, amides, and phosphene oxides, and more specifically from the group including:.alkyl ethers, ethyl acetate, alkyl phosphene oxides, and alkyl amides.
• Step b) typically yields an organic acid enriched extract stream and a water enriched raffinate stream or secondary water enriched stream.
• a mixed hydrocarbon stream containing C4+ hydrocarbons, solvent and Fischer Tropsch acid water may also be generated. This hydrocarbon stream can be incinerated, send to biological treatment or wgrked-up to recover the heavier acids.
• the extract stream may be refined and/ or worked-up to recover the solvent. Conventional distillation is typically used for solvent recovery. Alternatively, the solvent thus obtained may be recycled to step b) or it may be combined with suitable streams produced during the Fischer-Tropsch process.
• the secondary water enriched stream obtained in step b) is then subjected to biological treatment in step c).
• the biological treatment may include anaerobic treatment or aerobic treatment.
• biological treatment may include anaerobic treatment followed by aerobic treatment.
• the anaerobic and/ or aerobic treatment methods may be the same as are conventionally used for domestic and industrial wastewater treatment.
• the anaerobic and/ or aerobic treatment may include adding nutrients in the form of nitrogen (e.g. urea, ammonia or ammonium salts) and phosphorus (e.g. phosphate salts) containing compounds to accelerate microbiological degradation of the organic constituents.
• nitrogen e.g. urea, ammonia or ammonium salts
• phosphorus e.g. phosphate salts
• pH control using alkali salts such as lime, caustic and soda ash may be required due to the acidity of the water.
• Anaerobic digestion typically yields methane, carbon dioxide and sludge as products along with a tertiary water enriched stream.
• the methane may be released to the environment via an acceptable system or, preferably, recovered. Recovered methane may be used as a fuel or energy source or returned for reforming (where natural gas is used as a feedstock for the Fischer- Tropsch synthesis process) or it may be chemically or biologically converted to products.
• the sludge may be incinerated, used as land fill or as a fertiliser or soil conditioner.
• a wide range of technologies may be used in the aerobic treatment of the raffinate stream produced during from step b). Such technologies may be selected from group including: Activated Sludge processes, High-rate Compact Reactors, Biological Aerated Filters, Trickling filters, Rotating Biological Contacters, Membrane Bioreactors, and Fluidised Bed reactors.
• SCP Single Cell Protein
• aerobic treatment typically yields carbon dioxide and sludge as byproducts.
• the carbon dioxide may be released to the environment.
• the sludge may be incinerated, used as land fill, fertilizer, soil conditioner or as a source of SCP.
• Removal of the majority of the organic material from secondary water enriched streams originating from LTFT processes may be undertaken in a single biological treatment step.
• Removal of the majority of the organic material from secondary water enriched streams originating from HTFT processes may require a bulk organic carbon removal step (anaerobic digestion) followed by a second biological polishing step (aerobic oxidation) to remove residual organic material.
• the quartic treatment stage may be aimed at removing suspended solids from the tertiary water-enriched stream produced during biological treatment. Suspended solid removal may be achieved by methods selected from the group including: sand filtration, membrane separation (e.g. micro- or ultrafiltration), sedimentation (with or without the use of flocculants), dissolved air flotation (with or without the use of flocculants) and centrifugation.
• sand filtration e.g. micro- or ultrafiltration
• sedimentation with or without the use of flocculants
• dissolved air flotation with or without the use of flocculants
• Residual organic species not removed during biological treatment and solids removal may be removed by methods selected from the group including: chemical oxidation using agents such as ozone and hydrogen peroxide, ultraviolet light generated free radicals and adsorption/absorption processes including activated carbon treatment and organic scavenging resins.
• Dissolved salts originating from tertiary treatment (i.e. pH control chemicals, nutrient addition) and/or from the co-treatment of other process effluents, can be further reduced by methods from the group including: ion exchange, reverse osmosis, nano- filtration and chemical precipitation processes including hot and cold lime softening.
• the water will contain only a small amount of dissolved solids because the Fischer-Tropsch reaction water is essentially a dissolved solids- free stream.
• the low levels of residual salts in the purified water are a result of controlled addition of chemicals used during the purification process sequence and/or the co-treatment of other dissolved solids containing effluents.
• the residual salts could include Ca, Mg, Na, K, Cl, S0 ⁇ HC0 3 and C0 3 combinations.
• the low dissolved solids concentrations in Fischer-Tropsch reaction water can simplify and reduce the costs of the purification process.
• Fischer-Tropsch reaction which generates the Fischer-Tropsch reaction water may also produce other Fischer-Tropsch products.
• Fischer-Tropsch products may be processed further, for example by hydroprocessing, to produce products including synthetic crude oil, olefins, solvents, lubricating, industrial or medicinal oil, waxy hydrocarbons, nitrogen and oxygen containing compounds, motor gasoline, diesel fuel, jet fuel and kerosene.
• Lubricating oil includes automotive, jet, turbine and metal working oils.
• Industrial oil includes well drilling fluids, agricultural oils and heat transfer fluids.
• Figure 1 shows a simplified block diagram of a method according to the present invention including various treatment options.
• the Fischer-Tropsch reaction water 12 is fed to a distillation column 14 for primary treatment.
• stream 16 contains predominantly organic constituents whilst stream 18 is a primary water enriched stream. At least a fraction of the organic acids in stream 18 are thereafter removed by liquid- liquid separation 20.
• Liquid-liquid separation 20 yields yields an organic acid enriched extract stream 22, a secondary water enriched or raffinate stream 24 and a mixed hydrocarbon stream.
• the secondary water enriched stream is subjected to biological treatment 28 which yields gases 30, sludge 32 and a tertiary water enriched stream 34.
• biological treatment can take the form of anaerobic treatment or aerobic treatment or a combination of the two.
• the tertiary water enriched stream 34 from biological treatment 28 is typically subjected to a softening step 36 which yields a softened tertiary water enriched stream 38 and sludge 40.
• the softened tertiary water enriched stream 38 is subjected to solid-liquid separation 42 which process yields a purified water stream 44 and a sludge stream 46.
• An additional step, typically membrane separation 47, for removing at least a fraction of dissolved salt and organic constituents contained in the purified water stream 44 can be performed after solid-liquid separation 42 to produce a stream of highly purified water 48 and sludge stream 50.
• the minimum water quality requirements are as set out in Table 2 below and the operating conditions of the equipment used in the method as well as suitable treatment options can be selected accordingly.
• Table 3 Typical Composition of HTFT Reaction Water Feed and Acid Water Bottoms (water enriched stream) after Primary Treatment (Distillation)
• the primary water enriched stream was cooled to 50 °C and fed into a counter current packed extractor column in which the primary water enriched stream came into contact with an Alkyl Ether, namely MTBE, as organic solvent.
• Alkyl Ether namely MTBE
• the extract exited the top of the extractor column with the extracted acids and some water, while the secondary water enriched stream exited the extractor bottom with a significantly lower acid content than the primary water enriched stream that entered the extractor column and some dissolved solvent.
• the extractor column was operated at 440 kPa and 53 °C with an acetic acid recovery rate of 55%.
• the recovery of the higher acids ranged from 97% to more than 99.9%.
• the solvent was recovered from the extract in two distillation steps, which were .configured similarly to a double effect evaporator.
• the first distillation (at 274 kPa and 96 °C) operated as an evaporator with some vapour washing.
• the mixed acid stream exiting the second distillation column was fed to a purification section.
• the lean solvent was recycled to the extractor column and the secondary water enriched stream was recycled to a raffinate stripper.
• the solvent contained in the secondary water enriched stream as well as the solvent from the extractor and solvent recovery section was recovered in a packed stripper column operated at a pressure of at 42 kPa and a temperature of 106 °C and recycled.
• the water bottom product from the stripper (secondary water enriched stream) was fed to a biological treatment section.
• This mixed hydrocarbon stream was sent to effluent disposal.
• the top stream from the distillation column containing acetic acid, propionic acid and lighter hydrocarbons was fed to the next distillation column operated at 62 kPa and 154 °C.
• the propionic acid product of minimum mass 99.5% purity was recovered as a vapour side-draw from the bottom of the column and then condensed.
• the liquid overhead stream from the column was fed to a distillation column operated at a pressure of 42 kPa and a temperature of 130 °C where the acetic acid was dried.
• the overhead stream containing light impurities, water and some acetic acid can, for example, be used as fuel for thermal oxidation.
• the acetic acid bottom stream from the distillation column was further purified by removing impurities capable of being oxidized by treating the stream with KMnO .
• the treated stream was returned to the same column.
• Acetic acid product having a minimum of 99.85% (by mass) purity was recovered as a vapour side draw and condensed.
• the first stage of the biological section comprised an open equalization tank with a HRT of 8 - 12 h.
• the secondary water enriched stream obtained from the extraction step was fed to a Down-flow Packed Bed (DPB) anaerobic digester containing plastic packing material.
• DPB Down-flow Packed Bed
• CaOH Caustic soda
• the DPB anaerobic digester was operated under the following conditions:
• the COD and SS concentrations of the effluent after anaerobic digestion were ca. 600 mg 0 2 /l and ca. 500 mg SS/I, respectively.
• the COD removal across the reactor was on average 90 %.
• tertiary water enriched stream obtained from anaerobic treatment was further subjected to aerobic treatment in an activated sludge basin.
• Feed to recycle ratio 1 : 2.5
• a sludge yield of 0.15 kg sludge/kg COD was achieved and the sludge produced was incinerated.
• the tertiary water enriched stream obtained from aerobic treatment contained COD and SS concentrations of 100 mg 0 2 /l and 70 mg SS/I, respectively.
• Sand filtration was used to reduce the SS concentration of the tertiary water enriched stream obtained from aerobic treatment to 30 mg/l. During sand filtration, the COD concentration of the tertiary water enriched stream obtained from aerobic treatment was further reduced to ca. 55 mg/1. This water has application as process cooling water.
• the pH of the purified water from the microfiltration unit was then adjusted to pH 8.5 using sodium hydroxide, and the purified water was pumped to a reverse osmosis unit fitted with a high rejection sea water polyamide membrane.
• a permeate flux rate was then adjusted to pH 8.5 using sodium hydroxide, and the purified water was pumped to a reverse osmosis unit fitted with a high rejection sea water polyamide membrane.
• the reverse osmosis unit yielded a highly purified water stream containing COD and TDS concentrations of ⁇ 40 mg 0 2 /l and ⁇ 20 mg TDS/I.

Landscapes

• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Chemical & Material Sciences (AREA)
• Hydrology & Water Resources (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Extraction Or Liquid Replacement (AREA)
• Biological Treatment Of Waste Water (AREA)
• Activated Sludge Processes (AREA)
• Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
• Physical Water Treatments (AREA)
• Treatment Of Water By Oxidation Or Reduction (AREA)

Priority Applications (5)

Applications Claiming Priority (4)

Related Child Applications (1)

Publications (1)

Family

ID=27669345

Family Applications (1)

Country Status (10)

Cited By (9)

Families Citing this family (33)

Citations (6)

Family Cites Families (11)

• 2003
  • 2003-06-18 BR BRPI0311936-0A patent/BR0311936B1/pt not_active IP Right Cessation
  • 2003-06-18 GB GB0314076A patent/GB2391226B/en not_active Expired - Fee Related
  • 2003-06-18 CN CNB038141272A patent/CN100445222C/zh not_active Expired - Fee Related
  • 2003-06-18 JP JP2004513190A patent/JP4323423B2/ja not_active Expired - Fee Related
  • 2003-06-18 AU AU2003276158A patent/AU2003276158B2/en not_active Ceased
  • 2003-06-18 RU RU2004138560/15A patent/RU2331592C2/ru active
  • 2003-06-18 NL NL1023693A patent/NL1023693C2/nl not_active IP Right Cessation
  • 2003-06-18 WO PCT/ZA2003/000078 patent/WO2003106353A1/en not_active Ceased
• 2004
  • 2004-12-16 US US11/014,517 patent/US7150831B2/en not_active Expired - Lifetime
• 2005
  • 2005-01-17 NO NO20050266A patent/NO20050266L/no not_active Application Discontinuation

Patent Citations (6)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events