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
  • C02F3/02—Aerobic processes
  • C02F3/12—Activated sludge processes
  • C02F3/1278—Provisions for mixing or aeration of the mixed liquor
  • C02F3/1284—Mixing devices
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
  • B01F23/20—Mixing gases with liquids
  • B01F23/23—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
  • B01F23/233—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements
  • B01F23/2331—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
  • B01F23/20—Mixing gases with liquids
  • B01F23/23—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
  • B01F23/233—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements
  • B01F23/2331—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements
  • B01F23/23311—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements through a hollow stirrer axis
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
  • B01F23/20—Mixing gases with liquids
  • B01F23/23—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
  • B01F23/233—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements
  • B01F23/2331—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements
  • B01F23/23314—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements through a hollow stirrer element
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
  • B01F23/20—Mixing gases with liquids
  • B01F23/23—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
  • B01F23/235—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids for making foam
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
  • B01F27/27—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices
  • B01F27/271—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices with means for moving the materials to be mixed radially between the surfaces of the rotor and the stator
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
  • B01F27/27—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices
  • B01F27/271—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices with means for moving the materials to be mixed radially between the surfaces of the rotor and the stator
  • B01F27/2714—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices with means for moving the materials to be mixed radially between the surfaces of the rotor and the stator the relative position of the stator and the rotor, gap in between or gap with the walls being adjustable
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
  • B01F27/80—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis
  • B01F27/81—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis the stirrers having central axial inflow and substantially radial outflow
  • B01F27/812—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis the stirrers having central axial inflow and substantially radial outflow the stirrers co-operating with surrounding stators, or with intermeshing stators, e.g. comprising slits, orifices or screens
• • 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
  • C02F3/02—Aerobic processes
  • C02F3/12—Activated sludge processes
  • C02F3/20—Activated sludge processes using diffusers
• • C—CHEMISTRY; METALLURGY
  • C05—FERTILISERS; MANUFACTURE THEREOF
  • C05F—ORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C, e.g. FERTILISERS FROM WASTE OR REFUSE
  • C05F3/00—Fertilisers from human or animal excrements, e.g. manure
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M27/00—Means for mixing, agitating or circulating fluids in the vessel
  • C12M27/02—Stirrer or mobile mixing elements
  • C12M27/04—Stirrer or mobile mixing elements with introduction of gas through the stirrer or mixing element
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
  • B01F27/05—Stirrers
  • B01F27/11—Stirrers characterised by the configuration of the stirrers
  • B01F27/115—Stirrers characterised by the configuration of the stirrers comprising discs or disc-like elements essentially perpendicular to the stirrer shaft axis
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
  • B01F27/27—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices
  • B01F27/271—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices with means for moving the materials to be mixed radially between the surfaces of the rotor and the stator
  • B01F27/2712—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices with means for moving the materials to be mixed radially between the surfaces of the rotor and the stator provided with ribs, ridges or grooves on one surface
• • 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
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A40/00—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
  • Y02A40/10—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in agriculture
  • Y02A40/20—Fertilizers of biological origin, e.g. guano or fertilizers made from animal corpses
• • 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
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/141—Feedstock
  • Y02P20/145—Feedstock the feedstock being materials of biological origin
• • 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
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W10/00—Technologies for wastewater treatment
  • Y02W10/10—Biological treatment of water, waste water, or sewage

Definitions

• the present invention relates to a method for fermenta ⁇ tion of especially highly viscous substrate in a fermen ⁇ tation tank with a controlled mixing of air and an arrangement for mixing air into the substrate.
• One known arrangement for supply of air consists of a tube coil provided with holes which is arranged close to the bottom of the fermentation tank. The curtain of air bubbles which is formed is then distributed in the tank by means of a mixer of turbine type.
• the proposed method is mainly characterized in that the addition of air to the substrate takes places in two steps.
• a small part of the substrate is mixed with a larger part of air in such a way that a foam comprising air bubbles is formed.
• the formed foam is distributed and mixed into the substrate in a mixing zone close to the bottom in the fermentation tank, at which very small air bubbles are obtained, the rising speed of which is so low that the degree of utilization of oxygen in percent of the added amount of oxygen is above 20 %.
• the foam When the foam is formed energy is added to the liquid which corresponds to the surface tension in the newly formed surfaces of liquid on both sides of the foam lamella. According to the invention the foam is formed in one moment and in the second the gas volumes which are present in the foam are distributed in the sur ⁇ rounding substrate. The addition of air may therefore take place with a low energy consumption.
• the mixing of foam may take place by forcing formed foam into the substrate by way of tube coils close to the bottom of the tank.
• the air bubbles in the formed foam may also be distri ⁇ ubbed in the substrate by hydromechanical working.
• a hydromechanical working may take place with means, which by way of a shearing action divide the foam in connection with the mixing.
• the air bubbles in the foam may alternatively be divided further prior to the mixing in the fermentation tank.
• a smaller diameter of the foam bubbles demands an increase in the amount of liquid present in the surrounding liquid lamella.
• a mechanical reduction of the size of the foam bubbles must therefore be combined with an addition of liquid. This takes place most simply by a repeated remixing of already formed foam and liquid.
• the diameter of the air bubbles is in the interval between some tenth part of a milli ⁇ meter up to some millimeters.
• the diameter of the air bubbles is suitably below one millimeter.
• Such small air bubbles have a low rising speed which means that they are available for a longer time for the microorganisms in the fermentation tank. The more viscous the substrate is the slower is the rising speed.
• Many small air bubbles also give smaller average distance between the air bubbles.
• the contact area between gas-liquid is large, which also results in a high and constant degree of utilization of oxygen.
• Foam forming means may if so is desired also be added to the substrate in the fermentation tank.
• a device for mixing of air into highly viscous substrate comprises a tube for addition of air to a rotating, foam forming means which is arranged submerged in the substrate in the fermentation tank.
• the means comprises two elements where at least one of the elements has a side with a surface structure with lowered and/or raised parts.
• the spaces which are formed in the lowered parts in the structure are connected to the air pipe and surrounding substrate such that a foam is formed between the elements.
• Means to distribute the formed foam in the substrate are arranged close to the bottom of the tank.
• a suit ⁇ able design of the surface structure of at least one of the elements may be achieved in many different ways.
• the structure may be formed with regular or irregular bars, grooves, rods or tube pieces.
• the vital thing is that the element has an upper surface which in corporation with the corresponding surface of the other element may form a thin liquid film when the elements move in relation to each other.
• the surface structure of the element shall also contain lowered parts intended to contain air in order to facilitate foam forming.
• the elements are movable in a transversal way in rela ⁇ tion to each other, which means that one of the elements may be movable and the other stationary or both may be movable.
• the simpliest arrangement from a constructive point is that one of the elements is stationary.
• the liquid is sheared into a thin film. Since the structure has a form with lowered or raised parts, the liquid layer is exposed to a lowered part, that is a space which is mainly filled with air and earlier formed foam. For each passage a number of foam bubbles consequently is formed.
• the simpliest way to create the necessary movement to form foam is based on rotation.
• the foam forming means is suitably designed such that it also distributes the formed foam in the substrate. If it is desirable the foam formation may take place on some other place in the fermentation tank.
• the formation of foam advantageously takes place between a rotating part and a stationary part. If the rotating part is shaped as a cylindrical part within a stationary house, the movable or the stationary part or both are provided with grooves or rods with a pitch having a screw form.
• the foam forming means is with advantage shaped such that the two elements consist of one stationary and one rotating disc, which both have a structure with lowered and/or raised parts in the shape of radial rods, at which the space between the discs is connected to the tube for air addition and holes for addition of substrate are arranged in the stationary and/or in the rotating disc.
• the formed foam is pumped into the surrounding liquid by influence of the rotation.
• the foam forming means may have a little diameter, which at a certain speed of the motor gives a high shearing speed. At the same time there is obtained an efficient distribution of foam in the liquid.
• the distance between lowered and/or raised parts in the surface structure may be 1-100 mm, preferably 10-30 mm.
• the degree of utilization of oxygen in the added air is above 20 %. How well the oxygen may be utilized depends on many factors, for example the shape of the tank, the viscosity of the substrate, the amount of microorganisms and their demands for oxygen. In many processes it is desirable to be able to use the oxygen in an optimal way.
• fermentating liquid manure one wants to obtain such a high degree of oxygen utilization as 90-95 % in order to avoid emission of ammonia.
• fermentating for production of energy one wants to avoid unnecessarily large amounts of air since the heating and moisturizing of the air which passes the substrate constitute a loss of energy.
• the method according to the invention is suitable for example for a fermentation where the substrate consists of liquid manure with a high content of dispersed material.
• the fermentation may be carried through with controlled aerobic conditions, which results in an retardation of the formation of ammonia such that the emission of ammonia to the surrounding atmosphere may be kept low.
• Manure which is obtained when holding animals must be treated in order not to be considered as a waste problem.
• Manure in solid form has since long been composted. Due to the rise of temperature to 40-60° C which takes place during the composting the amount of pathogenic bacterias, parasites and weeds is diminished. The smell is also made more agreable.
• Liquid manure may also be composted, but the composting demands addition of air to the liquid.
• the emission of ammonia to the environment may be reduced considerably.
• Urea is decomposed by the enzyme ureas to ammonia and carbonate ions.
• the de ⁇ composing takes place by strictly aerobic microorganisms which demand a good access of oxygen. If the oxygen concentration is limited the decomposing is hindered.
• the arrangement comprises a tube 1 for addition of air to a foam forming means 2 which is submerged in the sub ⁇ strate in a fermentation tank (not shown).
• An upper stationary disc 3 is connected to the tube 2 for addition of air.
• Under the stationary disc 3 there is a rotating disc 4.
• Both the stationary and the rotating disc have radial grooves or rods 5 (fig 2) .
• both the stationary and the movable disc have holes for addition of substrate. If the substrate contains large amounts of suspended material for example plant fibres, the means is designed with holes only in the rotating disc. The holes are suitably formed such that they are self cleaning.
• the rotating disc may be provided with a sieve arrange ⁇ ment 8 which also rotates.
• the proportions between air and liquid in the foam is controlled by the air flow through the pipe and the liquid flow through the holes together with the characteristica of the pump wheel of the discs 2 and 3 (peripheral speed and the design of the flow channels).
• the pore size of the foam and consequently the size of the air bubbles in the fermentation tank is controlled by the slit height between the stationary and the rota ⁇ ting disc and of the shearing speed of the liquid between the discs.
• the example given below describes how the method accor ⁇ ding to the invention is carried through when composting liquid manure.
• the fermentation tank has a volume of 10 m 3 with a cylindrical form and with a bottom in the form of a frustum of a cone. The diameter was 2,2 m. From the start the tank was unisolated but during the series of trials it was shown that an isolation was demanded. The first trials were carried through with air mixers of the marks Aldo 1004kW and Biojet 2,2 kW. The latter gives a better result than the first but the result was still unsatisfactory.
• the viscosity may be as high as 2000 cP.
• a value of the viscosity ⁇ 300 cP may be used.
• An air bubble of a diameter of 1 mm then has a rising speed of 1,82 mm/sek (Navier-Stok).
• the mean holding time is around 18 min, if the movement of the bubble only depends on differences in density.
• Such a long contact time makes the utilization degree of oxygen high.
• the volume air which is mixed into the substrate may therefore be relatively small. Only 15-20 % of the air flow which earlier used air mixers added, is sufficient to give a satisfactory content of air in the liquid. Even if the power requirement per m 3 mixed air increases when the size of the bubbles is smaller, 'the net power may be low due to the reduction of the air flow.
• the necessary amounts of nitrogen, potassium and phosphor are then added in the form of liquid manure, latrine or industrial waste.
• the amount of carbohydrate which is needed for energy production is added in the form of fibrous waste or plant material.
• a substrate with a high content of energy per volume unit has inferior liquid properties. It is difficult to carry through an addition of oxygen such that the degree of utilization of oxygen is high and the losses of heat to air flowing through the liquid are kept low.
• the method according to the invention may with advantage also be used when the fermentation results in products with a high viscosity.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Life Sciences & Earth Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Microbiology (AREA)
• Hydrology & Water Resources (AREA)
• Wood Science & Technology (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Health & Medical Sciences (AREA)
• Bioinformatics & Cheminformatics (AREA)
• Biodiversity & Conservation Biology (AREA)
• Zoology (AREA)
• Biomedical Technology (AREA)
• Sustainable Development (AREA)
• Biotechnology (AREA)
• Biochemistry (AREA)
• General Engineering & Computer Science (AREA)
• General Health & Medical Sciences (AREA)
• Genetics & Genomics (AREA)
• Apparatus Associated With Microorganisms And Enzymes (AREA)
• Fertilizers (AREA)
• Treatment Of Sludge (AREA)
• Micro-Organisms Or Cultivation Processes Thereof (AREA)
• Distillation Of Fermentation Liquor, Processing Of Alcohols, Vinegar And Beer (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20383195

Family Applications (1)

Country Status (8)

Cited By (1)

Citations (2)

• 1991
  • 1991-06-28 SE SE9102019A patent/SE469073B/sv not_active IP Right Cessation
• 1992
  • 1992-06-26 WO PCT/SE1992/000478 patent/WO1993000302A1/en active IP Right Grant
  • 1992-06-26 EP EP19920914334 patent/EP0642471B1/en not_active Expired - Lifetime
  • 1992-06-26 DK DK92914334T patent/DK0642471T3/da active
  • 1992-06-26 DE DE69228428T patent/DE69228428T2/de not_active Expired - Lifetime
  • 1992-06-26 PL PL92301948A patent/PL170206B1/pl unknown
• 1993
  • 1993-12-27 NO NO934827A patent/NO304825B1/no not_active IP Right Cessation
  • 1993-12-27 FI FI935876A patent/FI108349B/sv not_active IP Right Cessation

Patent Citations (2)

Non-Patent Citations (1)

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