Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
  • B01D24/36—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof with the filter bed fluidised during the filtration
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D21/00—Separation of suspended solid particles from liquids by sedimentation
  • B01D21/0039—Settling tanks provided with contact surfaces, e.g. baffles, particles
  • B01D21/0042—Baffles or guide plates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D21/00—Separation of suspended solid particles from liquids by sedimentation
  • B01D21/0039—Settling tanks provided with contact surfaces, e.g. baffles, particles
  • B01D21/0045—Plurality of essentially parallel plates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D21/00—Separation of suspended solid particles from liquids by sedimentation
  • B01D21/10—Settling tanks with multiple outlets for the separated liquids
  • B01D21/16—Settling tanks with multiple outlets for the separated liquids provided with flocculating compartments
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D21/00—Separation of suspended solid particles from liquids by sedimentation
  • B01D21/24—Feed or discharge mechanisms for settling tanks
  • B01D21/2433—Discharge mechanisms for floating particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D21/00—Separation of suspended solid particles from liquids by sedimentation
  • B01D21/24—Feed or discharge mechanisms for settling tanks
  • B01D21/2444—Discharge mechanisms for the classified liquid
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D21/00—Separation of suspended solid particles from liquids by sedimentation
  • B01D21/24—Feed or discharge mechanisms for settling tanks
  • B01D21/2488—Feed or discharge mechanisms for settling tanks bringing about a partial recirculation of the liquid, e.g. for introducing chemical aids
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
  • B03D1/00—Flotation
  • B03D1/001—Flotation agents
  • B03D1/002—Inorganic compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
  • B03D1/00—Flotation
  • B03D1/001—Flotation agents
  • B03D1/004—Organic compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
  • B03D1/00—Flotation
  • B03D1/14—Flotation machines
  • B03D1/1412—Flotation machines with baffles, e.g. at the wall for redirecting settling solids
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
  • B03D1/00—Flotation
  • B03D1/14—Flotation machines
  • B03D1/1431—Dissolved air flotation machines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
  • B03D1/00—Flotation
  • B03D1/14—Flotation machines
  • B03D1/1481—Flotation machines with a plurality of parallel plates
• • 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
  • C02F1/24—Treatment of water, waste water, or sewage by flotation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
  • B03D2201/00—Specified effects produced by the flotation agents
  • B03D2201/002—Coagulants and Flocculants
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
  • C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
  • C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
  • C02F1/56—Macromolecular compounds

Definitions

• the present invention relates to treatment systems for clarification of a fluid stream and, more particularly, to buoyant media introduced into the flow to induce a rising force on particles to be removed from the fluid.
• Background of the Invention Technologies for the separation of components of a fluid stream on the basis of density are well known in the art. The simplest systems rely on differences in densities alone ' to accomplish this separation, with heavier components settling, in the absence of agitation, to the bottom of the fluid for removal .
• a coagulant is a substance that produces a loosely-massed precipitate. As the precipitate forms, it entraps solid particles contained in the fluid.
• Aluminum sulfate and ferric sulfate are among the materials used in the art as coagulants.
• Flocculant aids are thus effective as solid-liquid separating agents. Flocculant aids are typically synthetic water soluble polymers based on acrylamide. There are some natural occurring polymers, such as chitosan, that can be used for this purpose. Entrain ent can be used in conjunction with flocculation to expedite the separation process.
• grains of sand can be introduced to the fluid to be treated.
• the floe that forms entraps the grains of sand, and the density of the floe is increased as is its settling speed.
• bubbles may be generated as the floe is formed, and their entrainment produces a floe that rises to the surface of the fluid rather than settling to the bottom.
• additional equipment and operating expenses are required to generate the bubbles.
• Other settling media may be selected on the basis of specific gravity, particle size, surface properties, or chemical properties. Increasing the concentration of these settling media improves the efficiency of the flocculation process, because more particle collisions result and the size of the resulting agglomerated particles increases more rapidly. Also, the settling capacity of the system increases with concentration. However, increasing the concentration of entrained materials increases the cost of the separation process, and increases the volume of the waste materials produced. For settling media with specialized properties, these cost constraints can be significant.
• Solids separation processes employing settling inherently require energy in the flocculation stage, produce large volumes of sludge, produce effluent with small, difficult to settle particles, and require large, complex process vessels. These characteristics lead to increased costs. Accordingly, a need exists to reduce the costs associated with solids separation in high rate fluid clarification systems.
• the present invention is a clarification system for fluids, in which particles are separated from the fluid by flotation and in which a buoyant media inducing the flotation is recycled.
• Buoyant media separation processes according to the invention offer a number of advantages over settling media processes according to the invention. Less energy is required in the flocculation stage in a buoyant media separation process. The volume of sludge produced is lower, and the sludge solids concentration is higher; no further sludge concentration is required. Also, process vessel depth is substantially less for buoyant media separation processes, and process vessel construction is simpler and more economical .
• Fluid to be treated passes into a mixing chamber in which it is mixed rapidly with coagulants and flocculants.
• the resulting mixture then passes into a flocculation chamber in which the buoyant media are added and mixed and in which the flocculation process produces agglomerated particles.
• the product of the flocculation chamber passes into a flotation chamber.
• the flotation chamber is configured so that the removal of clarified fluid draws the fluid entering the chamber upward, hastening the generation of a sludge layer containing separated particles and buoyant media at the top of the chamber.
• the flotation chamber can be equipped with a flotation assistance device, such as dissolved air flotation, diffused air, or froth flotation system, to further hasten the flow of separated particles and buoyant media upward.
• a flotation assistance device such as dissolved air flotation, diffused air, or froth flotation system
• lamella plates, tubes or other coalescing surfaces can be added to the flotation chamber to improve the separation of the buoyant floes .
• Submerged membrane systems can be provided in the separation tank to remove the need for downstream filtration systems.
• the clarified fluid obtained from the separation of sludge is removed from the bottom of the flotation chamber, and is optionally filtered.
• the sludge layer is removed from the top of the flotation chamber by any of a number of methods of removal well known in the art, such as a mechanical skimmer or by hydraulic desludging.
• the sludge layer then passes into a buoyant media recovery unit, wherein the buoyant media are separated from the sludge stream.
• the sludge stream is disposed of and the buoyant media are recycled into the flocculation chamber.
• the buoyant media recovery unit can make use of various types of devices to effect the separation, such as a centrifugal separator, centrifugal screener, cross-flow sieve, or vibratory screen separator.
• the floes can be subjected to shearing forces to separate the media from the waste particles, and the two phases are then allowed to separate.
• Fig. 1 is a schematic diagram of components and the pattern of flow of the clarifier device of the present invention.
• Fig. 2 is a schematic diagram of a flotation chamber of the present invention, including lamella plates.
• Fig. 3 is a schematic diagram of a flotation chamber of the present invention, including tubes.
• Fig. 4 is a schematic diagram of a flotation chamber of the present invention, including an immersed membrane module.
• the high rate clarification system of this invention makes use of high concentrations of particles of a buoyant media.
• the high concentrations improve the efficiency of flocculation and enable the system to produce a high rate of flotation.
• fluid to be treated flows into a mixing chamber 10.
• a coagulant is added to the fluid in this chamber 10.
• the coagulants are typically metal salts, such as aluminum sulfate, ferric sulfate, or PAC1, or can be any of the coagulant-type polymers currently offered by chemical suppliers.
• the amount of coagulant needed depends on factors, such as the concentration of solids to be removed from the fluid, but is typically in the range of 5 and 180 milligrams per liter of fluid.
• the resulting mixture passes through a flocculation chamber feed line 14 into a flocculation chamber 20. In the flocculation process, aggregate suspended particles grow in size as they combine.
• Buoyant media and a flocculant aid are added to the fluid mixture in chamber 20.
• a flocculant is added to chamber 20 with the buoyant media.
• Typical flocculants for this application are synthetic water soluble polymers based on acrylamide. There are also some naturally occurring polymers that can be used such as chitosan. The amount of flocculant needed depends on factors, such as the concentration of solids to be removed from the fluid, but is typically in the range of 0.1 to 1.0 milligrams per liter of fluid. In the flocculation process, aggregate suspended particles grow in size as they combine.
• the buoyant media may be finely divided solids, but may also be solids that have been foamed or otherwise provided with internal voids.
• the buoyant media may include a plastic powder which has a specific gravity less than 1.0.
• the plastic can be, for example, polypropylene or polyethylene, but there are various other lightweight materials that can be used.
• Particle size for the buoyant media may be in the range of 10 to 500 microns, preferably in the range of 30 to 250 microns.
• the media will typically be added at a rate of 0.1 to 5 grams per liter of fluid mixture.
• the fluid mixture containing coagulants, flocculants, buoyant media, and the solids to be separated, then passes through a flotation chamber feed line 24, into a flotation chamber 30.
• Flotation chamber 30 is configured so that entering fluid is directed upward, expediting the flotation process.
• a baffle 32 is an example of a structure directing entering fluid upward.
• the sludge layer 34 is separated from the flotation chamber 30 into a sludge hopper 36. The separation can be effected by a chain-and- flight or reciprocating skimmer or other sludge removal device.
• a clarified fluid 38 is formed by the removal of coagulant and flocculant from the entering fluid by the buoyant media.
• a flotation assistance device 40 can be used to further hasten the flow of separated particles and buoyant media upward.
• Flotation assistance device 40 may be a dissolved air flotation (DAF) system or DAF pump, or dispersed air system or blower. The output from flotation assistance device 40 enters flotation chamber 30 through a flotation assistance line 42.
• DAF dissolved air flotation
• Clarified fluid 38 is withdrawn from flotation chamber 30 through a clarified fluid withdrawal line 44 or other process outlet.
• Lamella plates 45, tubes 45' or an immersed membrane module 45" can be added to the flotation cell to hasten the separation process as shown in Fig. 2, Fig. 3 and Fig. 4.
• a portion of the clarified fluid 38 can be recycled through a clarified fluid recycling line 46 to flotation assistance device 40.
• the sludge layer 34 is removed from sludge tank
• Buoyant media recovery unit 50 may make use of a screening device to recover the buoyant flotation media, such as a vibratory separator, centrifugal screener, or a cross-flow sieve.
• the screens used are sized to selectively remove the buoyant flotation particles.
• Other separation devices such as centrifuges, hydrocyclones, or fluidized bed classifiers, may also be used.
• the separated sludge is removed from buoyant media recovery unit 50 through a separated sludge line 52.
• the separated buoyant flotation particles are removed from buoyant media recovery unit 50 through a buoyant flotation particle recycling line 54 and recycled into flocculation chamber 20.
• the modular tanks 10, 20 and 30 in Fig. 1 with pipe connections 14, 24 may be replaced by a single large tank (not shown) having appropriate over-weir and under-weir devices to define separate chambers which are fluidly connected in the same general manner as shown in Fig. 1.

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

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• 2001
  • 2001-02-09 WO PCT/US2001/004139 patent/WO2001060494A1/en not_active Application Discontinuation
  • 2001-02-09 AU AU2001234963A patent/AU2001234963A1/en not_active Abandoned
  • 2001-02-09 EP EP01907149A patent/EP1268027A1/de not_active Withdrawn

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