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
  • C02F3/1236—Particular type of activated sludge installations
  • C02F3/1257—Oxidation ditches
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/39—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with hollow discs side by side on, or around, one or more tubes, e.g. of the leaf type
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/88—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices
  • B01D29/885—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices with internal recirculation through the filtering element
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/88—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices
  • B01D29/94—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices for discharging the filter cake, e.g. chutes
  • B01D29/945—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices for discharging the filter cake, e.g. chutes for continuously discharging concentrated liquid
• • 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

• a purification system with filter for seperation of activated sludge and treated water in a procestank A purification system with filter for seperation of activated sludge and treated water in a procestank.
• the invention concerns a purification system of the type defined in the introductory portion of claim 1.It is well-known to perform biological purification using so-called activated sludge.
• Activated sludge is an expression covering colonies of microorganisms which remove organics and nutrients from the liquid which is purified. In an activated sludge treatment plant the mixture of water and activated sludge will be kept in motion and leaves the procestank after a certain time.
• the pupose of the invention is thus to create an activated sludge treatment plant whithout a sedimentation tank.
• the clean water between the activated sludgeflocs is forced through the filter by an all over hydrostatic pfeassure.
• This hydrostatic preassure can be established by installation of an overflowwire for the filtrated water. The wire then controls the hydraulics of the system (fig. 1).
• a horisontal velocity is forced upon the activated sludge, in which the filter is submerged,whereby the filter is cleaned (fig 1). This velocity can be created by different machinery but most often by propellermixers,- rotors or turbines.To ensure the mixing of the suspended matter (microorganisms) the proces most often operates at velocities of 0,2 -0,5 m/sec- By these velocities most of the filtercake will be poured off.
• the velocity of flow along the filter is increased by the displacement of water by the filter and by the reduction of the crosssection area of the flow (fig 3).By submerging a filterunit the velocity of flow along the filter will increase because of the displaced water. The velocity of flow can be further increased by placing several filterunits in a channel with steep walls whereby the crossection area of the flow is reduced (fig 3).
• the filters are provided with smooth sufaces,while a smooth surface prevents the growth of microorganisms on the surface. Further the filters are placed a certain distance under the surface water level to reduce the intensity of light,whereby the growth of algae are inhibited.
• the filters are provided with an artificial cleaning mechanism, consisting of returnwashing of the filter by a liquid or a gas or both, possibly in- termittend.Such a system can be worked out as seen in fig 1.
• the filtrated water runs to a returnwashing basin which is provided with an overflow weir, from where the water runs to the recipient or to further treatment.
• the overflow weir controls the surface water level in the procestank.
• the returnwashing pump In the returnwashing basin the returnwashing pump is pumping treated water backwards through the filters when the filters need cleaning.This return- washing can be supplemented by blowing air backwards through the filters by a blower.Washing water and washing air can be supplied at the same time or intermittend.
• the system is equipped by the necessary valves and controlers.
• the filter can be designed with a hydraulic suction at a part of the surface, or at the whole suface, of the filter( fig. 2).By designig the filter with a hydraulic suck - that means a negative hydrostatic preassure - this suck will remove the microorganisms from the filter and thereby prevent clogging of the filter.
• the pores in the filtermedia can be carried out in such a way that the pores will open further by returnwashing.Hereby suspended matter which is catched in the pores can be released and washed out.This can possibly be done by performing an elastic filtermedia.
• the procestank can be equipped with one or more filterunits.At bigger plants more units will be necessary.
• the filterunits can be installed in different ways.A favourable installation of the filterunits is shown in fig 3. In fig 3 the filterunits are installed side by side between 2 vertical walls in the procestank.Hereby the velocity of flow is increased because of the reduction of the crosssection area of the flow. It is an advantage too that the filterunits easily can bee connected by pipes for filtrated water and for returnwashing by water and air.At even bigger plants several rows of filterunits can be installed behind each other between 2 vertical walls in a procestank ( fig 4 ).
• the filters can have arbitrary geometry.On fig 5 the favourable geometries of the filter is shown.Which geometry at a given purpose is most optimal depends on a combination of the selfcleaning of the filter and the production- and installation costs.A favourable combination of selfcleaning and costs is shown on fig 6.
• the filters can be constructed in different ways. Important is the filter- membrane.
• the filter can be constructed either as a shell or as a uniform unit (fig 7 ).If the filter is constructed as a shell this can be done by different numbers of materials.A favorable design is to construct a stiff framework of steel with perforated plates covered with a filtermembrane.
• a uniform filter can probably consist of foamed plastics with small pores. Returnwashing can bee operated with some filters beeing washed while the other filters are still filtrating.Hereby more constant hydralic flows are maintained.
• Fig. 1 is a top view and sectional view of a treatment plant according to the invention with a filterunit installed in the procestank.
• Fig. 2 is a sectional view of the flow along 2 different geometries of a filter.
• Fig. 3 is a top view of the flow along a filterunit consisting of several filters.
• fig. 4 shows the installation of several filters arranged in 2 rows.
• fig. 5 shows top views of 6 examples of filtergeometry.
• fig. 6 shows top view and sectional views of a favourable filter-construction.
• fig.7 shows a plan section of a filter constructed as a shell and as a uniform body.
• Fig. 1 is a top view and a sectional view of a treatment plant consisting of a procestank (1) with a filterunit (2) and a returnwashing basin (3)- .
• the raw sewage is fed to the procestank at (4) and the cleaned water runs out of the returnwashing basin at (5).
• the activated sludge is aerated by the aggregate (6) and is moved forward by the mixers (7).
• the activated sludge flows along several filters (8),whereby the purified water is filtrated through the filters by a hydraulic gradient from the water surface level (9) in the procestank till the overflowweir (10) in the returnwashing basin.
• returnwashing pumps (11) are installed and probably a blower (12) for returnwashing by air is also installed.
• the returnwashing pumps cleans the filters by pumping purified sewage from the returnwashing basin through the filters into the procestank.
• the filters can be looked after and maintained from the service- bridge (13).
• Fig. 2 is a top view of the flow (12) along 2 different filters (13). It can be seen that the velocity of flow is increased (14) along the filters, and that a hydraulic suck (15) is created along the filters.
• Fig. 3 is a top view of the velocity of flow (16) along several filters (17). It can be seen that the velocity of flow is increased between the filters. Further it can be seen how the water filtrates through the filters (18) and runs out through the outlet pipe (19).
• Fig. 4 is a top view of several filters arranged in 2 rows (20) and with 2 outletpipes (21) with connected returnwashing pumps (22).
• Fig. 5 shows top views of 6 different gemetries of filters: (23) prism,- (24) drop, (25) lens, (26) double airoplane wing, (27)rectangular, (28) cir cular.
• the filter (27) has opposite the rest of the filters no hydraulic suck along the filter.On the other hand (27) is a favourable simple and cheap geometry of the filter.
• FIG. 6 shows as an example a top view (29) and a sectional view (30) of a more detailed drawing of the filter (23).
• the sides of the filter consists of a perforated plate (24) covered by a filtermembrane (25).
• the filter is connected with other filters by the outletpipe (25).Through this pipe (25) also the returnwashing takes place.
• the filters are hanged by the hangingirons(26).
• the perforated plates (24) are fixed to a framework (27).
• Fig. 7 is a top section of 2 types of filters:

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Life Sciences & Earth Sciences (AREA)
• Biodiversity & Conservation Biology (AREA)
• Microbiology (AREA)
• Hydrology & Water Resources (AREA)
• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Organic Chemistry (AREA)
• Biological Treatment Of Waste Water (AREA)
• Separation Using Semi-Permeable Membranes (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8104337

Family Applications (1)

Country Status (4)

Cited By (3)

Citations (1)

• 1992
  • 1992-11-19 DK DK139092A patent/DK169719B1/da not_active IP Right Cessation
• 1993
  • 1993-11-03 AU AU55604/94A patent/AU5560494A/en not_active Abandoned
  • 1993-11-03 EP EP94900767A patent/EP0669899A1/de not_active Withdrawn
  • 1993-11-03 WO PCT/DK1993/000358 patent/WO1994011311A1/en not_active Application Discontinuation

Patent Citations (1)

Non-Patent Citations (2)

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