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
  • C02F3/26—Activated sludge processes using pure oxygen or oxygen-rich gas
• • 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
  • 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
  • C02F3/30—Aerobic and anaerobic processes
  • C02F3/302—Nitrification and denitrification treatment
• • 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

• This invention concerns a process for treating wastewater , and in a further aspect concerns an apparatus for the treatment of waste water.
• This invention also concerns a treatment plant for treating wastewater.
• the invention may find application in a range of waste water and industrial plants ranging from the domestic to the largest industrial plants and for treatment of even the most polluted waste water and also may find applications in the field of biotechnology and bioprocesses.
• Biological wastewater treatment like other biological processes represents, in limited time and space, what happens in Nature over a long period of time and over a large area. Since its application in the late 19th and early 20th century, the trend has been towards reducing the required time and space, producing better performance and economy in wastewater treatment plants and other bioreactors.
• a process for biological processes and treatment of waste water compromises the steps of simultaneously filtering and aerating the waste water by means of two or more filtering/aerating elements. Each of the filtering/aerating elements is alternately either supplied with pressurised gas, or drained.
• the process has the advantage of treating waste water without a secondary, or even a primary, settling tanks and or other solids/liquid separation devices.
• the process also overcomes the process disruptions caused by filamentous organisms or sludge bulking.
• the process also increases the efficiency, by keeping the microorganism population and concentration high in the bioreactor and or aeration tank.
• Another advantage of the process is that it is adaptable to use in the other aerobic biprocesses and also in some type of water treatment plant as an alternative to aeration and or ozonation plus filtration.
• the pressurised gas may be air or oxygen that may contain ozone or other oxidants.
• the pressurised gas may be supplied in intermittent pulses or in a fluctuating stream or steady stream or any combination of the three flow regimes.
• the ratio of time each filtering/aerating element is used for aeration or filtering may vary between 1 to 99% depending upon operational requirements.
• the frequency with which the filtering/aerating elements are changed from their aeration mode of operation to their filtering mode of operation is also dependant upon operational requirements.
• Filtering/aerating elements can be submerged in the process tank or located externally to the tank.
• an apparatus for the treatment of waste water comprises of two or more filtering/aerating elements each of which has an associated pressurised gas supply and an associated effluent drain.
• the supplies and drains are valved and controlled such that, in use, each element is alternately supplied with pressurised gas or drained. At any given time, one or more selected elements are supplied with the pressurised gas while the reminder are drained.
• filtering/aerating elements are submerged in the process tank, arrangement is made such that pressurised gas coming out of the aerated aerating/filtering elements has optimum cleansing action on the filtering surface of the aerating/filtering elements, and if the aerating/filtering elements are located externally to the process tank, arrangement is made in such a way to guide the liquid flow to the aerating element before passing through filtering elements.
• the aerating/filtering elements by virtue of their alternate aeration and filtering modes of operation, become self cleaning filters.
• the aerator/filter elements may have different shapes and configurations and the configuration may vary from closed end aerator/filter elements to a flow through self-housing multi channel aerator/filter elements.
• the aerator/filter elements can be constructed from various organic and inorganic materials, especially ceramic.
• the pore size may vary between 0.0001 micrometers to 200 micrometers. A smaller pore size means less permeability and as a result greater surface area, more transmembrane pressure and more investment. However, it also results in better effluent quality and more stable process.
• a number of different parameters have to be taken into account when designing a waste water treatment plant or other biological processing plants embodying the invention. These factors include the required economy and efficiency, the required product quality, the size of the plant, The hydraulic and organic load of the waste water and the capacity of the plant. Taking these factors into account enables a plant to be constructed from an array of the aerator/filter elements and open channels.
• the aerator/filter elements may be supplied with pressurised gas and drained by connecting incoming and outgoing pipes together in banks, in series or a combination of two in order to control the operation of a number of elements at a time while increasing cleaning action of the gas bubbles on the surfaces of the filtering aerator/filter elements and/or their channels.
• the depth of the process tanks, the pressure of the gas supply and the gas and liquid flow characteristics of the porous media allows the shape and configuration of the plant to be decided.
• a waste water treatment plant there will advantageously be two tanks connected together and incorporating arrays of aerator/filter elements as described above, internally or externally, to provide a circulation of sludge and waste water between the two tanks, one aerobic for carbonaceous oxidation and nitrification and the other multi-zone for denitrification and anaerobic digestion.
• Both tanks or bioreactors can be packed with high specific surface area media to maintain a long biomass retention time in the bioreactors and increase the volatile solids content of the tanks by means of attached biomass growth on the media surface.
• the treatment plant has the advantage of being very compact, having low sludge production due to its anaerobic zone, being able to remove nitrogen alongside other organic matters, having a high organic loading capability and being easy to run and operate.
• the treatment plant is also capable of treating waste waters with different strength from municipal waste water to the very strong industrial waste waters, aerator/filter array will ensure an efficient aeration, a good quality effluent and high solid retention in the system.
• the aerobic bioreactor not only can perform the nitrification but also can perform a secondary task that is usually done after denitrification to strip the produced nitrogen gas from the effluent. This arrangement also facilitates the pH adjustment between the two bioreactors by the circulation flow. Oxygen consumed for nitrification also will be recovered in the denitrification step.
• the aerobic and multi-zone bioreactors can be suspended growth, attached growth or mixed growth bioreactors utilising a combination of attached and suspended growth.
• Both bioreactors can be sealed but with the anaerobic zone in unaerated bioreactor, this should be a sealed reactor with biogas collection and discharge facility on top and an air-trap in circulation flow pass to avoid explosion hazard by preventing the air from entering aerobic tank.
• a suitable settling device may be located on top of the aerated bioreactor or adjacent to it to decrease the suspended solids content of the liquid before entering the aerator/filter elements array.
• figure 1 is a schematic diagram showing two aerating/filtering elements embodying the present invention
• figure 2 is a schematic diagram showing a cross section of a self-housing multi channel aerating/filtering element embodying the present invention
• figure 3 is a schematic diagram showing some possible shapes of the channels of the self-housing aerating/filtering elements embodying the present invention
• figure 4 is a schematic diagram showing some possible shapes of the self-housing aerating/filtering elements embodying the present invention
• figure 5 is a schematic diagram of an array of aerator/filter elements embodying the present invention
• figure 6 is a schematic diagram of an array of self-housing multi channel aerator/filter elements embodying the present invention
• figure 7 is a schematic diagram of a treatment plant embodying the present invention.
• two aerating/filtering elements 1 and 2 are made of porous materials with specific pore size.
• Pressurised gas is supplied to element 1 through pipe 3 via gas valve 4, and to element 2 through pipe 5 via gas valve 6.
• Effluent, permeated liquid is removed from element 1 through pipe 7 via drain valve 8, and from element 2 through pipe 9 via drain valve 10.
• the elements are immersed in a tank or located externally to the process tank.
• gas valve 4 will be open while drain valve 8 will be closed. Gas will be pumped into the interior of the element and forced through its pores in order to aerate the surrounding liquid.
• the aerator/filter elements may have different shapes and configurations. Further aspect of present invention is one of such configurations. It is especially preferable when the aerator/filter array is located externally to the process tank to use the self-housing multi channel aerator/filter elements in the aerator/filter array.
• aerator/filter elements can be made from different materials especially from inorganic materials like ceramic.
• Figure 2 shows a schematic cross section of a self-housing aerator/filter element.
• Support layer 11 has a much larger pores than the skin layer 12.
• Support layer 11 also occupies most of the element's bulk while skin layer 12 is very thin.
• Skin layer is laid on the surface of the element/module channels.
• Most of the channels like channel 13 are channels having the skin layer with the small pores. The liquid to be filtered is passing through these channels.
• Some channels like channel 14 do not have skin layer and have larger pores the same as support layer. Thus the filtrate that is passing through pores of the skin layer of channel 13 into the support layer's larger pores, flows into the channel 14 and subsequently is removed from the element through channel 14.
• each self-housing aerator/filter element may have 2 or as many as hundreds of channels of which the majority are with the skin layer laid on their surface.
• the channels of self-housing aerator/filter elements may have different shapes depending on the usage and other operational parameters.
• Figure 3 shows some possible shapes of the channels.
• a thin transition layer also may be placed between support layer and skin layer.
• the transition layer has a pore size larger than the skin layer and smaller than that of support layer.
• 2 or more aerator/filter element may form a bigger aeration/filtration array or module to provide more aeration/filtration area in each unit.
• Self-housing elements may have different shapes depending on the usage and operational parameters as shown in figure 4.
• two or more elements is required.
• the liquid flow always is guided to the aerating element first to increase the cross-flow velocity in the filtering elements channels by injecting a substantial volume of gas bubbles into the liquid flow through aerating elements while reducing the viscosity of the flow and increasing the transverse mixing effect by lateral air bubble movements in the filtering elements channels.
• the porous elements may placed horizontally or vertically to improve cleaning action of gas-bubble-flow inside filtering elements channels.
• a set of valves which are connected to a time controller provides the necessary means for shifting the aeration task from one element to another while guiding the liquid flow to the aerating element first.
• Figure 5 shows elements 1 and 2 included in an array of further elements separated from each other by open channels indicated generally by 16. Liquid is able to flow through the open channels which allows it to mix effectively with the gas being injected into the liquid by aerating elements. If the array submerged inside the process tank, the mixed liquid and gas bubbles flows from open channel 16 directly into the bulk liquid inside the tank. When the array in figure 6 is located externally to the process tank, then the aerated liquid from channel 16 is collected and guided to the bottom of the process tank by a pipe. Another pipe carries the liquid from the tank to the other open end of channel 16 and other open channels in the array.
• Exchanging the aerating and filtering operation between two neighbouring rows of elements assists in cleaning the surfaces and the pores of the elements, and carries floes up to prevent cake formation.
• FIG. 6 shows a schematic of a arrangement of self-housing multi channel aerator/filter elements in an array.
• Aerator/filter elements 17, 18, 19 and 20 are made of porous materials with specific pore size and surface area.
• Effluent, permeated water or filtered product is removed from element 19 through pipe 36 via drain valve 35, and from element 20 through pipe 45 via drain valve 44. While one of the elements is operating as an aerator the other will be operating as a filter. For example when element 19 is operating as an aerator, gas valve 37 is open while drain valve 35 is closed. Gas is pumped into the channels of element 19 through its porous structure and is forced through its pores in order to aerate the waste water or broth which is flowing in the channels inside element 19. Pipe 34 is carrying waste water/broth into the clement 19 and pipe 39 is carrying away the aerated waste water/broth from the element 19.
• Gas bubbles in the aerated water that is passing through the channels of element 20, can eliminate or decrease the chance of cake formation over the channels walls.
• Elements 17 and 18 also filtering the aerated water/broth along with element/module 20. After aerated water/broth is passed through elements 20,17 and 18 via valves 22 and 27, will be passing through pipe 52 via valve 31 and will leave the aerator/filter array towards the process tank through pipe 51. After a designated period of time, aerating task will be shifted to element 20 and while elements 17, 18 and 19 are acting as filters. Switching the mode of operation from filtering to aeration will result in cleaning off the cake that is formed over the surface of the channels of element 20 while it acts as a filter.
• the pressurised gas can often unblock the pores, for stronger effect it is more effective to change the gas supply volume for short times and in specific intervals. Supply gas can also oxidise and sterilise the structure of the aerating element.
• each element may consist of several elements that are connected together in a parallel way and then each of this multi elements acts as one element in the array.
• Influent 56 enters a conditioning tank 57 and nutrients 58 may be added to the tank if needed.
• Pump 59 pumps the waste water to the upper portion of bioreactor 54 through pipe 60.
• Bioreactor 54 is packed with a high specific surface area media with a high void percentage. Waste water is getting mixed with the circulation flow 61 which is also entering bioreactor 54 at its upper portion. The mixed flow moving downward inside bioreactor 54. The dissolved oxygen and some of the organic substrate in the flow will be consumed by the microorganisms that has grown on the media surface inside bioreactor 54 in the aerobic zone.
• bioreactor 54 As the flow moves further down, the dissolved oxygen content of the flow decreases until it reaches to a low level and microorganisms begin to utilise nitrate as the electron donor thus an anoxic zone forms. Finally when little oxygen or nitrate is left in the downward flow inside bioreactor 54, anaerobic microorganisms dominate the population of the biomass and the anaerobic zone forms. As a result of anaerobic activity, biogas will be produced in this zone. Biogas bubbles move up ward due to its lower density than water. Biogas will leave the bioreactor 54 via pipe 62 to the processing and consumption point. Some of the detached biomass will settle in the hopper 63 located right in the bottom of the bioreactor 54.
• pipe 64 is for anaerobic sludge wastage that may be done at specific intervals or continuously.
• the down ward flow inside bioreactor 54 leaves bioreactor 54 through pipe 65.
• the pH adjustment takes place in pipe 65 by pH sensor 66 and alkalinity addition pipe 67.
• Pipe 65 guides the circulation flow to the lower part of bioreactor 55.
• Air or oxygen that may contain specific dose of ozone enters bioreactor 55 in the form of two phase flow through pipe 68. Oxygen transfer from gas bubbles into the liquid inside pipe 78 and bioreactor 55 provides oxygen that is vital for carbonaceous oxidation and nitrification in the bioreactor 55.
• the tubing between the aerator/filter array 81 and the bottom of the bioreactor 55 can be long enough to let the liquid flow inside pipe 78 reaches to or near its oxygen saturation point when entering the bioreactor 55.
• This tubing may have larger cross-section area to lower the superficial flow velocity to maximise the gas transfer in the tube.
• Circulation flow 61 leaves bioreactor 55 in its upper portion. Circulation flow 61 passes through air trap 69, valve 70 and pump 71 before entering bioreactor 54.
• a settling device 72 that may be located in the upper portion of the bioreactor 55 may separate solids from effluent 73.
• Pump 75 delivers the over flow 76 of settling device to the aerator/filter elements array 81 through pipe 77. If no settling device is used, liquid from top of the bioreactor 55 is pumped to the aerator/filter elements unit 81 via pipe77. Effluent 79 or treated water, is drawn from the aeration filtration unit 81.
• Pipe 68 is carrying flow 70 That contains air plus ozone to the bottom of bioreactor 55. Ozone generator 73 and air supply pipe 82, suppling gas to the aerating elements in aerator/filter array 81.
• Aerator/filter elements array 81 can be of different configurations but it is preferable to use configurations in figure 5 and or configuration shown in figure 6.
• the other option is to place the aerator/filter elements array inside bioreactor 55 by omitting pipes 76, 77 and 78 and pump 75. In this case it is preferable to use configuration of the aerator/filter array shown in figure 5.

Landscapes

• 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)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Biological Treatment Of Waste Water (AREA)
• Aeration Devices For Treatment Of Activated Polluted Sludge (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Activated Sludge Processes (AREA)
• Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
• Treatment Of Water By Oxidation Or Reduction (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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Citations (6)

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• 1996
  • 1996-09-06 AU AUPO2182A patent/AUPO218296A0/en not_active Abandoned
• 1997
  • 1997-09-08 JP JP51205598A patent/JP2001505480A/ja active Pending
  • 1997-09-08 CA CA 2264915 patent/CA2264915A1/en not_active Abandoned
  • 1997-09-08 WO PCT/AU1997/000577 patent/WO1998009918A1/en not_active Application Discontinuation
  • 1997-09-08 EP EP97937358A patent/EP0958249A4/de not_active Withdrawn

Patent Citations (6)

Non-Patent Citations (1)

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