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
  • C02F3/1242—Small compact installations for use in homes, apartment blocks, hotels or the like
  • C02F3/1247—Small compact installations for use in homes, apartment blocks, hotels or the like comprising circular tanks with elements, e.g. decanters, aeration basins, in the form of segments, crowns or sectors
• • 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
  • C02F3/22—Activated sludge processes using circulation pipes
  • C02F3/223—Activated sludge processes using circulation pipes using "air-lift"
• • 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
  • C02F3/301—Aerobic and anaerobic treatment in the same reactor
• • 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
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
  • Y02A20/20—Controlling water pollution; Waste water treatment
  • Y02A20/208—Off-grid powered water 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

• the present invention relates to a method of removing nitrogen and its compounds from water by means of a biological process in an activated sludge suspension, as well to an apparatus for realizing said method.
• a denitrification process is used for the removal of nitrates and nitrites .
• the nitrates and the nitrites serve as a source of oxygen for microorganisms and they are reduced by its metabolism down to a gaseous nitrogen.
• the microorganisms consume a suitable biodegradable substrate and oxidize the same using the received oxygen.
• the microorganisms themselves may serve as a substrate for the denitrification in the process of a so called endogenic respiration, e.g. in case the supplying of the biodegradable substrate is irregular.
• anoxide conditions are necessary, i.e. there must be a lack of molecular oxygen in the medium.
• the microorganisms orientate on the consumption of the same and they change to the denitrification only when there is no more oxygen.
• the anoxide conditions are usually reached by preventing any access of oxygen when the concentration of microorganisms is sufficient, and said microorganisms themselves create anoxide conditions by consuming the present oxygen.
• the biological processes may be employed either with microorganisms attached to a solid basis or with microorganisms being in an activated sludge suspension
• the aeration serves mostly the purpose of an aerobic activating water purification and at the same time to create conditions for a nitrification of ammonia and organic nitrogen, i.e. to transform any remaining nitrogenous contamination to nitrates .
• the result of connection of the denitrification and the nitrification is the biological removal of all nitrogen compounds from water.
• the activated sludge, separated from the purified water flowing away, is usually also returned to the denitrification.
• said denitrification has a number of disadvantages .
• the activated sludge is in the state of suspension.
• the suspension of the sludge is ensured automatically due to the aeration.
• the suspension of the sludge is secured usually by mechanical mixing.
• an agitator and a source of movement e.g. an electric motor with a gearing - is necessary for the mechanical mixing.
• Said mechanical parts increase the investment costs and in case of any defect the repair is complicated due to their arrangment in the denitrification zone.
• Another disadvantage of the above denitrification is represented by a limitation for the concentration of the activated sludge in the denitrification only to the values given by mixing of the components entering the denitrification, which limits the rate of the denitrification related to a volume unit of the denitrification zone.
• the activated biological sludge is led into the denitrification zone by streaming from below upwards, wherein the streaming rate in the direction from below upwards is slowed down at least in the lower part of the denitrification zone.
• the superfluous activated sludge in the form of flocks is led away from the upper part of the denitrification zone and then, it is subjected to an aeration, separated form water and returned into the lower part of the denitrification zone.
• the streaming rate in the upwards direction is slowed down at least in the lower part of the fluidized layer, wherein the water containing nitrates, the activated sludge, and the substrate, which is biologically oxidized during the denitrification, are led into the lower part of the fluidized layer. It is advantageous that after the denitrification, the water and the superfluous activated sludge are led away from the upper part of the fluidized layer and the activated sludge, which has been led away, is freed from the sticking nitrogen bubbles by means of an aeration, it is separated from the purified water and it is returned into the lower part .
• the essence of the apparatus for performing the method according to the invention consist in that the apparatus comprises an upwards widening denitrification zone, into the lower part of which an admission for the water containing nitrates, an admission for the activated sludge and an admission for the substrate, which has been biologically oxidized during the denitrification, mouth.
• the denitrification zone is interconnected in its upper part with the activation zone, which comprises aeration elements and is interconnected with the separation zone, in the upper part of which an outlet for the purified water is arranged, the separation zone being provided with a withdrawal for separated sludge which is provided with a means for a forced movement and mouths into the lower part of the denitrification zone.
• the withdrawal for separated sludge is positioned in the lower part of the separation zone near to its interconnection with the activation zone, the outlet for the water with nitrates from the activation zone designed to return it into the denitrification zone being realized by means of identical structural members, and that the admission for the water containing nitrates, the admission for the activated sludge and the admission for the substrate, which has been biologically oxidized, are realized as a common admission.
• Fig. 1 depicts a cross section of the apparatus and Fig . 2 the ground plan of the apparatus .
• the apparatus consists of a vertical cylindrical tank with a casing 1 and a bottom 2 , wherein an upwards funneling denitrification zone 5. is formed in said tank by a vertical partition wall 2 . a first semi-conical wall 4. and a part 2__ of the bottom 2 between the lower edges of the partition wall 2 and of the first semi-conical wall 4. Further, there is a separation zone 2 formed by the vertical partition wall 2 and a second semi-conical wall £ in the other part of the cylindrical tank. An activation zone 2 is formed between the casing 1 and both semi-conical walls 4 and _.. An inlet _.
• the water level 11 is determined by the position of the inlet __ for purified water.
• Said interconnection 12. is formed by two circular apertures, the upper edges of which are positioned above the water level 11 and the lower edges below the water level li.
• the interconnection 12 may be formed by other means, e.g. by recessions in the upper edge of the first semi-conical wall 4.
• An opening 12 is prepared in the lower part of the second semi-conical wall £, said opening 12 providing the interconnection between the separation zone 2 and the activation zone £.
• a basket 15. is positioned in the upper part of the semi-circular piping 14, wherein a sewage water admission
• the air-lift pump 12 is substantially inserted into the semi-circular piping ___ and leads below the basket 12 (Fig.l) .
• a pressurized air supply 1 is provided in the lower part of the air-lift pump 12.
• Aeration elements 2Q_ are positioned in the lower part of the activation zone 2 near to the bottom 2 .
• a large bubble auxiliary aeration element 21 is positioned in the lower part of the denitrification zone 2 near to the part 21 of the bottom 2 .
• nitrogen compounds e.g. urea, ammonia, nitrogen in organic materials, and further various biodegradable materials, which will be further designated as the substrate.
• the sewage water i.e. the water with biodegradable substrate, after flowing through the basket 12, is mixed with water, which contains nitrates and returned activated sludge and which is led by air-lift pump 12 below the basket 12-
• the mixture of water, biodegradable substrate, nitrates, and activated sludge is led by the semi-circular piping H into the lower part of the denitrification zone 2, where the direction of its movement is changed so that said mixture in the denitrification zone 2 flows upwards .
• the flow rate becomes lower in the upward direction.
• Another part of the substrate is retained by the activated sludge and consumed later in the period, when no substrate is supplied from outside.
• the water from which nitrates and most of the biodegradable substrate has been removed overflows from the denitrification zone 2 through the interconnection 12 into the activation zone 2- Particles of the activated sludge, at which the bubbles of separated nitrogen produced by denitrification stick, are raised upwards from the fluidized layer of the sludge blanket in the denitrification zone 2 as they are held up by said bubbles, and they are entrained by the flowing streaming water through the interconnection 12 into the activation zone 8.
• the water in the activation zone is saturated with oxygen and a streaming is formed, which keeps the activated sludge in suspension and mixes the same evenly in the whole activation zone 2-
• the mixed activated sludge oxidizes all available nitrogen compounds to nitrates and removes the rest of the dissolved biodegradable materials from the water.
• an aerobic stabilization of the activated sludge occurs.
• the pressurized air is blown into the air-lift pump 12 by the supply 12, gets through the air-lift pump 12 upwards and creates there the known air-lift pumping effect.
• the activating mixture consisting of water with nitrates and mixed activated sludge is sucked from the adjacent part of the activation zone 2 by means of the mouth 17 through the opening 12 and is led below the basket 12 and through the semi-circular piping 14 into the lower part of the denitrification zone 2, as described above.
• the air-lift pump 12 serves as the source of positive movement, by means of which a closed circulation circuit is provided, said circuit serving the purpose of returning the nitrates formed in the activation zone 2 back into the denitrification zone 2-
• the sewage water flows through the admission 12 in shocks and irregularly.
• the nitrates are led through the described circulation circuit from the activation zone 2 into the denitrification zone 2, where they are removed by the denitrification.
• a biodegradable substrate for the denitrification serves first of all the substrate retained before in the activated sludge in the fluidized layer of the sludge blanket in the denitrification zone 2- In case, the retained substrate has been exhausted, further denitrification proceeds on the endogenic respiration of the activated sludge.
• the concentration of the nitrates in the activation zone 2 is lowered constantly down to a very low value .
• the activating mixture flows through the formed fluid layer of sludge blanket and the activated sludge is retained and attaches to the flocks in the sludge blanket .
• the formed large flocks fall in the separation zone 2 down and they are drained off by means of the mouth 12 through the air-lift pump 12 into the semi-circular piping 2A, through which they get into the lower part of the denitrification zone 2- So the separated sludge returns into the denitrification zone 2.
• the purified water flows away from the separation zone 2 through the inlet 2 for purified water into the outlet 10.
• the purified water remaining in the separation zone 2 is then the water of the activating mixture in that part of the activation zone 2, which is adjacent to the opening 12, and it has got through the denitrification zone 2 and activation zone 2 before and from which biodegradable materials and nitrogen compounds have been removed in that way.
• the sewage water flowing into the apparatus through the admission 12 is striped of biodegradable materials and nitrogen compounds and the water flows out from the apparatus through the outlet 12 as a purified water.
• the activated sludge which is constantly led in due to the operation of the air-lift pump 18. accumulates in the fluid layer of the sludge blanket in the denitrification zone 2, and only the sludge in suspension goes over into the activation zone 2, and the superfluous sludge comes into the activation zone 2 only after the sludge blanket has filled the whole denitrification zone 2, it could happen in case of a smaller amount of the activated sludge in the whole apparatus, e.g.
• An auxiliary aeration element 21 is provided to prevent such cases and it is installed in the denitrification zone 2 near to the part 21 of the bottom 2- At starting the auxiliary aeration element 21 the air going out of it breaks all incidental accumulations, gets them from the part 21 of the bottom 2 in suspension and mixes the fluidized layer in the denitrification zone 2 so that the activated sludge goes over from the denitrification zone 2 into the activation zone 2 along with the flowing water. So a short-time, sporadic switching-on of the auxiliary aeration element 21 may serve as a prevention against the above mentioned failures .
• the results of its test operation are provided in the Table below, wherein the results have been won in a series of withdrawals from the operation of ten test units used in family houses, where the number of inhabitant ranged from 2 to 7 persons.
• the functional spaces of said test unit had the following volumes: the denitrification zone 2 - 0,25 m 3 , the separation zone 2 - 0,4 m 3 , the activation zone 2 - 1,1 m 3 .
• the achieved average values correspond to the removal of 91,5% of nitrogen and 98,5% of B0D s .
• the method and apparatus according to the invention have numerous advantages .
• the concentration of the activated sludge in the fluidized layer of the sludge blanket in the denitrification zone 2 is higher than the concentration of the activated sludge in the activation zone 2, which results in the fact that the denitrification rate in a volume unit is higher than in a mechanically mixed denitrification zone.
• the substrate, which is brought into the denitrification zone 2 and serves the denitrification, is retained there in the fluidized layer of the sludge blanket so that its utilization for denitrification is higher than in a mechanically mixed denitrification zone.
• the method and apparatus according to the invention is not limited to the waste water purification and to the described exemplifying apparatus only. It is possible to use it for other purposes, e.g. to remove nitrates from a potable water, where a hygienically suitable organic compound, e.g. alcohol, sugar, and so on, will be added as the substrate. Also the apparatus for realizing the method according to the invention may be of various internal arrangment, wherein the basic principle of the invention is essential, i.e.
• the apparatus comprises an upwards extended denitrification zone, in the lower part of which an admission for water containing nitrates, activated sludge and a substrate for denitrification is provided. It is not essential whether the admission for the water containing nitrates, the activated sludge and the substrate for denitrification is common, as it is in the described exemplifying apparatus, or there are independent admissions for the individual components into the lower part of the denitrification zone 2- All kinds of utilization of the basic principle of the above described inventive idea do not digress from the essence of the invention.

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• 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)
• Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)

Applications Claiming Priority (3)

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• 1997
  • 1997-05-14 CZ CZ971479A patent/CZ147997A3/cs unknown
• 1998
  • 1998-05-13 WO PCT/CZ1998/000023 patent/WO1998051626A1/en not_active Application Discontinuation
  • 1998-05-13 EP EP98916800A patent/EP0981500A1/de not_active Withdrawn
  • 1998-05-13 AU AU70280/98A patent/AU7028098A/en not_active Abandoned
  • 1998-05-13 CA CA002288642A patent/CA2288642A1/en not_active Abandoned
  • 1998-05-13 SK SK1512-99A patent/SK151299A3/sk unknown
  • 1998-05-13 PL PL98336931A patent/PL336931A1/xx unknown

Non-Patent Citations (1)

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