• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:

    公开号:NL2004388A
    申请号:NL2004388
    申请日:2010-03-12
    公开日:2010-09-14
    发明作者:Kazuichi Isaka；Yuya Kimura；Tatsuo Sumino
    申请人:Hitachi Plant Technologies；
    IPC主号:
    专利说明:

    WASTEWATER TREATMENT METHOD AND WASTEWATER TREATMENTAPPARATUS
    BACKGROUND OF THE INVENTIONField of the Invention
    The present invention relates to a wastewater treatment method and awastewater treatment apparatus, and particularly relates to a method for treatingwastewater containing ammonium nitrogen and a treatment apparatus therefor.
    Description of the Related Art
    In recent years, a method including denitrification treatment with the use ofanaerobic ammonium-oxidizing bacteria (anaerobic ammonium oxidation method) hasdrawn attention as a method for treating wastewater containing ammonium nitrogen.
    This method includes nitriting the ammonium nitrogen in the wastewater into nitrite withnitrifying bacteria in a nitrification tank, and then simultaneously denitrifying the nitriteand the ammonium nitrogen in the wastewater in the denitrification tank with theanaerobic ammonium-oxidizing bacteria. The method does not need the supply of anorganic substance from the outside for a denitrification reaction, and accordingly canefficiently perform wastewater treatment.
    A simultaneous denitrification reaction in an anaerobic ammonium oxidationmethod proceeds according to the following reaction formula. Accordingly, in order toreliably decompose and remove the ammonium nitrogen in the wastewater, it isnecessary to control the ratio of the ammonium nitrogen and the nitrite nitrogen in thedenitrification tank based on the stoichiometric ratio in the following reaction formula.For this reason, the nitrification rate in the nitrification tank has been needed to bestrictly controlled.
    1.00 NH4 + 1.32 N02 + 0.066 HCO, + 0.13H+ -> 1.02 N2 + 0.26 NO + 0.066 CH2O0.5N0.15 + 2.03 H20
    Then, a method (so-called CANON method) is proposed which allows both ofthe nitrification reaction and the denitrification reaction to proceed in the treatment tankin which the nitrifying bacteria and the anaerobic ammonium-oxidizing bacteria coexist, under an aerobic condition (Japanese Patent Application Laid-Open No. 2001-293494and Third, K.A., Sliekers, A.O., Kuenen, J.G., Jetten, M.S.M., 2001 The CANON system(completely autotrophic nitrogen-removal over nitrite) under ammonium, limitation:interaction and competition between three groups of bacteria. Syst. Appl. Microbiol.24(4), 588-596, for instance). This method can reliably decompose and remove theammonium nitrogen in the wastewater even without strictly controlling the nitrificationrate because the nitrifying bacteria and the anaerobic ammonium-oxidizing bacteriawhich coexist in the same treatment tank tend to keep balance with each other.
    SUMMARY OF THE INVENTION
    However, it has been difficult for the conventional CANON method to maintainthe activities of both of nitrifying bacteria and anaerobic ammonium-oxidizing bacteriawhich coexist in the same treatment tank, and accordingly to rapidly perform thewastewater treatment.
    For instance, the methods described in Japanese Patent Application Laid-OpenNo. 2001-293494 and Third, K.A., Sliekers, A.O., Kuenen, J.G., Jetten, M.S.M., and2001 The CANON system (completely autotrophic nitrogen-removal over nitrite) underammonium, limitation: interaction and competition between three groups of bacteria.
    Syst. Appl. Microbiol. 24(4), 588-596 include treating wastewater under an aerobiccondition for the purpose of activating nitrifying bacteria which are aerobic bacteria, andaccordingly a problem is to lower the denitrification activity of the anaerobicammonium-oxidizing bacteria which are anaerobic bacteria.
    The present invention has been made in view of the above describedcircumstances, and an object thereof is to provide a wastewater treatment method and awastewater treatment apparatus which can rapidly perform wastewater treatment with theuse of nitrifying bacteria and anaerobic ammonium-oxidizing bacteria that coexist in thesame treatment tank.
    A wastewater treatment method according to the present invention is a methodfor treating wastewater containing ammonium nitrogen, including the steps of: oxidizingthe ammonium nitrogen in the wastewater to nitrite with nitrifying bacteria in a treatmenttank in which the nitrifying bacteria and anaerobic ammonium-oxidizing bacteria havinga half-saturation constant of 6.1 mgN/L or more with respect to nitrite coexist; and denitrifying the nitrite formed through the oxidation of the ammonium nitrogen, with theanaerobic ammonium-oxidizing bacteria in the treatment tank, while using theammonium nitrogen contained in the wastewater as a hydrogen donor.
    Here, in the present invention, the "half-saturation constant (mgN/L) withrespect to nitrite" of anaerobic ammonium-oxidizing bacteria is the Michaelis constantwhich is obtained by approximating the relationship between the concentration (mgN/L)of nitrite nitrogen that is a substrate and the rate of consumption (mgN/L/hr) of nitritenitrogen by anaerobic ammonium-oxidizing bacteria, according to the Michaelis-Mentenequation. The "half-saturation constant" is specifically represented by a half-saturationconstant (Michaelis constant) determined in the method described in Example 1, whichwill be described later.
    Conventionally known anaerobic ammonium-oxidizing bacteria have too small ahalf-saturation constant with respect to nitrite to determine because of the precision of ananalytical instrument. In such circumstances, the present inventors have conducted anextensive investigation, and as a result, have found that there exist anaerobic ammonium-oxidizing bacteria which have a very high half-saturation constant (6.1 mgN/L or more)compared to conventional ones. Furthermore, the present inventors have acquired thefinding that such anaerobic ammonium-oxidizing bacteria can maintain denitrificationactivity even under a condition in which the amount of dissolved oxygen (DO) is large.The above described wastewater treatment method is based on the above describedfindings of the present inventors.
    The above described wastewater treatment method employs the anaerobicammonium-oxidizing bacteria that can maintain the denitrification activity even under acondition in which the amount of dissolved oxygen is large, consequently can easilymaintain the activities of both of the nitrifying bacteria and the anaerobic ammonium-oxidizing bacteria which coexist in the same treatment tank, and can rapidly performwastewater treatment.
    In the wastewater treatment method, the concentration of the nitrite in thetreatment tank is preferably maintained at 15 mg/L or more and 250 mg/L or less.
    In the wastewater treatment method, the concentration of ammonium in thetreatment tank is preferably maintained at 3 mg/L or more.
    By maintaining the concentrations of nitrite and ammonium in the treatmenttank in the above described range, the rate of wastewater treatment can be furtherenhanced.
    In the wastewater treatment method, the nitrifying bacteria preferably have ahalf-saturation constant of 15 mgN/L or more with respect to ammonium.
    Here, in the present invention, the "half-saturation constant (mgN/L) withrespect to ammonium" of nitrifying bacteria is the Michaelis constant which is obtainedby approximating the relationship between the concentration (mgN/L) of ammoniumnitrogen that is a substrate and the rate of consumption (mgN/L/hr) of ammoniumnitrogen by nitrifying bacteria according to the Michaelis-Menten equation. The "half¬saturation constant" is specifically represented by a half-saturation constant (Michaelisconstant) determined in the method described in Example 1, which will be describedlater.
    When nitrifying bacteria having a low half-saturation constant with respect toammonium is used, ammonium in a treatment tank is excessively consumed in anitrification reaction, which may affect a denitrification reaction with anaerobicammonium-oxidizing bacteria. By using nitrifying bacteria having a half-saturationconstant of 15 mgN/L or more with respect to ammonium, an excessive consumption ofammonium in a nitrification reaction is prevented, and a denitrification reaction with theanaerobic ammonium-oxidizing bacteria can be allowed to stably proceed.
    In the wastewater treatment method, the nitrifying bacteria and the anaerobicammonium-oxidizing bacteria are preferably immobilized on different carriers from eachother.
    Then, the method can easily control the bacterial loads of the nitrifying bacteriaand the anaerobic ammonium-oxidizing bacteria by adjusting the volume ratio of thenitrification carrier having the nitrifying bacteria immobilized thereon and thedenitrification carrier having the anaerobic ammonium-oxidizing bacteria immobilizedthereon.
    In particular, the carrier is preferably entrapping immobilization pellets.
    When entrapping immobilization pellets are employed as the carrier, the peelingof the biofilm does not occur, which can occur in the case of attachment immobilizationpellets, so the bacterial load can be reliably controlled.
    A wastewater treatment apparatus according to the present invention includes atreatment tank in which nitrifying bacteria and anaerobic ammonium-oxidizing bacteriahaving a half-saturation constant of 6.1 mgN/L or more with respect to nitrite coexist.
    In the wastewater treatment apparatus, the nitrifying bacteria preferably have ahalf-saturation constant of 15 mgN/L or more with respect to ammonium.
    In the wastewater treatment apparatus, the nitrifying bacteria and the anaerobicammonium-oxidizing bacteria are preferably immobilized on different carriers from eachother.
    In the wastewater treatment apparatus, the carrier is preferably entrappingimmobilization pellets.
    The wastewater treatment method according to the present invention can easilymaintain the activities of both of the nitrifying bacteria and the anaerobic ammonium-oxidizing bacteria which coexist in the same treatment tank, by employing anaerobicammonium-oxidizing bacteria having a half-saturation constant of 6.1 mgN/L or morewith respect to nitrite. Accordingly, the method can rapidly perform wastewatertreatment.
    BRIEF DESCRIPTION OF THE DRAWINGS
    Fig. 1 is a block diagram illustrating one example of a wastewater treatmentapparatus according to the present invention;
    Fig. 2 is a block diagram illustrating another example of the wastewatertreatment apparatus;
    Fig. 3 is a table showing the water quality of an ammonium wastewater whichhas been used for acclimating a nitrification carrier;
    Fig. 4 is a graph showing the relationship between the concentration ofammonium and the nitrification rate of acclimated nitrifying bacteria;
    Fig. 5 is a table showing the water quality of a synthetic wastewater which hasbeen used for acclimating a denitrification carrier;
    Fig. 6 is a graph showing a relationship between the concentration of nitrite andthe denitrification rate of acclimated anaerobic ammonium-oxidizing bacteria;
    Fig. 7 is a graph showing the result of a wastewater treatment experiment; and
    Fig. 8 is a table showing the half-saturation constant of acclimated anaerobicammonium-oxidizing bacteria with respect to nitrite.
    DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
    The embodiments according to the present invention will be described belowwith reference to the attached drawings.
    Fig. 1 is a block diagram illustrating one example of a wastewater treatmentapparatus according to the present embodiment. As is illustrated in Fig. 1, a wastewatertreatment apparatus 10 mainly includes: a source water tank 12 in which wastewater tobe treated (source wastewater) is stored; a treatment tank 20 in which the sent wastewaterfrom the source water tank 12 is treated; and a control device 40 which controls eachsection in the wastewater treatment apparatus 10.
    The wastewater which is stored in the source water tank 12 is wastewatercontaining at least ammonium nitrogen, and may contain nutrient salts of nitrogen,phosphorus, carbon and the like, in addition to the ammonium nitrogen. The sourcewater tank 12 is connected to the treatment tank 20, and is configured so that thewastewater can be supplied to the treatment tank 20 therefrom by the pump 14.
    The treatment tank 20 includes a nitrification carrier 22 having the nitrifyingbacteria (ammonium oxidation bacterium) accumulated therein dominantly and adenitrification carrier 24 having the anaerobic ammonium-oxidizing bacteriaaccumulated therein dominantly. Thus, by immobilizing the nitrifying bacteria and theanaerobic ammonium-oxidizing bacteria on different carriers from each other (thenitrification carrier 22 and the denitrification carrier 24), the ratio of bacterial loads ofthe nitrifying bacteria and the anaerobic ammonium-oxidizing bacteria can be easilycontrolled through adjusting the volume ratio of the nitrification carrier 22 and thedenitrification carrier 24. Fig. 1 shows an example in which the nitrifying bacteria andthe anaerobic ammonium-oxidizing bacteria are immobilized on different carriers fromeach other, but the nitrifying bacteria and the anaerobic ammonium-oxidizing bacteriamay be accumulated in the same carrier. For instance, the nitrifying bacteria and theanaerobic ammonium-oxidizing bacteria may be accumulated in the same carrier by thesteps of entrapping and immobilizing any one of the nitrifying bacteria and the anaerobic ammonium-oxidizing bacteria in a carrier and attaching the other bacteria on the surfaceof the carrier.
    The nitrifying bacteria accumulated in the nitrification carrier 22 and theanaerobic ammonium-oxidizing bacteria accumulated in the denitrification carrier 24coexist in the treatment tank 20. Thereby, both of the nitrification reaction due to thenitrification carrier 22 and the denitrification reaction due to the denitrification carrier 24are allowed to proceed in the treatment tank 20, and can decompose ammonium nitrogenin wastewater to nitrogen gas. Here, the nitrification reaction means a reaction whichoxidizes the ammonium nitrogen in the wastewater into nitrite with the use of thenitrifying bacteria, and the denitrification reaction means a reaction which denitrifies thenitrite formed through the nitrification reaction with the anaerobic ammonium-oxidizingbacteria, while using the ammonium nitrogen in the wastewater as a hydrogen donor.
    When wastewater is treated using a treatment tank 20 in which nitrifyingbacteria which are aerobic bacteria and anaerobic ammonium-oxidizing bacteria whichare anaerobic bacteria coexist, it is difficult to rapidly perform wastewater treatmentwhile maintaining the activities of both of the nitrifying bacteria and the anaerobicammonium-oxidizing bacteria. For instance, when wastewater is treated under anaerobic condition for the purpose of activating the nitrifying bacteria which are aerobicbacteria, the denitrification activity of the anaerobic ammonium-oxidizing bacteria whichare anaerobic bacteria decreases.
    The present inventors have found that there exist anaerobic ammonium-oxidizing bacteria having a half-saturation constant of 6.1 mgN/L or more with respect tonitrite, in the course of studying a method of rapidly performing wastewater treatment.Anaerobic ammonium-oxidizing bacteria having such a high half-saturation constanthave not been conventionally known. Generally known anaerobic ammonium-oxidizing bacteria have too small a half-saturation constant with respect to nitrite todetermine because of the precision of an analytical instrument.
    Furthermore, the present inventors have acquired the finding that such anaerobicammonium-oxidizing bacteria can maintain denitrification activity even under acondition in which the amount of dissolved oxygen (DO) is large. This is thought to bebecause anaerobic ammonium-oxidizing bacteria having a large half-saturation constanthave resistance against oxygen.
    Based on the above described findings, bacteria used in the present embodimentas the anaerobic ammonium-oxidizing bacteria to be accumulated in the denitrificationcarrier 24 have a half-saturation constant of 6.1 mgN/L or more with respect to nitrite.The anaerobic ammonium-oxidizing bacteria (bacteria having a half-saturation constantof 6.1 mgN/L or more with respect to nitrite) in the denitrification carrier 24 canmaintain the denitrification activity even under a condition in which the amount ofdissolved oxygen is large, so the activities of both of the nitrifying bacteria and theanaerobic ammonium-oxidizing bacteria which coexist in the treatment tank 20 can beeasily maintained. Accordingly, the method can rapidly perform wastewater treatment.
    Among them, the anaerobic ammonium-oxidizing bacteria to be accumulated inthe denitrification carrier 24 have preferably a half-saturation constant of 15 mgN/L ormore with respect to nitrite, from the viewpoint of further rapidly performing wastewatertreatment.
    The denitrification carrier 24 in which the anaerobic ammonium-oxidizingbacteria having a half-saturation constant of 6.1 mgN/L or more with respect to nitriteare accumulated dominantly can be produced by culturing a carrier containing theanaerobic ammonium-oxidizing bacteria. At this time, it is preferable to culture thecarrier continuously for 3 months or more while maintaining the concentration of thenitrite in the culture tank at 20 to 250 mg/L. Thereby cultured anaerobic ammonium-oxidizing bacteria can acquire a half-saturation constant of 6.1 to 40 mgN/L with respectto nitrite, for instance.
    The nitrifying bacteria to be accumulated dominantly in the nitrification carrier22 are preferably bacteria (AH bacteria) having a large half-saturation constant withrespect to ammonium. In particular, nitrifying bacteria having a half-saturationconstant of 15 mgN/L or more with respect to ammonium are preferable in a point thatthe nitrifying bacteria do not inhibit a denitrification reaction with anaerobic ammonium-oxidizing bacteria, as will be described later.
    When nitrifying bacteria (AL bacteria) having a low half-saturation constantwith respect to ammonium are used, ammonium in the treatment tank is excessivelyconsumed in the nitrification reaction, which may affect the denitrification reaction withthe anaerobic ammonium-oxidizing bacteria. By using nitrifying bacteria having a half¬saturation constant of 15 mgN/L or more with respect to ammonium, an excessive consumption of ammonium in the nitrification reaction is prevented and thedenitrification reaction with the anaerobic ammonium-oxidizing bacteria can be allowedto stably proceed.
    The nitrification carrier 22 in which the nitrifying bacteria having a half¬saturation constant of 15 mgN/L or more with respect to ammonium are accumulateddominantly can be produced by culturing a carrier containing the nitrifying bacteria, forinstance. At this time, it is preferable to culture the carrier continuously whilemaintaining the concentration of the ammonium in the culture tank at 50 mg/L or more.Thereby cultured nitrifying bacteria (AH bacteria) can acquire a half-saturation constantof 10 to 60 mgN/L with respect to ammonium, for instance.
    The nitrification carrier 22 is not particularly limited as long as the nitrifyingbacteria are immobilized on the nitrification carrier 22, and may be immobilizationpellets or a contact filter medium. The nitrifying bacteria to be immobilized on thenitrification carrier 22 may employ bacteria separated from microorganisms in activatedsludge or the like. The nitrification carrier 22 may also employ activated sludgecontaining microbial colonies in which the nitrifying bacteria are proliferated dominantly.
    In addition, entrapping immobilization pellets which have the nitrifying bacteriaentrapped and immobilized in its inner part are preferably used as the immobilizationpellets type of the nitrification carrier 22. The entrapping immobilization pellets, ifbeing used, can reliably control the bacterial load, because an exfoliation of the biofilmdoes not occur, which can occur in the case of the attachment immobilization pellets. Inaddition, when the entrapping immobilization pellets are used, the return of sludge isunnecessary in the acclimation step, so the bacteria can be comparatively easilyacclimated.
    The immobilizing material of the nitrification carrier 22 is not limited inparticular, but includes gels of polyvinyl alcohol, alginic acid, polyethylene glycol andthe like, and plastics such as cellulose, polyester, polypropylene and polyvinyl chloride,for instance. The shape of the nitrification carrier 22 may be, for instance, a sphericalshape, a cylindrical shape or a cubic shape, and may be formed into a porous shape, ahoneycomb shape or a sponge shape. Alternatively, a granule carrier with the use of theself-granulation of a microorganism may be used as the nitrification carrier 22. Contact filter media which can be used for the nitrification carrier 22 can include those madefrom polyvinyl chloride and polyethylene.
    The denitrification carrier 24 is not limited in particular as long as the anaerobicammonium-oxidizing bacteria are immobilized in the denitrification carrier 24, and maybe immobilization pellets or a contact filter medium.
    In addition, the immobilization pellets to be used for the denitrification carrier24 may be entrapping immobilization pellets which have the anaerobic ammonium-oxidizing bacteria entrapped and immobilized in their inner part, or attachmentdepositing immobilization pellets which have the anaerobic ammonium-oxidizingbacteria attached and immobilized on their surface. Among them, the entrappingimmobilization pellet is preferably used as the denitrification carrier 24. Theentrapping immobilization pellets, if being used, can reliably control the bacterial load,because an exfoliation of the biofilm does not occur, which can occur in the case of theattachment immobilization pellets. The entrapping immobilization pellets can reliablyhold bacteria in the treatment tank, and accordingly is suitable for a carrier forimmobilizing precious anaerobic ammonium-oxidizing bacteria therein which areobtained by culture. Furthermore, when the entrapping immobilization pellets are used,the return of sludge is unnecessary in the acclimation step, so the bacteria can becomparatively easily acclimated.
    The immobilizing material of the denitrification carrier 24 is not limited inparticular, but includes gels of polyvinyl alcohol, alginic acid, polyethylene glycol andthe like, and plastics such as cellulose, polyester, polypropylene and polyvinyl chloride,for instance. The shape of the denitrification carrier 24 may be, for instance, a sphericalshape, a cylindrical shape or a cubic shape, and may be formed into a porous shape, ahoneycomb shape or a sponge shape. Alternatively, a granule carrier with the use of theself-granulation of a microorganism may be used as the denitrification carrier 24.Contacting filter media which can be used for the denitrification carrier 24 can includethose made from polyvinyl chloride and polyethylene.
    The total volume of the nitrification carrier 22 and the denitrification carrier 24is preferably 10 to 40% of the volume of the wastewater in the treatment tank 20, andmore preferably is 15 to 25% of the volume. The volume fraction (dominance) of thedenitrification carrier 24 with respect to the total volume of the nitrification carrier 22 and the denitrification carrier 24 in the treatment tank 20 is preferably 25 to 65%. Inparticular, when the water temperature is high (when water temperature is 25 to 37°C, forinstance), the volume fraction (dominance) of the denitrification carrier 24 is preferablyset to 25 to 40%.
    As is illustrated in Fig. 1, the treatment tank 20 is provided with a sensor 26which measures the quality of the wastewater in the treatment tank 20. The sensor 26has such a structure as to be capable of measuring, for instance, the concentrations ofammonium, nitrite and nitrate, the quantity of dissolved oxygen, and pH. The resultmeasured by the sensor 26 is sent to the control device 40, and each section in thewastewater treatment apparatus 10 is controlled on the basis of this measurement result.
    The treatment tank 20 is provided with an air-diffusing device 28, and isstructured so that air is supplied from a blower 30 through the air-diffusing device 28.Thereby, the air-diffusing device 28 aerates and stirs the wastewater in the treatment tank20, and simultaneously can supply dissolved oxygen into the wastewater.
    The control device 40 controls the blower 30 so that the amount of the dissolvedoxygen in the wastewater in the treatment tank 20 is preferably 0.5 to 4.0 mg/L (morepreferably 1.0 to 3.0 mg/L).
    The concentration of the nitrite in the treatment tank 20 is preferably maintainedat 15 to 250 mg/L, and more preferably maintained at 20 to 100 mg/L. In addition, theconcentration of the ammonium in the treatment tank 20 is preferably maintained at 3mg/L or more, and more preferably maintained at 5 mg/L.
    By maintaining the nitrite concentration and the ammonium concentration in thetreatment tank 20 within the above described range, the rate of wastewater treatment canbe further enhanced.
    The nitrite concentration and the ammonium concentration in the treatment tank20 can be adjusted by allowing the control device 40 to control the pump 14 so as tochange the retention time (hydrological retention time) of the wastewater in the treatmenttank 20.
    The wastewater treatment method according to one embodiment of the presentinvention was described in the above, but the present invention is not limited thereto, andof course, can be improved or modified in various ways within a range that does notdeviate from the gist of the present invention.
    For instance, in an example described in the above embodiment, wastewater istreated by using the nitrifying bacteria and the anaerobic ammonium-oxidizing bacteriawhich have been accumulated in the nitrification carrier 22 and the denitrification carrier24, but the wastewater may be treated with activated sludge containing the nitrifyingbacteria and the anaerobic ammonium-oxidizing bacteria.
    Fig. 2 is a block diagram illustrating one example of a wastewater treatmentapparatus which treats wastewater with activated sludge containing the nitrifying bacteriaand the anaerobic ammonium-oxidizing bacteria. In Fig. 2, the same referencenumerals will be put on common components to the wastewater treatment apparatus 10illustrated in Fig. 1, and the description is omitted here.
    The wastewater treatment apparatus 50 illustrated in Fig. 2 is different from thewastewater treatment apparatus 10 in that the wastewater is not treated with thenitrification carrier 22 and the denitrification carrier 24 but is treated with activatedsludge 34 containing the nitrifying bacteria and the anaerobic ammonium-oxidizingbacteria.
    The activated sludge 34 is circulated between the treatment tank 20 and asedimentation tank 32 provided in the rear stage of the treatment tank 20, through areturned sludge pipe 36. The nitrifying bacteria and the anaerobic ammonium-oxidizing bacteria which have been accumulated in the activated sludge 34 coexist in thetreatment tank 20. Thereby, both of a nitrification reaction with the nitrifying bacteriaand a denitrification reaction with the anaerobic ammonium-oxidizing bacteria areallowed to proceed in the treatment tank 20 to decompose ammonium nitrogen in thewastewater to nitrogen gas.
    As in the above described embodiment, bacteria having a half-saturationconstant of 6.1 mgN/L or more (preferably 15 mgN/L or more) with respect to nitrite areused for the anaerobic ammonium-oxidizing bacteria in the activated sludge 34. Suchanaerobic ammonium-oxidizing bacteria can maintain the denitrification activity evenunder a condition in which the amount of dissolved oxygen is large, so the activities ofboth of the nitrifying bacteria and the anaerobic ammonium-oxidizing bacteria whichcoexist in the treatment tank 20 can be easily maintained. Accordingly, the method canrapidly perform wastewater treatment.
    The nitrifying bacteria in the activated sludge 34 are preferably bacteria (AHbacteria) having a high half-saturation constant with respect to ammonium, as in theabove described embodiment. In particular, nitrifying bacteria having a half-saturationconstant of 15 mgN/L or more with respect to ammonium are preferable in that thenitrifying bacteria do not inhibit the denitrification reaction with the anaerobicammonium-oxidizing bacteria.
    In addition, it is preferable to maintain the amount of dissolved oxygen in thewastewater in the treatment tank 20 at 0.5 to 4.0 mg/L (more preferably at 1.0 to 3.0mg/L), to maintain the concentration of the nitrite at 15 to 250 mg/L (more preferably at20 to 100 mg/L), and to maintain the concentration of ammonium at 3 mg/L or more(more preferably at 5 mg/L or more), by allowing the control device 40 to control a pump14 and a blower 30.
    A feature of the present invention will now be described more specifically belowwith reference to Examples. However, the scope of the present invention should not berestrictively interpreted by the specific examples which will be described below.
    Example 1
    Preparation of nitrification carrier 22.
    An activated sludge containing nitrifying bacteria was entrapped andimmobilized with a polyethylene glycol-based gel which had been molded into a cube of3 mm square. These entrapping immobilization pellets in an amount of 0.2 L arecharged into a cylindrical reactor (culture tank) having a volumetric capacity of 2 L. Anitrification carrier 22 was prepared by making ammonium wastewater (inorganicsynthetic wastewater) flow into this reactor and acclimating the nitrifying bacteria at atemperature maintained at 30°C in the reactor for 1 month. Fig. 3 is a table showing thewater quality of the ammonium wastewater used for acclimating nitrifying bacteria.
    When the nitrifying bacteria were acclimated, the wastewater was aerated andstirred, the amount of dissolved oxygen (DO) in the reactor was maintained at 2 to 4mg/L, and also the pH was maintained at 7.5 by the addition of a 5% solution of sodiumbicarbonate. In an early period after the acclimation was started, the flow rate of theammonium wastewater was controlled so that the retention time (hydrological retentiontime) were 24 hours, and then the retention time was shortened and the load wasincreased according to the increase in the activity of the nitrifying bacteria. The above load was controlled so that the concentration of the ammonium in the reactor were 50mg/L or more.
    Fig. 4 is a graph showing the relationship between the nitrification rate of thenitrification carrier 22 which has been prepared in the above described procedure and theconcentration of the ammonium. As a result of having approximated the graph of Fig. 4according to the Michaelis-Menten equation, the obtained half-saturation constant of thenitrification carrier 22 with respect to ammonium was 20 mgN/L.
    Preparation of denitrification carrier 24.
    Anaerobic ammonium-oxidizing bacteria were entrapped and immobilized witha polyethylene-glycol-based gel which had been molded into a cube of 3 mm square.These entrapping immobilization pellets in an amount of 0.2 L are charged into acylindrical reactor (culture tank) having a volumetric capacity of 2 L. In addition, thereactor used had a structure of preventing air from entering the inner part, and wasprovided with a stirrer. A denitrification carrier 24 was prepared by making a syntheticwastewater flow into this reactor and acclimating the anaerobic ammonium-oxidizingbacteria at a temperature maintained at 30°C in the reactor for 6 months. Fig. 5 is atable showing the water quality of the synthetic wastewater which was used foracclimating the denitrification carrier.
    When the denitrification carrier was acclimated, the pH of the wastewater wasmaintained at 7.5 by the addition of an HC1 solution (0.2 N). In addition, in an earlyperiod after the acclimation was started, the flow rate of the ammonium wastewater wascontrolled so that the retention time (hydrological retention time) were 12 hours.Furthermore, the load was controlled so that the concentration of the nitrite in the reactorwere 20 to 250 mg/L.
    Fig. 6 is a graph showing a relationship between the denitrification rate (rate ofconsumption of nitrite) of the denitrification carrier 24 which was prepared in the abovedescribed procedure and the concentration of nitrite. As a result of havingapproximated the graph of Fig. 6 according to the Michaelis-Menten equation, theobtained half-saturation constant of the denitrification carrier 24 with respect to nitritewas 28 mgN/L.
    Examination for nitrification denitrification.
    An examination of wastewater treatment for ammonium wastewater wasconducted by using the nitrification carrier 22 and the denitrification carrier 24 whichwere prepared in the above described procedure. The nitrification carrier 22 and thedenitrification carrier 24 each in an amount of 0.2 L were charged into the same reactoras was used for the preparation of the nitrification carrier 22. The synthetic wastewaterhaving the water quality shown in Fig. 3 was made to flow into this reactor, and thewastewater was treated for 1 month.
    While the wastewater was treated, the amount of the dissolved oxygen in thereactor was maintained at 1.0 to 3.0 mg/L, and the amount of the wastewater flowing intothe reactor was controlled so that the retention time of the wastewater were 8 hours.
    Fig. 7 is a graph showing the water quality of a treated water which was sampledafter 1 month after the start of the wastewater treatment. As is understood from Fig. 7,the ammonium in the wastewater was almost completely treated, and the averageconcentration of the ammonium in the treated water was 6.2 mg/L. The nitrite wasalmost completely treated. The average concentration of nitrite in the treated water was22.4 mg/L, and the average concentration of nitrate which was formed by the anaerobicammonium oxidation reaction was 65 mg/L. The nitrogen-removal rate at this time was2.0 kg-N/nfVday'1.
    Thus, it was confirmed that the wastewater treatment method according to thepresent invention could stably and rapidly perform wastewater treatment.
    Example 2
    Preparation of denitrification carriers 24 having various half-saturation constants.
    Activated sludges containing three types of anaerobic ammonium-oxidizingbacteria were obtained by accumulating and culturing the anaerobic ammonium-oxidizing bacteria with the use of sludges obtained from a sewage treatment plant, atreatment plant of fermentation wastewater in the livestock industry, and a treatmentplant of wastewater in a food factory. The method described in "Acclimation ofanaerobic ammonium-oxidizing bacteria by continuous culture system, Proceedings of38th Annual Meeting of Japan Society on Water Environment, p. 372 (2004))." was usedas the above accumulation and culture method.
    These activated sludges were entrapped and immobilized as in Example 1, andthree types of denitrification carriers 24 (carriers A to C) were prepared by acclimating the respective anaerobic ammonium-oxidizing bacteria. Then, the half-saturationconstants of the respective denitrification carriers with respect to nitrite were measured.
    Fig. 8 is a table showing the measurement result of the half-saturation constants.In Fig. 8, a carrier D means the denitrification carrier 24 which was prepared in Example1. In addition, a sludge E is a sludge prepared by acclimating the anaerobicammonium-oxidizing bacteria while maintaining the concentration of the nitrite in aculture tank at 10 mg/L or less, and the half-saturation constant was measured not in astate of making the anaerobic ammonium-oxidizing bacteria entrapped and immobilizedin a gel, but in a state of making the anaerobic ammonium-oxidizing bacteria attached ona nonwoven cloth.
    It was found from Fig. 8 that the carriers A to D each had a half-saturationconstant of 15 to 40 mgN/L with respect to nitrite. On the other hand, the sludge Eshowed a tendency to have a half-saturation constant with respect to nitrite in the rangeof 0.01 to 1 mgN/L, but cannot be determined because of the precision of an analyticalinstrument.
    Influence of amount of dissolved oxygen.
    The above described carriers A to D were subjected to a wastewater treatmentoperation by using the same reactor as that used in preparing the denitrification carrier ofExample 1 and making synthetic wastewater (synthetic wastewater having water qualityshown in Fig. 5) flow into the reactor. The amount of the denitrification carrier to becharged into the reactor was set to 0.2 L. The operation was continued for about 1month on the condition that the ammonium concentration and the nitrite concentration inthe wastewater of Fig. 5 were 150 mgN/L and 220 mgN/L, respectively, and DO was 0mg/L, and stable data was obtained. Then, DO was increased to 1 to 3 mg/L, and thechange in the nitrogen-removal rate at this time was confirmed. The water temperaturewas set to 30°C, and the HRT was set to 4.8 hours.
    The sludge E was tested by using a reactor having a volume of 0.2 L, which isdescribed in "High nitrogen-removal rate with the use of anaerobic ammonium oxidationmethod, Lectures in Japan Society on Water Environment 7th Symposium, p. 125-126(2004)", and by packing a nonwoven cloth into the reactor, which had made theanaerobic ammonium-oxidizing bacteria attached in the inner part. The concentrationsof NH4-N and N02-N in the source water were each set to 50 mg/L. The water temperature was set to 30°C, and the HRT was set to 4 hours. The operation wascontinued for about 1 month and stable data was obtained. Then, DO was increased to1 to 3 mg/L, and the change in the nitrogen-removal rate at this time was confirmed.
    As a result, in the case of the carriers A to D, there was no change in thenitrogen-removing performance and no influence of the amount of the dissolved oxygenwas found. On the other hand, in the case of the sludge E, the activity remarkablydecreased wrhen the amount of the dissolved oxygen in the source water was adjusted to 1to 3 mg/L, and the activity completely disappeared one week after the amount of thedissolved oxygen had been changed.
    From the result, it was proved that anaerobic ammonium-oxidizing bacteriahaving a half-saturation constant of 6.1 mgN/L or more with respect to nitrite are noteasily affected by the dissolved oxygen.
    权利要求:
    Claims (16)
    [1]
    A waste water treatment method for treating waste water, containing data ammonium nitrogen, comprising the following steps: oxidizing the ammonium nitrogen in the waste water to nitrite with nitrifying bacteria in a treatment tank, wherein the nitrifying bacteria and anaerobeammonium oxidizing bacteria have a half-saturation constant of 6, 1 mg N / L or greater with respect to coexisting nitrite; and denitrifying the nitrite formed by the oxidation of the ammonium nitrogen with the anaerobic ammonium oxidizing bacteria in the treatment tank, and while using the ammonium nitrogen in the waste water as a hydrogen donor.
    [2]
    The waste water treatment method according to claim 1, wherein the concentration of nitrite in the treatment tank is maintained at 15 mg / L or more and 250 mg / L or less.
    [3]
    The waste water treatment method according to claim 1, wherein the concentration of ammonium in the treatment tank is maintained at 3 mg / L or more.
    [4]
    The waste water treatment method according to claim 2, wherein the concentration of ammonium in the treatment tank is maintained at 3 mg / L or more.
    [5]
    The waste water treatment method according to claim 1, wherein the nitrifying bacteria have a half-saturation constant of 15 mg N / L or greater with respect to ammonium.
    [6]
    The waste water treatment method according to claim 4, wherein the nitrifying bacteria have a half-saturation constant of 15 mg N / L or greater with respect to ammonium.
    [7]
    The waste water treatment method according to claim 1, wherein the nitrifying bacteria and the anaerobic ammonium oxidizing bacteria are immobilized on mutually different carriers.
    [8]
    The waste water treatment method according to claim 6, wherein the nitrifying bacteria and the anaerobic ammonium oxidizing bacteria are immobilized on mutually different carriers.
    [9]
    The waste water treatment method of claim 7, wherein the carrier immobilization pellets are included.
    [10]
    The waste water treatment method of claim 8, wherein the carrier immobilization pellets include.
    [11]
    A waste water treatment apparatus comprising: a treatment tank, wherein the nitrifying bacteria and anaerobic ammonium oxidizing bacteria have a half-saturation constant of 6.1 mg N / L or greater with respect to coexisting nitrite.
    [12]
    The waste water treatment device of claim 11, wherein the nitrifying bacteria have a half-saturation constant of 15 mg N / L or greater with respect to ammonium.
    [13]
    A waste water treatment device according to claim 11, wherein the nitrifying bacteria and the anaerobic ammonium oxidizing bacteria are immobilized on mutually different carriers.
    [14]
    A waste water treatment device according to claim 12, wherein the nitrifying bacteria and the anaerobic ammonium oxidizing bacteria are immobilized on mutually different carriers.
    [15]
    The waste water treatment device of claim 13, wherein the carrier immobilization pellets are included.
    [16]
    The waste water treatment device of claim 14, wherein the carrier immobilization pellets are included.
    类似技术:
    公开号 | 公开日 | 专利标题
    NL2004388C2|2010-12-07|Wastewater treatment method and wastewater treatment apparatus.
    NL2004440C2|2011-01-04|Wastewater treatment method and wastewater treatment apparatus.
    Zhang et al.2016|Enhancement of denitrifying phosphorus removal and microbial community of long-term operation in an anaerobic anoxic oxic–biological contact oxidation system
    Feng et al.2012|Effects of packing rates of cubic-shaped polyurethane foam carriers on the microbial community and the removal of organics and nitrogen in moving bed biofilm reactors
    Villaverde et al.2000|Nitrifying biofilm acclimation to free ammonia in submerged biofilters. Start-up influence
    US8574885B2|2013-11-05|Anammox bacterium isolate
    Chung et al.2007|Shortcut biological nitrogen removal in hybrid biofilm/suspended growth reactors
    US6936170B2|2005-08-30|Methods and apparatus for biological treatment of aqueous waste
    NL2004439C2|2011-01-04|Wastewater treatment method.
    US20120097606A1|2012-04-26|Method for treating wastewater containing ammonia nitrogen
    Liu et al.2018|Microbial nitrogen removal of ammonia wastewater in poly |-based constructed wetland: effect of dissolved oxygen
    Chung et al.2005|Comparison of influence of free ammonia and dissolved oxygen on nitrite accumulation between suspended and attached cells
    Kunapongkiti et al.2020|Application of cell immobilization technology to promote nitritation: A review
    JPH08224076A|1996-09-03|Bioreactor
    JP4671178B2|2011-04-13|Nitrogen removal method and apparatus
    Lei et al.2012|The short-term effects of temperature and free ammonia on ammonium oxidization in granular and floccular nitrifying system
    JP2009023890A|2009-02-05|Method and apparatus for producing liquid fertilizer
    Jang et al.2004|Application of biochemical oxygen demand | biosensor for optimization of biological carbon and nitrogen removal from synthetic wastewater in a sequencing batch reactor system
    JP5306296B2|2013-10-02|Waste water treatment apparatus and waste water treatment method
    JP2007237144A|2007-09-20|Nitrogen containing water treatment process and arrangement
    Piechna et al.2017|Respirometric activity of activated sludge and biofilm in IFAS-MBBR system
    Chapanova et al.2007|Effect of temperature and salinity on the wastewater treatment performance of aerobic submerged fixed bed biofilm reactors
    Park et al.2018|Main-stream Partial Nitritation-Anammox | Processes for Energy-efficient Short-cut Nitrogen Removal
    Rout et al.2021|Comparison between a single unit bioreactor and an integrated bioreactor for nutrient removal from domestic wastewater
    Bouteraa et al.2019|Determination of kinetic and stoichiometric parameters in anoxic moving bed biofilm reactor by pulse respirometry
    同族专利:
    公开号 | 公开日
    NL2004388C2|2010-12-07|
    JP5324269B2|2013-10-23|
    JP2010214244A|2010-09-30|
    US20100230348A1|2010-09-16|
    CN101838055A|2010-09-22|
    US8388845B2|2013-03-05|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JP3252888B2|1995-09-11|2002-02-04|日立プラント建設株式会社|Biological nitrogen removal equipment|
    JP2001293494A|2000-04-11|2001-10-23|Kurita Water Ind Ltd|Biological nitrogen removing method|
    JP5150993B2|2000-11-28|2013-02-27|栗田工業株式会社|Denitrification method and apparatus|
    SE521571C2|2002-02-07|2003-11-11|Greenfish Ab|Integrated closed recirculation system for wastewater treatment in aquaculture.|
    US20070218537A1|2004-03-30|2007-09-20|Kumamoto Technology And Industry Foundation|Method For Treating Ammonia-Containing Wastewater|
    JP2006061879A|2004-08-30|2006-03-09|Hitachi Plant Eng & Constr Co Ltd|Waste water treatment method and device|
    CN100548905C|2004-09-30|2009-10-14|栗田工业株式会社|The treatment process of nitrogenous liquid and device|
    US7537698B2|2005-02-28|2009-05-26|Hitachi Plant Technologies, Ltd.|Process and equipment for treating ammonium containing liquid|
    JP4600817B2|2005-03-14|2010-12-22|株式会社日立プラントテクノロジー|Method for treating ammonia-containing water|
    JP2008155086A|2006-12-21|2008-07-10|Ihi Corp|Waste water treatment method and apparatus and microbial agent for waste water treatment|
    JP2008221160A|2007-03-14|2008-09-25|Kobelco Eco-Solutions Co Ltd|Denitrifying treatment device and denitrifying treatment method|CA2748534C|2008-12-28|2014-01-28|Metawater Co., Ltd.|Method and device for removing biological nitrogen and support therefor|
    JP5177802B2|2009-03-25|2013-04-10|株式会社日立プラントテクノロジー|Waste water treatment method and waste water treatment apparatus|
    JP2013230413A|2012-04-27|2013-11-14|Japan Organo Co Ltd|Method and apparatus for treating nitrogen-containing waste water|
    US9255281B2|2012-06-15|2016-02-09|Microvi Biotech Inc.|Bioconversion processes using water-insoluble liquids|
    EP2861539A4|2012-06-15|2016-03-23|Microvi Biotech Inc|Novel biocatalyst compositions and processes for use|
    US9334507B2|2012-06-15|2016-05-10|Microvi Biotech, Inc.|Bioprocesses for making butanol|
    US9752164B2|2012-06-15|2017-09-05|Microvi Biotech, Inc.|Enhanced efficiency ethanol and sugar conversion processes|
    US10375901B2|2014-12-09|2019-08-13|Mtd Products Inc|Blower/vacuum|
    CN111661921A|2020-06-16|2020-09-15|中国科学院生态环境研究中心|Method and device for quickly starting CANON process based on inoculated municipal activated sludge|
    法律状态:
    2014-03-05| SD| Assignments of patents|Effective date: 20140226 |
    2017-11-08| MM| Lapsed because of non-payment of the annual fee|Effective date: 20170401 |
    优先权:
    申请号 | 申请日 | 专利标题
    JP2009061189|2009-03-13|
    JP2009061189A|JP5324269B2|2009-03-13|2009-03-13|Waste water treatment method and waste water treatment apparatus|
    [返回顶部]