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WO1998000370A1 - Nitrification biologique a basse temperature d'eaux usees - Google Patents

Nitrification biologique a basse temperature d'eaux usees Download PDF

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Publication number
WO1998000370A1
WO1998000370A1 PCT/US1997/010907 US9710907W WO9800370A1 WO 1998000370 A1 WO1998000370 A1 WO 1998000370A1 US 9710907 W US9710907 W US 9710907W WO 9800370 A1 WO9800370 A1 WO 9800370A1
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Prior art keywords
nitrification
sidestream
mainstream
sludge
wastewater
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PCT/US1997/010907
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English (en)
Inventor
Peter Kos
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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
    • 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

  • the present invention relates to wastewater treatment processes, and more particularly to an improved nitrification process wherein nitrifiers are produced in a sidestream and directed therefrom into a mainstream where they act to carry out nitrification at low sludge retention time values.
  • the present invention relates to a nitrification process wherein nitrifiers are produced in a sidestream independently of a mainstream treatment process, and the sidestream produced nitrifiers are continuously or periodically transferred to the mainstream to participate witn mainstream produced nitrifiers to carry out a mainstream nitrification process
  • a secondary stream or source is identified that possesses a relatively high concentration of ammonia and this secondary stream is itself subjected to a nitrification process completely independent of the mainstream process
  • an abundant supply of supplemental nitrifiers are produced and these supplemental nitrifiers are conveyed or transferred to the mainstream where they perform a nitrifying function. This results in a very efficient nitrifying process due to the abundant supply of supplemental nitrifiers m the sidestream.
  • nitrification is very expensive particularly from a capital cost viev ⁇ om . That is, in order to efficiently nitrify using a conventional nitrification process, the capacity and size of the treatment basin must be relatively large and that in itself translates into substantial expense.
  • the present invention has discovered an approach that will reduce the size of nitrification treatment basins and will accordingly reduce the overall cost of building adequate treatment facilities for nitrification Simply put, the present nitrification process suggests that the age of the sludge circulated through the mainstream can be substantially reduced compared to the sludge age that is standard m conventional nitrification processes.
  • the process design for sludge age in a conventional nitrification process calls for the sludge age to be designed to be at least 200% of the critical or minimum sludge age That is the minimum Typically, standard engineering practice would call for a safety factor of 2.0, or at least, a safety factor approaching 2.0.
  • Another object of the present invention resides in the provision of a process or system for a biological wastewater treatment process wherein supplemental or additional nitrifiers are produced in a sidestream nitrification zone and the produced supplemental nitrifiers are continuously or periodically transferred from the sidestream nitrification zone to the mainstream where the supplemental nitrifier effectuate nitrification in the mainstream process.
  • Still a further object of the present invention resides in the provision of a biological wastewater treatment process having an enhanced nitrification capability especially m cold climates.
  • Another object of the present invention resides in the provision of a biological nitrification process for treating wastewater that is particularly adapted to be compatible with existing wastewater treatment facilities and which does not require large scale capital outlays for additional equipment and facilities
  • a further object of the present invention is to provide a biological nitiification process that is extremely stable and which is capable of nitrification at relatively low sludge ages which will enable the aeration tanks utilized by the nitrification process to be designed for a relatively low capacity compared with conventional nitrification processes
  • Another object of the present invention s to provide a nitrification process design wherein the sludge age is maintained less than 200% of the critical or minimum sludge age of a conventional nitrification process operated under comparable wastewater temperature conditions
  • Figure 1 is a schematic illustration of the enhanced biological nitrification process and system of the present invention.
  • Figure 2 is a schematic illustration of the enhanced biological nitrification process ana system of the present invention showing a particular process and system design.
  • Figure 3 is a graph which illustrates the relationship between sludge age, effluent ammonia concentration, and nitrifier concentration m a conventional activated sludge process.
  • Figure 4 is a graphical illustration of the relationship between sludge age, effluent ammonia concentration, and nitrifier concentration in the ennanced biological nitrification process and system of the present invention.
  • Figure 5 is a graphic illustration showing various relationships between sludge age and temperature for a conventional nitrification process .
  • the goal of nitrification and denitrification in a wastewater treatment process is to remove ammonia nitrogen, NH 3 -N.
  • This is oasically a two-step process, referred to as nitrification and denitrification.
  • the nitrification step basically entails converting the ammonia nitrogen, NH 3 -N, to nitrite or nitrate, both referred to as NO x .
  • the biological nitrification process of the present invention is shown therein and indicated generally by the numeral 10
  • influent wastewater is directed along a mainstream 12 through a mainstream biological treatment process 14
  • the mainstream biological treatment process can include a series of various treatment zones including one or more anaerobic zones, one or more aerobic (oxici zones, or one or more anoxic zones.
  • the mainstream biological treatment process 14 would include at least a nitrification zone for converting ammonia nitrogen NH,-N to N0 Basically, the mainstream biological treatment area or zones 14 would produce a treated or purified effluent that could be discharged into a creek, river, lake, etc .
  • the present invention entails a sidestream nitrification system indicated generally by the numeral 16.
  • the sidestream nitrification system 16 produces supplemental nitrifiers that are conveyed or transferred to the mainstream 12 where the supplemental nitrifiers aid or assist m the mainstream nitrification process.
  • the present invention entails directing a sidestream 15 into a sidestream nitrification zone or reactor 13 It is contemplated that the sidestream being fed or directed into the sidestream nitrification zone 13 would have a relatively high ammonia concentration compared to the ammonia concentration found m the influent wastewater being directed into and through the mainstream process. For example, it is contemplated that the concentration of ammonia in sidestream 15 would be m the range of 400 to 2,000 mg/1 This is compared to a concentration of 10 to 60 mg/1 of ammonia nitrogen that one finds in a typical influent wastewater
  • the temperature of the ammonia r ch solution found m the sidestream nitrification zone 13 would be elevated in many cases relative to the temperature of the wastewater passing through the mainstream biological treatment area 14.
  • the sidestream temperature or the temperature within the sidestream nitrification zone 13 would be in the range of 20-35°C This of course, tends to increase the reaction rate within the sidestream nitrification zone 13 and because the input stream 15 is high m ammonia concentration, it follows that an abundant supply of biological nitrifiers are produced or cultivated.
  • supplemental nitrifiers These biological nitrifiers are referred to in some cases herein as supplemental nitrifiers because they are directed through line 11 or 18 back to the mainstream 12
  • the supplemental nitrifiers combine with produced in the mainstream to greatly enhance and accelerate the mainstream nitrification process
  • Excess biological sludge full of nitrifiers accumulated in the sidestream nitrification zone 13 can be directed to the mainstream treatment zone 14 via line 11.
  • the high ammonia concentrated solution being treated there can be nitrified m many conventional ways
  • biological nitrification can be carried out by activated sludge process, trickling filters, rotating biological contactors, sequencing biological reactors and so forth and so on
  • biological nitrification is carried out in the sidestream through any conventional nitrification process.
  • the pH should be controlled so as to fall within the range of 6 5 to 8 5 During nitrification, alkalinity is consumed ana therefore alkalinity needs to be added into the sidestream nitrification zone 13 m amounts equal to approximately 4mg of alkalinity as CaCO, (calcium carbonate) for each mg of ammonia-nitrogen
  • alkalinity as CaCO, (calcium carbonate) for each mg of ammonia-nitrogen
  • Other chemicals that can be used to control alkalinity and pH in the sidestream are soda ash, sodium hydroxide, and lime.
  • the mainstream treatment area includes at least one aeration tank 56. This of course is utilized for mainstream nitrification. As pointed out above, it should be appreciated that the mainstream treatment area could include any number of other treatment zones such as anaerobic, aerobic, or anoxic.
  • the treated wastewater is directed through a secondary clarifier 60 that directs a treated or purified effluent out outlet line 62.
  • Separated sludge is directed out the bottom of secondary clarifier 60 and a portion of it is returned to the mainstream via a return activated sludge line 64.
  • the return activated sludge is mixed with the incoming influent wastewater in line 54 to form a mixed liquor that is subsequently treated in the mainstream treatment area or the mainstream treatment zone or zones (in this case the aeration tank 56) .
  • Some of the sludge directed from the secondary clarifier 60 is referred to as excess activated sludge or waste sludge and that is directed through line 68 to a digester 70 or another sludge stabilization process.
  • primary sludge collected by the primary clarifier 52 is directed into line 66 and into the digester 70. Both the primary sludge and excess activated sludge is held within the digester 70 a selected time period for purposes of digestion. Once the digestion process has been completed the digested sludge is directed to a sludge dewatering station 72.
  • dewatering liquid which is directed out line 74 and dewatering liquid which is directed through line 76 to a sidestream nitrification system or zone 78.
  • dewatering liquid is subjected to nitrification and as pointed out above, the dewatering liquid would have a high concentration of ammonia nitrogen and would typically be at an elevated temperature compared to the influent wastewater passing through the mainstream of the process.
  • supplemental biological nitrifiers are produced in the sidestream nitrification system 78 and these supplemental nitrifiers are conveyed to the mainstream via line 84.
  • supplemental nitrifiers combined with nitrifiers produced in the aeration tank 56 and the combined nitrifiers act to effectuate complete and effective nitrification in the mainstream and particularly in aeration tank 56 of the example shown. It should be also noted that excess biological sludge full of nitrifiers held m the sidestream nitrification system 78 can be conveyed to the mainstream and particularly through the aeration tank 56 via line 80.
  • Nitrifiers production decreases with increasing mean cell residence time and therefore, the sidestream nitrification system has to be designed and operated at the low mean cell residence times (sludge age)
  • the sidestream nitrification system 78 should be operated at mean cell retention times below 20 days (where nitrifiers production is approximately one-half of the maximum theoretical yield) preferably at 10 days where nitrifiers production is approximately two-thirds of the maximum theoretical yield.
  • the advantage of the process of the present invention is that the present process designed for nitrification will enable one to design the mainstream nitrification for a relatively low sludge age, for example approximately five days or lower in the northern climates with wastewater temperatures approximately 10°C
  • a conventional nitrification process design where the design is based on a sludge age of eleven to fourteen days
  • the aeration tanks must be much larger in size especially to afford a reasonable safety factor
  • the nitrification process of a typical conventional activated sludge process is quite unstable once the sludge age gets down close to the critical sludge age value which is about five to six days at 10° C.
  • the sidestream nitrification reactor is assumed to have a hydraulic detention time of one day and operates at four days of sludge age and at a temperature of 25 °C
  • the mainstream aeration tank is assumed to be a completely mixed reactor having a hydraulic detention time of six hours. In this example, approximately twenty- five (25%) percent of all ammonia nitrogen available for nitrification is in the dewatering liquid that is directed to the sidestream nitrification reactor and seventy-five (75%) percent of the ammonia nitrogen is in the mainstream wastewater.
  • the temperature of the sewage within the mainstream is assumed to be 10°C which represents a typical winter temperature of sewage in the northern parts of the United States.
  • X concentration of Nitrosomonas cells (nitrifiers)
  • ⁇ c Mean cell residence time (sludge age, sludge retention time, SRT)
  • ⁇ N maximum possible nitrifier growth rate, day x , environmental conditions of pH, temperature, and DO,
  • This process design method also defines the minimum solids retention time at which conventional nitrification ceases by:
  • u minimum solids retention time, days, for nitrification at pH, temperature and DO.
  • Figures 3 and 4 the relationship of sludge age with respect to nitrifier concentration and effluent ammonia concentration for a conventional activated sludge process and for the process of the present invention is shown m Figures 3 and 4.
  • Figure 3 shows a conventional activated sludge process and particularly the nitrification process thereof.
  • the sidestream nitrification reactor of the present process can operate at sludge ages of 5 days and achieve approximately ninety (90%) percent nitrification (that is ammonia concentrations in the effluent of 2 mg/1) Therefore, the wastewater treatment process of the present invention allows nitrification in the aeration tank or reactors having approximately 6 hours of hydraulic detention time and operating at sludge ages of 5 days This should be compared with a conventional activated sludge process which would require approximately twice the tank capacity operating at sludge ages of at least 11 to 14 days.
  • the biological wastewater treatment process of the present invention and particular the nitrification process thereof has many advantages over a conventional activated sludge process
  • the process of the present invention is much more stable than a conventional activated sludge process and does not result in total failure due to an oversight or error m judgment.
  • the process of the present invention has the ability to quickly recover once the effluent concentration of the ammonia nitrogen starts to reach or surpass a critical level That is not the case with the conventional activated sludge process depicted m Figure 3 That process is very unstable and once the sludge age passes a critical point the entire process becomes unstable and will fail to achieve nitrification.
  • Figure 5 is a graphic illustration of the data tabulated in Table 3.
  • critical SRT is plotted as a function of temperature.
  • Design SRT for safety factor 1.5 is also plotted as a function of temperature.
  • the values set forth in Table 3 and plotted in Figure 5 are for a conventional nitrification process
  • the minimum design SRT tabulated in Table 3 and plotted in Figure 5 is based on a safety factor (SF) of 1.5 or 150%
  • the present invention entails a discovery, a discovery that the particular process disclosed herein can be efficiently operated at a sludge age (SRT) below a normal or standard sludge age for a conventional nitrification process.
  • SRT sludge age
  • design SRT design sludge age
  • a conventional nitrification process is a simple mainstream process such as the well- known Bardenpho process or the process disclosed in the Barnard patent, U.S. Patent No. 3,964,998, the disclosure thereof being herein expressly incorporated by reference
  • Table 3 and the graph illustration of Figure 5 explores the critical or minimum sludge age at various temperatures for conventional nitrification processes As discussed herein, the determination of critical or minimum sludge age for a conventional mainstream nitrification process, such as that disclosed in the Barnard patent (U.S. 3,964,998), is highly dependent upon temperature.
  • the minimum sludge age increases with temperature For example, at a wastewater design temperature of 5°C, the minimum or critical sludge age for a conventional nitrification process is 9 4 days On the other hand, for a wastewater design temperature of 15 C 'C, the minimum or critical sludge age for the mainstream of a conventional nitrification process is 3.5 days These are critical or minimum sludge ages - not design sludge ages. It is well -accepted m the wastewater industry that one cannot base a nitrification process design on minimum or critical sludge age.
  • a safety factor (SF) must be applied Universally, the applied safety factor (SF) is typically 2.0 or at least 1.5.
  • FIG. 5 there is shown a plot of critical or minimum sludge age (critical SRT) as a function of temperature.
  • critical SRT critical or minimum sludge age
  • Table 3 illustrates, the critical or minimum sludge age for a conventional nitrification process decreases as the wastewater design temperature increases Taking the minimum acceptable safety factor of 1.5, and assuming an effluent ammonia concentration of 2 mg/1, a shaded region is formed below the design sludge age line of Figure 5 based on a 1.5 safety factor. Consequently, beginning with design wastewater temperatures of 5°C, the design slu ⁇ ge age for conventional nitrification processes begins at 17.6 days.
  • the design SRT for a conventional nitrification process begins at approximately 10.7 days
  • the design sludge age for a conventional nitrification process begins at approximately 6.6 days. It is important to appreciate that this is the lower boun ⁇ ary line (i.e. a safety factor of 1.5 or 150%) for design criteria relating to design sludge age m conventional nitrification processes. It can be seen that for each temperature, that these design sludge age values are approximately twice (200%) of the critical or minimum sludge age
  • This essentially means that the process of the present invention can be carried out by maintaining or controlling the sludge age within the mainstream of the present process at a value less than about 200% of the critical or minimum sludge age of a conventional nitrification process
  • comparing sludge age of the present process with a conventional process it is to 3e understood that the comparison is intended to compare the sludge age of a conventional process being carried out under the same conditions ifor example - temperature)
  • the sludge age within a process designed for 5°C wastewater conditions is maintained below 17.6 days
  • the design sludge age for the mainstream of the present process is maintained or controlled below 10 7 days
  • the upper boundary line for design sludge age is fixed at 200% of the critical or minimum sludge age for a conventional nitrification process operated under the same temperature conditions
  • the design sludge age of the present invention would be substantially below this boundary line. Accordingly, the facilities for handling the wastewater influent to be treated by the present process will be substantially less m size and cost than the facilities that would be required m cases involving conventional nitrification processes
  • sludge age refers to the so-called oxic sludge age, that is the sludge age necessary for nitrification in the oxic or aerated zones only.

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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)

Abstract

L'invention porte sur un procédé et un système de nitrification biologique d'eaux usées. Le procédé comporte un traitement du flux principal et un traitement du flux secondaire, ce dernier produisant des agents nitrificateurs supplémentaires qui sont déversés dans le flux principal. Le traitement du flux secondaire consiste à faire passer un flux de liquide à forte teneur en ammoniac, tel que du liquide d'égouttage (76), et à température élevée, dans une zone de nitrification (78) où circule le flux secondaire. Les agents nitrificateurs obtenus sont déversés dans le flux principal (56) ou ils renforcent la nitrification et permettent une exploitation à faible temps de rétention des boues, temps pendant lequel la nitrification resterait faible si les agents nitrificateurs n'étaient pas déversés dans le flux principal.
PCT/US1997/010907 1996-06-28 1997-06-24 Nitrification biologique a basse temperature d'eaux usees Ceased WO1998000370A1 (fr)

Applications Claiming Priority (2)

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US67272696A 1996-06-28 1996-06-28
US08/672,726 1996-06-28

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WO1998000370A1 true WO1998000370A1 (fr) 1998-01-08

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000005177A1 (fr) * 1998-07-24 2000-02-03 Dhv Water B.V. Procede de traitement d'eaux usees contenant des composants specifiques tel que de l'ammoniac
CN112424129A (zh) * 2018-05-11 2021-02-26 Bl 科技公司 用膜曝气生物膜侧流预处理以从高强度废水中去除氨
CN112645454A (zh) * 2020-12-07 2021-04-13 重庆理工大学 一种持续生物强化污水处理设备

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5098572A (en) * 1987-09-24 1992-03-24 Lyonnaise Des Eaux Method and apparatus for increasing sludge concentration in water purification installations
US5356537A (en) * 1992-05-28 1994-10-18 No Sludge, Inc. Method and apparatus for treating waste water

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5098572A (en) * 1987-09-24 1992-03-24 Lyonnaise Des Eaux Method and apparatus for increasing sludge concentration in water purification installations
US5356537A (en) * 1992-05-28 1994-10-18 No Sludge, Inc. Method and apparatus for treating waste water

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
TENDAJ-XAVIER, MARTA, "Biologisk Behandling Av Rejekyvatten Fran Centrifugering Av Rotslam", ROYAL TECHNICAL UNIVERSITY DISSERTATION, August 1985, pages 15-18. *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000005177A1 (fr) * 1998-07-24 2000-02-03 Dhv Water B.V. Procede de traitement d'eaux usees contenant des composants specifiques tel que de l'ammoniac
US6602417B1 (en) 1998-07-24 2003-08-05 Dhv Water B.V. Process for the treatment of waste water containing specific components e.g. ammonia
CN112424129A (zh) * 2018-05-11 2021-02-26 Bl 科技公司 用膜曝气生物膜侧流预处理以从高强度废水中去除氨
CN112645454A (zh) * 2020-12-07 2021-04-13 重庆理工大学 一种持续生物强化污水处理设备

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