CA1043477A - Method and apparatus for nitrification of sewage - Google Patents
Method and apparatus for nitrification of sewageInfo
- Publication number
- CA1043477A CA1043477A CA218,823A CA218823A CA1043477A CA 1043477 A CA1043477 A CA 1043477A CA 218823 A CA218823 A CA 218823A CA 1043477 A CA1043477 A CA 1043477A
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- zone
- aeration
- sewage
- vessel
- fermentation zone
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- Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
- Treatment Of Sludge (AREA)
- Activated Sludge Processes (AREA)
Abstract
Method and Apparatus for Nitrification of Sewage ABSTRACT OF THE DISCLOSURE
An activated sludge sewage treatment apparatus and process in which nitrification is maintained at high effectiveness by providing additional nitrifying bacteria as required from cultures grown under very favorable growth conditions.
An activated sludge sewage treatment apparatus and process in which nitrification is maintained at high effectiveness by providing additional nitrifying bacteria as required from cultures grown under very favorable growth conditions.
Description
~0~3477 This invention is directed to an apparatus and method for improving nitrification in the "single sludge" ac~ivated sludge process.
In recent years, due to tha change in wastewater compositions, arising from changes in agricultural and household practices, the need for control of the elements and compounds of phosphorus and nitrogen in wastewster management has arisen. The primary concerns with respect to nitrogen and phosphorus in wastewater are eutrophication of streams and ponds, oxygen sag (depletion), low ammonia toleration by fish and nitrate contamination of potable water supplies.
The present invention treats that portion of the wastewater treatment problem involving nitrogen compounds. The optimum disposal of nitrogen, present as amines and ammonia in raw wastewater, is into the atmosphere as free nitrogen. However, this ideal solution can be provided only at considerable expense, and there is wide acceptance of less ideal processes for G onia management. The following processes fall into this latter group:
A. Air stripping of G onia in tower or pond.
B. Conversion of G onia by genus Nitrosomonas in the sewage treatment plant to nitrite, which is concur-` 20 rently converted to the rully oxidized nitrate by genus Nitrobacter.
C. Removal of G onia by ion exchange, clinoptilolite ~ resin and other natural and synthetic resins.
.
The air stripping of G onia is relatively expensive due in part to the cost of erecting the tower or the cost of providing a suitable pond with associated apparatus. In addition, where freezing weather occurs, the process becomes inoperative.
~, .
", - : ,. , : , ~0434~7 The removal of ammonia by ion exchange is also relatively high in cost due to the need for constructlng a resin exchange structure and providing such resins, which are quite costly. Further, the resins tend to foul and backwashing the resins often produces wsste products which present their own peculiar disposal problems.
The process designated B above may be carried out, as a practi-cal matter, in a two-sludge system in which a first aeration tank is devoted to carbonaceous compound removal and a second aeration tank carries out nitrification. In the two-sludge system, having a second biological reaction system specific to nitrlfication, a decreased wasting of excess sludge of the second biological reaction system is practiced in order to build up the population of nitrifying organisms. This necessary practice diminishes the capacity of the system. Further, it is obvious that since the two-sludge system requires two tank structures, the co~t t 15 will be roughly double the cost of the single tank required for the treat-`~ ment of carbonaceous pollutants.
i Proce88 B of the above list becomes Lhe least costly solution when it takes place in the ~ame aerated basin which is simultaneously ~ removing carbonaceous pollutants. This is known as the "single sludge y 20 sygtem". In this single sludge system, where the biological nitrification reaction is carried out in con~unction with the biological oxidation of carbonaceous pollutants, it has been recognized that nitrification is the ~ limiting reaction. Thus~ the nitrification reaction, although it proceeds, { wlll nevertheless be slowed down by the less than optimum conditions of pH, temperature and essential nutrient proportions which prevail in the single sludge system tank. Operation of the single sludge system has been precarious and uncertain heretofore due to the relatively poor conditions prevalllDg ln tbc single sludg sy te~ taDk a- to theoe paraaeters, leading 1~43477 to a depleted population of viable organisms available for carrying out the desired nitrification reactions. This result is sometimes expressed as "washout" of nitrifying organisms.
It should be understood that in these biological reaction systems for nitrification, the biological reactions are particularly sensitive to temperature. Thus, in warm weather the reactions proceed giving good results, but in cold weather the reactions may be brought nearly to a halt. The warm weather permits a hi8h growth of the species of bacterial life required to carry out the reactions, while the cold weather reduces reproduction of the bacteria to the point where insuffi-cient biological life is present to carry out the reactions at a useful level.
It is clear that if the single sludge system can be made con`sistently effective and efficient, there will be many applications for such a system.
It is the ob~ect of this invention to provide a single sludge system with improved nitrification capability.
~ It is another ob~ect of this invention to provide a consistently .~
high level of nitrifying organisms in a single sludge system to assure adequate nitrification.' Other ob~ects and advantages of this invention will, in part, `i be obvious and will, in part, appear hereinafter. For a better under-standing of the nature and ob~ects of the inventlon, reference should be had to the follo~ing detailed description and to the drawing, in which:
The Figure is a schematic view of a sewage treatment system arranged to carry out the process of the inventlon.
Generally speaking, this invention is directed to an improvement 1D the actlvated aludge proceaa whereiD a oeparate fet=eDtatioQ ~one ia ,,; , - , : . : ,,. .-. . ~ , . .. " . . ~
~l)43477 provided for growing nitrifying bacteria under optimum conditions, and supplying said nitrifying bacteria to the aeration tank of a single sludge system as required to maintain the nitrification reaction at an effectlve level.
S More specifically, the present i~vention involves establishing, in a vessel, optimum conditions for the growth of nitrifying bacteria by means of appropriate temperature control, pH control and provision for the introduction of adequate nutrients and growth promoters. This fermentor vessel employs, as a growth medium, a portion of the sewage stream feeding the aeration tank of the activated sludge system. In the favorable environ-ment of the fermentor vessel there is, at all times, a ~arge population of nitrlfying bacteria available for supply to the aeration tank. The supply of nitrifying bacteria to the aeration tank may be either intermittent or continuous depending upon the situation prevailing in the aeration tank.
The contents of the fermentor vessel are to be maintained at a temperature in the range from about 30 to about 35C, for example, 30C + 1, and at a pH in the range from about 7 to about 9 by controlled additions of acid or alkaline constituents, e.g., solutions of H2C03 or NaOH. Since the nitrifying bacteria are organisms that necessarily depend upon inorganic ~ 20 raw materials for metabolism and synthesis (obligate autotrophs), the n carbon source required therefor is C02 or HC03-. The basic source of these carbon compounds is the sewage feed, but additional carbon compounds can be introduced from other sources in order to carry out the aim of maintaining optimum growth conditions in the fermentor vessel. It is known that additions of Ca(OH)2 and NH4+ are capable of producing "explosions"
j in a nitrifier population. Introduction of these compounds may therefore ~ be made to produce routinely high yields of organisms in the fermentor ¦ vessel.
In the drawings, a ~ingle sludge system is illustrated comprising ~ an aeration tank or zone 10 and a secondary clarifier or settling zone 20.
, , .
The operation of this portion of the system is essentially conventional in that a sewage waste stream is introduced into the aeration tank lO
through line 12. Air for the biological reaction in the aeration tank is introduced through line 13 and the overflow liquid is then passed through conduit 16 to the secondary clarifier 20. Sludge from the secondary clarifier exits for disposal through line 23 and the effluent, including nitrates, leaves for further treatment through line 24. A
recycled sludge from the secondsry clarifier 20 is routed back to the aeration tank lO through line 22.
The fermentor zone 50 includes the fermentor vessel 30, an inlet conduit 32 for diverting a portion of the waste stream in line 12 to the fermentor vessel 30, an agitator 35, a condui~ for introducing additional nutrients and growth promotars 36, a heating device 34 for maintainlng the contents 31 of fermentor vessel 30 in the optimum temper-ature range and a conduit 33 for introducing a portion of the contents 31 of the reactor vessel 30 into the aeration tank 10.
The operation of the system will be readily understood from ; examination of the drawing. Thus the contents of the aeration tank undergo biological reaction in the aerated environment provided by air introduced through line 13. Reactions which occur in ~he tank 10 involve both the carbonaceous compounds and the nitrogenous compounds. While in general the conditions in the aeration tank 10 are maintained insofar as it is posaible as optimum for treatment of the carbonaceous compounds, . conditions may well widely depart from optimum conditions for the repro-i 25 duction of nitrifying organisms. Thus, the aeration tank may tend tobecome seriously depleted insofar as the nitrifying bacteria are concerned.
When lt is found that the nitrifying bacteria population in the aeration tank is likely to fall below the required level, a quantity of the contents 31 of the fermentor vessel 30, rich in nitrifying bacteria, can be introduced into the aeration tank through conduit 33. This introduction - , . .
~, . . . . .. .. . . .
of nitrifying bacteria from tank 30 may be either on an intermittent or a continuous basis.
It is sometimes desirable to introduce air directly intG the contents 31 of fermentation vessel 30 or into the sewage feed strea~ 32 to aid the growth of nitrifying bacteria. Air introduced at the bottom of vessel 30 would serve to agitate the vessel contents.
The conduit 33 has been described as feeding directly into the aeration tank 10. However, part or all of the inoculum from tank 30 may alternatively be introduced into the aeration tank 10 via the feed line 12 through the branch line 38 which has control valve 42 positioned therein. By in~ecting the inoculum into feed line 12 ~ust before it dis-charges into the aeration tank, good mixture with the incoming feed i8 achieved and the problem of distribution of inoculum in the aeration tank does not arise. Conduit 33 is provided with valve 41 to permit control ,~ 15 of the flow from vessel 30. Valve 43 is also provided in conduit 33 to effect diversion of part or all of the flow in conduit 33 into branch conduit 38.
t The sewage flowing into the system invariably contains a population of nitrifying bacteria, so that there is a constant influx of nitrifying bacteria at some level into the primary clarifiers, the aeration tank and the fermentor vessel. It is desirable in nitrification to achieve a level of NH3 no greater than 1 mg/l in the aeration tank overflow. The NH3 content of the overflow may be monitored to determine when additional inoculum is required. The aeration basin feed stream may contain as much as 60 mg/l of NH3 or even more.
For the purpose of giving those skilled in the art a better uDder~tandlng of ~he lnventlon, the folloving Bxemple i~ offered:
'; , i~43477 EXAMPLE
A 6ewage flow of 1,000 gpm (gallons per mlnute) feeds an aeration tank having a capacity of 360,000 gallons. A portion of the feed, amounting to 100 gpm is diverted through a ferment~ation branch having a 10,000 gallon fermentor vessel therein. The fermentor vessel is maintained at a temperature of 30C + 1 and a pH of from 7 to 9 is maintained by appropriate additions of H2SO4, HCl, C02, Na2CO3 or NaOH.
During a period in which sewage temperatures in the aeration tank fluctuated between 50F (10C) and 60F (15.5C), a contlnuous flow of 100 gpm i9 maintained from the fermentor vessel to the aeration tank.
Nltrlficatlon in the single aeration tank is effective to reduce NH3 concentratlons from lnltial levels of 25 to 40 mg/l NH3 in the aeration basin feed stream to less than l ppm NH3 in the tank overflow.
As described, thetemperature of the contents of the fermentor vessel must be maintained in the temperature range of from about 30 to about 35C. In most situations this will mean providing heatlng means to prevent the temperature of the vessel contents from dropping below the desired temperature range. However, ln some circumstances, as when the fermentor vessel 18 located in a heated building, or under peak growth condltions, the vessel contents may tend to exceed the necessary tempera-ture range and, ln that case, appropriate cooling means will be required.
Emphasis has been placed in this description on the use of a fermentation zone for growing nitrifying bacteria which can then be supplied to the aeration zone of a "single sludge" system in order to malntain an adequate nitrifying bacteria population in that zone. It is contemplated that the fermentation zone of the invention may also be used ln connectlon wlth the "two-sludge" system, ln whlch case, the nltrlfylng bacterla produced ls supplled to the vessel or vessels devoted to the nltrlflcatlon reaction. In this way, the effective operatlng i 30 sea~on of the "two-sludge" system can be extended in northern climates.
It will be noted that the relatively small fermentor vessel represents a substantial cost saving over the large second tank required in the two-sludge system, not only in terms of equipment cost, but in terms of land usage as well.
Although the present invention has been described with particu-lar reference to preferred embodiments, it will be apparent to those skilled in the art that variations and modifications may be made without departing from the Qssential spirit and scope of the invention. It is intended to include all such variations and modifications.
... . .. . . . . .
In recent years, due to tha change in wastewater compositions, arising from changes in agricultural and household practices, the need for control of the elements and compounds of phosphorus and nitrogen in wastewster management has arisen. The primary concerns with respect to nitrogen and phosphorus in wastewater are eutrophication of streams and ponds, oxygen sag (depletion), low ammonia toleration by fish and nitrate contamination of potable water supplies.
The present invention treats that portion of the wastewater treatment problem involving nitrogen compounds. The optimum disposal of nitrogen, present as amines and ammonia in raw wastewater, is into the atmosphere as free nitrogen. However, this ideal solution can be provided only at considerable expense, and there is wide acceptance of less ideal processes for G onia management. The following processes fall into this latter group:
A. Air stripping of G onia in tower or pond.
B. Conversion of G onia by genus Nitrosomonas in the sewage treatment plant to nitrite, which is concur-` 20 rently converted to the rully oxidized nitrate by genus Nitrobacter.
C. Removal of G onia by ion exchange, clinoptilolite ~ resin and other natural and synthetic resins.
.
The air stripping of G onia is relatively expensive due in part to the cost of erecting the tower or the cost of providing a suitable pond with associated apparatus. In addition, where freezing weather occurs, the process becomes inoperative.
~, .
", - : ,. , : , ~0434~7 The removal of ammonia by ion exchange is also relatively high in cost due to the need for constructlng a resin exchange structure and providing such resins, which are quite costly. Further, the resins tend to foul and backwashing the resins often produces wsste products which present their own peculiar disposal problems.
The process designated B above may be carried out, as a practi-cal matter, in a two-sludge system in which a first aeration tank is devoted to carbonaceous compound removal and a second aeration tank carries out nitrification. In the two-sludge system, having a second biological reaction system specific to nitrlfication, a decreased wasting of excess sludge of the second biological reaction system is practiced in order to build up the population of nitrifying organisms. This necessary practice diminishes the capacity of the system. Further, it is obvious that since the two-sludge system requires two tank structures, the co~t t 15 will be roughly double the cost of the single tank required for the treat-`~ ment of carbonaceous pollutants.
i Proce88 B of the above list becomes Lhe least costly solution when it takes place in the ~ame aerated basin which is simultaneously ~ removing carbonaceous pollutants. This is known as the "single sludge y 20 sygtem". In this single sludge system, where the biological nitrification reaction is carried out in con~unction with the biological oxidation of carbonaceous pollutants, it has been recognized that nitrification is the ~ limiting reaction. Thus~ the nitrification reaction, although it proceeds, { wlll nevertheless be slowed down by the less than optimum conditions of pH, temperature and essential nutrient proportions which prevail in the single sludge system tank. Operation of the single sludge system has been precarious and uncertain heretofore due to the relatively poor conditions prevalllDg ln tbc single sludg sy te~ taDk a- to theoe paraaeters, leading 1~43477 to a depleted population of viable organisms available for carrying out the desired nitrification reactions. This result is sometimes expressed as "washout" of nitrifying organisms.
It should be understood that in these biological reaction systems for nitrification, the biological reactions are particularly sensitive to temperature. Thus, in warm weather the reactions proceed giving good results, but in cold weather the reactions may be brought nearly to a halt. The warm weather permits a hi8h growth of the species of bacterial life required to carry out the reactions, while the cold weather reduces reproduction of the bacteria to the point where insuffi-cient biological life is present to carry out the reactions at a useful level.
It is clear that if the single sludge system can be made con`sistently effective and efficient, there will be many applications for such a system.
It is the ob~ect of this invention to provide a single sludge system with improved nitrification capability.
~ It is another ob~ect of this invention to provide a consistently .~
high level of nitrifying organisms in a single sludge system to assure adequate nitrification.' Other ob~ects and advantages of this invention will, in part, `i be obvious and will, in part, appear hereinafter. For a better under-standing of the nature and ob~ects of the inventlon, reference should be had to the follo~ing detailed description and to the drawing, in which:
The Figure is a schematic view of a sewage treatment system arranged to carry out the process of the inventlon.
Generally speaking, this invention is directed to an improvement 1D the actlvated aludge proceaa whereiD a oeparate fet=eDtatioQ ~one ia ,,; , - , : . : ,,. .-. . ~ , . .. " . . ~
~l)43477 provided for growing nitrifying bacteria under optimum conditions, and supplying said nitrifying bacteria to the aeration tank of a single sludge system as required to maintain the nitrification reaction at an effectlve level.
S More specifically, the present i~vention involves establishing, in a vessel, optimum conditions for the growth of nitrifying bacteria by means of appropriate temperature control, pH control and provision for the introduction of adequate nutrients and growth promoters. This fermentor vessel employs, as a growth medium, a portion of the sewage stream feeding the aeration tank of the activated sludge system. In the favorable environ-ment of the fermentor vessel there is, at all times, a ~arge population of nitrlfying bacteria available for supply to the aeration tank. The supply of nitrifying bacteria to the aeration tank may be either intermittent or continuous depending upon the situation prevailing in the aeration tank.
The contents of the fermentor vessel are to be maintained at a temperature in the range from about 30 to about 35C, for example, 30C + 1, and at a pH in the range from about 7 to about 9 by controlled additions of acid or alkaline constituents, e.g., solutions of H2C03 or NaOH. Since the nitrifying bacteria are organisms that necessarily depend upon inorganic ~ 20 raw materials for metabolism and synthesis (obligate autotrophs), the n carbon source required therefor is C02 or HC03-. The basic source of these carbon compounds is the sewage feed, but additional carbon compounds can be introduced from other sources in order to carry out the aim of maintaining optimum growth conditions in the fermentor vessel. It is known that additions of Ca(OH)2 and NH4+ are capable of producing "explosions"
j in a nitrifier population. Introduction of these compounds may therefore ~ be made to produce routinely high yields of organisms in the fermentor ¦ vessel.
In the drawings, a ~ingle sludge system is illustrated comprising ~ an aeration tank or zone 10 and a secondary clarifier or settling zone 20.
, , .
The operation of this portion of the system is essentially conventional in that a sewage waste stream is introduced into the aeration tank lO
through line 12. Air for the biological reaction in the aeration tank is introduced through line 13 and the overflow liquid is then passed through conduit 16 to the secondary clarifier 20. Sludge from the secondary clarifier exits for disposal through line 23 and the effluent, including nitrates, leaves for further treatment through line 24. A
recycled sludge from the secondsry clarifier 20 is routed back to the aeration tank lO through line 22.
The fermentor zone 50 includes the fermentor vessel 30, an inlet conduit 32 for diverting a portion of the waste stream in line 12 to the fermentor vessel 30, an agitator 35, a condui~ for introducing additional nutrients and growth promotars 36, a heating device 34 for maintainlng the contents 31 of fermentor vessel 30 in the optimum temper-ature range and a conduit 33 for introducing a portion of the contents 31 of the reactor vessel 30 into the aeration tank 10.
The operation of the system will be readily understood from ; examination of the drawing. Thus the contents of the aeration tank undergo biological reaction in the aerated environment provided by air introduced through line 13. Reactions which occur in ~he tank 10 involve both the carbonaceous compounds and the nitrogenous compounds. While in general the conditions in the aeration tank 10 are maintained insofar as it is posaible as optimum for treatment of the carbonaceous compounds, . conditions may well widely depart from optimum conditions for the repro-i 25 duction of nitrifying organisms. Thus, the aeration tank may tend tobecome seriously depleted insofar as the nitrifying bacteria are concerned.
When lt is found that the nitrifying bacteria population in the aeration tank is likely to fall below the required level, a quantity of the contents 31 of the fermentor vessel 30, rich in nitrifying bacteria, can be introduced into the aeration tank through conduit 33. This introduction - , . .
~, . . . . .. .. . . .
of nitrifying bacteria from tank 30 may be either on an intermittent or a continuous basis.
It is sometimes desirable to introduce air directly intG the contents 31 of fermentation vessel 30 or into the sewage feed strea~ 32 to aid the growth of nitrifying bacteria. Air introduced at the bottom of vessel 30 would serve to agitate the vessel contents.
The conduit 33 has been described as feeding directly into the aeration tank 10. However, part or all of the inoculum from tank 30 may alternatively be introduced into the aeration tank 10 via the feed line 12 through the branch line 38 which has control valve 42 positioned therein. By in~ecting the inoculum into feed line 12 ~ust before it dis-charges into the aeration tank, good mixture with the incoming feed i8 achieved and the problem of distribution of inoculum in the aeration tank does not arise. Conduit 33 is provided with valve 41 to permit control ,~ 15 of the flow from vessel 30. Valve 43 is also provided in conduit 33 to effect diversion of part or all of the flow in conduit 33 into branch conduit 38.
t The sewage flowing into the system invariably contains a population of nitrifying bacteria, so that there is a constant influx of nitrifying bacteria at some level into the primary clarifiers, the aeration tank and the fermentor vessel. It is desirable in nitrification to achieve a level of NH3 no greater than 1 mg/l in the aeration tank overflow. The NH3 content of the overflow may be monitored to determine when additional inoculum is required. The aeration basin feed stream may contain as much as 60 mg/l of NH3 or even more.
For the purpose of giving those skilled in the art a better uDder~tandlng of ~he lnventlon, the folloving Bxemple i~ offered:
'; , i~43477 EXAMPLE
A 6ewage flow of 1,000 gpm (gallons per mlnute) feeds an aeration tank having a capacity of 360,000 gallons. A portion of the feed, amounting to 100 gpm is diverted through a ferment~ation branch having a 10,000 gallon fermentor vessel therein. The fermentor vessel is maintained at a temperature of 30C + 1 and a pH of from 7 to 9 is maintained by appropriate additions of H2SO4, HCl, C02, Na2CO3 or NaOH.
During a period in which sewage temperatures in the aeration tank fluctuated between 50F (10C) and 60F (15.5C), a contlnuous flow of 100 gpm i9 maintained from the fermentor vessel to the aeration tank.
Nltrlficatlon in the single aeration tank is effective to reduce NH3 concentratlons from lnltial levels of 25 to 40 mg/l NH3 in the aeration basin feed stream to less than l ppm NH3 in the tank overflow.
As described, thetemperature of the contents of the fermentor vessel must be maintained in the temperature range of from about 30 to about 35C. In most situations this will mean providing heatlng means to prevent the temperature of the vessel contents from dropping below the desired temperature range. However, ln some circumstances, as when the fermentor vessel 18 located in a heated building, or under peak growth condltions, the vessel contents may tend to exceed the necessary tempera-ture range and, ln that case, appropriate cooling means will be required.
Emphasis has been placed in this description on the use of a fermentation zone for growing nitrifying bacteria which can then be supplied to the aeration zone of a "single sludge" system in order to malntain an adequate nitrifying bacteria population in that zone. It is contemplated that the fermentation zone of the invention may also be used ln connectlon wlth the "two-sludge" system, ln whlch case, the nltrlfylng bacterla produced ls supplled to the vessel or vessels devoted to the nltrlflcatlon reaction. In this way, the effective operatlng i 30 sea~on of the "two-sludge" system can be extended in northern climates.
It will be noted that the relatively small fermentor vessel represents a substantial cost saving over the large second tank required in the two-sludge system, not only in terms of equipment cost, but in terms of land usage as well.
Although the present invention has been described with particu-lar reference to preferred embodiments, it will be apparent to those skilled in the art that variations and modifications may be made without departing from the Qssential spirit and scope of the invention. It is intended to include all such variations and modifications.
... . .. . . . . .
Claims (13)
1. In the process of aerobic digestion of sewage which includes subjecting a sewage feed containing carbonaceous and nitrogenous pollutants to aeration and thereafter to clarification, the improvement therein comprising the step of maintaining a predetermined population of nitrifying bacteria in the sewage undergoing aeration by introducing additional quantities of said bacteria as required so as to obtain a high degree of nitrification, said additional quantities of nitrifying bacteria being obtained by the steps of establishing a fermentation zone for said nitrifying bacteria, controlling the temperature of said fermentation zone, controlling the pH of said fermentation zone and furnishing nutrients and growth promoters to said fermentation zone to thereby establish optimum growth conditions for said nitrifying bacteria.
2. The process of claim 1 in which the aeration of said pollutants is carried out in a single treatment zone and the temperature in said fermentation zone is maintained in the temperature range of from about 30°C up to about 35°C.
3. The process of claim 2 in which the pH of said fermentation zone is maintained in the range of from 7 to 9.
4. The process of claim 3 in which the pH in the fermentation zone is adjusted by appropriate additions of one or more of CO2, H2SO4, HCl, NaOH and Na2CO3.
5. The process of claim 4 in which NH4+, Ca(OH)2 and HCO3-are introduced into the fermentation zone as growth promoters.
6. The process of claim 3 wherein the fermentation zone is agitated to mix the contents thereof.
7. The "single sludge" process of aerobic digestion of sewage for treatment of carbonaceous and nitrogenous pollutants comprising the steps of, a. aerating a primary effluent sewage feed in a single aeration zone, b. establishing and maintaining optimum growth conditions in a fermentation zone for nitrifying bacteria, including (1) supplying a fluid medium comprising a primary effluent sewage feed having nitrifying bac-teria therein to said fermentation zone, (2) controlling the temperature in said fermen-tation zone in a preferred temperature range, (3) controlling the pH of the growth medium in said fermentation zone to a value within a preferred range, c. supplying from said fermentation zone said fluid medium containing said nitrifying bacteria to said aeration zone to maintain an adequate population of nitri-fying bacteria in said aeration zone, and d. conducting the overflow liquid of said aeration zone to a clarification zone wherein a separation is effected to obtain a nitrate-containing liquid which is to be subjected to further treatment and a sludge for recycling to the aeration zone and for separate disposition.
8. The process of claim 7 wherein the temperature in the fermentation zone is from about 30°C up to about 35°C.
9. The process of claim 8 wherein the pH is maintained in the range from 7 to 9.
10. The process of claim 9 wherein the substances in said fermentation zone are agitated to provide thorough mixing.
11. An activated sludge sewage treating system including an aeration zone for the simultaneous metabolism of carbonaceous compounds and conversion of nitrogen compounds in the sewage to a nitrate form and a settling zone for separation of a nitrate-containing effluent from sludge produced in said aeration zone, a fermentation zone providing a favorable growth environment for the nitrifying bacteria genus Nitroso-monas and genus Nitrobacter with provision for supplying said nitrifying bacteria to said aeration zone so that an effective amount thereof is maintained in said aeration zone, the fermentation zone comprising:
a. a fermentor vessel for holding a fluid growth medium, b. first conduit means connecting a sewage inlet with said fermentor vessel for introducing a feed of sewage into said vessel, c. temperature control means for maintaining the vessel contents at a temperature in the range from about 30°C to about 35°C, d. agitating means for stirring said vessel contents, e. inlet means connected to said fermentor vessel for introducing additives into said vessel to maintain the pH of the vessel contents at a level in the range 7 to 9 and for supplying nutrients and growth promoters, and f. conduit means connecting said fermentor vessel with said aeration zone for withdrawing predetermined amounts of said growth medium containing nitrifying bacteria from said vessel and injecting said withdrawn bacteria-containing growth medium into said aeration zone.
a. a fermentor vessel for holding a fluid growth medium, b. first conduit means connecting a sewage inlet with said fermentor vessel for introducing a feed of sewage into said vessel, c. temperature control means for maintaining the vessel contents at a temperature in the range from about 30°C to about 35°C, d. agitating means for stirring said vessel contents, e. inlet means connected to said fermentor vessel for introducing additives into said vessel to maintain the pH of the vessel contents at a level in the range 7 to 9 and for supplying nutrients and growth promoters, and f. conduit means connecting said fermentor vessel with said aeration zone for withdrawing predetermined amounts of said growth medium containing nitrifying bacteria from said vessel and injecting said withdrawn bacteria-containing growth medium into said aeration zone.
12. The sewage treating system of claim 11 wherein the tempera-ture control means is a heating device.
13. A "single sludge" activated sludge system comprising an aeration tank having a sewage inlet conduit for treating a sewage feed to remove carbonaceous and nitrogenous pollutants and a clarifier for receiving overflow liquid from the aeration tank to separate sewage sludge from the liquid, a fermentation zone for developing a fluid medium rich in nitrifying bacteria and supplying said fluid medium with the nitrifying bacteria to said aeration tank, said fermentation zone com-prising a fermentor vessel, inlet conduit means connected to said fermentor vessel for supplying sewage feed, nutrients and growth promoters to said vessel, agitating means operative on the contents of said vessel, temperature control means for maintaining the vessel contents in a pre-determined temperature range, and outlet conduit means connecting said fermentor vessel with said aeration tank for supplying the fluid medium with the nitrifying bacteria therein to said aeration tank.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US45606674A | 1974-03-29 | 1974-03-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1043477A true CA1043477A (en) | 1978-11-28 |
Family
ID=23811288
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA218,823A Expired CA1043477A (en) | 1974-03-29 | 1975-01-28 | Method and apparatus for nitrification of sewage |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1043477A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110358707A (en) * | 2019-07-03 | 2019-10-22 | 东莞市顶盛环保科技有限公司 | One kind is for trade effluent except ammonia nitrogen bacteria agent and preparation method thereof |
| CN114149079A (en) * | 2021-12-28 | 2022-03-08 | 郑州轻工业大学 | Sludge fermentation enhanced short-cut denitrification-anaerobic ammonia oxidation denitrification and phosphorus recovery device and method |
-
1975
- 1975-01-28 CA CA218,823A patent/CA1043477A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110358707A (en) * | 2019-07-03 | 2019-10-22 | 东莞市顶盛环保科技有限公司 | One kind is for trade effluent except ammonia nitrogen bacteria agent and preparation method thereof |
| CN114149079A (en) * | 2021-12-28 | 2022-03-08 | 郑州轻工业大学 | Sludge fermentation enhanced short-cut denitrification-anaerobic ammonia oxidation denitrification and phosphorus recovery device and method |
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