JP2007275747A - Wastewater treatment method and wastewater treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wastewater treatment method which enables the suitable removal of ammonia contained in wastewater. <P>SOLUTION: The wastewater treatment method of carrying out wastewater treatment by nitryfying and denitrifying the wastewater containing ammonia with activated sludge comprises containing at least any one selected from the group consisting of ethanol, acetaldehyde and ethyl acetate, and loading the wastewater with the initial distillate of whisky which is produced in a whisky production process before a denitrification reaction is carried out by denitrification bacteria in the activated sludge. The method can obtain a denitrification efficiency similar to the case of methanol loaded by loading the initial distillate of the whisky as an electron donor and reduce the treatment cost of ammonia-containing wastewater. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wastewater treatment method and a wastewater treatment apparatus for wastewater treatment by nitrifying and denitrifying wastewater containing ammonia with activated sludge.

  Conventionally, there is a method of biologically treating wastewater containing ammonia using activated sludge. As such a wastewater treatment method, there is a nitrification process in which ammonia is oxidized to nitric acid by nitrifying bacteria in activated sludge and a denitrification process in which nitric acid is converted to nitrogen by denitrifying bacteria in activated sludge. is there.

In the nitrification process, ammonia-oxidizing bacteria, which are nitrifying bacteria, produce nitrous acid by using ammonia in wastewater as an electron donor under aerobic conditions, and proliferate therewith. Further, nitrite-oxidizing bacteria, which are nitrifying bacteria, produce nitric acid using nitrous acid as an electron donor under aerobic conditions, and grow together therewith.
On the other hand, in the denitrification step, denitrifying bacteria reduce nitric acid to molecular nitrogen using methanol as an electron donor under anaerobic conditions, and grow together therewith. Nitrogen produced by denitrifying bacteria is released to the atmosphere.

  Here, the reason why methanol is used as an electron donor in the denitrification step is that methanol has an advantage that it is inexpensive and easy to handle, whereas methanol is not suitable for the human body. It is harmful and includes the risk of blindness if consumed in large quantities. From such a viewpoint, it is conceivable to use a substance other than methanol as the electron donor.

  Conventionally, as a configuration using an electron donor other than methanol, for example, an organic acid such as acetic acid, an alcohol such as ethanol, or a saccharide such as glucose is known (for example, see Patent Documents 1 to 4). ). Moreover, what uses the waste liquid alcohol byproduced when manufacturing alcohol from molasses is also known (for example, refer patent document 5).

JP-A-11-90485 JP-A-6-126298 Japanese Patent No. 3214707 JP 2003-71490 A Japanese Patent Laid-Open No. 62-286596

  However, in the configurations described in Patent Documents 1 to 4, since the substance used as the electron donor is expensive, the amount of the electron donor to be used is large when wastewater treatment of a high concentration of ammonia is performed in large quantities. Therefore, there is a possibility that the wastewater treatment cost becomes very high.

On the other hand, since the configuration described in Patent Document 5 uses waste liquid alcohol as an electron donor, it is possible to reduce wastewater treatment costs.
However, the specific component constitution of the waste liquid alcohol is not shown, and it is unclear which component in the waste liquid alcohol functions effectively as an electron donor for denitrifying bacteria. In addition, the addition effect of the electron donor should be evaluated by the rate of nitrogen generation due to the action of denitrifying bacteria, but the effect of addition of the electron donor is evaluated by the rate of formation of nitric acid and nitrous acid by the action of nitrate bacteria. The actual effect of adding the waste liquid alcohol is unknown. Thus, since it is unclear how the waste alcohol should be administered in a practical situation, ammonia may not be reliably treated.
Moreover, even if the effect of adding an electron donor is evaluated based on the production rate of nitric acid and nitrous acid, the waste liquid alcohol has a denitrification rate less than half that of methanol (see Table 2). There is a risk that a large amount of liquid alcohol must be administered. For this reason, the component which does not function as an electron donor in the waste liquid alcohol will be present in a large amount in the wastewater, and there is a risk that the COD (Chemical Oxygen Demand) concentration in the treated water after the wastewater treatment will increase. .

  In view of the above problems, an object of the present invention is to provide a wastewater treatment method and a wastewater treatment apparatus that can suitably remove ammonia contained in wastewater.

The present invention has been devised on the basis of the knowledge that by using whiskey initial distillate as an electron donor for denitrifying bacteria, ammonia in waste water can be treated at low cost and with high efficiency. The gist of this is as follows.
In general, whiskey is accompanied by low boiling point alcohols other than ethanol, aldehydes and esters, so distillation is indispensable. The first fraction (whiskey first fraction) is the cause of headache and sickness. It is excluded because it becomes. This whiskey initial product containing a large amount of ethanol has not been effectively used, and is currently being processed as industrial waste or fuel.

  The wastewater treatment method of the present invention according to claim 1 is a wastewater treatment method for treating wastewater containing ammonia by nitrification and denitrification with activated sludge, and denitrifying reaction by denitrifying bacteria in the activated sludge Before the process is performed, whiskey primary distillate, which contains at least one of ethanol, acetaldehyde, and ethyl acetate and is a waste liquid generated in the whiskey production process, is added to the waste water. .

  Here, as the initial whiskey product, for example, in 1 L, ethanol 605.6 g, ethyl acetate 19.8 g, acetaldehyde 4.1 g, isoamyl alcohol 0.52 g, acetal 0.48 g, isobutanol 0.20 g, n- Propyl alcohol 0.12 g, isopropyl alcohol 0.04 g, and other water-containing ones can be used. In the present invention, the composition of the whiskey initial product is not limited to this, as long as it contains at least one of ethanol, acetaldehyde, and ethyl acetate, and the content of each component is also described above. It is not limited to what you did.

According to the present invention as described above, ammonia in waste water can be suitably removed.
In other words, since whiskey initial distillate that is cheaper than methanol is used as an electron donor, even if a large amount of electron donor is used to treat a large amount of wastewater containing high concentration of ammonia, the cost is kept low. be able to. In addition, whiskey first-distillate functions almost the same as methanol as an electron donor, resulting in denitrification efficiency equivalent to methanol, and higher denitrification efficiency than adding expensive ethanol alone. Can be obtained. Thus, wastewater treatment costs can be reduced without reducing the level of treatment efficiency of ammonia-containing wastewater.
In particular, ethanol and acetaldehyde in the initial whiskey product and ethanol and acetic acid produced by the decomposition of ethyl acetate in the initial whiskey product by sludge function effectively as an electron donor. Accordingly, the dose of the whole whiskey initial product can be adjusted. For this reason, since a suitable quantity of whiskey first-distillate can be administered in a practical use scene, the ammonia in waste water can be processed reliably.
Further, by adding the whiskey primary product as an electron donor, a denitrification efficiency almost as high as that of methanol can be obtained, so that the dose of the whiskey primary product is higher than the alcohol waste liquid described in Patent Document 5 above. Less is required, and it is possible to prevent the COD concentration in the treated water after the waste water treatment from being improved. Further, in the present situation where the whiskey initial product is processed as industrial waste or fuel, the whiskey initial product can be effectively used. Therefore, it can also contribute to environmental conservation.

The waste water treatment method of the present invention according to claim 2 is the waste water treatment method according to claim 1, wherein the amount of the whiskey initial distillate added is 600 ppm or more and 1500 ppm with respect to the inflow amount of the waste water per day. The adjustment is performed under the following conditions.
According to the present invention, by adding the whiskey initial fraction under the above conditions, the denitrification reaction proceeds well, and a denitrification effect comparable to that of methanol can be obtained. In addition, when the addition amount of the whiskey initial distillate is lower than 600 ppm or higher than 1500 ppm with respect to the inflow amount of the wastewater per day, a sufficient denitrification effect cannot be obtained.

The waste water treatment method of the present invention described in claim 3 is the waste water treatment method according to claim 1 or claim 2, wherein the concentration of COD component in the treated water after the waste water treatment is added to the whiskey initial product. The whiskey initial distillate is added under the condition of 50 ppm or less with respect to the concentration of the COD component in the treated water when the wastewater treatment is carried out under non-removing conditions.
More preferably, the whiskey initial distillate is added under the condition that the concentration of the COD component in the treated water does not exceed 30 ppm relative to the concentration of the COD component in the treated water under the condition where the whiskey initial distillate is not added.

  According to the present invention as described above, since the concentration of the COD component in the treated water becomes low enough to be within the environmental regulation range, the treated water can be discharged to the public water surface without any problem. In addition, when the concentration of the COD component in the treated water exceeds 50 ppm with respect to the concentration of the COD component in the treated water under the condition where the whiskey initial distillate is not added, the concentration of the COD component in the treated water is There is a risk of falling outside the environmental regulations.

A wastewater treatment method according to a fourth aspect of the present invention is the wastewater treatment method according to any one of the first to third aspects, wherein the ammonia concentration in the wastewater is 300 ppm or more.
More preferably, the ammonia concentration in the waste water is 500 ppm or more and 3000 ppm or less.
ADVANTAGE OF THE INVENTION According to this invention, optimal waste_water | drain processing can be implemented at low cost with respect to high concentration ammonia containing waste_water | drain whose ammonia concentration is 300 ppm or more, such as waste_water | drain from power generation equipment.

  The wastewater treatment method of the present invention according to claim 5 is the wastewater treatment method according to any one of claims 1 to 4, wherein the activated sludge after the denitrification reaction is performed by the denitrifying bacteria, It returns to the activated sludge before nitrification reaction is performed by the nitrifying bacteria in the activated sludge.

  Here, nitrifying bacteria and denitrifying bacteria are not used in independent tanks in wastewater treatment equipment, but move in the tank along the flow of wastewater being nitrified and denitrified sequentially, and used in a mixed state. Has been. At this time, each bacterium continues to be exposed to an inappropriate environment until it returns to an environment suitable for its own reaction and growth, during which nitrifying bacteria and denitrifying bacteria with relatively low growth ability are inactivated. There is a problem of end up.

In this respect, according to the present invention, the addition of the whiskey first-run product can improve the activity of nitrifying bacteria even in an anaerobic atmosphere tank in which the denitrification reaction proceeds, and can prevent inactivation. The sludge after the denitrification reaction is returned to the tank in an aerobic atmosphere where the nitrification reaction proceeds, so that nitrification bacteria and denitrification bacteria with relatively low growth ability can be replenished to the nitrification tank. -The efficiency of the denitrification reaction can be further increased.
In addition, by returning sludge after denitrification to the aerobic tank, unused whiskey initial contents, etc. contained in the sludge after denitrification can be consumed again by activated sludge. The COD concentration in the treated water can be reduced.

  The waste water treatment method of the present invention according to claim 6 is the waste water treatment method according to claim 5, wherein the waste water is waste water generated when desulfurizing and denitrating combustion exhaust gas in a power generation facility. To do.

Here, since the power generation facility is always operating, a large amount of combustion exhaust gas is continuously generated. This combustion exhaust gas is subjected to desulfurization / denitration treatment, but the waste water generated during the treatment contains high-concentration ammonia and cannot be directly discharged to the public water surface.
Here, a method of adding a chemical flocculant such as lime or iron chloride to the wastewater to precipitate and remove ammonia from the wastewater can be considered, but in order to treat a large amount of wastewater containing high concentration of ammonia. Requires a large amount of flocculant, which increases the processing cost. On the other hand, wastewater treatment using activated sludge nitrification / denitrification can be carried out at a low cost, but the wastewater contains almost no BOD (Biological Oxygen Demand) component that is a nutrient source for activated sludge. Bacteria that nitrify and denitrify wastewater are extremely inactivated. From such a point of view, there is a need for a technique for efficiently and efficiently treating a large amount of waste water from power generation facilities.

  In this regard, according to the present invention, even in the wastewater from the power generation facility with insufficient BOD concentration, by adding the whiskey initial distillate, the sludge after denitrification is returned to the sludge before the nitrification reaction, The activity of the sludge can be maintained and improved, and nutrition can be replenished to the sludge. Therefore, the nitrification / denitrification reaction can proceed well. As described above, the present invention can exhibit a particularly excellent effect in the treatment of wastewater from power generation facilities, and can remove high-concentration ammonia in the wastewater with high efficiency.

  The waste water treatment device of the present invention according to claim 7 is a waste water treatment device for waste water treatment by nitrifying and denitrifying waste water containing ammonia with activated sludge, and is provided so that the waste water can be introduced inside, A nitrification tank that nitrifies ammonia in the wastewater with nitrifying bacteria in the activated sludge filled inside, and a wastewater nitrified in the nitrification layer is introduced inside the nitrification layer. A denitrification tank for denitrifying nitric acid in the wastewater by denitrifying bacteria in the activated sludge filled inside, and connected to the denitrification tank, and in the wastewater in the denitrification tank, ethanol, acetaldehyde and ethyl acetate Injecting means for injecting whiskey initial fraction, which is a waste liquid generated in the whiskey production process, including at least one of them, provided downstream of the denitrification tank, and inside the denitrification tank A receiving tank in which denitrified wastewater is introduced and accommodates the wastewater, and a return means provided at the bottom of the receiving tank and returning activated sludge deposited on the bottom of the receiving tank to the nitrification tank. The waste water is characterized by being waste water generated when the combustion exhaust gas is desulfurized and denitrated in a power generation facility.

According to the present invention as described above, ammonia in the wastewater can be suitably removed by adding the whiskey initial distillate as an electron donor, as in the above-described wastewater treatment method of the present invention.
In particular, it is possible to suitably remove ammonia in the wastewater from the power generation facility having an insufficient BOD concentration and high temperature. That is, the activity of nitrifying bacteria and denitrifying bacteria can be improved by adding the whiskey first-run product to the denitrification tank wastewater and returning the sludge in the receiving tank to the nitrification tank, so the BOD concentration in the wastewater is insufficient. Even if it exists, the inactivation of the said microbial cell can be prevented. For this reason, in the nitrification / denitrification tank, the nitrification / denitrification reaction can proceed efficiently, and the ammonia in the wastewater can be suitably removed.
In addition, by returning unused whiskey initial contents contained in the sludge in the receiving tank back to the nitrification tank and consuming it in activated sludge, the COD concentration in the treated water after wastewater treatment can be reduced, and the treated water It can be safely discharged to public water.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing a wastewater treatment apparatus for carrying out a wastewater treatment method according to an embodiment of the present invention.

[Configuration of wastewater treatment equipment]
In FIG. 1, reference numeral 1 denotes a waste water treatment apparatus. This waste water treatment apparatus 1 performs waste water treatment for nitrifying and denitrifying ammonia contained in waste water using activated sludge. Such a waste water treatment apparatus 1 includes a raw water storage layer 2, four nitrification tanks 3A to 3D, four denitrification tanks 4A to 4D, an oxidation tank 5, and a precipitation tank 6 connected in series. I have.

  The raw water reservoir 2 stores wastewater (hereinafter referred to as raw water) generated when the combustion exhaust gas is desulfurized and denitrated in the power generation facility. The raw water contains a high concentration of ammonia of 300 ppm or more, preferably 500 ppm or more and 3000 ppm or less, and a specific substance such as calcium sulfate. The raw water contains almost no BOD component as a nutrient source other than ammonia and the substance, and the concentration of the BOD component is 3000 ppm or less.

  The nitrification tanks 3 </ b> A to 3 </ b> D are aerobic tanks provided in series on the downstream side of the raw water reservoir 2, and perform a nitrification step of nitrifying ammonia contained in the raw water from the raw water reservoir 2. In the nitrification tanks 3A to 3D, the raw water from the raw water reservoir 2 is introduced into the nitrification tank 3A, and the raw water introduced into the nitrification tank 3A is circulated in order to the nitrification tanks 3B to 3D.

Piping of the nitrification blower 7 is connected to the bottom of each of the nitrification tanks 3A to 3D, and air is blown from the nitrification blower 7 at a flow rate of, for example, 100 to 2000 ml / l · min (aeration). Thereby, the inside of the nitrification tanks 3A to 3D is uniformly stirred and an aerobic atmosphere is formed.
And the reactor 31 for making activated sludge adhere is each provided in nitrification tank 3A-3D. In the activated sludge adhering to the reactor 31, ammonia-oxidizing bacteria and nitrite-oxidizing bacteria, which are aerobic nitrifying bacteria, mainly function. The means for attaching the activated sludge is not limited to the one in which the reactor 31 is installed, but an immobilization carrier that accommodates the activated sludge inside may be introduced into the nitrification tanks 3A to 3D.

  Examples of ammonia oxidizing bacteria include Nitrosomonas europaea, and such ammonia oxidizing bacteria produce nitrous acid as follows using ammonia in raw water as an electron donor.

〔Chemical formula〕
NH ₄ + 1.5O ₂ → NO ₂ ⁻ + H ₂ O + 2H ⁺ (1)

  Examples of nitrite oxidizing bacteria include Nitrobacter winogradskyi, and such nitrite oxidizing bacteria generate nitric acid as described below using nitrite generated by ammonia oxidizing bacteria as an electron donor.

〔Chemical formula〕
NO ₂ ⁻ + 0.5O ₂ → NO ₃ ⁻ (2)

An injection means 8 is connected to the nitrification tank 3A, and a predetermined amount of potassium phosphate (KH ₂ PO ₄ , K ₂ HPO ₄ , K ₃ PO ₄ ) aqueous solution is injected into the nitrification tank 3A from the injection means 8. It has come to be. Thereby, it becomes possible to improve the activity of nitrifying bacteria and denitrifying bacteria in the sludge.

Further, a pH sensor 32 for measuring the pH of raw water in the tank is connected to the nitrification tank 3A. The nitrification tank 3A is connected to pH adjusting means 33 for introducing a sodium hydroxide aqueous solution or the like into the tank liquid and adjusting the pH of the raw water in the tank to a predetermined value. With such a pH sensor 32 and pH adjusting means 33, the pH in the nitrification tanks 3A to 3D is maintained at a predetermined value.
The nitrification tanks 3A to 3D are provided with temperature control means (not shown) for controlling the temperature of the nitrification tanks 3A to 3D to a predetermined value.

The denitrification tanks 4A to 4D are anaerobic tanks provided in series on the downstream side of the nitrification tank 3D, and perform a denitrification step of denitrifying nitric acid contained in the raw water from the nitrification tank 3D. In the denitrification tanks 4A to 4D, raw water from the nitrification tank 3D is introduced into the denitrification tank 4A, and the raw water introduced into the denitrification tank 4A is circulated in order to the denitrification tanks 4B to 4D.
The inside of such denitrification tanks 4A to 4D is an anaerobic atmosphere, and a stirring device 41 is provided at the bottom, and the inside of each tank is uniformly mixed by the stirring of the stirring device 41. ing.

In the activated sludge which distribute | circulates inside such a denitrification tank 4A-4D, the denitrification bacteria which are anaerobic microbial cells mainly function. Examples of such denitrifying bacteria include Paracoccus denitrificans, which are nitrate reducing bacteria.
An injection means 9 is connected to the denitrification tank 4A, and a predetermined amount of whiskey initial distillate as an electron donor is injected from the injection means 9 into the denitrification tank 4A. The whiskey initial distillate is a waste liquid generated in the production process of whiskey, and uses one containing at least one of ethanol, acetaldehyde, and ethyl acetate.
The nitrate-reducing bacteria consume the whiskey initial product from the injection means 9 as an electron donor, and generate molecular nitrogen from nitric acid as shown below. Nitrogen gas generated by the action of the nitrate-reducing bacteria is released to the atmosphere from above the denitrification tanks 4A to 4D.

〔Chemical formula〕
2NO ₃ ⁻ + 10H ⁺ → N ₂ + 4H ₂ O + 2OH ⁻ (3)

  Further, a pH sensor 42 for measuring the pH of the tank liquid is connected to the denitrification tank 4A. The denitrification tank 4A is connected to pH adjusting means 43 for introducing a hydrochloric acid aqueous solution or the like into the raw water in the tank and adjusting the pH of the raw water in the tank to a predetermined value. With such a pH sensor 42 and pH adjusting means 43, the pH in the denitrification tanks 4A to 4D is maintained at a predetermined value. Further, the denitrification tanks 4A to 4D are provided with temperature control means (not shown) for controlling the temperature of the denitrification tanks 4A to 4D to a predetermined value.

  The oxidation tank 5 is a series of aerobic tanks provided downstream from the denitrification tank 4D, such as plant extracts remaining in raw water (hereinafter referred to as treated water) after denitrification from the denitrification tank 4D. The COD component of is oxidized. The piping of the nitrification blower 7 is connected to the bottom of the oxidation tank 5 like the nitrification tanks 3A to 3D, and air is blown from the nitrification blower 7 at a flow rate of, for example, 100 to 2000 ml / l · min (aeration ). Thereby, the oxidation tank 5 becomes an aerobic atmosphere, and the COD component is efficiently removed from the treated water by the action of nitrifying bacteria.

  Sludge return means 51 is provided at the bottom of the oxidation tank 5, and the activated sludge inside the oxidation tank 5 is returned to the nitrification tank 3A and / or the denitrification tank 4A at a predetermined frequency. It has become. Thus, the concentration of activated sludge in each of the nitrification tanks 3A to 3D and the denitrification tanks 4A to 4D is maintained at a predetermined value.

The sedimentation tank 6 is provided on the downstream side of the oxidation tank 5 and precipitates activated sludge contained in the treated water from the oxidation tank 5. In the settling tank 6, the activated sludge in the treated water from the oxidation tank 5 is deposited at the bottom. On the other hand, the supernatant liquid in the treated water is appropriately post-treated and discharged to the public water surface.
Further, similarly to the sludge return means 51 in the oxidation tank 5, a sludge return means 61 is provided at the bottom of the precipitation tank 6, and the sludge return means 61 removes activated sludge that has settled at the bottom of the settling tank 6. Return to the nitrification tank 3A at a predetermined frequency.

[Wastewater treatment operation]
Next, the waste water treatment operation using the waste water treatment apparatus 1 will be described.
First, the raw water from the power generation facility is introduced into the raw water reservoir 2, and the raw water stored in the raw water reservoir 2 is introduced into the nitrification tank 3A. At the same time, a predetermined amount of potassium phosphate is injected from the injection means 8 into the nitrification tank 3A. Thereby, the activity of sludge improves, the nitrification efficiency by nitrifying bacteria can be improved, and the inactivation of anaerobic denitrifying bacteria can be suppressed.

  The raw water nitrified in the nitrification tanks 3A to 3D is introduced into the denitrification tank 4A and flows in order from the denitrification tank 4A to the denitrification tank 4D. At the same time, a predetermined amount of whiskey initial distillate is injected into the denitrification tank 4A from the injection means 9. As a result, the activated sludge in the denitrification tanks 4A to 4D becomes highly active, and the anaerobic denitrification bacteria can advance the denitrification reaction with high efficiency even if the BOD component in the raw water is at a low concentration. In particular, ethanol and acetaldehyde in the first whiskey distill function as methanol as an electron donor. In addition, ethyl acetate in the whiskey initial fraction is decomposed by sludge, thereby producing ethanol and acetic acid. Such ethanol and acetic acid also function as an electron donor almost equivalent to methanol. On the other hand, inactivation of aerobic nitrifying bacteria can be suppressed also in the denitrification tanks 4A to 4D in an anaerobic atmosphere.

Thereafter, the raw water denitrified in the denitrification tanks 4A to 4D becomes treated water, is introduced into the oxidation tank 5, and is again exposed to the aerobic atmosphere. Thereby, COD such as whiskey initial fraction remaining in the treated water is removed, and the treated water after the oxidation treatment is introduced into the settling tank 6.
The activated sludge in the oxidation tank 5 is returned at a predetermined frequency by the sludge return means 51 to at least one of the nitrification tank 3A and the denitrification tank 4A. As a result, nitrifying bacteria and denitrifying bacteria having relatively low growth ability are introduced into the nitrifying tank 3A or the denitrifying tank 4A with high activity. For this reason, the nitrification reaction can proceed with higher efficiency in the nitrification tanks 3A to 3D, and the denitrification reaction can proceed with higher efficiency in the denitrification tanks 4A to 4D.

In the sedimentation tank 6, the activated sludge in the treated water is deposited at the bottom of the sedimentation tank 6, and the sedimented sludge is returned to the nitrification tank 3 </ b> A at a predetermined frequency by the sludge return means 61. Thereby, nitrifying bacteria are introduced into the nitrification tank 3A with high activity, and the nitrification reaction can proceed with high efficiency in the nitrification tanks 3A to 3D.
On the other hand, the supernatant liquid in the sedimentation tank 6 is subjected to post-treatment such as filtration as necessary, and then discharged to public water surfaces such as the sea and rivers. Thus, the waste water treatment is finished.

Here, the addition amount of the whiskey initial product by the injection means 9 is preferably adjusted under the condition of 600 ppm or more and 1500 ppm or less with respect to the inflow amount of raw water per day. Thereby, a denitrification effect can be improved reliably. In addition, when there is too much addition amount of whiskey initial distillate, it will accumulate | store gradually in denitrification tanks 4A-4D, and it will not only reduce the activity of sludge, but will raise the COD density | concentration in treated water.
In addition, the amount of whiskey initial fraction injected by the injection means 9 is such that the concentration of the COD component in the treated water after the wastewater treatment is that of the COD component in the treated water when the wastewater treatment is carried out without adding the whiskey initial fraction. The concentration is preferably 50 ppm or less, more preferably 30 ppm or less. Thereby, the said treated water can be discharged to a public water surface without a problem.

[Modification of Embodiment]
In addition, this invention is not limited to the above-mentioned embodiment, The deformation | transformation in the range which can achieve the objective of this invention, improvement, etc. are included in this invention.
For example, in the said embodiment, although the structure which uses the high concentration ammonia containing waste water from power generation equipment as raw | natural water was illustrated, it is not restricted to this. That is, in the wastewater treatment method of the present invention, denitrification treatment can be performed even on low concentration ammonia-containing wastewater. In addition, denitrification treatment can also be performed on wastewater containing BOD components other than ammonia, such as food factory wastewater and chemical facility wastewater.

  In the said embodiment, although the waste water treatment equipment 1 was set as the structure provided with four nitrification tanks 3A-3D and the denitrification tanks 4A-4D provided in the downstream of this nitrification tank, it is not restricted to this. That is, for example, the waste water treatment apparatus may include a denitrification tank and a nitrification tank provided on the downstream side of the denitrification tank, and return sludge to the denitrification tank. Even in such a configuration, waste water treatment similar to that of the above embodiment can be performed, and particularly waste water containing a large amount of ammonia and nitric acid such as waste water from chemical facility waste water can be suitably treated. Moreover, the number of nitrification tanks and denitrification tanks is arbitrary.

  In the above embodiment, the inside of the denitrification tanks 4A to 4D is an anaerobic atmosphere. However, a pipe of a nitrogen gas supply means (not shown) is further connected to the inside of the denitrification tanks 4A to 4D, and this nitrogen gas supply means It is good also as a structure which blows in nitrogen gas in each tank. Thereby, since an anaerobic atmosphere can be formed quickly, an anaerobic atmosphere can be formed from the initial stage of operation, for example, and a denitrification reaction can be advanced with high efficiency.

  In the said embodiment, it was set as the structure which provides the sedimentation tank 6, However, Instead of the sedimentation tank 6, or the downstream of the sedimentation tank 6, the mud collector which centrifuges the said treated water and condenses activated sludge is provided. May be. According to such a structure, the supernatant liquid and activated sludge in treated water can be more reliably separated.

  In the above embodiment, the sludge return means 51 is provided in the oxidation tank 5 and the sludge return means 61 is provided in the settling tank 6. However, the present invention is not limited to this, and the sludge return means includes the oxidation tank 5 and the settling tank 6. It is good also as a structure provided only in any one of these. Even in such a configuration, nitrifying bacteria and denitrifying bacteria can be supplemented to the nitrifying tank 3A or the denitrifying tank 4A, the efficiency of the nitrification / denitrification reaction can be increased, and the COD concentration in the treated water can be reduced.

In the above embodiment, the whiskey initial distillate is added only to the denitrification tank 4A. However, the present invention is not limited to this, and it may be added to at least one of the denitrification tanks 4A to 4C. Thereby, the whiskey initial distillate can be uniformly distributed in the denitrification tanks 4A to 4D, and the denitrification efficiency can be improved.
Moreover, it is good also as a structure added to at least any one of the nitrification tanks 3A-3D not only in the denitrification tank 4A, but the whiskey initial distillate. Although the nitrification tanks 3A to 3D are in an aerobic atmosphere, if the dissolved oxygen concentration is 1.2 mg / L or less, the denitrification reaction by the denitrifying bacteria can proceed. Moreover, since the activity of nitrifying bacteria can be improved, the treatment efficiency of ammonia can be improved. In particular, if the initial whiskey product is added to the nitrification layer 3D, the activity of the denitrifying bacteria can be improved in the nitrifying layer 3D, and the highly active denitrifying bacteria can be introduced into the denitrification tanks 4A to 4D. . For this reason, the denitrification efficiency can be further improved.

Hereinafter, the present invention will be described more specifically with reference to examples.
(1) Method for measuring sludge nitrification activity 220 ml of sludge was added to a 240 ml wide-mouth bottle containing a magnet and placed in a constant temperature water bath so that the sludge temperature was set to 36 ° C. On the other hand, a hole was made in the center of the silicone stopper that matched the wide-mouth bottle, and a sensor for a dissolved oxygen meter with a temperature sensor was attached. Furthermore, an air supply tube reaching the bottom of the bottle and an exhaust tube opened to the atmosphere were attached to the bottom of the silicon stopper. 125 ppm of ammonium chloride was added while flowing air without completely bringing the silicon stopper into close contact, and the silicon stopper was kept in close contact with the aerated state.
Subsequently, after confirming that the amount of dissolved oxygen rose to 5 mg / l or more, the air supply was stopped, and the time when the dissolved oxygen decreased to 4.5 mg / l was defined as 0 minute. Thereafter, the amount of dissolved oxygen that decreases with time was read, and the nitrification activity was evaluated from the amount of decrease in the amount of dissolved oxygen.

(2) Sludge denitrification activity measurement method As with the above nitrification activity measurement method, add 220 ml of activated sludge to a 240 ml wide-mouth bottle containing a magnet and place it in a constant temperature water bath so that the sludge temperature is 36 ° C. Set. On the other hand, a hole was made in the center of the silicone stopper that matched the wide-mouth bottle, and a sensor for a dissolved oxygen meter with a temperature sensor was attached. Furthermore, an air supply tube reaching the bottom of the bottle and an exhaust tube opened to the atmosphere were attached to the bottom of the silicon stopper.
Nitrogen gas was allowed to flow through the air supply tube. After confirming that the dissolved oxygen has reached 0, add 10% sodium nitrate solution to 125 ppm, then add 10% by weight methanol to 125 ppm, and simultaneously stop nitrogen air supply and exhaust tube A manometer equipped with a 5 ml reservoir containing 5N sodium hydroxide was connected to the end of the tube. The amount of nitrogen gas generated over time was read as the amount of gas accumulated from the connection through the gas generated in this manometer, and this was defined as denitrification activity.

(3) Operation of wastewater treatment apparatus 1 Raw water was continuously passed through the wastewater treatment apparatus 1 (see FIG. 1) provided with the nitrification tanks 3A to 3D and the denitrification tanks 4A to 4D.
The main ingredients in the raw water are 400 ppm calcium ion, 14,000 ppm sulfate ion, 90 ppm sodium ion, 15 ppm potassium ion, 500 ppm magnesium ion, 30 ppm iron ion, 150 ppm chlorine ion, 2 ppm vanadium ion, 1 ppm nickel ion and 1.2 ppm phosphorus. there were. The ammonium ion was 980 ppm.

The operation of the waste water treatment apparatus 1 was carried out by changing the load factor by setting the value obtained by dividing the amount of sludge supplied per day by the total capacity of the four nitrification tanks 3A to 3D as a load factor (%).
The nitrification tanks 3A to 3D were aired for the purpose of stirring and supplying oxygen, and the dissolved oxygen amount was kept in the range of 3 to 5 mg / L.
The temperature of the sludge was controlled to 35.5 to 36 ° C., and the pH was controlled to 7.7 with sodium hydroxide. The sludge MLSS (mixed liquor suspended solids) ranged from 4600 to 4900 mg / L.

  When operated at a load rate of 5% or less, ammonia and nitrous acid were almost zero at the exit of the nitrification tank 3D due to the action of ammonia oxidizing bacteria and nitrite oxidizing bacteria, and the entire amount of ammonia was converted to nitric acid. On the other hand, nitric acid completely disappeared and was converted into nitrogen gas at the denitrification tank 4D exit. Sludge was collected from the wastewater treatment device 1 operating under such conditions, and the following experiment was performed.

(4) Sludge adjustment management First, sludge adjustment management was performed using an experimental apparatus as shown in FIG.
Specifically, as shown in FIG. 2, two 10L and 5L jar fermenters were prepared. Sludge is extracted from the nitrification tank 3A (see FIG. 1) that is operating at a load factor of 5% in the above (3), and charged into two 10-liter jar fermenters, 4.65 L each. did. Similarly, sludge was extracted from the denitrification tank 4A (see FIG. 1), and 1.5 L each was charged into two 5-liter jar fermenters, which were designated as denitrification tanks C and D, respectively.

The nitrification tanks A and B and the denitrification tanks C and D were connected in series, and all of them were immersed in the thermostatic tank E, and the sludge in each layer was adjusted to 36 ° C.
In the raw water reservoir F provided on the upstream side of the nitrification tank A, a liquid to be treated was prepared by adding 25 ppm of dipotassium phosphate to the raw water. This liquid to be treated was poured into the nitrification tank A at a load factor of 15% (930 ml per day). Nitrification tanks A and B were stirred at the bottom with a motor while maintaining a pH of 7.8 using a 1N aqueous sodium hydroxide solution, and at the same time, air was allowed to flow at 0.15 vvm.
In the denitrification tanks C and D, the effluent from the nitrification tank B was introduced into the denitrification tank C while the bottom part was stirred with a motor in the same manner as the nitrification tanks A and B. The denitrification tanks C and D were maintained in an anaerobic state by flowing 0.15 vvm nitrogen gas. At the same time, 12 g of methanol (electron donor) per day was continuously supplied to the denitrification tank C by a micro pump. The increase in pH due to consumption of nitric acid was adjusted to pH 7.8 with a 1N hydrochloric acid aqueous solution.
Furthermore, an oxidation tank G and a precipitation tank H were provided in order on the downstream side of the denitrification tank D. The sludge flowing out from the denitrification tank D to the oxidation tank G was returned to the nitrification tank A at a rate of 9 L per day. Further, in order to keep the sludge concentration constant, the supernatant liquid accumulated in the sedimentation tank H was discarded, and the precipitated sludge was returned to the nitrification tank A twice a day. In addition, the phosphorus density | concentrations in the sludge of nitrification tank A and B and denitrification tank C and D at the time of experiment start were 4600 mg / kg and 4900 mg / kg.

Sludge was sampled from these nitrification tank B and denitrification tank D, the nitrification activity of sludge was measured by the method (1) above, and the denitrification activity of sludge was measured by the method (2) above. As a result, the nitrification activity was 0.11 in terms of dissolved oxygen concentration after 4 minutes, and the denitrification activity was 1.1 ml of nitrogen generation after 15 minutes. Moreover, as a result of centrifuging the excess sludge of the denitrification tank D at 12000G and measuring the COD of the supernatant, it was 14 ppm.
Thus, it can be seen that when methanol is added as an electron donor, the nitrification reaction and the denitrification reaction can proceed well.

(5) Effect by addition of various electron donors Among the conditions shown in (4) above, the type of electron donor and the amount added were changed, and the experimental apparatus shown in FIG. 2 was operated.
As the electron donor, whiskey primary fraction, methanol, ethanol, acetaldehyde and acetic acid were used. As shown in Table 1, the amount of each electron donor added to the denitrification tank C per day was 9.8 g (Example 1) for the whiskey initial fraction, and 6,12,24 g (reference example 1-) for methanol. 1 to 1-3), 6,12,24,36 g (Reference Examples 1-4 to 1-7) for ethanol, 6 g (Reference Example 1-8) for acetaldehyde, and 6 g (Reference Example 1-9) for acetic acid did. Further, as Comparative Example 1, the same experiment was conducted when no electron donor was added. The composition of the whiskey initial product is shown in Table 2.

  After each electron donor was added, the nitrification activity of sludge in the nitrification tank B was measured by the method (1) above, and the denitrification activity of the sludge in the denitrification tank D was measured by the method (2) above. The results of each experiment are also shown in Table 1. The sludge concentration was 4400 mg / L as a result of measuring sludge accumulated in the oxidation tank G.

In Table 1, it can be seen that in Example 1, the amount of nitrogen generated was significantly increased as compared with Comparative Example 1, and the amount of dissolved oxygen was significantly decreased as compared with Comparative Example 1. The increase in the amount of nitrogen generated is thought to be due to the fact that the initial whiskey functioned well as an electron donor for denitrifying bacteria. In addition, the decrease in the amount of dissolved oxygen is further improved in the nitrification tanks A and B by improving the activity of nitrifying bacteria in the denitrification tanks C and D by the whiskey initial product and returning sludge from the oxidation tank G to the nitrification tank A. This is probably because the activity of nitrifying bacteria was improved.
Further, in Table 1, it can be seen that Example 1 has the same amount of nitrogen generation as that of Reference Example 1-1. From this, it is understood that the whiskey initial product functions to the same extent as methanol as an electron donor.
And in Table 1, Example 1 shows that the amount of nitrogen generation is comparable or more than Reference Examples 1-4 to 1-7. This shows that the whiskey initial product has a higher function as an electron donor than ethanol.

Further, when ethanol (Reference Examples 1-4 to 1-7) and acetaldehyde (Reference Example 1-8), which are contained in a large amount of whiskey initial products shown in Table 2, are examined, both of them are more nitrogen than Comparative Example 1. It can be seen that the amount generated is significantly increased and the amount of dissolved oxygen is significantly decreased. This shows that the active ingredients in the whiskey initial product as an electron donor are ethanol and acetaldehyde.
It can also be seen that the amount of nitrogen generated in the acetic acid (Reference Example 1-9) generated by the decomposition of ethyl acetate with sludge is significantly higher than that in Comparative Example 1. In particular, it can be seen that acetic acid (Reference Example 1-9) has the same amount of nitrogen as methanol (Reference Example 1-1) and has a high function as an electron donor. Thus, since acetic acid (and ethanol) produced by the decomposition of ethyl acetate also functions well as an electron donor, it can be said that ethyl acetate contained in the whiskey initial distillate is one of the active ingredients.

  Further, in Table 2, when Reference Examples 1-4 to 1-7 are seen, when the addition amount is 6 to 24 g (4 to 16 g with respect to 1 L of sludge), the addition amount is 36 g (to 1 L of sludge). Compared with the case of 24g), the nitrogen generation amount is increased. Particularly when the addition amount is 6 g (4 g with respect to 1 L of sludge), a sufficiently high nitrogen generation amount is obtained, and it can be seen that the denitrification efficiency can be improved by adding a small amount of ethanol. From this, it was found that a good denitrification effect can be obtained by adjusting the amount of whiskey initial distillate to be adjusted to 600 ppm or more and 1500 ppm or less with respect to the inflow amount of raw water per day.

(6) Effect of returning sludge Among the conditions shown in (4) above, ethanol was used instead of methanol as the electron donor, the load factor was 10%, and excess sludge from the oxidation tank G was nitrified. The experimental apparatus shown in FIG. 2 was operated under the same conditions except that it was led to the precipitation tank H without being returned to the tank A.

Six days after the operation, the nitrification activity of sludge in the nitrification tank B was measured by the method (1), and the denitrification activity of sludge in the denitrification tank D was measured by the method (2). And 200 ml of sludge was each extracted from the nitrification tank B, the denitrification tank D, and the oxidation tank G, and it centrifuged at 12000G, and measured the COD density | concentration of each supernatant liquid. These results are shown in Table 3 as Example 2-1.
In addition, when the sludge density | concentration settled in the bottom part of the nitrification tank B and the denitrification tank D was measured, respectively, sludge density | concentration was 3200 and 3100 mg / L, respectively.
Thereafter, the sludge accumulated in the oxidation tank G was returned to the nitrification tank A at a rate of 460 ml per day, and the apparatus was operated in the same manner. Six days after the operation, 200 ml of sludge was extracted from the oxidation tank G, centrifuged at 12000 G, and the COD concentration of the supernatant was measured. The results are shown in Table 3 as Example 2-2.

  In Table 3, it turned out that COD density | concentration of the supernatant liquid in the oxidation tank G can be reduced 43% by returning. This is probably because COD such as unused ethanol was consumed in the nitrification layers A and B by returning sludge to the nitrification layers A and B.

(7) COD concentration in treatment liquid when initial whiskey product is added In (6) above, all sludges in nitrification tanks A and B and denitrification tanks C and D are discarded after a series of experimental operations. Then, the inside of each tank is washed, and sludge is newly collected from the wastewater treatment apparatus 1 (see FIG. 1) that is operating in (3) above, and the experimental apparatus (see FIG. 2) is used in the same manner as in (4) above ) Was launched. Then, 17.6 g of the whiskey initial product shown in Table 2 was continuously supplied to the denitrification tank C to operate the experimental apparatus.

  Two days after the operation, the nitrification activity of sludge in the nitrification tank B was measured by the method (1) above, and the denitrification activity of sludge in the denitrification tank D was measured by the method (2) above. And 200 ml of sludge was each extracted from the nitrification tank B, the denitrification tank D, and the oxidation tank G, and it centrifuged at 12000G, and measured the COD density | concentration of each supernatant liquid. The results are shown in Table 4 as Example 3.

  From Table 4, it can be seen that the nitrification activity and the denitrification activity are good, and the COD concentration of the supernatant liquid (treatment liquid) in the oxidation tank G is at a level that does not cause a problem even if it is discharged to the public water surface. Thus, by adding the whiskey initial product as an electron donor, the nitrification / denitrification reaction can proceed well, and the COD concentration in the treatment liquid can be made sufficiently low. I understood.

(8) Verification of whiskey initial product addition effect in actual machine Waste water treatment apparatus provided with nitrification tanks 3A to 3D having a capacity of 1000 tons per tank and denitrification tanks 4A to 4D having a capacity of 750 tons per tank 1 (see FIG. 1), the raw water was continuously passed.
The main ingredients in the raw water are 400 ppm calcium ion, 14,000 ppm sulfate ion, 90 ppm sodium ion, 15 ppm potassium ion, 500 ppm magnesium ion, 30 ppm iron ion, 150 ppm chlorine ion, 2 ppm vanadium ion, 1 ppm nickel ion and 1.2 ppm phosphorus. there were. The ammonium ion was 980 ppm. In order to compensate for the shortage of phosphoric acid and potassium, 30 ppm of potassium phosphate was added to the nitrification tank 3A per raw water.

The operation of the waste water treatment apparatus 1 was carried out by changing the load factor by setting the value obtained by dividing the amount of sludge supplied per day by the total capacity of the four nitrification tanks 3A to 3D as a load factor (%).
The nitrification tanks 3A to 3D are supplied with air for the purpose of stirring and supplying oxygen, the dissolved oxygen amount in the nitrification tanks 3A to 3C is in the range of 3 to 5 mg / L, and the dissolved oxygen amount in the nitrification tank 3D is 1.2. It was kept in the range of ~ 0.8 mg / L.
The oxidation tank 5 having a capacity of 600 tons is provided in the subsequent stage of the denitrification tank 4D, and the precipitation tank 6 having a capacity of 1000 tons is provided in the subsequent stage, and 50% of the sludge flowing into the oxidation tank 5 is returned to the nitrification tank 3A. And drove.
The temperature of the sludge was controlled to 35.5 to 36 ° C., and the pH was controlled to 7.7 with sodium hydroxide. Sludge MLSS (Mixed liquor suspended solids) ranged from 4600 to 4900 mg / l. A 50% methanol solution as an electron donor was supplied to the denitrification tank 4A inlet at a rate of 11 tons / day.

  When operated at a load rate of 25% or less, ammonia and nitrous acid were almost zero at the outlet of the nitrification tank 3D due to the action of ammonia oxidizing bacteria and nitrite oxidizing bacteria, and the entire amount of ammonia was converted to nitric acid. On the other hand, nitric acid was 1 ppm or less at the denitrification tank 4C outlet, and nitric acid completely disappeared and converted to nitrogen gas at the denitrification tank 4D outlet.

In the wastewater treatment apparatus 1 operated under such conditions, the electron donor is changed from a methanol solution to a whiskey initial fraction having the composition shown in Table 2, and the whiskey initial fraction is added to the nitrification tank 3D at 1 ton / The denitrification tank 4A was continuously fed at a rate of 5 tons / day.
As a result, ammonia was almost zero at the nitrification tank 3D outlet, and nitric acid was completely lost at the denitrification tank 4D outlet. In addition, the COD concentration of the supernatant liquid in the precipitation tank 5 was 8 ppm. Moreover, the whiskey initial distillate was not detected in the supernatant liquid in the sedimentation tank 6, and the COD concentration of the supernatant liquid was 11 ppm.
In this way, it was confirmed that the whiskey initial product works as an electron donor substantially equivalent to methanol even in the actual machine.

It is the schematic diagram which showed the waste water treatment apparatus for enforcing the waste water treatment method which concerns on one Embodiment of this invention. It is the schematic diagram which showed the experimental apparatus in one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Waste water treatment apparatus 2 ... Raw water reservoir 3A-3D ... Nitrification tank 31 ... Reactor 32 ... pH sensor 33 ... pH adjustment means 4A-4D ... Denitrification tank 41 ... Stirrer 42 ... pH sensor 43 ... pH adjustment means 5 ... Oxidation Tank (receiving tank)
51 ... Sludge return means 6 ... Sedimentation tank (receiving tank)
61 ... Sludge return means 7 ... Nitrification blower 8 ... Injection means 9 ... Injection means

Claims (7)

A wastewater treatment method for wastewater treatment by nitrifying and denitrifying wastewater containing ammonia with activated sludge,
Before the denitrification reaction is carried out by the denitrifying bacteria in the activated sludge, the whiskey initial distillate containing at least one of ethanol, acetaldehyde and ethyl acetate and being a waste liquid generated in the whiskey production process, A wastewater treatment method characterized by being added to the wastewater. The waste water treatment method according to claim 1,
The amount of the whiskey initial distillate added is adjusted under the condition of 600 ppm to 1500 ppm with respect to the inflow of the wastewater per day. In the waste water treatment method according to claim 1 or 2,
Under the condition that the concentration of the COD component in the treated water after the wastewater treatment is 50 ppm or less with respect to the concentration of the COD component in the treated water when the wastewater treatment is performed under the condition that the whiskey initial distillate is not added. A method for treating waste water, comprising adding the whiskey initial product. In the waste water treatment method in any one of Claims 1 thru | or 3,
The ammonia concentration in the waste water is 300 ppm or more. In the waste water treatment method according to any one of claims 1 to 4,
The wastewater treatment method, wherein the activated sludge after the denitrification reaction is performed by the denitrifying bacteria is returned to the activated sludge before the nitrification reaction is performed by the nitrifying bacteria in the activated sludge. The waste water treatment method according to claim 5,
The waste water is a waste water generated when desulfurizing and denitrating combustion exhaust gas in a power generation facility. A wastewater treatment device for treating wastewater containing ammonia by nitrification and denitrification with activated sludge,
A nitrification tank that is provided so that the waste water can be introduced inside, and nitrifies the ammonia in the waste water with nitrifying bacteria in the activated sludge filled inside,
A denitrification tank provided downstream of the nitrification layer, into which effluent nitrified in the nitrification layer is introduced, and denitrifying bacteria in the activated sludge filled inside denitrify the nitric acid in the effluent. When,
Connected to this denitrification tank, the whiskey initial distillate, which contains at least one of ethanol, acetaldehyde, and ethyl acetate and is generated in the whiskey production process, is injected into the wastewater in the denitrification tank. Injection means;
A receiving tank that is provided on the downstream side of the denitrification tank and into which the wastewater denitrified in the denitrification tank is introduced, and the wastewater is accommodated therein;
Returning means provided at the bottom of the receiving tank and returning the activated sludge accumulated at the bottom of the receiving tank to the nitrification tank,
The waste water is a waste water treatment device generated when desulfurizing and denitrating combustion exhaust gas in a power generation facility.

Images