JP2765170B2 - Treatment of wastewater containing fungicides - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is an improvement in a biological treatment method for wastewater containing a large amount of a disinfectant, such as toilet wastewater discharged from an aircraft.

[Prior Art] As a method of treating wastewater containing a large amount of a bactericide, for example, human wastewater circulated and used in an aircraft, a biological treatment method and a chemical treatment method by a coagulation sedimentation method are known. I have.

By the way, since a large amount of bromine-based germicides are added to aircraft effluent from a sanitary point of view, when performing wastewater treatment by a biological treatment method, in the process, a large amount of germicides contained in the effluents inhibit organic matter. However, it has been confirmed that the removal of organic substances can be performed without any problem. This is considered to be because organic matter (BOD) degrading bacteria acclimated to the fungicide and gained resistance.

However, in the case of performing nitrification and denitrification in addition to organic matter removal by the biological treatment method, even if organic matter removal is sufficiently possible, the bactericide inhibits nitrifying bacteria, causing nitrification inhibition and becoming stable. There is a problem that nitrogen is not removed.

[Problems to be Solved by the Invention] The present invention has been made to solve the above problems, and nitrates wastewater containing a colored disinfectant such as a bromine-based disinfectant by a biological treatment method.・ In the denitrification process, in the previous stage or in the process, a large amount of disinfectant contained in the wastewater is removed by adsorption with activated carbon to improve nitrification inhibition and provide a means to enable stable nitrogen removal. It is intended to do so.

[Means for Solving the Problems] The present invention provides means for solving the above-mentioned problems. In the present invention, wastewater containing a large amount of a colored germicide is subjected to nitrification and denitrification by a biological treatment method. By measuring the absorbance of the wastewater at the absorbance maximum absorption wavelength specific to the bactericide with an absorptiometer, if the absorbance exceeds 1.5,
It is characterized in that the powdered activated carbon is added to the wastewater and the absorbance after the addition is in the range of 0.5 to 1.5, for example,
In performing nitrification and denitrification treatment of human sewage wastewater containing a large amount of disinfectant mainly composed of methylene blue containing bromine and containing bromine by biological treatment, the absorbance maximum absorption wavelength specific to the disinfectant is used. The absorbance of the wastewater at a certain wavelength 662 nm is measured, and when the absorbance exceeds 1.5, powdered activated carbon is added to the wastewater, and the absorbance after the addition is measured.
It may be in the range of 0.5 to 1.5.

The powdered activated carbon may be added in the form of slurry, and may be added at a stage prior to the nitrification / denitrification step or at the nitrification / denitrification step.

[Action] According to the present invention, in performing nitrification and denitrification treatment of wastewater containing a large amount of a fungicide, particularly a colored fungicide, by biological treatment, the absorbance of the wastewater at the absorbance maximum absorption wavelength specific to the fungicide is measured. If the absorbance exceeds 1.5, powdery activated carbon is added to the wastewater in order to remove nitrification inhibition due to excess bactericide, and the excess bactericide is adsorbed and removed by activated carbon to eliminate the nitrification inhibition factor. Can be. In order to eliminate nitrification inhibition, the absorbance after the addition of activated carbon is preferably in the range of 0.5 to 1.5.

Explaining the treatment of human wastewater from a long-flighted aircraft, aircraft wastewater contains, from a sanitary point of view, a large amount of a disinfectant mainly composed of methylene blue having a blue color and containing bromine. When the wastewater is subjected to nitrification and denitrification by a biological treatment method, the absorbance of the wastewater at a wavelength of 662 nm, which is the maximum absorbance wavelength specific to the bactericide, is measured. If activated carbon is added and the absorbance after the addition is within the range of 0.5 to 1.5, the excess bactericide which becomes a nitrification inhibiting factor is adsorbed and removed by activated carbon, and without causing nitrification inhibition, nitrification
A denitrification treatment can be performed.

[Examples] Explaining the case of aircraft drainage as an example, as a disinfectant, a disinfectant mainly composed of methylene blue containing a blue pigment and containing bromine is used.
Contains 2mg / about. With this Br concentration, both BOD degrading bacteria and digestive bacteria are acclimated in about one week.

However, the usage amount of the disinfectant in the aircraft drainage varies depending on the use manual of each aircraft company, and the difference between the minimum value and the maximum value of the disinfectant concentration can be calculated by about 100 times.

(1) Experimental example Therefore, the Br concentration was set to 5 times (10 mg) the normal value (2 mg /).
FIG. 2 shows an experimental example of an increase in NH ₄ ⁺ -N contained in the treated water in the case of (/).

According to this experimental example, when the Br concentration was set to 5 times (10 mg /) of the normal value (2 mg /) on the third day after the lapse of days, the NH ₄ ⁺ -N concentration of the treated water rapidly increased, and the nitrification inhibition was apparently suppressed. It turns out to cause.

In this case, 5 days after the addition (8 days after the addition), the previous NH was added.
_{Since the} concentration becomes ₄ ⁺ -N, it can be seen that nitrifying bacteria acclimate to a high concentration of a bactericide and obtain resistance.

However, when the Br concentration fluctuates, acclimation of nitrifying bacteria cannot be expected, and the NH ₄ ⁺ -N concentration of the treated water becomes a high value.

(2) Experimental Example Next, FIG. 3 shows an adverse effect of the germicide on the nitrification reaction as an experimental example.

As test conditions N-VOL: 0.1 kg / m ³ · day Substrate: (NH ₄ ) ₂ CO ₃ type sludge: disinfectant acclimated at normal concentration (Br: 2 mg /) Activated sludge acclimated to disinfectant under the above test conditions As a result of measuring the effect on the nitrification rate by the bactericide,
FIG. 3 shows the NH ₄ ⁺ -N and NOx ^-- N concentrations on the vertical axis and the elapsed time on the horizontal axis.

As is clear from FIG. 3, when the concentration of the fungicide (using the Br concentration as an index) becomes three times the normal value (2 mg /), the nitrification rate becomes 3/4, and when the concentration becomes five times, the nitrification rate becomes one. It was found that the rate was slowed down to / 2, and nitrification damage by fungicides occurred.

(3) Experimental example However, when powdered activated carbon is added to the wastewater in the nitrification / denitrification step or in the preceding stage, the disinfectant is well adsorbed by the activated carbon and the blue pigment is decolorized.

As an experimental example, the disinfectant is 5 times the normal value (10mg /)
When 200 mg / powder of activated carbon powder was added under the same test conditions as in FIG. 3 using the increased amount of aircraft wastewater, it was found that a treatment result close to the normal value was obtained as shown in FIG.

(4) Experimental Example The content of the colored fungicide in the wastewater can be known by measuring the absorbance of the wastewater at the absorbance maximum absorption wavelength specific to the fungicide.

As an example, FIG. 5 shows an absorbance wavelength scan of a bactericide mainly containing methylene blue containing a blue pigment and containing bromine. That is, there is a maximum absorption at a wavelength of 662 nm,
It can be seen that the amount of activated carbon can be controlled at this wavelength.

In the experimental example, when measuring the absorbance of the wastewater at a wavelength of 662 nm, nitrification inhibition occurs when the absorbance exceeds 1.5, if the absorbance is 0.5 to 1.5, preferably 1.0 or less,
It was confirmed that nitrification inhibition was eliminated.

[Example] FIG. 1 is a process chart showing the method of the present invention, wherein A is an example in which powdered activated carbon is added at a stage prior to the nitrification / denitrification step
B shows an example of addition in the nitrification / denitrification step, and C shows an example of addition in both the former stage of the nitrification / denitrification step and the nitrification / denitrification step.

First, the process shown in FIG. 1A will be described.
1 is a raw water adjustment tank, 2 is an activated carbon reaction tank, 3 is a nitrification / denitrification tank, 4 is a sedimentation separation tank, 5 is a powdered activated carbon slurry tank, 6
Reference numeral 7 denotes an absorptiometer, 7 denotes a sequencer, and wastewater containing a large amount of a colored sterilizing agent such as aircraft wastewater is sent from a raw water regulating tank 1 to a nitrification / denitrification tank 3 via an activated carbon reaction tank 2.

The powdered activated carbon a is mixed and stirred with water in the slurrying tank 5 to be slurried, and then sent to the activated carbon reaction tank 2 by the pump P as necessary. In the drawing, M indicates a motor, and B indicates a blower.

The absorptiometer 6 is, for example, at a wavelength of 662 nm via a measuring tube 6a.
The absorbance of the wastewater retained in the raw water adjusting tank 1 in the above is measured, while the absorbance of the wastewater in the activated carbon reaction tank 2 is measured via the measuring pipe 6b.

Then, the absorbance of the waste water staying in the raw water adjusting tank 1 is 1.
If it exceeds 5, the pump P is driven via the sequencer 7 and the powdered activated carbon a slurried in the slurrying tank 5 is sent to the activated carbon reaction tank 2 and the absorbance of the wastewater in the activated carbon reaction tank 2 is reduced to 0.5 to 0.5. It is controlled within the range of 1.5, preferably 1.0 or less.

As a result, the disinfectant in the wastewater flowing into the nitrification / denitrification tank 3 is adsorbed and removed by activated carbon to such an extent that nitrification is not inhibited, and the nitrification / denitrification reaction conditions can be kept good.

In the step shown in FIG. 1B, the activated carbon reaction tank 2 is omitted and the powdered activated carbon a slurried in the slurrying tank 5 is directly sent to the nitrification / denitrification tank 3, and the nitrification / denitrification is performed via the measuring pipe 6b. The absorbance of the wastewater in the denitrification tank 3 is measured, and the absorbance is kept in the range of 0.5 to 1.5, which is suitable when the amount of the disinfectant in the wastewater is relatively small although the amount is large. I have.

In the step shown in FIG. 1C, the absorptiometer 6 and the sequencer 7 are omitted, and the powdered activated carbon a slurried in the slurrying tank 5 is always added to the activated carbon reaction tank 2 and the nitrification / denitrification tank 3. And is suitable when the amount of germicide contained in the wastewater is known.

[Effects] According to the present invention, in performing nitrification / denitrification treatment of wastewater containing a large amount of a colored germicide by a biological treatment method, the absorbance of the effluent at the absorbance maximum absorption wavelength specific to the germicide is measured by an absorptiometer. If the absorbance exceeds 1.5, add powdered activated carbon to the wastewater and adjust the absorbance after the addition.
By setting it in the range of 0.5 to 1.5, nitrification inhibition can be eliminated.

In addition, by adding powdered activated carbon as a slurry, it can be added almost uniformly to wastewater, and the addition position can be appropriately selected depending on the content of the fungicide.

[Brief description of the drawings]

FIGS. 1A, 1B and 1C are explanatory views showing the steps of the method of the present invention, and FIGS. 2 to 5 are graphs showing experimental examples. 1: Raw water adjustment tank, 2: Activated carbon reaction tank 3: Nitrification / denitrification tank, 4: Sedimentation separation tank 5: Activated carbon powder slurry tank 6: Spectrophotometer, 7: Sequencer P: Pump, M: Motor, B: Blower

Claims (6)

(57) [Claims] When a wastewater containing a large amount of a colored fungicide is subjected to nitrification and denitrification by a biological treatment method, the absorbance of the wastewater at an absorption maximum wavelength unique to the fungicide is measured by an absorptiometer. The method for treating wastewater, wherein powdered activated carbon is added to the wastewater when the value exceeds 1.5. 2. A wastewater containing a large amount of a colored germicide is subjected to nitrification and denitrification by a biological treatment method, and the absorbance of the effluent at the maximum absorption wavelength specific to the germicide is measured by an absorptiometer. If the value exceeds 1.5, add powdered activated carbon to the wastewater and adjust the absorbance after addition to 0.5 to 1.5.
A method for treating wastewater, characterized by being within the range of. 3. Nitrogen and denitrification treatment of an aircraft wastewater containing a large amount of a disinfectant mainly composed of methylene blue containing bromine and containing bromine by a biological treatment method. Measure the absorbance of the wastewater at 662 nm, which is the maximum absorbance wavelength of the agent, and if the absorbance exceeds 1.5, add powdered activated carbon to the wastewater and keep the absorbance after addition within the range of 0.5 to 1.5. A method for treating wastewater, characterized in that: 4. The method for treating wastewater according to claim 1, wherein the activated carbon powder is added as a slurry. 5. The method for treating wastewater according to claim 1, wherein the activated carbon is added before the nitrification / denitrification step. 6. The method for treating wastewater according to claim 1, wherein the activated carbon is added in the nitrification / denitrification step.