JP2005021864A - Method and apparatus for treating water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a bactericidal effect when the microbe-containing water to be treated is treated. <P>SOLUTION: The water 3 to be treated is filtered by a filter medium 7 capable of collecting at least a microbe. The pH of a microbe surrounding environment on the medium 7 is controlled to be alkaline or acid. The microbe surrounding environment is heated, particularly, to ≥+40°C and ≤+100°C. The pH of the microbe surrounding environment is controlled to be 10-13. The water 3 in which the medium 7 is immersed is aerated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a water treatment method and a water treatment apparatus for sterilizing water (treated water) such as factory effluent.

  Conventionally, for example, in food factories, processing for washing beverage containers with washing water has been performed. A lot of spore bacteria (microorganisms) are attached to the beverage container, and the washing water is contaminated by the spore bacteria. Therefore, conventionally, a method has been adopted in which washing water is made alkaline and sterilized by heating to an appropriate temperature. However, spore bacteria have high heat resistance and have a limited sterilizing effect.

On the other hand, as a method of removing microorganisms such as bacteria, molds, and protozoa contained in the seed treated water, a filter medium capable of collecting microorganisms is disposed in the flow channel, and the microorganisms are fixed to the filter medium. There is also a method of purifying by this (see Patent Document 1).
JP-A-8-290159

  Then, when processing the to-be-processed water containing microorganisms, it aims at improving the sterilization effect.

  In the water treatment method of the first aspect of the invention, the water to be treated is filtered at least with a filter medium capable of collecting microorganisms, and the pH of the surrounding environment of the microorganisms on the filter medium is adjusted to be alkaline or acidic. It is something to process.

  The water treatment method of the invention of claim 2 is characterized in that the ambient environment of the microorganisms on the filter medium is adjusted to pH 10 to pH 13 in the above.

  The water treatment method of the invention of claim 3 is characterized in that in each of the above inventions, the surrounding environment of microorganisms on the filter medium is heated.

  The water treatment method of the invention of claim 4 is characterized in that the ambient environment of microorganisms on the filter medium is heated to + 40 ° C. or higher and + 100 ° C. or lower.

  The water treatment method of the invention of claim 5 is characterized in that in each of the above inventions, the pH is adjusted by electrolysis.

  A water treatment method according to a sixth aspect of the invention is characterized in that the water to be treated in which the filter medium is immersed in the above inventions is aerated.

  The water treatment method of the invention of claim 7 is characterized in that, in each of the above inventions, the filter medium is constituted by an immersion type flat membrane.

  The water treatment device of the invention of claim 8 includes a filter medium capable of collecting at least microorganisms in the water to be treated, and adjusts the pH of the surrounding environment of the microorganisms on the filter medium to be alkaline or acidic.

  The water treatment device of the invention of claim 9 is characterized in that the ambient environment of the microorganisms on the filter medium is adjusted to pH 10 to pH 13 in the above.

  A water treatment device according to a tenth aspect of the present invention is characterized in that in each of the above-mentioned inventions, the surrounding environment of microorganisms on the filter medium is heated.

  The water treatment device of the invention of claim 11 is characterized in that the ambient environment of the microorganisms on the filter medium is heated to + 40 ° C. or higher and + 100 ° C. or lower.

  A water treatment apparatus according to a twelfth aspect of the present invention is characterized in that in each of the above-mentioned inventions, an electrolysis means for adjusting pH is provided.

  A water treatment device according to a thirteenth aspect of the present invention is characterized in that in each of the above inventions, the water treatment device includes aeration means for aeration of the water to be treated in which the filter medium is immersed.

  The water treatment apparatus according to the invention of claim 14 is characterized in that, in each of the above inventions, the filter medium is constituted by a submerged flat membrane.

  A water treatment apparatus according to a fifteenth aspect of the present invention is characterized in that in each of the above-mentioned inventions, a pipe through which water to be treated flows is provided, and the pipe is made of an alkali-resistant or acid-resistant material.

  According to the present invention, the water to be treated is filtered with at least a filter medium capable of collecting microorganisms, and the pH of the surrounding environment of the microorganisms on the filter medium is adjusted to be alkaline or acidic. Microorganisms can be collected and the collected microorganisms can be killed in an alkaline or acidic environment. Thereby, disinfection ability, such as highly heat-resistant spore bacteria, can be improved.

  In particular, by heating the surrounding environment of the microorganism on the filter medium to + 40 ° C. or higher and + 100 ° C. or lower, it is possible to promote weakening of the microorganism and further improve the sterilization ability. Further, if the pH of the water to be treated is adjusted by electrolysis, it is not necessary to supply a chemical. Furthermore, clogging of the filter medium can be eliminated by aeration of the water to be treated in which the filter medium is immersed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a configuration of a water treatment apparatus 1 for carrying out the present invention. The water treatment apparatus 1 according to the embodiment performs sterilization treatment of washing water (hereinafter referred to as water to be treated) for washing a beverage container (a return container) in a food factory. It is a water tank which stores to-be-processed water (washing water) 3 which wash | cleans. A beverage container (not shown) is washed with water to be treated (wash water) in the water tank 2.

  In the figure, reference numeral 4 denotes an electric heater (seeds heater) as a heating device, which heats the water to be treated in the water tank 2. In the figure, reference numeral 6 denotes a treatment tank. A filter medium 7 is disposed in the treatment tank 6, and an aeration nozzle 8 as an aeration means is disposed below the filter medium. An electric heater (seeds heater) 15 as a heating device is also provided in the processing tank 6. As will be described later, the water to be treated 3 in the water tank 2 is circulated and supplied into the treatment tank 6, and the filter medium 7 and the aeration nozzle 8 are immersed in the water to be treated 3.

  FIG. 2 shows an enlarged view of the treatment tank 6 portion, and FIG. 3 shows a cross-sectional view of the filter medium 7. The filter medium 7 includes a pair of mesh-like filter membranes 11 and 11 that can collect at least microorganisms such as a submerged flat membrane, and a frame member 12 that fixes the filter membranes 11 and 11 at a predetermined interval. Has been. Reference numeral 13 denotes an outlet pipe for leading the treated water 3 between the filtration membranes 11 and 11 to the outside from the upper part of the frame member 12, and reference numeral 14 forcibly feeds the treated water 3 to the outside through the outlet pipe 13. A drainage pump (conveying means) 16 for drawing out.

  The frame member 12 is configured by a rectangular body having openings on the front surface and the rear surface, and the upper and lower ends and the left and right side ends are integrally configured. And the filtration membranes 11 and 11 are being fixed to the opening formed in this front surface and back surface, respectively with a predetermined space | interval. Thereby, the filtration membranes 11 and 11 will be comprised integrally with the frame member 12, and it will become possible to throw in the to-be-processed water 3 used as a process target easily. As will be described later, the filter media 7 are actually put into the processing tank 6 and the outlet pipe 13 is connected to the filter media 7.

  An insertion hole for connecting the outlet pipe 13 as described above is formed on the upper surface of the frame member 12, and the treated water 3 between the two filtration membranes 11 and 11 is drawn to the outside through the insertion hole. The lead-out piping 13 is inserted.

  Returning to FIG. 1, reference numeral 14 denotes a pump. The pump 14 is operated to pump up the water to be treated 3 in the water tank 2 through the water intake pipe 16 and convey it to the treatment tank 6 through the water discharge pipe 17. The outlet pipe 13 is connected to a pump 19 via a valve 18. The pump 19 is operated to suck up the water to be treated 3 between the two filtration membranes 11, 11 through the outlet pipe 13, and transport it to the water tank 2 through the water discharge pipe 22 through the valve 21.

  Reference numeral 23 denotes a tank for storing the water to be treated 3 for backwashing the filter material 7. The tank 23 is disposed above the filter material 7, and an outflow pipe 28 connected to the lower portion has a valve 24. And is connected to the outlet pipe 13 on the filter medium 7 side of the valve 18. Further, the water discharge pipe 22 branches, and this branch pipe 26 opens into the tank 23 via a valve 27 (note that the valves 18 and 24 are not shown in FIG. 2).

  A blower fan 31 is connected to the aeration nozzle 8 via a filter 32. The blower fan 31 is operated to suck air, and is discharged from the aeration nozzle 8 into the treatment tank 6 to aerate the water to be treated in the treatment tank 6 in which the filter medium 7 is immersed. Reference numeral 33 in FIG. 2 denotes a control device (control means), and the control device 33 controls the pumps 14 and 19, the electric heater 4, the valves 18, 21, 24 and 27 and the blower fan 31.

  The pipes 13, 16, 17, 22, 26, and 28 are made of an alkali- and acid-resistant material such as high-density polyethylene (PE), polystyrene, or fluororesin. Thereby, even if pH of the to-be-processed water 3 is made into the alkalinity or acidity mentioned later, damage, such as corrosion, does not arise in each piping. In addition, a temperature sensor that detects the temperature of the water to be treated 3 in the water tank 2 and a pressure sensor (indicated by PT in the figure) that detects the pressure in each pipe are connected to the control device 33.

Next, the sterilization processing operation of the water to be treated 3 by the water treatment apparatus 1 will be described. The treated water 3 includes spore bacteria as an example of microorganisms.
(1) Disinfection treatment At the start of this disinfection treatment, sodium hydroxide (NaOH) is introduced into the treated water 3 to make the treated water alkaline sterilized standard water. In the embodiment, NaOH and polyacrylic acid are added to the water 3 to be treated, and the pH is adjusted to 11.5.

  The control device 33 opens the valves 18 and 21 and closes the valves 24 and 27. And while operating the pump 14 and conveying the to-be-processed water 3 in the water tank 2 to the processing tank 6, the pump 19 is operated and the to-be-processed water 3 between the filter membranes 11 and 11 of the filter medium 7 is derived | led-out piping 13 Suck it up. Thereby, the to-be-processed water 3 in the processing tank 6 passes through the filtration membranes 11 and 11 from the outside and flows into the filtration membranes 11 and 11. At that time, spores (microorganisms) contained in the water to be treated 3 are captured and collected on the outer surfaces of the filtration membranes 11 and 11.

  When passing through the filtration membranes 11, 11, spore bacteria contained therein are collected and separated on the filtration membranes 11, 11 of the filter medium 7. At this time, since the pH of the water to be treated 3 is adjusted to 11.5 as described above, the pH of the surrounding environment of the spore bacteria collected on the filtration membranes 11 and 11 is 11.5 alkaline. Then, the water to be treated 3 sucked into the outlet pipe 13 is returned from the water discharge pipe 22 into the water tank 3 by the pump 19. Thereby, the spore bacteria in the to-be-processed water 3 in the water tank 2 are removed.

  The control device 33 controls the energization of the electric heaters 4 and 15 to heat and adjust the water to be treated 3 in the water tank 2 and the treatment tank 6. Further, the blower fan 31 is operated to discharge air (bubbles) from the aeration nozzle 8 to aerate the treated water 3 in the treatment tank 6 in which the filter medium 7 is immersed (0.3 L / min). Thereby, clogging of the filtration membranes 11 and 11 is eliminated.

  Here, the processing capability of the filtration membrane 11 is first verified. FIG. 4 shows changes in the processing flow rate of one filtration membrane 11. The horizontal axis in FIG. 4 indicates time, and the vertical axis indicates the daily processing amount (Flux) per unit membrane area. Although the initial treatment flow rate was about 0.6 L / min, it gradually clogged and dropped to about 0.05 L / min after 65 hours. After that, it changed substantially at a constant processing amount of about 0.04 L / min.

  Therefore, in the embodiment, as described above, the flow rate of the water to be treated 3 passed through the filtration membranes 11 and 11 by the pump 19 is set to 0.02 L / min. FIG. 5 shows the number of spore bacteria in the water to be treated 3 after being filtered by the filter membrane 11. The horizontal axis in FIG. 5 is time, and the vertical axis is the number of bacteria per mL. As is apparent from this figure, it can be seen that almost all of the spore bacteria can be removed by filtration of the filtration membrane 11.

  Next, the number of spore bacteria in the treated water (CFU) when the spore bacteria are added to the treated water (washing water) adjusted to pH 11.5 by adding an alkaline agent such as NaOH and heated to + 50 ° C. FIG. 6 shows the change in the results of experiments. The horizontal axis of FIG. 6 is time, and the vertical axis is the number of bacteria per mL.

  As is apparent from this figure, 99.9% of the spore bacteria could be killed in about 1 week in this situation. This is because spore bacteria do not die in a short period of time, but naturally die when placed in an environment of + 50 ° C. and pH 11.5 at all times. Therefore, the control device 33 controls the energization of the electric heaters 4 and 15 and sets the temperature of the water to be treated 3 to be adjusted to + 50 ° C. by heating. Thereby, the surrounding environment of the spore bacteria in the to-be-processed water 3 in the water tank 3 and the spore bacteria collected on the filtration membranes 11 and 11 of the process tank 6 will also be heated to +50 degreeC, and they are smoothly It will die out.

  Next, the processing capability of the water treatment device 1 determined by the number of filter media 7 will be verified. FIG. 7 shows the measurement result of the change in the number of spore bacteria in the water tank 2 in which, for example, a beverage container is washed in this kind of food factory. In the figure, the horizontal axis represents time, and the vertical axis represents the number of bacteria per mL. Black points indicate changes in winter and white points in summer. As can be seen from this figure, there is almost no change in the number of bacteria in the winter, but it increases at an average of 40 CFU / mL / hr in the summer. Therefore, the number of filter media 7 necessary for suppressing the increase in the number of bacteria in summer will be verified.

Now, the capacity of the aquarium 2 is 700 mL, the concentration of spore bacteria in the aquarium 2 at the elapsed time is R (CFU / mL), the initial concentration of spore bacteria in the aquarium 2 is R0 (CFU / mL), and is brought from the beverage container When the amount of spore bacteria is A (CFU / mL / hr) and the amount treated by the filter medium 7 is B (L / hr),
ΔR = AΔt−B / 700 · RΔt (1)
It can be said. Here, if C1 = A and C2 = B / 700,
dR / dt = C1-C2R [2]
It becomes. When this is integrated,
∫ [1 / (C1-C2R)] dR = ∫dt [3]
If this expression is expanded,
-1 / C1 [ln (C1-C2R) -ln (C1-C2R0)] = t
R = 1 / C2 [C1- (C1-C2R0) exp (-C2t)]
... [4]
It becomes. Calculation is performed by substituting the actual measurement value into Equation (4). Here, R0 uses summer data 120 (CFU / mL), and A uses summer data 40 (CFU / mL / hr). B designates the filtration membrane 11 [effective membrane area 0.84 square meters, 10.08 L / hr (calculated from the treatment flow rate 0.02 L / min per filtration membrane 11 (effective membrane area 0.1 square meters))] This is the amount of water (L) that can be treated when used. The calculation results are shown in FIG. In this figure, the horizontal axis represents time, and the vertical axis represents the number of bacteria per mL. Each point indicates a change in the number of bacteria for each number (0 to 400) of the filter media 7.

  From this result, it can be seen that the number of spore bacteria in the aquarium 2 can be kept low by using 100 or more filter media indicated by x points in FIG. Therefore, 100 filter media 7 are arranged in parallel in the treatment tank 6 and connected to the outlet piping 13 for use.

  As described above, in the present invention, the water to be treated 3 is filtered by the filter medium 7 and the spore in the water to be treated 3 is filtered by the filter medium 7 by making the pH of the surrounding environment of the spore bacteria on the filter medium 7 alkaline. Fungi can be collected and the collected spores can be killed in an alkaline environment. Thereby, it becomes possible to improve the sterilization ability of spore bacteria having high heat resistance, and even when the water to be treated is discarded, high concentration spore bacteria are not discharged to the external environment. In particular, by heating the water 3 to be treated, weakening of the spore bacteria can be promoted and the sterilization ability can be further improved. Moreover, since the to-be-processed water 3 in which the filter medium 7 was immersed is aerated, the clogging of the filter medium 7 can be eliminated.

Next, the reverse cleaning process of the water treatment apparatus 1 will be described.
(2) Backwashing treatment As spore bacteria accumulate on the outer surface of the filter membrane 11 of the filter medium 7 by such sterilization treatment, clogging proceeds. Therefore, the filter medium 7 is regularly backwashed. In that case, the control device 33 stops the pump 14, closes the valves 21 and 24, opens the valves 18 and 27 and operates the pump 19, thereby pumping up the treated water 3 into the tank 23 and storing it. Next, the pump 19 is stopped, the valve 18 is closed, the valve 24 is opened, and the water 3 to be treated is allowed to flow back from the tank 23 through the outflow pipe 28 and the outlet pipe 13 between the filter membranes 11 and 11 of the filter medium 7. .

  Thereby, since the to-be-processed water 3 distribute | circulates from the inner surface of the filtration membranes 11 and 11 toward an outer surface, the spore microbe adhering to the outer surface of the filtration membrane 11 can be removed, and it disinfects afterwards. It is possible to improve the processing efficiency.

  In addition, although the to-be-processed water was adjusted to pH11.5 in the Example, the alkalinity of the range of pH10 thru | or pH13 is suitable. Further, adjusting the water to be treated 3 to an alkaline environment having a pH of 8 or more or an acidic environment having a pH of 6 or less and removing the pH of the water to be treated 3 from the optimum pH of the spore bacteria (microorganisms) can also have an effect of removing spore bacteria. Furthermore, in the examples, the water to be treated was heated to + 50 ° C., but the effect of removing spore bacteria can be expected by adjusting the temperature within the range of + 40 ° C. to + 100 ° C.

  Moreover, although the surrounding environment pH of the spore bacteria collected by the filter medium 7 was adjusted by adjusting pH of the to-be-processed water 3 in an Example, it does not restrict, but pH of to-be-processed water 3 is not adjusted. The circulation of the water to be treated in the water treatment apparatus 1 is stopped at regular intervals, and for example, only the pH of the water to be treated in the treatment tank 6 is adjusted to adjust the ambient pH of the spore bacteria on the filter medium 7. It may be.

  Furthermore, in the embodiment, the pH of the water to be treated was adjusted by adding sodium hydroxide. As shown by the broken line in FIG. 2, for example, the water to be treated 3 in the treatment tank 6 comprises an anode 61 and a cathode 62. The pH of the water to be treated 3 may be adjusted by immersing an electrolytic means and performing electrolysis using these electrodes. In that case, the control device 33 controls the current applied to the anode 61 and the cathode 62 based on the pH of the water 3 to be treated, so that the pH of the water 3 to be treated around the filtration membranes 11 and 11 is alkaline or acidic as described above. Shall be adjusted automatically. If such an electrolysis means is used, the introduction of the above-mentioned chemical becomes unnecessary.

  Furthermore, in the examples, spore bacteria in washing water for washing beverage containers in food factories are targeted for treatment. However, the present invention is not limited to this, and the present invention is effective for treating various germs and microorganisms.

It is a block diagram of the water treatment apparatus for implementing this invention. It is an enlarged view of the processing tank part of the water treatment apparatus of FIG. It is sectional drawing of the filter medium of the water treatment apparatus of FIG. It is a figure which shows the change of the process flow rate of one filtration membrane. It is a figure which shows the number of spore bacteria in to-be-processed water after filtering with a filter membrane. It is a figure which shows the change of the number of spore microbes in a to-be-processed water at the time of adjusting to-be-processed water to pH11.5 and heat-adjusting to +50 degreeC. It is a figure which shows the measurement result of the change of the number of spore bacteria in the water tank which wash | cleans the drink container of this seed food factory. It is a figure which shows the number change of the microbe in to-be-processed water for every number of sheets of filter media.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water treatment apparatus 2 Water tank 3 Water to be treated 4, 15 Electric heater 6 Treatment tank 7 Filter material 8 Aeration nozzle 13 Outlet piping 14, 19 Pump 33 Controller 61 Anode 62 Cathode

Claims (15)

  A water treatment method characterized by treating the water to be treated with at least a filter medium capable of collecting microorganisms and adjusting the pH of the environment surrounding the microorganisms on the filter medium to be alkaline or acidic.   The water treatment method according to claim 1, wherein the ambient environment of microorganisms on the filter medium is adjusted to pH 10 to pH 13.   The water treatment method according to claim 1 or 2, wherein the surrounding environment of microorganisms on the filter medium is heated.   The water treatment method according to claim 3, wherein the surrounding environment of the microorganisms on the filter medium is heated to + 40 ° C or higher and + 100 ° C or lower.   The water treatment method according to claim 1, 2, 3, or 4, wherein the pH is adjusted by electrolysis.   The water treatment method according to claim 1, 2, 3, 4, or 5, wherein the water to be treated in which the filter medium is immersed is aerated.   The water treatment method according to claim 1, claim 2, claim 3, claim 4, claim 5, or claim 6, wherein the filter medium is composed of a submerged flat membrane.   A water treatment apparatus comprising a filter medium capable of collecting at least microorganisms in water to be treated, and adjusting the pH of the environment surrounding the microorganisms on the filter medium to be alkaline or acidic.   The water treatment apparatus according to claim 8, wherein the ambient environment of microorganisms on the filter medium is adjusted to pH 10 to pH 13.   The water treatment apparatus according to claim 8 or 9, wherein the surrounding environment of microorganisms on the filter medium is heated.   The water treatment apparatus according to claim 10, wherein the surrounding environment of the microorganisms on the filter medium is heated to + 40 ° C or higher and + 100 ° C or lower.   The water treatment apparatus according to claim 8, 9, 10, or 11, further comprising an electrolysis unit for adjusting the pH.   The water treatment device according to claim 8, 9, 10, 11, or 12, further comprising aeration means for aeration of the water to be treated in which the filter medium is immersed.   The water treatment device according to claim 8, claim 9, claim 11, claim 12, or claim 13, wherein the filter medium comprises an immersion flat membrane.   A pipe through which the water to be treated is circulated, and the pipe is made of an alkali-resistant or acid-resistant material. Item 15. The water treatment apparatus according to item 13 or claim 14.

Images