JPH04349995A - Water treatment - Google Patents

Abstract

PURPOSE:To separate bacteria efficiently using a simple device without any chemical by using magnetotaxis bacteria as microbes and separating waste water treated by the active bacteria from spent water treated by the action of a line of magnetic force, when organic waste water is purified by proliferating microbes in an organic spent water. CONSTITUTION:A magnetotaxis microbe (for example, Aguaspir; llummagnetotoacticum ATCC 31632) is used as a microbe when an organic waste water is purified by proliferating the microbe in the organic waste water. The waste water treated which contains the proliferating magnetotaxis bacteria is supplied to a magnetic field on which a magnet 9 acts in a bacterium separation device 7 and the magnetotaxis bacteria is gathered in a place in the waste water by the action of the line of magnetic force. In addition, the part, of the waste water, where the magnetotaxis bacteria is collected is extracted from a bottom flow path 11. Consequently, the bacteria can be separated efficiently using a simple device without the use of chemicals.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying organic wastewater using microorganisms.

0002

[Prior Art] In biological water treatment methods, microorganisms are grown in various types of wastewater such as urban sewage and industrial wastewater, and the wastewater is purified by allowing the microorganisms to ingest organic matter and inorganic salts contained in the wastewater. Unless microorganisms immobilized on a carrier are used, it is necessary to separate the grown microbial cells from the treated water. Conventionally, bacterial cell isolation has been carried out using methods such as gravity sedimentation, membrane separation, and coagulation sedimentation, but gravity sedimentation is only possible for microorganisms that form highly sedimentable flocs. However, the membrane separation method has the disadvantage of high equipment and operating costs, and the coagulation-sedimentation method requires the addition of a flocculant, which increases the cost, and the separated bacterial cells cannot be reused for water treatment. There is a problem in that it is necessary to continuously input seed sludge. In water treatment where microorganisms are immobilized on carriers, the above-mentioned problem of bacterial cell separation does not occur;
Since the amount of bacteria in the water to be treated cannot be increased too much, the purification efficiency is poor.

0003

[Problems to be Solved by the Invention] In view of the fact that conventional biological water treatment methods require a lot of expense for separating bacterial cells from treated water due to the above-mentioned reasons, it is an object of the present invention to The object of the present invention is to provide a biological water treatment method that enables low-cost bacterial cell separation.

0004

[Means for Solving the Problems] A novel biological water treatment method successfully provided by the present invention utilizes magnetotactic bacteria as microorganisms, and the treated wastewater containing the grown magnetotactic bacteria is subjected to a magnetic field. The method is characterized by separating magnetotactic bacteria from treated wastewater by feeding magnetotactic bacteria into the wastewater to cause magnetotactic bacteria to be unevenly distributed in the wastewater by the action of magnetic lines of force, and separating the wastewater in a portion containing the unevenly distributed magnetotactic bacteria. It is something.

[0005]

[Action] Magnetotactic b
A group of bacteria called ``acteria'' exist in ordinary activated sludge, although in small quantities, and have mycological properties that can be used alone to purify organic wastewater.
In addition, it has the property of taking iron ions into the bacterial cells, converting them into triferric tetroxide (Fe3O4), which is a magnetic substance, and storing it within the cells. Therefore, when placed in a magnetic field, the iron oxide within the bacteria body responds to the magnetic field lines, causing the bacteria to move in the direction of a specific magnetic pole (whether toward the north or south pole depends on the location on the earth, In the Northern Hemisphere, it goes towards the North Pole, but in the Southern Hemisphere, it goes towards the South Pole.) The water treatment method of the present invention utilizes this property of magnetotactic bacteria to concentrate and separate bacterial cells from treated water.

Specific examples of magnetotactic bacteria that can be used in the water treatment method of the present invention include Aquaspirillum mag.
netotacticum ATCC31632. The magnetotactic bacteria used can also be obtained by placing activated sludge-containing treated water in a magnetic field in a general activated sludge method to concentrate the magnetotactic bacteria in it, and then using it for wastewater treatment and subjecting it to concentration treatment using a magnetic field again. It may be separated from the activated sludge by repeating this operation. Except for the use of magnetotactic bacteria as microorganisms, the microbial treatment step in the water treatment method according to the present invention can be carried out in the same manner as conventional aerobic microbial treatment. However, since magnetotactic bacteria prefer microaerophilic conditions, the amount of aeration may be much smaller than in conventional activated sludge methods.

[0007] Wastewater that has been purified due to the growth of magnetotactic bacteria is sent to a magnetic field to separate the bacteria. When placed in a magnetic field with a magnetic flux density stronger than the earth's magnetic field, magnetotactic bacterial cells move in the direction of a specific magnetic pole and aggregate near the wall of the device on the magnetic pole side. Separate by any method. After the bacterial cells have been removed, the water is either discharged as is or undergoes a more advanced purification process. The collected sludge-like magnetotactic bacterial cells are returned to the treatment tank and reused for wastewater treatment. This bacterial cell separation operation also serves as a screening for magnetotactic bacteria to be used for purification, so even if miscellaneous bacteria enter the treatment tank along with the wastewater to be treated, the amount will not exceed a certain level. Excess of the bacterial cells separated by the bacterial cell separation device can also be used as a raw material for magnetite.

[0008]

Embodiment FIG. 1 shows an outline of the apparatus configuration for carrying out the present invention. The treatment tank 1 is connected to a raw water storage tank 3 through a pipe 2, from which it is supplied with wastewater to be treated. A stirring device 4 and an aeration device 5 are attached to the processing tank 1. The bacterial cell-containing wastewater in the treatment tank 1 is transferred to a bacterial cell separation device 7 through a pipe 6. The bacterial cell isolation device 7 is shown in FIG.
As shown in the enlarged view, there is a tubular drainage channel 8 that is divided into two upper and lower sections at the end, and an electromagnet 9 in which an N pole and a S pole are arranged with the former facing downward so as to sandwich the drainage channel 8. Consisting of An upper flow path 10 of the drainage flow path 8 branched at the end communicates with the discharge water outlet, and a lower flow path 11 communicates with the treatment tank 1 through a bacterial return pipe 12.

[0009] The wastewater to be treated has a pH of
, BOD, etc., are sent to the treatment tank 1 via the pipe 2, mixed with the seed sludge of magnetotactic bacteria that has been placed in advance, and stirred by the stirring device 4 and aerated by the aeration device 5 to make the microorganisms fine. Proceed with the purification process using magnetotactic bacteria while maintaining atmospheric conditions. Thereafter, the treated wastewater is sent to a bacterial cell separation device 7 via a pipe 6 along with magnetotactic bacteria. If the magnetic flux density of the electromagnet 9 is made sufficiently stronger than that of the earth's magnetism, the magnetotactic bacterial cells in the wastewater will be attracted to the north pole side while flowing through the wastewater flow path 8, and will be attracted to the north pole side of the wastewater flow path 8. It begins to flow along the tube wall. Then, it flows into the lower flow path 11 at the end,
The microbial cells are returned to the treatment tank 1 through the cell return pipe 12 and participate in the purification process again. The treated water from which the bacterial cells have been separated is passed through the upper flow path 1.
0 and head towards the discharge water outlet.

0010

[Effects of the Invention] As mentioned above, the present invention uses magnetotactic bacteria as microorganisms and separates the grown magnetotactic bacteria from treated wastewater by the action of magnetic lines of force, so it is more rapid than the gravity sedimentation method. Furthermore, bacterial cells can be easily separated using a simpler device and at a lower operating cost than the membrane separation method, and without requiring the addition of chemicals as in the coagulation-sedimentation method. Furthermore, since magnetotactic bacteria prefer microaerobic conditions, the amount of aeration can be significantly reduced compared to the conventional activated sludge method, resulting in less energy consumption. As described above, according to the present invention, it becomes possible to purify wastewater at an extremely low cost overall.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of an apparatus for implementing the present invention.

FIG. 2 is a schematic cross-sectional view of the bacterial cell separation device in FIG. 1.

[Explanation of symbols]

Claims (1)

[Claims] Claim 1: In purifying organic wastewater by growing microorganisms in the organic wastewater, magnetotactic bacteria are used as the microorganisms, and the treated wastewater containing the multiplied magnetotactic bacteria is supplied to a magnetic field. A water treatment method characterized by separating magnetotactic bacteria from treated wastewater by making magnetotactic bacteria unevenly distributed in wastewater by the action of magnetic lines of force, and separating the wastewater in a portion containing the unevenly distributed magnetotactic bacteria. .