JPH04235799A - Method and apparatus for treating organic waste water - Google Patents

Abstract

PURPOSE:To efficiently treat org. waste water by a method wherein org. waste water containing oils and fats is preliminary separated into an oils and fats component and water and the separated water is treated in a biological treatment process while the oils and fats components is treated in an aerobic decomposition process to be decomposed biologically and the obtained bacteria- containing water of the decomposition process is injected in the separated water or the aforementioned biological treatment process. CONSTITUTION:Org. waste water containing oils and fats is preliminary separated into an oils and fats component 9 and water 12 and the separated water 12 is treated in a biological treatment process 5. The oils and fats component 9 is treated in an aerobic decomposition process to be biologically decomposed and the obtained bacteria-containing water 11 of the decomposition process is injected in the separated water 12 or the biological treatment process 5. As a result, the org. waste water containing the oils and fat component can be efficiently treated without generating the trouble based on the oils and fats component.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the treatment of organic wastewater, and more particularly to a method and apparatus for the biological treatment of organic wastewater containing fats and oils.

0002

BACKGROUND OF THE INVENTION Recently, the number of facilities for treating domestic wastewater including kitchen wastewater has been increasing, but as eating habits become more Westernized, the wastewater contains more oil and fat. As a result, problems such as pipes, screens, etc. becoming clogged with solidified oil occur in domestic wastewater treatment facilities. In addition, the sludge generated from such treatment facilities is transported to human waste treatment plants and treated as septic tank sludge, but septic tank sludge contains high concentrations of oil and fat (usually measured as n-hexane extractables). Because of the presence of oil in septic tank sludge, there are many problems such as clogging of screens that separate impurities from septic tank sludge and problems caused by solid oils and fats that become concentrated and enlarged during the treatment process. However, there has been no suitable method for dealing with such problems.

0003

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for treating organic wastewater containing oils and fats, which can efficiently treat wastewater containing oils and fats as described above without any trouble. purpose.

0004

[Means for Solving the Problems] In order to achieve the above object, in the present invention, in the treatment of organic wastewater containing oil and fat,
The wastewater is preliminarily separated into oil and fat and separated water, the separated water is treated in a biological treatment process, and the oil and fat is treated in an aerobic decomposition process for biological decomposition, and the resulting microorganism-containing liquid from the decomposition process is The present invention provides a method for treating organic wastewater containing oil and fat, which comprises injecting the separated water into the separated water or into a biological treatment process of the separated water.

[0005] In order to achieve the other objects mentioned above, the present invention also provides an oil-water separation tank for separating the oil and fat content of oil-containing organic wastewater, an aeration tank for biologically treating the separated water, and an oil-water separation tank for separating the oil and fat content of organic wastewater containing oil and fat. It consists of an aerobic decomposition tank for biologically decomposing the water, and a passageway is provided to introduce the microorganism-containing liquid from the decomposition tank into one of the separated water flow paths from the oil-water separation tank to the aeration tank. This is an apparatus for treating organic wastewater containing oil and fat.

[0006] In the above treatment method, it is preferable to add fat-degrading bacteria to the biological aerobic decomposition step of fats and oils. Specifically, the method of decomposing oil by allowing Pseudomonas, yeast, Bacillus, and other known oil-degrading bacteria, which are fat-degrading bacteria, to live there, or adding a commercially available biological preparation for fat-degrading, to decompose the oil. or both may be used together. In addition, during the biological treatment process of separated water, oil and fat are collected in a sedimentation tank.
In other cases, it may be partially concentrated and separated, but such fats and oils can be treated by introducing them into an aerobic fat and oil decomposition process.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below with reference to the drawings, but the present invention is not limited thereto. Example 1
An embodiment in which the present invention is applied to the treatment of septic tank sludge will be described with reference to FIG.

The septic tank sludge 1 passes through an oil-water separation tank 2, and after coarse impurities are removed by a rotary screen 3 with an opening of 0.7 mm, it is stored in a storage tank 4. After the BOD components of the stored septic tank sludge are oxidized and decomposed in the activated sludge aeration tank 5, the activated sludge is separated into solid-liquid into thickened sludge 7 and supernatant water 8 in the settling tank 6, and the thickened sludge is returned to the aeration tank. A part of the thickened sludge is discharged outside the system as surplus sludge 15. In the biological treatment process, in addition to the activated sludge method, known biological treatment methods such as a method using biofilm attached to a medium and an anaerobic digestion method may be used. Moreover, it can be applied not only to BOD treatment but also to nitrogen and phosphorus treatment methods. The oil/fat component 9 separated in the oil/water separation tank 2 is subjected to an oil/fat decomposition step 10 under aerobic conditions.
is introduced and decomposed, and at the same time, fat- and oil-degrading bacteria proliferate. The decomposition liquid 11 of this step is injected into the separated water 12 of the oil-water separation step 2, the storage tank, or the activated sludge aeration tank, and the remaining oil and fat in the oil-water separation tank 2 is decomposed. In the fat and oil decomposition step 10, wild oil and fat decomposing bacteria naturally proliferate due to the abundance of oil and fat, but by adding artificially grown oil and fat decomposing bacteria (biological preparation) 13 to this step, The decomposition rate of fats and oils is accelerated, and the practicality can be greatly improved. It is desirable to add a biological preparation in advance to the fat and oil decomposition step 10 in order to perform the process smoothly. In the biological treatment process, fats and oils may be partially concentrated and separated in a settling tank or elsewhere, but such fats and oils 14 may be transferred to the fats and oils decomposition process 10.

Embodiment 2 Next, the present invention was applied to an existing septic tank sludge treatment device that handles a large amount of water from a combined type septic tank by adding an oil/water separation tank, an oil/fat decomposition tank, and piping, and partially modifying the system. The following effects were obtained. Before modification, coarse SS of septic tank sludge clogged after 4 to 7 hours.
A screen with 1 mm openings for removal can now be operated smoothly for 20 to 40 hours without any blockage problems. Also, the generation of oil-containing scum that had floated on the surface of the activated sludge settling tank has disappeared.

[0010] A diffuser pipe was installed in the added fat and oil decomposition tank, and aeration was carried out at a rate of 2 kg-O2/m3.day. Further, the residence time of the fats and oils (including a large amount of water) in the fats and oils decomposition tank was 2 to 5 days. A commercially available biological preparation for decomposing fats and oils was added to the same tank at a concentration of 20 to 50 ppm based on the inflowing fats and oils. Since the effects per weight of the biological preparations differed depending on the product, the amount added was increased or decreased as appropriate after confirming the effects.

[0011]

Effects of the Invention According to the present invention, since only fats and oils are separated and treated, it is possible to prevent clogging of the screen that separates impurities in the septic tank sludge, and also to prevent the surface of the activated sludge settling tank from becoming clogged. The oil-containing scum that had floated to the surface disappeared, and the troubles caused by oil and fat were resolved.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing an organic wastewater treatment apparatus of the present invention.

[Explanation of symbols]

1 Septic tank sludge, 2 Oil-water separation tank, 3 Screen, 4 Storage tank, 5 Activated sludge aeration tank, 6 Sedimentation tank, 7 Thickened sludge, 8 Supernatant water, 9 Oil and fat, 1
0 fat and oil decomposition process, 11 decomposition liquid, 12 separated water, 13 fat and oil degrading bacteria, 14 concentrated fat and oil content

Claims (2)

[Claims] [Claim 1] In the treatment of organic wastewater containing oil and fat,
The wastewater is preliminarily separated into oil and fat and separated water, the separated water is treated in a biological treatment process, and the oil and fat is treated in an aerobic decomposition process for biological decomposition, and the resulting microorganism-containing liquid from the decomposition process is A method for treating organic wastewater containing oil and fat, comprising injecting the separated water into the separated water or into a biological treatment process of the separated water. Claim 2: An oil-water separation tank for separating oil and fat from oil-containing organic wastewater, an aeration tank for biologically treating the separated water, and an aerobic decomposition tank for biologically decomposing the oil and fat. An apparatus for treating organic wastewater containing oil and fat, characterized in that a passage is provided for introducing a microorganism-containing liquid from a decomposition tank into one of the separated water flow paths extending from the oil-water separation tank to the aeration tank.