JP3241645B2 - Advanced treatment of wastewater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-order treatment of organic wastewater such as domestic wastewater and food wastewater, and a high-order treatment of wastewater suitable for high-order removal of nitrogen components.

[0002]

2. Description of the Related Art As a method of treating organic wastewater such as high-concentration domestic wastewater (sewage) and organic industrial wastewater, an activated sludge method,
In recent years, a suspended organism suspension method typified by a biological filtration method in which microorganisms are attached to a granular carrier and filtration is performed simultaneously with biological treatment, a biofilm method in which a biofilm is formed on the surface of the contact material, and microorganisms are comprehensively fixed. Biological treatment methods such as an inclusive immobilized biofilm method using a carrier or a self-granulating biofilm method in which microorganisms themselves form granules are used.

Conventionally, especially for sewage treatment, a contact oxidation biofilm method using a contact material has been adopted. However, due to problems such as a relatively slow treatment speed, peeling of the biofilm, and necessity of backwashing, there is a problem. At times, the floating organism method represented by the activated sludge method is often employed. However, the suspended microorganism method has a problem that it is difficult to remove nitrogen components, that is, denitrify, and it is not possible to perform high-order treatment of wastewater. Therefore, various modified methods (anaerobic / aerobic batch activated sludge method, anaerobic / aerobic activated sludge method) have been developed for high-order treatment, but a sufficient denitrification effect cannot be obtained. However, there is a problem that management is complicated.

[0004]

SUMMARY OF THE INVENTION The present invention is to provide a new high-order treatment method for wastewater, especially a method excellent in denitrification performance, which solves the above-mentioned problems of the prior art.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for treating wastewater, comprising the steps of denitrifying primary treated water subjected to aerobic biological treatment by anaerobic biofilm treatment using carbon fiber as a contact material. This is a high-level treatment method for wastewater.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation and effects of the present invention will be described below based on an example of the present invention.

FIG. 1 is a simplified flow sheet of an example of the method of the present invention.

In the drawing, reference numeral 1 denotes a screen device for removing solid impurities and the like in the water to be treated by a wastewater pretreatment device;
It consists of a flow control tank or the like that adjusts the flow rate as necessary, and performs a pretreatment of the drainage by an appropriate device according to the properties of the drainage. 2 is an aeration tank that performs floating organism treatment such as activated sludge treatment,
3 is a sedimentation tank for solid-liquid separation of the treated water from the aeration tank 2;
The supernatant water is sent to the next tank, and the sludge at the bottom is returned to the aeration tank 2. Reference numeral 4 denotes an anaerobic filter bed tank provided with carbon fiber strips, and reference numeral 5 denotes a post-treatment device comprising a sedimentation tank, a sterilization tank, and the like, which performs an appropriate post-treatment required for discharge or reuse.

When starting the treatment of the wastewater, seed sludge is introduced into the aeration tank 2 in the same manner as in the conventional activated sludge method,
The acclimatization is performed while circulating the waste water through the aeration tank 2 and the anaerobic filter bed tank 4. In this case, the anaerobic filter bed tank 4 is also acclimated under aerobic conditions, and if the biofilm is formed and then anaerobic, acclimation of the sludge can be performed in a short period of time. In the case of a carbon fiber contact material, sludge does not peel off even if this method is used. As a result of acclimation, the microflora corresponding to the properties of the wastewater is retained in each tank, biological oxidation is performed by aerobic treatment, and SS and BOD components are removed. The primary treated water is then separated into solid and liquid in a settling tank 3, and the supernatant water is guided to an anaerobic filter bed tank 4 provided with carbon fiber strips, and denitrified by an anaerobic biofilm formed on the carbon fiber strips. After being subjected to the processing (secondary processing, high-order processing), and subjected to necessary post-processing by the post-processing device 5, it is discharged or reused. A part of the sludge from the sedimentation tank 3 is returned to the aeration tank 2 (suspension biological treatment tank),
Maintain the MLSS in the tank at a predetermined level.

[0010] In the present invention, floating organisms are treated,
Since the denitrification treatment is performed in the anaerobic filter bed tank (anaerobic biofilm treatment) using the carbon fiber as the contact material, the nitrification treatment is performed on the fully nitrified primary treatment water. As described above, a sufficient denitrification treatment is performed by a carbon fiber biofilm having a high affinity for anaerobic microorganisms. Furthermore, before the primary treatment water is subjected to the secondary treatment (anaerobic filter bed tank), sedimentation treatment is performed to remove suspended components. In the secondary treatment, the biofilm strongly adheres to the carbon fiber strips, so the suspension is suspended. The efficiency of capturing turbid substances is high, the amount of suspended substances is extremely small,
Water quality is obtained so that precipitation treatment in post-treatment is almost unnecessary.

The carbon fiber strip used as the contact material for the anaerobic biofilm treatment of the present invention is a low modulus PA having a diameter of about 10 microns.
N-based carbon fibers are preferably used because they have high biocompatibility.
Further, the shape of the contact material may be a simply hanging fiber, or it may be designed so as to obtain a necessary contact area in consideration of the properties of drainage such as a strand woven of fibers and the shape of the tank. In the above description, an example in which the primary treatment is performed by the suspended microorganism method has been described. In this case, the primary treatment can be performed efficiently, but it is needless to say that it can be applied to other biological treatment, contact oxidation, and primary treatment water for biofilm treatment depending on the case, and depending on the properties of the wastewater and the primary treatment method. The primary treatment water can be directly introduced into the anaerobic filter bed tank without going through the sedimentation tank.When performing sedimentation separation, not only the sedimentation tank but also the membrane filter is immersed in the aeration tank, and the filtrate is anaerobically filtered. May be sent to

[0012]

EXAMPLE Oxidation ditch method using pretreated sewage from a sewage treatment plant and adding a small amount of skim milk and ammonium chloride as additional pollutants to the sewage treatment plant and acclimating standard activated sludge seeds as primary treatment The treated water treated with the above was subjected to a sedimentation treatment, and then guided to an anaerobic filter bed tank in which carbon fibers were hung, and subjected to a denitrification treatment. The results and processing conditions are shown in the table.

[0013]

[Table 1]

[0014]

According to the present invention, in the biological treatment method for wastewater, the primary treated water subjected to aerobic biological treatment is subjected to denitrification treatment by anaerobic biofilm treatment using carbon fiber as a contact material. High-grade denitrification treatment (higher-order treatment), which has great industrial utility value.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing one embodiment of the method of the present invention.

[Description of Signs] 1 Pretreatment device 2 Aeration tank 3 Sedimentation tank 4 Anaerobic filter bed tank 5 Posttreatment device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-84997 (JP, A) JP-A-3-146197 (JP, A) JP-A-54-160059 (JP, A) JP-A 8-84 290191 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C02F 3/34 101 C02F 3/30 C02F 3/00 C02F 3/10

Claims (3)

(57) [Claims] In a biological treatment method for wastewater, a primary treatment water subjected to an aerobic biological treatment is subjected to a denitrification treatment by an anaerobic biofilm treatment using carbon fiber as a contact material. Method. 2. The method for high-level treatment of wastewater according to claim 1, wherein after the primary treatment water is once subjected to solid-liquid separation, the supernatant water is subjected to the anaerobic biofilm treatment. 3. The high-order drainage water according to claim 1 or 2, wherein the microorganism is acclimated to the carbon fiber contact material under aerobic conditions to form a biofilm and then subjected to anaerobic treatment. Processing method.