JPH06496A - Advanced treatment of sewage - Google Patents

Abstract

PURPOSE:To treat nitrogen and phosphorus contained in sewage to be treated biologically and highly efficiently. CONSTITUTION:Nitrifiers are immobilized to a saddle type ceramic carrier for immobilizing miroorganisms. The aeration rate in a reactor 1 so controlled that the oxidation reduction potential of the water to be treated in the reactor 1 packed with the immobilization carrier is regulated to >=+100mV (Ag/AgCl electrode standard). A ferric chloride aqueous solution is added to the sewage and an insoluble phosphoric acid compound is deposited and filtered by the filter 2 of the succeeding stage wherein saddle type ceramic, sand or anthracite is packed therein. Thereby ammoniac nitrogen contained in sewage is nearly completely removed and the whole phosphorus can be treated to <=0.1mg/l.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an advanced treatment method for sewage treatment water.

[0002]

2. Description of the Related Art Conventionally, when performing advanced treatment for reuse of treated sewage water, the treated sewage water has been biologically treated by an aerobic filter bed. In other words, in order to highly remove the ammonia-form nitrogen remaining in the sewage treatment water, it is recognized that it is effective to use a filter bed with microorganisms attached. For example, the 28th Sewer Research Presentation Lecture , P. 849 ~
As described in 851 (1991), research on a processing technique using the principle has been conducted.

[0003]

When the biological and simultaneous removal of nitrogen and phosphorus from the sewage treatment water is carried out by the conventional method, if the conditions suitable for the removal of one are set, the other cannot be sufficiently removed.

Further, the removal performance of phosphorus is significantly affected by residual NO _X -N, etc., at the 28th Annual Conference on Sewerage Research, p. 523-525 (1991).

Regarding the reactor, the filter medium used in the aerobic filter bed for reuse of treated sewage water has hitherto been liable to cause dead volume or short-circuit flow of the water in the filter bed depending on its shape. There is a problem that efficient treatment is often not performed, such as clogging by the grown microbial membrane. Further, in the case of an aerobic filter bed using a granular carrier having a diameter of several mm, there are problems that the carrier flows in the reactor due to aerated air, and it is difficult to select a perforated plate that supports the filter medium. .

Another method for biologically removing phosphorus in sewage treatment is a method in which an anaerobic tank and an aerobic tank are installed in the reactor and water is alternately passed. However, in advanced treatment of sewage treatment water, the anaerobic degree in the anaerobic tank is low because the amount of organic substances contained in the inflowing sewage treatment water is small, and therefore the treatment effect is extremely low and it is difficult to implement.

The present invention provides an advanced treatment method for simultaneously removing phosphorus and nitrogen from sewage treatment water.

[0008]

Means for Solving the Problems The gist of the present invention is that, when biologically advanced treatment of nitrogen and phosphorus contained in sewage-treated water for reuse of sewage, the growth is slow, and the wash from the reactor is performed. The redox potential (ORP) of treated water obtained by treating the sewage treated water by a reactor in which immobilizing nitrifying bacteria that are easy to get out is immobilized on a saddle-type ceramics microorganism-immobilized carrier and further immobilizing the immobilized carrier on which nitrifying bacteria are immobilized is +100 mV ( (Ag / AgCl electrode standard) The aeration amount in the reactor is controlled to be more than the above, and in order to remove phosphorus remaining in the treated water, an aqueous ferric chloride solution is added to the treated water to precipitate an insoluble phosphate compound, and the latter stage Advanced treatment method of sewage treated water, characterized by filtering with a filter device filled with the saddle type ceramics, sand or anthracite Saddle-type ceramics It is preferable to use saddle-type ceramics containing granulated blast furnace slag as a main material for the microorganism-immobilized carrier and the filtering material of the filtration device.

[0009]

FIG. 1 shows an example of an apparatus for carrying out the advanced treatment method for sewage treatment water according to the present invention.

Activated sludge for treating sewage or industrial wastewater is put into a nitrification reactor 1 filled with saddle type ceramics, which is mainly made of granulated blast furnace slag. About 1
Airlift pipe 1 installed in the center of reactor 1 for one day
0 and the diffuser pipe at the bottom of the reactor 1 are used to immobilize the activated sludge on the saddle type ceramics while circulating the activated sludge. After the immobilization, the sewage treated water supply pump 13 supplies the sewage treated water to the reactor 1. At this time, the blower 7 is controlled and aerated so that the ORP potential detected by the ORP electrode 3 installed at the reactor outlet becomes +100 mV (Ag / AgCl electrode reference) or more.

As a method of controlling the blower 7, a method of controlling the inverter 9 by controlling PID is preferable.

The treatment time in the reactor 1 was set to 8 hours to acclimate and grow nitrifying bacteria, and then 6 hours
Reduced to 4 hours, 3 hours and 2 hours. The treatment is most preferably 3 hours.

The ferric chloride aqueous solution (35% aqueous solution) was added to the sewage treated water that had been subjected to nitrification treatment by the reactor 1 by using the ferric chloride aqueous solution supply pump 12, and about 5 ml (1 m treated water) of 1 m ³ of treated water. ^(About 2.38 g of FeCl ^{3 with} respect to ₃ ) is added. The insoluble phosphoric acid compound deposited by this addition is subjected to an upward flow filtration treatment by a filtration device filled with a saddle type ceramic as a filtration material.
Here, sand or anthracite can also be used as the filter medium with which the filter device is filled.

By this method ammonia form nitrogen 15
-20 mg / l, total phosphorus 0.5-2.0 mg / l Sewage treated water was highly treated, ammonia form nitrogen was not detected, and total phosphorus was 0.1 mg / l or less.

For removal of phosphorus, PAC or sulfuric acid band can be used as a metal salt instead of ferric chloride.

The insoluble phosphate compound that has precipitated and deposited on the filtration device can be easily removed by backwashing or withdrawing it from the lower part of the filtration device.

[0017]

[Example] Activated sludge mixed liquid (M
LSS: about 1500 mg / l) was put into a reactor filled with saddle type ceramics, and fixed by circulating it by an air lift pipe installed in the reactor for about 1 day. After immobilization is complete, ammonia form nitrogen 15-2
Treated actual sewage water of 0 mg / l and total phosphorus of 0.5 to 2.0 mg / l was passed so that the treatment time of the reactor was 8 hours. About 6 hours, 4 hours, 3 hours, about 1 week
It was shortened to 2 hours.

An aqueous ferric chloride solution (35%) was added to the treated water.
Filtration through a treated water 1 m ³ approximately 5ml against added (relative to the treated water 1 m ³ of about 2.38g as FeCl ₃₎ so that the filtering device filled with a saddle ceramics precipitated insoluble phosphate compounds did. The results are shown in Table 1. For comparison, Table 2 shows the results of processing by the conventional method.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

INDUSTRIAL APPLICABILITY According to the present invention, ammonia form nitrogen is almost completely removed from sewage treatment water, and total phosphorus is 0.1 mg / l.
It can be processed as follows.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an apparatus for carrying out an advanced treatment method for treated sewage according to the present invention.

[Explanation of symbols]

 1 Nitrification Reactor 2 Filtration Device 3 ORP Electrode 4 pH Sensor 5 ORP Controller 6 pH Controller 7 Blower 8 Blower 9 Inverter 10 Air Lift Pipe 11 Ferric Chloride Aqueous Solution Tank 12 Ferric Chloride Aqueous Solution Supply Pump 13 Sewage Treatment Water Supply pump

Claims (3)

[Claims] 1. Saddle-type ceramic microorganisms for nitrifying bacteria that grow slowly and are easy to wash out from the reactor when biologically advanced treatment of nitrogen and phosphorus contained in treated sewage to reuse sewage is carried out. Inside the reactor so that the oxidation-reduction potential of the treated water obtained by treating the sewage treated water by the reactor filled with the immobilized carrier on which the immobilized nitrifying bacteria are immobilized is +100 mV (Ag / AgCl electrode reference) or more. Control the amount of aeration in
In order to remove the phosphorus remaining in the treated water, an insoluble ferric chloride solution is added to the treated water to precipitate insoluble phosphoric acid compounds, which can be filtered by a filtration device filled with saddle-type ceramics, sand, or anthracite in the subsequent stage. An advanced method for treating treated sewage. 2. The method for advanced treatment of sewage treatment water according to claim 1, wherein the saddle-type ceramics microorganism-immobilized carrier is a saddle-type ceramics whose main raw material is granulated blast furnace slag. 3. The method for advanced treatment of sewage treatment water according to claim 1, wherein the filtering material of the filtering device is saddle-type ceramics whose main raw material is granulated blast furnace slag.