KR20070006468A - A method for efficient treatment of wastewater using a rapid nitrification - Google Patents

Abstract

A wastewater treatment method which reduces nitrification time, and can treat wastewater by controlling the total nitrogen concentration of effluent is provided. A method for efficiently treating wastewater comprises the steps of: flowing in wastewater and a portion of microorganism sludge from a sedimentation tank and cultivating the portion of microorganism sludge at anaerobic conditions to discharge phosphorous from a phosphorous discharge tank and adsorb organic matters onto microorganisms at the same time; transferring an entire amount of a reaction solution from the phosphorous discharge tank and a portion of nitrified effluent from a nitrification tank to a denitrification tank and cultivating the reaction solution and the portion of nitrified effluent at anoxic conditions to denitrify nitrate nitrogen into nitrogen gas; transferring an entire amount of a reaction solution from the denitrification tank to a phosphorous absorbing and adsorbing tank, cultivating the reaction solution at aerobic conditions and denitrifying the cultivated reaction solution to remove remaining organic matters and allow phosphorous accumulated microorganisms to release PHA(polyhydroxyalkanoate) and absorb phosphorous excessively; transferring an entire amount of a reaction solution from the phosphorous absorbing and adsorbing tank to the sedimentation tank to separate microorganism sludge and supernatant from the reaction solution, return a portion of the separated microorganism sludge to the phosphorous discharge tank, and disuse the remainder of the microorganism sludge; and transferring supernatant separated from the sedimentation tank to a first stage nitrification tank to cultivate the supernatant at aerobic conditions, transferring the cultivated supernatant to a second stage nitrification tank to cultivate the supernatant at aerobic conditions, thereby nitrifying ammonia nitrogen or nitrite nitrogen, returning a portion of a reaction solution to the denitrification tank, and filtering and discharging the remainder of the reaction solution.

Description

A method for efficient treatment of wastewater using a rapid nitrification

1 is a view showing a reactor system used in the conventional A2O method.

FIG. 2 is a view showing a conventional reaction tank system including a phosphorus discharge tank, a bioadsorption tank, a primary precipitation tank, a nitrification tank, a denitrification tank, a phosphorus absorption tank, and a final precipitation tank, in which the membrane is installed.

FIG. 3 is a reactor system used in the method of the present invention, and FIG. 3A shows a reactor system composed of a phosphorus discharge tank, a denitrification tank, a phosphorus absorption and adsorption tank, a precipitation tank, first and second nitrification tanks, and a filtration tank, and FIG. 3B Represents a reactor system composed of a phosphorus discharge tank, a denitrification tank, a phosphorus absorption and adsorption tank, a precipitation tank and a nitrification tank equipped with a carrier or membrane.

Brief description of the symbols in the drawings:

RAS: Return activating sludge

Q: Inflow

The present invention relates to a method capable of efficiently and efficiently treating sewage.

As an example of a method for purifying sewage water, an A 2 O process has been known in the past, as shown in FIG. 1. According to the A2O process, it consists of the anaerobic tank phosphorus discharge tank, the anaerobic tank denitrification tank, the aerobic tank nitrification tank, the phosphorus absorption tank, and the precipitation tank. In the process, the sewage flowing into the phosphorus discharge tank is made anaerobic condition to release phosphorus, and then all of the reaction solution is sent to an anoxic tank denitrification tank and mixed with the sewage water returned from the aerobic tank nitrification tank and the phosphorus absorption tank to nitrate nitrogen. After degassing with nitrogen gas, all the reaction solution is transferred to the nitrification tank and the phosphorus absorption tank, which are aerobic tanks, and a part of the reaction solution is returned to the anoxic tank, and the remainder is transferred to the secondary settling tank, separated into microbial sludge and supernatant water. Some are returned to the phosphorus discharge tank and others are discarded. However, this method has a problem in that the amount of the reaction liquid increases and the capacity of the denitrification tank increases because the reaction liquid of the nitrification tank and the phosphorus absorption tank is returned to the denitrification tank in order to degas the nitrogen.

In addition, as shown in FIG. 2, Korean Patent Publication No. 482438 uses a reactor system composed of a phosphorus discharge tank, a biosorption tank, a primary precipitation tank, a nitrification tank, a denitrification tank, a phosphorus absorption tank, and a final precipitation tank. In order to induce phosphorus discharge by mixing some microbial sludge and inflow water from the final sedimentation tank, place biosorbing tank to lower the C / N ratio and then nitrify and denitrify the wastewater rapidly and efficiently. Is disclosed.

However, although the time required for nitrification was also shortened by the low C / N ratio, the sewage advanced treatment requires stable processing in the case of Korea, which has a clear four seasons, and requires a process that can shorten the treatment time.

An object of the present invention is to provide a wastewater treatment method which can shorten the nitrification time and can be treated by controlling the total nitrogen concentration in the effluent.

The present invention comprises the steps of introducing a portion of the microbial sludge from the sewage and sedimentation tank to incubate in anaerobic conditions to release phosphorus and adsorb organic matter to the microorganism;

Transferring all of the reaction solution from the phosphorus discharge tank and a part of the nitrified effluent from the nitrification tank to a denitrification tank and culturing in anoxic conditions to denitrify nitrate nitrogen with nitrogen gas;

Transfer all of the reaction solution from the denitrification tank to the phosphorus absorption and adsorption tank to incubate in aerobic state to remove organic matter remaining after denitrification, and to allow the accumulating microorganism to release PHA (polyhydroxyalkanoate) and to over absorb phosphorus step;

Transferring all of the reaction solution from the phosphorus adsorption and adsorption tank to the settling tank to separate the microbial sludge and the supernatant water, returning some of the separated microbial sludge to the phosphorus discharge tank, and discarding the remaining microbial sludge; And

The supernatant separated from the sedimentation tank is transferred to a first stage nitrification tank containing a carrier, incubated in aerobic conditions, and then transferred to a second stage nitrification tank containing a carrier, and cultured in aerobic conditions, followed by ammonia nitrogen or nitrite nitrogen. It is provided with a method for efficiently treating sewage water, including the step of nitrifying with nitric acid, returning part of the reaction solution to the denitrification tank, and filtering and discharging the rest.

In the method of the present invention, the nitrification tank is filled with a carrier. The carrier is a medium to which microorganisms can attach. The carrier may be any of known carriers. As the media of the nitrification tank, for example, porous plastics, ceramics, polypropylene and polyethylene can be used. The carrier preferably has a spherical or rectangular shape. Preferably, the porous polyethylene is spherical or rectangular. In addition, there is also a fibrous form of natural or synthetic fibers, usually 50 to 80% of the charge is used. Such carriers function to promote the attachment of microorganisms, thereby increasing the nitrification efficiency. In one embodiment of the present invention in particular, by filling the carrier in a container made of a stainless steel mesh specially designed to facilitate the contact of air, the nitrification efficiency is higher. In one embodiment of the method of the present invention, the carrier is collected in a mesh of a material such as stainless steel, so that the flow path through which the sewage flows is long.

In the method of the present invention, the nitrification tank is operated separately from the first stage nitrification tank and the second stage nitrification tank. In the first stage nitrification tank, the supernatant water separated from the settling tank is directly introduced and passed through the carrier filling layer, so that the floating organic matter (SS) is attached to and removed from the carrier, and at the same time for a relatively short time compared to the second stage nitrification tank. Nitrification is progressed, and the obtained nitrification water is transferred from the first stage nitrification tank to the second stage nitrification tank and cultured under aerobic conditions to carry out nitrification. At this time, the incubation time in the first stage nitrification tank and the second stage nitrification tank can be appropriately adjusted according to conditions such as raw water quality and discharge water quality.

3A is a diagram schematically showing an example of a sewage treatment system for carrying out the method according to the present invention and an example thereof. As shown in Fig. 3A, the treatment system is composed of a phosphorus discharge tank, denitrification, phosphorus absorption and adsorption tank, a precipitation tank, and a first stage, a second stage nitrification tank, and a filtration tank.

The present invention also comprises the step of introducing a portion of microbial sludge from sewage and sedimentation tank to incubate in anaerobic conditions to release phosphorus and adsorb organic matter to the microorganism; Transferring all of the reaction solution from the phosphorus discharge tank and a part of the nitrified effluent from the nitrification tank to a denitrification tank and culturing in anoxic conditions to denitrify nitrate nitrogen with nitrogen gas; Transfer all of the reaction solution from the denitrification tank to the phosphorus absorption and adsorption tank to incubate in aerobic state to remove organic matter remaining after denitrification, and to allow the accumulating microorganism to release PHA (polyhydroxyalkanoate) and to over absorb phosphorus step; Transferring all of the reaction solution from the phosphorus adsorption and adsorption tank to the settling tank to separate the microbial sludge and the supernatant water, returning some of the separated microbial sludge to the phosphorus discharge tank, and discarding the remaining microbial sludge; And the supernatant water separated from the settling tank is transferred to a nitrification tank filled with a carrier and the membrane is installed, incubated under aerobic conditions, and nitrified with ammonia nitrogen or nitrite nitrogen with nitrate nitrogen, and part of the reaction liquid is returned to the denitrification tank. It provides a method for efficiently treating the sewage, including the step of discharging the rest.

In the method of the present invention, the carrier is as described above.

In the method of the present invention, for example, a nonwoven fabric (50 to 100 µm), a reverse osmosis membrane, an ultrafiltration membrane, or a microfiltration membrane can be used as the membrane provided in the nitrification tank.

3B is a diagram schematically showing a sewage treatment system for carrying out the method according to the present invention in which a carrier or membrane is installed in a nitrification tank and an example of the treatment process thereof. As shown in Fig. 3A, the treatment system is composed of a phosphorus discharge tank, denitrification, phosphorus absorption and adsorption tank, a precipitation tank, and a nitrification tank equipped with a carrier or membrane.

The method of the present invention is described in more detail below with reference to FIGS. 3A and 3B.

(1) Inn Discharge tank

In the anaerobic phosphorus discharge tank, some, preferably 20% to 80%, of microbial sludge returned from the settling tank is mixed with influent to promote phosphorus release by promoting the formation of lower fatty acids in the body by inducing phosphorus release. . The mechanism of phosphorus release in phosphorus discharge tank is known as follows. Under anaerobic conditions of the phosphorus release tank, heterotrophs use organic acids produced through hydrolysis and fermentation as nutrients, but because of the lack of electron acceptors in the body, electrons and carbon are contained in cells such as polyhydroxybutyrate (PHB). Accumulate as a solid material. At this time, the active material such as acetyl coenzyme A is required for the polymerization of PHB, and the energy obtained from the hydrolysis of polyphosphate such as ATP is used for the synthesis thereof. The hydrolysis of the polyphosphate increases the concentration of phosphorus in the cell and, accordingly, releases it in vitro to increase the concentration of phosphorus in solution.

A removal resistant anaerobic microorganisms (PAOs) is Aero bakteo (Aerobacter), alkali jeneseu (Alcaligenes), Bacillus (Bacillus), Brevibacterium (Brevibacterium), Flavobacterium (Flavobacterium), Lactobacillus bacteria (Lactobacillus), micro Lactococcus ( Micrococcus ).

The incoming water quality of the incoming sewage is 200 to 150 mg of chemical oxygen demand (CODCr), 35 to 25 mg / l total nitrogen (TN) and 8 to 3 mg / l total phosphorus (TP). Suitable environmental conditions in the phosphorus discharge tank are 14 to 25 ° C., anaerobic conditions, 3,000 to 5,000 mg / l of microbial concentration (MLSS), and residence time is 20 to 30 minutes.

(2) Denitrification tank

The anoxic tank, which is an oxygen-free tank, converts all of the reaction solution of the phosphorus discharge tank and a part of the effluent containing nitrate nitrogen returned from the nitrification tank into a nitrogen gas by using denitrifying microorganisms to convert nitrogen nitrate to nitrogen gas using carbon as an electron donor. A denitrification reaction occurs.

In denitrifying microorganisms sets of the denitration Aero bakteo (Aerobacter), Bacillus (Bacillus), Pseudomonas (Pesudomonas), alkali jeneseu (Alcaligenes), Brevibacterium (Brevibacterium), Flavobacterium (Flavobacterium), Lactobacillus bacteria (Lactobacillus), Micrococcus and the like. More than 85% of the denitrifying microorganisms are permeable anaerobic microbes. Appropriate environmental conditions of the denitrification tank are preferably, the denitrification microbial concentration is 3,500 to 4,000 mg / l, the residence time is 1.0 to 2.5 hours, the concentration of dissolved oxygen should be close to zero. Check the organic denitrification state by attaching a redox potential (ORP) meter.

(3) Absorption  And Adsorption tank

ATP is synthesized by decomposing PHB (polyhydroxybutyrate) stored in phosphorus (PO ₄ -P) component accumulating microorganisms in a mixed solution introduced from a denitrification tank as an aerobic tank. Thus, phosphorous acid in solution is absorbed into the body of the microorganism and stored in cells in the form of inorganic phosphorus. This action is called luxury uptake and has an excellent effect on the removal of phosphorus from solution. In addition, in the phosphorus absorption and adsorption tank, organic matter remaining after the denitrification process is removed, and the surface of the microorganism is polished by the air supply to enhance the activity of the microorganism so that precipitation occurs in the precipitation tank.

Appropriate environmental conditions of the phosphorus absorption and adsorption tank are preferably at a temperature of 15 to 25 ° C., an air amount of 1.5 to 2.0 L / min, a microbial concentration (MLSS) of 3,500 to 4,000 mg / l, and a residence time of 15 to 20 minutes.

Removal microorganism Bacillus (Bacillus), MEGATHERIUM (Megaterium), Aero bakteo (Aerobacter), Pseudomonas (Pseudomonas), fluorescein sense (Fluorescene), Acinetobacter (Acinetobactor), Al kalko Cali Usui (Acalcocalius) and Proteus Proteus and the like.

(4) settling tank

The microbial sludge in the reaction liquid of the phosphorus absorption and adsorption tank is precipitated under the sedimentation tank to separate into supernatant water and microbial sludge, part of the microbial sludge is released, and a part of the microbial sludge to which the organic matter is attached is returned to the phosphorus discharge tank. The symbolic water is introduced into the nitric oxide tank.

Symbolic water separated from the sedimentation tank is 20 to 50 mg / l of chemical oxygen demand (CODCr), 20 to 30 mg / l of suspended solids (SS), 9 to 15 mg / l of total nitrogen (TN), 1 to 1 of total phosphorus (TP) 3 mg / l. At this time, the residence time in the precipitation tank is preferably 1.5 to 2.5 hours.

(5) Nitrifier

(5.1) Reactions in nitrifiers

The oxidizing tank is an aerobic tank, where the ammonia nitrogen in the supernatant introduced from the precipitation tank undergoes a nitrification reaction and is converted into nitrate nitrogen. The nitrification reaction is the first step and the conversion of ammonia nitrogen (NH ₃ -N) to nitrite nitrogen (NO ₂ -N) by the metabolism of nitrosomonas , a nitrifying microorganism, autotrophic bacteria. Nitro-bacter , a nitrifying microorganism, converts nitrite nitrogen (NO ₂ -N) into nitric acid (NO ₃ -N).

(5.2) In case of using two stage nitrification tank

In the case of using a two-stage nitrification tank, the appropriate conditions for each nitrification tank are preferably a temperature of 15 to 20 ° C. in the first and second stage nitrification tanks, and the dissolved oxygen concentration (DO) 3 in the first stage nitrification tank. -5 mg / l, residence time 15 minutes-30 minutes, dissolved oxygen concentration (DO) 3-5 mg / l in a 2nd stage nitrification tank, residence time 1-3 hours.

In the first stage nitrification tank, a small amount of suspended solids and organic substances in the influent are filtered through a carrier to oxidize the organic substances and nitrification of some ammonia nitrogen (NH ₃ -N). After minimizing the C / N ratio into the nitrification tank, the second stage nitrification tank performs nitrification with the C / N ratio minimized. As the carrier used in the nitrification tank, various carriers such as a porous carrier, a carrier having a large number of branches and a large pore, or activated carbon having a large pore can be used. In addition, the carrier may be used in any form in which nitrifiers are easily attached. The carriers are placed in a light fixed membrane so that a certain space is secured, for example, they are stacked alternately with each other so that water containing air passes through a serpentine channel, whereby oxygen, ammonia nitrogen, and small amounts of organic matter and nutrients are nitrified. Ensure good communication with the microorganisms.

This nitrifier can be used by autotrophs and heterotrophs, which are nitrifying bacteria, without competing for dissolved oxygen, so that nitrifying microorganisms predominate and the nitrification time is longer than conventional methods. It is shortened to almost 1/2 to 1/5. That is, autotrophic microorganisms grow under aerobic environmental conditions that require a large amount of dissolved oxygen, and other nutrient microorganisms are random microorganisms that do not require oxygen at the time of growth. In addition, there is almost no sludge production, and the first stage nitrification tank blows a lot of air for 5 to 10 minutes once every 5 to 15 days to remove accumulated sludge, and the second stage nitrification tank is 5 to 10 minutes every 1 to 3 months. Blow a lot of air while removing sludge that has accumulated. Generally, the first stage nitrification tank is OK once a month, and the second stage nitrification tank is possible once every six months.

In the method of the present invention, the nitrification tank is filled with a carrier. The carrier is a medium to which microorganisms can attach. The carrier may be any of known carriers. As the media of the nitrification tank, for example, porous plastics, ceramics, polypropylene and polyethylene can be used. The carrier preferably has a spherical or rectangular shape. Preferably, the porous polyethylene is spherical or rectangular. In addition, there is also a fibrous form of natural or synthetic fibers, usually 50 to 80% of the charge is used. Such carriers function to promote the attachment of microorganisms, thereby increasing the nitrification efficiency. In one embodiment of the present invention in particular, by filling the carrier in a container made of a stainless steel mesh specially designed to facilitate the contact of air, the nitrification efficiency is higher. In one embodiment of the method of the present invention, the carrier is collected in a mesh of a material such as stainless steel, so that the flow path through which the sewage flows is long.

The concentration of supernatant from the nitrifier is 15-20 mg / l of chemical oxygen demand (CODCr), 10-20 mg / l of biological oxygen demand (BOD), 5-15 mg / l of suspended solids (SS), and total nitrogen. (TN) 3-12 mg / l, total phosphorus (TP) 0.4-1.1 mg / l. Sewage water treated in the nitrification tank is partially returned to the denitrification tank, and the remainder is filtered to remove the suspended solids (SS) and discharged.

(5.3) When using nitrification tank equipped with carrier or membrane

When using nitrification tanks using a carrier or membrane, the appropriate conditions for each nitrification tank are preferably, in the nitrification tank, the temperature is 15 ° C. to 20 ° C., dissolved oxygen concentration (DO) 3 to 5 mg / l, and microbial concentration ( MLSS) 3,500 to 9,000 mg / l, residence time 1 to 3 hours.

In the sedimentation tank, supernatant containing organic matter is introduced into a nitrification tank equipped with a carrier or membrane to nitrify ammonia nitrogen (NH ₃ -N). Since the carrier or the membrane is installed, the concentration of the nitrifying microorganism is increased by increasing the microbial concentration (MLSS) when performing the nitrification reaction, there is an advantage that the nitrification of ammonia nitrogen can be made quickly. Therefore, the nitrification reaction time can be shortened.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, these examples are for illustrative purposes only and the scope of the present invention is not limited to these examples.

Example

First, the specification for each group used in the present invention is as follows.

Phosphorus discharge tank is 3.2mm thick acrylic resin, 70mm in diameter and 220mm in height, and the mixing device of return sludge of influent and sedimentation tank is installed, and it is equipped with microorganism by installing Oxidation reduction potential (ORP) sensor and MLSS sensor. Check the status of, manufactured a separate operating device.

The denitrification tank is 3.2mm thick, cylindrical, 12mm in diameter and 370mm in height. Agitator is installed in the center of the tank and the stirring speed is 40rpm.

The phosphorus absorption and adsorption tank is 3.2mm thick acrylic resin cylinder, 70mm in diameter and 220mm in height, and ceramic diffuser is installed at the bottom of the tank.

The sedimentation tank is acrylic and 3.2mm thick cylindrical and conical, with a diameter of 120mm and a height of 220mm. A scraper with a diameter of 190mm is installed at the center of the tank. The rotation speed is 0.3rpm.

The first stage of the nitrification tank was made of acrylic resin 3.2mm thick, cylindrical, 70mm in diameter, 220mm in height, stainless steel wire mesh 25mm in diameter, 30mm in height, and filled with porous media inside. The ceramic diffuser was installed at the top, and the dissolved oxygen sensor was installed at the top to measure the dissolved oxygen concentration.

The second stage of the nitric oxide tank was 3.2mm thick, cylindrical, 120mm in diameter, 295mm in height, and the structure was installed with a stainless steel wire 25mm in diameter, 30mm in height, and filled with a porous carrier inside. A ceramic diffuser was installed at the bottom of the tank, and a dissolved oxygen sensor was installed at the top to measure the dissolved oxygen concentration.

The filtration device was filled with a sand filter in an acrylic resin thickness of 3.2 mm, a cylindrical shape of 50 mm in diameter, and a height of 212 mm.

When membranes are installed, microfiltration (MF), ultrafiltration (UF) and reverse osmosis (RO) membranes can be used for the membrane type.The membrane material is raw water characteristics of sewage such as polysulfone, polyamide and polyethylene. The membrane can be selected and used accordingly. The carrier (media) may be made of a material such as porous plastic and polyethylene, may be used in the shape of spherical and long direction, and may also be used in the form of natural fibers or synthetic fibers.

Example 1

In this embodiment, the sewage treatment was performed according to the configuration and process of the reactor as shown in FIG. 3A.

The feed sludge was mixed and introduced into the phosphorus discharge tank, varying depending on the conditions of the phosphorus discharge tank and the quality of the incoming raw water from 0.2Q to 0.8Q returned from the sewage and the sedimentation tank flowing in the amount of 40L / day. In this example, the experiment was performed at 0.5Q. The chemical oxygen demand (CODcr) of sewage in the phosphorus discharge tank (CODcr) 140 mg / L, the biological oxygen demand (BOD) 180mg / L, suspended solids (SS) 210mg / L, total nitrogen (TN) 35.2mg / L, total phosphorus ( TP) 7 mg / L of sewage was incubated in the phosphorus discharge tank for 0.5 hours to over-release phosphorus.

While transferring all of the reaction solution to the denitrification tank and returning to the denitrification tank while changing the amount of return from the final filtration tank to 0 Q to 3 Q according to the discharge water concentration, the microorganism MLSS concentration in the denitrification tank was 4,000 mg / L, Nitrate nitrogen was reduced and degassed with nitrogen gas with a residence time of 2.0 hours.

As a result, all of the reaction liquid of the obtained denitrification tank was transferred to the phosphorus absorption and adsorption tank. The microbial MLSS concentration of the aerobic tank phosphorus absorption and adsorption tank was 3,800 mg / L, air volume 1.2L / min, and the phosphorus was absorbed into the microorganisms using the accumulation microorganisms and the surface of the microorganism was polished. .

Next, all of the mixture of the phosphorus absorption and adsorption tank is sent to the settling tank to separate the microbial sludge and the supernatant water for 2.5 to 3.0 hours, and the separated microbial sludge is 0.2Q to 0.8Q (it changed depending on the situation, but mainly 0.5 Operation at Q) was returned to the phosphorus discharge tank, the rest was drawn off and disposed of, and the supernatant water was transferred to the first stage of the nitrification tank.

The symbolic water flowing into the first stage of the nitrification tank is chemical oxygen demand (CODcr) 32.7 mg / L, biological oxygen demand (BOD) 44.2 mg / L, suspended solids (SS) 23 mg / L, total nitrogen (TN) 14.0 mg / L, total phosphorus (TP) 1.3 mg / L. In the first stage of the nitrification tank, air was injected so that the dissolved oxygen (DO) concentration in the upper part was 3 to 5 mg / L, and a 20 mm diameter pipe was connected to the lower stage to transfer all of the first stage nitrification reaction solution to the lower stage of the nitrification tank. .

The ammonia nitrogen contained in the inflow water was oxidized to nitrate nitrogen in an aerobic state so that the same dissolved oxygen (DO) concentration as the first stage of the nitrification tank was 3 to 5 mg / L. A part of the mixture of the two stages of nitrification tank was returned to the denitrification tank at a rate of 0Q to 3Q, and the rest was discharged through the filtration tank. Effluents include chemical oxygen demand (COD) 10 mg / L, biological oxygen demand (BOD) 8.1 mg / L, suspended solids (SS) 2.9 mg / L, total nitrogen (TN) 2.5 mg / L, total phosphorus (TP) 0.2 mg / It was L.

Example  2

In this example, the sewage water was treated according to the configuration and reaction sequence of the reactor as shown in FIG. 3B.

Sewage returned from the sewage and sedimentation tanks flowing in the amount of 40 L / day was returned to the phosphorus discharge tank by 0.3Q-0.8Q. Chemical oxygen demand (CODcr) 140 mg / L for sewage in a phosphorus discharge tank, biological oxygen demand (BOD) 180 mg / L, suspended solids (SS) 210 mg / L, total nitrogen (TN) 35.2 mg / L, total phosphorus (TP) 7 mg / L of sewage was incubated in a phosphorus discharge tank for 0.5 hours to over-release phosphorus from microorganisms.

At the same time, all the reaction solution is transferred to the denitrification tank, and the treated water which has passed through the membrane in the nitrification tank is returned to the denitrification tank at 0Q to 3Q and mixed, and the microorganism MLSS concentration in the denitrification tank is 4,000 mg / L and the residence time is 2.0 hours. Was reduced and degassed with nitrogen gas.

As a result, all of the reaction liquid of the obtained denitrification tank was transferred to the phosphorus absorption and adsorption tank. The microbial MLSS concentration of the aerobic tank phosphorus absorption and adsorption tank was 3,800 mg / L, air volume 1.2L / min, and the phosphorus was absorbed into the microorganisms using the accumulation microorganisms and the surface of the microorganism was polished. .

Next, all of the mixed pressure of the phosphorus absorption and adsorption tank is transferred to the settling tank and separated into microbial sludge and supernatant water for 2.5 to 3.0 hours, a part of the microbial sludge is returned to the phosphorus discharge tank, and the rest is discarded and the supernatant water is membrane ( membrane) was introduced into the nitrification tank. Symbolic water content is chemical oxygen demand (COD) 32.7 mg / L, biological oxygen demand (BOD) 44.2 mg / L, suspended solids (SS) 23 mg / L, total nitrogen (TN) 14.0 mg / L, total phosphorus (TP) 1.3 It was introduced into the nitrification tank at the concentration of mg / L, and air was injected so that the dissolved oxygen (DO) concentration of the upper part was 3 to 5 mg / L, and the ammonia nitrogen was used as the nitrification microorganism with the microorganism MLSS concentration of 4,000 to 9,000 mg / L. After oxidizing with nitric acid, a portion of the membrane permeate was returned to 0Q to 3Q in a denitrification tank, and the remainder was discharged through a discharge or filtration tank depending on the desired treatment water quality. Emissions are 8 mg / L chemical oxygen demand (COD), 5 mg / L biological oxygen demand (BOD), 2.5 mg / L suspended solids (SS), 2.2 mg / L total nitrogen (TN), 0.1 mg / L total phosphorus (TP) It was L.

Comparative example

The reactor system used in this comparative example was treated by introducing sewage water according to the reactor configuration and reaction sequence as shown in FIG.

The reaction tank shown in FIG. 2 is provided with a phosphorus discharge tank, an adsorption tank, a primary precipitation tank, a nitrification tank, a denitrification tank and a phosphorus absorption tank. On the other hand, the reaction tank used in the embodiment of the present invention (Fig. 3a, 3b) is composed of a phosphorus discharge tank, denitrification tank, phosphorus absorption and adsorption tank, precipitation tank and nitrification tank.

The sewage introduced in the amount of 40 L / day and the sludge returned from the final settling tank were mixed and introduced into the phosphorus discharge tank. Chemical oxygen demand (CODcr) 140 mg / L for sewage in a phosphorus discharge tank, biological oxygen demand (BOD) 180 mg / L, suspended solids (SS) 210 mg / L, total nitrogen (TN) 35.2 mg / L, total phosphorus Sewage water of 7 mg / L (TP) was incubated for 0.5 hour in a phosphorus discharge tank to over-release phosphorus from microorganisms.

Next, all of the inflow water is transferred from the phosphorus discharge tank to the adsorption tank, and the organic matter is attached to the microorganisms under the conditions of 3,300 mg / L of microorganism MLSS concentration, 1.2 L / min of air volume and 15 minutes of residence time, and then all of the mixed liquid is placed in the primary precipitation tank. To separate the microbial sludge and the supernatant with a residence time of 1.5 hours, discharge some of the microbial sludge and transfer the remainder to the denitrification tank, chemical oxygen demand (CODCr) 30.1 mg / l, biological oxygen demand (BOD) Symbolic water with 20,6 mg / l, suspended solids (SS) 20.2 mg / l, total nitrogen (TN) 13.2 mg / L, total phosphorus (TP) 2 mg / l is introduced into the nitrifier and the volume of injected air is 5 L / min Under a condition of 2 hours residence time, a part of the mixed solution was returned from the intake tank to the nitrification tank in an amount of 0.5Q to maintain a high concentration of 3,900 mg / l. As a result, ammonia nitrogen contained in the influent in the aerobic state was oxidized to nitrate nitrogen in the nitrification tank.

Next, chemical oxygen content (CODcr) 26.3 mg / l, biological oxygen demand (BOD) 12.5 mg / l, suspended solids (SS) 7.6 mg / l, total nitrogen (TN) 11.1 mg / l, total phosphorus (TP) 0.5 mg / l of all mixed sludge was introduced into the denitrification tank, and mixed with 11,000 mg / L of the microbial sludge which had been introduced into the denitrification tank from the primary sedimentation tank at a rate of 0.14 to 0.16 L / min. Nitrate nitrogen was reduced and degassed with nitrogen gas under conditions of mg / L and residence time of 1.5 hours. Total nitrogen (TN) obtained as a result 4.2. The total mixture (mg / l, total phosphorus (TP) 0.43 mg / l (measured in the supernatant water after separation of the supernatant) was introduced into the absorption tank, followed by the microbial concentration of 3,800 mg / l and the injected air volume of 1.8 L / min, phosphorus is absorbed into the microorganisms using the accumulation microorganisms under the conditions of 15 minutes of residence time, part of the mixed solution is returned to the nitrification tank in the amount of 0.5Q from the phosphorus absorption tank, and the remainder is transferred to the final settling tank and the microorganism sludge and symbol After separating into water, a part of the microbial sludge was returned to the phosphorus discharge tank at a rate of 0.14 to 0.161 L / min and the supernatant water was discharged.

The discharged symbolic water, or treated water, has a chemical oxygen demand (CODcr) of 10.3 mg / l, a biological oxygen demand (BOD) of 7.6 mg / l, and suspended solids (SS) 4.9. mg / l, total nitrogen (TN) 4.1 mg / l, total phosphorus (TP) 0.2 mg / l.

As shown in the present embodiment as described above, by the method of the present invention, sewage water having a low C / N ratio, which is a ratio of organic matter concentration and nitrogen concentration, is introduced into a two-stage nitrification tank or a nitrification tank equipped with membranes, and the sewage water whose nitrification is the key. It was confirmed that nitrification can be carried out in a short time, and the target effluent total nitrogen (TN) concentration can be controlled.

Table 1 summarizes the treatment results of sewage according to the examples and comparative examples of the present invention.

As shown in Table 1, the chemical oxygen demand (CODcr), biological oxygen demand (BOD), suspended solids (SS), total nitrogen (TN) of the treated water according to Examples 1 and 2 according to the process of the invention And it was found that the concentration of total phosphorus (TP) is higher than the comparative example according to the conventional method. In addition, according to the method of the present invention, not only the processing efficiency is high, but also the processing method takes about 7 hours compared with 8 hours, and the effect is reduced by about 12.5%.

This effect is achieved by arranging the phosphorus discharge tank and the denitrification tank, and then placing the phosphorus absorption and adsorption tank in an aerobic state with a residence time of about 15 to 30 minutes. The denitrification process is performed smoothly by releasing phosphorus from the microorganism and adsorbing the organic material to the microorganism to secure nutrients necessary for denitrification in the denitrification tank, and removing the organic matter remaining after denitrification in the denitrification tank. It is believed that this is because the surface of the microorganism is cleaned to enhance the activity of the microorganism so that it can be introduced from the nitrification tank later and perform the nitrification process efficiently. In addition, according to the method of the present invention, by separating the mixture of the phosphorus absorption and the adsorption tank into the microorganism and the supernatant water using the precipitation tank, the organic matter concentration of BOD is 30mg / L or less, C / N / ratio is low, and the floating material is almost By allowing clean symbolic water to be introduced into the nitrification tank, nitrification is possible in a short time, and part of the nitrified effluent can be returned to the denitrification tank for denitrification to adjust the target total nitrogen (TN) concentration so that the total nitrogen ( TN) has the advantage that the target water quality can be achieved even with a short residence time up to 5 mg / L or less.

Claims (3)

Introducing a portion of the microbial sludge from sewage and sedimentation tank to incubate in anaerobic conditions to release phosphorus and adsorb organic matter to the microorganism; Transferring all of the reaction solution from the phosphorus discharge tank and a part of the nitrified effluent from the nitrification tank to a denitrification tank and culturing in anoxic conditions to denitrify nitrate nitrogen with nitrogen gas; Transfer all of the reaction solution from the denitrification tank to the phosphorus absorption and adsorption tank to incubate in aerobic state to remove organic matter remaining after denitrification, and to allow the accumulating microorganism to release PHA (polyhydroxyalkanoate) and to over absorb phosphorus step; Transferring all of the reaction solution from the phosphorus adsorption and adsorption tank to the settling tank to separate the microbial sludge and the supernatant water, returning some of the separated microbial sludge to the phosphorus discharge tank, and discarding the remaining microbial sludge; And The supernatant separated from the sedimentation tank is transferred to a first stage nitrification tank containing a carrier, incubated in aerobic conditions, and then transferred to a second stage nitrification tank containing a carrier, and cultured in aerobic conditions, followed by ammonia nitrogen or nitrite nitrogen. Nitrifying with nitrate nitrogen, part of the reaction liquid is returned to the denitrification tank and the remaining is filtered and discharged. The method of claim 1 wherein the carrier is entrapped in a net. Introducing a portion of the microbial sludge from sewage and sedimentation tank to incubate in anaerobic conditions to release phosphorus and adsorb organic matter to the microorganism; Transferring all of the reaction solution from the phosphorus discharge tank and a part of the nitrified effluent from the nitrification tank to a denitrification tank and culturing in anoxic conditions to denitrify nitrate nitrogen with nitrogen gas; Transfer all of the reaction solution from the denitrification tank to the phosphorus absorption and adsorption tank to incubate in aerobic state to remove organic matter remaining after denitrification, and to allow the accumulating microorganism to release PHA (polyhydroxyalkanoate) and to over absorb phosphorus step; Transferring all of the reaction solution from the phosphorus adsorption and adsorption tank to the settling tank to separate the microbial sludge and the supernatant water, returning some of the separated microbial sludge to the phosphorus discharge tank, and discarding the remaining microbial sludge; And The supernatant separated from the sedimentation tank is transferred to a nitrification tank equipped with a carrier or membrane, incubated under aerobic conditions, and nitrified with ammonia nitrogen or nitrite nitrogen with nitrate nitrogen, and part of the reaction solution is returned to the denitrification tank and the rest is discharged. A method for efficiently treating sewage, comprising the steps of:

Images