KR20040018605A - Apparatus for Treatment of Domestic Wastewater Combining Continuous SBR and Contact Aeration Tank and Method Therefor Using the Apparatus - Google Patents

Abstract

PURPOSE: Provided are an apparatus and a method for treating wastewater using a sequencing batch reactor (SBR) and a contact aeration tank, which can treat wastewater with high efficiency by synergy effect of the SBR and the contact aeration tank. CONSTITUTION: The apparatus comprises a wastewater tank(2) for storing wastewater; a sequencing batch reactor(3) with a tank having a wastewater inlet at the bottom thereof and a treated water outlet at an upper portion thereof, an impeller(12) connected to an agitator(10), an air diffuser(13) connected to an air supply unit(8), and a sludge drain for discharging excess sludge, wherein the tank is operated under a settling condition for settling pollutants in wastewater by gravity force, under a wastewater influent/effluent condition, under an anoxic condition for reducing nitrate to nitrogen, under an anaerobic condition for releasing phosphorous from denitrifying microorganisms, and under aerobic condition for nitrifying nitrogen, luxury uptake of phosphorous, multiplication of microorganisms in turn; a contact aeration tank(4) with a water inlet and an outlet at an upper portion thereof, an air diffuser(16) and contact media(15) onto which microorganisms are immobilized for biologically treating wastewater; and a return pipe(21) for returning effluent water of the contact aeration tank(4) to the sequencing batch reactor(3). The method comprises the steps of (a) settling wastewater and separating into a first sludge layer and a first decant water in a sequencing batch reactor, (b) introducing wastewater to the first sludge layer from the bottom of the reactor while discharging the first decant water by the same amount of wastewater introduced into the reactor, (c) reducing NOx-N to N2 by denitrifying microorganisms by operating the reactor under an anoxic condition, (d) releasing phosphorous from denitrifying microorganisms under anaerobic condition, (e) nitrifying N using organic material, causing luxury uptake of phosphorous by microorganisms, and discharging the microorganisms under aerobic condition, (f) biologically treating remained pollutants in the outflow of the sequencing batch reactor by bringing the pollutants into contact with air and contact media in a contact aeration tank, (g) returning a portion of the effluent water of the contact aeration tank to the sequencing batch reactor and transferring the other portion of the effluent water to a settling tank, thereby separating it into a second sludge layer and a second decant water.

Description

Apparatus for Treatment of Domestic Wastewater Combining Continuous SBR and Contact Aeration Tank and Method Therefor Using the Apparatus}

The present invention relates to a sewage treatment apparatus combining a continuous batch single reactor and a contact aeration tank, and to a sewage treatment method capable of more efficiently removing organic substances and nutrients in domestic sewage using the same.

Since the first modern sewage treatment plant was introduced in Jungnangcheon in 1975, a number of treatment processes have been applied to sewage treatment in Korea. However, in the past, the treatment process to remove organic substances has been mainly used. However, in Korea, where most of the water is dependent on surface water, the construction of a dam for drinking water is essential. It is known that inflow of nutrients is a cause of eutrophication during the storage of surface water.

Therefore, as the interest in the nutrient removal process has increased in our country since the 1990s, the nutrient removal process has been experimentally operated in sewage treatment plants, and many studies are being conducted on this.

The nutrient removal process can be divided into the biological nutrient removal process which removes nutrients using the decomposition of microorganisms through anaerobic, aerobic, and anoxic conditions, and the nutrient removal process by chemical aggregation as already known. Sequencing Batch Reactor (SBR) during the biological nutrient removal process is a reactor capable of introducing and discharging wastewater in a single reactor, and continuously implementing anoxic conditions, anaerobic conditions, and aerobic conditions in a single reactor. SBR can be modified to allow several processes to occur continuously, also called Intermittent Reactor or Fill-and-Draw Reactor.

In fact, SBR was developed in the early 20th century, but it has not been put to practical use in the field of environment. SBR is a process that converts the spatial concept of activated sludge into the concept of time, and is generally operated in the following five steps.

(1) The fill stage is the wastewater flows into the reaction tank and comes into contact with microorganisms to start the biodegradation of organic substances and nutrients contained in the wastewater. Inflow methods include mixed inflow, mixed inflow, and aeration inflow.

(2) React step removes contaminants introduced from the inlet, and removes organic substances, nitrogen, and phosphorus by using a combination of aerobic, anoxic and anaerobic steps.

(3) The settle step is a step in which solid-liquid separation is performed in the reaction tank to separate the treated material and the microorganism as a precipitate.

(4) The draw step is to discharge the supernatant obtained from the solid-liquid separation without disturbing the precipitated sludge.

(5) Idle step is not necessary, but is applied when the sludge is discharged or using a plurality of reactors, it can increase the efficiency by various applications.

The removal of nutrients using SBR began in the 1980s, and the characteristics of biological removal were studied by Manning and Irvine. Therefore, the removal of nitrate and DO from the inlet is important. And control of anaerobic period is known to be important for increasing removal efficiency [Manning, J, F. and RC Irvine, (1985), The Biological Removal of Phosphorus in a Sequencing Batch Reactor, JWPCF , 67, pp.87- 94].

Barnard, Barnard, JL, (1975), Biological Nutrient Removal without Addition of Chemical, Water Research, 9, pp. 486-490, it has been suggested that nitrate reduces phosphorus removal, because nitrate reduces anaerobic stress in the reactor. When nitrate is introduced into the anaerobic tank, the phosphorus removal is reduced because the poly-p microorganism consumes the organic matter necessary for phosphorus removal by nitrate denitrification.

It is therefore an object of the present invention to provide a sewage treatment apparatus in which a continuous batch single reactor is combined with a precipitation aeration tank.

Another object of the present invention is to provide a sewage treatment method capable of more efficiently removing organic substances and nutrients in domestic sewage.

1 shows a process diagram of a sewage treatment method combining a continuous batch reactor and a contact aeration tank according to the present invention, wherein the storage tank and the intermediate sedimentation tank may optionally be included, and the conveying line may be a contact aeration tank or, if present, an intermediate sedimentation tank. From a continuous batch single reactor.

<Explanation of symbols for the main parts of the drawings>

1: Sewage Treatment Process Combining Continuous Batch Reactor and Contact Aeration Tank

2: reservoir

3: continuous batch single reactor

4: contact aeration tank

5: medium sedimentation tank

6: metering pump

7: metering pump timer

8, 14: air supply

9: air supply timer

10: mixer

11: mixer timer

12: Mixer Propeller

13, 16: diffuser

15: contact media

17: return pump

18: Return Pump Timer

19: Surplus Sludge Disposal

20: final runoff

21: return line

Sewage treatment apparatus of the present invention,

It has an inlet mounted at the bottom, a propeller connected to the mixer, a diffuser connected to the air supply unit, a waste outlet for discharging excess sludge, and an outlet mounted at the upper side, and sedimentation conditions for separating sewage by gravity, Continuous batch type with repeated application of inflow / outflow conditions, anoxic conditions for reducing nitrate nitrogen to nitrogen, anaerobic conditions in which denitrified microorganisms elute phosphorus, and aerobic conditions in which microbial growth occurs due to nitrification of nitrogen and excess intake of phosphorus Single reactor,

A contact aeration tank equipped with an upper inlet and an outlet, a diffuser and a contact medium with microorganisms attached thereto, and performing additional biological treatment on the sewage introduced from the continuous batch single reaction tank, and

Conveying line for returning the effluent from the contact aeration tank to the continuous batch single reactor

It includes.

The sewage treatment apparatus may optionally further include a storage tank for storing sewage.

In addition, the sewage treatment apparatus, optionally, the sediment slurry outlet connected to the conveying line and the supernatant liquid outlet mounted on the upper portion, and may further include an intermediate sedimentation tank for separating the inflow water from the contact aeration tank by gravity.

In addition, the sewage treatment method using the sewage treatment apparatus of the present invention,

i) (a) sedimentation step of separating the influent sewage into the first sedimentation sludge layer and the first supernatant containing microorganisms and the object to be treated by gravity, (b) sewage to the first sedimentation sludge layer through the inlet of the lower part of the reactor Inflow and outflow step of uniformly flowing the first supernatant in an amount corresponding to the inflow amount through the outlet of the upper layer, and (c) activating the contact of the nitric acid nitrogen (NOx-N) in the inflow sewage with the denitrifying microorganism. Oxygen-free step of reducing to nitrogen (N ₂ ) through, (d) Anaerobic step of eluting phosphorus from the denitrification microorganisms present in the sewage via the anoxic step, and (e) Supplying air to the batch reactor, organic material Batch Single Reaction for the Nitrification of Nitrogen and Proliferation of Phosphorus-Ingested Microorganisms, and the Repeated Aerobic Step of Discarding Phosphorus-Ingested Microorganisms Joe steps,

(ii) a contact aeration tank step for further biological treatment of the to-be-processed material still present in the effluent from the continuous batch single reactor by the microorganisms attached to the air supply and contact media;

(iii) returning the effluent from the contact aeration tank to the continuous batch single reactor

It includes.

The sewage treatment method may optionally use a sewage treatment apparatus further including a storage tank.

In addition, the sewage treatment method, optionally, (ii) separating the effluent from the contact aeration tank step into a second precipitate slurry and a second supernatant containing desorbed microorganisms and the object, and the second supernatant is discharged It may further comprise a settling tank step.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and examples.

Referring to FIG. 1, the sewage treatment apparatus 1 of the present invention is largely divided into a storage tank 2, a continuous batch reaction tank 3, a contact aeration tank 4, an intermediate sedimentation tank 5, and a conveying line 21. At this time, the storage tank (2) and the intermediate settling tank (5) may optionally include.

In the case of sewage to be treated, fluctuations in flow rate and water quality are severe with time, and the storage tank 2 serves to uniformize such fluctuations in the sewage and to store inflow water flowing into the batch reactor.

The continuous batch reactor 3 simultaneously removes organic substances and nutrients by stepwisely setting anoxic conditions, anaerobic conditions, and aerobic conditions required for biological nutrient removal using a timer.

The contact aeration tank 4 serves to secure stable effluent water quality by removing untreated organic matter and suspended matter remaining in the firstly processed object.

The intermediate sedimentation tank 5 separates the effluent from the contact aeration tank stage into a sedimentation slurry and a supernatant.

The conveying line 21 conveys the precipitation slurry which came out of the intermediate precipitation tank to a continuous batch reactor again.

The role of each reactor and the situation in the reactor of the sewage treatment apparatus 1 of this invention are demonstrated in detail as follows.

In the case of forming the precipitation step in the continuous batch single reactor 3, the mixer 10 and the air supply device 8 are not driven, and the sludge containing the microorganisms and the object to be processed in the continuous batch single reactor 3 is Precipitation by gravity causes solid-liquid separation of the first settling sludge and the first supernatant. At this time, the first settling sludge is evenly deposited on the bottom in the reaction tank 3 to form a sludge layer, and the excess sludge is discharged at the same time (19).

After the precipitation step, by operating the metering pump (6) using the metering pump timer (7) flows the domestic sewage in the reservoir (2) into the reaction tank (3), the influent sewage into the sludge layer at the bottom of the reactor (3) Allow it to flow evenly. The sewage flowing into the sludge layer is separated into the first precipitate slurry and the first supernatant again, when the amount of the first supernatant corresponding to the amount of sewage flowing in reaches the outlet of the upper part of the batch reactor (3). Naturally out through the outlet.

After the inflow / outflow step, an anoxic step is formed in the reactor 3. The anoxic stage in the reactor 3 after the sewage inflow is completed, actively agitates the nitric acid nitrogen (NOx-N) in the influent sewage through the agitation of the propeller 12 by the mixer timer 11 and the mixer 10. By contacting, the nitrate nitrogen is reduced to nitrite nitrogen, the nitrite nitrogen is respectively reduced to nitrogen (N ₂ ) gas, and released into the atmosphere to remove nitrogen from the sewage.

When NOx-N is consumed by the denitrification microorganism in the anaerobic stage, it is converted to the anaerobic stage. That is, in the anaerobic stage, organic substances contained in the introduced sewage are converted into acetate and other fermented acids and accumulated in the cells of the microorganism, and poly-phosphorus (PHB; poly-β-) accumulated in the microorganism cells in the anaerobic state. Hydroxybutyrate is released to microorganisms in the form of ortho-phosphates by hydrolysis, resulting in microorganisms that are deficient in phosphorus. In this anaerobic phase, because the microorganisms are in a phosphorus-deficient state, they consume much more phosphorus than in the aerobic state where oxygen is supplied, and the phosphorus in the sewage is removed by removing the excess phosphorus-inducing microorganisms. You can do it.

Subsequently, the air supply timer 9 and the air supply device 8 are operated to supply oxygen through the diffuser 13 installed in the reactor 3, and at this time, the mixer 10 located above the reactor 3. It is also operated together to ensure that oxygen is smoothly supplied to the microorganisms in the reaction tank (3). When air is supplied, the reactor 3 is switched to the aerobic stage. In the aerobic phase, an aerobic microorganism primarily oxidizes organic matter in the treated sewage, and nitrification occurs in which ammonia is oxidized to nitrite nitrogen and nitrate nitrogen. In addition, PHB accumulated in the microorganism in the anaerobic stage is oxidized to acetate to be used as an energy source for the growth of microorganisms, the microorganism becomes a microorganism containing a large amount of phosphorus by luxury uptake (phosphorus uptake). Biological removal is achieved by discarding (19) microorganisms containing more phosphorus than ordinary microorganisms.

By forming the sedimentation step following the aerobic step again, the primary biological removal process of sewage is carried out in a continuous batch reactor 3 in which anaerobic conditions, anaerobic conditions, aerobic conditions are repeated.

On the other hand, the first supernatant flowing out at the same time as the inflow of sewage in the continuous batch reactor (3) flows into the contact aeration tank (4). The workpieces introduced into the contact aeration tank 4 are secondarily biologically treated using oxygen continuously supplied from the air supply device 14 through the diffuser 16. The workpiece to be introduced into the contact aeration tank 4 contains a small amount of suspended solids and organic matter not precipitated in the continuous batch reactor 3. The contact aeration tank 4 is provided with a contact medium 15 which has a microorganism attached at a constant concentration and has excellent buffering effect against load variation, thereby improving the efficiency of secondary biological treatment.

The workpiece subjected to the contact aeration tank 4 is returned to the continuous batch single reactor 3 via the transfer line 21 by the transfer pump timer 18 and the transfer pump 17, or, if necessary, an intermediate settling tank. (5) flows in. In the intermediate sedimentation tank (5), the influent from the contact aeration tank (4) is separated into solids by gravity to the second precipitate slurry containing the to-be-processed object and microorganism and the second supernatant to further improve the quality of the final effluent. 5) The second settling sludge settled at the bottom is likewise returned to the continuous batch single reactor 3 via the conveying line 21. Conveying takes place at the same time as the raw water is introduced.

<Example>

As shown in FIG. 1, sewage was treated using a sewage treatment apparatus in which a continuous batch single reaction tank and a contact aeration tank were combined. The sewage treatment apparatus was built on a laboratory scale using acrylic materials. The capacity, specifications, and specifications of the main apparatus used in this experiment are shown in Table 1 below.

Reactor and device standard Remarks Continuous Batch Reactor Tank Aeration Tank Medium Sedimentation Tank pH Meter Transfer Pump Mixer Blower Contact Media 5.0 L (diameter = 14.5 cm, H = 28.6 cm) 0.8 L (L = 10 cm, B = 8 cm, H = 10 cm) 0.5 L (diameter = 8 cm, H = 6 cm) Orion 250A master-flex ( Master-flex) pump panasonic m6ga30m korea dakasuki SPP-200GJ-H plate type media Cylindrical, sewage sludge spherical cone, hopper inclined at 60 degrees pH, temperature measurement 2 head 60 rpm 40 L / min Capacity: Polyurethane

Among various apparatuses used in the experiment, a pH meter was used to measure pH and ORP (Oxidation Reduction Potential) according to each condition of the continuous batch reactor, and the blower used air at the aerobic condition of the continuous batch reactor. A timer was used to feed. The raw water supply was uniformly introduced by using a transfer pump, and the movement of the sewage, which is an object to be processed in the continuous batch reactor, was arranged at the height of the contact aeration tank so as to be transferred under natural flow. The sewage used in the experiment was collected directly from the apartment manhole, which was a mixed discharge of domestic sewage and manure. The experimental results are shown in Table 2 below.

division CODcr BOD TSS TKN / NH ₃ NO ₃ -N T-P enemy 595 274 305 61/41 0 6.3 Batch Reactor Effluent 40 7.5 5.7 3.4 / 3.2 13 1.9 Final runoff 30 5.6 3.4 2.8 / 2.7 12 1.8 -Chemical Oxygen Demand (CODcr): Chemical Oxygen Demand (Use Cr as Oxidizer)-Biological Oxygen Demand (BOD): Biological Oxygen Demand-Total Suspended Solids (TSS): Total Suspended Solids-TjN (Kjeldahl Nitrogen): Kjeldahl The amount of nitrogen in the wastewater analyzed by the method-NH ₃ : ammonia nitrogen-NO ₃ -N: nitrate nitrogen-TP: total phosphorus-all values are in mg / L

The experimental results are average during the operation period, and the secondary treatment in the contact aeration tank was more effective for the stable removal of organic and suspended matter than the nutrient removal. The BOD content in the final effluent was 5.6 mg / L, the removal efficiency of T-N was 75.7% and the removal efficiency of phosphorus was 71.4%, which was very good.

From the above results, it was confirmed that when the sewage treatment was performed using a sewage treatment apparatus combining the continuous batch reactor and the contact aeration of the present invention, the removal efficiency of organic substances and nutrients in the sewage was very excellent.

According to the present invention, by treating the sewage using a sewage treatment apparatus in which a continuous batch single reaction tank and a contact aeration tank are combined, it is possible to greatly improve the efficiency of removing organic substances and nutrients and the economic efficiency of the sewage treatment process.

Claims (6)

It has an inlet mounted at the bottom, a propeller connected to the mixer, a diffuser connected to the air supply unit, a waste outlet for discharging excess sludge, and an outlet mounted at the upper side, and sedimentation conditions for separating sewage by gravity, Continuous batch type with repeated application of inflow / outflow conditions, anoxic conditions for reducing nitrate nitrogen to nitrogen, anaerobic conditions in which denitrified microorganisms elute phosphorus, and aerobic conditions in which microbial growth occurs due to nitrification of nitrogen and excess intake of phosphorus Single reactor, A contact aeration tank equipped with an upper inlet and an outlet, a diffuser and a contact medium with microorganisms attached thereto, and performing additional biological treatment on the sewage introduced from the continuous batch single reaction tank, and Conveying line for returning the effluent from the contact aeration tank to the continuous batch single reactor Sewage treatment device comprising a. The sewage treatment apparatus according to claim 1, further comprising a storage tank for storing sewage. The sewage treatment apparatus according to claim 1, further comprising a sediment slurry outlet connected to a conveying line and a supernatant liquid outlet mounted on the upper portion, and further comprising an intermediate sedimentation tank separating the inflow water from the contact aeration tank by gravity. (i) a sedimentation step of (a) separating the influent sewage into the first sedimentation sludge layer and the first supernatant containing microorganisms and to-be-treated by gravity, and (b) the first sedimentation sludge layer through the inlet of the lower part of the reactor. An inflow / outflow step in which the first supernatant in an amount corresponding to this inflow is uniformly introduced at the same time as the inflow of sewage, and (c) the contact with the denitrifying microorganisms of nitrate nitrogen (NOx-N) in the inflow sewage. An anoxic step of reducing to nitrogen (N ₂ ) through activation, (d) an anaerobic step of eluting phosphorus from denitrifying microorganisms present in sewage via the anoxic step, and (e) supplying air to a batch reactor, A continuous batch single-stage process that sequentially performs repeated aerobic steps to provide nitrification of nitrogen using the substance and propagation of over-phosphorus-induced microorganisms, while at the same time discarding microorganisms ingesting excess phosphorus. And crude steps, (ii) a contact aeration tank step for further biological treatment of the workpiece still present in the effluent from the continuous batch single reactor by the microorganisms attached to the air supply and contact media; (iii) returning the effluent from the contact aeration tank to the continuous batch single reactor The sewage treatment method using the sewage treatment apparatus of Claim 1 containing a. The sewage treatment method according to claim 4, wherein the sewage treatment apparatus further includes a storage tank. The intermediate settling tank according to claim 4, further comprising: (ii) separating the effluent from the contact aeration tank step into a second precipitation slurry and a second supernatant containing desorbed microorganisms and to-be-processed, and the second supernatant is effluent. Sewage treatment method including.