KR20010068370A - A removal method of organics and nitrogen compounds of wastewater using sequence batch reactor - Google Patents

Abstract

PURPOSE: Provided is a method for removing organic matter and nitrogen compound in sewage/wastewater using a continuous flow sequencing batch reactor. The sequencing batch reactor proceeds to fill, reaction, settle, draw and idle. CONSTITUTION: The method proceeds to the following steps: idling sewage/wastewater to conduct the oxidation of organic matter; circulating clarified water (from the former step) into the lower part of sludge layer in a sequencing batch reactor (2) through a pipe for influent wastewater by an internal circulation pump (3); at the same time or in order, oxidizing organic matter and nitrifying nitrogen compounds by aeration; idling secondary influent sewage/wastewater with no aeration; and circulating the clarified water (from the former step) into the lower part of sludge layer in the reactor (2) through a pipe for influent wastewater and then denitrifying nitrified compounds.

Description

A REMOVAL METHOD OF ORGANICS AND NITROGEN COMPOUNDS OF WASTEWATER USING SEQUENCE BATCH REACTOR}

The present invention relates to a method for removing organic matter and nitrogen compounds in wastewater / wastewater using a continuous batch reactor, and more specifically, nitrogen as the organic material is removed by a method of promoting the oxidation of organic matter in a continuous batch reactor. An improved method is to promote the oxidation of organic compounds by accelerating the oxidation of the compounds and then to effectively remove both organic and nitrogen compounds from the waste water / waste water by promoting denitrification under perfect anaerobic conditions.

At present, it is possible to reduce the impact of the high concentration wastewater in the activated sludge process and to use the fully mixed activated sludge process which is easy to operate.

However, since the process has a relatively low treatment efficiency, various biological treatment processes such as the pure oxygen activated sludge method and the deep aeration method have been developed and applied in recent years. Part of the research with great interest is the continuous batch reaction process.

Since the continuous batch reaction process is easy to control aerobic or anaerobic conditions, and easy to automate operation, a method that can be applied to a process for removing organic matter and nitrogen in sewage is under development.

The structure of the continuous ash reactor will be described with reference to the schematic diagram shown in FIG. 1, and about 3000 mg / L of mixed liquor suspended solids (MLSS) of activated sludge in a circular or rectangular reactor 2 having a conical or triangular pyramid shape at the lower end is described. Put in concentration and incubate for a certain time.

The inflow and outflow of sewage or waste water are driven by a pump, respectively, of which the inflow pump 1 is operated by a water level regulator 4 connected to the reactor 2, and the outflow pump 7 is a timer 8. It is operated by. At this time, the outflow amount is preferably the same as the inflow amount, but should be controlled by using the timer 8 because at least 66 hours of the volume in the reactor must be discharged within at least 1 hour 30 minutes.

In addition, an acidizer device 5 for supplying oxygen to the inflow water introduced into the reactor 2 is connected to the lower part of the reactor 2, which also uses a timer (6) for each unit of time Repeat the operation and pause.

When the continuous batch reactor is used, unit processes of inflow, reaction, sediment, draw, and idle of wastewater are continuously generated according to a predetermined time sequence. It is not necessary to use a secondary sedimentation basin, it is easy to control the filamentous bacteria of the sludge, and is easy to install, which is very desirable in terms of wastewater management.

However, since the volume of the reactor is determined according to the oxidation rate of the organic material or nitrogen compound, the rapid ashing of the materials is an important factor in improving the process.

In addition, in order to remove nitrogen compounds in the wastewater, it is important to set up the precipitation process in the continuous batch reaction process under perfect anaerobic conditions.

Accordingly, an object of the present invention is to provide a method for rapidly oxidizing an organic material while maximizing the advantages of the conventional continuous batch reactor.

Another object of the present invention is to provide a method for effectively removing nitrogen compounds by promoting perfect anaerobic conditions during a continuous batch reaction.

1 is a schematic diagram illustrating a continuous batch reactor used in the process of the present invention,

2 is a graph showing a change in ammonia nitrogen concentration in the sewage according to the pH change during operation in the conventional method,

3 is a graph showing a change in COD concentration in the sewage according to the pH change during operation in the conventional method,

4 is a graph showing the ammonia nitrogen concentration in the sewage during internal circulation according to the present invention,

5 is a graph showing a change in the concentration of nitrite and nitrate ions in sewage during internal circulation according to the present invention,

6 is a graph showing a change in the concentration of COD in sewage during internal circulation according to the present invention,

7 is a graph showing a change in denitrification concentration in sewage when 10 inflow water of the primary inflow is recirculated while internally circulating according to the present invention;

8 is a graph showing a change in denitrification concentration in sewage when 5 inflows of primary inflows are recirculated while internally circulating according to the present invention;

9 is a graph showing the change in the COD concentration when the second inflow of the sewage to be treated after the internal circulation according to the present invention.

* Description of Major Symbols in Drawings *

1 ... inlet pump 2 ... sequence batch reactor

3 ... Internal circulation pump 4 ... Water level regulator 5 ... Air diffuser

6,8 ... Timer 7 ... Spill Pump

According to the invention,

In the method of treating the waste / waste water by introducing the waste / waste water into the continuous ash reactor through the waste / waste water inlet pipe, then aerated and precipitated,

Leaving the introduced sewage / wastewater to induce oxidation of organic matter present in the influent;

Circulating the supernatant and new waste water to the lower part of the sludge layer in the reactor by circulating the supernatant obtained after the inflow of water into the inlet pipe by an internal circulation pump installed in the inner circulation path connecting the reactor and the inlet pipe;

Simultaneously or sequentially aeration to promote complete oxidation of the organic matter and nitrification of the nitrogen compound;

Blocking aeration and introducing only fresh sewage / waste water secondly and then leaving it; And

Circulating the supernatant obtained after the inflow of water into the inlet pipe by the internal circulation pump to circulate the supernatant and the new wastewater to the lower part of the sludge layer in the reaction tank to denitrate the nitrified compound. A method of removing organic matter and nitrogen compounds in wastewater is provided.

Hereinafter, the present invention will be described in detail with reference to the continuous ash reactor 2 shown in FIG.

The present inventors have found that, by internally circulating the treatment liquid in the continuous batch reactor and refeeding the influent, it is possible to promote oxidation of organic matter and to promote denitrification in a perfect anaerobic state, and thus, the present invention has been completed.

In the present invention, the wastewater to be treated into the continuous ash reactor 2 is introduced at a relatively high flow rate. At this time, oxygen is not supplied.

In the present invention, the inflow time varies depending on the quality of the wastewater / wastewater to be treated. However, when the wastewater is treated with 500 ppm of COD and 40 ppm of NH ₄ ⁺ -N, the inflow time is preferably introduced within 15 of the reaction time. That is, it can be introduced for 45 minutes when the total reaction time is 12 hours.

Inflow is complete and stopped to induce organic oxidation. The stop time is directly related to the concentration of the organic material. If the concentration of the organic material is low, the stop time may be reduced, and when the stop time is high, the stop time may be increased. The stop time also depends on the water quality of the wastewater to be treated, but when treating the sewage water of 500 ppm COD and 40 ppm NH ₄ ⁺ -N it is good to stop about 25 of the reaction time. That is, it can be stopped for 3 hours when the total reaction time is 12 hours.

Then, the supernatant of the reactor 2 is circulated with the inlet water to the lower end of the sludge layer in the reactor by using the internal circulation pump 3.

The internal circulation is made by using an internal circulation path installed to inlet the reactor supernatant to the lower end by installing a suction port at a position corresponding to 40 of the reactor height from the lower end of the reactor, and the higher the circulation flow rate, the higher the organic oxidation rate. It is preferable that it is 90 or more of inflows.

Such internal circulation can be continuously circulated regardless of the aeration or non-aeration conditions. However, during the aeration process, the sludge is not necessarily circulated, but a sludge layer is formed during the non-aeration. do.

Therefore, the aeration can be performed simultaneously with the internal circulation or sequentially. At this time, the aeration condition is to operate the aerator device 5 and to maintain the dissolved oxygen amount in the reaction tank more than 2mg / ℓ. When aeration is supplied and oxygen is supplied to the reaction tank 2, the activated sludge is uniformly formed. Therefore, organic matter in the sewage or wastewater to be treated reacts with the sludge and is converted into inorganic carbon such as carbon dioxide, and nitrogen compounds are nitrous acid and nitric acid. Oxidized to ions.

At this time, if the dissolved oxygen amount is less than 2mg / ℓ because the microorganism is limited to oxidize organic matter or oxidize nitrogen is not preferable. Therefore, if the dissolved oxygen is lower than this, the amount of aeration should be increased to increase the supply of oxygen to the wastewater or wastewater.

Through this internal circulation, the sludge layer precipitated during the non-aeration in the reactor 2 can further accelerate the oxidation and reduction.

This internal circulation and aeration causes the organics to be oxidized by microorganisms in the sludge layer to be oxidized or in suspended sludge and then to nitrification. This is represented by the following equation.

Organic + xH ₂ O → YCO ₂ + microbial + Ze ^- (organic oxide)

^{_{NH 4 + + 3H 2 O →}} NO 3 - + 10H + + 8e - ( nitrification)

_{^{O 2 + 4H + + 4e -}} → 2H 2 O ( reduction)

In addition, the pH in the reactor 2 during the reaction is preferably controlled to be higher than 7 and lower than 9, preferably 7.5 in order not to reduce the activity of the microorganisms.

Then turn off the aerator. The aeration time varies depending on the inflow flow rate, and it is sufficient that all of the nitrogen compounds in the wastewater / wastewater to be treated can be converted into nitrate ions. The aeration time also depends on the water quality of the waste water to be treated, but when the water quality is treated with 500 ppm COD and 40 ppm NH ₄ ⁺ -N 40 aeration of the entire process and then turn off the power. That is, when the total reaction time is 12 hours, it can be aerated for 4 hours 48 minutes to 5 hours 24 minutes.

After the aeration is cut off, the inflow pump (1) is operated to resupply 6 to 10 of the flow rate at which the inflow source water was first supplied (secondary inflow of raw water). At this time, if the second inflow is 6 or less, the nitrate ions are not removed and remain in the reaction tank. This also depends on the quality of the sewage / waste water to be treated, but in the case of treating sewage with water quality of 500 ppm COD and 40 ppm NH ₄ ⁺ -N, the second inflow time is preferably within 10 minutes when the total reaction is 12 hours. .

By blocking the aeration in this way to promote the state in the reactor to an anoxic (anaerobic) state and then to the inflow of the second inflow, to provide a carbon source for denitrifying nitrite and nitrate ions. If this is represented by the reaction scheme is the same as the above formula 1.

Then, the supernatant in the reaction tank 2 is circulated to the lower end of the sludge layer, and the nitrate and nitrite ions which are denitrified are reduced to nitrogen gas. This is represented by the following scheme.

_{^{2NO 3 - + 12H + + 10e}} - → N 2 + 6H 2 O ( reduction)

After stopping the aeration, stop for as long as necessary to denitrate the nitrate ions and then run the outflow pump to discharge the treated sewage or wastewater in the reactor.

The stop time may vary depending on the inflow flow rate, but the denitrification reaction is almost completed in about 2 hours, and about 3 hours is sufficient. For example, in the case of treating wastewater having 500 ppm of COD and 40 ppm of NH ₄ ⁺ -N, it is preferable to stop for about 25 to 30 during the whole process. That is, when the total reaction time is 12 hours, it can be flowed out for 3 hours to 3 hours 36 minutes.

At this time, the outflow flow rate is most preferably the same as the inflow flow rate as described above, but may be a flow rate that can outflow 66 of the waste / waste water volume in the reaction tank within 1 hour and 30 minutes. More preferably, about 10 to 20% of the total reaction time is flowed out.

In 20 or more, the outflow time is too long, and in less than 10, since the outflowing pump becomes large, the power ratio is not preferable. For example, in the case of treating sewage with 500 ppm of COD and 40 ppm of NH ₄ ⁺ -N, the total reaction time may be 1 hour 12 minutes to 2 hours 24 minutes when the reaction time is 12 hours.

According to the present invention, the organic matter is oxidized by using the sludge layer precipitated in the reactor by inflow → internal circulation → aeration reaction → aeration blocking → secondary inflow → internal circulation → flowing out of the wastewater to be treated in the continuous ash reactor. Nitrogen compounds are nitrified and denitrified to effectively remove organic matter and nitrogen compounds from sewage as well as wastewater.

Hereinafter, embodiments of the present invention will be described in detail.

<Example>

The following examples are to determine the removal efficiency of organic substances and nitrogen compounds contained in the waste water or sewage by the method according to the present invention.

Continuous ash reactor (2) used in the following examples, as shown in Figure 1, based on a rectangular reactor (2) of 40cm × 40cm × 60cm from the top 30cm from the bottom to the square pyramid shape, the inside The suction port of the return line for circulation was located at the corner of the bottom 40 cm from the top of the reactor.

Comparative Example 1

The correlation between pH and ammonia nitrogen concentration during operation was investigated.

The inflow water was introduced into the reactor 2 through the inflow pump 1 at a flow rate of 30.8 L / h for 50 minutes, and then the flow rate was kept constant through the water level regulator 4. Oxygen was supplied at a flow rate of 22.5 m ³ / m ² · h through the acidizer 5 at the bottom of the reactor, and the concentration of dissolved oxygen was maintained to be about 4-6 mg / l during the aeration.

In addition, the outflow pump (7) was adjusted to 17.1 l / h so that all the incoming raw water can flow out within 1 hour 30 minutes.

The operating conditions of the continuous batch reactor used in the present invention are shown in Table 1 below.

inflow stop Aeration reaction stop Outflow Reaction time 50 minutes 70 minutes 300 minutes 210 minutes 90 minutes Diffuser (5) block block work block block Inflow pump (1) work block block block block Outflow Pump (7) block block block block work

Then, while adjusting the pH of the reactor to 5.5, 6.5, 7.5, the concentration of ammonia nitrogen in the influent was observed, and the results are shown in FIG. The concentration of ammonia nitrogen in the influent was 40 mg / l.

As can be seen in Figure 2 the removal rate of ammonia at pH 5.5, 6.5, 7.5 was 30, 42, 57 respectively. Therefore, as the pH increased, it was confirmed that a lot of ammonia was removed.

Comparative Example 2

The correlation between pH and COD during operation was investigated.

The same operation as in Example 1 was repeated, and the COD change was measured under the same pH conditions, and the results are shown in FIG. 3. The COD concentration in the influent was 500 mg / l.

As can be seen in Figure 3, at pH 5.5, 6.5, 7.5 it appeared as 70, 78, 84, respectively. Therefore, as the pH was increased, the removal rate of the organic material was confirmed to be improved.

<Example 1>

In this embodiment, the concentration change of ammonia nitrogen according to the internal circulation in the continuous ash reactor is examined.

The same operation conditions are repeated except that the internal circulation is performed for each of the inflow, stop, reaction, stop, and outflow processes as shown in Table 2 among the operating conditions of the continuous ash reactor 2 shown in Table 1 of Comparative Example 1. It was. At this time, the pH of the reactor was maintained at 7.5.

inflow stop Aeration reaction stop Outflow Reaction time 50 minutes 70 minutes 300 minutes 210 minutes 90 minutes Diffuser (5) block block work block block Inflow pump (1) work block block block block Outflow Pump (7) block block block block work Internal Circulation Pump (3) 쟉 work Activate / Block work Activate / Block

The internal circulation rate was adjusted to 33 (10.2 L / hr), 66 (20.3 L / hr), 90 (27.7 L / hr) compared to the inflow rate of raw water (30.8 L / h), and the oxidation rate of ammonia was measured. Is shown in FIG. 4.

As can be seen from Figure 4, when the internal circulation rate is adjusted to 33, 66, 90, the oxidation rate of ammonia increased to 62.5, 80, 90, respectively. Therefore, it was confirmed that the oxidation reaction in which ammonia is converted to nitrous acid and nitrate ions is accelerated by forcibly circulating the supernatant in the reactor to the bottom of the sludge layer in the reactor.

In addition, the concentrations of nitrite ions and nitrate ions in the reaction tank were measured at the respective internal circulation rates, and the results are shown in FIG. 5. As the internal circulation rate increased, the production of nitrite and nitrate ions increased.

As a result, the oxidation rate of ammonia was 57 (see Comparative Example 1) when not internally recycled in the reaction tank, whereas the oxidation rate was increased to 90 when the internal circulation rate 90 was applied. Therefore, it can be inferred that the concentration of nitrous acid and nitrate ions produced in the reaction tank increases by internal circulation.

<Example 2>

In this embodiment, the effect of the COD improvement according to the internal circulation in the continuous batch reactor.

The COD oxidation rate was measured under each internal circulation rate of Example 1, and the results are shown in FIG. 6. As can be seen in Figure 6, the COD oxidation rate increased to 70 (internal circulation rate 33), 92 (internal circulation rate 66, 92).

That is, in Comparative Example 2 without internal circulation, the COD oxidation rate was 84, whereas in the case of internal circulation, the COD oxidation rate was improved to 92. As a result, the COD oxidation rate was improved as the internal circulation rate in the reaction tank was increased.

<Example 3>

In this example, the relationship between the inflow rate and the concentration distribution of the nitrogen compound in the case of the internal circulation and the second inflow of the raw water was investigated.

Raw water is added to the reactor 2 after the aeration in a state in which the inlet pump is operated for 5 minutes in the second stop step among the operating conditions of the continuous ash reactor 2 shown in Example 1 and the internal circulation rate is adjusted to 90. The concentration distribution of the nitrogen compound in the reaction vessel at the time of supplying 10 to the first inflow to the secondary inflow was shown in Figure 7 the results.

In addition, in the case where the raw water is supplied to the reactor 2 at a second rate of 5 with the internal circulation rate adjusted to 90, the concentration distribution of nitrogen compounds in the reactor is examined, and the results are shown in FIG. 8. .

As can be seen in Figure 7, it was confirmed that both the reaction of ammonia is oxidized to nitrite and nitrate ions and the reaction to reduce the nitrite and nitrate ions to nitrogen is performed well. In contrast, in FIG. 8, it was confirmed that all of the nitrate ions could not be removed and remained slightly in the reactor.

Therefore, when raw water is introduced secondly when the oxidation of ammonia is completed through the internal circulation in the reaction tank, these raw waters replenish organic matter for denitrification and consume the remaining dissolved oxygen. It can be inferred that it can be removed completely. In addition, the secondary inflow was found to be effective 6 to 10 compared to the primary inflow.

<Example 4>

In this embodiment, the COD change in the case of the second inflow of raw water while internal circulation is investigated.

The change of COD was measured under the same conditions as in Example 3 except that the inflow pump was operated for 5 minutes in the second stop step among the operating conditions of the continuous ash reactor 2 shown in Example 1, and The results are shown in FIG.

In this case, since the removal rate is similar to the result of Example 2 (FIG. 6) in which there was no secondary inflow although there was a secondary inflow, Can be inferred.

As a result, the concentration of 500 mg / l of COD and 40 mg / l of nitrogen compound in raw water is reduced to 40 mg / l and 5 mg / l, respectively, according to the method of the present invention. Compared with / L, the concentration of nitrogen compound 18mg / L, it was confirmed that the oxidation, nitrification and denitrification of the organic matter is much improved by the internal circulation and the second inflow of raw water while using a continuous batch reactor.

According to the above, by circulating the supernatant in the continuous batch reactor and inflowing the secondary influent, the microorganism of the sludge and the organic matter in the influent can be activated to promote the oxidation of the organic matter and complete anaerobic treatment without any additional treatment. Under conditions, denitrification can be encouraged, and further treatment facilities can be simplified.

Claims (4)

In the method of treating the waste / waste water by introducing the waste / waste water into the continuous ash reactor through the waste / waste water inlet pipe, then aerated and precipitated, Leaving the introduced sewage / wastewater to induce oxidation of organic matter present in the influent; Circulating the supernatant and new waste water to the lower part of the sludge layer in the reactor by circulating the supernatant obtained after the inflow of water into the inlet pipe by an internal circulation pump installed in the inner circulation path connecting the reactor and the inlet pipe; Simultaneously or sequentially aeration to promote complete oxidation of the organic matter and nitrification of the nitrogen compound; Blocking aeration and introducing only fresh sewage / waste water secondly and then leaving it; And Circulating the supernatant obtained after the inflow of water into the inlet pipe by the internal circulation pump to circulate the supernatant and the new wastewater to the lower part of the sludge layer in the reaction tank to denitrate the nitrified compound. How to Remove Organics and Nitrogen Compounds in Wastewater The method of claim 1, wherein the aeration condition is characterized in that the amount of dissolved oxygen in the reactor to maintain more than 2ml / l The method of claim 1, wherein the pH of the reaction tank is maintained at 7 to 9 during the aeration. The method of claim 1, wherein the inflow of the secondary inflow is 6 to 10 based on the volume of the primary inflow