KR102169383B1 - Sludge reduction and its sewage treatment method - Google Patents

Abstract

Disclosed is a method for reducing sludge and treating sewage using its by-products. The sewage treatment method of the present invention includes (a) the first step in which the sewage flowing through the screen from the sewage pipe is introduced into the flow storage tank and the second step of detecting the carbon source concentration and nitrogen concentration of the influent water in the flow storage tank, and the inflow flow rate based on the nitrogen concentration. In the process of reducing solids through a hydrolysis step for sludge collected in the sedimentation tank, by comprising three steps of calculating the inflow, four steps of introducing the calculated inflow flow into the denitrification tank, performing the denitrification process, and a discharge step. It has the effect of providing a technology that utilizes the produced organic material as a carbon source for advanced sewage treatment and uses it as an organic material and a method of operating biological treatment technology.

Description

Sludge reduction and sewage treatment method using its by-products{SLUDGE REDUCTION AND ITS SEWAGE TREATMENT METHOD}

The present invention relates to a device for reducing and solubilizing sludge collected in a sewage sludge sedimentation tank by thermal hydrolysis, and more specifically, to replace an external carbon source used to treat sewage flowing into the sewage treatment process at a low concentration C/N ratio. It is about the possible sludge reduction and the sewage treatment method using the by-products.

The technology for treating domestic sewage is based on biological treatment, including pre-treatment and post-treatment in order to maximize biological treatment including various microorganisms (bacteria, protozoa, fungus, gall bladder, algae). Processing.

To understand biologically the reduction of pollutants in sewage, the operating conditions must be different.

<Mechanism that occurs according to the presence or absence of air in biological treatment>

first. Microbial mechanism under aerobic conditions

Aerobic heterotrophic microorganisms use oxygen (O ₂ ) as an electron acceptor, and as a carbon source for electron donors and microorganisms, organic matter in wastewater is reduced. At this time, carbon dioxide (CO ₂ ) and water (H ₂ O) are produced as final products.

Aerobic autotrophic microorganisms are largely divided into three reactions.

1. There is a nitrification reaction in which ammonia acts as an electron donor and is oxidized in stages to change to nitrite nitrogen or nitrate nitrogen, and carbon dioxide (CO ₂ ) in water is used as the carbon source.

2. Iron oxidation in which ferrous iron (Fe(II)) acts as an electron donor and uses carbon dioxide (CO ₂ ) in the water system as a carbon source to finally convert it into ferric iron (Fe(III)). There is this.

3. Hydrogen sulfide (H2S), sulfur ions (S ⁰ ), thiosulfuric acid (S ₂ O ₃ ^2- ) act as electron donors and use carbon dioxide (CO ₂ ) as a carbon source to finalize sulfate ions (SO ₄ ^2- ). There is a sulfur oxidation process that is made into a substance.

In this case, the nitrification phenomenon is theoretically composed of two steps.

[Nitroso-bacteria]

^{_{2NH 4 + + 3O 2 ->}} 2NO 2 - + 4H + + 2H 2 O

[Nitro-bacteria]

^{_{2NO 2 - + O 2 ->}} 2NO 3 -

[Total oxidation reaction]

^{_{NH 4 + + 2O 2 ->}} NO 3 - + 2H + + H 2 O

In particular, in the case of the nitrification process, since nitrifying microorganisms oxidize ammonia existing in the water system only with nitrate nitrogen or nitrite nitrogen, there is no reduction compared to the introduced nitrogen.

Therefore, in addition to continuously supplying oxygen, it is necessary to block the supply of oxygen so that other electron acceptors can be used.

second. Microbial mechanism in anoxic conditions

Utilizing aerobic the organic material with an electron donor and carbon source similar to the conditions (Organic compounds), and the nitrate as an electron acceptor nitrogen (NO ₃ ^-) or nitrite (NO ₂ ^-) to utilize in the final product nitrogen gas (N ₂ ), carbon dioxide (CO ₂ ), and water are produced, and this mechanism is called denitrification or anoxic reaction.

At this time, in order for denitrification to proceed, there must be no oxygen concentration (DO) or low oxygen concentration (DO) in water, and nitrate nitrogen and nitrite nitrogen must exist. Therefore, in the process sequence, it is appropriate to place nitrite nitrogen or nitrate nitrogen generated after the aerobic tank in an oxygen-free tank so that the oxygen concentration naturally decreases.However, when the aerobic tank is in the front end, organic substances that can be used as electron donors are used by aerobic microorganisms. Because it is used, electron donors to be used for denitrification are insufficient.

Therefore, in order to solve this problem, a pre-denitrification process is mainly used in which the inflow water and the sewage circulating in the rear aerobic tank are mixed at a certain ratio and introduced into the denitrification tank, followed by nitrification.

Assuming that the domestic sewage is C ₁₀ H ₁₉ O ₃ N, the theoretical equation of the denitrification process for this is as follows.

_{C 10 H 19 O 3 N +} 10NO 3 - -> 5N 2 + 10CO 2 + 3H 2 O + NH 3 + 10OH -

However, due to the low C/N ratio, which is a characteristic of domestic sewage, sufficient electron donors are not injected, so it takes a long time for denitrification. To solve this problem, an additional carbon source is introduced to induce efficient denitrification. Typically, acetic acid or methanol is used as an external carbon source, and when used as such an external carbon source, it has the following equation.

The C/N (COD/TKN) ratio refers to the ratio between the organic matter and nitrogen concentration in the influent water, which has a great influence on the treatment efficiency of the nitrogen and phosphorus removal process in the aeration tank. Means rain.

Since nitrate nitrogen generated in the aeration tank affects phosphorus emission in the anaerobic tank, the COD/TKN ratio of the influent also has a great influence on the treatment efficiency of the nitrogen and phosphorus removal process.

[Methanol]

5CH ₃ OH + 6NO _{3 -> 3N 2 + 5CO 2 +} 7H 2 O + 6OH -

[Acetate]

^{_{5CH 3 COOH + 8NO 3 - -}} > 4N 2 + 10CO 2 + 6H 2 O + 8OH -

To replace these external carbon sources, the possibility of using organic waste is emerging. In the case of a sewage treatment plant, since it is based on biological treatment, organic matter in the water decreases and microorganisms proliferate. Therefore, in order to increase the dehydration efficiency of the proliferated microorganisms, a chemical agent similar to a coagulant is injected and the solid is separated through a dehydrator. Dewatered sludge is used as a vehicle for landfills, incineration plants, and cement auxiliary materials. However, in the case of landfill facilities, direct landfilling of sludges is prohibited due to lack of landfill capacity, and even if landfilled, since leachate is generated because it contains more than 80% moisture, additional water treatment facilities are required to treat them.

In the case of incineration, the water content must be lowered through pretreatment, and the sludge itself needs auxiliary fuel because the calorific value is low, and even if it is incinerated, air pollutants such as nitrogen and sulfur oxides are generated, so a process to reduce this is essential. .

If sewage sludge is treated and used as a carbon source, it is expected to reduce the total amount of sludge generated in the sewage treatment plant and improve the efficiency of advanced sewage treatment in the sewage treatment plant.

In the case of a small-scale sewage treatment plant, it is difficult to stably maintain the quality of the effluent water, and it is difficult to remove nutrients that are the cause of eutrophication.

In addition, stable sludge control is difficult, and sludge is discharged according to an increase in the inflow quantity.

KR Registered Utility Model Publication No. 20-0367638 (2004.11.03)

The present invention for solving this problem is to reduce sludge and a sewage treatment method using the by-products to provide a technology for utilizing organic matter as a carbon source for advanced sewage treatment and utilizing it as an organic material and a biological treatment technology operating method using the same. It aims to provide.

In addition, another object of the present invention is to provide a method for reducing and solubilizing sewage sludge collected in a sedimentation tank of a sewage treatment plant by using thermal hydrolysis to reduce and solubilize the sludge.

In addition, another object of the present invention is to provide a method for reducing sludge and treating sewage using the by-products, which can maintain the concentration of contaminants introduced into the denitrification tank within a specific range by mixing sewage and sludge circulated at the bottom of the settling tank. To do.

Another object of the present invention is to provide a method for reducing sludge and treating sewage using the by-products, which can effectively perform the function of stabilizing organic matter and nitrogen under optimal conditions by controlling the amount of additionally added thermal hydrolysis by-products. .

The sewage treatment method using the sludge reduction and the sewage treatment system utilizing the by-products of the present invention to solve these problems includes (a) step 1 in which the sewage passing through the screen from the sewage pipe flows into the flow storage tank and (b) the flow rate. The second step of detecting the carbon source concentration and the nitrogen concentration of the influent water in the storage tank, (c) the third step of calculating the inflow flow rate based on the nitrogen concentration, and (d) the fourth step of introducing the calculated inflow flow rate into the denitrification tank, ( It can be achieved by configuring to include e) a denitrification process performing step, and (f) a discharge step.

In addition, step (d) comprises a step of mixing the sludge containing nitrate nitrogen at the bottom of the flow storage tank and the aerobic tank and mixing the sludge containing nitrate nitrogen into the denitrification tank, and mixing the nitrogen concentration detected in the flow storage tank with the aerobic tank sludge. Dilution and, if the nitrogen concentration of the mixed denitrification tank influent is higher than the reference concentration, increasing the internal circulation amount of the aerobic tank to adjust the nitrogen concentration of the mixed inflow water to the reference concentration, and increasing the circulation amount, detection in the mixed inflow water If the determined nitrogen concentration does not exist within the reference concentration range, it may include a third step of determining to repeatedly perform the step of increasing the circulation amount.

In addition, the first step in which sewage is introduced into the batch-type bioreactor, and the second step in which the input sewage is adjusted to the standard concentration (15-20 mg-N/L) in the reaction tank based on the ammonia concentration to control the operating conditions, and in the bioreactor Step 3 of proceeding biological denitrification through stirring, step 4 of supplying air using a lower air diffuser when the concentration of nitrate nitrogen (NO3) and nitrite nitrogen (NO2) in the bioreactor is maintained below 1, the In the case where the ammonia concentration in the reaction tank is maintained at 0.5 mg-N/L or less, 5 steps of stopping stirring and air supply, and 6 steps of discharging the flow rate (1Q) introduced after a settling time of 30 minutes or more in the reaction tank are included. Make up.

Therefore, according to the sludge reduction and sewage treatment method using the by-products of the present invention, the sludge collected in the sedimentation tank reduces the solid content through the hydrolysis step, and the organic material produced in the decomposition process is utilized as a carbon source for advanced sewage treatment. There is an effect that can provide a technology used as an organic matter and a method of operating a biological treatment technology.

In addition, according to the sludge reduction and the sewage treatment method using the by-products of the present invention, there is an effect of reducing and solubilizing the sewage sludge collected in the sedimentation tank of the sewage treatment plant by using thermal hydrolysis.

In addition, according to the sludge reduction and the sewage treatment method using the by-products of the present invention, there is an effect of maintaining the concentration of pollutants introduced into the denitrification tank within a specific range by mixing the sewage and sludge circulated at the bottom of the settling tank.

And according to the sludge reduction and the sewage treatment method using the by-products of the present invention, it is possible to effectively perform the function of stabilizing organic matter and nitrogen under optimal conditions by controlling the amount of additionally added thermal hydrolysis by-products.

1 is a main configuration diagram of a biological sewage treatment system using sludge reduction and by-products according to an embodiment of the present invention,
2 is a table of nitrogen components, dissolved organic and inorganic carbon concentrations in effluent discharged when an external carbon source is not input in a sewage treatment apparatus having a linear denitrification structure as a result of an example,
FIG. 3 is a table of operation results of treated water discharged when the thermally hydrolyzed biological sludge is added to the denitrification tank based on the influent amount (1Q);
4 is a schematic configuration diagram of a single-phase batch reactor in addition to the reactor in which the biological denitrification and nitrification are separated,
5 is a table of changes in concentration varying with time when the thermally hydrolyzed sludge as a result of the Example in a batch reactor is added according to the inflow flow rate,
6 is a flow chart for explaining a biological sewage treatment method between the flow storage tank and the denitrification tank according to an embodiment of the present invention,
7 is a flow chart for explaining a biological sewage treatment method between a flow storage tank and an aerobic tank according to an embodiment of the present invention;
And
8 is a flowchart illustrating a biological sewage treatment method between a lower part of a settling tank and a denitrification tank according to an embodiment of the present invention.

Terms and words used in the present specification and claims are not limited to the usual or dictionary meanings, and the inventor is based on the principle that the concept of terms can be appropriately defined in order to explain his or her invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention.

Throughout the specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated. In addition, terms such as "... unit", "... group", "module", and "device" described in the specification mean a unit that processes at least one function or operation, which is implemented by a combination of hardware and/or software. Can be.

Throughout the specification, the term "and/or" is to be understood as including all possible combinations from one or more related items. For example, the meaning of “a first item, a second item and/or a third item” may be presented from two or more of the first, second or third items as well as the first, second or third item. It means a combination of all possible items.

Throughout the specification, the identification code (for example, a, b, c, ...) in each step is used for convenience of description, and the identification code does not limit the order of each step, and each step is It may occur differently from the specified order unless a specific order is clearly stated in the context. That is, each of the steps may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 is a schematic diagram of a biological sewage treatment system using sludge reduction and by-products according to an embodiment of the present invention.

As shown, the biological sewage treatment system of the present invention removes sand and impurities that do not decompose from sewage and controls the influent water flowing into the flow storage tank 20, the denitrification tank 30, the aerobic tank It comprises (40), a settling tank (50) and a thermohydrolysis reactor (60).

First, in the present invention, the supernatant in the nitrogen concentration in the influent is detected in the form of NH ₄ ⁺ -N concentration, and it will be expressed as the nitrogen concentration in the influent water.

Sewage generated in daily life is primarily collected in the flow storage tank 20 because the difference in concentration and generation amount of organic substances according to the generation time is shown.

The collected sewage is mixed at a constant concentration, and when the input amount is mixed at a constant flow rate and concentration, stable sewage treatment is possible.Therefore, a circulation pump or a stirring device may be provided in the flow storage tank 20 to form a condition for completely mixing. have.

Here, the circulation pump or other stirring device becomes a device for controlling the conditions of complete mixing of sewage.

In addition, the flow storage tank 20 may be provided with a carbon source concentration meter 22 and a nitrogen concentration meter 24.

The front end of the flow storage tank 20 may be provided with a screen 10 for removing solid substances such as sand and impurities that are not decomposed.

In particular, if impurities are not removed through the screen 10, the accumulation of inorganic matter in the subsequent process and inhibition of circulation pumping and stirring may occur.

In the operation of the sewage treatment system, controlling the inflow water through the removal of inorganic matter and impurities through the screen 10 can increase the efficiency of sewage treatment.

The denitrification tank 30 is configured to perform a biological denitrification process, and must be maintained in an appropriate range of conditions for denitrification.

Otherwise, the efficiency may fall outside the range that can be handled at the designed capacity.

For example, in a biological denitrification process, when the concentration of organic substances in water is low, the denitration rate is affected. Such a low concentration of organic substances does not end denitrification in a predetermined reaction tank, so that a nitrogen concentration above the reference concentration remains in the effluent after the nitrification process. This phenomenon often occurs especially in small-scale sewage treatment plants where process operation is difficult.

In order to prevent problems occurring in the denitrification process in advance, in this embodiment, the nitrogen concentration input from the flow storage tank 20 to the denitrification tank 30 is measured by a nitrogen concentration meter 24 and designed based on the measured value. In order to detect whether the thermal hydrolysis solution input in real time is appropriate, and the concentration of nitrate and nitrite nitrogen in the denitrification tank 30, and the ammonia concentration in the aerobic tank 40 to be described later is below a certain level and control the process. do.

To this end, the denitration tank 30 may include a stirring device 32, a nitrate nitrogen concentration detection unit 34, and an internal circulation path 36.

According to this proposal, it is possible to keep the quality of the effluent water constant after the biological sewage treatment process.

In addition, it is possible to reduce by-products generated in a sewage treatment plant through a method of utilizing biological sludge internally.

Biological denitrification is based on the use of an electron acceptor that replaces oxygen because oxygen cannot be used as an electron acceptor when operating in an oxygen-free condition that does not supply air in the activated sludge method.

The bacteria of nitrate instead of oxygen (NO ₃ ^-) use, and the nitrate is converted into nitrogen gas to reduce the nitrogen concentration in the water system.

This phenomenon is utilized as a method of reducing nitrogen concentration during water treatment, but shows low treatment efficiency in an oxygen-free tank due to a low denitrification rate.

For this, it is the organic carbon concentration in the reaction tank that is considered in general sewage treatment plants.

In the aerobic tank 40, ammonia is oxidized by activated sludge to exist as nitrate nitrogen, which is internally circulated and applied to the denitrification process.At this time, organic substances are decomposed by aerobic microorganisms, and after nitrification is completed, the liquid phase is separated into total carbon. As measured by analysis, 6-10mg-C/L is measured. These trace substances do not affect biological denitrification because they cannot be utilized by microorganisms even when activated sludge is operated under oxygen-free conditions.

For example, in the linear denitrification process, the influent water is directly injected into the denitrification tank, and organic substances in the influent are used as electron donors.

In this way, biological denitrification is completed if there are sufficient organic substances in the influent, but the denitrification tank is operated with a low organic carbon concentration due to the low organic substance content characteristic of domestic sewage. Therefore, an external carbon source is added to increase the carbon concentration inside the denitrification tank, thereby inducing biological denitrification.

On the other hand, it is possible to control biological denitrification by inputting an external carbon source, but if an appropriate amount of input is not set when applied to a real-scale site, the cost of inputting an external carbon source is high, leading to an increase in operating costs, resulting in very weak process economics. Will cause.

In order to operate a stable biological sewage treatment process, it is necessary to design the operating conditions of each process based on the nitrogen concentration.

For example, the nitrogen concentration in the influent is ammonia in the main form, and the nitrogen concentration in the denitrification tank is in the form of nitrate nitrogen introduced into the internal circulation from the aerobic tank and ammonia contained in the influent water.

On the other hand, in the aerobic tank 40, ammonia, which is not treated in the denitrification tank, is present as the main nitrogen concentration. The nitrogen concentration in the treated water discharged in the sewage treatment process is detected in the form of nitrate nitrogen in which ammonia is nitrated in an aerobic tank.

In order to discharge the nitrogen concentration below the standard value, the concentration should be measured when ammonia contained in the domestic sewage flowing from the flow storage tank 20 to the denitrification tank 30 is mixed with the sewage circulated in the aerobic tank 40.

As described above, the mixed sewage contains ammonia and nitrate nitrogen, and the reference nitrogen for process operation in the sewage becomes ammonia.

In addition, the aeration tank 40 may also be provided with a stirring device 42, an NH ₄ concentration detector 44, and an internal circulation path 46.

Specifically, nitrate nitrogen is discharged as nitrogen gas through a biological denitrification process, thereby reducing the nitrogen concentration in the water system. Ammonia decreases in the aerobic tank, but is converted to the form of nitrate nitrogen, so the concentration of nitrogen in the sewage does not change.

In other words, in the case of biological denitrification, it is possible to reduce the nitrogen concentration in the sewage, but in order to reduce the nitrogen concentration in the effluent in the process where the aerobic tank and the denitrification tank are intersected, it is very important to set the ammonia concentration input to the aerobic tank below the standard.

As mentioned above, it is desirable to control the initial ammonia concentration in the denitrification tank to a concentration in the range of 15-20 mg-N/L in the operation of the treatment process for nitrogen reduction in a biological sewage treatment plant.

According to this embodiment, in order to set the ammonia in the denitrification tank below the standard, the flow rate flowing from the flow storage tank 20 to the denitrification tank is set to "1Q". At this time, the factor that determines the flow rate is based on the nitrogen concentration of sewage completely mixed in the flow storage tank 20, and ammonia introduced into the denitrification tank through a ratio mixed with the flow rate circulated through the internal circulation pump in the aerobic tank 40. The concentration must be maintained within a certain range.

Next, the nitrate nitrogen concentration in the denitrification tank 30 is detected by the nitrate nitrogen concentration detection unit 34.

In this step, nitrate nitrogen is mainly detected in the supernatant, and nitrate nitrogen in a sewage treatment plant where biological denitrification and nitrification are properly operated is similar to or slightly higher than the nitrogen concentration in the input water.

As a result of the determination in the above step, when nitrate nitrogen is detected in the reference concentration range (15 mg-N/L or less), the sewage treatment process is performed.

In the case where the nitrate nitrogen is higher than the reference concentration range in the above step, the nitrate nitrogen concentration is controlled to be below the reference concentration through the internal circulation path 36 from the rear end of the denitrification tank to the front end.

Here, in the case of nitrate nitrogen, the input amount of the thermal hydrolysis solution for biological denitrification is calculated.

According to the present embodiment, when the flow rate flowing from the flow storage tank 20 to the denitrification tank 30 is set to "1Q" and the flow rate circulated in the aerobic tank 40 is input to "3Q", the denitrification tank 30 It satisfies the standard (15 mg-N/L) of nitrate nitrogen. Based on the concentration of nitrate nitrogen, it is preferable to add a thermal hydrolysis solution of about 2.5% of the flow rate.

In the above-described process, the hydraulic residence time inside the denitrification tank 30 is about 4 hours, and sheared at the rear end of the denitrification tank until the concentration of nitrate nitrogen in the effluent of the denitrification tank falls within the range of 0-1 mg-N/L. Internal circulation can be repeated.

The denitration tank 30 may be operated by adopting a sewage treatment method based on activated sludge and a method applying activated sludge method.

The flow rate flowing into the aerobic tank 40 is based on the sewage discharged from the denitrification tank 30, and the concentration of ammonia is similar to or slightly higher than the ammonia concentration introduced into the denitrification tank 30. The reason is that microorganisms are decomposed as well as biological denitrification in the absence of oxygen. That is, as the microorganisms are decomposed, organic substances and ammonia are produced, and the ammonia increases the initially introduced ammonia concentration.

According to this embodiment, the flow rate in the effluent water of the denitrification tank 30 input to the aerobic tank 40 is "4Q". In particular, the hydraulic residence time inside the aerobic tank 40 is about 2 hours, and the internal circulation from the rear end of the aerobic tank to the front end is repeated until the ammonia concentration in the effluent of the aerobic tank 40 reaches 0-1 mg-N/L. I can.

Sewage water flowing from the aerobic tank 40 to the sedimentation tank 50 is discharged after being settled for an appropriate time.

The sludge concentrated in the lower part of the settling tank 50 is introduced into the thermohydrolysis reactor 60.

According to the present embodiment, the concentrated biological sludge introduced into the thermohydrolysis reactor 60 was introduced at a concentration of about 3%, and the reaction condition in the thermohydrolysis reactor was set to 200°C and the reaction time was set to 2 hours. desirable.

FIG. 2 shows the nitrogen component, dissolved organic, and inorganic carbon concentrations in the effluent discharged when an external carbon source is not input in a sewage treatment apparatus having a linear denitrification structure as a result of the Example.

As described above, the dissolved organic carbon concentration in the effluent discharged is about 8 mg-C/L. Such carbon is not biologically available and does not affect biological denitrification even if it is circulated to the denitrification tank.

In addition, in the case of nitrate nitrogen, there is an increasing result, which is a result that denitrification is not performed because sufficient organic carbon does not exist in the denitrification tank 30.

FIG. 3 is a result of operating the treated water discharged when the thermally hydrolyzed biological sludge is added to the denitrification tank based on the influent input amount (1Q). As the sewage treatment system is stabilized, it can be seen that the concentration of nitrogen discharged is stably maintained at about 15 mg-N/L.

4 is a schematic configuration diagram of a single-phase batch reactor in addition to the reactor in which biological denitrification and nitrification are separated.

The single-phase batch bioreactor includes denitrification, nitrification, precipitation, and discharge.

Since denitrification and nitrification are performed in a single reaction tank, each step of the process described in FIG. 1 can be performed by adjusting the reaction time according to conditions.

Like the two-stage reactor, sewage and thermal hydrolysis liquid are introduced. When denitrification is complete, air is supplied to induce nitrification and treatment.

5 is a change in concentration with time when the sludge thermally hydrolyzed as a result of the Example is added in a batch reactor according to the inflow flow rate. Carbon degradable by microorganisms is consumed within the first hour, and substances that are relatively difficult to decompose decrease as oxygen-free and aerobic conditions progress.

As denitrification proceeds, nitrate nitrogen decreases to around 1 mg-N/L, and as nitrification proceeds, ammonia is oxidized to nitrate nitrogen, showing a concentration of 20 mg-N/L or less.

As described above, the method of reducing sewage sludge and operating a sewage treatment plant using its by-products according to the present invention is to increase biological denitrification efficiency in a sewage treatment plant through thermal solubilization for biological sludge generated in conventional biological sewage and wastewater treatment facilities. It is used as a carbon source for The solubilization rate and solid-liquid separation can be optimized by setting the thermohydrolysis reaction condition to 200°C and the reaction time to 2 hours.

The sewage treatment method of the present invention using this configuration will be described with reference to the drawings.

First, the sludge reduction and the sewage treatment method using the by-products of the present invention include a biological sewage treatment method between a flow storage tank and a denitrification tank, a biological sewage treatment method between a flow storage tank and an aerobic tank, and a biological sewage treatment method between the sedimentation tank and the denitrification tank. It goes on.

6 is a flow chart for explaining the biological sewage treatment method between the flow storage tank and the denitrification tank according to an embodiment of the present invention, as shown, the biological sewage treatment method between the flow storage tank and the denitrification tank of the present invention, first, the sewage pipe The step of introducing the sewage that has passed through the screen 10 from the flow storage tank 20 (S110), the step of detecting the carbon source concentration and the nitrogen concentration of the influent water in the flow storage tank 20 (S120), the detected nitrogen concentration Calculating the flow rate to be introduced into the denitrification tank 30 based on (S130) and introducing the flow rate calculated in the denitrification tank 30 (S140), by activated sludge in the aerobic tank 40 Ammonia is oxidized to exist as nitrate nitrogen, and the effluent water including sludge from the aerobic tank 40 flows into the sedimentation tank 50 and discharges the sewage after the step 150 of performing the denitrification process by internal circulation. Step 160 is included.

7 is a flow chart for explaining the biological sewage treatment method between the flow storage tank and the aerobic tank according to an embodiment of the present invention, as shown, the biological sewage treatment method between the flow storage tank and the aerobic tank is sewage in the flow storage tank 20 At the bottom of the aerobic tank 40, the sludge containing nitrate nitrogen is mixed and introduced into the denitrification tank 30. First, the nitrogen concentration detected in the flow storage tank 20 is transferred to the sludge through the return line of the aerobic tank 40. Mixing and diluting (S151), if the nitrogen concentration of the mixed denitrification tank 30 influent is higher than the reference concentration, increasing the internal circulation amount of the aerobic tank to adjust the nitrogen concentration of the mixed influent to the reference concentration (S152), and If the nitrogen concentration detected in the mixed inflow water after S152 does not exist within the reference concentration range, a step (S153) of determining to repeat step S142 is performed.

In addition, the step of introducing the thermal hydrolysis liquid introduced into the denitrification tank 30 in step S150 based on 2 -2.5% of the flow rate (1Q) input from the flow storage tank 20 to the denitrification tank 30 (S154) Wow, when the concentration of nitrate nitrogen (NO3) and nitrite nitrogen (NO2) in the effluent of the denitrification tank is not maintained below 0.5, internal circulation in the denitrification tank (S155), below the reference concentration (0.5 mg-N) /L or less) when nitrate nitrogen and nitrite nitrogen are lowered (S156), including a step of stopping the internal circulation (S157).

8 is a flow chart for explaining the biological sewage treatment method between the lower part of the sedimentation tank and the denitrification tank according to an embodiment of the present invention, as shown, the step of transferring from the lower part of the settling tank 50 to the thermohydrolysis reactor 60 (S161) and, passing through a heat exchanger while transferring biological sludge from the bottom of the sedimentation tank 50 (S162), performing thermal hydrolysis of the heated sludge in a thermohydrolysis reactor under certain conditions (S163), thermal heating It consists of a step of lowering the temperature of the sludge hydrolyzed in the lower part of the decomposition reactor 60 through a two-stage heat exchanger (S164), and a step (S165) of introducing the reduced temperature of the thermal hydrolysis liquid to the denitrification tank 30 (S165).

And the step of introducing sewage into the batch bioreactor (S171), and the step of controlling the operating conditions by adjusting the input sewage to a reference concentration (15-20 mg-N/L) in the reaction tank based on the ammonia concentration (S172) and , Step of performing biological denitrification through stirring in the bioreactor (S173), when the concentration of nitrate nitrogen (NO3) and nitrite nitrogen (NO2) in the bioreactor is kept below 1, air is removed using a lower air-gasifier. Supplying (S174), when the ammonia concentration in the reaction tank is maintained below 0.5 mg-N/L, stopping stirring and air supply (S175), the flow rate (1Q) introduced after a settling time of 30 minutes or more in the reaction tank Sewage treatment is biologically treated, including the step of discharging (S176).

In addition, the step of calculating a thermal hydrolysis liquid of 2 to 2.5% based on the flow rate (1Q) of the input sewage (S181), and the step of concentrating the sludge discharged from the batch reactor and transferring it to the thermohydrolysis reactor 60 ( S182), the step of controlling the temperature of the hydrolyzed sludge (S183), the step of transferring the reduced temperature of the thermohydrolyzed sludge to the denitrification tank 30 (S184), the step of adjusting the input amount to 2 ~ 2.5% ( S185) may be included.

In the above, the present invention has been described in detail with respect to the described embodiments, but it is obvious to those skilled in the art that various modifications and modifications are possible within the scope of the technical idea of the present invention, and it is natural that such modifications and modifications belong to the appended claims.

10: screen 20: flow storage tank
22: carbon source concentration meter 24: nitrogen concentration meter
30: denitrification tank 32: stirring device
34: nitrate nitrogen concentration meter 36: internal circulation path
40: aerobic tank 42: NH4 concentration meter
44: stirring device 46: internal circulation path
50: settling tank 52: first heat exchanger
60: thermal hydrolysis reactor 62: second heat exchanger

Claims (9)

Sewage treatment method using a sewage treatment system using sludge reduction and its by-products,
(a) the first step in which sewage that has passed through the screen from the sewage pipe flows into the flow storage tank;
(b) a second step of detecting the carbon source concentration and nitrogen concentration of the influent water in the flow storage tank;
(c) a third step of calculating the inflow flow rate of the influent water based on the nitrogen concentration;
(d) a fourth step of introducing the calculated inflow flow rate into the denitrification tank;
(e) performing a denitrification process; And
(f) discharge step;
Including,
Step (d)
The flow storage tank further comprises the step of mixing the sludge containing nitrate nitrogen at the bottom of the sewage and the aerobic tank and introducing it into the denitrification tank,
Diluting the nitrogen concentration detected in the flow storage tank with the aerobic tank sludge, and if the nitrogen concentration of the mixed denitrification tank influent is higher than the reference concentration, increasing the amount of circulation inside the aerobic tank to adjust the nitrogen concentration of the mixed inflow water to the reference concentration. Step, and if the nitrogen concentration detected in the mixed inflow water after the step of increasing the circulation amount is not within the reference concentration range, determining to repeat the step of increasing the circulation amount,
Step (f) is
Step 1 of transferring sewage from the bottom of the sedimentation tank to the thermohydrolysis reactor;
A second step of heating the biological sludge through the first heat exchanger while transferring the biological sludge from the lower part of the sedimentation tank to the thermohydrolysis reactor;
A third step of performing thermal hydrolysis of the heated sludge under constant conditions in a thermal hydrolysis reactor;
4 step of lowering the temperature of the sludge hydrolyzed in the lower part of the reactor through a second heat exchanger; And
5 step of injecting a certain amount of the thermal hydrolysis liquid whose temperature is lowered into the denitrification tank;
A method for reducing sludge and using the by-products to further include, wherein the flow rate input from the second heat exchanger to the denitrification tank is 2 to 2.5% of the flow rate input from the flow storage tank to the denitrification tank.
delete delete delete delete delete The method of claim 1,
A thermal hydrolysis reactor operated under conditions of operation conditions of 200° C. and operation time of 2 hours;
Sludge reduction and sewage treatment method using the by-products including a.
delete The method of claim 1,
The sludge reduction and the sewage treatment system using the by-products
A screen to remove solid substances mixed in sewage generated in daily life;
A flow storage tank for storing mixed inflow water passing through the screen;
A denitrification tank for receiving mixed inflow water from the flow storage tank and performing biological denitrification;
An aerobic tank for nitrifying ammonia in the effluent water after the denitrification tank;
A return line for returning the sludge containing nitrate nitrogen generated at the bottom of the aerobic tank to the denitrification tank;
A settling tank for concentrating biological sludge by receiving the effluent water discharged from the aerobic tank; And
A thermohydrolysis reactor that receives and decomposes the biological sludge collected in the settling tank;
Sludge reduction and sewage treatment method using the by-products including a.

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