Stepwise preparation method for aerobic granular sludge and water treatment method using same

Abstract

The present invention relates to a stepwise preparation method for aerobic granular sludge and a water treatment method using same, and more specifically to the preparation of aerobic granular sludge which is stable even in an environment with high concentrations of organic matter and ammonia by, while treating water in a reactor filled with activated sludge on an operating cycle including an influent step, an aeration step, a settling step, an effluent step, and an idle step at specific COD and NH4 +-N concentrations, increasing the COD and NH4 +-N concentrations stepwise with the C / N ratio maintained at 2, increasing the aeration step time, and decreasing the settling step time. The aerobic granular sludge prepared by the preparation method according to the present invention can stably remove contaminants even in an environment with a high concentration thereof, and is thus expected to increase water treatment efficiency when provided as seed sludge to a sewage treatment plant.

Description

Stepwise aerobic granular sludge production method and water treatment method using the same

[0001] The present invention relates to a stepwise aerobic granular sludge production method and a water treatment method using the same.

[0002] The present invention relates to the results of the “2024 Industry-Academic Joint Technology Development - Research on Design and Design Elements of Advanced Wastewater Treatment Process Using Bio-Biofilms” (Research Period: May 1, 2024 – December 31, 2024), as part of the research service (Phase 3 Industry-Academic Cooperation Leading University Development Project (LINC 3.0)) (Project No.: 202401220001) of Korea National University of Transportation (Research Management Agency).

[0003] Due to rapid industrialization and urbanization, water pollution is emerging as a serious social issue worldwide. In particular, ecosystem destruction and threats to human health are becoming increasingly severe, leading to a trend of gradually tightening effluent quality standards. To address these problems and create a sustainable aquatic environment, the development of efficient and economical wastewater treatment technologies is urgently required.

[0004] Conventional biological wastewater treatment methods, such as Biological Nutrient Reactors (BNR) and A2O, have disadvantages including the generation of massive amounts of waste sludge, increased chemical usage, and the need for large sites and various mechanical devices. Consequently, granule-based wastewater treatment technologies utilizing biofilm formation have recently been gaining attention, and in particular, Aerobic Granular Sludge (AGS) is being evaluated as a next-generation wastewater treatment technology based on its advantages, such as high microbial concentration and excellent settling properties.

[0005] Aerobic Granular Sludge (AGS) is a technology that improves upon the existing activated sludge process by utilizing the characteristic of microorganisms aggregated in granular form to settle by gravity. One of the features of AGS is its layered structure, which is divided into an outer aerobic layer, an intermediate anoxic layer, and an inner anaerobic layer. This enables not only the removal of organic matter but also the simultaneous removal of nitrogen (N) and phosphorus (P). AGS is primarily operated in continuous batch reactors (SBRs) and offers very high space efficiency as it can sequentially perform five stages—influent, reaction, sedimentation, discharge, and rest—within a single reactor.

[0006] The necessity of introducing AGS can be explained by the following reasons. First, it enables the treatment of high-concentration wastewater. AGS can effectively treat wastewater containing high concentrations of organic matter and nitrogen, and exhibits faster sedimentation rates compared to conventional activated sludge. Second, it allows for the reduction of equipment and operating costs. AGS eliminates the need for separate sedimentation tanks and reduces operating costs by omitting the sludge recirculation process. Third, it improves treatment efficiency. AGS can maximize reaction efficiency by increasing microbial concentration through granulation and maintaining a high concentration of microorganisms within the reaction tank. These characteristics serve as an alternative to solve the problems of bulking and foaming associated with the existing activated sludge process.

[0007] Although AGS technology has established itself as an innovative approach to improving existing activated sludge processes, some drawbacks remain. Key issues include difficulties in initial granulation, the risk of granule breakage, and sensitivity to operating conditions. Microorganisms require a certain amount of time to granulate during the initial process, and granule formation may not proceed smoothly depending on the type of microorganism and operating conditions. Furthermore, the structure of the granules can easily break due to external shocks (such as overload or low pH), and granule breakage leads to a sharp decline in treatment efficiency. In practice, wastewater treatment plants sometimes utilize externally formed granules in their processes, which can result in the need for additional plant expansion and associated costs. Due to these issues, there is a growing need for improved technologies to ensure the stable operation and enhance the operational efficiency of AGS technology.

[0008] The objective of the present invention is to perform wastewater treatment according to the operating conditions (1) to (3) below in an operating cycle including an inflow process, an aeration process, a sedimentation process, an outflow process, and a resting process within a reaction tank filled with activated sludge;

[0009] A step of monitoring aerobic granular sludge in the above reaction tank; and

[0010] The present invention provides a water treatment method using a reaction tank containing aerobic granular sludge, comprising the step of changing the operating cycle or the operating conditions of (1) to (3) below according to the above monitored value:

[0011] (1) COD concentration of 10 to 500 mg / L;

[0012] (2) NH4 + The concentration of -N is 5 to 250 mg / L; and

[0013] (3) C / N mass ratio is 1 to 5.

[0014] Another objective of the present invention is to provide aerobic granular sludge produced by the above-described method for producing aerobic granular sludge.

[0015] Another objective of the present invention is to perform wastewater treatment according to the operating conditions (1) to (3) below in an operating cycle including an inflow process, an aeration process, a sedimentation process, an outflow process, and a resting process within a reaction tank filled with activated sludge;

[0016] A step of monitoring aerobic granular sludge in the above reaction tank; and

[0017] The present invention provides a water treatment method using a reaction tank containing aerobic granular sludge, comprising the step of changing one or more of the operating cycle or operating conditions (1) to (3) below according to the above monitored value:

[0018] (1) COD concentration of 10 to 500 mg / L;

[0019] (2) NH4 + The concentration of -N is 5 to 250 mg / L; and

[0020] (3) The C / N (Carbon / Nitrogen) mass ratio is 1 to 5.

[0021] The term “activated sludge” as used in the present invention refers to a mass of biological material containing microorganisms to decompose organic matter and other pollutants in sewage or wastewater. Activated sludge is a key element of a biological treatment process in which microorganisms decompose organic matter.

[0022] As used in this invention, the term “reactor” refers to a water treatment device that performs microbial, chemical, or physical treatment processes to remove or transform pollutants within sewage or wastewater. Reactors are generally used for the chemical and biological treatment of pollutants and serve as core devices in various processes.

[0023] The term “influent” as used in this invention refers to raw water or wastewater entering a sewage treatment system. The influent serves as the starting point of the sewage treatment process, and the subsequent treatment process is determined based on the concentration and characteristics of the pollutants.

[0024] As used in this invention, "aeration" refers to a process of supplying oxygen by blowing air to remove organic matter and nitrogen compounds in sewage or wastewater through the aerobic decomposition of microorganisms. The aeration process plays an important role in decomposing pollutants by promoting the metabolic activity of microorganisms.

[0025] The term “settlement” as used in this invention refers to a process of settling solids and microbial clumps (sludge) in sewage or wastewater to the bottom by gravity. The sedimentation process is critically used to remove solids and discharge clean water.

[0026] The term “effluent” as used in this invention refers to the discharge of water purified through a sewage treatment process. Effluent is the final product of the treatment process; it must meet legal standards and is generally discharged into rivers or the sea.

[0027] As used in this invention, "Idle" refers to a stopped state during the sewage treatment process in which no activities such as water inflow, outflow, or aeration occur for a specific period of time. This stage is used to maintain the stability of the treatment system or to make changes to the process.

[0028] As used in this invention, the term “wastewater” refers to water discharged through domestic, industrial, or commercial activities, and signifies water containing pollutants. Sewage refers to domestic sewage, and wastewater refers to water discharged from industrial processes; both are treated as the primary targets of treatment processes.

[0029] The term “aerobic granular sludge (AGS)” used in the present invention refers to biologically activated sludge in which microorganisms are aggregated into porous particle forms.

[0030] The term “COD (chemical oxygen demand)” as used in this invention refers to the amount of oxygen consumed when organic pollutants in sewage or wastewater are oxidized. COD is a key indicator for evaluating the degree of water pollution and is used to determine the treatment efficiency of sewage and wastewater.

[0031] The term “C / N (Carbon / Nitrogen) ratio” as used in this invention refers to the ratio of carbon (C) to nitrogen (N) content in sewage or wastewater. The C / N ratio acts as an important factor in the growth and metabolism of microorganisms and is utilized as a key indicator for optimizing sewage treatment processes and determining nitrogen removal efficiency.

[0032] The term “AOB (ammonia-oxidizing bacteria) microorganisms” used in this invention refers to ammonia (NH3) converted into nitrite (NO2 - It refers to microorganisms that play a role in oxidizing ). AOB plays an important role in the nitrogen removal process and contributes to increasing the nitrogen removal efficiency of sewage treatment systems.

[0033] The term “NOB (nitrite-oxidizing bacteria) microorganisms” used in this invention refers to nitrite (NO2 - ) nitrate (NO3 - It refers to microorganisms that oxidize into ).

[0034]

[0035] The present invention will be described in more detail below.

[0036] One aspect of the present invention comprises the step of performing wastewater treatment according to the operating conditions (1) to (3) below in an operating cycle including an inflow process, an aeration process, a sedimentation process, an outflow process and a resting process in a reaction tank filled with activated sludge;

[0037] A step of monitoring the activated sludge in the above reaction tank; and

[0038] A method for producing aerobic granular sludge comprising the step of changing one or more of the operating cycle or operating conditions (1) to (3) below according to the value monitored above:

[0039] (1) COD concentration of 10 to 500 mg / L;

[0040] (2) NH4 + The concentration of -N is 5 to 250 mg / L; and

[0041] (3) The C / N (Carbon / Nitrogen) mass ratio is 1 to 5.

[0042] The above monitoring covers the activated sludge's sewage adaptation ability, growth rate, sedimentation performance, organic matter removal efficiency, TN removal efficiency, COD removal rate (%), and NH4 + - It may involve verifying the N removal rate (%) or the nitrite accumulation rate (NAP), but is not limited thereto. The above monitoring measurements serve as a criterion for determining whether to change the operating cycle or operating conditions. The above monitoring may be performed 1 to 10 times per day, once every 2, 3, 4, 5, 7, 10, 15, or 30 days, but is not limited thereto, and may be changed by a person skilled in the art as necessary. The above monitoring may be performed continuously without any limit on the number of times.

[0043] According to one embodiment of the present invention, the monitoring is the NH4 of the activated sludge. + - It may be checking the removal rate (%) of -N. NH4 of activated sludge+ Checking the -N removal rate (%) is one of the indicators to verify whether the microbial community stabilizes and pollutant removal efficiency is maintained in a high-concentration pollutant environment. Activated sludge with high NH4 + If the -N removal rate (%) is maintained, it is determined to be sufficiently stable, and the operating cycle or operating conditions may be changed. More specifically, the above change in the operating cycle or operating conditions is the above-mentioned monitored NH4 + - It may be performed when the -N removal rate (%) is 30% or more and 100% or less, 50% or more and 100% or less, 60% or more and 100% or less, 70% or more and 100% or less, 80% or more and 100% or less, 90% or more and 100% or less, 50% or more and 90% or less, 70% or more and 90% or less, 80% or more and 90% or less, 50% or more and 80% or less, or 70% or more and 80% or less, but is not limited thereto. Preferably, the above-mentioned change in the operating cycle or operating conditions is performed when the monitored NH4 + - It may be performed when the removal rate (%) is 70% or more and 100% or less.

[0044] The above change in operating conditions may be a change in the operating conditions of (1) and (2), but is not limited thereto. Specifically, the change in the operating condition of (1) may be to increase the concentration of COD more than before. The change in the operating condition of (2) may be to increase the concentration of NH4+-N more than before. The change in operating conditions may be to maintain the operating condition of (3). Such changes allow for the stable maintenance of the granules of aerobic granular sludge, which can be easily destroyed in high concentrations of pollutants, while maintaining the COD and nitrogen removal efficiency.

[0045] The range of increase in the concentration of the above COD is 50 to 1000 mg / L, 50 to 800 mg / L, 50 to 700 mg / L, 50 to 500 mg / L, 50 to 400 mg / L, 50 to 300 mg / L, 50 to 200 mg / L, 100 to 1000 mg / L, 100 to 800 mg / L, 100 to 700 mg / L, 100 to 500 mg / L, 100 to 400 mg / L, 100 to 300 mg / L, 100 to 200 mg / L, 150 to 1000 mg / L, 150 to 800 mg / L, 150 to 700 mg / L, 150 to 500 mg / L, 150 to It may be 400 mg / L, 150 to 300 mg / L, 150 to 200 mg / L, 200 to 1000 mg / L, 200 to 800 mg / L, 200 to 700 mg / L, 200 to 500 mg / L, 200 to 400 mg / L, or 200 to 300 mg / L, but is not limited thereto. Preferably, the range of increase in the concentration of the COD may be 200 to 400 mg / L.

[0046] The above NH4 +The range of increase in the concentration of -N is 30 to 1000 mg / L, 30 to 800 mg / L, 30 to 700 mg / L, 30 to 500 mg / L, 30 to 400 mg / L, 30 to 300 mg / L, 30 to 200 mg / L, 50 to 1000 mg / L, 50 to 800 mg / L, 50 to 700 mg / L, 50 to 500 mg / L, 50 to 400 mg / L, 50 to 300 mg / L, 50 to 200 mg / L, 100 to 1000 mg / L, 100 to 800 mg / L, 100 to 700 mg / L, 100 to 500 mg / L, 100 to 400 mg / L, It may be 100 to 300 mg / L, 100 to 200 mg / L, 150 to 1000 mg / L, 150 to 800 mg / L, 150 to 700 mg / L, 150 to 500 mg / L, 150 to 400 mg / L, 150 to 300 mg / L, or 150 to 200 mg / L, but is not limited thereto. Preferably, the above NH4 + The range of increase in the concentration of -N may be 100 to 200 mg / L.

[0047] The above change in the operating cycle may involve changing the time required for at least one of the inflow process, aeration process, sedimentation process, outflow process, and resting process, but is not limited thereto.

[0048] The above change in the operating cycle may increase the aeration process time compared to before. The range of time increase for the above aeration process is 0.5 to 50 minutes, 0.5 to 30 minutes, 0.5 to 20 minutes, 0.5 to 10 minutes, 0.5 to 8 minutes, 0.5 to 6 minutes, 0.5 to 5 minutes, 0.5 to 4 minutes, 0.5 to 3 minutes, 0.5 to 2 minutes, 1 to 50 minutes, 1 to 30 minutes, 1 to 20 minutes, 1 to 10 minutes, 1 to 8 minutes, 1 to 6 minutes, 1 to 5 minutes, 1 to 4 minutes, 1 to 3 minutes, 1 to 2 minutes, 1.5 to 50 minutes, 1.5 to 30 minutes, 1.5 to 20 minutes, 1.5 to 10 minutes, 1.5 to 8 minutes, 1.5 to 6 minutes, 1.5 to 5 minutes. The duration may be 1.5 to 4 minutes, 1.5 to 3 minutes, 1.5 to 2 minutes, 2 to 50 minutes, 2 to 30 minutes, 2 to 20 minutes, 2 to 10 minutes, 2 to 8 minutes, 2 to 6 minutes, 2 to 5 minutes, 2 to 4 minutes, or 2 to 3 minutes, but is not limited thereto. Preferably, the duration of the aeration process may be 2 to 3 minutes.

[0049] The above change in the operating cycle may reduce the time of the sedimentation process compared to before. The time reduction range of the above sedimentation process is 0.5 to 50 minutes, 0.5 to 30 minutes, 0.5 to 20 minutes, 0.5 to 10 minutes, 0.5 to 8 minutes, 0.5 to 6 minutes, 0.5 to 5 minutes, 0.5 to 4 minutes, 0.5 to 3 minutes, 0.5 to 2 minutes, 1 to 50 minutes, 1 to 30 minutes, 1 to 20 minutes, 1 to 10 minutes, 1 to 8 minutes, 1 to 6 minutes, 1 to 5 minutes, 1 to 4 minutes, 1 to 3 minutes, 1 to 2 minutes, 1.5 to 50 minutes, 1.5 to 30 minutes, 1.5 to 20 minutes, 1.5 to 10 minutes, 1.5 to 8 minutes, 1.5 to 6 minutes, 1.5 to 5 minutes, The time may be 1.5 to 4 minutes, 1.5 to 3 minutes, or 1.5 to 2 minutes, but is not limited thereto. Preferably, the time reduction range of the sedimentation process may be 1.5 to 3 minutes. As the time required for the sedimentation process is shortened, NOB microorganisms are inhibited, and the stability of the aerobic granular sludge may increase.

[0050] The above inflow process may be carried out for 1 to 20 minutes, but is not limited thereto. Preferably, the above inflow process may be carried out for 2 minutes.

[0051] The above aeration process may be carried out for 100 to 300 minutes, but is not limited thereto. Preferably, the above aeration process may be carried out for 150 to 170 minutes.

[0052] The above sedimentation process may be carried out for 1 to 30 minutes, but is not limited thereto.

[0053] The above-mentioned discharge process may take place for 1 to 30 minutes, but is not limited thereto. Preferably, the above-mentioned discharge process may take place for 5 minutes.

[0054] The above resting process may be performed for 1 to 30 minutes, but is not limited thereto. Preferably, the above resting process may be performed for 8 minutes.

[0055] The above operating cycle may be 2 to 4 hours in total, but is not limited thereto. Preferably, the above operating cycle may be 3 hours in total. Accordingly, the increase in the aeration process time and the decrease in the sedimentation process time may be the same, and the total operating cycle time is maintained the same.

[0056] The concentration of the above COD is 10 to 3000 mg / L, 10 to 1000 mg / L, 10 to 800 mg / L, 10 to 500 mg / L, 10 to 400 mg / L, 10 to 300 mg / L, 10 to 200 mg / L, 10 to 100 mg / L, 10 to 50 mg / L, 50 to 1000 mg / L, 50 to 800 mg / L, 50 to 600 mg / L, 50 to 500 mg / L, 50 to 400 mg / L, 50 to 300 mg / L, 50 to 200 mg / L, 50 to 100 mg / L, 50 to 50 mg / L, 100 to 1000 mg / L, 100 to 800 The concentration of COD may be mg / L, 100 to 600 mg / L, 100 to 500 mg / L, 100 to 400 mg / L, 100 to 300 mg / L, or 100 to 200 mg / L, but is not limited thereto. The concentration of COD refers to an initial concentration and may increase or decrease as the water treatment method of the present invention proceeds. Preferably, the concentration of COD may be 100 to 300 mg / L. In one embodiment of the present invention, the concentration of COD was 200 mg / L and was increased stepwise to finally reach 1000 mg / L.

[0057] The above NH4 +The concentration of -N is 10 to 3000 mg / L, 10 to 1000 mg / L, 10 to 800 mg / L, 10 to 500 mg / L, 10 to 400 mg / L, 10 to 300 mg / L, 10 to 200 mg / L, 10 to 100 mg / L, 10 to 50 mg / L, 50 to 1000 mg / L, 50 to 800 mg / L, 50 to 600 mg / L, 50 to 500 mg / L, 50 to 400 mg / L, 50 to 300 mg / L, 50 to 200 mg / L, 50 to 100 mg / L, 50 to 50 mg / L, 100 to 1000 mg / L, 100 to 800 It may be mg / L, 100 to 600 mg / L, 100 to 500 mg / L, 100 to 400 mg / L, 100 to 300 mg / L, or 100 to 200 mg / L, but is not limited thereto. The above NH4 + The concentration of -N refers to the initial concentration and may increase or decrease as the water treatment method of the present invention proceeds. Preferably, the NH4 + The concentration of -N may be 50 to 200 mg / L. In one embodiment of the present invention, the NH4 + The concentration of -N was 100 mg / L and was increased stepwise to finally 500 mg / L.

[0058] The above C / N mass ratio may be 0.1 to 10, 0.1 to 5, 0.1 to 3, 0.1 to 2, 0.5 to 10, 0.5 to 5, 0.5 to 3, 0.5 to 2, 1 to 10, 1 to 5, 1 to 3, or 1 to 2, but is not limited thereto. Preferably, the above C / N mass ratio may be 2. Maintaining a low C / N ratio inhibits the growth of NOB microorganisms, which helps stabilize the aerobic granular sludge, so that nitrogen removal becomes possible without the granules being destroyed even if they contain high concentrations of pollutants.

[0059] The above-mentioned changes in operating cycles or operating conditions may be made 1 to 10 times, 1 to 8 times, 1 to 6 times, 1 to 5 times, or 1 to 4 times within the entire water treatment process, but are not limited thereto. A person skilled in the art may adjust the number of changes in operating cycles or operating conditions as needed, depending on the microbial adaptation and growth rate of the activated sludge and the sedimentation performance. Preferably, the above-mentioned changes in operating cycles or operating conditions may be made 4 times within the entire water treatment process.

[0060] The above-mentioned changes to the operating cycle or operating conditions may be made whenever monitoring is performed, without any limit on the number of times. If monitoring is performed continuously, the above-mentioned changes to the operating cycle or operating conditions may also be made continuously.

[0061] The above-mentioned reactor may be an up-flow reactor, but is not limited thereto. An up-flow reactor is suitable for the formation of microbial communities because it maintains a uniform mixing state through gas injection, thereby increasing the efficiency of oxygen and nutrient supply.

[0062] The above reaction vessel may have a height / diameter ratio of 5 to 20, but is not limited thereto. Preferably, the above reaction vessel may have a height / diameter ratio of 10.

[0063] The above driving conditions may further include at least one of the following driving conditions (4) to (8), but are not limited thereto:

[0064] (4) pH;

[0065] (5) KH2PO4;

[0066] (6) MgSO 4· 7H2O;

[0067] (7) CaCl 2· 2H2O; and

[0068] (8) FeSO4· 7H2O.

[0069] The above pH may be 5 to 9, 6 to 8, 7 to 8, 7 to 7.8, 7 to 7.5, 7.2 to 8, 7.2 to 7.8, or 7.2 to 7.5, but is not limited thereto. Preferably, the above pH may be 7.2 to 7.5.

[0070] The above pH may be maintained using an NaOH solution.

[0071] The concentration of the above KH2PO4 may be 0.05 to 1.0 g / L, but is not limited thereto. Preferably, the concentration of the above KH2PO4 may be 0.18 g / L.

[0072] The above MgSO 4· The concentration of 7H2O may be 0.01 to 0.5 g / L, but is not limited thereto. Preferably, the MgSO 4· The concentration of 7H2O may be 0.09 g / L.

[0073] The above CaCl 2· The concentration of 2H2O may be 0.05 to 1.0 g / L, but is not limited thereto. Preferably, the CaCl 2· The concentration of 2H2O may be 0.18 g / L.

[0074] The above FeSO 4· The concentration of 7H2O may be 0.01 to 0.5 g / L, but is not limited thereto. Preferably, the FeSO 4· The concentration of 7H2O may be 0.09 g / L.

[0075]

[0076] Another aspect of the present invention is an aerobic granular sludge produced by the above manufacturing method.

[0077] The above aerobic granular sludge may be dominated by AOB microorganisms. The above AOB microorganisms may include Nitrosomonas. When AOB microorganisms are dominant in the aerobic granular sludge, granule stability may increase and nitrogen removal efficiency may increase.

[0078] The above-mentioned aerobic granular sludge may be dominated by EPS-producing microorganisms. The above-mentioned EPS-producing microorganisms may include Zoogloea. EPS (extracellular polymeric substances) plays an important role in protecting microorganisms and in intercellular interaction and adhesion, and thus plays an important role in the stability of the aerobic granular sludge.

[0079] The above aerobic granular sludge may be one in which NOB microorganisms are inhibited.

[0080]

[0081] Another aspect of the present invention is a step of performing wastewater treatment according to the operating conditions (1) to (3) below in an operating cycle including an inflow process, an aeration process, a sedimentation process, an outflow process and a resting process in a reaction tank filled with activated sludge;

[0082] A step of monitoring the activated sludge in the above reaction tank; and

[0083] A water treatment method using a reaction tank containing aerobic granular sludge, comprising the step of changing one or more of the operating cycle or operating conditions (1) to (3) below according to the above monitored value:

[0084] (1) COD concentration of 10 to 500 mg / L;

[0085] (2) NH4 + The concentration of -N is 5 to 250 mg / L; and

[0086] (3) The C / N (Carbon / Nitrogen) mass ratio is 1 to 5.

[0087] The description of the activated sludge, reactor, operating cycle, operating conditions, aerobic granular sludge, and monitoring above is the same as described above.

[0088] The present invention relates to a stepwise aerobic granular sludge production method and a water treatment method using the same. Specifically, within a reaction tank filled with activated sludge, a specific COD concentration and NH4 are treated in an operating cycle including an inflow process, an aeration process, a sedimentation process, an outflow process, and a resting process. + While proceeding with water treatment at a -N concentration, gradually increasing the COD concentration and NH4 while maintaining the C / N ratio at 2 + The goal is to produce stable aerobic granular sludge even in high-concentration organic matter and ammonia environments by increasing the concentration of N, increasing the aeration process time, and decreasing the sedimentation process time.

[0089] The aerobic granular sludge produced by the manufacturing method of the present invention is effective for granular stability and nitrogen removal by making Zoogloea, which contributes to the growth of AOB microorganisms and EPS, dominant and inhibiting NOB microorganisms. In particular, the present invention is expected to enhance water quality improvement effects and reduce process operating costs by stably removing COD, ammonia, and total nitrogen (TN) even in environments with high concentrations of pollutants.

[0090] In addition, it is expected that the installation costs of the sewage treatment plant can be reduced by decreasing the site area compared to existing methods, and maintenance costs can be reduced by decreasing the amount of excess sludge generated.

[0091] Figure 1 is a drawing of a Lap-Scale Up-flow reactor.

[0092] Figure 2 is a schematic diagram of the operation of an up-flow reactor.

[0093] Figure 3 shows the results of visual observation of the initial activated sludge and the aerobic granular sludge formed after 95 days.

[0094] Figure 4 shows the results of microscopic observation of the initial activated sludge and the aerobic granular sludge formed after 95 days.

[0095] Figure 5 shows the results of monitoring the MLSS and SVI5 measurements of the sludge for 95 days.

[0096] Figure 6 shows the results of monitoring the COD removal efficiency in the reactor for 95 days.

[0097] Figure 7 shows NH4 in the reaction vessel + This is the result of monitoring the -N removal efficiency for 95 days.

[0098] Figure 8 shows NO in the reaction vessel x This is the result of monitoring the concentration of NAP and TN removal efficiency for 95 days.

[0099] Figure 9 shows the results of comparing changes in microbial communities within aerobic granular sludge at the genus level.

[0100] One aspect of the present invention comprises the step of performing wastewater treatment according to the operating conditions (1) to (3) below in an operating cycle including an inflow process, an aeration process, a sedimentation process, an outflow process and a resting process in a reaction tank filled with activated sludge;

[0101] A step of monitoring the activated sludge in the above reaction tank; and

[0102] A method for producing aerobic granular sludge comprising the step of changing one or more of the operating cycle or operating conditions (1) to (3) below according to the value monitored above:

[0103] (1) COD concentration of 10 to 500 mg / L;

[0104] (2) NH4 + The concentration of -N is 5 to 250 mg / L; and

[0105] (3) The C / N (Carbon / Nitrogen) mass ratio is 1 to 5.

[0106] The above monitoring may be performed continuously without any limit on the number of times.

[0107] The above monitoring is the NH4 of the activated sludge + - It may be checking the removal rate (%).

[0108] The above-mentioned change in operating cycle or operating conditions is the above-mentioned monitored NH4 + - It may be performed when the removal rate (%) is 70% or more and 100% or less.

[0109] The above change in driving conditions may be a change in the driving conditions of (1) and (2).

[0110] The change in operating conditions of (1) above may increase the concentration of COD more than before.

[0111] The change in operating conditions of (2) above is NH4 + It may be increasing the concentration of -N more than before.

[0112] The range of increase in the concentration of the above COD may be 200 to 400 mg / L.

[0113] The above NH4 + The range of increase in the concentration of -N may be 100 to 200 mg / L.

[0114] The above change in the operating cycle may involve changing the time required for at least one of the inflow process, aeration process, sedimentation process, outflow process, and resting process.

[0115] The above change in the operation cycle may increase the aeration process time more than before. The increase in the aeration process time may be 2 to 3 minutes.

[0116] The above change in the operating cycle may reduce the time of the sedimentation process compared to before. The reduction in the time of the sedimentation process may be 1.5 to 3 minutes.

[0117] The above inflow process may take place for 2 minutes.

[0118] The above aeration process may be carried out for 150 to 170 minutes.

[0119] The above sedimentation process may be carried out for 1 to 30 minutes.

[0120] The above leakage process may take place for 5 minutes.

[0121] The above resting process may take place for 8 minutes.

[0122] The above operating cycle may be a total of 3 hours.

[0123] The concentration of the COD above may be 100 to 300 mg / L.

[0124] The above NH4 + The concentration of -N may be 50 to 200 mg / L.

[0125] The above C / N mass ratio may be 2.

[0126] The above reaction vessel may be an up-flow reaction vessel.

[0127] The above reaction vessel may have a height / diameter ratio of 5 to 20.

[0128] The above driving conditions may further include at least one of the following driving conditions (4) to (8):

[0129] (4) pH;

[0130] (5) KH2PO4;

[0131] (6) MgSO 4· 7H2O;

[0132] (7) CaCl 2· 2H2O; and

[0133] (8) FeSO 4· 7H2O.

[0134] The above pH may be 7.2 to 7.5.

[0135] The concentration of the above KH2PO4 may be 0.18 g / L.

[0136] The above MgSO 4· The concentration of 7H2O may be 0.09 g / L.

[0137] The above CaCl 2· The concentration of 2H2O may be 0.18 g / L.

[0138] The above FeSO 4· The concentration of 7H2O may be 0.09 g / L.

[0139] One or more specific examples are described in more detail below through embodiments. However, these embodiments are intended to illustrate one or more specific examples and the scope of the present invention is not limited to these embodiments.

[0140]

[0141] Example 1. Design of a Lab-Scale Up-flow Reactor

[0142] Example 1-1. Design

[0143] Previous studies have mainly utilized sequencing batch reactor (SBR) systems to culture aerobic granular sludge (AGS). However, this method had limitations, such as requiring a long time for granule formation and reduced efficiency when treating wastewater containing high concentrations of ammonia and organic matter.

[0144] In this invention, a single-zone reactor was designed to maximize mixing efficiency and oxygen transfer efficiency. In addition, the ratio of organic matter to ammonia was optimized to 2:1 to promote the formation of granular sludge even in a high-concentration ammonia environment.

[0145] A glass reactor was fabricated to prevent internal corrosion and ensure easy visual observation of the reaction process. The fabricated reactor was designed as an up-flow type with a capacity of 1.8 L, and a single-zone structure was adopted so that the entire volume could be utilized for the reaction without internal compartments. This was intended to maximize the mixing efficiency of the reactants and ensure reaction uniformity. The height-to-diameter ratio of the reactor was set to 10 to achieve an optimal balance between oxygen transfer efficiency and sedimentation performance (Fig. 1). In addition, a microbubble forming device was installed at the bottom of the reactor to maintain a uniform mixing state during gas injection. In this invention, experiments were conducted under a gas injection condition of 5.5 L / min (Fig. 2).

[0146]

[0147] Example 1-2. Operating Conditions

[0148] The experiment was conducted for a total of 95 days, and the operation stages of the reactor were distinguished by applying changes in concentration and sedimentation time in stages during the experiment period, and the treatment performance and reaction characteristics of microorganisms at each stage were compared and analyzed.

[0149] The experiment was conducted under summer conditions. The temperature of the up-flow reactor was maintained at the laboratory room temperature (25±2℃) and proceeded without additional temperature adjustment. The pH within the reactor was maintained in the range of 7.2 to 7.5 using a concentrated NaOH solution. Distilled water was used as the solvent for the artificial wastewater supplied to the reactor, and the composition of the artificial wastewater is summarized in Table 1 below. The artificial wastewater was prepared to achieve a C / N ratio of 2 by adjusting the concentrations of COD (Chemical Oxygen Demand) and NH4+-N. Sodium acetate and glucose were used as COD sources, and the concentrations were set in the range of 200 to 1000 mg / L. NH4 +Ammonium chloride (NH4Cl) was used for -N, and the concentration was added in the range of 100 to 500 mg / L. COD and NH4 + The inflow concentration of -N was set to gradually increase as the stage progressed from I to IV (Table 2).

[0150] The operation cycle of the reactor was divided into eight cycles based on a 24-hour period. One cycle consists of an initial inflow process of 2 minutes, an aeration process of 155 to 162 minutes, a sedimentation process of 3 to 10 minutes, an outflow process of 5 minutes, and a resting process of 8 minutes. As the stage progresses from I to IV, the aeration time is increased and the sedimentation time is decreased (Table 2).

[0151] 단계성분농도(g / L)Phase ⅠDextrose2.7Sodium Acetate trihydrate2.7Potassium phosphate, monobasic0.18Ammonium Chloride10.8Magnesium Sulfate, Heptahydrate0.09Calcium chloride dihydrate0.18Ferrous Sulfate heptahydrate0.09Phase ⅡDextrose5.4Sodium Acetate trihydrate5.4Potassium phosphate, monobasic0.18Ammonium Chloride20Magnesium Sulfate, Heptahydrate0.09Calcium chloride dihydrate0.18Ferrous Sulfate heptahydrate0.09Phase ⅢDextrose7Sodium Acetate trihydrate7Potassium phosphate, monobasic0.18Ammonium Chloride31.5Magnesium Sulfate, Heptahydrate0.09Calcium chloride dihydrate0.18Ferrous Sulfate heptahydrate0.09Phase ⅣDextrose13Sodium Acetate trihydrate15Potassium phosphate, monobasic0.18Ammonium Chloride41.5Magnesium Sulfate, Heptahydrate0.09Calcium chloride dihydrate0.18Ferrous Sulfate heptahydrate0.09

[0152]

[0153] PhaseⅠⅡⅢⅣTime (d)1~1415~6667~8384~95Influent (min / cycle)2222React (min / cycle)155158160162Settle (min / cycle)10753Effluent (min / cycle)5555Idle (min / cycle8888Influent COD (mg / L)2004006001000Influent NH4 + -N (mg / L)100200300500

[0154]

[0155] Examples 1-3. Sludge Characteristics

[0156] The activated sludge used in the experiment was from the bioreactor at the Chungju Wastewater Treatment Plant (daily treatment capacity: 75,000 m³ 3 Samples were collected from the sampling port of the reactor ( / day). The initial MLSS concentration was set to 1.78 g / L and the SVI5 (5-minute sludge volume index) to 421.3 mL / g, resulting in a degraded sedimentation performance. Through these initial conditions, the aim was to analyze the sedimentation characteristics within the reactor and evaluate the improvement effects according to operating conditions. Sludge was collected daily from the sampling port of the reactor and monitored.

[0157]

[0158] Example 2. Observation of Aerobic Granular Sludge (AGS)

[0159] The initial sludge exhibited a loose and unstable structure dominated by filamentous bacteria, but through short settling time operation, sludge with low settling ability was selectively discharged.

[0160] At the D+95 day mark, the AGS was observed to be in a dense granular form with a diameter of 0.8 to 2 mm or more (Fig. 3). This is attributed to the stepwise reduction in settling time and high-intensity aeration accelerating the granulation rate. After the formation of AGS, the sludge structure changed from a loose form to a dense granular form, which improved the settling capacity and the ability to maintain microbial concentration (Fig. 4).

[0161]

[0162] Example 3. Measurement of Sludge Volume Index (SVI)

[0163] Generally, the SVI value of activated sludge ranges from 50 ≤ SVI ≤ 150, whereas mature ASG exhibits excellent settling performance with an SVI ≤ 50. Experimental results showed an inverse relationship between MLSS and SVI5 (Fig. 5), suggesting that settling capacity increased even when the microbial concentration was maintained. Finally, MLSS was observed to be 4.17 g / L and SVI5 23 mL / g, which signifies an approximately 18-fold improvement in settling performance compared to the initial values ​​(Table 3).

[0164] DATE Reactor No. 1 (AGS) Year (2024) DATE LESS VSS VSS / TS SSS VI 5 (DAY) (g / L) (g / L) (%) (mL / g) 24.07.02 11.78 1.64 0.92 4 21.32 4.07.04 3 2.23 2.02 0.91 24 9 24.07.109 2.13 1.98 0.93 17 7 24.07.16 15 2.24 2.16 0.96 13 6 24.07.19 18 2.35 2.24 0.95 15 4 24.07.25 24 3.45 3.25 0.94 12 124.07.29 28 3.62 3.45 0. 9511024.08.01313.233.140.9710424.08.05353.463.250.9410124.08.19494.384.260.977824.08.29595.435.120.947624.09.10715.375.070.947424.09.19804.784.50.942824.09.24854.464.160.932624.10.01924.324.030.932124.10.04954.173.80.9123

[0165]

[0166] Example 4. COD Removal Efficiency

[0167] The COD concentration was gradually increased from 200 to 400 to 600 to 1000 mg / L, while the C / N ratio was maintained at 2. In the initial stages (Stages I and II, COD 200–400 mg / L), stable removal performance was observed with an average removal efficiency of 84.31±8.9% (Fig. 6). In Stage III (COD 600 mg / L), a lack of microbial adaptation was observed due to the increased concentration, and the removal efficiency temporarily decreased. In Stage IV (COD 1000 mg / L), as the microbial community adapted, the average removal efficiency recovered and stabilized at 90±1.5%.

[0168] These results suggest that microbial communities can maintain continuous and high removal efficiency even in high-concentration organic environments once they undergo an adaptation phase.

[0169]

[0170] Example 5. NH4+-N removal efficiency

[0171] NH4 + The -N concentration was gradually increased from 100 → 200 → 300 → 500 mg / L, while the C / N ratio was maintained at 2. In the initial stage (I), the average removal efficiency was 88.57±7%, showing stable efficiency (Fig. 7). In stages II and III, a lack of microbial adaptation was observed due to the increase in concentration, and the removal efficiency temporarily decreased. Stage IV (NH4 + At -N 500 mg / L), the average removal efficiency recovered to 71.23±9.3%. This confirmed that the AGS process has the ability to effectively adapt to high-concentration ammonia environments and maintain consistently high removal efficiency.

[0172]

[0173] Example 6. NOx, NAP Monitoring, and TN Removal Efficiency

[0174] NO depending on the stage-by-stage operation of the reactor x , NAP was monitored, and TN removal efficiency was measured (Fig. 8). NO2 - The concentration showed a gradual increasing trend after Step II, confirming that partial nitrification conditions (PN / D) were maintained. NO2 - With increasing concentration, the nitrite accumulation rate (NAP) increased to an average of 76.5±3.8%. NO3 - The average concentration was 22.4±4.8 mg / L, indicating that NOB (Nitrite-Oxidizing Bacteria) microorganisms were being controlled by the effluent. The TN removal efficiency averaged 38.3±10.1% after Stage III, confirming that the partial nitrification and denitrification (SND) processes operate effectively and can achieve high TN removal efficiency even in high-concentration nitrogen environments.

[0175]

[0176] Example 7. Microbial community analysis

[0177] Nitromonas, an AOB (Ammonia-Oxidizing Bacteria) microorganism, accounted for 15.52% of the granules, indicating that it is dominant as the major AOB microorganism (Fig. 9). Conversely, NOB microorganisms (Nitrospirota) were found to be inhibited within the granules. Zoogloea, which contributes to organic matter decomposition and EPS production, accounted for 23.23% of the granules, showing a significant dominance over flocs. These results demonstrate that inhibiting the growth of NOB microorganisms and promoting the dominance of AOB and EPS-producing microorganisms contributes to nitrogen removal and granule stability.

[0178]

[0179] Synthesizing the results to date, the formation of AGS was successfully achieved through a stepwise operation strategy; the AGS secured a dense structure and excellent sedimentation performance (SVI ≤ 50), and the maintenance of microbial concentration and sedimentation efficiency were significantly improved. High concentrations of COD and NH4 + Even in a -N environment, the microbial community of the AGS process adapted flexibly and effectively controlled sludge characteristics to maintain high nitrogen removal efficiency. In particular, short settling times and a low C / N ratio are considered to play a crucial role in inhibiting NOB microorganisms and stabilizing the AGS. The step-by-step design and operation strategy of the present invention demonstrated that stable process operation is possible even in environments with high concentrations of pollutants.

[0180]

[0181] The present invention has been described above with reference to its preferred embodiments. Those skilled in the art will understand that the present invention may be embodied in modified forms without departing from the essential characteristics of the invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the invention is defined by the claims, not by the foregoing description, and all variations within the scope of the claims should be interpreted as being included in the invention.

[0182] The present invention relates to a stepwise aerobic granular sludge production method and a water treatment method using the same. Specifically, within a reaction tank filled with activated sludge, a specific COD concentration and NH4 are treated in an operating cycle including an inflow process, an aeration process, a sedimentation process, an outflow process, and a resting process. + While proceeding with water treatment at a -N concentration, gradually increasing the COD concentration and NH4 while maintaining the C / N ratio at 2 + The invention produces stable aerobic granular sludge even in environments with high concentrations of organic matter and ammonia by increasing the concentration of N, increasing the aeration process time, and decreasing the sedimentation process time. The aerobic granular sludge produced by the method of the present invention can stably remove pollutants even in environments contaminated with high concentrations, and thus can improve water treatment efficiency when provided as seeding sludge to a sewage treatment plant.

Claims

1. A step of performing wastewater treatment according to the operating conditions of (1) to (3) in an operating cycle including an inflow process, an aeration process, a sedimentation process, an outflow process and a resting process in a reaction tank filled with activated sludge; A step of monitoring the activated sludge in the above reaction tank; and A method for producing aerobic granular sludge comprising the step of changing one or more of the operating cycle or operating conditions (1) to (3) below according to the value monitored above: (1) COD concentration of 10 to 500 mg / L; (2) NH4 + The concentration of -N is 5 to 250 mg / L; and (3) The C / N (Carbon / Nitrogen) mass ratio is 1 to 5.

2. A method for producing aerobic granular sludge according to claim 1, wherein the monitoring is to verify the sewage adaptation ability, growth rate, sedimentation performance, organic matter removal efficiency, or TN removal efficiency of the activated sludge.

3. In paragraph 1, the monitoring is the NH4 of the activated sludge + It is to check the -N removal rate (%), and The above-mentioned change in operating cycle or operating conditions is the above-mentioned monitored NH4 + A method for producing aerobic granular sludge, wherein the -N removal rate (%) is 70% or more and 100% or less.

4. In paragraph 1, the change in the operating conditions is to change the operating conditions of (1) and (2) while maintaining the operating conditions of (3), and The change in operating conditions of (1) above increases the concentration of COD more than before, and The change in operating conditions of (2) above is NH4 + A method for producing aerobic granular sludge, which increases the concentration of -N more than before.

5. In paragraph 4, the range of increase in the concentration of the COD is 100 to 500 mg / L, and The above NH4 + A method for producing aerobic granular sludge, wherein the range of increase in the concentration of -N is 50 to 250 mg / L.

6. A method for producing aerobic granular sludge according to claim 1, wherein the change in the operating cycle is to increase the time of the aeration process more than before and decrease the time of the sedimentation process more than before.

7. In paragraph 6, the time increase range of the aeration process is 1 to 10 minutes, and A method for producing aerobic granular sludge, wherein the time reduction range of the above sedimentation process is 1 to 10 minutes.

8. In paragraph 1, the above inflow process is carried out for 1 to 20 minutes, and The above aeration process is carried out for 100 to 200 minutes, and The above sedimentation process is carried out for 1 to 30 minutes, and The above-mentioned leakage process takes place for 1 to 30 minutes, and A method for producing aerobic granular sludge, wherein the above resting process is carried out for 1 to 30 minutes.

9. A method for producing aerobic granular sludge according to claim 1, wherein the change in the operating cycle or operating conditions is performed 1 to 10 times within the entire water treatment process.

10. A method for producing aerobic granular sludge according to claim 1, wherein the reaction tank is an up-flow reaction tank.

11. A method for producing aerobic granular sludge according to claim 1, wherein the reaction vessel has a height / diameter ratio of 5 to 20.

12. A method for producing aerobic granular sludge according to claim 1, wherein the operating conditions further include at least one of the following operating conditions (4) to (8): (4) pH is 7 to 8; (5) KH2PO4 0.05 to 1.0 g / L; (6) MgSO 4· 7H2O 0.01 to 0.5 g / L; (7) CaCl 2· 2H2O is 0.05 to 1.0 g / L; and (8) FeSO 4· 7H2O is 0.01 to 0.5 g / L.

13. Aerobic granular sludge produced by the manufacturing method of any one of paragraphs 1 to 12.

14. In paragraph 13, the aerobic granular sludge is an aerobic granular sludge in which AOB (Ammonia-Oxidizing Bacteria) microorganisms are dominant and NOB (Nitrite-Oxidizing Bacteria) microorganisms are inhibited.

15. A step of performing wastewater treatment according to the operating conditions of (1) to (3) in an operating cycle including an inflow process, an aeration process, a sedimentation process, an outflow process and a resting process in a reactor filled with activated sludge; A step of monitoring the activated sludge in the above reaction tank; and A water treatment method using a reactor containing aerobic granular sludge, comprising the step of changing the operating cycle or one or more of the operating conditions of (1) to (3) below according to the value monitored above: (1) COD concentration of 10 to 500 mg / L; (2) NH4 + The concentration of -N is 5 to 250 mg / L; and (3) The C / N (Carbon / Nitrogen) mass ratio is 1 to 5.

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