KR100823691B1 - Advanced waste-water treatment system for decreasing sludge and erasing nitrogen and phosphorus - Google Patents

Abstract

An advanced wastewater treatment method for suppressing the generation of sludge and removing nitrogen and phosphorus is provided to primarily remove solids, degrade organic matters and remove phosphorous, to simultaneously increase the nitrogen removal effect and suppress the generation of sludge consistently, and to secondly treat the organic matters and reduce sludge at the same time. An advanced wastewater treatment method comprises the steps of: carrying out a upflow filtration by a upflow filter tank(10) in which suspended solids are settled by a filtration layer, which easily releases phosphorous from a lower part thereof by anaerobic reaction, and which biodegrades organic matters and removes nitrogen in an upper part thereof; transferring a supernatant to an aerobic tank(20) and biologically treating wastewater flown into the aerobic tank using oxygen continuously supplied through an air diffuser from an air supply device; flowing wastewater that has passed through the aerobic tank into a settling tank(30), and gravitationally separating wastewater, a microorganism-containing sludge, and a supernatant from influent that has been received from the aerobic tank within the settling tank to transfer the supernatant to an anoxic tank(40), transfer the settled sludge to a sludge thickener(50) or return the settled sludge to the aerobic tank, and discharge excessive sludge to the outside; simultaneously remove nitrogen from sludge flown in and consistently suppressing the generation of sludge at the same time by the anoxic tank installed in rear of the settling tank, and discharging the supernatant or returning the supernatant to the aerobic tank in accordance with a discharge standard; and retreating thickened sludge that has been transferred to a thermophilic aerobic reactor(60) through the sludge thickener, and returning the retreated thickened sludge to the aerobic tank.

Description

Advanced waste-water treatment system for decreasing sludge and erasing nitrogen and phosphorus

1: ATAD basic process chart

2: OSA basic process diagram

3: Basic process diagram of the present application

4: Material balance map when applying the present system

5 is an exemplary view of a modified application of the basic process of the present application

6 is another illustration of the modification of the basic process of the present application

※ Explanation of code for main part of drawing

10 upflow filtration tank 20 aerobic tank

30: sedimentation tank 40: anoxic tank

50: sludge thickening tank 60: high temperature aerobic reaction tank

100: downward flow 101: upward flow

102: internal conveying line 103: excess sludge discharge line

104: sludge conveying line 105: high temperature aerobic reactor inlet line

106: high temperature aerobic reactor outlet line 107: conveying line from the concentration tank

In general, wastewater containing organic pollutants, nitrogen, and phosphorus depletes dissolved oxygen in water, destroying aquatic ecosystems, and eutrophicating water in lakes and reservoirs.

Therefore, to prevent water pollution of rivers. Pollutants and organonutrients contained in the wastewater should be removed before they enter the body of water, such as rivers.

O to remove it. As a treatment method of wastewater treatment facilities, many biological treatment methods that are excellent in economics are applied. Among the biological treatment methods, organic matters using microorganisms such as activated sludge method and advanced treatment are removed, but microorganisms grown during organic matter removal process Sludge is generated.

As a representative biological treatment method, activated sludge method grows as the microorganism ingests and decomposes organic matter in the wastewater and proceeds to nitrification as the waste water is continuously injected into the aeration tank. As a result, some of the precipitate is returned to the aeration tank in the form of activated sludge, and some excess sludge is discarded to maintain an appropriate level of microorganisms in the aeration tank to remove nitrogen, phosphorus, etc. together with organic matter decomposition in the wastewater.

This activated sludge method has long been recognized that it has an excellent effect on the treatment of organic matter in wastewater, but it is not suitable for the effective removal of organic matter and nitrogen from wastewater containing high concentrations of organic matter and nitrogen, and the amount of surplus sludge increases. I have a problem.

The portion of activated sludge precipitated in the sedimentation tank of the biological water treatment process such as activated sludge method is sent to the aeration tank for reuse and the remaining sludge except the sludge is called surplus activated sludge.

In biological treatment of wastewater or sewage, microorganisms degrade suspended or dissolved solids, some are oxidized to carbon dioxide (CO2) and water (H20), and others are converted to microbial cells through synthesis. The amount of excess sludge generated decreases as the load of biochemical oxygen demand (BOD) decreases and the branching time decreases.

The cost of treating excess sludge is about 40-60% of the total sewage treatment costs, and secondary pollution from sludge treatment is emerging as a new environmental problem. Although actively progressing, the problem of the need to perform sludge reduction and advanced treatment at the same time has not been solved.

In order to solve the sludge problem, which is a chronic problem of activated sludge method in wastewater treatment, the present study has conducted a lot of researches from the 60s and 1970s as a sludge reduction measure to reduce sludge generation and smoothly perform advanced treatment of wastewater. Introduces the advanced ATAD process to advanced treatments, installs an anoxic tank at the rear of the settling tank to combine the advantages of OSA process with excellent denitrification and organic decomposition, and develops a new process to install an upstream filter tank at the pretreatment stage. The present invention relates to a completed invention in the process of finding a way to supplement the shortcomings of the existing process, to save the cost of the field equipment, and maximize the water treatment efficiency.

The present invention primarily forms a biofilm while depositing solids by performing an inflow of an upflow filtration tank to remove nitrogen and phosphorus and to perform an advanced treatment method to reduce the amount of sludge generated, thereby forming phosphorus through a lower anaerobic reaction. In addition to promoting elution more effectively, organic matters are removed, organic matters are removed, phosphorus and nitrification reactions are carried out in an aerobic tank, and in the anoxic tank at the end of the sedimentation tank, the technical idea of reducing sludge production by stably inhibiting denitrification and microbial metabolism Have

In addition, the sludge is returned from the sedimentation tank and the excess sludge is concentrated through the concentration tank, and then the reaction is returned to the aerobic tank after the reaction in the high temperature aerobic reactor to remove the sludge and maintain a stable amount of microorganisms in the aerobic tank. The purpose of the present invention is to provide a sludge reduction effect at the same time as a result, to remove nitrogen and phosphorus and to provide an advanced treatment method for reducing the amount of sludge generated.

The present invention is to provide a high treatment technology for reducing the amount of sludge generated at the same time to remove nitrogen and phosphorus more efficiently in the treatment of high or low concentration of wastewater.

The present application inhibits sludge generation and nitrogen. As an advanced treatment technology to remove phosphorus, the upstream filtration tank is installed in the previous stage of the aerobic tank, and when the incoming sewage flows from the bottom of the upstream filtration tank by gravity, the biodegradation of organic substances and nutrients contained in the waste water is caused by contact with microorganisms. In the middle layer of the upflow filtration tank, a crushed stone filtration tank is installed, and the supernatant liquid corresponding to the inflow is transferred to the oxygen tank through the outlet of the upper layer while performing the solid removal, organic decomposition and phosphorus removal processes. To achieve.

The treated materials introduced into the oxygen tank are biologically treated using oxygen continuously supplied from the air supply unit through the diffuser,

Treated material through the aerobic tank flows into the sedimentation tank, and the sedimentation tank separates the inflow water from the aerobic tank into sediment sludge and supernatant containing the treated matter and microorganisms by gravity, and the supernatant is transferred to an anoxic tank, and the sludge sludge concentration tank is settled. Will be transferred to.

An anoxic tank is installed at the end of the settling tank to increase the nitrogen removal effect and to continuously suppress sludge generation.

Sludge precipitated in the sedimentation tank is provided to the aerobic tank or solubilized in a high temperature aerobic digestion tank to be returned to the aerobic tank to provide a waste water treatment process to reduce the sludge at the same time as the treatment of organic matter, such as nitrogen and phosphorus. It has a technical idea to start.

Therefore, the present application is nitrogen and phosphorus through the advanced treatment method provided, including upstream filtration tank (10), aerobic tank (20), sedimentation tank (30), anoxic tank (40), sludge concentration tank (50) and high temperature aerobic reaction tank (60). The present invention relates to an advanced treatment method for removing sludge and reducing the amount of sludge produced.

The upflow filtration tank 10 has a filtration layer, in which floating solids are deposited by the filtration layer, and a biofilm is formed to facilitate phosphorous elution by anaerobic reaction at the lower part and to decompose organic matter and remove nitrogen by the microorganism at the upper part. step;

The supernatant liquid corresponding to the inflow of the object to be treated into the upflow filtration tank 10 is transferred to the aerobic tank 20 through the outlet of the upper layer, and the object to be introduced into the aerobic tank is continuously supplied from the air supply apparatus through the diffuser. Providing a biological treatment using;

The treated material that passes through the aerobic tank 20 flows into the settling tank 30, and the sedimentation tank 30 separates the influent from the aerobic tank 20 into sediment sludge and supernatant containing the to-be-processed material and microorganisms by gravity. The supernatant is transferred to the anaerobic tank 40 and the settling sludge is transferred to the concentrating tank 50, cyclized to the aerobic tank 20, or the excess sludge is discharged.

The anaerobic tank 40 is installed at the rear end of the settling tank 30 to remove nitrogen from the introduced sludge and act to continuously suppress sludge generation, while the supernatant is discharged according to the discharge standard or cyclized into the aerobic tank 20. ;

The concentrated sludge transferred to the high temperature aerobic reaction tank 60 through the sludge thickening tank 50 is reprocessed and recycled to the aerobic tank 20;

Provided is an advanced treatment method provided.

Below, it looks at the background of the present invention.

As a representative process for reducing sludge generation, the ATAD (Autothermal Thermophilic Aerobic Digestion) process, which was started in Europe in the 1960s as a self-heating high temperature aerobic treatment method, was developed and has been used in various ways until now. The process is simply shown in Fig. 1 and briefly mentioned, the basic configuration of the aeration tank, the sedimentation tank and the ATAD reaction tank for solubilization requires a high concentration inflow for the high temperature aerobic reaction in the ATAD reactor for solubilization, and the overload problem of the aeration tank MLSS and It was a situation where water treatment could not be found as a process for reducing sludge only due to problems such as difficulty in controlling the conveyed amount.

Since then, a method for reducing sludge while efficiently carrying out advanced treatment has been studied. In 1992, P. Chudoba proposed an Oxa-Settling-AnOxic (Energy-Uncoupling) process. As a representative method for reducing the pressure simply shown in Figure 2 to refer briefly, it is composed of aerobic tank-sedimentation tank-anoxic tank to suppress the microbial biological metabolism of excess sludge withdrawn from the sedimentation tank to reduce the excess sludge by about 44% Has been reported.

However, the OSA process is a method to reduce sludge production by suppressing effective denitrification and biological metabolism by installing an anaerobic tank at the end of the settling tank, but requires a separate chemical input and facility for phosphorus removal and suppresses metabolism. Due to the inhibition of the activity of the aerobic microorganism due to the degradation of the efficiency of water treatment and sludge outflow had a problem that can occur.

The present application tried to experiment with the idea of the invention to obtain a sludge reduction effect by using the mixing process of the ATAD method and the OSA method with the idea of the invention to obtain a satisfactory removal effect of nitrogen and delivery. The present invention has been completed by confirming that a significant effect can be obtained.

An advanced treatment process for reducing the amount of sludge generated herein is disclosed and provided in FIG. 3, in particular, an upflow filtration tank 10 is installed in the previous stage of the aerobic tank 20, and the bottom of the upflow filtration tank is gravity-flowed. When it is introduced from, the biodegradation of organic substances and nutrients contained in the waste water starts in contact with microorganisms.The crushed stone filtration tank is installed in the middle layer of the upflow filtration tank to perform solids removal, organic matter decomposition and phosphorus removal process. The anoxic tank 40 is provided at the rear end of the settling tank 30 to enhance the nitrogen removal effect and at the same time to continuously suppress sludge generation.

In the high-treatment process of the present application, the supernatant corresponding to the inflow of the water to be processed into the upflow filtration tank 10 is transferred to the aerobic tank 20 through the outlet of the upper layer, and the processing material introduced into the aerobic tank is transferred from the air supply device. The biological treatment is performed using oxygen continuously supplied through the diffuser, and the treated material passing through the aerobic tank 20 flows into the sedimentation tank 30, and the sedimentation tank 30 receives gravity from the aerobic tank 20. By the solid-liquid separation of the sludge and supernatant containing the to-be-processed matter and microorganism by the supernatant is transferred to the anaerobic tank 40, the precipitated sludge is transferred to the high temperature aerobic reaction tank (60) through the sludge concentration tank (50) and recycled Has

 The filtration layer of the upflow filtration tank 10 may be composed of crushed stone or other filter media that are easily adhered to microorganisms. The filtration layer primarily deposits floating solids and forms a biofilm. In the anaerobic reaction, phosphorous elution is easy and the upper part is provided to decompose organic matters and remove nitrogen by microorganisms. In this process, BOD 30-40%, SS 40-50%, TN 5%, and TP 25% are removed. .

In the aerobic tank 20, denitration reaction takes place in the upflow filtration tank 10 and activated sludge that is depleted due to the denitrification reaction is returned and joined. Therefore, the intake of microorganisms facilitates the decomposition of organic substances. In addition, the sludge in the high temperature aerobic reaction tank (60) after the high temperature aerobic reaction is introduced into the aerobic tank 20 through the 106 conveying path to re-decompose the sludge and microbial supplementation.

In the aerobic tank 20, most of organic matter decomposition, nitrogen, and phosphorus decomposition are performed, and BOD 80-90%, SS 70-80%, T-N 57%, and T-P 60-70% are removed.

In the sedimentation tank 30, the microorganisms excessively ingested in the aerobic tank 20 are stressed, and some elution occurs, and the solid solution is separated and the supernatant is moved to the anaerobic tank 40, and the precipitated sludge is returned to the aerobic tank 20 or the sludge concentration tank 50. Is transferred to the high temperature aerobic reactor 60 is introduced. At this time, if the conveyed amount is based on the amount discharged from the settling tank as 100, the amount returned to the aerobic tank 20 through the 104 conveying path is about 10-50, and the amount conveyed to the high temperature aerobic reaction tank 60 through the 105 conveying path is In 20-50 is suitable.

In the oxygen-free tank 40, sludge microorganisms introduced from the settling tank 30 is returned to the aerobic tank 20 through the 102 conveying path in a state of starvation through denitrification and microbial metabolism.

The sludge thickening tank 50 functions to more efficiently concentrate the sludge introduced from the settling tank 30, and the supernatant water from the sludge thickening tank 50 is joined to the 101 supply line through the 107 conveying path and returned to the aerobic tank 20. do.

The optimum concentration flowing into the high temperature aerobic reactor 60 from the sludge concentration tank 50 is about 2-4% TSS.

An example in which the technical idea of the present application is specifically implemented is an invention completed by confirming that it can be industrially usefully achieved based on the following experimental data.

Experimental Example 1 Design Water Quality and Removal Rate of General A / O and A2O Processes

division inflow Discharge Removal rate BOD 150 mg / l 10 mg / l 93% SS 170 mg / l 10 mg / l 94% T-N 35 mg / l 20 mg / l 43% T-P 5 mg / l 2 mg / l 60% Bounce rate 50% Surplus Sludge Production 2.2 kg / d

Experimental Example 2 Water Quality and Removal Rate When Applying the Treatment Process

division inflow Discharge Removal rate BOD 150 mg / l 10 mg / l 93% SS 170 mg / l 13 mg / l 92% T-N 35 mg / l 21 mg / l 40% T-P 5 mg / l 1 mg / l 80% Bounce rate 50% Surplus Sludge Production 0.42 kg / d Sludge Solubility Rate 40%

From the experimental data, similar results were obtained in the high treatment efficiency of removing nitrogen and phosphorus, but about 81% of sludge was generated in comparison of the amount of sludge generated. The invention was confirmed to have a reduction effect.

As a result of the high-treatment process of the present application through on-site treatment in the same manner as in the experimental example, the material resin results shown in FIG. 4 were obtained.

Also from the data of 4 in upflow filtration tank (10), firstly to remove the solids and organic removal is made can be seen that performing the pre-processing part in the overall reaction, in the process of A / O, A ₂ O process It can be seen that while performing the role of anaerobic tank, the decomposition of organic matter.

In addition, it can be seen that the solids increase in the aeration tank 20 is absolutely dependent on the inflow of solids and the return from the high temperature aerobic reaction tank. The data values show that the sludge solubilization rate is 40 kg / d in the high temperature aerobic reactor. The reactor outflow sludge amount is 24 kg / d, about 40%, and the sludge circulation rate is 20000 mg / l for the high temperature aerobic reactor, and the excess sludge concentration is about 3.3 mg / l.

The sludge reduction rate is proportional to the product of the sludge solubilization rate and the sludge circulation rate, and in the actual operation, the sludge circulation rate, which is easy to operate artificially, is the most important factor.In the high temperature aerobic reactor, the sludge circulation rate is 2-3, and the aerobic tank When the MLSS was 2000-5000 mg / l, the sludge reduction ratio was optimal with 46-92%.

The relationship between sludge reduction rate

Sludge Reduction Rate = k * Sludge Solubilization Rate * Sludge Circulation Rate

k = 1-cell production coefficient in aerobic tank * deoxygenation coefficient can be expressed as

Cell Production Factor = Microbial Amount / BOD Amount

Sludge Reduction Rate = 1-334.2kg / d / 98.85kg / d * 0.06 = 0.8

Sludge solubilization rate (%) = [1-(High temperature aeration tank discharge sludge / high temperature aerobic reactor sludge volume)] * 100

Sludge circulation rate = High temperature aerobic inlet sludge concentration / excess sludge concentration

Therefore, the actual sludge reduction rate (%) is interpreted as an equation of [1-treated process sludge amount / general process generated sludge amount] * 100.

The above descriptions are not data supported by accurate theoretical basis, and are expressed in terms of k value to explain that sludge circulation rate and sludge solubilization rate are important factors in actual operation for sludge reduction. The values are only experimental constants, and the sludge reduction rate represents the ratio of sludge generated from the amount of sludge generated. In actual field operation, it is possible to control only the amount of excess sludge and sludge flowing into the high temperature aerobic tank. Therefore, to find the driving conditions, the general relationship is set and used.

In addition, from the data of FIG. 4, the mass balance flow in the high-temperature aerobic reaction tank was found to have a removal rate of about 64% for BOD, about 40% for SS, about 20% for TN, and about 50% for TP. It can be seen that the sludge is hardly generated at the same time as the efficient water treatment only by adjusting the appropriate solubilization rate and the external transport amount.

In the present invention, when the treated water is introduced at a high concentration, it is possible to adjust the sludge generated in the high temperature aerobic reaction tank, and when the treated water is introduced at a low concentration, the sludge can be adjusted only by the upflow filtration tank and external return.

In the advanced treatment process of the present application, the upflow filtration tank acts as an anaerobic tank to promote effective dissolution, and an anoxic tank is installed at the rear stage of the settling tank, so that an excellent denitrification effect and excessive intake of organic matter when returning to the aeration tank can be performed efficiently. Has the advantage.

Also as an application process in the advanced treatment process The membrane bioreactor (MBR, Membrane Bio Reactor) is characterized in that to increase the treatment efficiency.

Immersion type separation membrane is a well-known technique, which is disclosed in detail in Korean Patent No. 0418859. By incorporating the membrane bioreactor in the advanced treatment process of the present application, the occurrence of sludge swelling and pin floc phenomena, which may occur in a sedimentation basin, is remarkable. It was confirmed that the MLSS of the aerobic tank was maintained at a high concentration of about 6000-15000mg / l, and thus, it was found to be resistant to impact load, improve the reaction speed, and reduce the capacity of the reactor.

In the existing MBR process, when the sludge residence time (SRT) is increased due to high MLSS, the hydraulic retention time (HRT) is shortened and the land area can be reduced. There is a risk of deterioration, disadvantageous from the point of phosphorus removal which is advantageous for nitrification but requires a short SRT, and also requires a separate treatment process for phosphorus removal, and a problem that the denitrification is not easy due to the short HRT. There was, but by the introduction and grafting of the MBR process in the proper position of the high-treatment process of the present application, it is possible to perform the phosphorus removal in the upstream filtration tank during the pretreatment process.

In addition, the MBR tank is installed at the rear end of the aerobic tank and anoxic tank is installed at the rear stage to effectively perform denitrification, and the sludge residence time and the microbial concentration of the MBR reaction tank can be controlled by using a high temperature aerobic tank. Can be applied.

In addition, in preparation for an emergency of an advanced or unpredictable emergency of the advanced treatment process as shown in FIG. 6, an MBR tank may be installed at the rear of the anoxic tank to provide a structure that complements the advanced treatment process of the present application, thereby ensuring perfect water treatment. .

The present invention, in order to solve the problem of the sludge generated by the activated sludge method in the wastewater treatment, in order to smoothly perform the advanced treatment of wastewater while reducing the amount of sludge, a lot of research has been carried out from the 60-70s In the advanced treatment of ATAD process, an oxygen-free tank is installed at the rear stage of sedimentation tank to combine the advantages of OSA process with excellent denitrification and organic decomposition. It also relates to a method that maximizes the effect by saving additional equipment costs and pretreatment. This makes it easy to operate and has the effect of reducing sludge and having a stable water treatment.

Claims (5)

Nitrogen and phosphorus are removed at the same time through the advanced treatment method, which includes a filtration tank 10, an aerobic tank 20, a precipitation tank 30, an anoxic tank 40, a sludge concentration tank 50, and a high temperature aerobic reaction tank 60. In the advanced treatment method for reducing the amount of sludge generated, The filtration tank 10 is provided in an upflow, has a filtration layer inside the upflow filtration tank, suspended solids are deposited by the filtration layer, and a biofilm is formed, so that it is easy to elute the phosphorus by anaerobic reaction at the bottom and the microorganism at the top. Upflow filtration is provided to effect organic decomposition and nitrogen removal; The supernatant liquid corresponding to the inflow of the object to be treated into the upflow filtration tank 10 is transferred to the aerobic tank 20 through the outlet of the upper layer, and the object to be introduced into the aerobic tank is continuously supplied from the air supply unit through the diffuser. Providing a biological treatment using; The treated material that passes through the aerobic tank 20 flows into the settling tank 30, and the sedimentation tank 30 separates the influent from the aerobic tank 20 into sediment sludge and supernatant containing the to-be-processed material and microorganisms by gravity. The supernatant is transferred to the anaerobic tank 40 and the settling sludge is transferred to the concentration tank 50, recycled to the aerobic tank 20, or discharged excess sludge; Anoxic tank 40 is installed at the rear end of the settling tank 30 to remove nitrogen of the introduced sludge and act to continuously suppress sludge generation, while the supernatant is discharged according to the discharge standard or recycled to the aerobic tank 20; The concentrated sludge transferred to the high temperature aerobic reaction tank 60 through the sludge thickening tank 50 is reprocessed and recycled to the aerobic tank 20; Advanced processing method characterized in that it is provided, including. The method of claim 1, The filtration layer of the upflow filtration tank 10, using a crushed stone, or selected from among the media that is easy to attach microorganisms, characterized in that the high treatment method. The method of claim 1, MBR tank at any position in the advanced treatment method, including the upflow filtration tank 10, the aerobic tank 20, the settling tank 30, an anoxic tank 40, the sludge concentration tank 50, and a high temperature aerobic reaction tank (60). Advanced processing method, characterized in that provided to increase the processing efficiency by additional installation. The method of claim 1, The MBR tank at the rear end of the anoxic tank in the advanced treatment method, including the upflow filtration tank 10, the aerobic tank 20, the settling tank 30, the anoxic tank 40, the sludge concentration tank 50 and the high temperature aerobic reaction tank (60). Advanced processing method, characterized in that provided to drive the installation. The method of claim 4, wherein Advanced processing method characterized in that to operate by maintaining the MLSS of the aerobic tank in the concentration range of 6000-15000mg / l when installing and operating the MBR tank at the rear end of the anoxic tank of the advanced processing method.

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