KR20100102818A - Advanced wastewater treatment apparatus for water reuse with sludge reduction in the process and wastewater treatment method using the same - Google Patents

Abstract

PURPOSE: An advanced wastewater processing apparatus for reducing excessive sludge and generating recycled water is provided to obtain the stable quality of processed water by eliminating residual floating materials. CONSTITUTION: A bio-reactive bath(2) stores wastewater and implements intermittence aeration for cultivating microorganism into a precipitation state. The precipitated microorganism is separated from the wastewater. A precipitate bath(4) stores the wastewater from the bio-reactive bath and precipitates floating materials by gravity-precipitation. The precipitated floating materials are utilized as return activated sludge and the wastewater without the sludge is drained. A high-rate coagulation-precipitation unit(6) introduces a coagulation agent into the wastewater without the sludge. Through a chemical coagulation process, recycled water is generated by eliminating phosphorus contents and remained floating materials.

Description

Advanced wastewater treatment apparatus for water reuse with sludge reduction in the process and wastewater treatment method using the same}

The present invention relates to an advanced biological treatment apparatus and method of sewage water, and more particularly, to reduce the excess sludge remaining in the sewage sludge generated during the sewage treatment process to minimize, and to remove phosphorus and nitrogen as organic matter and nutrients in the target raw water. The present invention relates to an ultra-high sewage treatment apparatus and a method capable of reducing surplus sludge in a process and producing recycled water, which maximizes the use of, and utilizes the supernatant water after the secondary sedimentation tank as reused water.

In general, sewage treatment has been rapidly developed with the development of activated sludge process using microorganisms, and is mainly operated for the purpose of removing organic matter and suspended solids. At present, a variety of variations are being developed as the process is advanced to remove nitrogen and phosphorus. Referring to the principles of the biological advanced treatment process of development, nitrogen removal is ammonia (NH ₄ ⁺⁾ nitrogen dioxide (NO ₂ ^-) by nitrifying micro-organisms or nitrate nitrogen (NO ₃ ^-) after the nitrification process of oxidation, the denitrification It is made by exhausting to nitrogen (N ₂ ) gas through, phosphorus removal is carried out by ingesting phosphorus eluted under anaerobic conditions by excessive intake of phosphorus by microorganisms under aerobic conditions, and then removing sludge. Methods for removing nitrogen and phosphorus using this principle include A ₂ O, SBR, modified Bardenpho, VIP (Virginia Initiative Plant), and the University of Cape Town (UCT) process.

In order to successfully operate such biological advanced treatment processes, a bioreactor with anaerobic, anaerobic and aerobic conditions must be configured. In anaerobic and anaerobic conditions, sufficient carbon sources are required for phosphorus release and denitrification, and high levels of technical know-how are required, such as the discharge of excess amounts of phosphorus ingested sludge. In addition, as shown in FIG. 1, a facility for concentrating, dehydrating, and storing the excess sludge discharged from the process, and final disposal of incineration, landfill, etc., is required.

Excess sludge from sewage treatment plants is a proliferator of microorganisms that played a major role in removing contaminants such as organic matter during the treatment process. Most of the efforts to reduce sewage sludge produced by sewage treatment have been carried out from the point of view of post management using digestion, incineration, ozone treatment, ball mill, and ultrasonic waves. As a more proactive management system, research for reducing sludge in the process has been called for in recent years as well as the need for systematic research. At present, as an active alternative to sludge disposal and treatment, attempts have been actively made to suppress sludge generation in the treatment process or to minimize sludge discharged out of the system by physicochemically treating surplus sludge and introducing it back into the water treatment system. The Oxic-Settling-Anaerobic (OSA) process, which is a variation of the activated sludge process, also leads to the reduction of excess sludge discharged out of the system.

The OSA process has been encouraging that sludge reduction has been performed in the process, but it has a disadvantage in that the accumulated nutrients inside the process are highly processed due to the death and decomposition due to the long residence time of the microorganism. In other words, organic matter free from microorganisms is used as a substrate for active microorganisms, which is advantageous for treatment, while nutrients nitrogen and phosphorus show only limited treatment efficiency when external environmental factors related to treatment are not satisfied. Increasing the load on the reaction system poses a potential problem of not meeting legal regulations.

The sewage treatment processes have been operated for the purpose of improving the removal efficiency to reduce the pollutant load in the water system, but recently, the use of sewage reused water is gradually expanding as a new alternative water resource securing the water shortage. . In particular, sewage recycled water is expected to induce positive results in terms of water use as well as energy. Therefore, it is time for ultra-high sewage treatment technology to secure stable water quality.

Therefore, the present invention has been proposed to solve the above problems and to meet the requirements, induction of the reduction of excess sludge by installing an anaerobic tank in the sludge conveying line in the active sludge process, which is a conventional sewage treatment process, Maximizes the removal of nitrogen from the nutrients in the raw water by operating the intermittent aeration tank, and reduces the excess sludge in the process and produces recycled water by applying a high-speed flocculation sedimentation process, which is a chemical flocculation process, to the overflow water of the bioreactor. It is an object of the present invention to provide such an ultra-high sewage treatment apparatus and method.

In order to achieve the above object, the present invention provides a bioreactor for culturing and discharging microorganisms in a state capable of sedimentation separation by intermittently giving up the wastewater introduced from the outside in the biological reaction tank; A sedimentation tank for storing solid wastewater containing activated sludge discharged from the bioreactor for solid-liquid separation of sludge by gravity sedimentation, and supernatant discharged from the sludge; A high-speed coagulation sedimentation apparatus for storing supernatant flowed from the sedimentation tank, and producing recycled water by performing a chemical coagulation process for removing phosphorus and residual particles by injecting a coagulant into the supernatant water; An anaerobic tank receiving sludge precipitated from the settling tank and inducing endogenous breathing and killing of microorganisms; And it provides an ultra-high sewage treatment apparatus capable of reducing the excess sludge in the process and the production of reused water, including a return line for returning the sludge containing the starvation microorganisms in the anaerobic tank to the bioreactor.

The bioreactor is an intermittent aeration tank capable of changing the environment to an aerobic state and an anaerobic state through the intermittent aeration cycle operation.

In addition, the present invention is the first step of introducing the wastewater containing organic matter and nutrients from the outside into the bioreactor and the intermittent aeration to remove the nitrogen components of the organic matter and nutrients, and then to make a solid-liquid separation state and discharge; A second step of introducing the sewage water from the bioreactor into the sedimentation tank to precipitate suspended matter from the sewage water containing activated sludge through gravity sedimentation, and the supernatant water overflowed; A third step of automatically injecting an optimum flocculant to minimize the amount of flocculating sludge in the supernatant flowed from the sedimentation tank to chemically remove residual suspended matter and phosphorus component to produce stable water reused water; A fourth step of introducing the sludge settled in the settling tank into the anaerobic tank through the sludge conveying pump and maintaining the killing and endogenous breathing through limiting the substrate of the bacteria; The sludge containing the microorganisms starved in the anaerobic tank is brought into a bioreactor having a relatively high substrate / microorganism (S _o / X _o ) ratio through a return line to secure microbial concentrations necessary for basic sewage treatment. At the same time, most of the microorganisms secured for sewage treatment are used for metabolism to reduce excess sludge, and intermittent aeration of the bioreactor is carried out to convert the bioreactor to anoxic conditions, thereby reducing nitrate nitrogen in aerobic conditions. Provided is an ultra-high sewage treatment method capable of reducing excess sludge in a process and producing recycled water, including a fifth step of reducing nitrogen gas.

As described above, the present invention has the following effects.

First, it is possible to remove nitrogen from nutrients caused by inflow water and sludge reduction process by giving aeration and anoxic conditions to the bioreactor.

Second, active sludge reduction is possible by minimizing surplus sludge generated in the process by inducing endogenous and starvation of microorganisms in the anaerobic tank.

Third, by performing the fast flocculation sedimentation to remove the residues and phosphorus contained in the biological treatment water to ensure a stable treatment water quality can be recycled water can be used as alternative water resources.

Fourth, the simple configuration and easy operation of the bioreactor can maximize the applicability of the advanced sewage treatment improvement work of existing sewage treatment plants, and facilitate the technical approach of site operators. Since the improvement of sewage treatment facilities has been actively progressed recently, it is possible to reduce the cost of improvement work by minimizing the renovation work of sewage treatment facilities and actively utilizing existing facilities.

Fifth, in terms of economics, not only can the sludge treatment and disposal costs, which account for about 60% of the operating cost of sewage treatment plants, be drastically lowered, but also the operating costs of sewage treatment plants can be reduced by reducing the abandonment cost, which consumes most of the power in operating the facility. You can. Recycled water production can also generate additional value for water demand.

Hereinafter, with reference to the accompanying Figure 2 will be described an embodiment of the present invention;

The ultra-high sewage treatment apparatus capable of reducing excess sludge in the process and producing recycled water according to the present invention maximizes the removal of nutrients in the reaction tank due to the reduction of sewage sludge, and reduces surplus sludge, thereby drastically reducing the operating cost of the sewage treatment plant. In addition, it is possible to produce recycled water through ultra-high processing.

An embodiment of the present invention is a system adapted to induce excess sludge reduction by using the Oxic Settling Anaerobic (OSA) process proposed as a variation of the activated sludge process.

That is, the present invention, as shown in Figure 2, the bioreactor (2) for storing the inflow through the primary sedimentation basin (not shown) while performing intermittent aeration; The wastewater containing the activated sludge discharged from the bioreactor 2 is stored to solidify the suspended solids by gravity sedimentation, and the total amount of sludge is used as the returning sludge according to the normal return rate (0.5 to 2.0Q), A settling tank 4 for discharging the sludge in case of deformation or operation problems, and discharging the supernatant; A high-speed flocculation settling apparatus 6 for storing the supernatant water overflowed from the settling tank 4 and performing reuse of chemicals to remove phosphorus and residual particles contained in the supernatant water to produce reused water; A sludge conveying pump 8 for conveying the conveying sludge discharged from the settling tank 4 to an anaerobic tank which will be described later; An anaerobic tank (10) which receives the conveying sludge through the sludge conveying pump (8) and induces endogenous respiration and death of microorganisms in an anaerobic state; And a conveying line 12 for conveying sludge containing the starvation microorganisms to the bioreactor 2 in the anaerobic tank 10.

In the present invention, the high-speed flocculation settling apparatus 6 includes a high-speed flocculation settling tank 20 for carrying out a chemical flocculation process by storing supernatant water; A coagulant storage tank (22) for storing a coagulant for input into the high speed flocculation settling tank (20); A coagulant injection pump 24 for automatically injecting a coagulant from the coagulant storage tank 22 to the high-speed flocculation settling tank 20; An alkaline supplement medicine storage tank 26 for storing an alkali supplement medicine to be used for reducing phosphorus removal efficiency in the high speed flocculation settling tank 20; And an alkalinity medicine injection pump 28 for automatically injecting the alkalinity supplement medicine from the alkalinity supplement medicine storage tank 26 to the high speed flocculation sedimentation device 6.

Reference numeral 29 denotes a coagulated sludge discharge pump.

On the other hand, when the flocculant is injected, the pH is in the acidic range, thereby reducing the chemical coagulation effect. Therefore, in the present invention, in order to meet the reaction conditions in the neutral range when the pH is lowered according to the reaction, a pH meter 30 is installed on the top of the chemical injection pump 28 of the high-speed flocculation sedimentation device, and an alkali supplemental medicine injection pump ( 28) can be automatically linked with. That is, when the pH is out of the proper pH (meter) (30) to deliver a signal to the pump to obtain the optimized aggregation effect by the automatic injection of the drug.

In addition, the anaerobic tank 10 has an electrical conductivity measuring device 32 for monitoring the endogenous and starvation induction of microorganisms; And an ORP meter 34 for monitoring the endogenous and starvation induction of microorganisms in the anaerobic tank 10.

Here, ORP means redox potential as Oxidation-Reduction Potential. Maintaining anaerobic conditions is the key for anaerobic tanks operated for sludge reduction. ORP values are used to monitor anaerobic conditions. In general, the ORP range for anaerobic conditions is -100 to -300 mV. In addition, the conductivity meter can be used as a reference value for detecting the sludge loss by detecting the ionic substances released into the reaction tank due to the disintegration of microorganisms in addition to the starvation of the anaerobic tank. In other words, the relatively high electrical conductivity means that the killing of microorganisms is increased.

In the embodiment of the present invention, the bioreactor 2 performs intermittent aeration to make an aerobic state to meet aerobic conditions, and in the state where aeration is stopped, an intermittent anoxic state to meet anoxic conditions. I give up. That is, the bioreactor 2 is installed on the floor to supply external air and a timer for supplying external air, and a timer for controlling the intermittent aeration cycle time of the acid pipe 36 is installed outside the bioreactor 2 An intermittent aeration device 35 including a 38; In the anoxic condition is provided with an agitator 40 for performing the stirring of the bioreactor 2 performs an intermittent aeration function.

In the embodiment of the present invention, the timer 38 is set to perform abandon operation at a period of 30 to 60 minutes.

The bioreactor 2 having the above-described structure ingests contaminants from the sewage water initially introduced by the intermittent aeration cycle, makes the sedimentation possible, and discharges the sedimentation tank 4. In the future, continual intermittent aeration will create an aerobic condition for nitrification and anoxic conditions that are advantageous for denitrification. By induction, nitrogen removal is performed with sludge reduction. That is, the microorganisms of the anaerobic tank 10 introduced into the bioreactor 2 with relatively high substrate / microbial (S _o / X _o ) ratio are used to maintain basic sewage treatment efficiency and at the same time, most of the energy It is used for metabolism to minimize the production of excess sludge.

It describes the high sewage treatment method according to the invention configured as described above.

Raw sewage water introduced from outside is stored in the primary sedimentation basin to physically remove suspended solids having good sedimentation (not shown). Then, intermittent aeration is performed in the bioreactor 2 with respect to the primary treated water discharged from the primary sedimentation basin to make the solid-liquid separation possible and then discharged to the sedimentation tank 4. In the settling tank (4), the sediment is precipitated from the sewage water containing activated sludge through gravity settling, and the supernatant is overflowed.

The supernatant flowed from the settling tank 4 is stored in the high speed flocculation settling tank 20, and the coagulant stored in the flocculant storage tank 22 is introduced into the high speed flocculation settling tank 20 through a coagulant injection pump 24 to chemically. The flocculation process removes residual particles and phosphorus to produce recycled water. The sludge aggregated in the high speed flocculation settling tank 20 is carried out to the outside by the operation of the sludge discharging pump 29.

In addition, the sludge settled in the settling tank 4 is introduced into the anaerobic tank 10 in the total amount in accordance with the normal return rate through the sludge conveying pump (8). At this time, the sludge is returned while monitoring the endogenous and starvation of microorganisms in the anaerobic tank 10 through the conductivity meter 32 and the ORP measuring instrument 34, and the sludge concentration in the anaerobic tank 10 is changeable in a controllable range. In case of out of operation or problems in operation, a certain amount of sludge is taken out in consideration of sludge concentration and treatment efficiency.

The anaerobic tank 10 into which the returned sludge is introduced not only maintains killing and endogenous breathing through the restriction of bacteria, but also minimizes growth, activity and proliferation by maintaining a low active state according to residence time (SRT and HRT). Solution Controls basal metabolism.

Sludge containing microorganisms starved in the anaerobic tank 10 through the above operation is a bioreactor (2) having a relatively high substrate / microorganism (S _o / X _o ) ratio is formed through the return line (12) Flows into. The microorganisms brought into the bioreactor 2 from the anaerobic tank 10 are supplemented with nutrients by intermittent aeration to secure the concentration of microorganisms necessary for basic sewage treatment. At this time, the concentration of microorganisms secured for sewage treatment is mostly used for material metabolism rather than energy propagation, thereby minimizing the production of excess sludge, thereby inducing the reduction of excess sludge. In addition, the intermittent aeration operation of the bioreactor 2 is performed to convert the bioreactor 2 to anoxic conditions, thereby reducing nitrogen nitrate to nitrogen gas to release nitrogen into the air.

Figure 3 is a correlation graph of the DO concentration according to the MLSS for the intermittent periodic selection of the bioreactor, which is the main part of the present invention, Figure 4 is the sludge production and the denitrification rate (SDNR) according to the operating conditions of the intermittent aeration cycle of the bioreactor Fig. 5 is a graph showing the trend, and shows the treatment efficiency and water quality of the regeneration water by chemical aggregation.

First, Figure 3 in the present invention, the conversion of the bioreactor 2 to the intermittent aeration tank means the determination of the operation cycle of the aeration device installed for the purpose of oxygen supply. Since the concentration of oxygen demand (DO) is affected by the temperature, MLSS, etc., it is necessary to consider the conditions according to the external environment, but in the experiment of the present invention, while maintaining the temperature constant, the DO profile that changes with time using MLSS is a factor. I found out. The pH ranged from 6.8 to 7.2 and the temperature was about 18 conditions. Anaerobic conditions of the anaerobic tank (10) were based on the intermittent cycle selection criteria based on the time when the DO concentration reaches 0.1 ~ 0.2 mg / L. In the experiment, the change of MLSS of the reactor was performed for MLSS 1,800 mg / L and the maximum value of 2,500 mg / L, and the results are shown in FIG. 3.

As shown in the graph of FIG. 3, when the MLSS concentration was maintained at 2,500 mg / L, the time for reaching the anaerobic condition was about 10 minutes, and when the MLSS was maintained at the concentration of 1,800 mg / L, it was required about 46 minutes. . Based on the results, the ratio of aeration / aeration ratio and aeration duration of the mode was determined, and the determined experimental conditions are shown in Table 1 below.

Table 1

   ISA Process run     Time cycle Ratio (On / Off) (min)
Mode
Run 2-1 40 30: 10 Run 2-2 60 30: 30 Run 2-3 90 60: 30 Run 2-4 120 60: 60

Figure 4 shows the sludge production according to the aeration cycle in the process of the present invention by the operating conditions of SDNR (non-nitrogen ratio). Run 2-1, run 2-2, and run 2-3 with no aeration time of less than 30 minutes show no significant SDNR improvement, while run 2-4 with a 60 minute aeration time shows significant improvement in denitrification. Appeared. P _x which means sludge production _{. vss} is not affected by changes in operating conditions because it does not show any significant change.

In view of the above results, in the embodiment of the present invention, it was found through experiments that the intermittent aeration: aeration cycle time in the bioreactor 2 is preferably operated at a timing of 30 to 60 minutes: 10 to 60 minutes. Optimized abandonment: The aeration time was 60: 60 minutes.

In this way, the intermittent aeration operation of the bioreactor 2 enables the preliminary reduction of excess sludge, and can reduce the aeration cost consumed by most of the power costs in operating the facility.

Figure 5 shows the phosphorus removal efficiency and treatment water quality according to the flocculant concentration injected in the high-speed flocculation apparatus to secure stable water quality for reused water production. The injection concentration of the PAC used as the flocculant under the optimum flocculation conditions is about 50. When injected at ~ 100 mg / L, it was found that reasonable optimal treatment water quality could be obtained.

As a result, the recycled water produced in this process satisfies the recycled water recommendation criteria and can be used as an alternative water resource.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill.

1 is a general sewage treatment plant process diagram for performing advanced biological wastewater treatment.

Figure 2 is a schematic process diagram showing an embodiment of an ultra-high sewage treatment apparatus capable of reducing the excess sludge in the process and the production of recycled water according to the present invention.

Figure 3 is a correlation graph of the hourly DO concentration according to MLSS for the intermittent periodic selection of the main bioreactor of the present invention.

4 is a graph showing the sludge production and the specific denitrification rate (SDNR) according to the operating conditions according to the intermittent aeration cycle of the bioreactor.

Figure 5 is a graph showing the phosphorus removal efficiency and treatment water quality according to the flocculant concentration injected into the high-speed flocculation settler for the production of reused water of stable water quality.

* Explanation of symbols for the main parts of the drawings

2: bioreactor 4: precipitation tank

6: high speed flocculation equipment 8: sludge conveying pump

10: anaerobic tank 12: return line

20: high speed flocculation tank 22: flocculant storage tank

24: Coagulant injection pump 26: Alkaline supplement medicine storage tank

28: alkaline chemical injection pump 29: coagulated sludge discharge pump

30: pH meta 32: electrical conductivity measuring device

34: ORP measuring instrument 35: intermittent aeration device

36: diffuser 38: timer

Claims (6)

A bioreactor for storing microbial cells in a state in which sedimentation and separation are possible by storing wastewater introduced from the outside but intermittently giving up; A sedimentation tank for storing sewage wastewater containing activated sludge discharged from the bioreactor for sedimentation by gravity sedimentation, utilizing the total amount of the suspended solids as a return sludge, and discharging the supernatant; A high speed flocculation sedimentation apparatus for inputting a flocculant into the supernatant flowed from the sedimentation tank and removing the phosphorus component and the remaining residual particles through a chemical flocculation process to produce reused water: An anaerobic tank receiving return sludge from the settling tank and inducing endogenous breathing and killing of microorganisms; And Return line for returning sludge containing starvation microorganisms to the bioreactor in the anaerobic tank Ultra-high sewage treatment apparatus capable of reducing the excess sludge in the process and producing reused water. The method of claim 1, The bioreactor is An intermittent aeration device for enabling an environment change to an aerobic state and an anaerobic state through an intermittent aeration cycle operation; And Underwater agitator for agitating the bioreactor under anoxic conditions Ultra-high sewage treatment apparatus capable of reducing the excess sludge in the process and producing reused water further comprising. The method of claim 2, The intermittent aeration device An diffuser installed at the bottom of the bioreactor to supply external air for aeration; And Installed outside the bioreactor, timer for adjusting the intermittent aeration cycle of the diffuser Ultra-high sewage treatment apparatus capable of reducing the excess sludge in the process and producing reused water. The method of claim 1, The high speed flocculation sedimentation device A fast flocculation settling tank for carrying out chemical flocculation process by storing supernatant water; A coagulant storage tank for storing a coagulant for input into the high speed flocculation settling tank; A coagulant injection pump for automatically injecting a coagulant from the coagulant storage tank to a high speed flocculation settling tank; An alkaline supplement medicine storage tank storing an alkali supplement supplement drug to be used for reducing phosphorus removal efficiency in the high-speed flocculation settling tank; An alkaline medicine injection pump for automatically injecting an alkaline supplement medicine from the alkali supplement medicine storage tank to a high speed flocculation settling device; And When the alkali is also connected to the drug injection pump and automatically interlocked with the pH to allow the drug to be automatically injected into the drug injection pump side when the alkali is out of the proper pH (meter) Ultra-high sewage treatment apparatus capable of reducing the excess sludge in the process and producing reused water. A first step of introducing a wastewater containing organic matter and nutrients from the outside into a bioreactor and intermittently giving up to remove nitrogen from organic matter and nutrients and then making solid-liquid separation possible; A second step of introducing the sewage water from the bioreactor into the sedimentation tank to precipitate suspended matter from the sewage water containing activated sludge through gravity sedimentation, and the supernatant water overflowed; A third step of automatically injecting an optimum flocculant for minimizing the amount of flocculating sludge generated in the supernatant flowed from the settling tank in the settling tank to chemically remove residual suspended matter and phosphorus component to produce stable water reused water; A fourth step of introducing the total amount of suspended sludge deposited in the settling tank into the anaerobic tank through a sludge conveying pump and maintaining death and endogenous breathing through limiting the substrate of bacteria; And The sludge containing the microorganisms starved in the anaerobic tank is brought into a bioreactor having a relatively high substrate / microorganism (S _o / X _o ) ratio through a return line to secure microbial concentrations necessary for basic sewage treatment. At the same time, most of the microorganisms secured for sewage treatment are used for metabolism to reduce excess sludge, and intermittent aeration of the bioreactor is carried out to convert the bioreactor to anoxic conditions to reduce nitrate nitrogen to nitrogen gas. 5th step Ultra-high sewage treatment apparatus capable of reducing the excess sludge in the process and producing reused water. The method of claim 5, Intermittent aeration in the fifth step: aeration cycle time is 30 ~ 60: ultra-high sewage treatment apparatus capable of reducing the excess sludge in the process and the production of recycled water, characterized in that 10 to 60.

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