KR100659034B1 - Sludge treating apparatus for improvement of the sludge settlability in a rectangular settling tank - Google Patents

Abstract

The present invention discloses a sludge treatment apparatus of a final sedimentation basin for improving sludge settling in a biological sewage plant.

The present invention includes a first hopper (21) to collect the sludge in the region between the treated water inlet and the middle portion of the final sedimentation basin 20; A second hopper 22 for collecting the settling sludge in the region between the middle portion of the final settling basin 20 and the supernatant outflow portion; Sludge conveying means (24) connected to the first hopper (21) to convey the total amount of the settling sludge collected in the first hopper (21) to the biological reaction tank (10); The sludge collected in the second hopper 22 connected to the second hopper 22 may be returned to the bioreactor 10 in its entirety or may be drawn out for disposal, or a certain amount may be returned and excess sludge may be drawn out for disposal. It is characterized by consisting of; conveying sludge amount adjusting means 25 for selectively performing the operation.

According to the present invention, the sludge microorganisms having poor sedimentation are collected at the final sedimentation basin and selectively disposed of, so that the microorganisms having poor sedimentation can be accumulated and proliferated in the water treatment process. You can.

Sewage / wastewater treatment, bioreactor, final sedimentation basin, sludge, sedimentation, return / disposal

Description

Sludge treating apparatus for improvement of the sludge settlability in a rectangular settling tank}

1 is a view showing a rectangular sedimentation basin facility, which is a method of designing, constructing and operating a secondary sedimentation basin in a conventional activated sludge process and other biological reactors.

2 is a view showing a sludge treatment system of a rectangular sedimentation basin according to the present invention.

3 is a view showing a typical sludge blanket profile observed in the rectangular sedimentation basin according to the present invention.

Figure 4 shows a method of determining the optimum installation position of the hopper in a rectangular sedimentation basin according to the present invention

<Description of Symbols for Main Parts of Drawings>

10: biological reaction tank 20: final sedimentation basin

21: Hopper 1 22: Hopper 2

23: bottom 24: sludge conveying means

25: conveying sludge amount adjusting means

The present invention relates to a sludge treatment apparatus of a rectangular final sedimentation basin in order to prevent a decrease in treatment efficiency due to deterioration of sludge in biological sewage / wastewater treatment plants by activated sludge method. The final sedimentation basin to improve the sludge sedimentation ability to collect and selectively dispose of these poorly settled microorganisms by blocking the chance of accumulation and propagation in the water treatment process. To a sludge treatment apparatus.

As is well known, the activated sludge process is a process of removing organic substances in wastewater through the process of respiration and synthesis of microorganisms by propagating microorganisms as organic substrates in sewage or wastewater (hereinafter abbreviated as "wastewater") under aerobic conditions. .

In other words, the wastewater purification by the activated sludge process is a water treatment method in which the activated sludge absorbs and oxidizes organic matter in the process of activating and growing organic matter in the wastewater as a nutrient source in an appropriate dissolved oxygen state.

The four major facilities used in this activated sludge process are bioreactors (aeration tanks) with oxygen supply, final clarifiers as solid-liquid separators, return sludge facilities and waste sludge discharge facilities ( It consists of waste sludge facilities.

In this facility, the first settled sewage and return sludge are injected and mixed by acid or mechanical aeration, and the air is injected evenly over the entire area, while adsorption, flocculation, and oxidation occur during the aeration time. Organics are converted to mixed liquor suspended solids (MLSS).

That is, when the first settled sewage water enters the bioreactor together with the reacted sludge, the activated sludge in the reactor adsorbs the suspended solids contained in the sewage water, and the organic matter adsorbed while staying in the reactor is hydrolyzed and discharged to the outlet. Most of the time it gets oxidized.

As above, the activated sludge reacted for a certain residence time in the bioreactor is sent to the final sedimentation basin.

In the final sedimentation basin sludge and the supernatant is separated as shown in Figure 1 and the supernatant is discharged through the weir, the sludge collected in the lower part of the sedimentation basin is returned by a conveying facility and mixed with the inflow wastewater, and flowed back into the bioreactor, Excess sludge is drawn through the waste sludge plant and disposed of.

The main role of the final sedimentation basin is broadly divided into three categories: first sludge clarification function, second sludge thickening function, and third sludge storage function.

The first function, the sludge settling function, takes place at the top of the settling basin.

This sedimentation function refers to the sedimentation of individual sludge particles separated by the turbulent flow from the sludge flocs or the main stream of sludge introduced into the final settling basin in the bioreactor.

The sedimentation function of these activated sludge settler basins is of great importance for the satisfactory concentration of suspended solids in the effluent or effluent and the resulting BOD ₅ satisfaction.

The sludge thickening function, the second function of the final settling basin, occurs mainly at the bottom of the settling basin.

Failure to concentrate due to improper settling and operation of the sedimentation basin leads to a wash-out problem of high concentrations of sludge above the discharge standard of 10 mg / L in the effluent. As this will adversely affect the overall sludge process, it is essential for the smooth operation of the waste sludge facility and subsequent sludge treatment facilities as well as maintaining the appropriate MLSS concentration in the bioreactor.

Sludge storage, the third function of the final sedimentation basin, is a function to cope with the temporary occurrence of hydraulic overloads in urban sewage treatment plants, often with combined sewer during heavy rains.

On the other hand, the microorganism is composed of microorganisms that are easily precipitated according to the operating conditions, and microorganisms that inhibit the solid-liquid separation.

Most of the microorganisms that inhibit the solid-liquid separation in the sedimentation basin are filamentous microorganisms. Actually, the excess presence of these filaments causes sludge bulking problems, which eventually paralyzes the sedimentation, concentration, and storage functions of the sedimentation basin. Significantly lowers.

There are many factors that cause bulking, but there are typically low dissolved oxygen concentrations, nutrient imbalances, low pH, and low F / M boiling.

At present, the method for controlling filamentous fungi in previously developed sludges is as follows. First, the method of changing the operating environment in the bioreactor, the second method of selective killing of filamentous fungi using chlorine or other oxidants in the return sludge line, and the third selector A number of studies have been conducted on how to induce selection of filamentous fungi using competition between filamentous fungi and the normal microbial diet. Among them, a method using a selector is actually installed in a field in the United States or Europe, and its effect is verified.

However, the filamentous fungi control method as described above has a disadvantage in that it requires a high operating technique, continuous observation and complicated management, and requires a separate treatment cost.

Another function of the final sedimentation basin that can solve this disadvantage, there is the selective separation of microorganisms introduced into the sedimentation basin in the bioreactor.

A representative role of the selective separation of microorganisms is to suppress the occurrence of scum problems in the sedimentation basin. For example, Actinomycete, a soil microorganism that can be observed in sedimentation basins, does not have a chance of accumulating growth in the process of activated sludge process, but it is separated from other sludge microorganisms and rises to the surface and discharges with the effluent. The selective separation of microorganisms may play a role in suppressing the occurrence of scum problems.

As a conventional technology using the concept of the above-described microbial selective separation function, there is a domestic patent publication No. 2000-0058322.

This prior art proposes a method of designing and operating a secondary sedimentation basin to prevent a decrease in treatment efficiency due to deterioration of sludge sedimentation in biological sewage and wastewater treatment plants, and in a sewage treatment plant or wastewater treatment plant using activated sludge and its variations. A secondary settling basin is installed to enable parallel or series operation with respect to the bioreactor, but provides a technique by appropriately combining parallel operation and serial operation.

The prior art that provides such a technology is a simple physical operation instead of using complex bio-chemical methods to reduce the treatment efficiency caused by sludge deterioration of sludge, which is the biggest obstacle in operation in a sewage or wastewater treatment plant. By solving this problem, convenience and cost reduction in operation and maintenance are attempted.

However, in order to operate the sedimentation basin in parallel or in series, the above-mentioned prior art should have a facility for operating two sedimentation basins in a group, so that a large land area is required and it is difficult to miniaturize the treatment plant. There was a problem that the construction cost is enormous.

In addition, when operating in a parallel flow and converted to a serial flow, the residence time is not only long, but also because the flow of the treated water during the conversion is severely flowed, there was a problem of inhibiting the sedimentation of sludge to reduce the precipitation efficiency.

The present invention has been made to solve the problems of the conventional secondary sedimentation basin, namely, the final sedimentation basin in the facility and operation method, the object of the present invention using a selective separation function according to the settling rate of microorganisms observed in the sedimentation basin In order to control the overgrowth of filamentous fungi that prevents efficient settling operation, by blocking the opportunity for microorganisms to accumulate and proliferate in the water treatment process by simple physical manipulation method, only sludge microorganisms with poor sedimentation can be collected and finally disposed of in the final settling basin. In addition, the present invention provides a sludge treatment apparatus for the final sedimentation basin to improve the sludge sedimentation ability to maintain the overall sludge sedimentation well.

The sludge treatment apparatus of the final sedimentation basin for improving the sludge settling properties of the present invention for achieving the above object, the supernatant outflow portion in the treated water inlet portion in which the treated water passed through the biological reaction tank during the biological water treatment process by the activated sludge method A sludge treatment apparatus of a final sedimentation basin configured to convey a set amount of sediment sludge of a rectangular final sedimentation basin which is designed to have a bottom surface of an uphill slope to the bioreactor, and to draw and discard excess sludge. A first hopper installed below the bottom surface positioned at the lower portion to collect the settling sludge in the region between the treated water inlet and the middle part; A second hopper installed below the bottom surface in the middle portion of the final clarifier to collect the sludge in the region between the middle portion and the supernatant outlet portion; Sludge conveying means connected with the first hopper to convey the total amount of the settling sludge collected in the first hopper to the bioreactor; Transfer sludge amount connected to the second hopper to selectively carry out the entire amount of the sludge collected in the second hopper to the biological reaction tank or to draw the entire amount of waste sludge, or to return a certain amount and to draw and discard the excess sludge Control means; consisting of the basic features of the technical configuration.

According to the present invention having the above characteristics, it is divided into sludge with good sedimentation and sludge with poor sedimentation in one sedimentation basin only by installing an additional hopper in a single sedimentation basin for sludge conveyance and disposal. Good sludge is returned to the bioreactor for full use, and sludge with poor sedimentation is drawn out and disposed of in its entirety or only the minimum required amount is returned to the bioreactor.

Therefore, according to the present invention, the sludge having good sedimentability is selected and conveyed through a simple physical operation in a single sedimentation basin, not only having excellent economic efficiency, but also accumulating only sludge having good aeration capacity and sedimentability during the overall water treatment process by the activated sludge method. As it proliferates, the aeration efficiency of the biological reaction tank as well as the sludge settling property of the sedimentation basin are continuously maintained and improved.

Hereinafter, the technical configuration of the present invention will be described in detail with reference to the accompanying drawings of FIGS. 2 to 4 according to an embodiment of the present invention.

The sludge treatment apparatus of the final sedimentation basin according to the present invention will be described as follows.

The sludge treatment system of the present invention is applied to a rectangular sedimentation basin.

In the case of a rectangular sedimentation basin, the sedimentation pattern varies depending on the length of the final effluent from the point where the activated sludge (MLSS) is introduced. The relatively easy to settle particles are precipitated at the beginning of the inflow. Settles at a point far away (away).

In other words, the characteristics of the sedimentation depend on the size of the sedimentation basin, the size of the microbial floc and the type of microorganisms introduced. The larger the size of the floc, the easier it is to settle because the specific gravity of the sludge increases. While microorganisms in the form are easy to precipitate, smaller flocs are more difficult to settle, and in the case of filamentous fungi, precipitation is not easy because the surface area is relatively large.

Due to the characteristics of the rectangular sedimentation basin, the sludge that precipitates in the outflow part farthest from the sedimentation inlet part is the case of fine floc with poor sedimentation, and the sludge can be improved by disposing rather than returning it to the bioreactor. .

Therefore, the core technology of the present invention is to separate two sludge hoppers into a rectangular sedimentation basin in order to improve the overall sedimentability by returning the sludge having good sedimentation to the bioreactor and discarding the sludge having relatively poor sedimentation. It is.

That is, in the present invention, the main technical matter is to additionally install a sludge collection hopper at an appropriate position at the bottom of the rectangular sedimentation basin, and separately collect and dispose only sludge having poor sedimentation in the hopper.

In order to realize this, the present invention, as shown in Figure 2, during the biological water treatment process by the activated sludge method in the treated water inflow portion flowing through the bioreactor 10 inflow from the inlet to the supernatant outflow portion toward the inclined bottom surface ( 23. A sludge treatment apparatus of a final sedimentation basin configured to convey a set amount of settling sludge of the rectangular final sedimentation basin 20 to the bioreactor 10 and to draw out and discard the excess sludge, wherein the hopper collecting the sludge is provided. Separately installed in two places, such as the hopper 21 and the second hopper 22, the sludge collected by the separated first hopper 21 and the second hopper 22 to be returned to the biological reactor (10) or discarded Perform work selectively.

The first hopper 21 is installed below the bottom surface 23 located below the treated water inlet part of the final settler 20 to collect the sludge in the region between the treated water inlet part and the middle part.

The settling sludge collected in the first hopper 21 is conveyed to the biological reaction tank 10 through the sludge conveying means 24 connected to the first hopper 21.

The second hopper 22 is installed below the bottom surface 23 in the middle portion of the final settling basin 20 so that the settling sludge in the region between the middle portion and the supernatant outflow portion is collected.

The settling sludge collected in the second hopper 22 is conveyed to the bioreactor 10 through the conveying sludge amount adjusting means 25 connected to the second hopper 22 or drawn out and discarded in a predetermined amount or a predetermined amount. Optionally carry out operations for returning and drawing off excess sludge.

FIG. 2 shows the sludge conveying means 24 and the conveying sludge amount adjusting means 25 as shown above, showing the sludge conveying line in a solid line, and shows a line drawn out and discarded by a dashed line.

The proper installation position of the hoppers of the first and second hoppers 21 takes into account the amount of sludge produced in the bioreactor 10, the speed and number of revolutions of the sludge collector, and the sludge layer formed in the sedimentation basin layer. Review of Regional Y STP] can be determined by the results.

[Review of U-Region Y STP] (See Figures 3 and 4)

Q (inflow) = 250,000 m ³ / d (12 places), 20,830 m ³

-Settling basin size (per sheet): 37m × 10m × 4.8m

Inf. BOD = 150 mg / L

First precipitation BOD removal efficiency; 30%

Bioreactor BOD presentation rate; 90%

VSS production; 0.5KS VSS / kg BOD

VSS / SS; 0.7

Conveying sludge concentration; 10,000mg / L

-Sludge profile (FIG. 3)

-SBD (х) = 1.1986х ^(-0.4292)

Where SBD (х) is the depth of the precipitated sludge

-Sludge production (1 day) = (Inf.BOD) x (ratio of VSS / SS) x (bioreactor BOD presentation rate) x (VSS production) x (per day / (ratio of VSS / SS)) x (inflow rate) × unit conversion value of sludge production) = 150 × 0.7 × 0.9 × 0.5 × (1 / 0.7) × Q × 10 ^-3

= 1,406 kg SS / d

= 140.6㎥ / d

-Speed of sludge collector: 0.3m / min (facility basis) → 432m / d

-Number of revolutions of sludge collector: total length of settling basin / speed of sludge collector = 5.2 times / day

-Sludge volume to be discarded in one revolution (minimum capacity of hopper for disposal): sludge production / number of revolutions of sludge collector (140.6 m ³ / day) / (5.2 times / day) = 26 m ³ (daily production About 20%)

Here, х is the center distance of the 1st hopper from the inflow part of a sedimentation basin as a position where a 1st hopper is installed.

As described above, the installation point of the second hopper 22 and the waste sludge drawing point of the conveying sludge amount adjusting means 25 are preferably installed at two points between the treated water inlet and the supernatant outlet. .

In addition, the conveying sludge amount adjusting means 25 is generally adjusted to convey about 1/2 of the total amount of the sludge settled in the final settling basin 20, but this is in accordance with the operating conditions of the biological reactor (10) Therefore, it cannot be determined that it is variable.

The present invention configured as described above is the sludge precipitated in the sedimentation basin is gathered into the first hopper 21 and the second hopper 22 by the sludge collector and the sludge collected in the hopper of the inflow flow rate for the activity of the biological reactor (10) The excess sludge is discarded to return around 50% and adjust the sludge residence time.

According to the present invention, by selectively disposing only sludge microorganisms which are difficult to settle in the sedimentation basin by appropriately using the sedimentation characteristics of the microorganisms above, it is possible to block the opportunity for microorganisms with poor precipitation to accumulate and proliferate in the process, thereby maintaining good overall sludge sedimentation ability. Will be. An additional effect on this is to reduce the concentration loss of the sediment supernatant from sludge collection, thereby ensuring a good discharged water quality.

The present invention provides a sludge treatment apparatus of the final sedimentation basin for improving the sludge sedimentation of the configuration as described above, the present invention is not limited to the above embodiments, the scope of the present invention without departing from the spirit of the present invention In case of supplementary construction such as facility and piping in new treatment plant, existing treatment facility, etc., it is designed to have in-line structure with one secondary sedimentation basin in existing or newly-installed treatment plant. It will be apparent to those skilled in the art that various modifications can be made at the point of drawing of the waste sludge to be applied.

Sludge treatment apparatus of the final sedimentation basin according to the present invention made as described above to control the overgrowth of filamentous bacteria to prevent efficient sedimentation operation using the selective separation function according to the settling speed of the microorganisms observed in the sedimentation basin sludge sludge poor By collecting only the microorganisms in the final settling basin and selectively discarding them, they fundamentally block the opportunity for these microorganisms to accumulate and multiply within the water treatment process.

According to the present invention as described above, the sediment with good sedimentation is selected and returned through simple physical operation in a single sedimentation basin, which not only can significantly reduce the water treatment cost, but also the aeration capacity and sedimentability during the overall water treatment process by the activated sludge method. Since only the good sludge accumulates and propagates, the aeration efficiency of the bioreactor as well as the sludge settling property of the sedimentation basin are continuously maintained and improved.

Therefore, the present invention is a very useful invention that can further enhance the technical power and economics in the water treatment field by the activated sludge method.

Claims (3)

Settling sludge of the rectangular final sedimentation basin 20 designed to have a bottom surface 23 of an incline toward the supernatant outflow from the treated water inflow portion into which the treated water flowing through the bioreactor 10 during the biological water treatment process by the activated sludge process is introduced. In the sludge treatment apparatus of the final sedimentation basin is configured to return a predetermined amount to the biological reaction tank 10 and to draw and discard the excess sludge, A first hopper 21 installed below the bottom surface 23 positioned below the treated water inlet part of the final sedimentation basin 20 to collect sedimentation sludge in the region between the treated water inlet part and the middle part; A second hopper 22 installed below the bottom surface 23 in the middle portion of the final settling basin 20 to collect the settling sludge in the region between the middle portion and the supernatant outflow portion; Sludge conveying means (24) connected to the first hopper (21) to convey the total amount of the settling sludge collected in the first hopper (21) to the biological reaction tank (10); The sludge collected in the second hopper 22 connected to the second hopper 22 may be returned to the bioreactor 10 in its entirety or may be drawn out for disposal, or a certain amount may be returned and excess sludge may be drawn out for disposal. Sludge treatment apparatus of the final sedimentation basin for improving the sludge sedimentation, characterized in that consisting of; conveying sludge amount adjusting means for selectively performing the operation (25). The method according to claim 1, wherein the installation point of the second hopper 22 and the waste sludge drawing point of the conveying sludge amount adjusting means 25 are installed at a point which is divided into two parts between the treated water inlet and the supernatant outlet. Sludge treatment apparatus of the final sedimentation basin to improve the sludge sedimentation. delete

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