KR101266482B1 - Activated sludge disintegration apparatus using microbubble and ultrasonification - Google Patents

Abstract

The present invention relates to a sludge reduction apparatus using micro-bubbles and ultrasonic waves, the sludge reduction apparatus using micro-bubbles and ultrasonic waves according to an embodiment of the present invention, as a basic configuration, micro-bubble contact tank, ultrasonic contact tank, circulation piping, suction means, It consists of a pressurized circulation pump, preferably adds an anaerobic digestion tank, and when there is no anaerobic digestion tank in the existing sludge treatment facility, it comprises a structure that simultaneously uses a microbubble contact tank as an aerobic digestion tank. According to the present invention, the microbubbles generated by the microbubble generating device and the pressurized circulation pump solubilizes the sludge by using hydrodynamic force, thereby reducing the required sludge solubilization energy by the ultrasonic wave and generating synergistic action, thereby making the existing sludge pretreatment method possible. The sludge can be effectively reduced by minimizing energy consumption.

Description

Activated sludge disintegration apparatus using microbubble and ultrasonification}

The present invention relates to a sludge reduction device using micro-bubbles and ultrasonic waves, and more particularly, to reduce the cost of sludge economically by reducing the cost of energy significantly compared to conventional ultrasonic treatment alone through the sludge pretreatment using micro-bubbles and ultrasonic generators. It relates to a sludge reduction device that can be.

As regulations on sewage sludge disposal are tightened, research and technology development on sludge reduction technologies are being actively conducted. The microorganisms that constitute sewage and wastewater sludge are low in biodegradability because they are surrounded by solid cell walls, have high content of bound water such as intracellular water and gap water, and high hydrophilicity. Separation not available.

Considering the characteristics of the sludge, the sludge pretreatment process is necessarily added to the front end of the sewage and wastewater sludge treatment system. That is, the purpose of the sludge pretreatment is to increase the biodegradability of the sludge by destroying the cell wall to promote hydrolysis of the cell components. The present invention relates to this sludge pretreatment method.

Major sludge pretreatment methods studied to date include ozone treatment, ultrasonic treatment, alkali treatment, heat treatment, enzyme treatment, acid treatment, mechanical grinding, chlorine treatment, single treatment such as alkali / ultrasound combination treatment, and alkali heat treatment treatment. .

Of these methods, physical treatment techniques such as ultrasonic waves have the advantage of not generating harmful substances to the environment during the treatment process. Sludge pretreatment by ultrasonic wave is the principle of sludge pretreatment using cavitation, and instantaneous high temperature and high pressure condition is formed by the destruction of cavitation cavity and bubble generated inside the liquid by cavitation, and by the shock wave and shear force It is a technology that uses the destruction of surrounding sludge. That is, when irradiating ultrasonic waves with a high acoustic intensity, when the energy input by ultrasonic waves exceeds the binding energy of water molecules, cavitation occurs due to the partial pressure drop.

This technique has the advantage of high sludge treatment efficiency and relatively little influence of solids content or viscosity, but has the disadvantage of high energy input and relatively high facility maintenance cost.

Recently, as a pretreatment method for reducing sludge, hybrid processes are being actively developed that combine two or more processes such as ozone + physical crushing and ultrasonic + alkali treatment, rather than conventional single methods such as ozone or ultrasonic wave and physical crushing. As a hybrid pretreatment method for reducing existing sludge, Application Nos. 10-2007-0073678, 10-2008-0041276, etc., propose a sludge reduction method using alkali decomposition, an ultrasonic process, an ozone dissolving device, and microbubble ozone.

In particular, the mechanical pretreatment method that breaks down a large mass of sludge by hydrodynamic method using existing physical devices to cause decomposition is well carried out by microorganisms in which the gaseous components dissolved in the sewage are released and bubbles are formed. When the large mass of sludge is crushed and divided into small pieces, the specific surface area of the crushed sludge, which is the food (substrate) of the digestive microorganism, increases, thereby facilitating the decomposition of the sludge.

Therefore, when combined with the ultrasonic treatment method, which is a conventional sludge reduction method, there is an advantage that the sludge can be treated more economically than a single method.

In the present invention, although the sludge pretreatment method using ultrasonic waves for the reduction of sludge has been proved to be effective in reducing the site, it is a new hybrid process using micro-bubbles and ultrasonic combination treatment using physical impact as a new hybrid process to overcome the difficulty of applying the site with high facility cost and maintenance cost. Thus, to increase the sludge reduction efficiency than the ultrasonic alone, it is to provide an economical treatment device that reduces the facility cost and operating cost.

According to an aspect of the present invention,

Microbubble contact tank for processing the introduced sludge by using the hydrodynamic force of the microbubble; And an ultrasonic contact tank connected to the microbubble contact tank for solubilizing sludge using ultrasonic cavitation,

The microbubble contact tank,

A circulation pipe connected to allow the sludge discharged from the microbubble contact tank to be circulated again;

A suction means disposed on a path of the circulation pipe and configured to suck air; And

Connected to the suction means, the pressure circulation to crush the sludge contained by the hydrodynamic force generated by the sequential decompression and pressurization while generating micro bubbles by sequentially applying pressure and pressure to the sucked air Including a pump,

The ultrasonic contact tank,

A sludge reduction apparatus using microbubbles and ultrasonic waves is connected to an ultrasonic wave generator so as to solubilize the sludge firstly in a microbubble contact tank again using the cavitation effect of ultrasonic waves.

In the sludge reduction apparatus using microbubbles and ultrasonic waves according to the present invention, the microbubble contact tank and the ultrasonic contact bath are connected to the circulation pipe so that the conveyance can be carried out, and thus, the energy cost can be effectively reduced to 66% level compared to the ultrasonic single sludge pretreatment.

In the sludge reduction apparatus using micro-bubbles and ultrasonic waves according to the present invention, the micro-bubble contact tank and the ultrasonic contact tank is connected to the rear end anaerobic digestion tank is capable of reducing sludge through biological treatment by the anaerobic microorganism solubilized sludge. In the case of a sludge treatment facility having no anaerobic digester, the microbubble contact tank can be used as an aerobic digester capable of reducing sludge by aerobic microorganisms.

In the sludge reduction apparatus using micro-bubbles and ultrasonic waves according to the present invention, the appropriate ultrasonic injection energy in the ultrasonic contact device is 10,000kJ / kg-TSS ~ 30,000kJ / kg-TSS as an appropriate input energy range.

According to the present invention, a microbubble contact tank capable of pretreatment of sludge by physical fracturing by microbubbles generated by the microbubble generating device and physical crushing by a pressurized circulation pump and a cavitation effect of ultrasonic waves are used for dismantling the sludge cell wall. It is composed of ultrasonic contact tanks, which reduces energy cost and reduces facility cost for pretreatment compared to conventional sludge pretreatment, which is the most serious problem of sludge pretreatment, which can economically reduce sludge, which can drastically reduce operating and facility costs. Do.

1 is a schematic view showing the configuration of a sludge reduction apparatus using micro-bubbles and ultrasonic waves according to an embodiment of the present invention.
2 is a view schematically showing a micro-bubble generating device according to the present invention.
3A and 3B are graphs showing changes in TSS and particle size according to contact time in the microbubble contact bath, respectively.
Figure 4a is a graph showing the behavior of the CODcr solubilization rate according to the input energy in the micro-bubble and ultrasonic treatment apparatus and ultrasonic treatment unit according to the present invention.
Figure 4b is a graph showing the behavior of the loss ratio of the TSS according to the input energy in the micro-bubble and ultrasonic treatment apparatus and ultrasonic treatment unit according to the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a schematic view showing the configuration of a sludge reduction apparatus using microbubbles and ultrasonic waves according to an embodiment of the present invention.

As shown in FIG. 1, the sludge reduction apparatus using microbubbles and ultrasonic waves according to an embodiment of the present invention has a microbubble contact tank 10, an ultrasonic contact tank 20, a circulation pipe 23, and suction as a basic configuration. Means 24, pressurized circulation pump 25, the ultrasonic generator 26 is made, including the anaerobic digester 30 is added to the rear end.

In the present invention, the microbubble generating device comprising a suction means 24 and a pressurized circulation pump 25 in the microbubble contact tank 10 for sludge pretreatment in front of the anaerobic digestion tank 30 that can reduce the sludge biologically In addition, by adding an ultrasonic generator 26 and the ultrasonic contact tank 20 in order to contact the ultrasonic waves to the sludge, to increase the solubilization rate through the sludge pretreatment to reduce the sludge of the anaerobic reaction tank 30 ( A sludge reduction device using microbubbles and ultrasonic waves, which can increase the amount of dyeing, was completed.

That is, the present invention, by using the hydrodynamic force of the micro-bubbles generated through the micro-bubble generating device (24, 25) in the microbubble contact tank 10 in order to reduce the sludge effectively, the sludge is partially ultrasonicated again Sludge cell wall is destroyed by using ultrasonic waves generated by the ultrasonic generator 26 in the contact tank 20 to promote solubilization of the sludge so that the sludge cell wall is destroyed in the anaerobic digestion tank 30 in the rear stage and the substrate sludge is destroyed. Biodegradation by anaerobic or aerobic microorganisms promotes final sludge reduction.

Hereinafter, each structure of the sludge reduction apparatus by this invention is demonstrated.

The microbubble contact tank 10 plays a role of promoting the reduction of sludge by the cavitation effect of the microbubbles generated in the microbubble generator and the physical grinding action of the pressurized circulation pump.

2 is a view schematically showing a microbubble generating device according to the present invention.

2, the micro-bubble generating device circulation pipe 23, a pressure circulation pump 25, the injector as the suction means 24, by-pass (By-pass), pipe (27), inlet and outlet level probe It comprises a ( 23c, 23d) . The injector as the suction means 24 provided in front of the pressure circulation pump 25 has a diameter smaller than that of the circulation pipe 23 so that air flows in a self- suction manner in front of the pressure circulation pump 25 . , this enables the incoming air to pass through the rotational difference of the pressure circulation pump 25, which passes through the reduced pressure, and the impeller at the impeller front end and dissolved by the high pressure generated for a short period, through the impeller saturated When the liquid enters the pressure exhalation tank , the pressure is released and the air dissolved according to Henry's law is again generated as microbubbles.

The microbubbles generated therefrom have a size of about 10 to 100, and the required flow rate and air amount are controlled by the opening degree of the bypass valve 27a.

When such microbubbles are generated, it is possible to accelerate the sludge solubilization by applying a physical force to the sludge cell wall by a hydrodynamic force similar to the microbubble formation by cavitation generated by ultrasonic waves. Since the physical crushing effect of the sludge due to the rotation difference of the circulation pump 25 can also be expected, the energy required for the ultrasonic generator can be reduced by performing a part of solubilization of the sludge by ultrasonic waves.

The ultrasonic contact tank 20 is configured by connecting the ultrasonic generator 26 to the contact reaction tank. Ultrasound can be heard by humans Ultrasound is a sound with a frequency of 20kHz to 10MHz beyond the range of human hearing. Ultrasonic energy above a certain intensity produces tiny bubbles. This action is the cavitation phenomenon.

These cavitation bubbles generate and collapse within tens of microseconds and generate powerful hydrodynamic shear forces. Cavitation bubble generation occurs faster at frequencies of 20-40 kHz. When the ultrasonic wave is irradiated on the sludge, the ultrasonic wave generates a compression force and an expansion force periodically. Inflation forces occur where the negative pressure is applied to a solution or suspension. Due to the applied negative pressure, the gas dissolved in the solution is vaporized and cavitation bubbles, that is, micro bubbles are generated.

The compressive force is also applied periodically, and due to the periodic action of the compressive and expansion forces, the microbubbles are large in size just before they explode violently. Eventually, the action by cavitation is the result of a process in which microbubbles are formed and their size increases and rapidly collapses. Indeed, the bursting of hollow bubbles separates bacteria from the microbial community and makes the cell walls more brittle. This makes it easier for toxic substances to penetrate into cells and lowers the activity of bacteria.

Ultrasonic energy can be applied as a pretreatment to break down sludge flocs and destroy cell walls of microorganisms to improve hydrolysis during digestion. Destruction of the cell wall causes organic material in the cells to flow out of the sludge mixture. However, sludge pretreatment using ultrasonic waves has been a major deterrent to the spread of the high cost of ultrasonic energy input into sludge reduction facilities at home and abroad.

Therefore, the present invention is designed to enable a low-cost, high-efficiency sludge reduction device by reducing the energy cost due to the ultrasonic wave by using a microbubble contact tank in which the sludge is circulated at the front end and circulating the sludge as needed.

The rear end of the ultrasonic contact tank 20 was installed an anaerobic tank 30, which is a sludge reduction facility using microorganisms for practical application. Through the microbubble contact tank 10 and the ultrasonic contact tank 20, the cell wall is destroyed and solubilized sludge can be biodegraded using the most economical anaerobic microorganisms to reduce the original inflow sludge by 30-50%. Done.

Anaerobic treatment of the solubilized sludge introduced solubilizes the sludge so that it is enclosed in the cell wall, making it easier to biologically treat sludge that is difficult to degrade, thereby facilitating the hydrolysis that is primarily performed in anaerobic digestion. It makes the sludge process easier. Anaerobic microorganisms that cause this action include, for example, acid-producing bacteria, methane bacteria, denitrification bacteria, and hydrogen bacteria. Known anaerobic microorganisms can be used.

In addition, sludge pretreatment facilities (ultrasound, ozone, alkali treatment, etc.) are generally installed at the front of the anaerobic tank that can remove the sludge biologically, but if the anaerobic tank is not installed in the existing sludge treatment facility, microbubble contact tank (10) It can be selectively used as an aerobic digester. Since the microbubble contact tank 10 is supplied with oxygen by the microbubble generator, the aerobic microorganism serves as an aerobic digester in which aerobic microorganisms are easily inhabited, thereby allowing sludge to be reduced while circulating the microbubble contacting tank and the ultrasonic contacting tank. .

The invention of the sludge reduction apparatus using the micro-bubble and the ultrasonic wave is used only in the sludge pretreatment device when the anaerobic digestion tank is installed according to various needs, and in the ultrasonic contact tank 20 when the anaerobic digestion tank 30 is not installed. The sludge is circulated back to the micro-bubble contact tank 10 and the residence time is increased to enable decomposition by the microorganisms of the sludge, and thus, the role of an aerobic digestion tank is possible.

In order for the microbubble contact tank 10 configured as described above to serve as an aerobic digester, supply of oxygen capable of activating the decomposition of aerobic microorganisms is essential. Since the microbubble generating device supplies oxygen together with the microbubble generation as described above, a separate oxygen supply device, such as a blower and a diffuser, is unnecessary, thereby enabling the construction of an economical sludge reduction device.

Hereinafter, the present invention will be described with reference to Examples of the present invention.

Microbubbles In contact bath Sludge  Treatment efficiency experiment

In order to examine the effect of sludge by the microbubble device, the sludge treatment characteristics according to the residence time (HRT) in the microbubble contact tank 10 were examined. The microbubble contact tank was used as a 300F x 700mm cylindrical reactor and the microbubble generator was operated based on the circulation rate 10L / min using a pressurized circulation pump of 220V and 255W capacity. The change in total solids (TSS) and particle size were measured by increasing the contact time of the microbubble bath from 1 to 30 minutes. The MLSS concentration of the sludge to be treated was 10,000mg / L, and the changes in the microbubble contact tanks were examined through time-sampling.

As a result of grasping the physical change of the sludge while changing the residence time in the microbubble contact tank, as shown in Figure 3a, the TSS reduction rate was increased to 6.2% by 30 minutes of contact time. In addition, as shown in FIG. 3b, the size of the sludge floc was measured to indicate that the initial average size decreased from 25 μm to 20 μm after 30 minutes of contact.

Example : Micro bubbles and ultrasonic waves according to the present invention Sludge  With weight loss device Sludge  Treatment (Comparative Experiment with Ultrasonic Wave Treatment)

The reactor size was 300F x 700mm for the pressure aerobic reactor and 500F x 500mm for the ultrasonic anaerobic reactor and the circulation volume of the pressurized circulation pump was operated at 10L / min. The ultrasonic generator was tested with an output of 120W using an ultrasonic generator with a frequency of 25 kHz and a maximum power of 400W. The ultrasonic contact bath measured the degree of sludge solubilization while varying the total ultrasonic injection energy while increasing the contact time to 1L.

The sludge used in the experiment was a sewage treatment plant surplus sludge. The concentrations were TCODcr 9,720mg / L, SCODcr 30mg / L, TSS 10,750mg / L, VSS 7,200mg / L. In addition, the contact time of the microbubble contact bath was 30 minutes, which was optimally shown in the basic test results. The contact time of the ultrasonic contact bath was experimentally changed from 0 to 20 minutes in order to compare the solubility of sludge per input energy. In this experiment, we compared the improvement of sludge treatment performance on the basis of solubilization rate by comparing the microbubble + ultrasonic combination treatment with the ultrasonic single treatment under the same conditions.

Sludge  Reduction Evaluation

Ultrasonic Monotherapy and Microbubble + Ultrasonic Combination Treatment Sludge Solubilization  evaluation

The degree of sludge treatment according to the injection energy according to the combination of microbubble and ultrasonic wave was examined through the solubilization rate and the reduction rate using the change of TSS and SCODcr.

-TSS reduction rate formula (%): Percentage of decrease in TSS due to sludge pretreatment (%)

[Formula 1]

-SCODcr solubility rate formula (%): percentage of SCODcr amount generated for TCODcr following sludge pretreatment.

[Formula 2]

Ultrasonic injection energy unit, Specific Energy (kJ / kg-TSS): Input energy per unit solids volume (TSS x Volume)

[Equation 3]

As shown in FIG. 4A, the ultrasonic single treatment consumes about 30-40% more energy than the microbubble + ultrasonic combined treatment in order to obtain the same sludge solubilization rate as a result of the ultrasonic single treatment and the microbubble + ultrasonic combination treatment experiment according to the input energy. It can be seen that the ultrasonic alone treatment is Specific Energy 28,000kJ / kg-TSS, and the microbubble + ultrasonic combination treatment requires Specific Energy 18,000kJ / kg-TSS to obtain 10% solubilization rate.

At this time, as shown in Fig. 4b, the reduction ratio by the sludge pretreatment also showed that the sludge TSS reduction ratio was 6.4% in the ultrasonic alone treatment when the specific energy 18,000kJ / kg-TSS was added. I could get the harmonics.

The empirical results show that the solubilization and reduction of the sludge through the pre-treatment of microbubble + ultrasonic wave is less energy cost and the pretreatment effect is superior to the ultrasonic pretreatment alone.

Comparison of input energy efficiency of processing equipment

Table 1 below shows the results of comparing the input energy of the sludge reduction apparatus using the micro-bubbles and ultrasonic waves of the present invention based on the experimental results (FIGS. 4A, 4B) obtained through the examples.

division Criteria for achieving 10% solubilization rate Remarks kJ / kg-TSS kcal / kg-TSS Ultrasound Input Energy 28,000 6,720 100% Micro Bubble + Ultrasonic Wave
Combination Processing Ultrasonic Input Energy 18,000 4,320 Micro bubble input energy  675 162 system 18,675 4,482 66.6%

As shown in Table 1 and FIG. 4A, when the input energy was calculated based on the solubilization rate target of 10%, the input energy of the ultrasonic treatment alone was 28,000 kJ / kg-TSS (6,720 kcal / kg-TSS). The input energy of the ultrasonic combination treatment is 18,675kJ / kg-TSS (4,482kcal / kg-TSS), and it can be seen that the energy consumption is small at 66.6% of the input energy during the ultrasonic treatment alone.

In the above, the embodiment of the present invention has been described in detail. However, the scope of the present invention is not limited to the above embodiments, but includes a range that can be easily converted or deleted within the scope of the appended claims, and without departing from the gist of the present invention as claimed in the claims. Anyone skilled in the art is deemed to fall within the scope of the claims described in the present invention to the extent possible to vary.

10: microbubble contact bath 20: ultrasonic contact bath
21: pressure exhalation reactor 23: circulation piping
24: suction means 25: pressurized circulation pump
26: ultrasonic generator 30: anaerobic digester

Claims (4)

Microbubble contact tank for processing the introduced sludge by using the hydrodynamic force of the microbubble; And an ultrasonic contact tank connected to the microbubble contact tank for solubilizing sludge using ultrasonic cavitation,
The microbubble contact tank,
A circulation pipe connected to allow the sludge discharged from the microbubble contact tank to be circulated again;
A suction means disposed on a path of the circulation pipe and configured to suck air; And
Connected to the suction means, the pressure circulation to crush the sludge contained by the hydrodynamic force generated by the sequential decompression and pressurization while generating micro bubbles by sequentially applying pressure and pressure to the sucked air Including a pump,
The ultrasonic contact tank,
It is connected to the ultrasonic generator and solubilizes the sludge firstly pretreated in the microbubble contact tank again using the cavitation effect of the ultrasonic waves.
The microbubble contacting tank and the ultrasonic contacting tank are connected to the rear anaerobic digestion tank to reduce sludge through biological treatment by anaerobic microorganisms, solubilizing the sludge solubilized through pretreatment. Sludge reduction apparatus using micro-bubbles and ultrasonic waves, characterized in that the contact tank can be used as an aerobic digestion tank capable of reducing sludge by aerobic microorganisms. The method of claim 1,
Sludge reduction apparatus using micro-bubbles and ultrasonic waves, characterized in that the micro-bubble contact tank and the ultrasonic contact tank is connected to the circulating pipe so that the transport can be carried out to effectively reduce the energy cost to 66% than the conventional ultrasonic single sludge pretreatment. delete 3. The method according to claim 1 or 2,
Sludge reduction apparatus using micro-bubbles and ultrasonic waves, characterized in that the appropriate ultrasonic injection energy in the ultrasonic contact device is 10,000kJ / kg-TSS ~ 30,000kJ / kg-TSS in the appropriate input energy range.

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