KR20150003697A - Apparatus for pretreatment of waste activated sludge and waste activated sludge pretreatment process by using same - Google Patents

Abstract

The present invention relates to an apparatus for pre-treating waste activated sludge that is generated in biological treatment tanks of sewage treatment plants and wastewater treatment plants, and a method for pre-treating waste activated sludge using the same. The apparatus for pre-treating waste activated sludge that solubilizes sludge comprises: a first sludge storage tank for accommodating sludge to be treated; a high-pressure pump for introducing the sludge from the first sludge storage tank into a cavitation chamber at a pressure of 7 to 560 bars; a cavitation chamber including an orifice so that cavitation can be generated while the high-pressure sludge discharged from the high-pressure pump passes therethrough; a Venturi part including an ozone injection part for injecting ozone into the sludge discharged from the cavitation chamber; and a second sludge storage tank installed on a downstream side of the Venturi part to store the treated sludge.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste activated sludge pretreatment apparatus and a waste activated sludge pretreatment method using the activated sludge pretreatment apparatus.

The present invention relates to a pretreatment apparatus for a waste activated sludge generated in a biological treatment tank of sewage and wastewater treatment plants and a method for pretreating waste activated sludge using the same.

The waste activated sludge or excessive sludge, which is continuously generated in the biological treatment tank of the sewage and wastewater treatment plant, belongs to representative organic wastes. So far, such organic waste activated sludge has been treated by various methods such as landfill, incineration, sea exploitation, composting, auxiliary fuelization, carbonization, etc. However, most sewage and wastewater treatment plants have adopted the most favorable treatment method at cost. For this reason, large amounts of organic waste activated sludge have been dumped into the sea, sprinkled on agricultural land, or landfilled worldwide. In Korea, more than 70% of sewage sludge has been disposed of by sea dumping at the end of 2006 due to the prohibition of direct landfilling of organic waste sludge in 2003. However, by joining the London Convention, which is an international environmental treaty, such sea dumping has become totally prohibited. In the future, such organic waste sludge must be treated in a proper manner on land.

In such a background, a method for originally reducing the amount of sludge generated, a method for recycling as compost, a soil material or an auxiliary fuel, and a method for recovering an energy source such as methane (CH ₄ ) through anaerobic digestion, It is emerging as a room. In order to implement these methods, waste activated sludge must be properly pretreated, and currently developed technologies are still insufficient in terms of efficiency and cost.

In order to properly pretreat waste activated sludge, it is important to understand the structure of activated sludge floc accurately. Activated sludge flocs are linked together by extracellular polymeric substances (EPS) outside the microbial cells as microorganisms aggregate together (see Korean Patent Registration No. 10-0948494, FIG. 1).

In order to fundamentally reduce the waste activated sludge, it is necessary to break this sludge floc structure and to break the cell wall so that the microbial constituents are released to the outside. The treated sludge is then used as a carbon source in the biological treatment tank or an advanced treatment process for removing nitrogen or phosphorus, thereby making the waste activated sludge discharge amount at the sewage treatment plant zero. In order to be recycled by composting, the water content after dewatering should be lowered to less than 60%. In this case, pore water and some cell internal water around the activated sludge should be removed. The mechanical dehydration system, which is commonly used, is limited only by freedom. Therefore, alternatives are needed, and a suitable alternative method should be a technique capable of destroying these activated sludge floc structures and breaking cell walls. In the case of sludge treatment through anaerobic digestion, the higher the anaerobic digestion efficiency, the more solid matter can be converted into biogas, resulting in the recovery of a large amount of energy source, and also the reduction in the amount of sludge to be finally disposed of Effect is obtained. Therefore, a pretreatment technique that can increase the digestion efficiency is required. For this purpose, it is necessary to reduce the amount of organic substances present as solid substances and increase the amount of dissolved organic substances. This can be achieved by breaking the activated sludge floc structure and simultaneously destroying microbial cell walls and releasing intracellular material to the outside as described in the above two methods.

So far, methods such as ultrasonic treatment, high temperature heat treatment, ozone oxidation, cavitation treatment, alkali treatment, enzymatic treatment, mechanical treatment, acid treatment, microbial treatment, wet oxidation treatment and vacuum treatment have been tested and developed as pretreatment methods of waste activated sludge (Nam Kyung-cheol, quoted in the 2008 KOSEN Expert Review).

Treatment of sewage sludge with ozone oxidation destroys the cell wall of sludge reacted with ozone and releases the substance (COD component) inside the cell. In addition, polysaccharides, proteins, lipids, etc. react with ozone and are converted to low molecular weight compounds. If the ozone injection volume is high enough, the intracellular material can be converted to carbon dioxide and water and mineralized. Waste activated sludge treatment using ozone can be classified into treatment for reducing sludge and pretreatment for anaerobic digestion (Korean Patent Registration No. 10-0928972). It was reported that ozone injection of 0.05 kg O ₃ / kg TSS resulted in 19-35% sludge reduction effect in the real scale sludge reduction treatment. When this was applied to pretreatment of anaerobic digestion, 10% digestion sludge reduction effect was obtained. The ozone injection dose could be increased from 0.03 kg O ₃ / kg TSS to 0.06 kg O ₃ / kg TSS to increase the release of soluble COD material from 11% to 16%. However, it has been reported that the COD of the effluent after the anaerobic digester is increased and the cost is higher than the sludge reduction amount. In one study, the payback period for ozone pretreatment was estimated to be about 6 years. As a solution to this problem, it has been reported that the closed loop ozone oxidizing system in the mid-temperature digester after ozone pretreatment is superior to the ozone injection amount in gas production and COD reduction (Namkung Kim, 2008, KOSEN Expert Review ).

Hydrodynamic cavitation (HC) differs from ultrasound cavitation and principle but has similar characteristics in its effect. HC is produced through the turbulent flow of liquid, often occurring when there is a large pressure difference in the flow of liquid. For example, if a device is made to pass through an orifice having a small cross-sectional area while moving the fluid at a high pressure in a pipe having a certain cross-sectional area at a high speed, a large pressure difference exists in the discharge portion of the orifice, Lt; / RTI > As another example, there is an apparatus for causing the fluid passing through the orifice to meet the blade. At this time, the orifice shape is not spherical and has excellent performance when it is elliptical. In this case, the blade vibrates and cavitation can be made very distinct and effective. On the other hand, if the fluid is passed through a plurality of orifices unlike the one causing the cavitation through the orifices, the cavitation effect can be increased. Variables affecting HC include pressure, flow rate, cavitation chamber design, and time factors of cavitation. The pressure at the inlet of the orifice, the restoration pressure at the orifice discharge part, and the minimum pressure for cavitation are important, and it is necessary to clarify the related temporal factors for the commercial application (Nan Kyung Kim, 10, pp. 50-55, 2007).

One study reported that the residence time of the sludge subjected to cavitation pretreatment was significantly reduced from 13 days to 6 days, compared with the case without pretreatment at the mid-temperature anaerobic digestion. It has been reported that the treatment efficiency is remarkably improved by adding an alkali treatment prior to the cavitation treatment in the sludge reducing effect and the gas production amount (Korean Patent Publication No. 2001-0072106). This process has been commercialized in a process called MicroSludge ^TM (Canada) and has recently been applied to real-scale plants. In this process, the concentrated sludge is subjected to alkali treatment for 1 hour at pH 8.5-10 using a rotary drum concentrator, and then cavitation treatment is performed under a high pressure of 12,000 psi. As a result, sludge solubilization was possible up to 80%. At this time, the pH of the solubilized sludge changes to 6.8-7.4. It has been reported that volatile solids can be reduced to 18-78% by the mid-temperature digestion of the treated sludge. Another example of a commercialized cavitation process is the Biogest Crown Disintegration System (UK). This process utilizes very fast flow rates and performs the cavitation treatment three times before injecting the sludge into the anaerobic digester. Another example of commercialization process is Rapid Non-equilibrium Decompression (RND). In this process, CO ₂ dissolved by supersaturation under high pressure expands rapidly due to pressure drop to destroy the cell wall. The advantage of this process is that CO ₂ can be reused, the energy cost is low, and the initial investment cost is less than 2 years.

In order to increase the overall efficiency of the sewage sludge treatment, it is necessary to dispose the sludge floc structure effectively and disrupt the cell walls of the microorganisms as described above, thereby destroying the cell walls of the sludge floc, Do. Cavitation and ozone oxidation technologies provide an effective means of achieving this goal and provide superior synergies by using them together. Therefore, a process and apparatus have been introduced (WO 10-0948494) which can effectively reduce the sludge, improve the sludge dewatering efficiency, and improve the digestion efficiency by effectively integrating these technologies and pretreating the waste activated sludge. However, a sludge pretreatment process capable of further reducing the sludge weight loss, de-aeration capacity and anaerobic digestion efficiency with a simpler process is still required.

Particularly, in the conventional cavitation-ozone process, ozone was disposed in a separate contact tank, so the pump capacity for inputting ozone was large, and in treating a large amount of organic sludge, the ozone contact tank was limited in solubilizing the organic sludge uniformly have.

Korean Patent Registration No. 10-0948494 Korean Patent Registration No. 10-0928972 Korea Patent Publication No. 2001-0072106

 Journal of Korean Society of Civil Engineers, Vol. 55, No. 10, pp. 50-55, 2007.

Accordingly, it is an object of the present invention to provide a pretreatment for solubilizing sludge by combining physical treatment using cavitation and chemical treatment using ozone, in which the operation cost is lower, energy efficiency is high, and the sludge solubilization efficiency is maximized, And to provide a sludge pretreatment device having improved sludge dewatering efficiency and high anaerobic digestion efficiency.

The present invention also provides a method for pretreating sludge using the apparatus.

In order to achieve the above object, the present invention provides a pretreatment apparatus for solubilizing waste activated sludge,

A first sludge storage tank for receiving sludge to be treated;

A high pressure pump for introducing the sludge from the first sludge storage tank into the cavitation chamber at a pressure of 7 bar to 560 bar;

A cavitation chamber having an orifice through which high pressure sludge discharged from the high pressure pump passes and cavitation can be generated;

A venturi unit having an ozone injection unit for injecting ozone into the sludge discharged from the cavitation chamber; And

And a second sludge storage tank disposed downstream of the venturi unit for storing treated sludge.

According to a preferred embodiment of the present invention, the venturi portion may be constituted by connecting one to ten venturi pipes in series.

According to a preferred embodiment of the present invention, the ozone injection unit connected to the venturi pipe may be connected to the neck pipe having the smallest cross-sectional area of the venturi pipe.

According to a preferred embodiment of the present invention, the pressure of the sludge introduced into the cavitation chamber from the first sludge storage tank is more preferably 7 bar to 560 bar, and most preferably 10 bar to 420 bar.

According to a preferred embodiment of the present invention, the apparatus of the present invention may further include an ozone contact tank for ozonizing sludge discharged from the venturi portion between the downstream of the venturi portion and the second sludge storage tank.

According to a preferred embodiment of the present invention, the filtration tank may further include a filtration tank at the front end or the rear end of the first sludge storage tank for filtering out foreign substances larger than a predetermined size from the sludge to be treated.

According to another aspect of the present invention, there is provided a method for treating ozone, comprising the step of ozonating the sludge to be treated with cavitation generation by passing the sludge to be treated through a venturi tube having a high pressure cavitation chamber and an ozone injection unit A waste activated sludge pretreatment method is provided.

According to a preferred embodiment of the present invention, the waste activated sludge may be treated with alkali, hydrogen peroxide, or alkali and hydrogen peroxide prior to introduction into the venturi.

The apparatus according to the present invention solves sludge by using a high-pressure cavitation device. The sludge is maximized by providing a cavitation chamber with an orifice at the rear end of the high-pressure portion, and then the venturi portion is placed to disperse ozone. And also a good stirring effect can be obtained. Therefore, compared with the case where only the ozone mixing treatment is performed or the low pressure cavitation is performed using the venturi portion, the sludge reduction effect, the sludge dewatering efficiency improvement, and the anaerobic digestion efficiency are improved. In addition, even when the ozone contact tank is additionally used, the size of the pump and the tank can be made small.

1 is a schematic view of a waste activated sludge pretreatment apparatus according to a first embodiment of the present invention.
2 is a schematic view of a waste activated sludge pretreatment apparatus according to a second embodiment of the present invention.
3 is a schematic view of a waste activated sludge pretreatment apparatus according to a third embodiment of the present invention.
Figure 4 is a schematic diagram showing various forms of orifices.
5 is a view showing the solubilization effect of the venturi pipe.

Hereinafter, the present invention will be described more specifically by way of examples with reference to the accompanying drawings.

1 is a schematic view of a pretreatment apparatus according to a first embodiment of the present invention. The waste activated sludge pretreatment apparatus of the present invention comprises a first sludge storage tank 1, a high pressure pump (HPP) 2, a cavitation chamber 4 having an orifice 3, and an ozone injection unit 6 A venturi pipe (5) and a second sludge storage tank (7). That is, the sludge to be treated is treated by hydraulic cavitation through the high pressure cavitation unit 4 by the high pressure pump 2 from the first reservoir 1, then introduced into the venturi pipe 5 At this time, ozone is injected into the ozone injection unit 6 of the venturi pipe 5, and ozone and sludge are effectively mixed and further processed by relatively weak hydrodynamic cavitation through the venturi pipe 5.

The sludge in the high-pressure cavitation device 4 equipped with the orifice 3 is mainly divided into individual cells as the floc structure is disassembled and the bonds formed by the fibrous substances outside the cells are broken. The ozone is mixed with the sludge by the injection of ozone in the venturi portion 5, and at the same time the vaporization is weakly effected through the weak cavitation phenomenon. Ozone destroys the cell walls and extracellular tissues of the individualized cells through the oxidation reaction, Solubilization.

The pressure of the high-pressure pump 2 is preferably 7 to 560 bar, more preferably 10 to 420 bar. If the pressure is too low, the process can not proceed properly due to the loss of pressure drop in the venturi. If the pressure is excessively high, expensive equipment may be used to increase the cost. If necessary, the pump may be further used in front of the high-pressure pump 2 to smoothly operate the high-pressure pump.

In this specification, the cavitation chamber refers to a region where high-pressure cavitation is formed in the region from the orifice to the venturi front end. As shown in Fig. 4, the orifice 3 of the cavitation chamber 4 may have one or more openings and is not particularly limited. The sludge sucked into the orifice 3 by the high-pressure pump 2 is cavitated by sudden collapse of bubbles generated by passing through the expansion portion, and shock waves are generated.

The ozone injection portion 6 is formed in the neck portion of the venturi tube 5 in which the cross-sectional area of the venturi tube 5 is drastically reduced. When the fluid passes through this portion, the velocity of the fluid increases sharply, The pressure of the gas is greatly reduced. In other words, ozone is sucked naturally because of the negative pressure, so there is no need to operate a separate pump for ozone injection. In addition, the gas in the dissolved state in the fluid is separated from the fluid, or a phase change of water occurs, and cavities are formed to generate a cavitation phenomenon.

This hydraulic cavitation phenomenon has been used in other technical fields. However, ozone injection using a high-pressure cavitation device and a venturi pipe can be used to completely eliminate the need for an ozone contact tank or to greatly reduce the size thereof, Gas-liquid mixing can be achieved. This can significantly improve energy efficiency and reduce costs.

In the pretreatment apparatus of the present invention, as shown in FIG. 1, only one venturi pipe 5 having an ozone injection unit 6 is connected in series. However, two or more venturi pipes 5 may be connected in series to form a venturi unit. In this case, the solubilization efficiency can be further improved by passing the sludge through each venturi pipe. In particular, each of the venturi pipes may be detachably connected so as to easily adjust the number of the venturi pipes as needed. Also, ozone can be injected into each venturi tube, but in some cases, it can be injected only into a part.

2 is another embodiment of the present invention. In addition to the first sludge storage tank 1, the high-pressure pump 2, the cavitation chamber 4 having the orifice 3, the venturi unit 5 including the venturi pipe and the second sludge storage tank 7, , And a filtration tank (10) for filtering the sludge to be treated when the sludge contains a large amount of solid matter. 2 shows a case where the filtration tank 10 is installed at the front end of the first sludge storage tank 1, but it may be installed at the rear end. Further, although not shown, it may be equipped with a means for adding a drug for promoting the solubilization of the sludge, that is, before introduction into the alkali or hydrogen peroxide isothermal venturi portion 5.

In another embodiment, as shown in FIG. 2, the ozone contact tank 20 for further ozonizing the sludge discharged from the venturi unit may be provided. In the case where the ozonized contact tank 20 is provided The size of the reactor or the pump capacity may be much smaller than when the apparatus according to the present invention is not used, so that the facility can be made compact.

There are two methods of contacting the sludge and ozone in the ozone contact tank 20. One is a gas-liquid mixing pump, and the other is an injector / venturi. In the former case, the sludge in the contact tank 20 is taken out by the gas-liquid mixing pump 30, the sludge is mixed with the ozone through the gas-liquid mixing pump 30 while the ozone is injected therein, (See FIG. 2). In the latter, the sludge of the ozone contact tank 20 is taken out by using the liquid transfer pump 40, and the ozone is injected into the neck portion while the sludge passes through the injector / And then introduced into the ozone contact tank 20 (refer to FIG. 3). Any method can be used effectively. Hereinafter, embodiments of the present invention will be described in detail. It should be understood, however, that such description is not to be construed as limiting the scope of the invention, and that variations may be readily made by those skilled in the art, as set forth in the description and claims of the invention, Belongs.

Example 1

Sewage sludge samples were taken from a biofilm reactor (MBR) pilot facility (treatment capacity: 300 tons / day, average TSS: 10,000 mg / L) installed at a sewage treatment plant. An apparatus (a series connection of a venturi tube) as shown in Fig. 1 was used, and specific specifications are as follows.

First sludge storage tank capacity: 1.5 m ³

High pressure pump flow rate: 17L / min

High pressure pump pressure: 150 bar

Sectional area of orifice: 0.785 mm ²

Venturi tube cross section: 7.065mm ²

Ozone dose: 120mg / L

Filtration specifications: Stainless steel screen with 1.0 mm mesh (screen area: 0.196 m ² )

Ozone Contact Pump and Pump Specifications: 1.2 m ³ size cylindrical contact tank equipped with foam breaker at the top, 2HP 380V gas-liquid mixing pump (Shinpung acid acid pump)

The ozone generating apparatus is a water-cooled apparatus (SW-50, SeungWoo Seitech Co., Ltd.), and the ozone generating capacity is at most 50 g-O ₃ / hr. Oxygen (99.99%) stored in the high pressure vessel was used as raw material oxygen.

The treated sludge was analyzed by the following method.

① pH - Each sample was measured for pH using a pH meter.

Temperature - The temperature of each sample was measured using a thermometer.

③ suspended solids (SS) - glass fiber filter cloth (GF / C) was washed with purified water in advance and placed on a watch tray, dried in a dryer at 105-110 ° C for 2 hours, placed in a sulfuric acid desiccator, The weight was precisely weighed and attached to the filter. The sample was filtered by suction while injecting the appropriate amount into the filter, and then the filter was washed with water for several times. The filter paper was taken out from the filter while taking care of the fineness, and dried in a dryer at 105-110 ° C for 2 hours The mixture was cooled in a desiccator of sulfuric acid and allowed to cool. The difference in the glass fiber clearance weight before and after filtration was calculated to be the amount of suspended material.

④ SCODcr - The sample was filtered with glass fiber filter paper (GF / C), 2 mL of the filtered solution was injected into the water CODcr assay kit, and reacted at 150 ℃. SCODcr was analyzed using HS-2300Plus water quality analyzer (Humas, Korea) Respectively.

Comparative Example 1 - When only high pressure cavitation was performed

In the case of performing only high-pressure cavitation (200 bar) without ozone treatment, the experimental example described in Korean Patent Registration No. 10-0948494 can be referred to. The results are as follows.

Comparative Example 2 - Ozone treatment with an ozone contact pump without using a venturi tube

An experimental result in the case where only ozone is treated by the ozone contact pump without high-pressure cavitation can also be referred to Korean Patent Registration No. 10-0948494. Experimental results according to ozone input are as follows.

(2-1) Ozone input amount 30 g / hr

(2-2) Ozone input amount 50 g / hr

Increasing the amount of ozone increased from 30 g / hr to 50 g / hr resulted in an increase in SCOD and an increase in SCOD / SS.

Comparative Example 3 Cavitation and ozone treatment without using a venturi tube

Experimental results in case of ozone treatment by cavitation and ozone contact pump can also be found in Korean Patent Registration No. 10-0948494. Experimental results according to ozone input are as follows.

(3-1) Ozone input amount 30 g / hr

(3-2) Ozone input amount 50 g / hr

Comparison of treatment performance according to unit ozone input

When the apparatuses of Example 1 and Comparative Examples 2 and 3 in which ozone was introduced were used, the rate of increase of SCODcr per unit ozone input amount was as follows.

division Ozone input concentration Increase in SCODcr Increase rate of SCODcr per unit ozone input Remarks
(Throughput, ozone generation, ozone injection time) Example 1 120 mg / L 1200mg / L 10 1 m ³ , 50 g / hr, 2.4 hr Comparative Example 2 One 250mg / L 520mg / L 2.08 20 L, 30 g / hr, 10 min 2 417 mg / L 870 mg / L 2.09 20 L, 50 g / hr, 10 min Comparative Example 3 One 250mg / L 1,028 mg / L 4.11 20 L, 30 g / hr, 10 min 2 417 mg / L 1,204 mg / L 2.89 20 L, 50 g / hr, 10 min

It can be seen from Table 6 that compared with the case where the ozone contact pump is used (Comparative Example 2) or the case where the ozone contact pump is used (Comparative Example 3) without using a venturi tube, It can be seen that when the venturi tube is used after cavitation, the SCODcr increase, that is, the solubilization effect of the sludge, can be obtained much better than the same ozone input amount.

Comparative Example 4 - Low pressure cavitation using a venturi tube only

FIG. 3 of the Korean Patent Registration No. 10-0866620 of Samchang Corporation graphically shows the influence of the number of the venturi pipes on the sludge solubilization efficiency (see FIG. 5).

5, SCOD values of 1,600 mg / L were obtained after 20 hours of treatment with one venturi tube. On the other hand, when two venturi tubes were connected in series, the SCOD reached to 2,700 ㎎ / L after 14 hours treatment at the start of operation, and thereafter, the increase of SCOD was insignificant. The increase of the SCOD after 20 hours treatment was about twice that of the venturi tube when two venturi tubes were connected in series. This shows that the cavitation generation area is doubled by connecting two venturi tubes in series.

Compared with the present invention, Comparative Example 4 shows very slow processing performance. In Comparative Example 4, SCOD value of 1,600 mg / L was required to be treated for 20 hours with a single venturi tube. In contrast, in the present invention, the SCOD value reaches 1,550 mg / L through two stages of low-pressure cavitation after high-pressure cavitation, and the treatment time is within one minute to three minutes. This shortening of time shortens the space and area for the treatment facility and enables the implementation of the compact facility, resulting in the reduction of the facility investment cost and the operation management cost.

Comparative Example 5 - PFR reactor after ozone injection

US Patent 7,695,622 (April 13, 2010) by Praxair Technology, Inc., presents a technique that can reduce the amount of ozone injected in treating sludge with ozone for sludge reduction compared to other prior art documents. In this way, ozone is injected at a single or multiple injection points and is then processed in conjunction with a plug flow reactor. However, direct comparison is difficult because SCOD value indicating the degree of solubilization of sludge is not presented.

However, in the present invention in which ozone treatment is performed through cavitation, ozone is injected at about 100 mg / L to 150 mg / L. When the sludge with TSS of 10,000 mg / L was placed in the continuous mixing reactor (CSTR) and the ozonation was carried out using one venturi tube, the SCOD increase rate increased from 400 mg / L to 1200 mg / L at the ozone injection rate of 120 mg / And increased to 1600 mg / L when cavitation was included. In the case of the present invention, the sludge reduction rate is 40% under this condition, which is 0.025 kg O ₃ consumed / kg sludge reduced compared with the 0.05 kg O ₃ consumed / kg sludge reduced shown in Comparative Example 5, . As a result, it can be seen that the present invention has about twice the effect of sludge reduction on the same ozone input.

As has been described in the above examples and comparative examples, in the case of Comparative Example 1 and Comparative Example 4 in which only cavitation was performed without ozone treatment, the sludge solubilization ratio was significantly lower than in the case of ozone treatment. Also, when the ozone contact pump is used without using a venturi pipe as in the case of Comparative Example 2 and Comparative Example 5, or when a PFR reactor is used after ozone injection through a venturi pipe, the throughput is lower than in the case of the present invention. In addition, when the venturi tube is used after the high-pressure cavitation as in the present invention, the SCODcr increase, that is, the sludge solubilization effect, which is much better than the same ozone injection amount, can be obtained as compared with the case where the general ozone contact pump is used without using the venturi tube after high pressure cavitation.

1 First sludge storage tank
2 High pressure pump (HPP)
3 orifice
4 Cavitation chambers
5 Venturi Department
6 ozone injection part
7 Second sludge storage tank
10 filtration tank
20 Ozone contact tank
30 gas-liquid mixing pump
40 liquid transfer pump
50 Injector / Venturi

Claims (6)

A pretreatment apparatus for solubilizing waste activated sludge, comprising:
A first sludge storage tank for receiving waste activated sludge to be treated;
A high pressure pump for introducing the sludge from the first sludge storage tank into the cavitation chamber at a pressure of 7 bar to 560 bar;
A cavitation chamber having an orifice through which high pressure sludge discharged from the high pressure pump passes and cavitation can be generated;
A venturi unit having an ozone injection unit for injecting ozone into the sludge discharged from the cavitation chamber;
A second sludge storage tank disposed downstream of the venturi unit to store treated sludge; And
Between the downstream of the venturi and the second sludge reservoir. And an ozone contact tank for ozone treatment of the sludge discharged from the venturi portion. The ozone contact tank is provided with a venturi injector for drawing a part of the sludge of the ozone contact tank to inject ozone into the ozone contact tank again. The waste activated sludge pretreatment apparatus comprising:
The method according to claim 1,
Wherein the venturi part is constituted by connecting one to ten venturi pipes in series.
The method according to claim 1,
Wherein the ozone injection unit connected to the venturi pipe is connected to a neck having a narrowest cross-sectional area of the venturi pipe.
The method according to claim 1,
Further comprising a filtration tank at a front end or a rear end of the first sludge storage tank for filtering out foreign substances having a predetermined size or more from the sludge to be treated.
A method for pretreating a waste activated sludge using the apparatus of any one of claims 1 to 4.
6. The method of claim 5,
Characterized in that the waste activated sludge is treated with alkali, hydrogen peroxide, or alkali and hydrogen peroxide prior to introduction into the venturi.

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