KR102005213B1 - Sludge treatment method before dehydration - Google Patents

Abstract

The present invention relates to a pre-dewatering sludge treatment method for pre-treating wastewater sludge to increase pressure dewatering efficiency before pressurized dewatering treatment for wastewater sludge, wherein the pre-dewatering sludge treatment method comprises: A method for pretreating sludge, comprising the steps of: (a) transferring stored, sludge from a sludge reservoir to a pressurized dewatering facility via at least one of a settling, biological reaction, concentration, and digestion process for the wastewater; (b) first injecting an inorganic coagulant to provide a cation before injecting the foaming oxidant into the path for transfer to the pressurizing and dewatering facility; And (c) injecting a foaming oxidizing agent, wherein the cell wall or cell membrane of the microorganism in the sludge is weakened or destroyed by the foaming oxidizing agent, and in the sludge squeezing process by the pressurizing and dewatering facility, The cell wall or cell membrane expands and breaks in the direction of bubbles generated by the foaming oxidizing agent and the bubbles are discharged to the outside of the sludge in the pressing process to form a drainage passage, And the water content is lowered to 60% or less.

Description

[0001] Sludge treatment method before dehydration [

The present invention relates to a method for pre-treating wastewater sludge in order to increase pressure dewatering efficiency before pressurized dewatering treatment for wastewater sludge.

It has become an urgent task to reduce the water content of wastewater sludge in order to fuel or compost the wastewater sludge, because the marine dumping of wastewater sludge is prohibited and land reclamation becomes difficult due to the rejection of the disgusting facilities in each province. In recent years, wastewater sludge has been discharged at a water content of 63 ~ 66% through a filter press, but it has not yet reached the level of self-combustion, so it is necessary to lower the water content further.

Various methods for lowering the water content of the wastewater sludge have been proposed in the past, and some examples are as follows. Open No. 10-2015-0053993, entitled "Dewatering Method and Dewatering Apparatus for Sludge", discloses a method of directly heating sludge by heated water vapor or hot air at the sludge inlet side and dehydrating the sludge in a heated state in a screw press , There is a problem of having to cope with a lot of energy costs in order to obtain a sufficient effect.

In the method of re-dewatering the water content in the sludge cake to 40% level by mechanical mixing and compression in the presence of additives, the first dehydrated sludge cake is coated with 1 ~ 3 mm sized cellulose powder such as wood flour, At least one excipient powder selected from the group consisting of powder, palm powder, arsomel powder, cornstarch powder and corn powder is added to the mixture, and the mixture is rapidly rotated within a period of 1 to 2 minutes at a rotation speed of 150 to 200 rpm with a stirrer to obtain a sludge moisture content of 60 3% , The sludge cake having a water content of 40 ± 3% was obtained by rehydration within 12 minutes while repeating compression and stopping at 50 to 200 kg / cm 2 with a filter press compactor, and the sludge cake was put into a mixer at 150 to 200 rpm And crushing and pulverizing the mixture for 2 to 3 minutes, and then selecting and collecting the excipient only by a vibration screen having a diameter of 1 to 3 mm. However, in this case, it is necessary to construct a facility for applying a high pressure of 50 to 200 kg / cm 2 in view of the fact that the equipment for recovering the excipient and the operation cost thereof are enormous and the pressure of the general filter press apparatus is about 15 kg / It is not realistic.

In the "method and apparatus for flocculation and dehydration of sewage sludge", the amount of the polymer flocculant added is divided by 75:25 ratio, first 75% is added, the initial flocc is crushed through high-speed stirring, and then 25% And a method of reducing the number of voids and free water in the flocs is proposed. However, this method only treats sludge with a water content of 80% at a water content of 77.4%, and does not provide final pressurized dehydration (filter press, etc.).

In the "treatment method of sewage sludge and the dehydrated cake produced therefrom", in the sludge treatment process of the sewage sludge, a carbon additive such as coal is mixed into the digested sludge to prepare a digested sludge mixture, And a carbon additive are mixed to prepare a centrifugally concentrated sludge mixture, and each of them is dehydrated, thereby reducing the water content of the dehydrated cake and improving the calorific value. However, the amount of the carbon additive added to the digested sludge is 2 to 10% by weight, the centrifugally concentrated sludge mixture comprises 60 to 70% by weight of the centrifugally concentrated sludge, 20 to 30% by weight of the waste paper solution and 10% by weight of the carbon additive, The solution is mixed with 98 to 99% by weight of water and 1 to 2% by weight of waste paper, so that the solid content of the sludge cake is increased to 4 to 5 times.

In Japanese Laid-Open Patent Application No. 1-111498 entitled " Method of dewatering sewage sludge ", a moisture content of 88% is obtained by adding 40% of wood chips to a solid content of condensed sludge as a dehydrating aid, and when this is dewatered under pressure of 5 kg / And is capable of self-burning in an incinerator. However, this is merely aimed at lowering the water content by adding a dry wood chip. As a result, the solids content of the sludge is increased about 1.4 times.

In the " sludge thickening and dewatering system and method of wastewater treatment process ", microbubbles are supplied to the secondary sludge introduced into the thickening section and aeration to aerate them, whereby the odor due to the stabilization of nitrogen contained in the secondary sludge And the load on the dehydrator is reduced to thereby reduce the dewatering efficiency and the amount of the flocculant used, as well as the stabilized nitrogen contained in the discharged sludge, so that it is advantageous that commercial use such as composting is easy without any post-treatment . However, this is about the process of aerating a concentrated slurry at a water content of 97%, and does not enhance the efficiency of the final dewatering process (sludge cake discharging process).

In the "Venturi pipe with micro bubble generator and sludge treatment device using the micro bubble generator", microbubbles are introduced into the sludge introduced into the concentrating part by using a micro bubble generator, so that the sludge agglomerates are finely crushed to be easily digested The effect of increasing the digestion efficiency of sludge by microorganisms and increasing the production of combustible biogas has been proposed. However, this does not increase the efficiency of the final dewatering process (sludge cake discharge process).

Patent Document 10-0413593 "Sludge Reduction and Recycling System and Method by Ozone Treatment" discloses a technique for ozonating bottom and wastewater sludge in order to reduce the amount of sludge generated. However, this is not a technique for increasing the dewatering efficiency of the sludge cake.

1. Patent Document 10-2015-0053993 "Dewatering Treatment Method and Dewatering Treatment Device of Sludge" 2. A method of re-dewatering the moisture content in a sludge cake to 40% level by mechanical mixing and compression in the presence of an additive (Japanese Patent No. 10-1237828) 3. Patent No. 10-0891023 "Method for coagulating and dewatering sewage sludge and apparatus therefor" 4. A method of treating sewage sludge and a dehydrated cake produced therefrom, 5. Japanese Unexamined Patent Publication No. 1-111498 entitled "Method of dewatering sewage sludge" 6. Open Patent 10-2017-0116591 "Sludge Concentration and Dewatering System and Method in Wastewater Treatment Process" 7. Patent No. 10-1162533 entitled " Venturi tube equipped with micro bubble generator "and sludge treatment device using the same 8. Registration No. 10-0413593 "Sludge Reduction and Recycling System by Ozone Treatment and Method Thereof"

An object of the present invention is to provide a method for increasing sludge dewatering effect by a pressure dewatering device while minimizing energy consumption. For this purpose, a method of forming a slurry discharged through various treatment processes (sedimentation, biological reaction, concentration, microbial digestion, chemical treatment, etc.) on wastewater can be formed in a state in which pressurized dehydration can be performed well.

Conventionally, there is a case in which the water content reaches 63 ~ 66% through the dehydration treatment of the wastewater sludge. However, the reason why further dehydration is difficult is because the moisture content in the microorganism body in the wastewater sludge reaches about 75%.

In the present invention, in order to further lower the water content of the wastewater sludge,

(1) weakening or damaging the cell wall or cell membrane of microorganisms in wastewater sludge,

(2) further breaking the cell wall or cell membrane to discharge the intracellular water out of the body,

(3) Ensure passage through which the water exiting the cell exits the sludge cake.

For the above-mentioned operation, the present invention provides a process for producing a sludge-containing sludge, comprising the steps of: (a) transferring stored and discharged sludge through one or more treatment steps of sedimentation, biological reaction, concentration and digestion treatment to wastewater; (b) injecting an inorganic coagulant first providing a cation before injecting a foaming oxidant into a path (hereinafter referred to as 'transport path') for transporting in the direction of the pressurizing and dewatering facility; And (c) injecting a foaming oxidizing agent, wherein the cell wall or cell membrane of the microorganism in the sludge is weakened or destroyed by the foaming oxidizing agent, and in the sludge squeezing process by the pressurizing and dewatering equipment, The cell wall or cell membrane expands and breaks in the direction of bubbles generated by the foaming oxidizing agent and the bubbles are discharged to the outside of the sludge in the pressing process to form a drainage passage, To thereby lower the water content to 60% or less.

Further, the surfactant may be injected together with the foamable oxidizing agent, and air bubbles having an amount exceeding the solubility may be injected together with the oxidizing agent.

In addition, the polymer flocculant may be injected before injecting the foamable oxidant into the transfer path.

According to the system and method provided by the present invention, the following effects can be expected.

1. The addition of a surfactant to the sludge before entering the pressurized and dewatered process promotes the dissolution or destruction of the cell wall or cell membrane of the microorganisms in the sludge.

2. By injecting air bubbles together with the surfactant, a drainage passage is formed in the sludge, thereby improving the dewatering efficiency of the sludge cake by the pressure dewatering device.

3. The dispersibility of the bubbles is improved by the surfactant.

4. By adding a foaming oxidizing agent such as ozone or hydrogen peroxide to the sludge before entering the pressurized and dewatered process, the cell wall or cell membrane of the microorganism in the sludge is broken, and the cell liquid can be dehydrated.

5. In order to lower the water content of the sludge cake to be finally discharged, it is necessary to increase the volume of the sludge by adding heat energy or various additives to the sludge cake, or to improve the pressure of the pressure dewatering facility, The invention can be applied simply.

6. The final sludge cake is self-combustible in the incinerator because the water content is lowered to less than 60%.

1 schematically shows a wastewater treatment facility.
FIG. 2 shows the concept that the cell wall or cell membrane of the microorganism in the sludge is broken by bubbles and the discharged body fluid is discharged into a drainage passage formed by bubbles.
3 shows the concept of the drainage passage in the sludge formed by bubbles.
Fig. 4 shows various embodiments of the oxidizer device applied to the present invention.

The present invention relates to a pressurized dehydration treatment method of lowering the water content of wastewater sludge.

The generalized wastewater sludge pressure dewatering process will be briefly described with reference to the conceptual diagram of the wastewater treatment facility of FIG. The wastewater flowing into the wastewater treatment facility is removed by sedimentation of heavy materials such as earth and sand from the gypsum (100), and various organic matter and inorganic substances are precipitated by floatation and coagulation in the first sedimentation material (200). (The sedimentation material or the water existing thereon after the solid material is precipitated in the initial sedimentation tank) can be sent to the final sedimentation material 400 and the sedimented slurry is sent to the biological reaction tank 300 or the concentration tank 500 .

The slurry having a large organic component is transferred to the bioreactor 300 to decompose the organic component using microorganisms (mainly aerobic microorganisms in this process). The treated water in the bioreactor 300 is settled in the final settling tank 400, the treated water is discharged after sterilization, and the settled slurry is concentrated in the centrifugal concentrator 700 and transferred to the slurry storage tank 800. When the organic substance in the slurry settled in the initial sedimentation tank 200 is small, the slurry is transferred to the concentration tank 500, is concentrated, is transferred to the digester 600, and is then digested by the microorganism. In this process, anaerobic microorganisms are generally used to generate methane gas and the methane gas is used as fuel. When the slurry having undergone the concentration process is transferred to the digester 600, a heat exchanger 610 is used for temperature control when necessary. The digested slurry is again conveyed to the sludge storage tank 800.

When the sludge is supplied from the sludge storage tank 800 to the pressurized and dewatered facility 1000, necessary medicines are injected using the medicament injection equipment 900 and the dehydration is performed. The effluent discharged during dehydration is transferred to the pre-stage equipment (the first settling tank or concentrator or bioreactor or the appropriate place in the digester) and the dehydrated sludge cake is disposed of. As the pressurizing and dewatering apparatus 1000, a belt press, a filter press, or the like can be applied. In the case where moisture in the sludge is trapped in solid matter, dehydration can not be performed properly.

The present invention relates to a method for pretreating sludge transferred to a final dewatering facility of a sewage treatment facility, comprising the steps of: (a) discharging the sludge through one or more treatment steps of sedimentation, biological reaction, Dewatering facility 1000 to the pressurized and dewatered facility 1000, (b) transferring the foamable dewatering facility 1000 to the pressurized and dewatered facility 1000, (C) injecting a foamable oxidizing agent,

The cell walls or cell membranes of the microorganisms in the sludge are weakened or destroyed by the foamable oxidizing agent and the cell walls or cell membranes of the remaining microorganisms in the sludge in the sludge squeezing process by the pressure dewatering apparatus 1000 And the water bubbles are discharged to the outside of the sludge during the squeezing process so that the water content of the sludge cake finally discharged through the pressure dewatering equipment 1000 is lowered to 60% A method for treating sludge before dehydration ".

The transfer path generally refers to the inlet of the dewatering apparatus connection pipe 1110, the dewatering apparatus connection pipe 1110, and the like. A foamable oxidizing agent such as hydrogen peroxide or ozone may be added to the sludge conveyed toward the pressurizing and dewatering apparatus 1000 in terms of destroying the cell wall or cell membrane of the microorganism in the sludge. The foamable oxidizing agent dissolves or thinens the cell wall or the cell membrane of the microorganisms in the sludge so that the sludge is easily discharged, thereby improving the dewaterability of the sludge. Particularly, when hydrogen peroxide is added, hydrogen peroxide bubbles are generated while destroying the cell wall or cell membrane of the microorganisms in the sludge. The hydrogen peroxide bubbles generated in this way cause deformation of the cell wall or cell membrane due to volume change in the pressurized and dewatered process for the sludge so that the hydrogen peroxide bubbles are discharged by the pressurization and the drainage passage is formed in the sludge cake.

[Fig. 2] shows a concept that the cell wall or cell membrane of the microorganism in the sludge is broken by bubbles, and the discharged body fluid is discharged into a drainage passage formed by bubbles. As shown in Fig. 2 (a), when there is no bubble in the sludge, there is almost no change in volume even when the sludge is pressurized. However, as shown in FIG. 2 (b), when there is air bubbles in the sludge, the volume of the air bubbles is reduced when the sludge is pressurized, and the cell wall or cell membrane expands and breaks in the air bubble direction. The intracellular fluid flows out through the broken cell wall or cell membrane and is discharged along the drainage passage formed by the discharge of the bubbles in the sludge squeezing process.

The foamable oxidizing agent may be introduced into the inlet of the dewatering apparatus connecting pipe 1110 through a chemical injection pipe 903 connected to the inside of the sludge storage tank 800 in the chemical injection facility 900 And indirectly connected to the connection pipe), a chemical injection pipe 901 connected to the diffusion device 1100 or a chemical injection pipe 902 connected directly to the pressure dewatering device 1000 can be injected into the sludge (Direct communication system). In addition, a surfactant may be injected into the transfer path. The surfactant can be injected through the drug injection pipes 901, 902, and 903, which are directly or indirectly connected to the dehydrating apparatus connection pipe 1110.

The surfactant makes the cell walls or cell membranes of the microorganisms in the sludge thin to easily break the cell wall or cell membrane. The microorganisms contained in the sludge confine the cell fluid in the cell wall or the cell membrane, and this cell fluid is one of the reasons why the water content of the sludge cake is not lowered. Conventionally, there has been a method of enhancing the digestion efficiency by using organic substances in the sludge as food for microorganisms in the digestion tank 600 through addition of chemicals in the digestion tank 600. However, even if this is done, finally the cell wall or cell membrane of the newly- The problem that does not exist exists. Therefore, the cell wall or cell membrane of the microorganism in the sludge is made thin by the surfactant, and the cell wall or the cell membrane is destroyed by cell wall deformation caused by the bubbles formed by the foam oxidizing agent when the sludge is pressurized, To reduce the water content. When the surfactant is applied together with the foaming oxidizing agent, the bubbles formed by the foaming oxidizing agent are evenly dispersed in the sludge, thereby preventing the bubbles from being counted before the pressurizing and dewatering step.

Bubbles formed by the air diffuser 1100 can be injected into the transfer path. The effect of damaging the cell walls or the cell membrane of the microorganisms in the sludge by the air bubbles formed by the air diffuser 1100 is as described above, and as shown in FIG. 3, a drainage passage by bubbles is formed in the sludge This makes it easier to form a state in which the water entrapped in the solid part can be easily discharged when the pressure is applied to the sludge through the pressurizing and dewatering equipment 1000. The air bubbles formed by the air diffuser 1100 have an advantage over air bubbles formed by the foaming oxidant for a long period of time. The step of injecting the bubbles proceeds sequentially with the injection of the surfactant or after the injection of the surfactant, so that the dispersibility of the bubbles can be improved by the surfactant.

Referring again to FIG. 1, the diffuser 1100 can be installed in the middle of the dewatering equipment connection pipe 1110 to inject air bubbles. That is, the dewatering facility connection pipe 1110 for transferring the stored sludge from the sludge storage tank 800 toward the pressurized dewatering apparatus 1000 through at least one of precipitation, biological reaction, concentration, and digestion treatment for the wastewater The air diffuser 1100 is provided. In order to inject air bubbles into the air diffuser 1100, a micro bubble generator may be introduced. In order to minimize the energy requirement, air is sucked through the process of supplying compressed air through the air compressor 1200 or using Bernoulli's principle It is preferable to be constructed so as to be crushed by a fine particle in the process of being dried.

FIG. 4 shows various embodiments of the air diffuser 1100. The air diffuser 1100 is a device for injecting air into the dewatering equipment connecting pipe 1110 for moving the sludge to the dewatering facility. The air diffuser 1100 includes a micro-hole drilling machine The air introduced through the porous material portion formed of the porous material may be supplied in the form of fine bubbles. Hereinafter, the micropores or the porous material forming unit formed on the channel of the dewatering apparatus connecting pipe 1110 will be referred to as an air diffusing unit 1120. An air introducing pipe 1130 is connected to the dehydrating equipment connecting pipe 1110 and the air introducing pipe 1140 is connected to the air introducing pipe 1130. The air diffusion portion 1120, the air guide portion 1130 and the air inlet pipe 1140 are common components of the embodiments of the diffuser 1100 shown in FIG.

(A) of FIG. 4 shows an embodiment of a diffuser 1100 configured to supply compressed air provided by an air compressor 1200 to the air diffuser 1120. Therefore, one end of the air inlet pipe 1140 is communicated with the air compressor 1200, and the other end is communicated with the air guide part 1130.

(B) of FIG. 4 shows a flow control unit 1160 installed inside the dewatering apparatus connecting pipe 1110 and in the section where the air diffusion unit 1120 is formed to reduce the cross-sectional area of the flow path through which the sludge flows, It is. The flow control unit 1160 may be formed as a streamlined body to lower the flow resistance, and a spiral bent flow guide plate 1170 may be installed at the head to rotate the sludge in a spiral manner. In this case, the air diffuser 1100 may be configured to receive the compressed air from the air compressor 1200, but without connecting the air inlet pipe 1140 to the air compressor 1200, the flow controller 1160 (Air in the air) may be sucked through the air inlet pipe 1140 by a negative pressure inside the dewatering equipment connecting pipe 1110 which is generated while the flow rate of the sludge moves at a high speed.

(C) of FIG. 4 shows a configuration in which the diameter of the section where the air diffusion unit 1120 is formed in the dewatering apparatus connecting pipe 1110 is narrowed so that the pressure of the corresponding section is lowered, Is an embodiment of an air diffuser configured to be sucked through tube (1140). If all of the air injected through the air diffuser 1100 is dissolved in the sludge, it is impossible to obtain the desired effect of the present invention, so it is important to inject the air amount exceeding the solubility.

On the other hand, the bubbles can be dispersed by applying a rotational force to the sludge into which the bubbles have been injected. Specifically, an inline mixer 1150 may be installed in the dewatering apparatus connecting pipe 1110 to apply a rotational force to the sludge injected with bubbles. Before the foaming oxidizing agent is injected into the transfer path, the inorganic flocculant for providing the cation may be injected first so that the organic matter in the sludge may be flocculated. Examples of the inorganic coagulant include ferric chloride, ferric sulfate, aluminum sulfate, polyaluminum chloride, and the like.

Since the state of the sludge before dehydration to which the present invention is applied is a state in which sedimentation, biological reaction, concentration, digestion treatment and the like have already been carried out so that the water content is already about 98%, the organic matter existing in the anion state in the water is aggregated with the inorganic flocculant will be. In addition, the polymer flocculant may be injected before the foaming oxidant is injected into the transfer path. The polymer flocculant is advantageous for aggregating organic substances far away because the molecular weight is large. The inorganic flocculant or the polymer flocculant may be selectively applied according to the state of the sludge before dewatering. Of course, it does not exclude the condition of mixing both.

Hereinafter, the effects of the present invention will be described together with experimental data.

[Example 1]

200 ml of ferric chloride (38% solution, specific gravity 1.4) was added to 20 kg of sludge (concentration 2.2%) and stirred for 2 minutes. Hydrogen peroxide (35% solution) was added as a foaming oxidizing agent After stirring, the mixture was injected into the pilot pressure dewatering device (filter press) at a pressure of 6 kg / cm2 using a pump, and dehydrated at a pressure of 15 kg / cm2 for 16 minutes by the pressure dewatering device. After dewatering, the cake was sampled and dried at 110 ° C for 15 hours, and the water content was measured.

As shown in the graph 1 below, the moisture content of the sludge cake discharged in the test example in which hydrogen peroxide was not added was 65.5%, but when the 35% hydrogen peroxide solution was added at 0.125% of the sludge weight, the water content of the discharged sludge cake 54%. However, even when the dose of the 35% hydrogen peroxide solution was doubled, the water content of the sludge cake discharged was not large.

[Graph 1]

[Example 2]

200 ml of sludge (1.4% by weight of sludge) was added to 20 kg of sludge (concentration 2.2%) and stirred for 2 minutes. Sodium laurylsulfate (SLS, 90% (35% solution) was added in an amount of 0.125% based on the weight of the sludge and stirred for 1 minute. Then, the solution was poured into a pilot pressure dewatering apparatus using a pump 6 kg / cm < 2 >, followed by dehydration for 16 minutes at a pressure of 15 kg / cm < 2 > After dewatering, the cake was sampled and dried at 110 ° C for 15 hours, and the water content was measured.

[Graph 2]

In Example 1, when the amount of the hydrogen peroxide solution was increased by 35%, there was no visible improvement in the water content of the sludge cake after dehydration. On the other hand, when the amount of sodium lauryl sulfate as the surfactant was 0.025% The water content of 1% was reduced significantly.

[Example 3]

The addition ratio of ferric chloride (38% solution, specific gravity 1.4) was adjusted to 20 kg (concentration 2.2%) of sludge as shown in Table 2 below and stirred for 2 minutes. Then, sodium lauryl sulfate (SLS, 90% (35% solution) was added thereto. After stirring for 1 minute, the mixture was injected at a pressure of 6 kg / cm 2 using a pump into a pilot pressure dewatering device, and then the mixture was pressurized to 15 kg / Dehydrated for 16 minutes. After dewatering, the cake was sampled and dried at 110 ° C for 15 hours, and the water content was measured.

[Graph 3]

Even when the amount of the ferric chloride solution is lowered to 1.0% compared to 1.4% of the ferric chloride solution by the weight of the sludge, the addition of the surfactant, sodium lauryl sulfate and the 35% hydrogen peroxide solution, The water content of the sludge cake was reduced by 7.6%. In addition, under the condition that the addition amount of the sodium lauryl sulfate and the 35% hydrogen peroxide solution were the same, the water content of the discharged sludge cake was reduced by increasing the amount of the ferric chloride solution.

[Example 4]

200 ml of ferric chloride (38% solution, specific gravity 1.4) was added to 20 kg of sludge (concentration 2.2%) and stirred for 2 minutes. Then, the surfactant sodium laurylsulfate (SLS, 90% After stirring for a minute, hydrogen peroxide (35% solution) was added as shown in Table 3 below and stirred for 1 minute. Then, the mixture was injected into the pilot pressure dewatering device at a pressure of 6 kg / Cm < 2 > for 16 minutes. After dewatering, the cake was sampled and dried at 110 ° C for 15 hours, and the water content was measured.

[Graph 4]

The water content of the sludge cake after dewatering is the lowest at 52.6% when the amount of ferric chloride is 0.10% of SLS and 0.35% of the 35% hydrogen peroxide solution at the same condition of the sludge weight. When the amount of added 35% hydrogen peroxide solution or SLS is decreased The water content of the sludge cake increases somewhat.

[Example 5]

200 ml of ferric chloride (38% solution, specific gravity 1.4) was added to 20 kg of sludge (concentration 2.2%) and stirred for 2 minutes. Then, the surfactant sodium laurylsulfate (SLS, 90% Then, hydrogen peroxide (35% solution) was added as shown in the following table and stirred for 1 minute. The mixture was injected into the pilot pressure dewatering device at a pressure of 6 kg / cm2 using a pump, Dehydrated. After the dewatering, the sludge cake was sampled and dried at 110 ° C for 15 hours, and the water content was measured.

When the sludge is injected into the pressurized dewatering apparatus, a solid mat is formed on the inner surface of the filter while water leaks out. When the solid mat gradually becomes thicker, over-pressure is applied to the sludge injection. In the present invention, this process time is referred to as a sludge injection time, and when the sludge injection time in the state where SLS and 35% hydrogen peroxide solution are not added is 350 seconds, when 0.1% of SLS and 0.38% of 35% hydrogen peroxide solution are added, It was confirmed that the water content of the sludge cake was reduced by 13%, and the sludge injection time was also shortened to 189 seconds. It is considered that the sludge dehydration condition was improved by adding SLS and hydrogen peroxide solution. Even when the addition amount of SLS is reduced to 0.05% and the addition amount of 35% hydrogen peroxide solution is reduced to 0.25%, the effect of reducing the water content of the sludge cake and reducing the sludge injection time are still large.

[Graph 5]

[Table 5] and [Graph 6] below summarize the results of the experiment on the water content change of the sludge cake depending on the additive amount and the sludge pressure dehydration time. In the same condition, the water content of the sludge cake tended to decrease as the sludge pressurization and dewatering time increased, but SLS 0.025% and 35%, respectively, were higher than when the sludge pressurization and dehydration time was increased to 30 minutes without addition of SLS and 35% hydrogen peroxide solution. % Hydrogen peroxide was decreased to 9 minutes, the water content of the sludge cake was lower than that of the sludge pressurized water. Therefore, the addition of the SLS and the 35% hydrogen peroxide solution can shorten the time required for the sludge pressurizing and dewatering process.

[Graph 6]

In summary, as shown in [Table 6] and [Graph 7] below, it is possible to partially reduce the moisture content of the discharged sludge cake by increasing the pressurized dehydration time without adding the surfactant and the foaming oxidizing agent to the sludge before dehydration , The reduction of the water content of the sludge cake can be further increased while shortening the sludge injection time or pressurized dewatering time depending on the addition of the surfactant and the foaming oxidizing agent.

[Graph 7]

[Example 6]

200 ml of poly iron (ferric sulfate, 11% solution, specific gravity 1.4) was added to 20 kg of sludge (concentration 2.2%) and stirred for 2 minutes. Then, the surface active agent sodium laurylsulphate (SLS, 90%) and hydrogen peroxide The mixture was poured into a pilot pressure dewatering device at a pressure of 6 kg / cm 2 using a pump, and then subjected to a dehydration process at a pressure of 15 kg / cm 2 in a pressure dewatering device. After dewatering, the cake was sampled and dried at 110 ° C for 15 hours, and the water content was measured. As shown in Table 7 below, when the SLS 0.025% and 35% hydrogen peroxide solution 0.25% were added, the water reducing effect was significantly greater than 24% in the short pressing time.

The present invention has been described in detail with reference to the preferred embodiments. However, it should be understood that the present invention is not limited to the above-described embodiment, but may be modified and changed without departing from the gist of the present invention. The claims of the present invention thus include such modifications and variations.

[Description of Symbols]

100: Gypsum bed 200: First settling basin

300: Bioreactor 400: Final clarifier

500: Enrichment tank 600: Digester

610: Heat exchanger 700: Centrifugal concentrator

800: Sludge storage tank 900: Chemical filling equipment

901, 902, 903: chemical injection pipe 1000: pressure dewatering equipment

1100: Diffusion device 1110: Dewatering device connection pipe

1120: air diffusion part 1130: air guide part

1140: Air inlet pipe 1150: Inline mixer

1160: Flow control unit 1170: Flow guide plate

1200: air compressor

Claims (4)

A method for pretreating sludge transferred to a final dewatering facility of a sewage treatment plant,
(a) transferring the discharged and stored sludge from the sludge storage tank toward the pressurized dewatering facility through at least one of the following steps: sedimentation, biological reaction, concentration, and digestion treatment for wastewater;
(b) first injecting an inorganic coagulant to provide a cation before injecting the foaming oxidant into the path for transfer to the pressurizing and dewatering facility; And
(c) injecting a foaming oxidant into a path for transfer to the pressure dewatering facility; And
(d) squeezing the sludge by the pressurized dewatering facility in the presence of bubbles generated by the foaming oxidizing agent,
The cell walls or cell membranes of the microorganisms in the sludge are weakened or destroyed by the foamable oxidizing agent and the cell walls or cell membranes of the remaining microorganisms in the sludge are expanded in the direction of the bubbles generated by the foaming oxidizing agent during the sludge squeezing process by the pressure dewatering equipment And a water drainage passage is formed as the bubbles are discharged to the outside of the sludge during the squeezing process so that the water content of the sludge cake finally discharged through the pressure dewatering facility is reduced to 60% Sludge treatment method. The method according to claim 1, wherein the pathway is filled with a surfactant. The method according to claim 1, wherein the path is filled with bubbles in an amount exceeding the solubility by the air diffuser. The method according to any one of claims 1 to 3, wherein the polymer flocculant is injected before injecting the foamable oxidant into the path.

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