KR101405876B1 - Method for producing bio-gas using sludge reduction - Google Patents

Abstract

The present invention can reduce sludge and can increase the amount of manufactured biogas by supplying organic wastewater to an anaerobic digester after atomizing the organic wastewater in the process of passing the organic wastewater through a venturi tube to enhance digesting efficiency in the digester and enhance the concentration of dissolvable organic matters. A method for treating sludge according to the present invention comprises the steps of: supplying organic wastewater such as sewage and livestock manure to a water collection tank via a pretreatment process; supplying sludge wastewater, which has been precipitated in the water collection tank, to a sludge-solubilizing facility with a venturi tube; supplying the solubilized sludge wastewater to a flow-adjusting tank; supplying part of the sludge wastewater in the flow-adjusting tank to a digester; re-solubilizing the sludge wastewater in the digester by introducing the sludge wastewater into a facility and a tank for fast oxidation and sludge solubilization; supplying the sludge to a liquid fertilizer storage tank; transferring part of precipitated sludge among sludge wastewater in the liquid fertilizer storage tank to a solubilizing tank and supplying the rest to a purifying and discharging facility; and capturing biogas generated in the digester and discharging the biogas after purification.

Description

[0001] The present invention relates to a method for producing a biogas using sludge solubilization technique,

The present invention relates to a biogas production method using a sludge solubilization technique, and more particularly, to a method for producing a biogas by solubilizing sludge by using cavitation phenomenon of a venturi tube and converting the solidified organic material into a soluble organic material, A method of producing biogas using a sludge solubilization technique that can maintain an equal sludge solubilization ratio by increasing the biogas production in the digestion tank by increasing the concentration and by linking the completed waste liquid to the high-speed liquefaction and discharge system through rapid oxidation will be.

Generally, a large amount of organic matter is contained in sewage such as manure wastewater including sewage, domestic sewage, and the like, and microorganisms that ingest nutrients from such organic materials are proliferating while living in large quantities. It is a sludge that forms a lump that is a mixture of solids and water with the material.

Therefore, when sewage containing a large amount of organic matter is treated, sludge, which is a secondary product, is inevitably generated, and the ratio of organic matter to inorganic matter is known to be about 7: 3.

A typical sewage treatment apparatus includes a pretreatment tank for removing solid matter from wastewater by floating or precipitating in a short period of time, a bioreactor for decomposing organic matter using microorganisms, a sedimentation tank for sedimenting solids including sludge using gravity, A concentrating tank for concentrating the concentrated sludge at a high concentration, a digester for decomposing the concentrated sludge mainly using anaerobic microorganisms, a dehydrator for dehydrating the digested sludge, and the like.

In the biological treatment tank of the sewage treatment apparatus, organic matter is mainly decomposed by aerobic microorganisms, and the microorganism mass (also referred to as Bio-Floc) propagated by feeding the organic matter is subjected to a solid-liquid separation process in which it is separated from water in a sedimentation tank, The supernatant is discharged to the outside, and the precipitated sludge is caked and processed through concentration, digestion, and dehydration processes.

The TS (total solids content) of sedimentation sludge is about 0.5%, and TS is concentrated to 3-4% through the concentrating tank, which takes about 20 hours. Approximately 30% of the organic matter in the digester is decomposed and methane gas and carbon dioxide, which are combustible gases that can be used as fuel, are generated. It takes about 15 to 25 days.

The digested sewage sludge is finally dehydrated to a cake form in a dehydrator, and then treated by burial, incineration, marine dumping, etc. The cost of treating the solid sludge is 40 to 60% of the total sewage treatment cost Respectively.

The conventional wastewater treatment and sludge treatment processes require a lot of time and expense and require a lot of energy. In addition, since the environmental policy is being changed to landfill and marine dumping, the disposal of sludge is becoming more difficult, and the disposal of sludge is costly.

In addition, the excess sludge generated in existing sewage treatment facilities is composed of cells of microorganisms grown using organic matter. Since the characteristics of the cells are not easily decomposed, the reduction rate in the digestion tank is also low, which causes many problems.

Therefore, the mucous membrane forming the sludge particles and the internal water (present in the cell fluid of the cells) cause the lowering of the digestion efficiency and the lowering of the dehydration efficiency, and also cause the increase of the amount of drug required for dehydration for cell destruction.

Therefore, introduction of the sludge intermediate treatment technology to improve the digestion efficiency, minimize the amount of sludge generated, maximize the biogas production, and improve the dewatering efficiency is necessary

Conventional treatment techniques have been undergoing pre-dehydration treatment to increase the dehydration property to reduce the sludge volume at the final stage. In this sludge treatment process, after the wastewater flows into the first settling basin, the treated water that has undergone biodegradation through the bioreactor is moved to the final settling tank and solid-liquid separated. Thereafter, the water in the upper part of the settling tank is discharged, and the settled sludge is concentrated through the concentration tank, and after the medicine is added in the digestion tank, it is dehydrated through the dehydrator. The dehydrated cake is buried or incinerated.

However, secondary environmental pollution problems due to the chemical treatment process may occur, and the concentration efficiency of the sludge concentration tank, the digestion efficiency of the digestion tank should be lowered, and the polymer flocculant should be used when the sludge is improved. Since the amount of sludge to be added and disposal is increasing due to dehydration after machine concentration, the development of techniques for physical treatment before dewatering is actively under way.

Prior art related to conventional sludge reduction and biogas production is disclosed in Korean Patent Registration No. 10-0603990 entitled " Sludge Reactor Using Ultrasonic Cavitation to Enable Sludge Reduction and Biogas Extraction "(registered on July 14, 2006) , The sludge is treated by using a sludge reactor arranged so as to correspond to the U-shaped ducts in the longitudinal direction, and the treated sludge is transported, whereby the efficiency of the digester is increased and the digestion days are relatively reduced, It is possible to treat the bulking sludge and to increase the dewatering efficiency of the sludge and in the case where the sludge reactor is clogged during the treatment of the sludge, the sludge reactor is being treated in the reverse direction by supplying the sludge in the reverse direction in the ultrasonic reactor It is possible to prevent clogging of the sludge, A to increase the saengryang using a fire extinguishing gas production of biogas, and the biogas production is one to take advantage of energy efficient by providing a source of air-conditioning and electricity.

Other prior art related to conventional sludge reduction and biogas production include organic waste as shown in Korean Registered Patent Publication No. 10-0770626 entitled " Organic Waste Biogas Recovery Device "(registered on October 22, 2007) An incoming pH adjusting vessel; A solubilization treatment tank connected to the pH adjusting tank and having an ultrasonic vibrator inside; A mixed storage tank connected to the solubilization treatment tank to mix food waste leachate; An acid production reactor in which the organic waste introduced from the mixed storage tank is heated; A solid-liquid separator connected to the acid production reaction tank and performing solid-liquid separation through a separation membrane provided therein; And a biogas generating tank connected to the solid-liquid separator, the biogas generating tank being filled with microorganisms therein; Lt; / RTI >

Conventionally, as described above, biogas is produced using the solubilization method of sludge using ultrasonic waves. However, in the case of a tank or a digester having a large volume, it is difficult to uniformly apply the ultrasonic vibration function to each part, .

In addition, the existing sludge solubilization method has a disadvantage that it is difficult to utilize it as industrial energy because the amount of generated biogas is insufficient.

Korean Registered Patent Publication No. 10-0603990 entitled "Sludge Reactor Using Ultrasonic Cavitation to Enable Sludge Reduction and Biogas Extraction" (Registered on July 14, 2006) Korean Registered Patent Publication No. 10-0770626 entitled "Organic Waste Biogas Recovery Device" (registered on October 22, 2007)

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and its object is to provide a method and apparatus for converting anaerobic digestion efficiency by converting sludge of organic wastes into soluble organic matter using cavitation phenomenon, The present invention provides a method of producing biogas using the sludge solubilization technique with improved structure.

According to an aspect of the present invention, there is provided a method for treating organic wastewater comprising the steps of: supplying organic wastewater such as sewage, livestock manure,

Supplying organic wastewater in the water collecting tank to a sludge solubilizing facility having a venturi pipe to solubilize the sludge,

Supplying the solubilized sludge wastewater into a flow rate regulator,

Supplying a part of the sludge wastewater in the flow rate control tank into the digester;

Introducing the sludge wastewater in the digester into the solubilization facility and the tank to re-

Supplying the re-solubilized sludge wastewater into a liquid storage tank,

Transporting a part of the settled sludge in the sludge wastewater in the liquid storage tank to a solubilization tank and supplying the remainder to a purification tank;

Collecting and purifying the biogas generated in the digester, and discharging the biogas to the outside.

The sludge solubilization facility injects sludge wastewater into a main body having a space portion in which the sludge wastewater is stored, passes the introduced sludge wastewater through a pipe at a lower portion of the main body, passes through the venturi pipe, and is atomized using cavitation phenomenon , And the process of re-charging it into the main body.

It is preferable to measure the pressure inside the venturi pipe by a pressure gauge and feed back the amount of the sludge wastewater flowing into the venturi pipe according to the pressure change in the venturi pipe 100.

When the internal pressure of the venturi pipe is lower than a set value, it is preferable to supply high-pressure air into the venturi pipe.

Further comprising the step of maintaining the temperature of the sludge wastewater at 35 to 45 캜 by utilizing the cavitation phenomenon of the sludge wastewater passing through the venturi pipe (100) of the sludge solubilization facility.

First, according to the present invention, organic wastes and sludge are passed through a venturi pipe (100) of a sludge solubilization facility to solubilize sludge using cavitation phenomenon to convert solidified organic matter into dissolved organic matter, thereby increasing the concentration of dissolved organic matter having a high biodegradation rate The sludge can be reduced by minimizing the organic matter content of the final sludge by maximizing the organic matter decomposition rate of the solubilized transport sludge and increasing the anaerobic digestion efficiency by increasing the dissolved organic oxygen concentration (SCOD: Soluble Chemical Oxygen Demand) Thereby increasing the reproductive density of the organic acid bacteria and increasing the activity of the methane bacteria, thereby having a beneficial effect of increasing the amount of methane gas generated as a biogas.

Second, when the internal pressure of the venturi pipe 100 is lower than a preset value, the present invention provides a phenomenon in which the interior of the venturi pipe 100 is clogged with sludge by supplying high-pressure air into the venturi pipe 100 It has an advantage that can be prevented.

Third, there is an advantage in that the amount of biogas generated due to solubilization of sludge compared to conventional sludge reduction methods can be increased and the sludge wastewater can be liquefied at high speed after the anaerobic digestion process.

In addition, the present invention has an advantage that raw material energy required for power of a conventional power plant can be greatly reduced by supplying an increased biogas to an own biogas generator.

1 is a flow chart sequentially showing a method for producing biogas using sludge solubilization according to the present invention.
2 is a schematic view showing a treatment process to which a biogas production method using sludge solubilization of the present invention is applied.
3 is a block diagram showing the structure of a venturi pipe of the sludge solubilization facility of the present invention.
FIG. 4 is a graph showing a change in suspended solids, a total organic substance concentration, and a dissolved organic substance concentration by time of the sludge reduction process of the present invention.
FIG. 5 and FIG. 6 are graphs and bar graphs comparing the biogas production method of the present invention with methane gas generation amount of raw organic wastes.

In the present invention, organic wastewater is passed through a venturi pipe to be atomized and then fed into an anaerobic digestion tank to increase the digestion efficiency in the digestion tank to increase the concentration of dissolved organic substances, thereby reducing sludge and increasing the production amount of biogas .

1 to 3, organic wastewater such as sewage and livestock manure is supplied into a collecting tank through a pretreatment process (S1), and organic wastewater and organic wastewater are collected in a collecting tank. (S2), the solubilized sludge wastewater is supplied into a flow rate regulating tank (S3), and the sludge wastewater in the flow rate regulating tank is supplied to the anaerobic digestion tank by a predetermined amount (S4) After the digestion process is completed, the waste liquid is introduced into a high-speed oxidation and solubilization facility (S5). The high-speed liquefaction is performed through high-speed oxidation and then supplied to the liquid storage tank (S6) (S7). In addition, the biogas generated in the digester is collected and purified After it, including the step of discharging (S8) to the outside.

Referring to FIG. 1, the treatment process of sludge is performed in the order of pretreatment of wastewater → collection tank → sludge solubilization facility → flow control tank → digester tank → high-speed oxidation and sludge solubilization facility → liquid storage tank → purification discharge facility, After the sludge is conveyed to the solubilization tank, the sludge is conveyed to the sludge solubilizing facility again.

In addition, the biogas treatment process can be performed by collecting and purifying the methane gas generated in the upper part of the digester (anaerobic), supplying the purified biogas to the own biogas generator, .

Referring to FIG. 2, there is provided a water collecting tank, a sludge solubilizing facility, a flow rate adjusting tank, an anaerobic digestion tank, a high-speed oxidation and solubilization facility, a liquid storage tank, .

The anaerobic digestion tank of the present invention has a function of collecting methane gas generated on the upper side and sending it to the outside, and supplying the digested wastewater to the lower side of the anaerobic digestion tank.

The methane gas delivered to the outside can be recycled as a power source for the power generation facility by supplying purified biogas gas to the biogas power generator after purification through a separate purification facility and then recovering the waste heat through hot water recovery through a heat exchanger.

The solubilization tank may receive the sludge from the sludge solubilization facility or return the sludge to the sludge solubilization facility before the purification discharge.

The present invention increases solubility chemical oxygen demand (SCOD) so that sludge is solubilized using cavitation phenomenon of organic wastewater and sludge by sludge solubilizing facility to convert solidified organic matter into dissolved organic matter to increase biodegradation rate Thereby increasing the anaerobic digestion efficiency, thereby increasing the reproductive density of the organic acid bacteria, thereby increasing the activity of the methane bacteria, thereby increasing the amount of methane gas generated as a biogas.

The sludge solubilization facility includes a main body having upper and lower portions connected to each other by a pipe 400 and having a space portion in which sludge wastewater is stored, a pump disposed at a lower portion of the main body for feeding sludge wastewater into the pipe 400, 400 and a venturi pipe 100 that atomizes the sludge wastewater pumped along the inside of the pipe 400 by a pump using the Bernoulli principle.

Accordingly, the high-speed oxidation and sludge solubilization facility injects the sludge wastewater into the main body having the space portion where the sludge wastewater is stored, and transfers the sludge wastewater into the venturi pipe 100 while transferring the charged sludge wastewater through the pipe 400 from the lower portion of the main body. And then the air is injected into the body after it is atomized using a cavitation phenomenon.

As a result, the production of biogas due to solubilization of the sludge is increased and the sludge wastewater can be liquefied at high speed after the anaerobic digestion treatment.

In addition, the sludge tank can introduce the excess sludge into the sludge solubilization facility or take out the dehydrated solid after discharging it.

The sludge wastewater passing through the venturi pipe 100 is maintained at a temperature of 35 to 45 ° C by using the cavitation phenomenon of the venturi pipe 100 to maintain the sludge solubilization ratio (dissolved organic matter concentration / total organic matter concentration) Can be improved.

Accordingly, the present invention can provide an effect of buffering the impact load due to a change in property of the wastewater flowing in the winter season through the maintenance of the temperature.

If the temperature of the sludge wastewater is lower than 35 ° C, it is impossible to buffer the impact load due to changes in properties of the wastewater flowing in the winter season. If the temperature exceeds 45 ° C, it is difficult to maintain the temperature of the sludge wastewater. .

3, the venturi pipe 100 is formed with an inlet 110 through which sludge wastewater flows in one side, an outlet 120 through which sludge wastewater in an atomized state flows out from the other side, And a narrowed neck region is formed.

The sludge wastewater passing through the venturi pipe (100) is filled with gas components dissolved in the sludge at the neck part (130) of the venturi pipe (100) and the bubbles are destroyed at the point where the pressure is restored Cavitation occurs. When cavitation occurs in the sludge, energy such as shear force and jet stream generated in the process of destroying the bubbles becomes a state in which the sludge, which is a mass of microorganisms, is atomized into small lumps and is easily digested.

The venturi pipe 100 is provided with a pressure gauge 200 for measuring the pressure in the venturi pipe 100 near the outlet 120.

The pressure gauge 200 functions to apply the internal pressure of the venturi pipe 100 to the control unit 600 while the control unit 600 controls the opening degree of the valve 320 provided in the pipe 400 310, respectively.

When an electrical signal output from the pressure gauge 200 is applied to the control unit 600 side, when a change in the internal pressure of the venturi pipe 100 is out of a predetermined range, a control signal is applied to the adjustment motor 310, The inflow amount of the sludge wastewater flowing into the inlet 110 of the sludge wastewater is feedback controlled.

That is, when the pressure in the venturi pipe 100 exceeds the set range value, the opening angle of the valve 320 is reduced to reduce the inflow amount of the sludge wastewater supplied to the inlet 110 side of the venturi pipe 100, It is preferable that the opening angle of the valve 320 is enlarged to increase the inflow amount of the sludge wastewater supplied to the inlet 110 of the venturi pipe 100.

The high-speed oxidizing and sludge solubilization facility is a device for solubilizing high-speed oxidation and sludge as measured from a pressure gauge 200 provided at the outlet 120 of the venturi pipe 100 when the sludge is clogged in the neck of the venturi pipe 100 A compressor 500 for supplying high-pressure air to the inside of the venturi pipe 100 is connected to each part of the venturi pipe 100 in order to solve the internal clogging state of the venturi pipe 100, Respectively.

When the pressure value measured by the pressure gauge 200 is lower than the value set in the control unit 600, the compressor 500 introduces high pressure air into the venturi pipe 100 according to a control signal of the control unit 600 And functions to eliminate the clogged state in the venturi pipe (100).

Hereinafter, the results of the tests performed by the sludge solubilization method of the present invention are shown.

In Table 1, sludge and solubilized sludge are classified into suspended solids (SS), total organic oxygen concentration (TCOD) and dissolved organic oxygen concentration (SCOD) (Dissolved organic matter concentration / total organic substance concentration) of the test substance were shown.

division Raw sludge Solubilized sludge Suspended substance (mg / l) 65,000 46,800 Total organic matter concentration (mg / l) 151,000 159,628 Dissolved organics concentration (mg / l) 50,000 86,285 Solubilization rate 33.1% 54.1%

 As shown in Table 1, it can be seen that the sludge is reduced through the sludge weight reduction process of the present invention, and the solubilization ratio is greatly increased.

FIG. 4 is a graph showing a change in suspended solids, a total organic substance concentration, and a dissolved organic substance concentration by time of the sludge reduction process of the present invention, and these values are shown in Table 2 below.

division Raw wastes 30 minutes 60 minutes 90 minutes 120 minutes 150 minutes 180 minutes Suspended substance (mg / l) 65,000 61,560 58,688 55,000 51,680 49,000 46,800 Total organic matter concentration (mg / l) 151,000 153,416 155,831 156,866 158,160 158,670 159,628 Dissolved organics concentration (mg / l) 50,000 56,500 62,100 67,000 72,600 79,000 86,285

In Table 2, the dissolved organic matter concentration and the total organic matter concentration are increased as the suspended substances are reduced and the sludge is reduced as time passes.

5 and 6 are graphs and bar graphs showing the amount of methane generated in the organic waste of organic wastewater (based on 1 ton) and the solubilized waste solubilized by the method of the present invention, It can be seen that the generation amount is generally high.

Accordingly, the present invention solves sludge using cavitation phenomenon by passing organic wastes and sludge through a venturi pipe (100) of a sludge solubilization facility to convert solidified organic matter into dissolved organic matter, thereby increasing the concentration of dissolved organic matter having a high biodegradation rate Thereby maximizing the organic matter decomposition rate of the solubilized transport sludge, minimizing the organic matter content of the final sludge and reducing the amount of sludge, and increasing the amount of biogas generated in the process.

100: Venturi tube 110: Inlet port
120: outlet 130: neck
200: pressure gauge 310: regulating motor
320: valve 400: piping
500: compressor 600: control unit

Claims (5)

A step of supplying organic wastewater such as sewage, livestock manure or the like into a collection tank through a pretreatment process,
Supplying organic wastewater in the water collecting tank to a sludge solubilizing facility having a venturi pipe to solubilize the sludge,
Supplying the solubilized sludge wastewater into a flow rate regulator,
Supplying a part of the sludge wastewater in the flow rate control tank into the digester;
Introducing the sludge wastewater in the digester into the solubilization facility and the tank to re-
Supplying the re-solubilized sludge wastewater into a liquid storage tank,
Transporting a part of the settled sludge in the sludge wastewater in the liquid storage tank to a solubilization tank and supplying the remainder to a purification tank;
Collecting and purifying the biogas generated in the digestion tank, and discharging the biogas to the outside; and a method of producing biogas using the sludge solubilization technique. The method according to claim 1,
The sludge solubilization facility injects sludge wastewater into a main body having a space for storing the sludge wastewater, passes the sludge wastewater through a pipe (400) from the bottom of the main body, passes through the venturi pipe (100) Wherein the sludge solubilization process is repeatedly carried out in the main body after atomization using the sludge solubilization technique. The method of claim 2,
The pressure in the venturi pipe 100 is measured by the pressure gauge 200 and the amount of the sludge wastewater flowing into the venturi pipe 100 is feedback controlled in accordance with a change in the pressure inside the venturi pipe 100 A method of producing biogas using sludge solubilization technology. The method of claim 3,
Wherein the high pressure air is supplied into the venturi pipe (100) when the internal pressure of the venturi pipe (100) is lower than a set value. The method according to claim 1,
Further comprising the step of maintaining the temperature of the sludge wastewater at 35 to 45 ° C by using the cavitation phenomenon of the sludge wastewater passing through the venturi pipe (100) of the sludge solubilization facility Way.

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