JP2003062421A - Biological desulfurization equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide biological desulfurization equipment having high desulfurization efficiency and capable of performing desulfurization while keeping the concentration of biogas. SOLUTION: Activated sludge is aerated in an aeration tank 20 when organic waste such as excretions, the sludge urine of a septic tank or the like is biologically treated. The aerated activated sludge is supplied to a desulfurization tank 10 from the aeration tank 20 and gas containing sulfide is passed through the activated sludge from the lower part of the desulfurization tank 10. Then, the activated sludge after desulfurization is drawn out of the drain port 40 provided to the lower part of the desulfurization tank 10 to be returned to the aeration tank 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a desulfurization apparatus, and more particularly to a biodesulfurization apparatus, a biogas power generation apparatus and a biodesulfurization method capable of desulfurizing while having a high desulfurization efficiency and maintaining a biogas concentration.

[0002]

2. Description of the Related Art A method of recovering biogas containing methane gas by fermenting human waste, septic tank sludge, garbage, etc. by a methane fermentation process which is one of anaerobic treatments, and using this as energy for power generation, etc. is used. Has been done. In such an anaerobic treatment, hydrogen sulfide is present in the biogas generated in the anaerobic fermentation, so it is necessary to remove it.

As a method for removing hydrogen sulfide existing in biogas generated in anaerobic fermentation, a water washing method,
An alkali absorption method and a removal method using an iron-based adsorbent are known. These methods have the following problems. First, the water washing method requires a large amount of water and requires treatment of absorbed hydrogen sulfide. Moreover, the removal of hydrogen sulfide tends to be insufficient. In the alkali absorption method, the amount of chemicals used increases, the running cost increases, and the absorbed hydrogen sulfide needs to be treated. Furthermore, NaO used in the alkali absorption method
Since H is a strong alkali, careful operation is required. In addition, the removal method using an iron-based adsorbent has a high running cost, and the adsorbent after adsorbing hydrogen sulfide is easy to generate heat or ignite, so that it is difficult to handle and its disposal is also difficult.

In recent years, in place of such a desulfurization method, a biodesulfurization method has been used in which hydrogen sulfide in a gas is removed by oxidizing and decomposing hydrogen sulfide by a microorganism. Here, the biological desulfurization is to remove hydrogen sulfide (H ₂ S) in the gas by utilizing an oxidation reaction by desulfurizing bacteria. This biological desulfurization process is an energy-saving process because it is at normal temperature and pressure, and can reduce the environmental load compared to conventional desulfurization methods.

[0005]

By the way, in the prior art, as shown in FIG.
As shown in FIG. 2, a method for biodesulfurization by introducing biogas such as methane gas generated by anaerobic fermentation and air or oxygen into a biodesulfurization tower 100 having a filler layer 101 to which desulfurizing bacteria are attached. Was used. But,
A large amount of air or oxygen must be supplied in order to proceed with biodesulfurization by this method, and there is a problem that the volume of the gas holder for storing biogas such as methane gas becomes large. Also, generate biogas from sludge,
When this is used as an energy source, there is also a problem that the biogas concentration decreases due to a large amount of air introduced for desulfurization, and sufficient heat energy cannot be generated.

Further, in the above-mentioned biodesulfurization method, oxygen required for biodesulfurization is supplied by introducing air or oxygen. However, since the oxidation reaction by the desulfurization bacterium is difficult to occur with gaseous oxygen, desulfurization is not possible. Easy to be incomplete. In order to solve this problem, Japanese Patent Laid-Open No. 9-262429 discloses
There is disclosed a biodesulfurization device that aerates the wastewater discharged from the biodesulfurization tower, and sprays concentrated water concentrated by membrane filtration of the aeration-treated solution to the biodesulfurization tower.

In this biodesulfurization apparatus, undecomposed hydrogen sulfide existing in wastewater is oxidatively decomposed by aeration. Further, this wastewater is saturated with oxygen in the aeration treatment liquid by aeration, and is an aeration treatment liquid containing a sufficient amount of dissolved oxygen. The aeration treatment liquid containing a sufficient amount of dissolved oxygen is concentrated by membrane filtration and then sprayed again into the desulfurization tower, so that the dissolved oxygen in the treatment liquid promotes biodesulfurization in the desulfurization tower. In addition, the microorganisms flowing out from the desulfurization tower are concentrated by membrane filtration, and are watered again to the desulfurization tower together with the aeration treatment liquid.

However, the filtration membrane used in this biodesulfurization device is required to have a capacity capable of concentrating microorganisms, and it is necessary to have a fine mesh. For this reason, it is clogged with impurities contained in the waste water from the desulfurization tower, so maintenance is time-consuming, and the replacement cycle of the filtration membrane is generally not so long, so the actual operating time of the desulfurization equipment is shortened. There was a problem. Moreover, since the replacement cost of the filtration membrane is also required, the running cost is also increased.

Further, in order to carry out membrane filtration efficiently, it is necessary to apply pressure to the wastewater from the desulfurization tower for filtration,
There is also a problem that energy for this is required and operating cost increases. Further, even if the aeration-treated solution is concentrated by membrane filtration, there is a limit to increase the density of desulfurizing bacteria, so that the desulfurization efficiency cannot be increased above a certain value. Therefore, the present invention has been made in view of the above, and an object thereof is to provide a biodesulfurization device, a biogas power generation device, and a biodesulfurization method, which have high desulfurization efficiency and can be desulfurized while maintaining a biogas concentration. And

[0010]

In order to achieve the above object, the biological desulfurization apparatus according to claim 1 is used for biological treatment of human waste, septic tank sludge, sewage sludge and other organic wastes by the activated sludge method. And a desulfurization tank for supplying activated sludge from the aeration tank and allowing a gas containing sulfide to pass through the activated sludge to remove the sulfide by a biological desulfurization action. And

This biodesulfurization device is designed to pass a gas containing sulfide through the activated sludge from the aeration tank to desulfurize it. Since the activated sludge has a high microbial density, it can be desulfurized more efficiently than when the microorganisms are dispersed in water. Further, this activated sludge sufficiently dissolves oxygen by aeration, so that the oxidation reaction of hydrogen sulfide is promoted. Further, unlike the conventional case, it is not necessary to perform membrane filtration of the waste water after desulfurization, so that the trouble of maintenance and inspection is not required and the reliability of the entire apparatus can be increased. Furthermore, since it is not necessary to supply air or the like in the desulfurization tank as in the conventional case, the volume of the gas after desulfurization hardly increases. Therefore, when the gas after desulfurization is stored, the gas storage facility such as the gas holder can be made small, and the space can be effectively used. Further, since the gas component after desulfurization hardly changes, when using the gas after desulfurization as a fuel, it is possible to obtain a high-quality fuel containing many effective components.

The biodesulfurization apparatus according to the present invention can be applied not only to desulfurization of biogas but also to desulfurization of exhaust gas from a thermal power plant or the like. Since activated sludge has a higher viscosity than water, it is preferable to use a pump such as a uniaxial screw pump or a spiral pump as a supply means for supplying activated sludge from the aeration tank to the desulfurization tank.

The biological desulfurization apparatus according to a second aspect of the present invention is the biological desulfurization apparatus, further comprising return means for returning the desulfurized activated sludge supplied to the desulfurization tank to the aeration tank. To do. This biological desulfurization device is designed to return the desulfurized activated sludge to the aeration tank again. For this reason, even if there is undesulfurized matter in the activated sludge, this activated sludge is aerated in the aeration tank and sufficiently dissolves oxygen. You can Further, by returning the activated sludge after desulfurization to the aeration tank, the microorganisms in the aeration tank can also be used for desulfurization. Due to these effects, the undesulfurized component is almost absent in this biodesulfurization device. The activated sludge in the aeration tank can be treated as it is in the water treatment facility.

A biogas power generator according to a third aspect of the present invention comprises a gas generator that anaerobically ferments organic waste to generate biogas, and human waste, septic tank sludge, sewage sludge and other organic waste. An aeration tank used for biological treatment by the activated sludge method, a desulfurization tank that passes a gas containing sulfide and removes the sulfide by a biological desulfurization action, and activated sludge in which oxygen is dissolved by aeration from the aeration tank To the desulfurization tank, a gas supply means for supplying the biogas to the activated sludge supplied to the desulfurization tank, and the desulfurized active sludge supplied to the desulfurization tank It is characterized by comprising a returning means for returning to the aeration tank, and a power generation means for generating electric power by using the desulfurized biogas as fuel.

In this biogas power generator, biogas generated by anaerobic fermentation of organic waste is passed through activated sludge supplied from an aeration tank to desulfurize, thereby operating power generation means to supply electric power. To do. When desulfurizing the biogas in this manner, it is not necessary to supply air or the like in the desulfurization tank as in the conventional case, so that the volume of gas after desulfurization hardly increases. For this reason, the gas holder for storing the gas after desulfurization can be made small, so that the entire power generation device can be made compact. Moreover, since the components of biogas after desulfurization hardly change, they can be used as a high-quality fuel with many active components in a power generation means, and electric power can be efficiently supplied.

In addition to power generation means for driving a generator by a gas engine or gas turbine, power generation means by a steam turbine driven by steam generated by combustion heat of biogas, or hydrogen from methane gas in biogas components. The present invention can be applied to a power generation unit that separates the fuel cell and supplies it to the fuel cell to supply electric power. Biogas can be generated by anaerobically fermenting organic waste.The organic waste used at this time is livestock manure, food processing wastewater sludge, kitchen refuse, sewage sludge and other solid waste. It is preferable to utilize shaped organic waste. In the anaerobic fermentation, it is necessary to adjust the water content of the organic waste, but if the solid organic waste,
This is because the water content can be adjusted simply by adding the water content, which is easy to adjust.

The biogas power generator according to a fourth aspect of the present invention is the biogas power generator, further comprising temperature adjusting means for adjusting the temperature in the desulfurization tank by the exhaust heat of the heat engine. And This biogas power generation device uses exhaust heat generated from power generation means such as gas engine power generation or fuel cell power generation for temperature control of a desulfurization device,
The temperature in the desulfurization tank is kept constant.

Desulfurizing bacteria having a desulfurizing action in the desulfurization tank are 30 ° C.
It grows before and after, and its growth activity declines when the temperature becomes low, and it die when the temperature is too high. For this reason, the desulfurization tank is heated in the winter when the temperature is low, and the desulfurization tank is cooled in the summer when the temperature is high, so that the temperature in the desulfurization tank is kept around 30 ° C. throughout the year. By doing so, desulfurization efficiency can be increased by vigorous growth activity of desulfurization bacteria, and stable desulfurization can be performed throughout the year. In addition, since the exhaust heat generated as a result of using biogas for power generation is used for adjusting the temperature of the desulfurization tank, the thermal efficiency of the entire system can be increased. Further, the temperature level of the exhaust heat of the power generation means is also an appropriate temperature level for keeping the desulfurization tank at about 30 ° C., so that the thermal energy can be effectively used.

As the temperature adjusting means, there is one that guides the exhaust heat of the power generating means to an exhaust heat recovery boiler or the like to generate steam, and uses the steam to heat the desulfurization tank. Further, there is one in which this steam is guided to an absorption refrigerator to generate cold water and the like, and this cold water is used for cooling the desulfurization tank.

The biological desulfurization method according to a fifth aspect of the present invention comprises the step of aeration when biologically treating human waste, septic tank sludge, sewage sludge and other organic wastes by the activated sludge method, and oxygen dissolved by the aeration step. A step of supplying the activated sludge to a desulfurization tank, and removing the sulfide by a biodesulfurization action by passing a gas containing a sulfide into the activated sludge.
It is characterized by having.

In this biological desulfurization method, the activated sludge from the aeration tank is supplied to the desulfurization tank, and a gas containing sulfide is passed through the activated sludge for desulfurization. Since the activated sludge has a high microbial density, it can be desulfurized more efficiently than when the microorganisms are dispersed in water. Further, unlike the conventional biological desulfurization method, it is not necessary to perform membrane filtration on the waste water after desulfurization, so that maintenance and inspection work is not required. Further, since it is not necessary to supply air or the like in the desulfurization tank as in the conventional case, the volume of the gas after desulfurization hardly increases and its components hardly change. Therefore, the facility for storing the gas after desulfurization can be made small, and since the gas after desulfurization has many effective components, a good quality fuel can be obtained.

In this biological desulfurization method, the activated sludge may be manually supplied to the desulfurization tank if the desulfurization tank is not so large in scale. Alternatively, the activated sludge may be carried from a human waste treatment facility or a livestock excrement treatment facility by a tank car or the like and supplied to a desulfurization tank. This method is effective when the desulfurization tank exists solely in the power plant or the like and the human waste treatment facility is not near the power plant.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail with reference to the drawings. The present invention is not limited to this embodiment. Further, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art.

(Embodiment 1) FIG. 1 is an explanatory view showing a biological desulfurization apparatus according to Embodiment 1 of the present invention. This biodesulfurization device is characterized in that the activated sludge in the aeration tank of the water treatment facility installed in the organic waste treatment facility is used for biodesulfurization. In the following description, a case where this biodesulfurization device is applied to desulfurization of biogas produced by the biogas generation device will be described.

FIG. 2 is an explanatory view showing an example of the biogas generator. This biogas generator is a biogas containing methane by anaerobically fermenting solid waste such as concentrated sludge, liquid waste such as human waste, sludge or septic tank sludge, kitchen waste, garbage and livestock excrement. Collect. Then, the methane gas contained in the recovered biogas is used as a fuel to drive the power generation means to supply electric power, or the methane gas is burned to generate steam and supplied to a hot water pool or the like.

First, the garbage and the garbage are put into the crusher 1 and finely crushed, and then put into the mixing tank 2, and the solid waste such as livestock excrement is directly put into the mixing tank 2. Liquid waste such as human waste, sludge or septic tank sludge is dehydrated by a dehydrator 3 provided in the receiving and storage facility to be a concentrated sludge, and then mixed tank 2
Is thrown into. Here, the water removed from the liquid waste is treated by the water treatment facility 4 into colorless and transparent treated water and discharged.

In the mixing tank 2, due to the difference in specific gravity, it is separated into light weight materials such as wood and paper pieces, intermediates such as organic materials and heavy weight materials such as pebbles, glass or metal pieces. Of these, non-fermentable substances other than organic waste such as glass and metal pieces are taken out of the mixing tank 2. Further, before the organic waste to be fermented is put into the fermenter 5, the solid content concentration and the water temperature of the organic waste are adjusted in advance in the mixing tank 2 so that the anaerobic fermentation can be performed rapidly in the fermenter 5. Is set to proceed.

The organic waste introduced into the fermenter 5 is adjusted to a temperature optimum for fermentation by the heating device 8 and is appropriately stirred to proceed anaerobic fermentation to generate biogas. This biogas is guided to the desulfurization tank 10, and a part of the biogas is blown into the fermentation tank 5 by the gas circulation blower 6 to stir the organic waste. The biogas from which the hydrogen sulfide has been removed in the desulfurization tank 10 is stored in the gas holder 7 and is stored in a heat engine such as a gas turbine or a gas engine.
Alternatively, it is supplied to a combustion device such as a boiler and used for power generation or the like.

Next, desulfurization will be described. FIG. 3 is an explanatory diagram showing the desulfurization tank according to the first embodiment. Desulfurization tank 1
Inside 0, a honeycomb-shaped filler 11 in which a plurality of resin cylinders are bundled is provided, and the contact area between methane gas and activated sludge is increased to improve desulfurization efficiency. Since activated sludge is supplied to the filler 11 from the aeration tank 20 (see FIG. 1), if the diameter of the cylinder forming the filler 11 is extremely reduced, the activated sludge may cause clogging. On the other hand, if the diameter of this cylinder is extremely large, the contact area with methane gas cannot be increased. Therefore, it is preferable that the diameter of the cylinder is about 10 mm and the filling height is about 1 m.

The material of the filler 11 is not limited to resin, and porous sintered material, coke or the like may be used. Further, the shape of the filler 11 is not limited to the honeycomb shape as described above, and for example, a plurality of coke lumps having an outer dimension of several tens of mm are collected, or a tubular member having a diameter of 15 to 20 mm and a length of several tens of mm. You may combine several.

At the upper part of the desulfurization tank 10, a spray nozzle 12 for supplying activated sludge to the filler 11 is provided. The spray nozzle 12 is connected to an aeration tank 20 installed in a water treatment facility in the organic waste treatment facility by a pipe 13, and a pump 14 which is a sludge supply means provided in the middle of the pipe 13. The activated sludge in the aeration tank 20 is supplied. The pump 14 is preferably a uniaxial screw pump or a vortex pump. A flow rate adjusting valve 15 is provided in the pipe 13 to control the amount of activated sludge supplied to the spray nozzle 12.

Although not apparent from FIG. 3, a gas supply hole is opened at the bottom of the desulfurization tank 10, and biogas produced in the fermentation tank 5 (see FIG. 2) is supplied from this hole. . In addition, it is desirable to provide a plurality of the gas supply holes over the entire bottom surface of the desulfurization tank 10 as much as possible so that desulfurization is not concentrated in one place. In this case, it is preferable to temporarily store the biogas in the chamber or the like and then supply the biogas to the desulfurization tank 10 because the biogas can be supplied more uniformly.

The desulfurization tank 10 is equipped with a heat exchanger 16 for exchanging the temperature of the fluid flowing from the heating device with the temperature of the air in the desulfurization tank 10. The temperature of the fluid flowing inside the heat exchanger 16 is changed based on the temperature measured by the thermometer 17, so that the inside of the desulfurization tank 10 is maintained at about 30 ° C. Here, general desulfurization bacteria used for biological desulfurization become most active at around 30 ° C,
As the temperature drops, its activity decreases. For example,
When the temperature of the desulfurization bacterium is lowered to 15 ° C, the activity is reduced to about half of the activity at 30 ° C, so that the desulfurization efficiency is reduced accordingly. On the other hand, when the temperature rises, desulfurizing bacteria die. Therefore, by the temperature adjustment device,
The desulfurization tank 10 is always kept at a temperature of about 30 ° C. regardless of the season. The temperature of the desulfurization tank 10 may be adjusted by utilizing the exhaust heat of the biogas power generation system or the like, which will be described later.

Next, the aeration tank will be described with reference to FIG. The aeration tank 20 is provided with an aeration pipe 21 having a hole on its side surface, and the air supplied to the aeration pipe 21 is blown into the activated sludge in the aeration tank 20 through this hole. The air blown into the activated sludge becomes fine bubbles and rises in the activated sludge, and in the process oxygen in the air is dissolved in the activated sludge. Here, the activated sludge means a biological sludge composed of flocs containing many aerobic microorganisms. Activated sludge is used for biological treatment of wastewater because it has excellent ability to adsorb and oxidize organic substances and has extremely high sedimentation property.

As shown in FIG. 3, the activated sludge in the aeration tank 20 in which a large amount of oxygen is dissolved is supplied to the desulfurization tank 10 by the pump 14 which is a sludge supply means, and is prepared in the desulfurization tank 10 by the spray nozzle 12. It is sprinkled on the filled filler 11. FIG. 4 is a perspective view showing the spray nozzle. Figure 4
As shown in (a), the spray nozzle 12 is composed of a tube 12b having a plurality of holes 12a in the axial direction, and can further rotate around the axis of the tube 12b (FIG. 4). (Arrow direction of (a))).

When spraying the activated sludge, the spray nozzle 1
Since the 2 rotates and is sprayed into the desulfurization tank 10, the activated sludge is uniformly sprayed on the filler 11. Therefore, the leakage of biogas supplied from below the filler 11 is reduced, so that the desulfurization can be performed more completely. Note that the spray nozzle is not limited to the one described above, and may be a hose having a diffusion nozzle attached to the tip thereof, for example.

Further, as shown in FIG. 4B, a switching valve 18 may be provided in front of the spraying nozzle 12 to switch between the activated sludge and the cleaning liquid. Then, when the desulfurization tank 10 becomes dirty due to long-term use or when the filling material 11 is clogged, the switching valve 18 may be switched to spray the cleaning liquid from the spray nozzle 12 into the desulfurization tank 10. . By doing so, it is not necessary to separately provide a cleaning nozzle, and since the spray nozzle 12 can be simultaneously cleaned when spraying the cleaning liquid, clogging of the spray nozzle 12 can be avoided. This makes it possible to stably supply activated sludge for a long period of time without the need for maintenance and inspection.

Next, description will be made with reference to FIG. The activated sludge supplied from the spraying nozzle 12 is sprayed on the filler 11 provided in the desulfurization tank 10, and flows downward through the desulfurization tank 10 through the holes of the honeycomb-shaped filler 11. In addition, biogas containing hydrogen sulfide is supplied from a gas supply hole provided at the bottom of the desulfurization tank 1,
0 rise inside. This biogas contacts the activated sludge as it passes through the filler 11. At this time, due to the desulfurization bacteria contained in the activated sludge, an oxidation reaction of H ₂ S + 2O ₂ → H ₂ SO ₄ occurs, and hydrogen sulfide (H _{2 S}
S) and the oxygen (O ₂ ) dissolved in the activated sludge are oxidized to generate sulfuric acid (H ₂ SO ₄ ).

This sulfuric acid dissolves in the activated sludge and is discharged to the outside of the desulfurization tank 10. The biogas after desulfurization has a gas outlet 19 provided above the desulfurization tank 10.
To the outside and stored in a gas holder (not shown). Since the filler 11 through which the activated sludge passes has a honeycomb shape as described above and has a large vertical length, the contact area between the biogas and the activated sludge can be made extremely large. Therefore, the desulfurization efficiency can be increased by using the filler 11.

Here, the activated sludge used for desulfurization in this biological desulfurization device is characterized by a high gas adsorption capacity.
In addition, as described above, activated sludge is flocs containing a large number of aerobic microorganisms, and the density of desulfurizing bacteria and other microorganisms that contribute to desulfurization present therein is extremely higher than that of water. Furthermore, since the activated sludge has a higher viscosity than water, the residence time in the filler 11 is longer than that in water, and the activated sludge can be in contact with the biogas for a longer time. Due to these effects, the desulfurization efficiency can be dramatically increased as compared with the case where a treatment liquid in which water in which microorganisms are dispersed is aerated and oxygen is dissolved is used for desulfurization.

Further, in the conventional biodesulfurization apparatus using the conventional aeration treatment liquid, the microorganisms were collected by the filtration membrane,
In this biodesulfurization device, the microorganisms used for desulfurization are always supplied from activated sludge, so there is no need to recover them with a filtration membrane. Therefore, there is no concern that the filtration membrane will be clogged, and highly reliable operation can be performed. Further, maintenance / inspection and replacement of the filtration membrane are unnecessary, and further, energy for passing the aeration treatment liquid through the filtration membrane is also unnecessary.
Running costs can also be reduced.

Further, in this biodesulfurization apparatus, oxygen and the like are sufficiently dissolved in the sludge by aerating the activated sludge with air or the like. Therefore, it is necessary to supply air and oxygen to the desulfurization tank as in conventional biodesulfurization. There is no. Therefore, the volume of biogas after desulfurization does not increase due to the air or the like supplied to the desulfurization tank, and the size of the gas holder can be reduced. Further, since the concentration of biogas after desulfurization does not become thin due to the air supplied to the desulfurization tank, etc., biogas having a sufficient amount of heat can be obtained.

FIG. 5 is an explanatory view showing an example of a desulfurization tank applicable to this biological desulfurization apparatus. In this way, FIG.
As shown in, the activated sludge may be stored in the desulfurization tank 30, biogas may be supplied from the lower portion of the desulfurization tank, and desulfurization may be performed in the process in which the biogas rises in the activated sludge. This desulfurizer has a simple structure, so maintenance and inspection are easy and the cost is low. Therefore, it is convenient to apply it to a plant having a small desulfurization scale because the maintenance cost can be reduced. However, the contact area between the biogas and the activated sludge cannot be made so large as compared with the desulfurization apparatus, and the contact time cannot be extended, so that the desulfurization efficiency is slightly inferior to the desulfurization apparatus.

Further, as shown in FIG. 5 (b), a plurality of desulfurization tanks 31 containing activated sludge are provided, and the biogas passing through one desulfurization tank 31 is passed to the next desulfurization tank 31 and all of them are sequentially supplied. You may desulfurize by passing through the desulfurization tank 31. By doing this, the contact area and contact time between biogas and activated sludge can be increased with a relatively simple structure,
The desulfurization efficiency can be increased. Alternatively, the inside of the desulfurization tank may be partitioned into a plurality of chambers by a partition plate, the biogas that has passed through one chamber may be passed to the next chamber, and may be sequentially passed through all the chambers for desulfurization.

(Second Embodiment) FIG. 6 is an explanatory view showing a biological desulfurization apparatus according to a second embodiment of the present invention. This biological desulfurization apparatus is characterized in that, in the desulfurization apparatus according to the first embodiment, the activated sludge that has been desulfurized is returned to the aeration tank. As shown in FIG. 6, a drain port 40 is provided in the lower part of the desulfurization tank 10. Then, the pump 50 which is a returning means sucks out the desulfurized activated sludge from the drainage port 40 and returns it to the aeration tank 20.

In this biological desulfurization apparatus, even when there is a portion where the desulfurization is insufficient in the activated sludge, the activated sludge is returned to the aeration tank 20 and aerated, and oxygen is dissolved in the activated sludge. . Therefore, the undesulfurized portion is completely desulfurized by oxygen dissolved in the activated sludge and desulfurizing bacteria and other microorganisms existing in the aeration tank 20. Therefore, hydrogen sulfide in biogas and combustion gas can be almost completely removed. Moreover, in the biological desulfurization apparatus according to the first embodiment, it is necessary to return the desulfurized activated sludge to the water treatment facility again. However, in this biological desulfurization apparatus, since the activated sludge that has been desulfurized is returned to the aeration tank 20 provided in the water treatment facility, the process directly proceeds to the next step of water treatment. Therefore, the step of returning the desulfurized activated sludge to the water treatment facility again becomes unnecessary.

(Embodiment 3) FIG. 7 is an explanatory view showing a biogas power generator according to Embodiment 3 of the present invention. This biogas power generation device is characterized in that biogas desulfurized by a biodesulfurization device using activated sludge is used as a fuel for power generation, and exhaust heat discharged during power generation is used for temperature control of a desulfurization tank. The biogas generator 60 is
Biogas is produced by anaerobic fermentation of organic waste. The biogas is desulfurized in the desulfurization tank 10 and then stored in the gas holder 7. The biological desulfurization apparatus described in the first or second embodiment can be applied to the biological desulfurization, but in the following description, the second embodiment of the present invention will be described.
The biological desulfurization equipment pertaining to

In this biogas power generator, the biodesulfurizer according to the second embodiment (see FIG. 6) is used, so the size of the gas holder 7 can be relatively small. Therefore, the space of the power generation facility can be effectively used. Also,
Combustion components such as methane gas contained in the desulfurized biogas are almost constant because no excess air is supplied, and a sufficient amount of heat is generated during combustion, so that electric power can be efficiently supplied. The biogas is stored in the gas holder 7 and then supplied to the gas engine 70 to drive it, if necessary. Then, electric power is generated by a generator 72 that is a power generation means connected to the gas engine 70.

Since the exhaust gas of the gas engine 70 has a high temperature, the exhaust gas is guided to the exhaust heat recovery boiler 74 to generate steam and hot water. These steam and hot water are stored in the steam header 76 and the hot water header 78, and then used for heating a building or a hot water pool as needed. By the way, when the temperature is low such as in winter, the temperature in the desulfurization tank 10 is also low, so that the activity of the desulfurizing bacteria may be reduced, and as a result, the desulfurization efficiency may be reduced. Therefore, the temperature in the desulfurization tank 10 is maintained at about 30 ° C. where the activity of the desulfurizing bacteria becomes active by the following temperature adjusting means.

This temperature adjusting means causes hot water generated in the exhaust heat recovery boiler to flow through the piping of the heat exchanger 16 which is the temperature adjusting means provided in the desulfurization tank 10 to warm the inside of the desulfurization tank 10 and The temperature is kept at about 30 ° C. At this time, the heat exchanger 1 is controlled by a flow rate adjusting means such as a valve.
The temperature in the desulfurization tank 10 can be changed by adjusting the amount of hot water flowing in 6. Instead of the heat exchanger 16, a pipe may be attached to the wall surface of the desulfurization tank 10 and hot water may be flown through the pipe.

Further, a part of the steam stored in the steam header 76 is supplied to the absorption refrigerator 80, and is used for cooling refrigeration equipment or a building or for producing cold water. When the temperature is high, such as in summer, the temperature in the desulfurization tank 10 may exceed 30 ° C. In such a case, the activity of the desulfurization bacterium may be slowed or the desulfurization bacterium may die, and the desulfurization efficiency may be reduced. In such a case valve 8
2 is switched to allow the cold water generated by the absorption refrigerator 80 to flow into the heat exchanger 16 provided in the desulfurization tank 10. Then, the temperature in the desulfurization tank 10 can be maintained at about 30 ° C., and the activity of desulfurizing bacteria can be activated to maintain high desulfurization efficiency. The temperature in the desulfurization tank 10 can be changed by adjusting the amount of cold water flowing through the heat exchanger 16 with a flow rate adjusting device such as a valve. In the summer, the temperature inside the desulfurization tank 10 can be maintained at about 30 ° C. by such temperature adjusting means.

A gas turbine may be used instead of the gas engine 70. Alternatively, biogas may be combusted in a combustor, the heat may be used to operate a boiler to generate steam, and the steam may be used as it is for heating a building or the like. Further, this vapor may be supplied to the absorption refrigerator 80 to operate the refrigeration equipment or be used for cooling a building or the like. Further, hydrogen may be separated from methane gas in the biogas and supplied to the fuel cell, thereby supplying electric power. Then, the desulfurization tank 10 is utilized by utilizing the exhaust heat of the fuel cell.
It is also possible to adjust the temperature of the air conditioner and to control the air conditioner of a building. Especially when a fuel cell is used, the power generation efficiency is higher than when a gas engine or gas turbine is used, so that biogas can be used efficiently.

[0053]

As described above, in the biological desulfurization apparatus according to the present invention (Claim 1), activated sludge having a high microbial density is supplied from the aeration tank to the desulfurization tank, and the gas containing sulfide is passed through it. And desulfurized. Since the activated sludge having a high microbial density and oxygen dissolved by aeration is used for desulfurization, desulfurization can be efficiently performed. Also,
Since it is not necessary to perform membrane filtration on the waste water after desulfurization as in the conventional case, the reliability of the entire apparatus can be increased.

In the biological desulfurization apparatus according to the present invention (claim 2), the desulfurized activated sludge is returned to the aeration tank in the biological desulfurization apparatus. For this reason, the undesulfurized component remaining in the activated sludge becomes fully dissolved in oxygen by being aerated again in the aeration tank, so that the undesulfurized component can be desulfurized by this oxygen. In addition, since the microorganisms in the aeration tank can also be used for desulfurization, almost no undesulfurized content exists. Therefore, most harmful hydrogen sulfide in the gas can be removed, and the environmental load can be reduced.

In the biogas power generator according to the present invention (claim 3), biogas generated by anaerobic fermentation of organic waste is passed through activated sludge supplied from an aeration tank to be desulfurized, With this, the power generation means is operated to supply electric power. For this reason, in the desulfurization of biogas unlike the conventional case, it is not necessary to supply air or the like in the desulfurization tank, and therefore the volume of the biogas after desulfurization hardly increases. For this reason, the gas holder for storing the gas after desulfurization can be made small, so that the entire power generation device can be made compact. Moreover, since the components of biogas after desulfurization hardly change, they can be used as a high-quality fuel with many active components in a power generation means, and electric power can be efficiently supplied.

Further, in the biogas power generation device according to the present invention (claim 4),
Further, the temperature adjusting means for adjusting the temperature in the desulfurization tank by the exhaust heat of the power generating means is provided. Desulfurization bacteria grow at around 30 ° C, their growth activity declines when the temperature becomes low, and they die when the temperature is too high.
The exhaust heat of the power generation means can be used to control the temperature of the desulfurization tank so that the temperature in the desulfurization tank can be maintained at around 30 ° C. For this reason,
The active growth activity of desulfurization bacteria can increase the desulfurization efficiency and enable stable desulfurization throughout the year. In addition, since the exhaust heat generated as a result of using biogas for power generation is used for adjusting the temperature of the desulfurization tank, the thermal efficiency of the entire system can be increased.

In the biological desulfurization method according to the present invention (claim 5), activated sludge from the aeration tank is supplied to the desulfurization tank,
A gas containing a sulfide was passed through this activated sludge for desulfurization. As described above, since the activated sludge having a high microbial density is used and the activated sludge is sufficiently dissolved in oxygen by aeration, the desulfurization efficiency can be increased. Further, unlike the conventional biological desulfurization method, it is not necessary to perform membrane filtration on the waste water after desulfurization, so that maintenance and inspection work is not required. In addition, since activated sludge may be carried from a human waste treatment facility or livestock excrement treatment facility by a tank car and supplied to a desulfurization tank, a desulfurization tank exists independently in a power plant, etc. Effective biodesulfurization can be performed even when the treatment facility is not near the power plant.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a biological desulfurization device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a biogas generator.

FIG. 3 is an explanatory diagram showing a desulfurization tank according to the first embodiment.

FIG. 4 is a perspective view showing a spray nozzle.

FIG. 5 is an explanatory diagram showing an example of a desulfurization tank applicable to this biological desulfurization apparatus.

FIG. 6 is an explanatory diagram showing a biological desulfurization apparatus according to Embodiment 2 of the present invention.

FIG. 7 is an explanatory diagram showing a biogas power generator according to Embodiment 3 of the present invention.

FIG. 8 is an explanatory diagram showing a conventional biological desulfurization tower.

[Explanation of symbols] 1 crusher 2 mixing tanks 3 dehydrator 4 Water treatment equipment 5 fermenters 6 gas circulation blower 7 gas holder 8 heating device 10 Desulfurization tank 11 Filling material 12 spray nozzles 12a hole 12b tube 13 Piping 14,50 pumps 15 Flow control valve 16 heat exchanger 17 Thermometer 18 Switching valve 19 Gas outlet 20 Aeration tank 21 Aeration pipe 30, 31 desulfurization tank 40 drain 60 Biogas generator 70 gas engine 72 generator 74 Exhaust heat recovery boiler 76 steam header 78 Hot water header 80 absorption refrigerator 82 valve 100 biological desulfurization tower 101 Filler layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C02F 11/04 F term (reference) 4D002 AA03 AC10 BA17 CA01 CA06 CA07 DA59 EA05 HA08 4D020 AA04 BA22 BB05 CB01 CB09 4D028 BC28 BD11 BE00 4D059 AA01 AA02 AA03 AA07 BA01 BA15 BA21 CA21 EB06

Claims (5)

[Claims] 1. An aeration tank used for biological treatment of human waste, septic tank sludge, sewage sludge and other organic wastes by the activated sludge method, and activated sludge supplied from the aeration tank to which sulfide is added. A biodesulfurization apparatus, comprising: a desulfurization tank for removing the sulfide by a biodesulfurization action by passing a gas containing 2. The biodesulfurization apparatus according to claim 1, further comprising return means for returning the desulfurized activated sludge supplied to the desulfurization tank to the aeration tank. 3. A gas generator for anaerobically fermenting organic waste to generate biogas, and used for biological treatment of human waste, septic tank sludge, sewage sludge and other organic waste by the activated sludge method. An aeration tank, a desulfurization tank that allows a gas containing sulfide to pass through and removes the sulfide by a biodesulfurization action, and a sludge supply unit that supplies activated sludge containing oxygen dissolved by aeration from the aeration tank to the desulfurization tank. The activated sludge supplied to the desulfurization tank, a gas supply means for supplying the biogas, a returning means for returning the desulfurized activated sludge supplied to the desulfurization tank to the aeration tank, and after desulfurization A biogas power generation device comprising: a power generation unit that generates electric power using biogas as a fuel. 4. The biogas power generator according to claim 3, further comprising temperature adjusting means for adjusting the temperature in the desulfurization tank by the exhaust heat of the heat engine. 5. A step of aerating biological treatment of human waste, septic tank sludge, sewage sludge and other organic wastes by an activated sludge method, and supplying activated sludge containing oxygen dissolved therein to a desulfurization tank by the aeration step, A biodesulfurization method comprising a step of removing a sulfide by a biodesulfurization action by allowing a gas containing sulfide to pass through the activated sludge.