JP2012255155A - Biological desulfurization apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biological desulfurization apparatus which can be started up by adhesion of sulfur-oxidizing bacteria to a carrier-packed layer under circulation of microorganism-containing liquid or sludge and can judge the timing of stopping the circulation of microorganism-containing liquid or sludge to switch into water sprinkling; and to provide a method of starting up the same.SOLUTION: The biological desulfurization apparatus includes: a biological reaction tank 1 into which a hydrogen sulfide gas-containing gas is introduced; carrier-packed layers 2a and 2b that are arranged in the biological reaction tank 1 and packed with a carrier for adhesion of microorganisms; a means 14 that feeds an oxygen-containing gas to the biological reaction tank 1; two or more sprinkling mechanisms 3 and 4 that sprinkle water necessary for the organisms onto the upper part of the biological reaction tank 1; and at least two detectors of a detector 21 for measuring the pH or alkali level of discharged water discharged from a biological reaction tank 1, a detector 23 for detecting the white turbidity of a microorganism-containing liquid or sludge in a circulation tank 5, and a hydrogen sulfide concentration detector 22 for measuring the concentration of hydrogen sulfide in a treated-gas pipe 13 of a biological reaction tank 1.

Description

  The present invention particularly relates to a biodesulfurization apparatus for biogas generated by anaerobic digestion treatment of organic wastewater such as sewage and industrial wastewater.

  As a method for treating organic waste such as sewage sludge and garbage and organic waste water such as food factory effluent, the methane fermentation treatment method has been widely applied. This methane fermentation treatment method introduces organic waste or organic wastewater into a biological reaction tank, decomposes the organic matter with the methane-fermenting bacteria group filled in the biological reaction tank, and generates biogas mainly composed of methane gas. In addition, it is a treatment method that decomposes and removes organic substances in the wastewater. However, when the sulfur component such as protein is contained in the waste water, the sulfur component is reduced by the action of sulfate reducing bacteria, and hydrogen sulfide gas is generated in the biogas.

  When methane gas contained in biogas is used as fuel for boilers or generators, it is necessary to remove hydrogen sulfide gas contained in biogas. The reason for this is that when the biogas is burned, the hydrogen sulfide gas in the biogas is oxidized to produce sulfur oxides, which may corrode the equipment.

  As a method for removing hydrogen sulfide gas contained in biogas, there are a dry desulfurization method in which adsorption is performed using an adsorbent mainly composed of iron oxide, and a wet desulfurization method in which an aqueous solution using an alkali is absorbed and removed. It's being used. In these methods, a chemical such as an adsorbent is necessary for the adsorption, and the adsorbent after the adsorption becomes a waste, so that the running cost is increased.

  Therefore, the present inventors, as a system for performing desulfurization at a low running cost, previously filled a reaction tank with a filler to which microorganisms that oxidize and decompose hydrogen sulfide are attached, and removes hydrogen sulfide in biogas. Has proposed. In this method, treated water that has been subjected to aerobic treatment is poured from the top into a biological reaction tank filled with a filler to which microorganisms have adhered, while supplying water and alkalinity necessary for microorganisms, It is an apparatus that introduces gas and air, oxidizes and removes hydrogen sulfide in the gas, and performs processing.

Japanese Patent Application No. 2007-20018

In the invention, a gas containing hydrogen sulfide gas is introduced, a biological reaction tank filled with a filler for adhering microorganisms, a means for supplying a gas containing oxygen into the biological reaction tank, and an organism at the top of the biological reaction tank. This is a biological desulfurization apparatus having watering means for spraying necessary water (for example, treated water after biological treatment). However, in starting up, there were the following problems.
(1) Without rapid start-up of the biological desulfurization device, biogas cannot be effectively used by boilers and generators due to corrosion problems caused by the concentration of hydrogen sulfide in the gas.
(2) It is difficult to achieve both rapid startup and stable processing after startup.
(3) The watering device is clogged.

  In solving the above problem, a sulfur-oxidizing bacterium that oxidizes sulfur is attached to the filler, and it is determined by some index whether or not the amount of attachment is sufficient to achieve the target hydrogen sulfide removal. It is necessary.

  The present invention has been made in order to solve the above-described problems. While circulating a liquid or sludge containing microorganisms, it is started by attaching sulfur-oxidizing bacteria to the carrier packed bed, and circulation of the liquid or sludge containing microorganisms is performed. An object of the present invention is to provide a biological desulfurization apparatus that can determine the timing of stopping and switching to watering.

  The biological desulfurization apparatus of the present invention includes a biological reaction tank into which a gas containing hydrogen sulfide gas is introduced, a carrier-packed layer disposed in the biological reaction tank and filled with a carrier for attaching microorganisms, and the biological A means for supplying a gas containing oxygen into the reaction tank and two or more types of watering mechanisms for spraying water necessary for the living organisms are provided in the upper part of the biological reaction tank.

  The biological desulfurization apparatus start-up method of the present invention is the above-described biodesulfurization apparatus start-up method, in which a microorganism-containing liquid or sludge is introduced as a biological desulfurization seed sludge and circulated to a biological reaction tank and a circulation tank. A first watering mechanism having a pump and piping is provided, and in this first watering mechanism, the piping connecting the circulation tank and the biological reaction tank extends to the inside of the biological reaction tank, and the extended piping portion Has a hole having a diameter of 5 to 20 mm, and has a second watering mechanism provided with a pipe for sprinkling water into the carrier packed bed in the upper part of the biological reaction tank. This pipe is extended to the inside of the biological reaction tank, and a nozzle with good dispersibility is provided in the extended pipe part, and gas containing hydrogen sulfide and gas containing oxygen are circulated while circulating liquid or sludge containing microorganisms. Supply to the biological reaction tank The and performs the launch of the biological desulfurization device while attached to the carrier.

Explanatory drawing of the biological desulfurization apparatus which concerns on Example 1 of this invention. The schematic whole figure of the biological desulfurization apparatus which concerns on Example 2 of this invention. FIG. 5 is a schematic overall view of a biological desulfurization apparatus according to Embodiment 3 of the present invention. FIG. 6 is a schematic overall view of a biological desulfurization apparatus according to Embodiment 4 of the present invention. FIG. 6 is a schematic overall view of a biological desulfurization apparatus according to Embodiment 5 of the present invention.

Hereinafter, the biological desulfurization apparatus according to the present invention will be described in more detail.
(1) As described above, the biological desulfurization apparatus of the present invention includes a biological reaction tank, a carrier packed bed, a means for supplying a gas containing oxygen into the biological reaction tank, and two or more types of watering mechanisms. is doing. Here, the watering mechanism is a biological reaction of the first watering mechanism and water with low solid content (biologically treated water) in order to circulate the microorganism-containing liquid or sludge as biological desulfurization seed sludge and circulate it in the biological reaction tank A second watering mechanism for spraying onto the carrier packed bed in the tank is provided. Here, the first watering mechanism includes, for example, a circulation tank for introducing a liquid or sludge containing microorganisms as seed sludge for biological desulfurization and circulating it to the biological reaction tank, a circulation pump, and a pipe (circulation) for connecting them. Piping).

  (2) In the start-up method of the biological desulfurization apparatus of the present invention, as described above, in the first watering mechanism, the circulation pipe extends to the inside of the biological reaction tank, and the extended pipe portion has a diameter of 5 A liquid containing a microorganism having a hole with a size of ˜20 mm, the piping of the second watering mechanism extending to the inside of the biological reaction tank, and a nozzle having good dispersibility is provided in the extending piping portion. Alternatively, a gas containing hydrogen sulfide and a gas containing oxygen are supplied into the biological reaction tank while circulating the sludge, and the biological desulfurization apparatus is started up while attaching microorganisms to the carrier.

  Here, the following method is mentioned as a method of switching the watering to the upper part of a biological reaction tank. (2-1) Measure the pH or alkalinity of the waste water from the biological reaction tank, and if either or both of the pH and alkalinity of the waste water from the biological reaction tank drop, contain microorganisms To stop the circulation of liquid or sludge to be used and switch to watering to the top of the biological reaction tank. (2-2) Measure the hydrogen sulfide gas concentration in the outlet gas of the biological reaction tank. When the hydrogen sulfide concentration in the outlet gas decreases, stop the circulation of the liquid or sludge containing microorganisms, and To switch to watering.

(2-3) Method of detecting water turbidity in the circulation tank, and when the turbidity in the circulation tank is confirmed, stop the circulation of the liquid or sludge containing microorganisms and switch to watering to the top of the biological reaction tank .
(2-4) By using two or more methods described in (2-1) to (2-3) above, the circulation of liquid or sludge containing microorganisms is stopped, and water is sprayed onto the upper part of the biological reaction tank. A method of determining the timing of switching and switching.
Moreover, in this invention, the digestive liquid of the facility which is performing the anaerobic digestion process, or digested sludge can be utilized as said seed sludge.

Next, a specific example of the biological desulfurization apparatus according to the embodiment of the present invention will be described with reference to the drawings. Note that the present embodiment is not limited to the following description.
(Example 1): Corresponding to claims 1 and 2
A biological desulfurization apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 (A) and 1 (B). Here, FIG. 1 (A) is a schematic overall view of the biodesulfurization apparatus, and FIG. 1 (B) is a bottom view of the piping of the first watering mechanism of FIG. 1 (A).
Reference numeral 1 in the figure denotes a biological reaction tank into which a gas containing hydrogen sulfide gas is introduced. Inside the biological reaction tank 1, carrier packed layers 2a and 2b filled with a carrier for attaching microorganisms are arranged vertically. A gas containing hydrogen sulfide and air are supplied into the biological reaction tank 1 from the bottom. A first watering mechanism 3 and a second watering mechanism 4 for sprinkling water necessary for living organisms are arranged in the upper part of the biological reaction tank 1 and in the vicinity thereof.

  The first watering mechanism 3 is for introducing a liquid or sludge containing microorganisms into the biological reaction tank 1 as a seed sludge for biological desulfurization and circulating it. The circulation tank 5, the circulation pump 6, and the circulation tank 5 and a circulation pipe 7 for connecting the biological reaction tank 1 to each other. In this first watering mechanism 3, the circulation pipe 7 extends to the inside of the biological reaction tank 1, and a plurality of holes 8 having a diameter of 5 to 20 mm are opened in the extended pipe portion. (See FIG. 1A). The hole 8 is for spraying a liquid or sludge containing microorganisms onto the carrier packed layers 2a and 2b, and is set larger than the diameter of a shower nozzle described later. A valve 9 a is interposed in the middle of the circulation pipe 7.

  The 2nd watering mechanism 4 is provided with the piping 10 extended to the inside of a biological reaction tank, and the shower nozzle 11 with good dispersibility is provided in the front-end | tip part of the extended piping. A valve 9 b is interposed in the pipe 10. From the shower nozzle 11 of the pipe 10, water with a small solid content (for example, treated water after the wastewater is biologically treated, hereinafter referred to as biologically treated water) is sprayed onto the carrier packed layers 2 a and 2 b. In the figure, reference numeral 12 denotes a drain pipe, reference numeral 13 denotes a processing gas pipe, and reference numeral 14 denotes an air supply pipe for supplying air to the biological reaction tank 1 (means for supplying a gas containing oxygen).

  As shown in FIG. 1, the biological desulfurization apparatus according to the first embodiment is filled with a biological reaction tank 1 into which a gas containing hydrogen sulfide gas is introduced and a carrier that is disposed in the biological reaction tank and adheres microorganisms. Carrier packed layers 2a and 2b, means for supplying gas containing oxygen into the biological reaction tank, first watering mechanism 3 for introducing a liquid or sludge containing microorganisms into the upper part of the biological reaction tank, A second watering mechanism 4 for spraying biologically treated water is provided in the upper part of the reaction tank.

  When the biological desulfurization apparatus having such a configuration is started, a liquid or sludge containing microorganisms is used by using the circulation tank 5, the circulation pump 6, and the circulation pipe 7 in a state where a liquid or sludge containing microorganisms is charged into the circulation tank 5. The gas containing hydrogen sulfide and air are supplied into the biological reaction tank while the microorganisms are circulated and supplied to the biological reaction tank 1, and the microorganisms are attached to the carriers in the carrier packed layers 2a and 2b. By such start-up, sulfur-oxidizing bacteria are attached to the packed layers 2a and 2b, and the sulfur-oxidizing bacteria attached to the packed layers 2a and 2b are proliferated using them as seed bacteria.

  In FIG. 1, if a thing containing a large amount of solid content such as digested sludge is circulated through the same pipe as the shower nozzle for sprinkling biologically treated water, the shower nozzle may be clogged by the solid content. In addition, even if the stock solution to be circulated is a liquid with a small solid content, when sulfur sulfide in the gas is oxidized by the action of sulfur-oxidizing bacteria, simple sulfur, which is partly solid, is produced. This can cause clogging of the shower nozzle.

  However, in the first embodiment, the clogging of the shower nozzle 11 can be eliminated by making the piping 10 for sprinkling water and the circulation piping 7 used when the biological desulfurization apparatus is started up as separate lines. In addition, the sprinkling of the biologically treated water can efficiently proceed with the dissolution reaction and biological reaction of hydrogen sulfide gas into the liquid in the carrier packed bed by dispersing the liquid with the shower nozzle 11.

  In Example 1, the liquid or sludge containing microorganisms only needs to contain sulfur-oxidizing bacteria, and may be anything that lives in an environment containing hydrogen sulfide, a trace amount of oxygen, and water. Specifically, it may be a treatment liquid of a biological desulfurization apparatus operating elsewhere, a digestion liquid of anaerobic digestion treatment, digested sludge, or the like. According to the present inventor, if a part of the surface is exposed to oxygen in digested liquid or digested sludge, sulfur-oxidizing bacteria exist, and it is possible to start up a biological desulfurization apparatus in a short period of time. Has been confirmed.

(Example 2): Corresponding to claims 1 and 3
A biological desulfurization apparatus according to Embodiment 2 of the present invention will be described with reference to FIG. However, the same members as those in FIG. 1 are denoted by the same reference numerals and the description thereof will be omitted, and only the main parts will be described.
The second embodiment is characterized in that the drain pipe 12 is provided with a pH meter 21 for measuring the pH of the waste water discharged from the biological reaction tank 1. In addition, you may arrange | position the measuring meter which measures alkalinity instead of the pH measuring meter which measures pH.

By introducing liquid or sludge containing microorganisms into the circulation tank 5 and starting up while circulating the liquid or sludge while ventilating a gas containing hydrogen sulfide gas and a gas containing oxygen (air), sulphur-oxidizing bacteria are sufficient. If it adheres to the packed bed, it is oxidized to hydrogen sulfide simple substance sulfur (SO) in the gas, and part is oxidized to sulfuric acid.
As the sulfuric acid concentration increases, the pH and alkalinity in the wastewater will eventually decrease. Stop the circulation of water or sludge containing microorganisms at the timing when pH and alkalinity are reduced, and switch to watering of biologically treated water.

  By the way, a decrease in pH and alkalinity mainly caused by sulfuric acid is not preferable because it causes corrosion of piping of the biological desulfurization facility and the casing of the biological reaction tank 1. On the other hand, the decrease in pH and alkalinity is an index indicating that sulfur-oxidizing bacteria are sufficiently attached to the carrier packed layers 2a and 2b.

  According to the second embodiment, by providing a pH meter 21 in the drain pipe 12, when the pH and alkalinity are lower than predetermined values, switching to the sprinkling of biologically treated water prevents the corrosion and at the same time The desulfurization apparatus can be started up quickly, and stable treatment can be realized even after startup.

  In fact, in a test conducted by the present inventors, a gas containing 10000 ppm of hydrogen sulfide gas was ventilated while circulating a digestion solution containing an alkalinity of about 4000 mg / L. / L, and a sudden drop in pH (from about 7 to 2 to 3) was observed. From these facts, it is considered that the determination value for reduction should be switched when the alkalinity is 1000 mg / L or less and the pH is 6 or less.

(Example 3): Corresponding to claims 1 and 4
A biological desulfurization apparatus according to Embodiment 3 of the present invention will be described with reference to FIG. However, the same members as those in FIG. 1 are denoted by the same reference numerals and the description thereof will be omitted, and only the main parts will be described.
The third embodiment is characterized in that a hydrogen sulfide concentration detector 22 for measuring the hydrogen sulfide concentration is provided in the processing gas pipe 13 from the biological reaction tank 1.

By putting the liquid or sludge containing microorganisms into the circulation tank 5 and circulating the liquid or sludge, a gas containing hydrogen sulfide gas and a gas containing oxygen are vented and started up. If attached, a part of hydrogen sulfide in the gas is oxidized to elemental sulfur (S ₀ ) and a part is oxidized to sulfuric acid.
Along with this, hydrogen sulfide in the gas is desulfurized, and the concentration of hydrogen sulfide in the processing gas decreases. When the hydrogen sulfide concentration in the treatment gas sufficiently satisfies the target removal performance, it can be considered that sufficient organisms are attached to the carrier, and at that timing, the circulation of water or sludge containing microorganisms is stopped, Switch to watering of biologically treated water.

According to the third embodiment, by providing the hydrogen sulfide concentration detector 22 in the processing gas pipe 13, the biological desulfurization device is determined by determining the timing for switching the water sprayed on the biological treatment water based on the hydrogen sulfide concentration in the processing gas. It is possible to start up quickly and stabilize the processing.
In fact, in a test conducted by the present inventors, a gas containing 10000 ppm of hydrogen sulfide gas was ventilated while circulating a digestive liquid containing an alkalinity of about 4000 mg / L. However, after 2 to 4 days, it dropped to near zero.

(Example 4): Corresponding to claims 1 and 5
A biological desulfurization apparatus according to Embodiment 4 of the present invention will be described with reference to FIG. However, the same members as those in FIG. 1 are denoted by the same reference numerals and the description thereof will be omitted, and only the main parts will be described.
The fifth embodiment is characterized in that the circulation tank 5 is provided with a detector 23 for detecting white turbidity of the liquid or sludge containing microorganisms in the circulation tank 5. Here, when a camera is used, the chromaticity of sludge or liquid is determined by image analysis.

By putting liquid or sludge containing microorganisms into the circulation tank and circulating the liquid or sludge, a gas containing hydrogen sulfide gas and a gas containing oxygen are vented and started up, so that sulfur-oxidizing bacteria adhere to the carrier sufficiently. Then, a part of hydrogen sulfide in the gas is oxidized to elemental sulfur (S ₀ ) and a part is oxidized to sulfuric acid. The circulating fluid becomes cloudy due to the increase of elemental sulfur. This white turbidity is detected by a detector 23 provided in the circulation tank 5, and when the white turbidity becomes equal to or higher than a determination value, the circulation of water or sludge containing microorganisms is stopped and switched to watering of biologically treated water.

  According to the fourth embodiment, by providing the detector 23 in the circulation tank 5, the cloudiness of the liquid or sludge containing microorganisms in the circulation tank 5 is detected, and an increase in the generation of simple sulfur is determined. By detecting the switching timing of the sprinkling of the biologically treated water based on the detection of the white turbidity, the biological desulfurization apparatus can be quickly started up and the treatment can be stabilized.

  In Example 4, as a method of detecting white turbidity, in addition to the above-described detector, for example, visual observation, sampling a part of water in the circulation tank, and visualizing the color of the sampled solid content Or the method of determining by image analysis etc. can be considered.

Example 5: Corresponding to claims 1 and 6
A biological desulfurization apparatus according to Embodiment 5 of the present invention will be described with reference to FIG. However, the same members as those shown in FIGS.
The fifth embodiment is characterized in that a pH meter 21 is provided in the drain pipe 12, a hydrogen sulfide concentration detector 22 is provided in the processing gas pipe 13, and a detector 23 is further provided in the circulation tank 5.

By putting the liquid or sludge containing microorganisms into the circulation tank 5 and circulating the liquid or sludge, a gas containing hydrogen sulfide gas and a gas containing oxygen are vented and started up. If attached, a part of hydrogen sulfide in the gas is oxidized to elemental sulfur (S ₀ ) and a part is oxidized to sulfuric acid. Along with this, an increase in elemental sulfur, a decrease in hydrogen sulfide concentration in the processing gas, and a decrease in pH and alkalinity associated with an increase in sulfuric acid are observed.

  According to Example 5, the pH of the mud or liquid discharged by the pH meter 21, the hydrogen sulfide concentration in the process gas by the hydrogen sulfide concentration detector 22, and the degree of white turbidity of the liquid or sludge by the detector 23. By detecting each, it is possible to make a more accurate determination by determining switching to watering of biologically treated water using a plurality of items.

  In addition, in Example 5, although the case where the water sprinkling of biologically treated water was switched with pH, hydrogen sulfide concentration, and white turbidity was described, it is not limited to this, and two or more such as pH and hydrogen sulfide concentration are used. You may judge the switching of watering by a plurality of items.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment. Specifically, as the above-mentioned seed sludge, a digested liquid or a digested sludge of a facility that performs anaerobic digestion treatment may be used.

  DESCRIPTION OF SYMBOLS 1 ... Biological reaction tank, 2a, 2b ... Carrier packed bed, 3 ... 1st air diffusion mechanism, 4 ... 2nd air diffusion mechanism, 5 ... Circulation tank, 6 ... Circulation pump, 7 ... Circulation piping, 8 ... Hole , 9a, 9b ... valves, 10 ... piping, 11 ... shower nozzle, 12 ... drain pipe, 13 ... treatment gas piping, 21 ... pH meter, 22 ... hydrogen sulfide concentration meter, 23 ... cloudiness detector.

Claims (2)

A bioreactor into which a gas containing hydrogen sulfide gas is introduced; a carrier-filled layer disposed in the bioreactor and filled with a carrier for adhering microorganisms; and a gas containing oxygen in the bioreactor A means for supplying water, and two or more types of watering mechanisms for sprinkling water necessary for living organisms in the upper part of the biological reaction tank,
Detector for measuring pH or alkalinity of waste water from the biological reaction tank, detection for detecting the degree of white turbidity of a liquid or sludge containing microorganisms in a circulation tank which is one component of one of the watering mechanisms A biodesulfurization apparatus comprising: a meter, and at least two of a hydrogen sulfide concentration detector for measuring a hydrogen sulfide concentration in an outlet gas of the biological reaction tank.   The biodesulfurization apparatus according to claim 1, comprising all three types of detectors among the detectors.

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