KR100973786B1 - Anaerobic digestion method of organic waste having high salinity - Google Patents

Abstract

PURPOSE: An anaerobic digestion method of organic waste having high salinity is provided to obtain sludge for compost having low density of salt by preparing an environment where an anaerobic digester is continuously survive. CONSTITUTION: An anaerobic digestion method of organic waste having high salinity comprises the steps of: injecting digested sludge into a solid/liquid separation tube(120), wherein the digested sludge is created in an anaerobic digester(110) into which an organic waste is injected; separating the digested sludge from the high liquid separation tube; re-injecting the transfer sludge obtained from the high liquid separation tube into the anaerobic digester; discharging the solid sludge to the outside when the density of salt is lowered into a certain level; and discharging the waste separated from the high liquid separation tube to an additional processing facility after judging whether or not the residual sludge can be used as the compost.

Description

Anaerobic Digestion Method of Organic Wastes with High Salt Content {ANAEROBIC DIGESTION METHOD OF ORGANIC WASTE HAVING HIGH SALINITY}

The present invention relates to an anaerobic digestion method of organic waste having a high salt content, and more particularly, to produce a biogas while lowering the salt concentration in the anaerobic digester to create an environment in which anaerobic microorganisms can continuously survive, and A method of anaerobic digestion of organic wastes capable of producing low concentration sludge.

Wherever humans live, organic waste is produced.

In general, the organic waste is used to collectively mean various kinds of food waste, livestock manure, sewage concentrate sludge, crop waste, slaughterhouse waste, and the like.

When the organic waste is buried in the soil, methane and carbon dioxide, which cause global warming, are generated, and when it is thrown into the sea, it pollutes the ocean.

Therefore, organic waste is inclined to prohibit landfilling in the world, and Korea has also banned landfilling of food waste since 2005.

The London Protocol also prohibits ocean dumping of organic waste from 2013 onwards. Accordingly, organic waste that pollutes the earth should be sought to be treated on the ground in any form.

It is difficult to treat food waste, pig manure, etc. which contain much salt among the said organic wastes by the existing treatment system.

In particular, food waste in our country contains a lot of salt, so it is difficult to dispose of food waste.

As a method of treating organic wastes containing a lot of salts, a method of separating organic wastes into solids and liquids (hereinafter referred to as 'solid-liquid separation') and using the solid sludge obtained at this time as feed or compost are known.

However, the use of salt-rich compost not only harms the soil, but also damages the growth of crops.

Therefore, the solid sludge containing a lot of salt should be used as a compost after the treatment to reduce the salt concentration.

One of the methods of treating organic waste is the digestion using anaerobic microorganisms. This method is advantageous in that biogas can be produced during the treatment, waste can be disposed of sanitarily, and odor can be suppressed.

However, when an organic waste having a high salt content is digested using anaerobic microorganisms, the microbial cell membrane and cell wall are destroyed by the salts contained in the organic waste, and the microorganism cannot live.

Accordingly, the salt concentration of the organic waste should be lowered, and water is usually added to lower the salt concentration.

In other words, before the treatment of the organic waste, separate water is added and then the organic waste is decomposed in the fermenter. These wet methods can be divided into one-stage wet method and two-stage wet method.

First, the one-stage wet method is a method in which the organic waste added with water is fermented while stirring in one fermenter. This method has the advantage that the process is simple, but since the waste having different reaction optimum conditions is decomposed in one fermenter, the degradation efficiency is lowered and the processing time is long, such as 10 to 25 days.

As a solution to this problem, there is a two-stage wet method using two fermenters to use the optimum conditions for each reaction step of anaerobic digestion.

In the two-stage wet method, the fermentation tank in which the hydrolysis and acid production reaction take place and the fermentation tank in which the methane production reaction occurs are separated from each other. The two-stage wet method has the advantage that the residence time in the fermenter is short as several days due to its excellent decomposition efficiency, but it requires a large amount of water.

In other words, in order to digest using anaerobic microorganisms by the two-stage wet method, the concentration of salts should be reduced by setting the ratio of organic waste to water to be 1: 1 or 1: 3 or more.

For example, 100 tonnes or 300 tonnes of water are required to treat 100 tonnes of organic waste. In order to supply such a huge amount of water, additional large facilities are needed. In addition, there is a problem that it is difficult to control this, it is difficult to actually operate the treatment facility.

In addition, the use of a large amount of water increases the amount of wastewater generated during the treatment. For example, in the process of processing 100 tons of organic waste, more than 200 or 400 tons of waste water are generated. Thus, there is a further need for a facility for treating such a large amount of wastewater again.

As a result, according to the conventional treatment method, a large amount of water is required to lower the salt concentration in order to use the anaerobic microorganisms, and if the water is not added, the anaerobic microorganisms are difficult to continuously survive, thereby reducing the treatment efficiency. However, the high salt content of solid sludge has a problem that can not be used immediately as compost.

The present invention has been proposed to solve the above-mentioned conventional problems, and when the organic waste such as food waste, sewage sludge, livestock manure and the like containing a high concentration of salt is digested by anaerobic microorganisms, the concentration of salt in the anaerobic digester The purpose is to create an environment where microorganisms can continue to survive by lowering the

Another object of the present invention is to lower the salt concentration in an anaerobic digester without adding water.

It is still another object of the present invention to easily lower the concentration of salts in an anaerobic digester without the need for large installations or complex controls.

Another object of the present invention is to lower the salt concentration of the solid sludge obtained by solid-liquid separation so that it can be used as a compost directly without a separate treatment.

In order to achieve the above object, the present invention, in the anaerobic digestion method for producing a biogas by digesting the organic waste by anaerobic microorganisms, the step of injecting digested sludge produced in the anaerobic digestion tank into which the organic waste is introduced into the solid-liquid separation tank ; Solid-liquid separation of the digested sludge from the solid-liquid separation tank; And re-injecting the solid conveying sludge obtained from the solid-liquid separation tank into the anaerobic digestion tank, and by lowering the salt concentration in the anaerobic digestion tank by continuous feeding of the solid conveying sludge, the anaerobic microorganisms will continue to survive. It is characterized in that the production of surplus sludge of the compost cost containing a low concentration of salt.

In addition, when the solid return sludge is re-introduced into the anaerobic digestion tank to reduce the salt concentration of the anaerobic digestion tank below a certain value, discharging a part or all of the solid sludge obtained in the solid-liquid separation tank to the outside as excess sludge It characterized in that it further comprises.

    In addition, by measuring the salinity concentration of the waste water separated from the solid-liquid separation tank to determine whether the use of excess sludge compost, and the waste water separated from the solid-liquid separation tank further comprises the step of discharging to a separate treatment facility It is done.

According to the present invention, when digesting organic waste, such as food waste, sewage sludge, livestock manure, etc. containing high concentration of salt by anaerobic microorganisms, by reducing the salt concentration in the anaerobic digestion tank to create an environment in which microorganisms can continue to survive There is an effect that can be created. Accordingly, it is possible to maximize the treatment efficiency of organic waste by anaerobic microorganisms.

In addition, when treating an organic waste containing a high concentration of salt, the salt concentration can be lowered without adding water, so that a large facility for supplying water is not required.

In addition, the device is simple and easy to install, there is an effect that can be installed at a low cost processing facilities.

In addition, when the salt concentration in the anaerobic digestion tank is measured to be lower than a predetermined value, the solid sludge does not have to be re-introduced into the anaerobic digestion tank, thereby effectively treating organic wastes.

In addition, even in the case of organic wastes having a high salt content, since the salt concentration of the solid sludge obtained by the solid-liquid separation is lowered, there is an effect that can be used directly as a compost.

1 is a process diagram schematically showing an anaerobic digestion method of an organic waste according to an embodiment of the present invention.
FIG. 2 is an overall process diagram illustrating an anaerobic digestion process by the method of extinguishing an organic waste illustrated in FIG. 1.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a process chart schematically showing the anaerobic digestion method of an organic waste according to an embodiment of the present invention, Figure 2 is an overall process diagram showing the anaerobic digestion treatment method of the organic waste shown in FIG.

The anaerobic digestion apparatus of the organic waste according to the present invention includes an anaerobic digestion tank 110 and a solid-liquid separation tank 120.

The anaerobic digester 110 anaerobicly digests organic waste such as food waste, sewage sludge, livestock waste, and the like containing high concentration of salt by anaerobic microorganisms to produce and discharge biogas ⑥ and digested sludge ⑦.

The solid-liquid separation tank 120 performs solid-liquid separation treatment of the digested sludge from the anaerobic digestion tank 110 and re-injects the solid conveying sludge into the anaerobic digestion tank 110.

Thus, by continuously supplying the solid conveying sludge whose salt concentration is lowered by the solid-liquid separation to the anaerobic digester 110, the total salt concentration in the anaerobic digester 110 can be lowered.

As described above, when the concentration of the salt is high, the anaerobic microorganism is difficult to live, according to the present invention can continuously lower the concentration of the salt in the anaerobic digestion tank 110 to maintain the survival environment of the anaerobic microorganisms to maximize the treatment effect can do.

In addition, by lowering the salt concentration in the anaerobic digester 110, it is possible to further lower the salt concentration of the excess sludge. Therefore, the surplus sludge can be directly used as compost without a separate treatment process.

Referring back to FIG. 1, when sufficient time passes after the organic waste ① having a high salt content is added to the anaerobic digestion tank 110, digested sludge ③ is generated in the anaerobic digestion tank 110.

The digested sludge ③ is injected into the solid-liquid separation tank 120 through the lower end of the anaerobic digestion tank 110. The solid-liquid separation tank 120 has a dehydration device (not shown) to separate the digested sludge into a solid and a liquid.

In this process, since the liquid containing a large amount of salt is separated, the salt content of the solid sludge is lowered, and the solid sludge having the low salt content is re-injected into the anaerobic digester 110 as a return sludge ⑫.

Since the conveyed sludge ⑫ is in a state in which the salinity concentration is lowered due to the solid-liquid separation, if the conveyed sludge ⑫ is continuously fed back into the anaerobic digester 110, the total salt concentration in the anaerobic digester 110 can be lowered.

As such, if the salinity of the anaerobic digester 110 is lowered, an anaerobic microorganism in the anaerobic digester 110 may create an environment sufficient for living. Accordingly, it is possible to maximize the digestion efficiency of organic waste using anaerobic microorganisms.

Under these conditions, anaerobic microorganisms digest organic waste to produce biogas ⑥. Biogas ⑥ produced in this process is discharged to the next process.

On the other hand, when the return sludge having a low salt content plays a sufficient role in the anaerobic digestion tank 110 and the salinity concentration in the solid-liquid separation tank 120 is lowered to a predetermined value or less, a part or all of the return sludge ⑫ may be anaerobic digestion tank 110. No need to reload into), just discharge it to the outside with excess sludge 슬.

That is, until the concentration of the salt in the anaerobic digestion tank 110 is below a certain value continuously conveyed sludge into the anaerobic digestion tank 120, and when the concentration of the salt is lowered below a certain value as a surplus sludge 하여 It is to be discharged to the outside.

The excess sludge 배출 discharged in this way is in a low salt concentration state, so it can be immediately used as compost without a separate treatment process.

On the other hand, it is known that the concentration of the salt which can be used for composting is preferably 1% or less. The salinity concentration may be measured directly in the anaerobic digestion tank 110, or the salinity concentration of the anaerobic digestion tank 110 may be adjusted by measuring the salinity concentration of the wastewater separated from the solid-liquid separation tank 120.

The important thing is to maintain the salinity of the excess sludge at less than 1% so that it can be used as compost directly without further treatment.

Then, the liquid ⑪ solid-separated from the solid-liquid separation tank 120 is discharged to a separate wastewater treatment facility.

2, the anaerobic digestion apparatus for organic waste according to an embodiment of the present invention, the hopper 210, shred sorter 220, feed pump 230, mixer 240, the first reservoir 250, A crusher 260, a polymer supply 270, a second reservoir 280, a refinery 285, a generator 290, and a waste heat boiler 295 are included.

Organic waste is injected into the hopper 210. The crushing sorter 220 crushes the organic waste introduced into the hopper 210 to selectively separate the organic waste and the impurities. The feed pump 230 receives the organic waste, the carbon source from the outside, and the return sludge from the crush sorter 220, mixes the same, and supplies the mixed waste to the anaerobic digester 110.

The mixer 240 mixes the digested sludge and the polymer from the anaerobic digester 110 to produce a mixture. The first reservoir 250 stores the contaminants from the shred sorter 220. The first crusher 260 crushes the carbon source and supplies it to the digester feed pump 230. The polymer supplier 270 supplies the polymer to the mixer.

On the other hand, the mixer 240 may be omitted. That is, digestion sludge may be directly supplied from the anaerobic digestion tank 110 to the solid-liquid separation tank 120. In this case, the polymer supply part 270 becomes unnecessary.

The second reservoir 280 stores the biogas from the anaerobic digester 110. The purification tank 285 purifies the biogas stored in the second storage tank 280. The generator 290 receives the biogas purified by the purification tank 285 and generates electricity by generating electricity.

    The waste heat boiler 295 receives heat generated from the generator 290, supplies a portion to the anaerobic digester 110 to maintain the digester temperature, and uses the rest as steam or another heat source.

Hereinafter, the operation of the anaerobic digestion method of the organic waste according to the present invention will be described based on the experimental example.

First, 100 kg ① of organic waste having a salt concentration of 1% is introduced into the input hopper 210 and the organic waste is supplied to the crushing sorter 220.

In the crushing sorter 220, the contaminants ② 5% (5kg) is removed, the remaining 95kg of organic waste ③ is supplied to the digester feed pump 230 in a state of 0.95kg salt concentration 1%.

Here, 5 kg of crushed carbon source ④ passing through the crusher 260 is introduced into the digester feed pump 230. And solid digestion sludge ⑫ 52.458kg (saline concentration: 0.6%) is solid-liquid separated from the solid-liquid separation tank 120.

The digested sludge 된 thus supplied is supplied to the anaerobic digester 110 by the digester feed pump 230 in the state of 157.208kg ⑤ (salin concentration: 0.829%). In the anaerobic digester 110, 9.5kg of biogas ⑥ is produced, and 140kg of digested sludge ⑦ (salt concentration: 0.819%) is discharged.

The digested sludge ⑦ is supplied to the mixer 240. 10 kg of the polymer ⑧ is introduced into the mixer 240 from the polymer supply part 270. Subsequently, 150 kg (saline concentration: 0.765%) of the digested sludge mixed with the polymer is introduced into the solid-liquid separation tank 120.

In the solid-liquid separation tank 120, the digested sludge is solid-liquid separated, solid sludge cake ⑫ 52.458kg (salin concentration: 0.6%) is added to the digester feed pump 230, solid sludge cake ⑪ 10.195kg (salin concentration: 0.6 %) Is supplied to the maturation tank 275.

In addition, the liquid wastewater ⑩ 82.597 kg (saline concentration: 0.9%) that is solid-liquid separated in the solid-liquid separation tank 120 is discharged to the wastewater treatment device (M).

The technical gist of the present invention is to re-inject solid sludge obtained by solid-liquid separation into an anaerobic digester when treating organic wastes containing high salt, thereby reducing the salt concentration in the anaerobic digester without adding water. .

In this way, the environment in the anaerobic digester can be made to live in the anaerobic digester without a large facility for supplying water, and as a result, the organic waste can be efficiently treated.

In addition, when the salinity of the anaerobic digester or the salinity of the waste water obtained from the solid-liquid separator is measured and the salinity in the anaerobic digester is kept below a certain level, the solid sludge is discharged to the outside as surplus sludge without being reintroduced into the anaerobic digester. It is characterized by.

According to the present invention, since the salinity concentration of the solid sludge discharged to the outside can be always maintained at a predetermined value or less, for example, 1% or less, there is an effect that the solid excess sludge can be used directly as compost without a separate treatment process.

Although the present invention has been described as a specific preferred embodiment, the present invention is not limited to the above-described embodiments, and the present invention is not limited to the above-described embodiments without departing from the gist of the present invention as claimed in the claims. Anyone with a variety of variations will be possible.

110: anaerobic digester 120: solid-liquid separation tank
210: hopper 220: shred sorter
230: feed pump 240: mixer
250: first reservoir 260: first shredder
270: polymer supply part 275: sub-age
280: second reservoir 285: refinery
290: generator 295: waste heat boiler

Claims (3)

delete delete Injecting the digested sludge produced in the anaerobic digester 110 into which the organic waste is introduced into the solid-liquid separation tank 120; Solid-liquid separation of the digested sludge from the solid-liquid separation tank 120; Re-injecting the solid conveying sludge obtained from the solid-liquid separation tank 120 to the anaerobic digestion tank 110; anaerobic digestion of organic waste having a high salt content by anaerobic microorganisms to produce biogas In the digestion method,
Part of the solid sludge obtained from the solid-liquid separation tank 120 when the salinity of the solid anaerobic digestion tank 110 is re-introduced into the anaerobic digestion tank 110 to lower the salt concentration below a certain value. Discharging the whole to the outside as surplus sludge,
Determining the availability of excess sludge compost by measuring the salinity concentration of the wastewater separated from the solid-liquid separation tank 120, and discharging the wastewater separated from the solid-liquid separation tank 120 to a separate treatment facility; More,
By continuously adding the solid return sludge to maintain the salinity concentration in the anaerobic digestion tank 110 to a certain value or less to ensure that the anaerobic microorganisms continue to survive, if the salinity of the excess sludge becomes less than 1% A method for anaerobic digestion of organic wastes with high salt content, characterized in that they can be used immediately for composting.

Images