JP2008229599A - Drainage treatment method in potato starch production process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drainage treatment method in a potato starch production process where, regarding a large quantity-high concentration protein-containing drainage (decanter drainage) treatment , though there is a problem of high cost equipment investment in a method dealing with the environment in large scale anaerobic fermentation facilities in which aerobic fermentation facilities are coexistent, and further, there is a risk exerting on the environment and a problem of odor in the existent small-scaled facilities, the problems are solved, and the utilization of protein resources is made possible. <P>SOLUTION: Regarding the drainage treatment method in a potato starch production process, the PH of decanter drainage 1 is regulated to 2.5 to 3.5, solid contents such as protein are subjected to precipitation separation (5) by isoelectric point treatment and centrifugal separation, the remaining drainage after the recovery of the solid contents is subjected to neutralization (19) with an organic alkali soil conditioner (lime cake) as sugar plant waste, the supernatant solution is made into an organic liquefied fertilizer, and further, the precipitates can be subjected to field recirculation as a calcium-enriched soil conditioner. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a method in which the decanter wastewater in the potato starch production process adopts an isoelectric point treatment with acid and reforms it into a thorough resource recycling structure.Even if it is an existing facility, it is extremely simple and inexpensive. Make it possible.

In the potato starch manufacturing process, potato is ground and a very large amount of fresh water is repeatedly used to precipitate starch, and the precipitate is dried to obtain starch.
This starch extraction method requires refining with a large amount of fresh water, and involves a huge amount of wastewater treatment. Particularly, the high-concentration protein-containing wastewater (decanter wastewater) has a great impact on the environment, and it is very important to deal with these environmental issues. Expenditure costs.

  Although potato starch production is in a very low profit rate, it is expensive to respond to the environment. Therefore, in reality, potato starch production plants have a small-scale anaerobic treatment (purification by methane fermentation). In order to reduce the amortization of facilities and reduce running costs, a temporary evacuation pool is set up and stored in this pool. In addition, after the processing capacity of the anaerobic fermentation facility is restored, a method of returning to the facility and processing it is taken. However, in this method, a strong rotting odor is generated while the untreated decanter wastewater is evacuated to the evacuation pool, which is an environmental problem.

In most cases not based on these treatments, the concentration of untreated decanter wastewater is reduced to a certain extent and sprayed to the field requiring organic matter reduction. However, even in this method, there is a limit to the fields that can be sprayed, and moreover, a soil-borne fungus (Streptomyces turgidiscabies scabies, etc.) that is a soil infectious disease that affects the potato epidermis grinds the potatoes in the potato starch production process together with the epidermis, Waste such as decanter wastewater resulting from purification is present because it is not sterilized.If decanter wastewater containing this soka disease fungus is sprayed on the field as it is, it will diffuse soka disease fungus. There is concern about proliferation and propagation.
On the other hand, in the recent potato production area, there are many fields lacking calcium, and it has troubled beets, wheat and other crops. Therefore, it is best to supply calcium to a large field by using expensive calcium sulfate or the like. However, since a large amount is required, it is generally supplemented with calcium carbonate that is somewhat inexpensive.

  In order to deal with the above, there are great expectations for technology development means because of the question of technology that also takes protein recovery into account, or the economics and functionality of the plant itself.

  Therefore, high-concentration protein-containing wastewater generated in the starch production process, that is, decanter wastewater, is introduced into the protein precipitation reaction tank, and the protein is precipitated by heat denaturation and / or isoelectric point treatment by addition of steam and / or acid. Soaked in a coagulation tank, and then agglomerated, solid-liquid separated by a solid-liquid separator (centrifugal separator), and the separated liquid is introduced into an anaerobic fermentation treatment tank as a post-treatment to perform anaerobic fermentation treatment. There is a method for increasing the processing efficiency of the fermentation processing liquid. (Patent Document 1)

  In addition, in order to treat high-concentration decanter wastewater, the pretreatment involves separating and removing the protein to reduce the concentration, and at least the isoelectric point treatment even after the pretreatment. There is a processing management method in which anaerobic fermentation processing is performed before isoelectric point processing when the treated waste water after the elapse of time is equal to or higher than a predetermined concentration. (Patent Document 2)

  JP 2001-129590 A   JP-A-2005-349320

In any case, these decanter wastewater treatment methods have sacrificed either the cost of steam (thermal energy) or acid material and its neutralization material as a pretreatment to increase anaerobic fermentation treatment efficiency. The aim is to improve the overall processing efficiency by reducing the protein concentration of the decanter waste water and contributing to the anaerobic fermentation efficiency.
However, under the present circumstances where it is desired to reduce the processing costs for potato starch production, the sacrifice of capital investment and material costs due to the large-scale facility is unacceptable.
However, it is also inconvenient to cause environmental problems such as the rot odor drifting by evacuating the current untreated decanter wastewater to the evacuation pool. In addition, even if the untreated decanter wastewater is diluted and sprayed on the field, the reduced odor causes the original rot odor of the untreated decanter wastewater, which causes pollution problems, and further affects the potato skin. It is inconvenient because the soka disease fungus is sprayed on the field.
Moreover, although the protein precipitated and separated from the decanter wastewater has a high nutritional value, a profitable and specific method for effectively using it as a feed has not yet been shown.
In addition, despite the fact that there are many calcium-deficient fields and they are confused, they are generally only dependent on calcium carbonate, and a better countermeasure is desired.

  An object of the present invention is to obtain a method in which waste including decanter wastewater in the process of producing potato starch is effectively used as a by-product without being subjected to heat treatment.

  In the present invention, in considering all the problems of the potato starch production plant and solving them all together, effective utilization of protein resources in the potato starch production process, energy saving in the production, and further potato potato Contribute to the continuous realization of environmentally friendly agricultural plants and the sustainability of their economic activities through cooperation between pulp (waste) and livestock economic effects. An object of the present invention is to obtain a method capable of constructing an ideal integrated plant.

  The present invention adopts isoelectric point treatment with acid as a pretreatment load reduction of decanter wastewater in the potato starch production process, and in this case, selection of acid and means for using it to meet the added value increase of by-products, It is characterized by the selection of an alkaline agent during neutralization of the acidic residual wastewater after treatment, and the neutralization timing is controlled according to the treatment and purpose of the acidic residual wastewater after treatment, thereby rationalizing various problems around the plant. It is a series of measures to solve.

  In addition, while trying to utilize the actual situation unique to each site and existing facilities, the environment and other inappropriate situations will be resolved, that is, temporary evacuation existing under the small-scale design of anaerobic fermentation treatment facilities It is a method of making improvements using a lorry and a lorry spreader in the depreciation period for returning to the farm. Therefore, it is characterized by providing options to the investment site as a means other than a large-scale remodeling investment in the latest plant.

  In the potato starch production process of the present invention, the decanter wastewater is adjusted to PH 2.5 to 3.5, preferably 3, using acid, and solids such as proteins are obtained by isoelectric point treatment and centrifugation. Since the BOD is lowered to the ultimate, the low-load acidic water (residual waste water after treatment) after the solid content recovery is not neutralized, and the BOD is low even if it is evacuated to the pool for a long time. In addition, the effect of inhibiting deterioration of proteins and the like due to acid retention is to contribute to the prevention of the occurrence of rot odor during evacuation. (Claim 1)

  In the potato starch production process of the present invention, the decanter wastewater is separated from decanter wastewater by isoelectric point treatment with acid and centrifuged to separate solids such as proteins, and low-load acidic water (treatment) After the remaining wastewater) is temporarily evacuated to the pool, the soil infectious fungus (Sowka fungus) that is affected by potatoes is killed in an acidic solution, and then neutralized with an organic alkaline soil conditioner (lime cake) It is to reduce the field as organic liquid fertilizer. (Claim 2)

  In the potato starch production process of the present invention, the decanter wastewater is separated from decanter wastewater by isoelectric point treatment with acid and centrifuged to separate and separate solids such as proteins. It is neutralized with an organic alkaline soil improver (lime cake), which is a factory waste, and the neutralized supernatant water is returned to the field as an organic liquid fertilizer and the precipitate as a soil rich agent rich in calcium. . (Claim 3)

  In the potato starch production process of the present invention, the decanter wastewater is subjected to acid isoelectric point treatment with acid and centrifugal separation to precipitate and separate solids such as proteins, and low-load acidic water (treatment) The post-residual waste water) is neutralized with an alkali agent corresponding to the acid, adjusted to PH 4-11 suitable for post-treatment anaerobic fermentation, and discharged into the river after the anaerobic treatment. (Claim 4)

The waste processing method in the potato starch manufacturing process of the present invention is a method of structurally modifying a conventional facility that has been polarized for potato starch manufacturing and its waste processing into a thorough waste resource recycling plant.
And considering the future energy situation, the treatment method based on the continuous use of the heat source energy will lead to an increase in cost, so by adopting isoelectric point treatment with an acid that does not use this heat energy, Resource added value can be improved by silage and liquid fertilization to the field.

Conventionally, pretreatment to increase the efficiency of anaerobic fermentation treatment was performed by heat-denaturing precipitation of proteins in decanter wastewater or by centrifugal separation after precipitation with acid (electrolyte), but these only increase plant facilities. The running cost was expensive.
Therefore, the BOD can be lowered to the ultimate level by adjusting the decanter wastewater to pH 2.5 to 3.5, preferably 3 with acid, and isoelectric focusing and centrifugation. Odor generation can be prevented and odor improvement problems can be greatly solved.

  And, by adjusting the decanter waste water to pH 2.5-3.5, preferably 3 with acid, and isoelectric focusing and centrifuging, it is possible to precipitate and separate solids such as proteins that can lower the BOD to the ultimate, Thereby, rational formation of a further liquid fertilizer can be performed.

  In addition, the decanter wastewater is adjusted to pH 2.5 to 3.5, preferably 3 with acid, and solids such as protein are precipitated and separated by isoelectric point treatment and centrifugation, and BOD is reduced to the ultimate after treatment. If the acid used for precipitation separation is sulfuric acid, it can be anaerobically fermented by neutralizing to pH 4-11 with sodium hydroxide (NaOH) or the like, and finally the river can be discharged. Become.

At the same time, the potato starch manufacturing plant is the location of the sugar beet sugar factory, and by providing virtually free industrial waste (organic alkaline soil conditioner: lime cake: organic calcium carbonate) in the sugar beet sugar process, which is becoming a pollution problem, Neutralizing strongly oxidized decanter wastewater in the starch production process can be made into effective liquid fertilizer, and this liquid fertilizer can be sprayed on the field.
By the way, in decanter wastewater, high molecular protein is precipitated and removed by isoelectric point treatment with acid and centrifugation, and there are many low molecular weight proteins in the residual wastewater after the treatment. A high molecular weight protein has a large molecule and is less likely to be absorbed than root hair, whereas a low molecular weight protein is small and easy to be absorbed than root hair, so that the root hair becomes fertile and, as a result, the plant grows).

  The wastewater after treatment after precipitation of solids such as proteins by isoelectric point treatment with decanter acid by acid and centrifugation is strongly acidic, so that the soka disease fungus afflicted with potato is killed by this acid It is possible to disperse soka fungus even when sprayed on the field.

  Therefore, the wastewater treatment method in the potato starch production process of the present invention improves efficiency while maintaining the existing small plant, minimizes or cancels the spread of farmland, evacuation of decanter wastewater pool site, or decreases protein concentration and acid It will be possible to solve problems such as septic odor reduction.

The present invention precipitates and separates solids such as proteins by isoelectric point treatment with acid and centrifugation, and an organic alkaline soil improver (lime cake) in which low-load acidic water after the solids recovery is sugar factory waste The neutralized supernatant water can be reduced in the field as organic liquid fertilizer, and the sedimented precipitate after the neutralization is rich in calcium, and the calcium deficient field. The best supplement as a soil conditioner rich in calcium.
In addition, existing calcium-deficient fields are supplemented with calcium sulfate, calcium carbonate, etc., but soka disease, which is widely distributed in the soil of potato production areas, is generally affected by the increase in soil PH. In this respect, by using the precipitate after neutralization with an organic alkaline soil conditioner (lime cake), this precipitate does not increase PH but is expensive. It can be a substitute fertilizer such as calcium sulfate and calcium carbonate that is inexpensive but increases PH, and is a low-cost and high-value soil improver that does not increase PH.

In the present invention, when reducing the decanter wastewater pretreatment load in the potato starch production process, when adopting isoelectric point treatment with acid, acid selection and use means to meet the added value of the factory by-product, The neutralization time can be controlled according to the selection of the alkaline agent in the neutralization of the acidic residual wastewater after the treatment and the disposal and purpose of the acidic water after the treatment.
In addition, the environment and other inappropriate situations can be resolved while making use of the actual circumstances unique to each site and the use of existing facilities.

BEST MODE FOR CARRYING OUT THE INVENTION

  The potato starch production process uses brewing methods to grind potatoes, precipitate the starch by repeatedly using a very large amount of fresh water, and dry it. It is particularly difficult to treat decanter wastewater containing such as.

  Therefore, in the present invention, as shown in FIG. 1, the decanter waste water 1 is repeatedly injected with acid 2, stirred with a stirrer 3, and measured with a PH meter 4 of PH 2.5 to 3.5, preferably 3 The protein precipitation reaction layer 5 is subjected to isoelectric point treatment, the agglomeration progress is measured by the level sensor 6, and the supernatant water 7 and the precipitate 8 are separated.

  The supernatant water 7 when the decanter wastewater is adjusted using an acid and is subjected to isoelectric point treatment to precipitate and separate solids 10 such as proteins is used as the supernatant 11 separated from the precipitate 8 by the centrifuge 9. These are low-load acidic water that is not neutralized after solids are collected, and the soil-borne fungus (sow fungus) affected by potato is killed by being in this low-load acidic water. Therefore, after that, the low load acidic water of the supernatant water is diluted and sprayed 20 to the field as organic liquid fertilizer.

  The sugar beet factory is often established near the potato starch manufacturing factory, and the low-load acidic water of the supernatant water 7 saved and stored in the pool 18 adjacent to the starch factory is discarded in the sugar factory. Organic alkaline soil improver (lime cake), which is a product, is supplied from the sugar factory in the vicinity, and is neutralized by the lime cake infiltration tub 19 adjacent to the pool, and then the supernatant water after neutralization is used as organic liquid fertilizer. Alternatively, the neutralized precipitate may be reduced in the field as a soil conditioner rich in calcium.

  Furthermore, the supernatant water 7 is neutralized 21 to pH 4-11 with sodium hydroxide (NaOH), anaerobically fermented at the anaerobic fermentation treatment facility 22, and further subjected to an aerobic fermentation surface backing 23, which is used as a river discharge 24. It goes without saying.

  The precipitate 8 separated from the supernatant water 7 is applied to a centrifuge 9 and further centrifuged to a solid content 10 such as protein and a separation liquid 11, and the separation liquid is joined to the supernatant water 7, but the protein etc. The solid content 10 is quantitatively extracted to the belt conveyor 13 by the metering pump 12, and is separately discharged in the process of producing potato starch and water-abundant feed such as bran discharged from the tank 14 by the belt conveyor 13. The silage base potato pulp 15 is mixed and adjusted to form a silage base, and the solid content 10 such as the protein is added to the silage base, secondarily mixed by the screw auger 16, fed out, and mixed as a high protein silage The feed 17 is discharged.

Even if the decanter wastewater is evacuated to the pool, the present invention is to reduce the protein and reduce the BOD to the ultimate in order to contribute to the prevention of the generation of rot odor during the evacuation. In order to reduce without using at all, it is to carry out with an isoelectric point and a centrifugal treatment with an acid. The region where more solid content such as protein is precipitated and separated is when the decanter wastewater is adjusted to pH 2.5 to 3.5, preferably 3, by acid, and falls outside this region. (Fig. 2A, Fig. 2B)
Therefore, even if the decanter wastewater is adjusted to PH 2.5 to 3.5, preferably 3, with acid, and the BOD is lowered to the ultimate by centrifuging with isoelectric point treatment, even if this is evacuated to the pool for a long time There is no stink.
Therefore, the post-treatment residual waste water after the solid content recovery without odor of this decanter waste water can be diluted and sprayed on the field as liquid fertilizer.

At present, the anaerobic fermentation treatment capacity is insufficient, and therefore, in factories that inevitably stop decanter drainage and evacuate to the pool for a long time, strong odor is generated during the evacuation period. Depending on the concentration, these are mainly due to protein spoilage. In the present invention, the concentration is adjusted by acid until the end of the raw material acceptance period (that is, the anaerobic fermentation treatment facility is restored), and the concentration by isoelectric point treatment. A method in which the residual wastewater after the treatment after the reduction is saved in an acidic state and neutralized immediately before the anaerobic fermentation treatment is preferable. This makes it possible to control the progress of decay and the accompanying odor generation.
In addition, the protein recovery by the isoelectric point treatment increases the efficiency of the anaerobic fermentation treatment within the operation period, and the pool evacuation can be reduced.

In addition, because the anaerobic fermentation treatment capacity is too low, organic matter may be reduced to the field after diluting the decanter wastewater to a certain concentration or backing it. In this case, however, the pool is inevitably retained. This is because, for reasons such as the number of lorry 10t vehicles used for spraying and the fact that fields after rain cannot be sprayed with muddyness, a pool with a scale of spraying for several days is inevitably required. Also in these cases, there is a diffuse odor in the vicinity of the evacuation pool and by spraying, and there is a high risk of the spread of Souka disease bacteria in the field.
As a reference example, YS broth culture medium adjusted to pH 3-5 with acid was ingested with a spore suspension of the same disease (Streptomyces. Turgidiscabies and S, scabies) and incubated at 25 ° C in a static incubation. Are published (Hokkaido Livestock Experiment Station, Hokkaido Tokachi Agricultural Experiment Station). According to this report, the occurrence and growth of the cells grew at PH 4.5 or higher, but at PH 4.0, PH 3.5, and PH 3.0, they were not detected after 5 days, 2 days, and 1 day, respectively. Has been made.

  Therefore, in the present invention, the decanter wastewater is adjusted to pH 2.5 to 3.5, preferably 3, with acid, and the solid content such as protein is precipitated and removed in the largest amount by isoelectric point treatment and centrifugation. The waste water after the treatment after the minute collection kills the potato fungus diseased by the acid used. After this, neutralize with the organic alkaline soil improver (lime cake), which is the waste of the sugar factory established nearby, and reduce the supernatant water after neutralization to the field as organic liquid fertilizer. Since the precipitate is rich in calcium, it is replenished as a soil conditioner to a calcium deficient field.

By the way, the post-treatment residual drainage adjusted with an acid and subjected to isoelectric point treatment needs to be neutralized in some form, and there is a difficulty in its cost burden. Therefore, although there are several factories where anaerobic fermentation treatment facilities are installed inadequately, many do not own the facilities.
Therefore, not only factories without anaerobic fermentation facilities, but also factories equipped with many organic reduction sprays on the field, each plant is equipped with lorry sprayer equipment.
In addition, when adjusting with an acid and adopting isoelectric point treatment, it can be said that it is preferable to reduce the acidity to about PH6 immediately before spraying. That is, after waiting for the pool at a low pH, a lime cake permeation basket or the like adjacent to the pool is installed, so that a method of pumping and spraying the liquid once passing through the bowl with a lorry spraying vehicle is good. This avoids risks such as acid corrosion of the spreader and is also good for field spraying.
Here, the active ingredient of the lime cake has a water content of about 30%, and is 30% calcium, 0.3% nitrogen, 0.8 phosphoric acid, and 7% organic matter. Although this is unsuitable as a pretreatment neutralizer for anaerobic fermentation treatment due to the nitrogen and organic content, it is rather effective for field reduction spraying. It can also be used as a material.
In addition, since each sugar factory is transferring at a transaction price of about the fare, it can be realized as a neutralizer for a large amount of water at an extremely low cost.

The decanter wastewater is adjusted to pH 2.5 to 3.5, preferably 3, using sulfuric acid, and solids such as proteins are precipitated and separated by isoelectric point treatment and centrifugation, and the treatment after the solids recovery By neutralizing the post-remaining waste water with sodium hydroxide (NaOH) or the like, post-treatment anaerobic fermentation becomes possible, and neutralization is adjusted to PH 4 to 11 suitable for this anaerobic fermentation.
Therefore, what was anaerobically fermented can be released into the river.

Subsequently, in order to investigate the relationship between the protein concentration reduction situation of the wastewater after the isoelectric point treatment, the function and economy of the centrifuge, and the choice of the acid type, the type of PH, acid, the precipitation speed and The precipitation area was investigated. (Fig. 2A, Fig. 2B)
For example, when decanter wastewater adjusted to pH 2,3,4,5 with hydrochloric acid is compared with untreated decanter wastewater, the supernatant water protein concentration after 24 hours after treatment is quantified by the Bradford method. The average value (μg) of the protein amount of PH2, 3, 4, 5 and untreated section remaining in 1 mg of fresh water is 1091, 819, 4565, 5572, and untreated 6086, respectively, and the removal amount is PH3 It was the best. (Some spontaneous precipitation was observed in the untreated decanter)
This is an experiment that takes into account the reproducibility in a 24-hour experiment in view of the temporary evacuation method that is commonly performed by the majority of factories with poor drainage treatment capacity using adjacent pools.
As described above, in the case of other acids, the vicinity of PH3 showed a more preferable tendency. Therefore, an experiment according to the type of acid fixed to PH3 was performed with a new sample (FIGS. 3A and 3B). Hydrochloric acid, sulfuric acid, The average values (μg) of protein in 1 g of supernatant water after 24 hours in formic acid, lactic acid, acetic acid, and untreated were 739, 738, 801, 901, 527, and untreated 5717, respectively. From the above, according to the experimental method, hydrochloric acid, sulfuric acid and acetic acid are considered to be preferable because they have less residual values, but in general, sulfuric acid is advantageous in terms of acid cost, and for silage treatment, it is also particularly advantageous for formic acid. Sex is recognized.
Since high-speed continuous centrifuges specializing in fine particles are generally more expensive than the processing capacity per unit time, only a sedimentation area in which the supernatant water is removed after a certain reaction time has elapsed after installing a separate reaction standby tank. It is also conceivable that the centrifugal separation is advantageous. In this respect, sulfuric acid and hydrochloric acid are very good in both sedimentation speed and pressure density, followed by formic acid. Acetic acid has an extremely slow precipitation rate and is not preferred.

From these things, first, an experiment was conducted in order to grasp the characteristics of the lime cake itself (FIG. 4).
After adding 1 g of lime cake to 100 ml of pure adjusted to PH7, when PH is measured while continuing to stir, the reaction time rises rapidly about 5 minutes after the start of the experiment, and then reaches PH9.51 after 30 minutes. And stable.
Moreover, the decanter waste water which carried out the isoelectric point process by PH3 using 20 wt% sulfuric acid was left still for 24 hours, and protein etc. were precipitated. 100 ml of the supernatant water was collected and used as a sample, and 500 mg of lime cake was continuously added every 5 minutes. After 5 minutes, 10 minutes, 15 minutes, 20 minutes, and 25 minutes. 30 minutes, 35 minutes, and 40 minutes, the PH values of 3.63, 4.25, 4.88, 5.58, 5.84, 5.98, 6.11, 6.24, It became. Therefore, the total accumulated cumulative value of the lime cake dropped 30 minutes after the start of the experiment is 3.5 g. This is considered to be the manifestation effect at 35 minutes after 5 minutes, and can be regarded as having passed the target PH 6.00 with an input amount of 3.5 g.
Therefore, the alkaline agent necessary for raising the decanter waste water that has been subjected to the isoelectric point treatment with PH3 to PH6 is about 350 t of lime cake per 10,000 t of the waste water. Then, it is a charge of about 35 10t vehicles. If the lime cake is 500 to 1000 yen per t, it will cost several hundred thousand yen.
On the other hand, decanter wastewater treated with isoelectric point at PH3 using 20 wt% sulfuric acid was allowed to stand for 24 hours to precipitate proteins and the like. 100 ml of the supernatant water is collected as a sample, and a small amount of sodium hydroxide (NaOH) is continuously added thereto. Then, 742.6 mg was added to PH5.95. Therefore, the amount of sodium hydroxide required to change the PH3 decanter wastewater to PH6 is about 74.26 t per 10,000 t of the wastewater. In the case of sodium hydroxide, if it is about 125,000 yen per t, it will be about 10 million yen.
From the above, there is a significant disparity in expenses.

  It is a flowchart of the waste water treatment method in a potato starch manufacture process.   It is the protein density | concentration determination result table | surface by each PH in the case of hydrochloric acid, and its figure.   It is a protein residual ratio figure in each PH in the case of hydrochloric acid.   It is the protein concentration result table | surface by PH3 in each acid, and its figure.   It is the protein residual rate by PH3 in each acid   It is a lime cake neutralizing power test chart

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Decanter waste water 2 Acid 3 Stirrer 4 pH meter 5 Protein precipitation reaction tank 6 Level sensor 7 Supernatant water 8 Precipitate 9 Centrifugal separator 10 Solid content such as protein 11 Separation liquid 12 Metering pump 13 Belt conveyor 14 Tank 15 Potato pulp 16 Screw -Gar 17 Mixed feed 18 Pool 19 Lime cake 20 Field 21 Neutralization (NaOH)
22 Anaerobic treatment facility 23 Surface bag 24 River

Claims (4)

  Decanter drainage is adjusted to pH 2.5-3.5, preferably 3, using acid, solids such as proteins are precipitated and separated by isoelectric point treatment and centrifugation, and BOD is lowered to the ultimate. Even if the low-load acidic water (residual waste water after treatment) after solids recovery is not neutralized and saved to the pool for a long period of time, the BOD is low and the deterioration-preventing effect of proteins and the like due to acid retention is reduced. A wastewater treatment method in a potato starch production process, which contributes to prevention of the generation of rot odor during evacuation.   For decanter wastewater, solids such as proteins are precipitated and separated by isoelectric point treatment with acid and centrifugation, and low-load acidic water (residual wastewater after treatment) after this solid content recovery is temporarily saved in the pool, After eradicating potato-affected soil infectious agents (souka disease) in an acidic solution, neutralize with an organic alkaline soil conditioner (lime cake), which is a sugar factory waste, and then reduce it to the field as organic liquid manure. The waste water treatment method in the potato starch manufacturing process of Claim 1 characterized by the above-mentioned.   An organic alkaline soil improver (lime cake) in which the solid content such as protein is precipitated and separated from decanter wastewater by acid isoelectric point treatment and centrifugation, and the low-load acidic water after recovery of this solid content is sugar factory waste. The waste water in the potato starch production process according to claim 2, wherein the neutralized supernatant water is converted into organic liquid fertilizer and the precipitate is reduced in the field as a calcium-rich soil conditioner. Processing method.   Decanter wastewater is adjusted to pH 2.5-3.5, preferably 3, using acid, and solids such as proteins are precipitated and separated by isoelectric point treatment and centrifugation, and the low load after recovery of the solids Acidic water (residual waste water after treatment) is neutralized with an alkaline agent corresponding to the acid used for precipitation separation, adjusted to PH 4-11 suitable for anaerobic fermentation as post-treatment, and discharged into the river after anaerobic fermentation treatment A wastewater treatment method in the potato starch production process.

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