KR102078434B1 - Method and device for treating organic wastewater - Google Patents

Abstract

In the treatment of organic drainage by anaerobic biotreatment, aerobic biotreatment, flocculation treatment and flotation or sedimentation separation, RO membrane separation, the alkalinity generated by anaerobic biotreatment is reliably removed by aerobic biotreatment, flocculation, solid solution The amount of flocculant required for separation is reduced, and the salt load of the subsequent RO membrane is reduced. The aerobic biotreatment is routinely treated with an aerobic microorganism attached to the carrier under the conditions of pH 5.5 to 6.5, whereby the alkalinity generated by the anaerobic biotreatment is reliably removed by the aerobic biotreatment.

Description

Method and apparatus for treating organic drainage {METHOD AND DEVICE FOR TREATING ORGANIC WASTEWATER}

The present invention relates to a method and apparatus for treating organic wastewater, and more particularly, to a method and apparatus for further performing reverse osmosis membrane separation treatment after biological treatment of organic wastewater.

In recent years, the recycling of water resources has become important, and treatment and recovery of wastewater have been actively performed. Particularly, membrane separation apparatuses having a fine pore diameter represented by ultrafiltration (UF) membranes or reverse osmosis (RO) membranes are widely used because they can remove high molecular weight organic materials and obtain highly treated water quality. Coming. Since these membrane separation devices have a small pore diameter, when the concentration of organic substances to be introduced increases, organic substances tend to accumulate on the membrane surface, and the increase in filtration resistance becomes remarkable, and water passage becomes difficult. In such a case, it is effective to stabilize the treatment by providing a biological treatment device in front of the membrane separation device and reducing the concentration of organic substances in the wastewater prior to the membrane separation treatment.

Conventionally, as biological treatment at the front end of RO membrane separation, Patent Document 1 proposes a method of sequentially treating organic wastewater by anaerobic biotreatment, aerobic biotreatment, flocculation treatment and flotation or sedimentation separation, and RO membrane separation. It is.

In this method, by applying an anaerobic biotreatment with low generation of biometabolites that contaminate the RO membrane to pretreatment of aerobic biotreatment, RO membrane contamination is reduced, and stable treatment can be continued for a long time.

In the method of patent document 1, there existed the following problems. That is, the alkalinity generated in the process of anaerobic biological treatment remains after the aerobic biological treatment, and the coagulant is consumed by the alkalinity, so that the amount of coagulant added required for flocculation and solid-liquid separation is increased. As a result, the amount of sludge generated in the process increases, the salt load of the RO membrane increases, and the amount of permeated water decreases.

Japanese Unexamined Patent Publication No. 2007-175582

This invention solves the problem of the method of the said patent document 1, removes the alkalinity produced by anaerobic biological treatment reliably by aerobic biological treatment, reduces the usage-amount of flocculant required for flocculation and solid-liquid separation, and of the subsequent RO membrane An object of the present invention is to provide a method and a treatment apparatus for organic wastewater capable of reducing a salt load.

MEANS TO SOLVE THE PROBLEM As a result of repeated examination in order to solve the said subject, as a result of using a support | carrier in aerobic biological treatment, and controlling pH conditions and processing by a daily meal, the alkalinity produced by anaerobic biological treatment was carried out. We found out that we could reliably remove by treatment.

This invention was achieved based on such knowledge, and makes the following a summary.

[1] anaerobic biological treatment process for anaerobic biodegradation of organic wastewater, aerobic biological treatment process for aerobic biotreatment of anaerobic biological treatment water flowing out of the anaerobic biological treatment process, and outflow from the aerobic biological treatment process A method for treating organic wastewater, comprising a solid-liquid separation step of adding a flocculant to the aerobic biological treatment water to be coagulated and then separating solid-liquid and a reverse osmosis membrane separation step of treating the separated water separated in the solid-liquid separation step. The treatment process is a process of processing by aerobic microorganisms affixed to a support under conditions of pH 5.5-6.5, The organic wastewater processing method characterized by the above-mentioned.

[2] The method for treating organic wastewater according to [1], wherein the pH conditions in the aerobic biological treatment step are pH 5.8 to 6.3.

[3] The method of [1] or [2], wherein in the aerobic biological treatment step, the anaerobic biological treatment water is taken into an aerobic biological treatment tank and subjected to aerobic biological treatment, wherein the carrier is a sponge carrier. The carrier filling rate of an aerobic biological treatment tank is 10 to 50%, The processing method of organic wastewater characterized by the above-mentioned.

[4] The method for treating organic wastewater according to any one of [1] to [3], wherein the flocculant is an iron flocculant.

[5] The method for treating organic drainage according to [4], wherein the iron-based flocculant is ferric chloride, and the amount of the iron-based flocculant is 30 to 80 ppm by volume as the amount of FeCl ₃ (38%).

[6] The method for treating organic wastewater according to any one of [1] to [5], wherein the filtered water in which the separated water is filtered is treated in the reverse osmosis membrane separation step.

[7] anaerobic biological treatment means for anaerobic biological treatment of organic wastewater, aerobic biological treatment means for aerobic biotreatment of anaerobic biological treatment water flowing out of the anaerobic biological treatment means, and effluent from the aerobic biological treatment means Organic wastewater having a coagulant addition means for adding a coagulant to the aerobic biological treatment water to be used, a solid-liquid separation means for solid-liquid separation of the water to which the coagulant is added, and a reverse osmosis membrane separation means for treating the separated water separated by the solid-liquid separation means. The treatment apparatus for organic wastewater according to claim 1, wherein the aerobic biological treatment means is a means for treating by aerobic microorganisms attached to a carrier under conditions of pH 5.5 to 6.5.

[8] The treatment apparatus for organic wastewater according to [7], wherein the pH conditions in the aerobic biological treatment means are pH 5.8 to 6.3.

[9] The aerobic biological treatment tank according to [7] or [8], wherein the aerobic biological treatment means is an aerobic biological treatment tank that takes in the anaerobic biological treatment water and aerobics the biological treatment, wherein the carrier is a sponge carrier. The tank carrier filling rate is 10 to 50%, The processing apparatus of organic wastewater characterized by the above-mentioned.

[10] The treatment apparatus for organic wastewater according to any one of [1] to [9], wherein the flocculant is an iron flocculant.

[11] The treatment apparatus for organic wastewater according to [10], wherein the iron-based flocculant is ferric chloride, and the amount of the iron-based flocculant is 30 to 80 vol ppm as the amount of FeCl ₃ (38%).

[12] The organic wastewater according to any one of [7] to [11], further comprising a membrane filtration device for membrane filtration of the separation water, wherein the filtered water of the membrane filtration device is treated with the reverse osmosis membrane separation means. Processing unit.

According to the present invention, since the alkalinity generated by the anaerobic biological treatment can be reliably removed by the aerobic biological treatment which gives up in acidic conditions, the amount of flocculant required for the rearward flocculation and solid-liquid separation can be reduced. As a result, it is possible to reduce the amount of generated sludge and to reduce the salt load of the RO membrane, thereby enabling efficient treatment.

BRIEF DESCRIPTION OF THE DRAWINGS It is a system diagram which shows embodiment of the processing apparatus of organic wastewater of this invention.

EMBODIMENT OF THE INVENTION Below, embodiment of this invention is described in detail.

As shown in FIG. 1, the organic wastewater is used as the raw water, the anaerobic biological treatment is carried out in the anaerobic biological treatment tank 1, and then the aerobic biological treatment is carried out in the aerobic biological treatment tank 2, and the flocculant is added to the aerobic biological treatment water. In the treatment of organic wastewater, after adding and coagulating in the coagulation tank 3, the coagulated treated water is subjected to solid-liquid separation in the solid-liquid separation tank 3, and the separation water is subjected to the RO membrane separation treatment with the RO membrane separation device 5. The carrier is formed in the aerobic biological treatment tank 2 and is biotreated by aerobic microorganisms attached to the carrier under a condition of pH 5.5 to 6.5.

[Organic drainage]

In the present invention, the organic wastewater to be treated may be an organic matter-containing wastewater that is usually biologically treated, and is not particularly limited. Examples thereof include electronic industry wastewater, chemical plant wastewater and food plant wastewater. For example, in the electronic component manufacturing process, a large amount of wastewater containing various organic substances is generated in a developing step, a peeling step, an etching step, a washing step, and the like, and it is desired to recover the wastewater, purify it to a pure level, and reuse it. Is suitable as the wastewater to be treated in the present invention.

Such organic wastewaters include, for example, organic wastewater containing isopropyl alcohol, ethyl alcohol, organic wastewater containing monoethanolamine (MEA), tetramethylammonium hydroxide (TMAH), organic wastewater containing ammonia nitrogen, Organic wastewater containing organic sulfur compounds, such as dimethyl sulfoxide (DMSO), is mentioned.

Anaerobic Biological Treatment

As the anaerobic biological treatment means for anaerobic biological treatment of raw water, any material having an excellent decomposition efficiency of organic matter may be used, and a bioreactor of an anaerobic biological treatment method known in the art can be used.

The anaerobic biotreatment means may be one common formula that performs an acid production reaction and a methane production reaction in the same tank, or may be a two-layer common diet which performs each reaction in another tank. Each reactor may be an arbitrary method such as a floating method (stirring method), a sludge phase method (sludge blanket method), or may be a carrier addition type or a granulated sludge type.

Although it does not specifically limit as an anaerobic biological treatment means, It is preferable to provide an acid production tank and the reaction tank of a UASB (upflow type anaerobic sludge blanket) system from the point which can carry out high load operation.

[Aerobic Biological Treatment]

In the present invention, the aerobic biological treatment is performed by a daily food by a biofilm system in which the activated sludge is adhered to and held on a carrier. In addition, the daily food treatment of aerobic biological treatment does not require concentration control by sedimentation separation, conveyance and drawing of sludge, and thus, operation management is easy. In addition, when agglomeration and removal of the SS generated in the rear stage, some of the remaining organic matter which cannot be removed by biological treatment can be partially removed.

The aerobic biological treatment system may be any microbial system such as fixed bed, fluidized bed or developed bed. As an aerobic biological treatment tank which microorganisms decompose organic matter in an aerobic state, an aeration tank in which oxygen gas supply means, such as an acid pipe, an aerator, etc. for supplying oxygen (air) in the tank can be used.

As the carrier, activated carbon, various plastic carriers, sponge carriers and the like can all be used. However, a sponge carrier is preferable in that it can maintain microorganisms at high concentration. Although it does not specifically limit as a sponge raw material, An ester type polyurethane is preferable. Although there is no restriction | limiting in particular also in the feed amount of a support | carrier, Usually, it is about 10 to 50%, especially about 30 to 50% by the apparent capacity of a carrier with respect to the crude capacity of a biological treatment tank (hereinafter this ratio is called a "fill rate"). desirable.

In this invention, pH in an aerobic biological treatment tank is controlled to 5.5-6.5. For this purpose, although pH may be controlled by adding acids, such as hydrochloric acid and sulfuric acid, to an aerobic biological treatment tank, when nitrogen compound is contained in raw water, since pH will fall by nitrogenation, alkalis, such as sodium hydroxide and potassium hydroxide, may be removed. Adjust by addition. If the pH in the aerobic biological treatment tank is less than 5.5, organic matter decomposition by aerobic biological treatment may be insufficient, and organic matter may remain. If the pH exceeds 6.5, the alkalinity remaining in the anaerobic biological treatment cannot be sufficiently removed. Therefore, pH of an aerobic biological treatment tank is adjusted to pH 5.5-6.5, Preferably it is about 5.8-6.3.

The aerobic biological treatment tank may be 1 breakfast, may be a multi-cooked meal, or may form a partition wall in the bath at 1 breakfast. In the case of a multi-bath type | system | group, it adjusts so that pH of the biological treatment tank of the last stage may be 5.5-6.5, Preferably it is pH 5.8-6.3. In this case, the pH of the aerobic biological treatment tank on the front end side may be about 6.5 to 8.0.

[Aggregation processing]

After anaerobic biotreatment of raw water, aerobic biological treatment water obtained by aerobic biotreatment is agglomerated prior to solid-liquid separation in order to reliably remove microorganisms and high-molecular organic substances by solid-liquid separation means at a later stage. A conventional flocculation apparatus is used for flocculation treatment of aerobic biological treatment water. Only one set may be sufficient as the coagulation tank of this coagulation processing apparatus, and two or more sets may be formed in multiple stages.

Examples of the inorganic coagulant used in the coagulation treatment include iron coagulants such as ferric chloride and polysulfate, and aluminum coagulants such as aluminum sulfate, aluminum chloride, and polyaluminum chloride. Is preferred. These inorganic flocculants may be used individually by 1 type, and may use 2 or more types together.

At the time of agglomeration process, if necessary, it adjusts to pH suitable for the inorganic coagulant used by adding a pH adjuster. For example, it is effective to make it react at pH 5.5 or less in an iron type coagulant, and it is effective to adjust it to pH 6.0 or more after making it react at pH 5.0 or less in an aluminum type coagulant. It is preferable to adjust pH by adding alkali, such as sodium.

The amount of the flocculant added may be an amount from which the required flocculation effect is obtained, and there is no particular limitation, but according to the present invention, since the alkalinity remaining in the anaerobic biotreatment can be highly removed by aerobic biotreatment, for example, chloride 2 In the case of iron-based flocculants such as iron, the amount of FeCl ₃ (38%) added is about 30 to 80 ppm (volume), which can be drastically reduced than before. Can be reduced.

By the flocculation treatment, the soluble organic matter or suspension in the biologically treated water is flocculated. In order to grow this flocculation floc, you may add an inorganic flocculant in a 1st flocculation tank and add a polymer flocculant in a 2nd flocculation tank.

[Solid-liquid separation]

The solid-liquid separation means of the flocculated treated water obtained by flocculating the aerobic biologically treated water is not particularly limited, such as a sedimentation tank, a flotation tank, a centrifugal separator, and the like. In particular, a pressurized flotation tank, particularly a flocculated pressurized float tank, is preferable because it is a device having an area. Moreover, you may use membrane separation means, such as an immersion membrane, for solid-liquid separation of aerobic biological treatment water.

[RO membrane separation treatment]

The separated water obtained by the solid-liquid separation is then treated with a RO membrane separation device to remove dissolved organic matter and dissolved salts remaining in the separated water.

It is preferable to form a filtration apparatus in front of this RO membrane separation apparatus, and to remove SS in water. As a filtration apparatus, the membrane filtration apparatus etc. which used membranes, such as a packed bed type | mold filtration apparatus which filled filter media, such as sand and anthracite, a microfiltration (MF) membrane, an ultrafiltration (UF) membrane, etc. can be used.

In the present invention, the alkalinity remaining in the anaerobic biotreatment is highly removed by the aerobic biotreatment to reduce the amount of flocculant required for the flocculation treatment, so that the salt concentration in the solid-liquid separation water is reduced and the salt load of the RO membrane separation device is reduced. The amount of permeated water of this RO membrane separation device can be increased.

Example

An Example and a comparative example are given to the following, and this invention is demonstrated more concretely.

In the following Examples and Comparative Examples, pH adjustment of the aerobic biological treatment tank and pH adjustment during the flocculation treatment were performed by adding sodium hydroxide or hydrochloric acid to the aerobic biological treatment tank or the aerobic biological treatment water subjected to the flocculation treatment.

Example 1

The organic wastewater of the following water quality liquid crystal plant was used as the raw water, and the treatment was performed at a treatment amount of 1.6 L / d.

<Raw water quality>

pH ： 10

TOC: 100 mg / l

T-N ： 20 mg-N / l

PO ₄ -P ： 0.5 mg-P / ℓ

(Add other trace metals and minerals as nutrients)

The raw water was first passed through the anaerobic biological treatment tank of the following specification in an upflow, and then passed through the aerobic biological treatment tank of the following specification.

<Anaerobic biological treatment tank>

Tank capacity: 4L (cylindrical 10cm in diameter X 50cm in height)

Temperature: 30 degrees Celsius

0.8 liters of anaerobic granules of a beer factory drainage treatment plant and 1.6 liters of polypropylene cylindrical carrier (φ3 mm × 5 mm) were charged, followed by two months of rinsing.

<Aerobic biological treatment tank>

Tank capacity: 4L

Polyurethane sponge (3 mm wide) was added at a filling rate of 40%, and activated sludge (MLSS approximately 6,000 mg / l) from the beer plant drainage treatment facility was poured as seed sludge for 3 weeks.

pH 5.8 to 6.0

To the treated water of the aerobic biological treatment tank, an aqueous solution of 38% by weight ferric chloride (FeCl ₃ ) was added as FeCl ₃ (38%), the amounts shown in Tables 1 and 2, the pH was adjusted to 5.5, and the mixture was agglomerated for 30 minutes. The MFF value was investigated about the supernatant liquid after standing still and settling-separating. Moreover, TOC density | concentration was measured about the filtrate after filtering this supernatant with the filter paper of 0.45 micrometer of pore diameters.

These results are shown in Tables 1 and 2.

Comparative Example 1

In Example 1, it carried out similarly except having adjusted the pH of an aerobic biological treatment tank to 6.8-7.0, and examined the MFF value and TOC density | concentration, and showed the result in Table 1, 2.

Comparative Example 2

In Example 1, it carried out similarly except adjusting the pH of an aerobic biological treatment tank to 4.8-5.0, and investigated the MFF value and TOC density | concentration, and the result was shown to Table 1, 2.

Tables 1 and 2 show the following.

In Example 1, the addition of FeCl ₃ 30 mg / L resulted in a low MFF value of 1.1 and a TOC of 1.5 mg / L, both of which resulted in good water quality. On the other hand, in Comparative Example 1, TOC was not significantly different from the example, but the MFF value did not drop to 1.1 unless FeCl ₃ was added to 75 mg / L. This is considered to be due to FeCl ₃ being consumed due to the alkalinity remaining in the aerobic biological treatment water, and insufficient aggregation at 30 mg / L. In addition, Comparative Example 2, FeCl ₃ 100㎎ / ℓ by the addition of even and TOC and the remaining approximately 5 ㎎ / ℓ, was not reduced by aggregation. This is considered to be because pH of an aerobic biological treatment tank is low, organic substance removal is inadequate, and the low molecular weight organic substance contained in liquid-crystal factory waste water remains.

Although this invention was demonstrated in detail using the specific aspect, it is clear for those skilled in the art for various changes to be possible, without leaving | separating the intent and range of this invention.

This application is based on the JP Patent application 2013-074167 of an application on March 29, 2013, The whole content is integrated by reference.

Claims (12)

Anaerobic biological treatment process for anaerobic biodegradation of organic wastewater, aerobic biological treatment process for aerobic biotreatment of anaerobic biological treatment water flowing out of the anaerobic biological treatment process, and aerobic organisms flowing out of the aerobic biological treatment process In the treatment method of organic wastewater having a solid-liquid separation step of adding the iron-based flocculant to the treated water to react at a pH of 5.5 or less to agglomerate and solid-liquid separation, and a reverse osmosis membrane separation step of treating the separated water separated in the solid-liquid separation ,
The aerobic biological treatment process is a process of processing by aerobic microorganisms affixed to a carrier under the conditions of pH 5.8-6.3, The organic wastewater processing method characterized by the above-mentioned. The method of claim 1,
In the aerobic biological treatment step, the anaerobic biological treatment water is taken into an aerobic biological treatment tank and subjected to aerobic biological treatment, wherein the carrier is a sponge carrier and the carrier filling rate of the aerobic biological treatment tank is 10 to 50%. A method of treating organic wastewater, characterized by the above-mentioned. The method of claim 1,
The iron-based flocculant is ferric chloride, and the addition amount thereof is 30 to 80 volppm as the addition amount of FeCl ₃ (38%). The method according to any one of claims 1 to 3,
Filtrate water obtained by filtering the separated water in the reverse osmosis membrane separation process. Anaerobic biological treatment means for anaerobic biological treatment of organic drainage,
Aerobic biological treatment means for aerobic biological treatment of anaerobic biological treatment water flowing out from the anaerobic biological treatment means,
A flocculant addition means which adds an iron type flocculant to the aerobic biological treatment water which flows out from the aerobic biological treatment means, and makes it react at pH 5.5 or less,
Solid-liquid separation means for solid-liquid separation of the water to which the iron-based coagulant is added;
In the organic wastewater processing apparatus which has the reverse osmosis membrane separation means which processes the separation water isolate | separated by this solid-liquid separation means,
The aerobic biological treatment means is a means for treating the aerobic microorganisms by aerobic microorganisms attached to a carrier under the conditions of pH 5.8 to 6.3. The method of claim 5, wherein
Said aerobic biological treatment means is an aerobic biological treatment tank which takes in said anaerobic biological treatment water and performs aerobic biological treatment, The said carrier is a sponge carrier, The carrier filling rate of the aerobic biological treatment tank is 10 to 50%, It is characterized by the above-mentioned. Device for the treatment of organic drainage. The method of claim 5, wherein
The iron-based coagulant is ferric chloride, the addition amount of which is 30 to 80 ppm by volume as the addition amount of FeCl ₃ (38%). The method according to any one of claims 5 to 7,
And a membrane filtration device for membrane filtration of the separated water, wherein the filtered water of the membrane filtration device is treated by the reverse osmosis membrane separation means. delete delete delete delete

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