JP2018199109A - Treatment method of water containing nonionic surface active agent and water treatment method - Google Patents

Abstract

Nonionic surfactant-containing water treatment method for efficiently removing nonionic surfactant in nonionic surfactant-containing water, and RO water supplied with treated water with reduced nonionic surfactant concentration by this method A water treatment method for membrane treatment is provided. An adsorption step for obtaining permeated water having reduced nonionic surfactant concentration as treated water by passing water containing nonionic surfactant as feed water through a microfiltration membrane or an ultrafiltration membrane, and an alkali agent , An anionic surfactant, and an oxidant in contact with the microfiltration membrane or ultrafiltration membrane, and a desorption step of desorbing the nonionic surfactant adsorbed on the filtration membrane Method for treating agent-containing water. A water treatment method for treating the treated water with an osmotic membrane. [Selection] Figure 1

Description

  The present invention relates to a method for treating nonionic surfactant-containing water, which removes the nonionic surfactant from water containing the nonionic surfactant. The present invention also relates to a water treatment method for reverse osmosis (RO) membrane treatment of water from which the nonionic surfactant has been removed by the method for treating nonionic surfactant-containing water of the present invention.

  Currently, wastewater recovery is actively performed due to the shortage of water supply worldwide. In many cases, non-ionic surfactants are contained in cleaning wastewater in the electronics industry, transportation machinery industry, and the like. Nonionic surfactants are low molecular weight compounds that are hardly decomposable, and are difficult to remove even by agglomeration treatment or biological treatment. Nonionic surfactants can be eliminated in RO membranes, but are pollutants that lower the permeation flux of polyamide-based RO membranes, which have become the mainstream in recent years. Therefore, nonionic surfactants contain water containing nonionic surfactants. Using water as the RO membrane supply water is a major obstacle to stable operation. Moreover, it is difficult to recover the performance of the RO membrane contaminated with the nonionic surfactant by washing, and this also makes it difficult to collect the waste water containing the nonionic surfactant.

When water containing nonionic surfactant is used as supply water, there is a method of passing water at a pH of 9.5 or more as a means for not reducing the permeation flux of the RO membrane (Patent Document 1). In this method, a relatively stable permeation flux can be obtained. However, there are problems in that a large amount of an alkaline agent is required to make the feed water alkaline, and the quality of the permeate is deteriorated.
Prior to the RO membrane treatment, a method has been proposed in which a nonionic surfactant is adsorbed and removed with an adsorbent simulating a polyamide structure (Patent Document 2). However, this method does not consider the regeneration of the adsorbent, and a technique for removing the nonionic surfactant more easily is required in view of the labor and cost of producing a special adsorbent.

  In addition, a method of cleaning the RO membrane using a cleaning agent suitable for cleaning the RO membrane contaminated with the nonionic surfactant has been proposed (Patent Documents 3 and 4). The membrane performance can be recovered by cleaning the RO membrane, but it is necessary to stop the RO membrane processing device for the RO membrane cleaning, and the RO membrane treatment frequently occurs when the contamination with nonionic surfactant is severe. The problem is that the device must be stopped.

Japanese Patent No. 4496795 Japanese Patent No. 3864817 Japanese Patent No. 4458039 Japanese Patent Laid-Open No. 2015-97991

  The present invention relates to a method for treating nonionic surfactant-containing water that efficiently removes nonionic surfactant in water containing nonionic surfactant, and treated water in which the concentration of nonionic surfactant is reduced by this method. It is an object to provide a water treatment method for RO membrane treatment.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a nonionic surfactant is adsorbed on a microfiltration (MF) membrane or an ultrafiltration (UF) membrane, and the adsorbed nonionic surfactant is an alkaline agent, In order to remove the nonionic surfactant from the nonionic surfactant-containing water, it can be desorbed with an anionic surfactant or an oxidizing agent. The present invention was developed by finding that a method of repeating the steps was effective.

  That is, the gist of the present invention is as follows.

[1] An adsorption step in which water containing nonionic surfactant is supplied as feed water and permeated through a microfiltration membrane or ultrafiltration membrane to obtain permeated water having a reduced concentration of nonionic surfactant as treated water; an alkali agent; A nonionic surfactant having a desorption step of bringing at least one of an anionic surfactant and an oxidizing agent into contact with the microfiltration membrane or the ultrafiltration membrane and desorbing the nonionic surfactant adsorbed on the filtration membrane Treatment method of contained water.

[2] The method for treating nonionic surfactant-containing water according to [1], wherein the concentration of the nonionic surfactant in the feed water is 20 mg / L or more.

[3] The method for treating nonionic surfactant-containing water according to [1] or [2], wherein the nonionic surfactant has not undergone biological treatment.

[4] The microfiltration membrane or ultrafiltration membrane is a polyvinylidene fluoride filtration membrane, a cellulose filtration membrane, a polyethersulfone filtration membrane, or a polytetrafluoroethylene filtration membrane [1] to [3 ] The nonionic surfactant containing water processing method in any one of.

[5] The method for treating nonionic surfactant-containing water according to any one of [1] to [4], wherein the oxidizing agent is hypochlorous acid and / or a salt thereof.

[6] A water treatment method characterized by subjecting treated water obtained by the method for treating nonionic surfactant-containing water according to any one of [1] to [5] to RO membrane treatment.

  According to the present invention, the nonionic surfactant in the nonionic surfactant-containing water can be efficiently removed, and stable RO membrane treatment using treated water with reduced nonionic surfactant concentration by this method as supply water Can be performed continuously.

6 is a graph showing a change with time of permeation flux when a POEOPE aqueous solution is passed through in Experimental Example 1. 5 is a graph showing a change in permeation flux with time when a POEPSPE aqueous solution in Experimental Example 1 is passed through.

  Hereinafter, embodiments of the present invention will be described in detail.

[Method for treating nonionic surfactant-containing water]
The method for treating nonionic surfactant-containing water according to the present invention uses water containing nonionic surfactant as feed water to permeate through a microfiltration (MF) membrane or ultrafiltration (UF) membrane, and the concentration of the nonionic surfactant An adsorption step for obtaining permeated water with reduced water as treated water, and a nonionic interface adsorbed on the filtration membrane by bringing at least one of an alkali agent, an anionic surfactant, and an oxidizing agent into contact with the MF membrane or UF membrane A desorption step of desorbing the active agent.
In the present invention, “filtration” and “permeation”, “filtrate” and “permeated water” are synonymous.

<Supply water>
The feed water according to the present invention is water containing a nonionic surfactant, and the nonionic surfactant contained in the feed water is not particularly limited. For example, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl Ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene polyoxypropylene glycol, sorbitan fatty acid ester, fatty acid glyceride, pentaerythritol fatty acid ester, propylene glycol mono fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester , Polyoxyethylene alkylamine, fatty acid alkanolamide and the like. Of these, polyoxyethylene nonionic surfactants are preferred from the viewpoint of adsorptivity to MF membranes or UF membranes. Examples of polyoxyethylene nonionic surfactants include polyoxyethylene lauryl ether and polyoxyethylene stearyl. Ether, polyoxyethylene oleyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene polystyryl phenyl ether, polyoxyethylene lauric acid ester, polyoxyethylene stearic acid ester, polyoxyethylene polyoxypropylene Examples include glycol, polyoxyethylene sorbitan monolaurate, and polyoxyethylene sorbitan monooleate.

  In the feed water which concerns on this invention, only 1 type of these nonionic surfactants may be contained and 2 or more types may be contained.

  Although there is no particular limitation on the concentration of the nonionic surfactant in the feed water, the present invention, as shown in Comparative Examples 1 to 4 below, cannot be removed by a coagulation treatment with a normal inorganic coagulant. It is effective for feed water containing a nonionic surfactant at a high concentration, and feed water having a nonionic surfactant concentration of 20 mg / L or more, for example, about 20 to 2000 mg / L is preferred.

  Such nonionic surfactant-containing water is not particularly limited, and examples thereof include cleaning wastewater in the electronics industry and transport machinery industry, process wastewater in the food industry, cosmetic industry, and domestic wastewater.

  In addition, since a nonionic surfactant is decomposed | disassembled halfway and it becomes difficult to adsorb | suck to MF film | membrane or UF film | membrane, the thing which is not biologically processed for a nonionic surfactant is preferable.

<Adsorption process>
In the present invention, the supplied water is passed through the MF membrane or the UF membrane, and the nonionic surfactant in the water is adsorbed on these filtration membranes to be removed.

  Examples of the material of the MF membrane or UF membrane include cellulose-based materials such as cellulose acetate (CA), cellulose mixed ester (CE), polyethersulfone (PES), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE). Any of these may be used. Hydrophobic PVDF and PTFE are preferably subjected to hydrophilic treatment to increase water permeability. That is, it is thought that adsorption occurs when the hydrophilic group of the nonionic surfactant interacts with the hydrophilic portion of these membranes.

  As shown in Examples 1-1 to 1-6 below, depending on the membrane material, the nonionic surfactant has different adsorptive properties and desorbing properties. Since it is not suitable for continuous use, it is preferable to select and use an appropriate membrane material in accordance with the purpose of treatment in consideration of the amount of adsorption and the amount of desorption.

  As for the pore sizes of the MF membrane and the UF membrane, the smaller the nonionic surfactant adsorption amount, the larger the pore size. On the other hand, the larger pore size is preferable from the viewpoint of water permeability and pressure loss. Therefore, although it depends on the coexisting substances and required characteristics for processing, the pore diameter of the MF membrane is preferably 0.01 to 1 μm, particularly 0.01 to 0.45 μm. The pore diameter is preferably 0.002 to 0.01 μm, particularly preferably 0.005 to 0.01 μm.

  The nonionic surfactant concentration in the permeated water (treated water) obtained in the adsorption step using the filtration membrane described above varies depending on the use of this treated water (how to treat this treated water further). When this treated water is RO membrane treated according to the water treatment method of the invention, the nonionic surfactant concentration is preferably as low as possible for stable operation of the RO membrane treatment, although it depends on the nonionic surfactant concentration of the feed water. In order to obtain permeated water with a nonionic surfactant concentration of 1 mg / L or less by adsorbing and removing 20 mg / L or more of the nonionic surfactant in the feed water with an MF membrane or UF membrane, It is preferable to select and appropriately control the operating conditions of the adsorption process, the conditions of the subsequent desorption process, and the like.

<Desorption process>
In the present invention, at least one of an alkaline agent, an anionic surfactant, and an oxidizing agent is brought into contact with the MF membrane or UF membrane that has adsorbed the nonionic surfactant in the feed water in the above-described adsorption step, and adsorbed on the filtration membrane. The nonionic surfactant is desorbed.

  As the alkali agent used for desorption of the nonionic surfactant, inorganic alkali agents such as sodium hydroxide and potassium hydroxide are preferably used.

  Moreover, as an anionic surfactant, 1 type (s) or 2 or more types, such as alkyl benzene sulfonates, such as sodium dodecylbenzene sulfonate, alkyl sulfates, such as sodium dodecyl sulfate and sodium octyl sulfate, can be used.

  Oxidizing agents include hydrogen peroxide, peracetic acid, percarbonate, halogen oxoacids such as hypochlorous acid and their salts (eg, alkali metal salts, alkaline earth metal salts), peroxides, chlorine, bromine, One or more of halogens such as iodine can be used. Of these, hypochlorous acid and hypochlorite are preferable from the viewpoints of oxidizing power, ease of handling, and cost.

  In the desorption step in the present invention, a solution containing one or more of these alkali agents, anionic surfactants, and oxidizing agents (hereinafter sometimes referred to as “desorption solution”) adsorbs the nonionic surfactant. The MF membrane or UF membrane is preferably allowed to permeate, or the MF membrane or UF membrane is back-washed with this desorption solution.

  The desorption liquid is preferably an aqueous solution containing about 0.01 to 1% by weight of an anionic surfactant and adjusted to an alkalinity of about pH 11 to 13 with an alkaline agent. In such a desorption liquid, the desorption liquid is adsorbed on the filtration membrane. When the nonionic surfactant cannot be sufficiently desorbed, if the oxidizing agent is further about 0.01 to 5% by weight, hypochlorous acid and / or a salt thereof, the effective chlorine concentration is 0.001 to 1. It is preferable to treat the filtration membrane with a desorption solution added to a concentration of about% by weight.

  In the desorption step, when the adsorption performance of the MF membrane or the UF membrane is reduced in the adsorption step, for example, the nonionic surfactant concentration of the permeated water obtained by passing the feed water is 5 of the nonionic surfactant concentration of the feed water. % May be performed, or may be performed periodically, for example, after an adsorption process for a predetermined time or after allowing a predetermined amount of supply water to permeate.

  In the desorption step, the composition and pH of the desorption solution, the amount of desorption solution, and the time of the desorption step so that 50% or more, for example, 80 to 100% of the nonionic surfactant adsorbed on the MF membrane or UF membrane in the adsorption step can be desorbed. Etc. are preferably controlled.

  According to the present invention, the adsorption process and the desorption process are alternately repeated, and the nonionic surfactant adsorbed on the MF film or the UF film in the adsorption process is desorbed in the desorption process. Nonionic surfactant adsorptivity can be recovered, nonionic surfactant in water containing nonionic surfactant is efficiently removed, and treated water with low nonionic surfactant concentration suitable as RO membrane supply water, etc. Can be obtained.

[Water treatment method]
The water treatment method of the present invention is a RO membrane treatment of treated water having a reduced nonionic surfactant concentration by the above-described nonionic surfactant-containing water treatment method of the present invention, and the RO membrane is treated with a nonionic surfactant. Stable RO membrane treatment can be performed by preventing contamination and resulting reduction in permeation flux.

The material of the RO membrane used for the RO membrane treatment is not particularly limited, and for example, a polyamide RO membrane, a cellulose ester RO membrane, a polysulfone RO membrane, a polyimide RO membrane, or the like can be used. Among these, the effect of the present invention can be remarkably obtained when a polyamide RO membrane having a large influence of a decrease in permeation flux due to the nonionic surfactant is used.
Moreover, there is no restriction | limiting in particular also in the form of the RO membrane module used for RO membrane treatment, For example, a tubular module, a plane membrane module, a spiral module, a hollow fiber module etc. can be used.

  Hereinafter, the present invention will be described more specifically with reference to examples.

<Nonionic surfactant>
The following were used as nonionic surfactants.
Polyoxyethylene (10) octyl phenyl ether “Triton X-100” (hereinafter abbreviated as “POEOPE”) manufactured by Kishida Chemical Co., Ltd.
Polyoxyethylene polystyryl phenyl ether “DTD51” (hereinafter abbreviated as “POEPSPE”) manufactured by Takemoto Yushi Co., Ltd.

<Desorption drug>
The following were used as the alkaline agent and anionic surfactant for desorption.
Sodium hydroxide (6N solution): manufactured by Kishida Chemical Co., Ltd. sodium dodecyl sulfate: manufactured by Wako Pure Chemical Industries, Ltd. (hereinafter abbreviated as “SDS”)
Sodium hypochlorite solution: Wako Pure Chemical Industries, Ltd.

<Filtration membrane>
The following was used as the MF membrane and UF membrane of the filtration membrane.

<MF membrane>
MCE-M membrane: Cellulose mixed ester MF membrane (pore diameter 0.22 μm) manufactured by Merck Millipore
MCE-Ms membrane: Cellulose mixed ester MF membrane (pore size 0.025 μm) manufactured by Merck Millipore
MCE-A membrane: Cellulose mixed ester MF membrane (pore size 0.2 μm) manufactured by Advantech
PES membrane: polyethersulfone MF membrane (pore diameter 0.22 μm) manufactured by Merck Millipore
PVDF membrane: hydrophilic polyvinylidene fluoride MF membrane (pore diameter 0.22 μm) manufactured by Merck Millipore
PTFE membrane: hydrophilic polytetrafluoroethylene MF membrane (pore diameter 0.2 μm) manufactured by Merck Millipore
CA membrane: Cellulose acetate MF membrane (pore size 0.2 μm) manufactured by Advantech

<UF membrane>
PVDF-UF membrane: hollow fiber polyvinylidene fluoride UF membrane (pore diameter 0.01 μm) manufactured by Toray Industries, Inc.

  Further, the nonionic surfactant concentration in the liquid was measured by fluorescence analysis using a fluorescence analyzer “Aqualog” manufactured by Shimadzu Corporation.

[Adsorption removal and desorption of nonionic surfactant by MF membranes of different materials]
<Example 1-1>
The MCE-M membrane was placed in a plastic holder PFA-47 manufactured by Advantech, and 100 mg / L of POEOPE aqueous solution was filtered three times at a time as raw water, and the POEOPE concentration of the filtrate was measured each time. Next, 10 mL of 0.15 wt% SDS aqueous solution adjusted to pH 12 with sodium hydroxide (6N solution) was passed through the MF membrane adsorbed with POEOPE by permeation of the aqueous nonionic surfactant solution, and the resulting filtrate was obtained. The POEOPE concentration of was measured.

<Example 1-2>
The same procedure as in Example 1-1 was performed except that a PES film was used as the MF film.

<Example 1-3>
The same operation as in Example 1-1 was performed except that a PVDF membrane was used as the MF membrane.

<Example 1-4>
The same procedure as in Example 1-1 was performed except that a PTFE membrane was used as the MF membrane.

<Example 1-5>
The same operation as in Example 1-1 was performed except that an MCE-A film was used as the MF film.

<Example 1-6>
The same operation as in Example 1-1 was performed except that a CA film was used as the MF film.

  Table 1 (Table 1A to Table 1F) shows the POEOPE concentration of the filtrate during adsorption and desorption in Examples 1-1 to 1-6, and the adsorption amount and desorption amount obtained from this concentration. Moreover, the ratio (percentage) of the desorption amount with respect to the total adsorption amount is also shown as the desorption rate (%).

Table 1 shows the following.
In any of the Examples, at the time of adsorption, 20% or more of POEOPE in the raw water is adsorbed and removed in the first 10 mL. The cellulose mixed ester membranes MCE-M and MCE-A have a large amount of adsorption, but all adsorbed POEOPE is not desorbed. The PES film, PVDF film, and PTFE film have a small amount of adsorption, but all adsorbed POEOPE is desorbed. In the case of these membranes, the amount of desorption is larger than the amount of adsorption due to the fact that a part of POEOPE remains on the filtrate side and the error in the amount of liquid and measurement values. The CA membrane has a smaller amount of adsorption than the MCE-M, A membrane and more than the PES membrane, but has a low desorption rate.

[Adsorption and removal of nonionic surfactant by MF membrane with small pore size]
<Reference Example 1>
An MCE-Ms membrane having a pore diameter of 0.025 μm was placed in a plastic holder “PFA-47” manufactured by Advantech, and 100 mg / L of POEOPE aqueous solution was filtered 10 times each as raw water, and the POEOPE concentration of the filtrate was measured.
Table 2 shows the POEOPE concentration and the adsorption amount in the filtrate.

  As is clear from Table 2, the POEOPE concentration in the filtrate was kept at 1 mg / L or less up to a filtrate volume of 50 mL as compared with the result of Example 1-1 using an MCE-M membrane having a pore diameter of 0.22 μm. ing. From this result, it can be seen that the adsorption amount can be increased by reducing the pore size of the MF membrane to be used.

[Adsorption removal and desorption of nonionic surfactant by UF membrane]
<Example 2>
Using a PVDF-UF membrane, a minimodule (6 hollow fibers, membrane length 10 cm, effective membrane area 26.4 cm ² (= 4.4 cm ² × 6)) was produced. A 100 mg / L POEOPE aqueous solution as raw water was passed through this hollow fiber membrane under conditions of water flux of 1 m / d, flow rate of 1.8 mL / min, and time of 5 min to adsorb POEOPE.
Next, a 0.15 wt% SDS aqueous solution adjusted to pH 12 with sodium hydroxide (6N solution) was used as the desorption liquid for the UF membrane on which POEOPE was adsorbed, flux 1 m / d, flow rate 1.8 mL / min, time 5 min. The backwashing was performed under the backwashing conditions.
This water flow and backwashing were repeated 5 times alternately. The permeated water obtained by passing water and the backwashing solution obtained by backwashing were collected and the POEOPE concentration was measured respectively.
Table 3 shows the POEOPE concentration and adsorption amount of the permeated water at the time of water-passing adsorption, and the POEOPE concentration and desorption amount in the backwash liquid at the time of backwash desorption.

  As is apparent from Table 3, POEOPE in the 100 mg / L concentration POEOPE aqueous solution is adsorbed and removed by the UF membrane, and the POEOPE concentration of the permeated water is reduced to 1 mg / L or less. In this example, the POEOPE desorption amount by backwashing is less than the adsorption amount by water flow, so the pH of the backwash solution is increased, the SDS concentration is increased, and an oxidizing agent such as sodium hypochlorite is added. Thus, it is necessary to use a stronger backwash solution.

[Adsorption removal and desorption of different nonionic surfactants]
<Reference Example 2>
The PVDF membrane was placed in a plastic holder “PFA-47” manufactured by Advantech Co., Ltd., and 50 mg / L of POEPSPE aqueous solution was filtered three times by 10 mL as raw water, and the POEPSPE concentration of the filtrate was measured each time.

<Example 3-1>
After an adsorption operation for filtering 10 mL of POEPSPE aqueous solution, a desorption operation was performed by passing 10 mL of 0.15 wt% SDS aqueous solution adjusted to pH 12 with sodium hydroxide (6N solution) as a desorption solution, and this adsorption and desorption was performed three times. The procedure was the same as in Reference Example 2 except that the procedure was repeated.

<Example 3-2>
After the adsorption operation of filtering 10 mL of POEPSPE aqueous solution, 0.1% by weight of sodium hypochlorite as an effective chlorine concentration is added to 0.15 wt% SDS aqueous solution adjusted to pH 12 with sodium hydroxide (6N solution) as a desorption solution. The same procedure as in Reference Example 2 was performed, except that a desorption operation was performed to allow 10 mL of what was added to be%, and this adsorption and desorption were repeated three times.

  The filtrate concentration of POEPSPE during adsorption and desorption in Reference Example 2 and Examples 3-1 to 3-2 is shown in Table 4 (Tables 4A to 4C).

Table 4 shows the following.
In Reference Example 2, in the first filtration, the POEPSE concentration of the filtrate is reduced to about 40% relative to the raw water, and 60% of POEPSPE is removed. The POEPSPE that was removed decreased with the second and third rounds.
In Example 3-1, 60% of POEPSPE that had been adsorbed was desorbed in the desorption process, and the second and third adsorptions were stably repeated.
In Example 3-2, POEPSPE detected from the filtrate at the time of desorption decreases. This is thought to be due to the decomposition of POEOPE by sodium hypochlorite. From this result, it is considered that desorption can be efficiently performed by using an oxidizing agent such as sodium hypochlorite in combination.

[Removal of nonionic surfactant by coagulation with inorganic coagulant]
<Comparative Example 1>
A 40 mg / L polyaluminum chloride aqueous solution (Al concentration 5.3 wt%, Sankei Kasei Co., Ltd., PAC) is added to 20 mg / L POEOPE aqueous solution (raw water), and the mixture is agglomerated by stirring at 150 rpm for 15 minutes at pH 7. did. The agglomerated water was filtered through a hydrophilic polyvinylidene fluoride MF membrane (pore diameter: 0.1 μm) manufactured by Merck Millipore, and the POEOPE concentration of the filtrate was measured.
In the filtration process for measuring the POEOPE concentration, 30 mL of co-wash was performed to eliminate the influence of the adsorption of POEOPE to the MF membrane, and the filtered water obtained after the adsorption of POEOPE to the MF membrane broke through. Was used as a measurement sample.

<Comparative Example 2>
The same procedure as in Comparative Example 1 was performed except that the amount of PAC added was 60 mg / L.

<Comparative Example 3>
The same procedure as in Comparative Example 1 was performed except that the PAC was replaced with a polyferric sulfate aqueous solution (Fe concentration: 11.0% by weight or more, manufactured by Nittetsu Mining Co., Ltd.).

<Comparative example 4>
The same procedure as in Comparative Example 2 was performed except that PAC was replaced with an aqueous polyferric sulfate solution.

  Table 5 shows the POEOPE concentrations of the raw water and the agglomerated treated water in Comparative Examples 1 to 4.

From Table 5, it can be seen that even when the nonionic surfactant concentration is 20 mg / L, the nonionic surfactant can hardly be removed by the coagulation treatment with the inorganic coagulant.
On the other hand, as shown in the above-mentioned examples, the adsorption removal by the MF membrane and the UF membrane can reduce the nonionic surfactant having a concentration of 100 mg / L by 20% or more, Depending on the pore size and operating conditions, it can be made 1 mg / L or less, and the effectiveness of the present invention is clear.

[Confirmation of RO membrane contamination by nonionic surfactant]
<Experimental example 1>
Using “ES20” manufactured by Nitto Denko Corporation as the RO membrane, operation was performed by passing a nonionic surfactant aqueous solution under conditions of a temperature of 25 ° C., a permeation flux of 1 m ³ / (m ² · d), and a recovery rate of 80%. The change in pressure was measured. As nonionic surfactants, POEOPE and POEPSPE were used, and the concentrations were 0.1, 1, and 10 mg / L, respectively.
FIG. 1 and FIG. 2 show the converted permeation flux [m ³ / (m ² · d)] at 0.75 MPa obtained from the measured operating pressure. The converted permeation flux is obtained by the following formula.
Equivalent permeation flux = 1 x 0.75 / operating pressure

  1 and 2, it can be seen that POEPSPE has higher film contamination than POEOPE. It can also be seen that POEOPE can reduce film contamination by setting the concentration to 1 mg / L or less, and POEPSPE to a concentration of about 0.1 mg / L.

Claims (6)

  An adsorption process that allows permeated water containing nonionic surfactant as feed water to pass through a microfiltration membrane or ultrafiltration membrane to obtain permeated water having a reduced concentration of nonionic surfactant as treated water, and an alkali agent and anionic surfactant A nonionic surfactant-containing water having a desorption step of bringing at least one of an agent and an oxidizing agent into contact with the microfiltration membrane or ultrafiltration membrane and desorbing the nonionic surfactant adsorbed on the filtration membrane Processing method.   The processing method of the nonionic surfactant containing water of Claim 1 whose density | concentration of the nonionic surfactant of the said feed water is 20 mg / L or more.   The method for treating nonionic surfactant-containing water according to claim 1 or 2, wherein the nonionic surfactant has not undergone biological treatment.   The microfiltration membrane or ultrafiltration membrane is a polyvinylidene fluoride filtration membrane, a cellulose filtration membrane, a polyethersulfone filtration membrane, or a polytetrafluoroethylene filtration membrane. The processing method of nonionic surfactant containing water as described in claim | item.   The method for treating nonionic surfactant-containing water according to any one of claims 1 to 4, wherein the oxidizing agent is hypochlorous acid and / or a salt thereof.   The water treatment method characterized by carrying out RO membrane treatment of the treated water obtained by the processing method of the nonionic surfactant containing water of any one of Claims 1-5.

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