JP2017070938A - Treatment system and method of oil-containing waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment system and method of oil-containing waste water with simple device and control and less expensive by omitting an oil separator process or a process of removing by a skimmer for considering conventional defects that the oil separator process or a process of removing high concentration oil component by the skimmer is needed to be arranged because natural active agent-like materials cannot remove the high concentration oil component in treatment of waste water containing mineral oil or animal and vegetable oil in conventional technologies, especially emulsified oil and fat is difficult to be removed and facilities such as a sand filtration facility or an active carbon treatment facility are needed to be arranged and therefor huge expenditure is needed for initial facilities or maintenance of sand or active carbon.SOLUTION: An oil component removing treatment facility and method having means for supplying oil-containing waste water, means for supplying a surfactant, means for supplying metal salt, means for supplying water-soluble colloidal material and means for aggregation separation, to an oil-containing waste water storage tank having emulsification means.SELECTED DRAWING: None

Description

  The present invention relates to an oil-containing wastewater treatment system and method.

  For wastewater from factories, oil facilities, complex buildings, restaurants, hotels, households, etc., petroleum oil, mineral oil such as refined oil and synthetic oil, vegetable oil such as salad oil, olive oil, animal oil such as lard, milk fat, etc. It is included. Wastewater generated by processing, washing, etc. contains oil, but each facility is obliged to properly treat the wastewater to below the emission standard. In many facilities, when wastewater containing oil flows to a treatment facility, physical treatment or chemical treatment is performed, and if further purification is required, treatment with microorganisms is performed in a subsequent process. However, if a large amount of oil exceeding the processing capacity flows in, the treatment becomes difficult and a problem arises in wastewater purification.

  The activated sludge treatment, which is the current standard wastewater treatment method, causes a shortage of the ability to assimilate by microorganisms when wastewater contains a large amount of oil. Therefore, when the inflow increases, the oil and sludge are combined. Then, it floats to form a thick scum, which is attached to the treatment tank and the stirring device and hinders the operation of the device. Therefore, in the current wastewater treatment, in the case of drainage of high-concentration oil, a method of removing the oil using a skimmer or the like after physically using a pressure flotation device or chemical flocculation is taken and removed. Although the oil is incinerated, it contains a lot of water, which increases the cost of incineration and causes bad odor during storage.

  In activated sludge wastewater treatment that performs solid-liquid separation with a membrane separator, a method of treating oil-containing wastewater by adding saponin, which is a kind of surfactant, as a bioactive auxiliary has been proposed (Patent Document 1). . However, in this method, the oil concentration is limited to a relatively low oil concentration of 200 mg / L or less, and there is a disadvantage that the effect is not produced in wastewater having a concentration higher than this.

  Especially in the treatment of mineral oil, mineral oil assimilating bacteria are very rare, so it is often more difficult than wastewater treatment of animal and vegetable oils. For this reason, wastewater containing a lot of mineral oil needs to be treated with physical and chemical treatments such as pressurized flotation and oil separators to remove most of the oil, and then a complicated process such as sand filtration and activated carbon treatment is required. (Non-Patent Document 1). In addition, biological processing tanks and sand filtration towers are arranged downstream of automobiles and machine parts factories (Non-patent Document 2). These have the disadvantage that the equipment becomes complicated and the initial cost and the running cost for processing increase. .

JP-A-8-267095

"Treatment technology by industry for water and wastewater, Tokyo Denki University Press 190-193 “Treatment technology for water and wastewater by industry, Tokyo Denki University Press, p206 ～ 209

  Conventionally, in the treatment of wastewater containing mineral oil and animal and vegetable oils, high concentrations of oil cannot be removed with natural activator-like substances, and it is necessary to install an oil separator process or a skimmer removal process. . Among them, emulsified oils and fats are difficult to remove, and facilities such as a sand filtration facility and an activated carbon treatment facility have to be provided for supplementary removal. Naturally, enormous costs are required for maintenance of initial equipment and sand and activated carbon. In view of the above-described conventional drawbacks, the present invention aims to provide an oil-containing wastewater treatment system and method that eliminates an oil separator process and a step of removing by a skimmer, and is simple and inexpensive in equipment and management. .

  A means for supplying oil-containing wastewater to an oil-containing wastewater storage tank having an emulsifying means, a means for supplying a surfactant, a means for supplying a metal salt, a means for supplying a water-soluble colloid substance, and a means for coagulating and separating , Oil removal processing equipment and method.

  This is an oil removal equipment and method for emulsifying with at least one nonionic surfactant selected from the group wherein the number of moles of propylene oxide added to the surfactant is 1 or more and 70 or less.

  At least one or more selected from those wherein the water-soluble colloid agent is an amphoteric colloid agent having a colloidal value of plus 0.5 to plus 3.5 meq / g and minus 0.1 to minus 2.7 meq / g. It is the removal processing equipment and method of the oil to be agglomerated.

  It is the oil content removal processing equipment and method which have the characteristics that the said fats and oils are fats and oils containing the processing oil from mineral oil and a mineral oil component.

  The oil removing treatment equipment and method is characterized in that the step of aggregating and separating the oil and fat is installed in the rear part of the tank to which the metal salt and the water-soluble colloid agent are added.

  As in the past, in the treatment of wastewater containing high concentrations of mineral oil and animal and vegetable oils, treatment facilities such as pressurized flotation equipment and skimmer equipment are essential as oil separators, avoiding an increase in initial costs and management costs. I didn't. However, according to the present invention, oil and fat can be directly removed in the emulsified state of oil-in-water droplets, so that conventional oil oil separator process equipment is not required, and oil and fat in drainage can be easily and efficiently removed. I can do it now.

  When considering the salts contained in the waste water, the surfactant of the present invention is preferably a nonionic surfactant over an ionic surfactant. Moreover, in order to remove the fats and oils in the waste water by coagulation and aggregation, the water is obtained by using at least one nonionic surfactant selected from the group having a mole number of propylene oxide addition of 1 or more and 70 or less. A favorable effect is shown for oil droplet emulsification.

  In order for the water-soluble colloid agent of the present invention to agglomerate the emulsified oil in the waste water, the amphoteric colloid agent having colloid values of plus 0.5 to plus 3.5 meq / g and minus 0.1 to minus 2.7 meq / g The use of at least one or more water-soluble colloids selected from those having the above results in a preferable effect of agglomeration and removal.

  Oils and fats, especially those containing mineral oil and processed oil from mineral oil components, are a mixture of various molecules, and it has been difficult to directly emulsify, condense, and agglomerate the oil from this oil-containing wastewater. A processing facility and method that can be used.

  It is a treatment facility and method for oil-containing wastewater that has a more favorable effect that the step of coagulating / aggregating oils and fats emulsifies the wastewater, adding a metal salt and a water-soluble colloid, and installing it at the rear of the tank completely coagulated / aggregated is there.

  Details of the present invention are reported below.

It is a processing-process figure of the oil-containing waste water of the best 1st form for implementing this invention.

  A schematic diagram of the steps and methods of the wastewater treatment method of the present invention is shown in FIG. The oil-containing wastewater storage tank 2 having the emulsifying means is supplied with the oil-containing wastewater from the supplying means 3 and the surfactant is introduced from the supplying means 4 to emulsify, and the metal salt is introduced from the supplying means 5 and condensed to supply water-soluble colloidal substance. It is introduced from the means 6 and aggregated, floated and separated by the oil and fat separation means 7, and separated into treated waste water and oil-containing sludge.

  The oil component of the present invention means an oil component that does not dissolve in water but has a lipophilic group and is liquid at room temperature or liquid when heated to 50 to 60 ° C. Mineral oil in oil includes refined oil such as petroleum crude oil, C heavy oil, B heavy oil, A heavy oil, kerosene, gasoline, etc., and cutting oil and synthetic oil made from petroleum components. Edible oil such as soybean oil, rapeseed oil, sesame oil, corn oil, olive oil, and flaxseed oil that is not usually eaten. Animal fats and oils include animal fats such as pork fat and beef tallow. There are oils and fats inside. Although the present invention is applicable to all oil components, it has a characteristic capable of processing mineral oil such as petroleum crude oil mainly composed of hydrocarbons which are difficult to process.

  Petroleum (crude oil) contains many different oil and fat components such as saturated hydrocarbons, aromatic hydrocarbons, resins and asphaltenes, and also includes resin solid components which are black and dispersed in oil. It is necessary to emulsify these different types of mixed fats and oils, and it is important to balance lipophilicity and hydrophilicity with a nonionic surfactant.

  Surfactant is a substance that has both a hydrophilic part with water properties and an oleophilic part with oil properties. It lowers the surface tension from this structure, making it easy to wet and penetrate. In addition, emulsifying effect that mixes water and oil that do not mix with each other like emulsion or cream with lower interfacial tension, dispersion effect that prevents mixing by separating water and solid particles, and aqueous surfactant solution It has characteristics such as a solubilizing action for dissolving an oil component therein, and a foaming action for stably holding bubbles in the surfactant.

  Surfactants are classified into anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants in terms of molecular structure. Anionic surfactants are those of fatty acid type, alkylbenzene type, higher alcohol type, α-olefin type and the like. Cationic surfactants include alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, amine salts, and the like. Amphoteric surfactants are generally called amino acid-based amphoteric surfactants, and are alkylamino fatty acid salts, alkylbetaines, alkylamine oxides, and the like. Nonionic surfactants include fatty acid esters and amides, higher alcohols, alkylphenols, and the like.

  In the presence of salts, ionic surfactants bind to surfactant ions and solubilized ions, losing the properties of the surfactant, so many types of minerals dissolve in the sea, sewers and industrial wastewater. Therefore, it is difficult to stably emulsify the mineral oil contained therein. On the other hand, the nonionic surfactant of the present invention is suitable for oil spill accidents in seawater and oil-containing wastewater treatment in sewage and factory wastewater because it does not react with minerals and remains stable.

  Specific examples of the nonionic surfactant include alkyl glucoside, polyoxyalkylene glycol, sucrose fatty acid ester, sorbitan fatty acid ester, polyoxyalkylene alkyl ether, polyoxyalkylene ester and the like. In the present invention, a nonionic emulsifier can be used, more preferably polyoxypropylene alkyl ether, polyoxyethylene monoalkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene cholesteryl ether, polyoxyethylene An ethylene polyoxypropylene alkyl ether type is preferable.

  The surfactant of the present invention is a nonionic surfactant of any composition, to which occoside is added, preferably at least one non-ionic surfactant selected from the group having a propylene oxide addition mole number of 1 or more and 70 or less. The use of ionic surfactants is preferred. More preferably, polyoxypropylene butyl ether and polyoxyethylene polyoxypropylene decyl tetradecyl ether are used in the form of at least one nonionic surfactant selected from the group of 1 to 70 moles of propylene oxide added.

  When oil is mixed with water, they separate from each other and the oil floats in the upper layer, but when a surfactant is added and stirred here, the oil becomes turbid and becomes mixed, and when observed with a microscope, clean spherical oil droplets It is observed that the surface of the oil droplets is stabilized in water by covering the surface of the oil droplets, and this action of the surfactant is called an emulsifying action. The emulsified state is called oil-in-water emulsification. The surfactant of the present invention is not particularly limited as long as it is added to form an oil-in-water type emulsification, but preferably a HLB of 7 or more in a mixed system.

  Stirring at this time promotes emulsification, but means for emulsifying two types of liquids that are not mixed include stirring-type emulsification, pressure-type emulsification that makes one liquid finer using pressure, emulsification using ultrasonic waves, and the like. is there. The present invention may be any means as long as the oil particles are emulsified.

The pH is expressed as the number of gram equivalents of hydrogen ions in 1 L of the solution, and is generally defined as pH = −log [H ⁺ ]. In the present invention, pH less than 3.0 is called strong acidity, and is 3.0 or more and 6.0. The following was referred to as acidity, 6 or more and less than 8 was neutral, 8.0 or more and 11.0 or less were referred to as alkalinity, and those exceeding 11.0 were regarded as strongly alkaline. In acidic or alkaline solutions, ionic surfactants have a low emulsifying power, but nonionic surfactants are strong at relatively high pH but often have low emulsifying action at low pH. These surfactants have a characteristic of exhibiting an emulsion stabilizing action in a wide range from strong acid to strong alkalinity.

  The waste water contains fine particles, oil particles, and the like, but a substance having a property of collecting and solidifying colloidal particles having a particle diameter of 1 μm or less is a coagulant. The coagulant is effective in making the colloidal particles in the treated water into small flocs. The colloidal particles that are floating due to electrical repulsion are deprived of repulsive force by the force of ions, and small aggregates by intermolecular force. Make (micro flock). The metal salt related to the present invention plays the role of a coagulant, for example, polyiron and polyaluminum chloride take away the repulsive force by the force of ions from colloidal particles that are electrically repelled in the treated water, and by intermolecular force Make a micro frock.

  There are inorganic coagulants and organic coagulants, both of which have a cation charge, and the fine particles in the wastewater are dispersed by electrical repulsion because the particle surface is charged with anions. The coagulant is bonded to the electrode and electrically neutralized, and the coagulation proceeds. Inorganic coagulants include poly aluminum sulfide (sulfuric acid band), poly aluminum chloride (PAC), poly iron sulfate, ferric chloride and the like. Examples of organic flocculants include polydadomac polydimethyldiallyl ammonium chloride, quaternary ammonium salts of dicyandiamide dicyandiamide resin, polyamine polycondensates of dimethylamine and epichlorohydrin.

  The metal salt of the present invention is an inorganic coagulant and is charged with a cation with a polymer having a relatively small molecular weight, and can bind to an emulsified oil component having a diameter of several tens of millimeters from particles in treated water to form a small flock. . Polyaluminum sulfate, polyaluminum chloride, polyiron sulfate, ferric chloride, and the like can be used, but polyiron sulfate having a molecular weight of 500 to 600 is more preferable.

  A water-soluble loid substance is called a water-soluble colloid that does not settle even when left in water for a long time. The surface is charged and repels each other and is stable. Natural products include anionic sodium alginate, carboxymethylcellulose, cationic chitosan, starch, etc., and synthetic products such as partial hydrolyzate of polyacrylamide, cationic amine formalin condensate, polyaminoalkyl Examples thereof include copolymers of acrylate and polyacrylamide.

In general, since the water-soluble colloidal agent used as a flocculant has a charge, it may be selected based on the magnitude of the opposite charge in order to agglomerate the oil. The colloidal value can be used as the magnitude of the charge amount. As a method for measuring the colloidal value, a sample of 100 ml is taken into a centrifuge tube, and is centrifuged at 3000 rpm for 3 minutes. Add 100 ml of pure water in a 200 ml tall beaker. Add 1 ml of 1 / 200N methyl glycol chitosan (Mgch) to this solution, stir, add 1-2 drops of TB as an indicator, titrate with 1 / 400N potassium potassium sulfate (PVSK) solution (Bml), and measure the blank as well. (Aml). This calculation formula is as follows.
Colloidal value (equivalent) = (BA) / 10 (mL) x 1/400 x 1000 (meq / L)

  An emulsion obtained by emulsifying oil with a surfactant is present in a form in which the hydrophilic group side is negatively charged and dispersed in water. After binding with a positively charged substance such as poly iron sulfate, a polymer water-soluble colloid agent is added to be coarsened and aggregated. Examples of the polymer water-soluble colloid include polyglutamic acid, pectin, and polyacrylamide. In the present invention, an amphoteric water-soluble colloid agent is desirable, and the cationic colloid value is from plus 0.5 meq / g to plus 3.5 meq / g, preferably plus 1.0 meq / g to plus 2.5 meq / g. The anionic colloid value is from minus 0.1 meq / g to minus 2.7 meq / g, preferably from minus 0.3 meq / g to minus 1.2 meq / g.

  After the condensation, when the aggregated solid particles are larger than the density of water, they are gradually settled under the action of gravity, and those smaller than the density of water float on the water. From these properties, sedimentation separation and flotation separation are selected, and in the case of oil, the density is small, so the separation method is flotation separation.

  Conventionally, in the case of oil particles, an emulsion having oil droplets in water is difficult to process. In many cases, an oil layer is formed after demulsification with an acid in advance and then floated under pressure. However, in the present invention, the coagulation / separation may be carried out by solid-liquid separation by floating and coagulating oil droplets that have been emulsified without destroying the emulsion.

  Hereinafter, examples and comparative examples will be described.

  Regarding the emulsifying ability of A heavy oil, (a) a surfactant having a nonionic propylene oxide addition mole number of 17 (Unilube MB-11 ... NOF Corporation), (b) a surfactant having a nonionic propylene oxide addition mole number of 20 The emulsifiability test of the agent (Unilube 20MT-2000B ... NOF Corporation), (c) sorbitan fatty acid ester (NOF Corporation) and their mixed type (d) was conducted. (D) was a mixture of (a), (b), and (c), and the mixing ratio was 3.5 parts, 5.5 parts, and 2.0 parts by weight.

  For sample preparation, add 10 ml of A heavy oil to a 100 ml graduated cylinder, add 10% (V / V) surfactants (a) to (d) as a stock solution of emulsifier to the amount of heavy oil A, and add to ion-exchanged water. To 50 ml. The emulsification conditions were a water temperature of 20 to 22 ° C., and a polytron mixer (TRON PT 1200E, KINEMATICA SUISSE) was used to stir and emulsify for 5 minutes with a rotation speed of 9000 cpr. The mixture was allowed to stand for 30 minutes, and the liquid phase after emulsification was observed and evaluated.

  These results are shown in Table 1. (c) and (d) showed good emulsification, but in an additional test, (c) increased the amount of added oil and fat, and the emulsification phase-inverted and water-in-oil droplets. It became a shape emulsification, and there was nothing suitable alone in the oil removal process. Therefore, the result (d) obtained by various studies from the three types of systems showed the best result.

評価基準は、（５）液が全面乳化している、（４）わずかに上層と下層に境があるが乳化している、（３）乳化層と水層が分離（２）下層に水槽がほとんど分離（１）オイル層が分離している。

Evaluation criteria are (5) liquid is emulsified on the entire surface, (4) the upper and lower layers are slightly emulsified but emulsified, (3) emulsified layer and water layer are separated (2) water tank is in the lower layer Mostly separated (1) The oil layer is separated.

  Sample preparation and emulsification conditions were carried out in the same manner as in Example 1. The tested surfactants were subjected to a comparative test with (d) of Example 1 and other commercially available surfactants. A comparative test product was subjected to a comparative test with Family Fresh (referred to as FF, Kao Corporation) as an ionic surfactant and Tween 80 (ICN Biomedicals, Inc.) as a nonionic surfactant. The mixture was allowed to stand for 30 minutes, and the liquid phase after emulsification was observed and evaluated. In the emulsion in which the pH was changed with sulfuric acid and caustic soda, there was no change in the vicinity of neutrality, but with the change in pH, the emulsion phase changed as shown in Table 2.

  As can be seen from this result, in the emulsification of FF, the aqueous layer was separated from around pH 10 to the lower part, and in Tween 80, the emulsification became unstable near pH 3 and an oil ring was generated. Compared with these, UT2 had a strong ability to emulsify from low pH to high pH.

  A 3.4% saline solution was added to the water tank in the same manner as seawater, and a comparative test of emulsifiability with UT2 and other commercially available surfactants was performed. Sample preparation and emulsification conditions were the same as in Example 1. The surfactant was tested with (d) of Example 1 and other commercially available surfactants. The comparative test product used FF as an ionic surfactant and Tween 80 as a nonionic surfactant, and left standing for 30 minutes after the completion of emulsification, and observed and evaluated the liquid phase after emulsification.

  The results are shown in Table 3, but when the pH was 6.7 or less, the FF and Tween 80 were almost separated from the water tank in the lower layer, and the emulsification became unstable. On the alkali side, the three types of surfactant slightly emulsified the boundary between the upper and lower layers.

  Sample preparation was performed in the same manner as in Example 1, and the surfactant tested was (d) of Example 1. The emulsification conditions were a water temperature of 20 to 22 ° C., a Polytron mixer rotation speed of 5000 cpr, and stirring for 5 minutes to emulsify. 100 ml of this emulsified solution is placed in a 300 ml beaker, adjusted to neutrality, and after adding 2500 mg / l of polyaluminum chloride (Taipac Daiming Chemical Co., Ltd.), an anionic water-soluble colloid having a colloid value (-1.0 meg / g) Agent (ERBIC SETTLER PA-70HS Hinoide Sangyo Co., Ltd.), colloid value (+4.4 meq / g) cationic water-soluble colloidal agent (ERBIC Settler PC-200S Hinoide Sangyo Co., Ltd.), colloid value (+1.5 meq / g and -0.7 meg / g) of an amphoteric water-soluble colloid agent (Erbic Settler PG-230S Hinode Sangyo Co., Ltd.) was used for an aggregation test using 10 mg / l.

  A jar tester (manufactured by Miyamoto Riken Kogyo Co., Ltd.) was used. The results are shown in Table 4. The polymer having a good degree of aggregation was an anion or an amphoteric water-soluble colloid material, but the turbidity was best when the amphoteric water-soluble colloid was used. Turbidity measurement is based on fluoroturbidimetry using kaolin standard solution (according to JIS1010 industrial water standard)

  Sample preparation and emulsification conditions were carried out in the same manner as in Example 4. After taking 100 ml of this emulsified solution into a 300 ml beaker and adjusting it to neutrality, and adding 2000 mg / l of polysulfate (Polytec C, Nittetsu Mining Co., Ltd.) An amphoteric water-soluble colloid agent (colloid values +1.5 and -0.8 meq / g) was added at 5 mg / l to conduct an aggregation test, and turbidity evaluation and hexane extract were measured.

  The agglomeration test was carried out using a jar tester, stirred at a rotation speed of 60 rpm for 10 minutes, and allowed to stand for 5 minutes for comparative examination on the degree of aggregation and turbidity. The degree of aggregation and turbidity were the same as in Example 4, and the hexane extract was performed according to the JAS method. As a result, the degree of aggregation was evaluated as A, the turbidity was 20, and the hexane extract (97.2 mg / 100,000 mg) showed a removal rate of 99.90%.

Industrial usability

  The present invention is used in a process of treating oil-containing wastewater.

2 ... Oil-containing drainage storage tank having emulsifying means, 3 ... Oil drainage supply means, 4 ... Surfactant supply means,
5 ... Metal salt supply means 6 ... Water-soluble colloid substance supply means, 7 ... Aggregation separation means

Claims (5)

  A means for supplying oil-containing wastewater to an oil-containing wastewater storage tank having an emulsifying means, a means for supplying a surfactant, a means for supplying a metal salt, a means for supplying a water-soluble colloid substance, and a means for coagulating and separating Oil removal equipment and method   2. The oil removal treatment facility and method according to claim 1, wherein the surfactant is at least one nonionic surfactant selected from the group having a propylene oxide addition mole number of 1 or more and 70 or less.   The water-soluble colloidal agent is at least one selected from those that are amphoteric colloidal agents having colloidal values of plus 0.5 to 3.5 meq / g and minus 0.1 to minus 2.7 meq / g. The equipment and method for removing oil according to claim 1 or 2   Oil removal equipment and method selected from the claims 1 to 3 wherein the oil contains mineral oil and processing oil from mineral oil components.   The oil removing treatment equipment and method characterized in that the step of aggregating and separating the oil is installed at the rear of a tank to which a metal salt selected from the claims 1 to 4 and a water-soluble colloid agent are added.

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