JP4119331B2 - Car wash wastewater treatment equipment - Google Patents

Description

  The present invention relates to a car wash wastewater treatment apparatus suitable for treatment of wastewater containing wax, machine oil, surfactant, earth and sand, etc. generated by car wash.

  Along with increasing interest in effective use of water resources, demand for water saving for washing water (150L or more per car) that consumes a large amount of tap water, and water quality for dripping down the drainage as it is Concerns about pollution are growing. In particular, the wastewater generated at the car wash station contains not only oil such as wax but also surfactant as well as earth and sand. Surfactants are not easily decomposed naturally, leading to environmental pollution of rivers and lakes. Then, the trial which tries to solve the said subject is made | formed by processing car wash wastewater and reusing treated water as car wash water.

As a treatment method for car wash wastewater and the like, in addition to methods such as sand filtration treatment, coagulation sedimentation treatment, and ozone treatment, a car wash system by filtration equipped with a filter using a hollow fiber membrane disclosed in Patent Document 1 is known. However, in any of the methods, there is a problem that the apparatus is large and it is necessary to secure a wide installation place, and the processing cost becomes high. In particular, regarding the securing of the installation location, since there are various spaces in the car wash, there is a demand for a wastewater treatment apparatus that can be applied without reducing the treatment capacity even in a narrow space.
JP 2000-127913 A JP 2003-93802 A JP 2003-170007 A

  An object of the present invention is to provide a car wash wastewater treatment apparatus that treats wastewater containing oil and surfactant generated in various car wash stations and the like to obtain treated water that can be reused as wash water.

In order to solve the above-mentioned problems, the present invention is a car wash wastewater treatment apparatus for treating wash wastewater containing an oil and a surfactant and reusing it as car wash water,
A coagulation sedimentation section for performing coagulation sedimentation treatment, a membrane separation section for solid-liquid separation of treated water after coagulation sedimentation treatment of car wash wastewater, and a water storage section for storing treated water in the membrane separation section, Provided is a car wash wastewater treatment apparatus using an oil / water separation tank constituting a part of the apparatus as a coagulating sedimentation section to be performed.

  In the present invention, “an oil / water separation tank constituting a part of the apparatus as a coagulating sedimentation section” is not an oil / water separation tank already installed in a car wash station such as a gas station, but is associated with other components as one component of the apparatus. This means that it is a newly established oil / water separation tank.

  When using an existing oil / water separation tank in a car wash station, the position of the car wash wastewater treatment device and the oil / water separation tank may be different depending on the situation of the car wash station. A large installation area and installation space may be required when viewed from the whole apparatus.

  However, the oil-water separation tank is newly installed in association with other components as a component of the car wash wastewater treatment device, so that the entire device can be designed. For this reason, since it becomes easy to adjust the arrangement relationship between the oil / water separation tank and the remaining apparatus (for example, the remaining apparatus can be installed immediately above the oil / water separation tank), the installation area and installation space of the entire apparatus can be further reduced. .

  Furthermore, since the entire apparatus including the oil / water separation tank can be configured, the flow of the liquid to be processed from the oil / water separation tank to the other processing section can be made more efficient, so that the processing capacity can be improved.

  Car wash drainage as referred to in the present invention is drainage produced when vehicles such as various vehicles and trains are washed with wash water containing water, so oil content and surfactant differ depending on the object to be washed. The surfactants are anionic, cationic, nonionic and amphoteric surfactants.

  According to the car wash wastewater treatment apparatus and the car wash wastewater treatment system of the present invention, since the entire apparatus is configured including the oil / water separation tank as the coagulation sedimentation tank, the entire apparatus is made more than the conventional technology while maintaining a high treatment capacity. It can be made compact.

  In addition, when using an existing oil / water separation tank, wastewater other than car wash wastewater also flows in, so it is difficult to separate the oil / water separation tank, and the load on the car wash wastewater treatment device may be excessive. When a new oil / water separation tank is used, the treatment target can be limited to car wash drainage, so the treatment efficiency can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 are conceptual diagrams for explaining the car wash wastewater treatment apparatus or the car wash wastewater treatment system of the present invention, and the installation locations of the respective membrane separation units are different.

  The car wash wastewater treatment apparatus of the present invention includes at least a membrane separation part and a water storage part, and these are connected by pipes or the like, but the wastewater treatment as shown in the figure or not shown in the figure It may include a configuration necessary for performing. 1 and 2, P is a pump, P1 to P4 are pressure gauges, F1 to F2 are flow meters, MV is a flow rate adjusting valve, and the on-off valves are all the same display. 1 and 2 show each component, the connected state of each component, and the wastewater treatment flow, and do not indicate the arrangement of each component or the overall size of the apparatus.

(1) Embodiment 1
The embodiment shown in FIG. 1 will be described. FIG. 1 is a conceptual diagram of the car wash wastewater treatment apparatus of the present invention.

  Car wash wastewater containing oil and surfactant generated at a car wash or the like is collected in a buried oil / water separation tank 1 serving as a coagulation sedimentation section through a drainage pit of the car wash. In the oil / water separation tank 1, rainwater, detergent for cleaning the floor of the facility, miscellaneous wastewater mixed with oil, etc. are not collected, but only car wash wastewater is collected. The miscellaneous wastewater is collected by an existing oil / water separation tank.

  The oil / water separation tank 1 includes a combination of a total of four settling tanks (first tank 11, second tank 12, third tank 13, and fourth tank 14) as shown in the figure. Then, after adding the flocculant, the mixture is stirred and subjected to a coagulation sedimentation treatment to precipitate sand, mud and other large suspended solids (SS). Thereafter, the supernatant liquid of the first tank 11 sequentially passes through the partition walls of the respective tanks and finally flows into the fourth tank 14.

  The flocculant used in the coagulation-precipitation treatment is not particularly limited, but a mixed flocculant of an organic compound and an inorganic compound is desirable from the viewpoint of high removal of oil, and an organic flocculant containing an alginate and / or a cationic polymer flocculant And an inorganic flocculant containing an ionic mineral and / or aluminum sulfate, containing an alginate and a cationic polymer flocculant as an organic flocculant, and containing an ionic mineral and aluminum sulfate as an inorganic flocculant Is preferred.

  The content ratio of the organic flocculant and the inorganic flocculant is 2 to 20% by weight, preferably 4 to 14% by weight, more preferably 5 to 13% by weight, and 98 to 20% by weight of the inorganic flocculant. , Preferably it is 96-86 mass%, More preferably, it is 95-87 mass%.

  The alginate used as the organic flocculant is preferably sodium alginate, and the cationic polymer flocculants are polyamines, polydicyandiamides, cationized starch, cationic poly (meth) acrylamide, water-soluble aniline resin, polythiourea, polyethyleneimine , Quaternary ammonium salts, polyvinyl pyridines, chitosan and the like. Among these, cationized starch, cationized poly (meth) acrylamide or a mixture thereof is preferable.

  When an alginate and a cationic polymer flocculant are included as the organic flocculant, the content ratio (mass ratio shown by alginate / cationic polymer flocculant) is preferably 1: 2 to 2: 1. It is more preferable that it is 2: 3-3: 2.

  Examples of the ionic mineral used as an inorganic flocculant include clay minerals such as montmorillonite and kaolin, zeolite, and the like. Among these, bentonite is inexpensive, has a large adsorption area, and easily adsorbs emulsified oil. And montmorillonite are preferred.

  When an ionic mineral and aluminum sulfate are included as the inorganic flocculant, the content ratio (mass ratio represented by ionic mineral / aluminum sulfate) is preferably 1: 2 to 2: 1, and 2: 3 to 3 : 2 is more preferable.

  As organic flocculants, in addition to the above, acrylic copolymers obtained by copolymerizing hydrophilic monomers such as (meth) acrylic acid and (meth) acrylamide, sodium salts of carboxymethyl cellulose, maleic acid copolymers , Surfactants such as poly (meth) acrylamide, sodium lignin sulfonate, adult starch, polyoxyethylene dipropylamine, polyoxyethylene lauryl ether, polyoxyethylene octylphenyl ether, (meth) acrylic acid and acrylamide Anionic or nonionic polymer flocculants such as copolymers, amphoteric polymer flocculants, low molecular amine flocculants such as propylene diamine, and the like can be included.

  In addition to the above, the inorganic flocculant may contain polyaluminum chloride, magnesium chloride, ferric chloride, ferrous sulfate, ferric sulfate, slaked lime, sodium silicate, sodium aluminate, aluminum alums, etc. it can.

  As the flocculant, when a combination of organic alginate and sodium alginate, a cationic polymer flocculant, and montmorillonite and aluminum sulfate is used, the water treatment ability is improved.

  The flocculant charging and stirring in the oil / water separation tank 1 is performed by the flocculant charging machine 18 and the stirrer 19 attached to the car wash wastewater treatment apparatus, or the flocculant charging machine attached to the oil / water separation tank 1. 18 and a stirrer 19 having a stirrer 19.

  The car wash drainage after the coagulation process stored in the fourth tank 14 of the oil / water separation tank 1 becomes the raw water to be processed by the car wash drainage treatment apparatus. A pump 2a is immersed in the fourth tank 14, and by operating the pump 2a, the water is sent from the line 20 to the raw water storage tank 3 for storage.

  The raw water storage tank 3 may or may not be installed. However, when the raw water storage tank 3 is provided, the raw water storage tank 3 is set to be positioned immediately above the oil / water separation tank 1. Therefore, the line 20 is also short.

  Next, the raw water in the raw water storage tank 3 is sent from the line 21 to the membrane separation unit 4 for solid-liquid separation. The concentrated liquid generated in the membrane separation unit 4 is returned to the first tank 11 of the oil / water separation tank 1 from the lines 31 and 27. The treatment in the membrane separation unit 4 is not particularly limited, but it is desirable to use an internal pressure type hollow fiber membrane module from the viewpoint of compactness. In the case where the raw water storage tank 3 is not provided, the membrane separation unit 4 is set to be located immediately above the oil / water separation tank 1.

  The membrane used in the membrane separation unit 4 is preferably a microfiltration membrane or an ultrafiltration membrane in terms of increasing the water permeation rate, and the membrane material is preferably a hydrophilic membrane material, such as a cellulose derivative type or a polyacrylonitrile type. Examples include hydrophilic polymers, hydrophilic polysulfones, hydrophobic polymers such as hydrophilic polyvinylidene chloride and polyvinylidene fluoride that have been hydrophilized. The membrane shape is preferably a hollow fiber membrane from the viewpoint of compactness.

  Next, the treated water treated in the membrane separation unit 4 can be directly sent from the line 22 to the water storage tank 5 to be stored and reused, but the line 23 can be used between the membrane separation unit 4 and the final water storage tank 7. It is desirable that the activated carbon treatment unit 6 is sent to the activated carbon treatment unit to perform the activated carbon treatment, and the odor component mainly due to oil or the like and the remaining surfactant are removed by adsorption. The contact method of the activated carbon and the treated water in the activated carbon treatment unit 6 is not limited, and for example, a method of passing the treated water through the activated carbon column can be applied. The water storage tank 5 and the final water storage tank 7 are provided with overflow lines 32 and 33, respectively.

  Next, the treated water treated by the activated carbon treatment unit 6 is sent from the line 24 to the final water storage tank 7 to be stored. The water sent to the final water storage tank 7 can be reused as car wash water. By providing the final water storage tank 7 as described above, the reuse of the treated water becomes easy. However, the activated carbon treatment unit 6 is provided between the membrane separation unit 4 and the water storage tank 5, and the treated water treated with the activated carbon is stored in the water storage tank 5. In this case, the final water storage tank 7 becomes unnecessary.

  In the wastewater treatment apparatus of the present invention, the car wash wastewater is treated by the membrane separation unit 4, and optionally further by the activated carbon treatment unit 6. If this treatment is continued, the membrane surface of the membrane separation unit 4 is contaminated. The solid-liquid separation performance may deteriorate due to adhesion. For this reason, it is desirable to maintain the solid-liquid separation performance in a stable state by performing back pressure washing at appropriate intervals.

  The back pressure washing can be applied by a method in which treated water in the water reservoir 5 is press-fitted using the line 26 from the permeate side to the stock solution side of the membrane separation unit 4. The interval of back pressure washing is preferably 15 to 60 minutes, and more preferably 20 to 45 minutes. The flow rate during back pressure washing is preferably 2 to 20 m / day, more preferably 5 to 15 m / day.

  Moreover, in the case of back pressure cleaning, in order to enhance the cleaning effect, a chemical solution such as a sodium hypochlorite aqueous solution from the chemical solution tank 30 can be added to the cleaning water by operating the pump to perform chemical cleaning. When using sodium hypochlorite, the amount of chemical solution added is preferably such that the residual chlorine concentration after backwashing is in the range of 1 to 100 mg / L.

(2) Embodiment 2
Next, the embodiment shown in FIG. 2 will be described. The apparatus shown in FIG. 2 and the apparatus shown in FIG. 1 are the same except that the installation location of the membrane separation unit 4 is different, and can be modified in the same manner as the apparatus shown in FIG.

  In the form shown in FIG. 2, the membrane separation unit 4 is immersed in the third tank 13 and the fourth tank 14 of the oil / water separation tank 1. Thus, instead of using an existing oil / water separation tank, the oil / water separation tank 1 as a coagulating sedimentation part and the membrane separation part 4 and the like can be integrally designed and manufactured and assembled. It can be used as a separation unit. Furthermore, the positional relationship between the membrane separation unit 4 and other components can be easily adjusted.

  In these membrane separation parts 4, solid-liquid separation is performed by operating the suction pump 2b to perform suction. The treatment in the membrane separation unit 4 is not particularly limited, but it is desirable to use an external pressure immersion type hollow fiber membrane module from the viewpoint of compactness. Reference numerals 40 to 44 denote lines connecting the respective parts.

  The treated water after the solid-liquid separation treatment by the membrane separation unit 4 is treated in the same manner as the apparatus shown in FIG. Although the same cleaning method as that of the apparatus shown in FIG. 1 can be applied to the back pressure cleaning method, there is a possibility that the membrane performance may not be recovered only by the back pressure cleaning. In this case, it is desirable to use the air pressure bubbling cleaning by the air diffuser 31 provided below the membrane module by the compressor 32 together with the back pressure cleaning. This air bubbling cleaning is performed constantly or intermittently, and may be performed during filtration in addition to the back pressure cleaning. The amount of air is desirably in the range of the bubble surface linear velocity of 0.01 to 1.0 m / s, and more preferably in the range of 0.05 to 0.5 m / s.

  The car wash wastewater treatment apparatus of the present invention is set so that the treatment amount can be automatically controlled according to the inflow amount of wastewater, or the final amount according to the amount of water used during the car wash work so that smooth car wash work can be performed. It can also set so that the treated water of the water storage tank 7 can be automatically supplied.

  The car wash wastewater treatment apparatus of the present invention uses an oil / water separation tank newly provided as a component of the apparatus as a coagulation sedimentation treatment means. For this reason, the processing means in the apparatus itself can be simplified while maintaining a high processing capacity, and the oil / water separation tank to be a coagulation sedimentation part and other components such as a membrane separation part can be designed as a unit, so that the entire apparatus Can be made more compact.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

(1) Details of the car wash wastewater treatment apparatus The car wash wastewater treatment apparatus shown in FIG. 1 or 2 was used. Details of each part are as follows.

(Oil-water separation tank)
It is an oil / water separation tank consisting of a total of 4 tanks, and the capacity of each tank is 1 m ³ . The first tank is equipped with a flocculant charging machine and a stirrer. As the flocculant, a flocculant containing 48% by mass of bentonite, 48% by mass of aluminum sulfate, 2% by mass of sodium alginate and 2% by mass of cationic polyacrylamide was used. The input amount of the flocculant is 50 mg / L.

(Membrane separation part)
An internal pressure type (the one shown in FIG. 1) or an external pressure type (the one shown in FIG. 2) was used. A cellulose acetate hollow fiber membrane module (membrane area 0.2 m ² , molecular weight cut off: 150,000) was used, and the transmembrane pressure was maintained at 15 kPa. .

(Activated carbon treatment department)
It processed using the column (column capacity | capacitance: 2L) filled with activated carbon (CW130A, Nimura Chemical Co., Ltd. product).

(2) Measuring method (Processing speed)
The value one month after the start of operation was measured with a permeate flow meter (F1 in FIGS. 1 and 2) installed in the membrane separation unit 3.

(COD)
The COD of the treatment liquid for one month from the start of operation was measured with a HACH water quality analyzer.

Example 1
The car wash wastewater treatment apparatus and the car wash wastewater treatment system shown in FIG. 1 were used. The raw water coagulated and precipitated in the oil / water separation tank 1 was treated in the membrane separation unit 3 and the activated carbon treatment unit 6 and stored in the final water storage tank 7. Backwashing was performed at a flow rate of 8 m / day at a rate of 1 minute every 30 minutes.

The treatment amount after one month was 0.02 m ³ / h, and the reduction rate of the treatment amount was 5% or less. The COD value of raw water after 10 months was 10 to 52 mg / L, and the COD value of treated water in the water storage tank 7 was 4 to 10 mg / L.

Example 2
The car wash wastewater treatment apparatus and the car wash wastewater treatment system shown in FIG. 2 were used. It processed with the membrane separation part 4 and the activated carbon processing part 6 which were immersed in the 3rd tank 13 and the 4th tank 14 of the oil-water separation tank 1, and it stored in the last water storage tank 7. FIG. Back pressure cleaning is performed at a flow rate of 8 m / day at a rate of 1 minute every 30 minutes, and air with a film surface linear velocity of 0.2 m / s is provided by the air diffuser 41 provided in the third tank 13 and the fourth tank 14. Aeration was performed at all times.

The treatment amount after one month was 0.02 m ³ / h, and the reduction rate of the treatment amount was 5% or less. The COD value of raw water after one month was 12 to 64 mg / L, and the COD value of treated water in the water storage tank 7 was 5 to 13 mg / L.

The conceptual diagram of the car-wash wastewater treatment apparatus of this invention. Conceptual diagram of the car wash wastewater treatment apparatus of the present invention

Explanation of symbols

1 Oil / water separation tank 4 Membrane separation section 6 Activated carbon treatment section 7 Final water storage tank

Claims (7)

A car wash wastewater treatment device for treating wash wastewater containing oil and surfactant and reusing it as car wash water,
A coagulation sedimentation section for performing coagulation sedimentation treatment, a membrane separation section for solid-liquid separation of treated water after coagulation sedimentation treatment of car wash wastewater, and a water storage section for storing treated water in the membrane separation section, A car wash wastewater treatment apparatus using an oil / water separation tank constituting a part of the apparatus as a coagulating sedimentation section to be performed. The car wash wastewater treatment apparatus according to claim 1, further comprising an activated carbon treatment unit between the membrane separation unit and the water storage unit. The oil / water separation tank that becomes the coagulation sedimentation part, the membrane separation part, the water storage part, and other treatment parts including the activated carbon treatment part, if necessary, are separated, but are placed close together, the oil / water separation tank and the membrane separation part The car wash wastewater treatment apparatus according to claim 1, further comprising means capable of sending liquids to each other. The car wash wastewater treatment apparatus according to any one of claims 1 to 3, wherein the membrane module used in the membrane separation unit is an internal pressure filtration type hollow fiber membrane module. The car wash wastewater treatment apparatus according to claim 1 or 2, which can be used in a state where the membrane separation part is immersed in the oil / water separation tank. The car wash wastewater treatment apparatus according to claim 5, wherein the membrane module used in the membrane separation unit is a hollow fiber membrane module of an external pressure filtration system. The car wash wastewater treatment apparatus according to any one of claims 1 to 6, further comprising means for charging and stirring the flocculant with respect to the oil / water separation tank.

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