JPH10305762A - Treating method for car washing drainage and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively eliminate oil in car washing drainage by circulating/agitating raw water after a car washing together with ozone containing air, after ozone containing air is injected and an oxidation processing is performed, reacting raw water with a coagulant and alkaline agent and separating and filtering oil and other suspended components from raw water by floating them as flock. SOLUTION: Raw water in a raw water tank 4 storing car washing drainage raw water of a car washing machine 3 is injected into a reaction floating tank 1. Ozone of an ozone generator 6 which is interlocked with a raw water pump 5 is mixed with raw water via an ozone/air mixer 7 in a raw water injection path, and a sterilizing processing and a decomposition processing of harmful components are performed. While raw water circulates within the reaction floating tank 1 together with ozone containing air by a raw water pump 5, inorganic coagulant/alkaline agent/high molecular coagulant are mixed by being injected at prescribed intervals by considering and controlling ph by injection liquid amount. When the raw water pump 5 is stopped for prescribed time, flock of a large particle diameter floats by the completion of coagulant reaction of oil in raw water, a reaction area 1A becomes clear treated water and the water can be recycled for a tank 2 for car washing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating car wash effluent.

[0002]

2. Description of the Related Art In addition to detergents and waxes used during car washing, sediment and oil adhering around the engine are contained in the drainage discharged from gas stations, car washing places and the like. When such drainage is discharged, in areas where the sewerage system is complete, the wastewater is discharged to the sewerage system through drainage pits and drainage channels. If the sewerage system is not complete, the wastewater is discharged to rivers and the like.

[0003] The "Sewerage Law"
If discharged into rivers, they will be subject to the effluent standards specified in each of the Water Pollution Control Laws, including biochemical oxygen demand (BOD), chemical oxygen demand (COD),
Emission standards such as n-hexane extractables (oil content) and suspended solids (SS) must be observed, and some treatment for this is required.

[0004] Oil-containing wastewater treatment methods used in gasoline stations and the like include a treatment method using an adsorbent in the case of non-emulsified oil, a coagulation method by reaction of a coagulant with an alkali component in the case of emulsified oil, and microfiltration. Although there are membrane separation methods such as external filtration and the like, there are problems such as troublesome maintenance and replacement, generation of flocks that are difficult to process, enlargement of equipment, and the like.

[0005]

An object of the present invention is to provide a method for treating car wash effluent which can effectively remove oil contained in raw water (car wash effluent) generated by car washing in a car wash, a gas station, and the like. An object of the present invention is to provide a processing device used for the above.

[0006]

The object of the present invention is to inject ozone-containing air into raw water after car washing and oxidize the same, and to circulate and stir the ozone-treated raw water together with ozone-containing air. Reacting with a flocculant and an alkaline agent to generate oil and other suspended components from raw water as flocs, separating the flocs by floating after circulation and stirring, and separated from raw water by the flocculation reaction. A step of filtering the floc to separate the reduced volume sludge and a dischargeable wastewater, and a step of recycling the treated water obtained by separating the floc from raw water by the reaction as car wash water. This is achieved by a processing method.

An object of the present invention is to provide a raw water tank for storing raw water after car washing with water from a car washing water tank, a raw water pump for supplying raw water from the raw water tank to a reaction levitation tank via a circulation path, An ozone generator attached to a circulation path for ozone treatment of raw water, a mixer for injecting and mixing ozone-containing air from the ozone generator into the raw water, and a chemical solution comprising a coagulant and an alkaline agent are supplied to the reaction flotation tank. A chemical solution injection pump to circulate and stir the ozone-treated raw water and the chemical solution together with the ozone-containing air to circulate the reaction zone and floc generated by flocculation reaction from oil and other suspended components in the raw water. A reaction flotation tank having a flock separation area at the top of the tank that separates and floats from the raw water after stirring, and is separated from the raw water in the reaction flotation tank. Flock discharging device for discharging the floc from the floc separation area by overflow, a floc filter cylinder for separating the discharged floc into sludge and filtrate, and a car washing water tank for treating water obtained by separating the floc from raw water. From a treated water discharge device to be recycled to a raw water pump, an ozone generator, an ozone / air mixer, a chemical liquid injection pump, a floc discharge device, and a control device that controls the operations of the treated water discharge device in a predetermined order. This is achieved by a device for treating car wash effluent.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The method for treating car wash effluent according to the present invention is basically a coagulation method for separating and removing n-hexane extract (oil) suspended in the effluent using a coagulant. Yes, the flocs generated by the flocculation reaction of these oils and the like are floated together with the ozone-containing air injected into the raw water, after being circulated and agitated, accompanied by air bubbles, and separated and removed quickly and completely from the wastewater. Reduce the volume to a form of sludge that can be easily disposed of.

Examples of the flocculant include commonly used inorganic flocculants such as aluminum sulfate, ferrous and ferric sulfates, ferric chloride and polyaluminum chloride, sodium polyacrylate, polyacrylamide, CMC and sodium alginate. Can be used, and these are used alone or in any combination. The inorganic coagulant and the polymer coagulant are used at concentrations of about 100 to 200 ppm and 1 to 5 ppm, respectively, depending on the nature of the raw water to be treated. Generally, sodium hydroxide,
Alkaline agents such as calcium hydroxide and sodium carbonate are used.

The treated water (clarified water) obtained by separating and removing the floc can be discharged to the sewage as it is because the oil content and the like have been sufficiently removed. However, in the present invention, the treated water is not discharged to the system. It is recycled and used as car wash water. This treated water is of sufficient water quality for car washing, and is oxidized simultaneously by injection of ozone-containing air prior to the reaction to sterilize various bacteria contained in the water, as well as putrefactive components and surfactants. Harmful components are also decomposed.

[0011] By recycling the treated water after floc separation without discharging it to a car wash, the amount of tap water used and the sewage treatment load due to the discharge can be reduced. The floc becomes sludge whose volume has been further reduced by the filtration treatment, and only this portion is collected and disposed of as industrial waste.

An apparatus for carrying out the method for treating car wash effluent of the present invention has, for example, a configuration as shown in the system diagram of FIG.

In FIG. 1, reference numeral 1 denotes a reaction floating tank as a main part of the apparatus of the present invention, which comprises a reaction zone 1A for coagulating a raw water and a treatment liquid and a floc separation zone 1B above the reaction zone.
Reference numeral 4 denotes a raw water tank, which is a car washing water tank 2 using tap water or the like.
Is temporarily stored as raw water after car washing and then circulated and supplied to the reaction flotation tank 1.

Reference numeral 5 denotes a raw water pump for circulating and supplying the raw water in the raw water tank 4 to the reaction zone 1A of the reaction floating tank 1. The ozone-containing air from the ozone generator 6 is injected into the raw water in the supply path. An ozone / air mixer 7 for mixing is provided. As shown, the raw water pump 5 turns on / off the solenoid valves 8 and 9.
By turning OFF, the injection of raw water from the raw water tank 4 to the reaction floating tank 1 and the circulation of the injected raw water in the tank are switched. In the figure, reference numeral 10 denotes a solenoid valve for supplying tap water when water is insufficient in the car wash water tank 2.

Numerals 11, 12, and 13 denote chemical solution injection pumps for an inorganic coagulant, a polymer coagulant, and an alkali, respectively. Each of the injection lines is connected to the reaction zone 1A of the reaction flotation tank 1. The injection amount of the alkali agent from the injection pump 13 is controlled by an instruction of a pH meter 14 attached to the reaction flotation tank 1.

The flock separation area 1B of the reaction flotation tank 1 has a space shape whose diameter is reduced upward, and a flock discharge path 1C extending downward from the top is connected to the flock filtration tube 15. The floc filter tube 15 has a filter membrane 15A in the form of a bag-shaped filter paper inside, and a drain valve 16 for filtrate is provided at the bottom of the tube.

Although the flock filtration tube 15 is not specifically shown, in an actual apparatus, a plurality (for example, three) of the reaction flotation tanks 1 are rotatably disposed below the flock discharge passage 1C. During a particular separation cycle of floc / treated water due to agglomeration reaction in the flotation tank 1, one of them is located in the floc discharge path 1C, and after this cycle is completed, it is displaced from the discharge path by, for example, a rotary drive. The next filter cylinder 15 is positioned.

Reference numeral 17 denotes a floc separation area 1B of the reaction flotation tank 1.
An electromagnetic switching valve for discharging tap water for supplying tap water to discharge flocs from the tank from an overflow, 18 an electromagnetic switching valve for discharging treated water for recycling treated water from the reaction tank 1 to the water tank 2 for car washing, 19 This is a sediment drain valve provided at the bottom of the reaction flotation tank 1.

A method of treating car wash effluent by the treatment apparatus of FIG. 1 will be described below. At the start of the treatment cycle, tap water is supplied from the electromagnetic switching valve 10 to the car wash water tank 2, the car is washed in the car wash machine 3, and the raw water as the drainage is stored in the raw water tank 4.

When the raw water in the raw water tank 4 reaches a predetermined value, the raw water pump 5 is driven by a control device (not shown), the electromagnetic switching valve 8 is turned on, and the raw water in the raw water tank 4 is injected into the reaction floating tank 1. In the raw water injection passage, ozone from an ozone generator 6 interlocked with a raw water pump 5 is supplied to an ozone / air mixer 7 and mixed with the raw water to be sterilized by the oxidizing power of ozone and to decompose harmful components. I do. When a water level sensor (not shown) detects that a predetermined amount of raw water has been injected into the reaction levitation tank 1, the electromagnetic switching valve 8 is closed and the electromagnetic switching valve 9 is opened. 5 circulates through the reaction flotation tank 1.

While the raw water is being circulated by the raw water pump 5, an inorganic coagulant, an alkali agent and a polymer coagulant are injected into the reaction floating tank 1 at predetermined intervals and at predetermined injection volumes by a chemical injection pump. The raw water to be circulated is mixed with stirring. Here, the pH of the raw water in the reaction flotation tank 1 is controlled by controlling the injection amount of the inorganic coagulant and the alkali agent based on the instruction of the pH meter 14 so that the pH of the raw water in the reaction flotation tank 1 becomes an optimum value for the coagulation reaction of suspended oil. It is adjusted in the range of 6.5 to 7.5.

After that, when the raw water pump 5 is stopped for a predetermined time, the flocculation reaction by the flocculant such as oil in the raw water is completed to form flocs having a large particle diameter. These flocs contain ozone mixed in the raw water. Along with the air bubbles, it quickly and completely floats on the reduced-diameter flock separation area 1B at the top of the reaction flotation tank 1 and is completely separated from the raw water. The reaction area 1A becomes transparent treated water.

Depending on the nature of the car wash effluent, the flocculation reaction and the accompanying flotation / floating water separation are completed quickly. Here, when the flock discharge electromagnetic switching valve 17 is opened and tap water is injected from below the reaction flotation tank 1, the water level in the tank rises, and the flock floating in the flock separation area 1B at the top of the tank overflows. It is discharged to the lower flock filter tube 15 through the flock discharge path 1C.

The floc discharged here is about 1 to 10% of the volume of the raw water, and the filtrate and the concentrated sludge are gradually dehydrated by filtration through the bag-like filtration membrane 15B provided in the floc filter tube 15. Is separated into The sludge after dewatering is further reduced in volume to 0.1 to 1% of the volume of the raw water, and is subjected to a recovery treatment together with a filter bag as industrial waste. On the other hand, the filtrate separated from the sludge has been sufficiently removed from the flocs due to oil and the like, so that it can be discharged to the sewer as it is. In this case, the amount of filtered waste water is about 1 to 10% or less as compared with tap water initially used for car washing, and the cost of discharging to sewage is significantly reduced.

On the other hand, after the flocs are removed from the floc separating area 1B by overflow, the electromagnetic switching valve 17 for discharging the flocks is closed and the electromagnetic switching valve 18 for discharging the treated water is opened to open the inside of the reaction area 1A of the reaction levitation tank 1. The treated water is recycled to the car wash water tank 2. Here, the oil content of the treated water after the oil content in the raw water is separated as flocs by the coagulation reaction with the flocculant is reduced to an extremely small value compared to the raw water,
It has sufficient water quality for uses such as car washing as so-called middle water supply. However, when the inorganic coagulant used in the coagulation reaction and the neutral salt or the surfactant due to the alkali agent, etc., are left to some extent, a part of the water overflows in the car washing water tank 2 and tap water is added instead. Is preferred. In any case, most of the water in the car wash water tank 2 used in the car washer is supplied as treated water from the reaction levitation tank 1 after the start of the treatment cycle, so that the amount of tap water used for car washing thereafter is 10% or less. To decrease.

In this system, one of the reaction flotation tanks 1
The flocculation reaction of the cycle and the separation of the flocs are completed in a relatively short time, but a certain amount of time is required for the dewatering treatment of the discharged flocs in the floc filtration tube 15. For this reason, in this apparatus, a plurality of flock filter tubes (for example, three) are combined with the reaction flotation tank 1, and these are circled below the flock discharge path 1C led out below the flock separation area 1B of the reaction flotation tank 1. When the floc is filled to a predetermined position in the filter tube 15, the floc filter tube 15 is selectively rotated out of the floc discharge position, and the next filter tube 15 reacts. The floating tank 1 is configured to be pivotally positioned on the overflow discharge path 1C of the flock.

In the case where the separation treatment is continuously performed in the reaction flotation tank 1, when one cycle of floc separation is completed and the floc is discharged to the floc filter tube 15, the next floc filter tube 15 is rotated. Then, it is positioned in the discharge path, and corresponds to the reception of the floc separated from the reaction flotation tank 1 in the next cycle. During the execution of each cycle, the filtration and separation of the flocs are sequentially completed in the other two floc filtration tubes 15, and thus the batch-type and continuous treatment of the car wash drainage is performed. The capacity of the reaction flotation tank 1 is appropriately determined depending on, for example, a daily average amount of water for car washing and the frequency of car washing, and the capacity and the number of the floc filtration tubes 15 are determined accordingly. As described above, since the floc is about 1 to 2% of the raw water volume, the volume of the floc filter tube 15 can be extremely small, and a plurality of floc filter tubes 15 can be compacted below the reaction flotation tank 1 together with other equipment as necessary. It can be arranged in a simple configuration.

In each cycle, the supply, circulation, injection of chemicals, overflow discharge of flocs, and wastewater for recycling of treated water relating to the reaction floating tank 1 are based on indicated values of a water level sensor, a pH meter and the like. The ON-OFF operation of the solenoid valves 8, 9, 17, 18 and the operation of various pumps are not shown. This is all performed automatically by controlling the computer sequentially according to a predetermined program.

[0029]

EXAMPLE The amount of car wash water used for washing each car was 150 liters, and the overflow of treated water in the car wash water tank was 15 liters.
Since simulated raw water containing oils and the like shown in the following table is recycled as liters, it was continuously treated with the illustrated apparatus. The components in the treated water after each cycle were averaged as shown in Table 1 below.
It was as shown in That is, in the first cycle, these components were reduced to a level sufficient to recycle the treated water as car wash water. In the second and subsequent cycles, the treated water recycled from the reaction flotation tank 1 showed almost the same properties on average.

[0030]

[Table 1]

[0031]

According to the present invention, as described above, the raw water as the effluent after being used for car washing is subjected to the coagulation reaction by the coagulant and the alkali agent in the reaction flotation tank while being oxidized by the ozone-containing air. To separate the floc.
After the floc generated by the agglutination reaction is circulated and agitated, the floc is separated from the raw water and floated by entraining the bubbles.Thus, the treated water flows into the floc separation area at the top of the reaction flotation tank. Each is completely and rapidly separated into lower reaction zones.

Further, the separated floc is separated into a sludge and a filtrate which are dehydrated by a floc filter tube, so that the sludge can be disposed of in a form which is easy to handle. There is almost no discharge load to the system. And in the present invention, the treated water separated from the floc by the flocculation reaction on the floc is recycled as washing water, so there is no need to discharge the sewage except for the overflow, and after the system is started, most of the water other than the replenishing water is used. No need for car wash water.

In the apparatus of the present invention, a plurality of floc filtration tubes are provided for the reaction flotation tank in such a manner that they are sequentially switched for each processing cycle. It is possible to effectively combine the time-consuming sludge filtration with the continuous system as a whole.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an outline of an apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Reaction float tank 1A ... Reaction zone 1B ... Flocc separation zone 2 ... Car wash water tank 3 ... Car wash machine 4 ... Raw water tank 5 ... Raw water pump 6 ... Ozone generator 7 ... Ozone / air mixer 8 electromagnetic switching valve for raw water supply 9 electromagnetic switching valve for circulation 10 electromagnetic switching valve for tap water supply 11, 12, 13 chemical injection pump 14 pH meter 16 filtrate drain valve 15 floc filter cylinder 15A: Filtration bag 17: Electromagnetic switching valve for discharging floc 18: Electromagnetic switching valve for discharging treated water 19 ... Drain valve for earth and sand

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C02F 9/00 502 C02F 9/00 502R 502P

Claims (3)

[Claims] 1. A step of injecting ozone-containing air into raw water after car washing to oxidize the raw water, and circulating the ozone-treated raw water together with the ozone-containing air.
Agitating, reacting with a flocculant and an alkaline agent to generate oil and other suspended components from raw water as flocs, floating and separating the flocs after circulation and stirring, and separating from raw water by the flocculation reaction. Carpet wastewater comprising the steps of: filtering filtered floc into sludge of reduced volume and drainable wastewater; and recycling the treated water obtained by separating the floc from raw water by the reaction as carwash water. Processing method. 2. A raw water tank for storing raw water after car washing with water from a car washing water tank, a raw water pump for supplying raw water from the raw water tank to a reaction levitation tank via a circulation path, and ozone-treating the raw water. An ozone generator attached to the circulation path and a mixer for injecting and mixing ozone-containing air from the ozone generator into the raw water; and a chemical liquid injection pump for supplying a chemical liquid comprising a coagulant and an alkaline agent to the reaction flotation tank. The ozone-treated raw water and the chemical solution are circulated and stirred together with the ozone-containing air, and the reaction zone in which floc is generated by an agglutination reaction from oil and other suspended components in the raw water and the generated floc are circulated and stirred. A reaction flotation tank having a flock separation area at the top of the tank for separating and flotation, and a flock separated from raw water in the reaction flotation tank. A floc discharge device that discharges the flocs from the block separation area by overflow; a floc filter tube that separates the discharged flocs into sludge and filtrate; and a treated water obtained by separating the flocs from raw water to a car washing water tank. A raw water pump, an ozone generator, an ozone / air mixer,
A control device for controlling the operations of a chemical liquid injection pump, a floc discharge device, and a treated water discharge device in a predetermined order. 3. A plurality of said floc filter tubes are exchangeably provided in a discharge path of a floc of said reaction levitation tank, and each floc filter tube is connected to a discharge path of the floc at the completion of each separation cycle of flocs in said reaction levitation tank. 3. The device according to claim 2, wherein the position is sequentially switched.