JPH07121323B2 - Wastewater treatment equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment device, and more particularly to a wastewater treatment device for reusing wastewater from a vehicle cleaning device for automobiles used in gas stations and the like.

[0002]

2. Description of the Related Art Generally, car wash wastewater treatment is intended to treat suspended substances such as mud and dust, water-soluble wax, surfactants and dyes. Since flocculation is suitable for treating suspensions, waxes, and dyes, as car wash wastewater treatment at gas stations, flocculation and flocculation such as flocculation sedimentation, flocculation and flotation, and sand filtration There are many combinations of. However, since these devices require a flocculation tank, a flocculate separation tank, a sand filtration tank, and a backwash water tank (washing water for filtered sand), the installation area of the equipment is large, and operation management is difficult. Furthermore, there is a problem that the cost of the device is high and it is difficult to save water.

FIG. 2 shows a sludge blanket type waste water treatment apparatus which is one of the coagulation treatment methods, 1 is a mortar type tank for forming a precipitation tank, and 2 is a partition formed by a conical partition wall 3 in the tank 1. A mixing chamber 4, a variable speed stirring blade arranged in the mixing chamber 2, 5 a drive motor thereof, 6 and 7 supply pipes for supplying raw water and a flocculant to the upper portion of the mixing chamber 2, and 8 a An opening formed in the lower portion of the conical partition wall 3 is a treated water outflow pipe provided in the upper portion of the tank 1.

In this type of wastewater treatment apparatus, the flocs generated in the mixing chamber 2 pass through the lower opening 8 of the conical partition wall 3 into the tank 1 and rise in the tank 1, but the inside of the tank 1 is upward. Since the cross-sectional area increases as it goes to, the ascending velocity also decreases accordingly, and the sedimentation velocity of the flocs and the ascending velocity of the liquid are balanced at a certain cross-sectional height to maintain a constant interface. A sludge blanket layer will be formed in the tank 1. Thereafter, when the flocs from the mixing chamber 2 pass through this layer, only the treated water filtered by this layer and removed to fine flocs is discharged from the treated water outflow pipe 9, while the sludge formed in the layer 1 is discharged. Is settled and concentrated on the bottom of the tank 1, and is removed from the bottom of the tank.

[0005]

In the wastewater treatment equipment of the type described above, flocculation and floc separation can be carried out in one tank, so that the equipment becomes compact, and in terms of performance, the outflow of fine flocs is the smallest. However, it has not been put to practical use in a small apparatus with a treatment capacity of 3 m ³ / hour or less such as a car wash wastewater treatment apparatus. There are two reasons for this.

[0006] One of the reasons is that when the conventional sludge blanket type wastewater treatment equipment is stopped, the sludge blanket layer that captures the fine flocs settles down, so even if the sludge blanket layer is restarted, the sludge blanket layer remains. It takes time to form a predetermined height, and during that period, fine flocs flow out considerably, so that it is unsuitable as a car wash wastewater regeneration treatment device of a gas station, which is repeatedly operated and stopped several tens of times a day.

Another reason is the treatment of the generated sludge. In the ordinary sludge blanket type, the flocs above the sludge blanket layer are settled at the settling part to prevent the sludge blanket layer from rising. Since it comes to flow out from the treated water outflow pipe, the actual device makes considerable efforts to prevent this. However, there is still floc carry-over, and the coagulation-sedimentation-treated water needs to be sand-filtered. In addition, when the sludge that has settled in the settling section is automatically discharged, it is necessary to install a device that monitors the height of the sludge that has been set up, frequently observe the sludge settling state, and adjust the sludge discharge. However, if this is not done, the inside of the device may become full of sludge and a large amount of flock may flow out.

The present invention eliminates the above drawbacks.

[0009]

The waste water treatment apparatus of the present invention comprises a separation tank for liquid and sludge, a mechanism for introducing a mixed liquid of waste water and a flocculant into the lower portion of the separation tank, and an upper portion of the separation tank. The treated water discharge mechanism, the mixed solution discharge mechanism provided approximately in the middle of the separation tank , and the middle and upper portions of the separation tank.
During the wastewater treatment operation suspension period, which connects the lower part of the separation tank.
It is characterized by comprising a circulating pump operated .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the wastewater treatment equipment of the present invention will be described below with reference to the drawings.

In the present invention, as shown in FIG. 1, a car wash drainage 12 in a pit 11 is added to a static mixer 15 together with an aggregating agent 13 and an aggregating auxiliary agent 14 by a pump 10 and mixed, and this mixed solution is stored in a separation tank 16. It is jetted into the separation tank 16 from a pipe-shaped distributor 17 having a large number of holes arranged in the lower part.

A mixed liquid discharge pipe 18 having a large number of holes is arranged at a height approximately in the middle of the separation tank 16, and the mixed liquid discharge pipe 18 is connected to an external discharge pipe 20 via an automatic electric valve 19. At the same time, the mixed liquid discharge pipe 18 and the distributor 17 are connected to each other by a circulation pump 21 which is operated during the drainage treatment operation stop period . Also, the above separation tank 16
A treated water discharge pipe 22 having a large number of holes is arranged at the upper part of, and the treated water is discharged through the treated water discharge pipe 22.

Since the waste water treatment apparatus of the present invention has the above-mentioned structure, the car wash waste water 12 is rapidly mixed with the coagulant 13 and the coagulant aid 14 in the static mixer 15, and this mixed liquid is provided in the lower part of the separation tank 16. , Jetted from a pipe-shaped distributor 17 having a large number of holes, and as a result, the mixed liquid is rapidly stirred to generate flocs.

The generation of the flocs takes some time, but once the flocs are generated, the generated flocs become nuclides for the next floc formation, and thereafter, the fine active flocs are generated in a short time. Will be generated. This fine active floc is a sludge blanket layer 23 formed by a mixed liquid containing the floc in the separation tank 16.
During its rise, it effectively contacts the flocs in this layer 23 and is trapped within this layer 23.

When the sludge blanket layer 23 captures the fine active flocs, the sludge increases and the interface of the sludge blanket layer 23 rises, but a part of this increasing sludge is discharged together with the liquid through the automatic electric valve 19 to the external discharge pipe. Emitted from 20. The water from which the flocs are almost completely separated rises further and is discharged from the treated water discharge pipe 22.

When the apparatus stops the above processing and the pump 10 stops, the circulation pump 21 is operated to operate the mixed liquid discharge pipe 1
If the sludge blanket is sucked from 8 and supplied to the distributor 17, an upward flow of the mixed water is generated from the distributor 17 and the sedimentation of the interface of the sludge blanket layer is prevented.

In the present invention, a part of the sludge is discharged to the outside through the external discharge pipe 20 without being subjected to precipitation treatment.
This sludge discharge amount is 18 to 2 of the mixed water inflow amount to the device.
It is 5%, and the regeneration rate of car wash wastewater is said to be about 70% in consideration of the concentration of dissolved substances. Therefore, this sludge discharge amount of 18 to 25% is convenient from the perspective of regeneration rate.
Since there is no dead space in the settling tank in this sludge blanket layer, old sludge does not remain and rot, and therefore the odor of the regenerated water is very low and there is no problem in use. Further, if the sludge discharge amount is 30 to 40% larger than the sludge generation increase amount, the sludge blanket layer does not rise above the sludge discharge position and flow out from the treated water discharge pipe 22, and a constant height is always maintained. It is easy to hold and does not require the difficult management of traditional sludge blanket wastewater treatment equipment. Furthermore, since the rising speed of the flocs in the separation tank rapidly decreases at the sludge discharge position, there is almost no detachment (peeling) of the flocs from the sludge blanket layer, and the suspended solids in the coagulated water are always several mg / liter or less. And can be kept very low. This allows the use of disposable pleated cartridge filters that could not be used with conventional coagulated treated water due to high filter cost, so there is no need for a conventional sand filtration device, and regenerated treated water with higher transparency is ensured. Moreover, it can be obtained with a compact and inexpensive device.

While the operation of the processing apparatus is stopped, the height of the sludge blanket layer can be kept constant by operating the circulation pump 21 at all times, but it may be operated intermittently to save power consumption. In this case, in order to recover the sludge blanket layer that has settled while the circulation pump is stopped in a short time, even if the circulation flow rate is increased slightly, the flocs in the sludge blanket layer that have expanded too much are sucked into the circulation pump 21 and circulated. Therefore, the sludge blanket layer can always be kept at a constant height. Therefore, no matter how often the operation is restarted, the processing can be performed in the best state, and the processing is very stable.

The rising speed of the sludge blanket layer is preferably 3 to 5 m / hour for coarsening flocs and capturing fine flocs. If this speed is too fast, a large amount of flocs will separate from the sludge blanket layer. On the other hand, if the velocity is slow, a part of the flocs will settle, and a good fluidized sludge blanket layer will not be formed.

Table 1 shows the processing conditions of the present invention, and Table 2 shows the processing performance.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

As described above, according to the wastewater treatment apparatus of the present invention, there is a great advantage that wastewater can be efficiently treated with an extremely simple structure.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a wastewater treatment device of the present invention.

FIG. 2 is an explanatory diagram of a conventional wastewater treatment device.

[Explanation of symbols]

 1 Tank 2 Mixing Chamber 3 Conical Partition Wall 4 Stirring Blade 5 Drive Motor 6 Supply Pipe 7 Supply Pipe 8 Opening 9 Treated Water Outflow Pipe 10 Pump 11 Pit 12 Car Wash Drain 13 Coagulant 14 Coagulation Aid 15 Static Mixer 16 Separation Tank 17 Distributor 18 mixed liquid discharge pipe 19 automatic electric valve 20 external discharge pipe 21 circulation pump 22 treated water discharge pipe 23 sludge blanket layer

Claims (1)

[Claims] 1. A liquid / sludge separation tank, a mechanism for introducing a mixed liquid of drainage and a flocculant into the lower part of the separation tank, a treated water discharge mechanism provided above the separation tank, and the separation tank. Of the mixed liquid discharge mechanism provided approximately in the middle of
Wastewater treatment operation that connects approximately the middle and the bottom of the separation tank
A wastewater treatment device comprising a circulation pump which is operated during a stoppage period .