JP2001179009A - Moving bed type continuous sand filtering method and system therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively allow the treatment of backwashing wastewater to correspond to the concentration of a pollutant in raw water. SOLUTION: Backwashing wastewater discharged from a sand filtering apparatus is distributed by a moving bed type continuous sand filtering system having a solid removing device in its pretreatment stage and a part thereof is guided to the solid removing device and treated along with raw water to be allowed to meet with the remaining backwashing wastewater and this combined water is sent in a filter apparatus as filter supply water and the distribution amount of backwashing wastewater is controlled on the basis of the concentration of a solid in the filter supply water. Only a necessary amount of backwashing water is circulated to a solid treatment apparatus in the high- degree cleaning of sewage wastewater or domestic wastewater wherein biological treatment method and a flocculation and sedimentation treatment method is used jointly to perform rational and efficient operation to reduce treatment cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a continuous transfer type separation and removal method for separating and removing pollutants in advanced purification and reuse of effluent such as sewage drainage, domestic wastewater, and industrial wastewater, and pre-treatment of water and sewage. The present invention relates to a sand filtration method and a transfer type continuous sand filtration system.

[0002]

2. Description of the Related Art A transfer-type continuous sand filtration device to which the present invention is directed is to perform a filtration operation and at the same time, continuously backwash sand as a filter medium to separate pollutants from the sand. Is circulated through the filter bed to regenerate the filter medium and enable continuous filtration. The transfer type continuous sand filtration unit will be briefly described with reference to FIG. 1. A cylindrical container having a funnel-shaped bottom is used as a filtration tank 12, and an appropriate amount of filter medium sand is filled to form a filtration bed 13. Is supplied to the lower part of the filter tank 12 and passes through the filter bed 13 to be filtered, and the filtered water overflows from the upper part and is taken out. On the other hand, the sand of the filter medium is sucked by the air lift inserted into the lower portion of the filter bed 13 and washed with the air and water while rising in the air lift pipe 14 together with the air. A separator 15 is provided at the upper end of the air lift pipe 14 to separate the rising sand and the accompanying air. The separated sand settles on the sand washer 16 together with the pollutants.
From the lower part of the sand washer 16, a part of the filtered water that has passed through the filter bed is introduced, comes into an upward flow, comes into countercurrent contact with the settling sand, separates the sand and pollutants, and regenerates the sand as a filter medium. Let it. The sand that has been regenerated is sand washer 16
From the surface of the filter bed to form a filter bed 13. The contaminants move upward in the sand washer 16 together with the filtered water, and are discharged out of the filtration device 5 as backwash water.

[0003] The transfer type continuous sand filtration device 5 is usually provided with a solids removal device 2 for pretreatment to separate and remove a part of the pollutants in the raw water, and as filtration supply water from the filtration supply tank 3. , To the filtration device 5. The discharged backwash wastewater was sent to the solids removal device 2 and treated with raw water, and then sent to the filtration device 5 as filtration supply water.

[0004]

By the way, the backwashing amount of the filter medium is designed on the assumption of the maximum solid content contained in the filtered water, and the required backwashing amount is determined accordingly. Therefore, even when the solid content concentration in the filtered feed water to be treated is lower than expected, the designed amount of filtered water is used as backwash water, and the backwash wastewater is kept relatively clean, along with raw water. It had been treated by a solids removal device. In many cases, biological treatment is used in combination with the solids removing device, so that a large amount of backwash wastewater is treated, resulting in an increase in cost. The present invention provides the above-mentioned backwashing wastewater treatment method which is flexible to the solid concentration of raw water or filtered feedwater,
It is an object of the present invention to provide a rational transfer type continuous sand filtration system and a continuous sand filtration method that can respond effectively and reduce processing costs.

[0005]

According to a first aspect of the present invention, there is provided a solid material removing apparatus for removing impurities in raw water using a biological method and / or a physicochemical method. Then, in the transfer type continuous sand filtration method in which the obtained treated water is supplied as filtration feed water to the transfer type continuous sand filtration device to remove remaining impurities, the treated water is discharged from the transfer type sand filtration device. After distributing the backwash wastewater of the filter medium, one of which is led to the solid matter removing device to remove impurities together with the raw water, and then combined with the remaining backwash wastewater, and is fed to the continuous sand filtration device as a filtration supply water. A transfer type continuous sand filtration method characterized by feeding and controlling a distribution ratio of backwash wastewater based on a solid concentration in the filtration supply water.

According to a second aspect of the present invention, there is provided a solid substance removing device for removing impurities in raw water by using a biological method and / or a physicochemical method, and a filter for treating water treated by the solid substance removing apparatus. In a transfer type continuous sand filtration system comprising a transfer type continuous sand filtration device serving as feed water, a distribution device for distributing backwash drainage of filter media discharged from the transfer type sand filtration device, and a distributed backwash An SS removal piping system for guiding one of the wastewaters to the solids removal device supply side, a reflux water piping system for combining the remaining backwash wastewater with the treated water from the solids removal device to provide filtered supply water, A transfer type continuous sand filtration system provided with a distribution control device for controlling a distribution ratio of backwash wastewater based on a solid concentration in feedwater.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described with reference to the drawings and embodiments. FIG. 1 shows the flow of an embodiment of the present invention. In this example, the raw water supplied from the raw water supply pipe 1 to the solids removal device 2 is sent to the filtration supply tank 3 after the solids are removed. The solid matter removing device 2 includes a method of removing organic substances and inorganic substances as impurities in raw water by using a biological method and / or a physicochemical method. Generally, the activated sludge method and the coagulation method are used. Precipitation method and the like can be mentioned.

Next, the filtered feed water is sent to the lower part of the continuous-bed continuous sand filtration device 5, where the sand is filtered into a filter medium. Most of the filtered water overflows and is sent out of the system from the filtered water pipe 6, but part of the filtered water is used as backwash water for continuous regeneration of the filter medium and discharged from the continuous sand filtration device 5 as described above. The discharged backwash wastewater is led to a backwash wastewater distributor 8 through a backwash wastewater pipe 7. In the backwash drainage distribution device 8, the backwash wastewater is supplied to the SS removal piping system 9 for sending water to the solid matter removal device 2, and the return water is returned to the continuous sand filtration device 5 after being combined with the filtered supply water. The water is distributed to the flowing water piping system 10. As the backwash drainage distribution device 8, a control valve system, a distribution weir system, or the like can be appropriately selected and used.

The backwash wastewater sent to the SS removal piping system 9 is:
It is treated by the solids removing device 2 together with the raw water. This treated water merges with the backwash drainage sent to the reflux piping system 10 in the filtration supply water tank 3, is sent as filtration supply water to the continuous sand filtration device 5 through the filtration supply water pipe 4, and is filtered and filtered again. Becomes In this example, the filtration and supply water tank 3 is provided and merged. However, it is also possible to use a suitable tubular liquid mixer or to merge in a pipe or a water channel. In addition, as an embodiment of the present invention, a single-tank type continuous sand filtration device is illustrated in FIG. 1 as a transfer type continuous sand filtration device, but a multi-module type device can be similarly implemented.

Incidentally, the solids concentration in the backwash wastewater is naturally higher than the solids concentration in the raw water. Therefore, the solids concentration in the filtered feed water reaches or approaches the maximum solids content assumed at the time of design. In this case, the backwash wastewater having a high solid matter concentration flows into the reflux piping system 10, the solid matter concentration in the filtered feed water gradually increases and exceeds the maximum solid matter content, and the filtration device 5 is overloaded. And there is a possibility that the desired filtered water cannot be obtained. Therefore, in the present invention, the distribution control device 11 is provided, and the filtered supply water tank 3 in which the treated water from the solid content removing device 2 and the refluxed backwash wastewater are combined.
Alternatively, the solid matter concentration is measured in the filtered feed water pipe 4 or the water channel, and the backwash drainage distribution device 8 is adjusted and controlled based on the measured value so as not to exceed the maximum solid matter content. For example, when the solids concentration in the filtered feedwater reaches the designed maximum value, the amount of backwash wastewater distributed to the reflux piping system 10 becomes zero.

In the present invention, the pollutants once filtered and contained in the backwash wastewater are refined while being sent by a pump or the like, and are not trapped by the filtration device 5 but are filtered. It is inevitable that the quality of the water will be reduced. So, to solve this fear,
When the present invention was implemented using a solid matter removal device for biological treatment using the wastewater from a sewage treatment plant expected to use the present invention as raw water, the relatively soft pollution contained in biologically treated water was unexpectedly found. It has been found that the substance is trapped by the filtration device 5 without being miniaturized at all. No deterioration in the quality of the filtered water was observed by the practice of the present invention, confirming the feasibility of the present invention.

[0012]

EXAMPLES Wastewater from a sewage treatment plant of raw water was treated by an activated sludge method, and further filtered using a continuous sand filtration device of a transfer type, and the present invention was carried out for backwashing water for about two months. During this period, three conditions were set for the distribution ratio of the backwash water. FIG. 2 shows the processing result. It can be seen that the SS concentration in the filtered water is stable irrespective of the variation in the SS concentration in the filtered feed water.

[0013]

In the transfer type continuous sand filtration system utilizing the present invention, the operating load of the solids removal device is adjusted to correspond to the solids concentration in the filtered feed water, and indirectly the pollutant concentration in the raw water. Can be adjusted. Therefore, in many cases, in the advanced purification of sewage drainage and domestic wastewater that uses biological treatment in combination with a solids removal device, the solids treatment device does not process more than the required amount of backwash wastewater, and it is reasonable. By performing efficient operations, it is possible to reduce processing costs.

[0014]

[Brief description of the drawings]

FIG. 1 is a flow sheet according to an embodiment of the present invention.

FIG. 2 is a graph showing the results of an embodiment of the present invention.

[Explanation of symbols]

1: Raw water supply pipe 2: Solids removal device 3: Filtration supply water tank 4: Filtration supply water piping 5: Transfer type continuous sand filtration device 6: Filtration water pipe 7: Backwash drainage pipe 8: Backwash drainage distribution device 9: SS removal piping system 10: Reflux water piping system 11: Distribution control device 12: Filtration tank 13: Filtration bed 14: Air lift tube 15: Separator 16: Sand washer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01D 29/38 580Z

Claims (2)

[Claims] First, impurities in raw water are removed by a solids removing device using a biological method and / or a physicochemical method. In a moving bed continuous sand filtration method for removing remaining impurities by supplying the same to a sand filtering apparatus, a backwash drainage of a filter medium discharged from the moving bed sand filtering apparatus is distributed, and one of the backwash drains is used as the solid matter removing apparatus. After removing impurities together with the raw water, the wastewater is combined with the remaining backwash wastewater, fed into the continuous sand filtration device as filtered feedwater, and based on the solids concentration in the filtered feedwater, the backwash wastewater is discharged. Transfer type continuous sand filtration method, characterized by controlling the distribution ratio of water. 2. A solid substance removing apparatus for removing impurities in raw water by using a biological method and / or a physicochemical method, and a transfer bed using treated water treated by the solid substance removing apparatus as a filtration supply water. In a continuous bed sand filtration system comprising a continuous sand filtration system, a distribution device for distributing the backwash drainage of the filter medium discharged from the bed sand filtration device, and one of the distributed backwash wastewater is solidified. An SS removal piping system leading to the supply side of the material removal device, a return water piping system in which the remaining backwash wastewater is combined with the treated water from the solid matter removal device to obtain filtered supply water, and a solid concentration in the filtered supply water. A transfer type continuous sand filtration system, further comprising a distribution control device for controlling a distribution ratio of backwash wastewater based on the flow control.