JP2003251109A - Moving bed type sand filter, moving bed type biological membrane sand filtering method and system therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-wasteful and stable moving bed type biological membrane sand filtering method. <P>SOLUTION: A moving bed type sand filter 1 is constituted so as to circulate filter media by utilizing an air lift 4 to wash them. The lost head of a filter bed 3, concretely, pressure P on a discharge side, a pressure difference between the upper and lower parts of the filter bed or the fluctuation of a water level is detected by using the moving bed type sand filter 1 to adjust the supply amount F of air to the air lift 4. An ascending flow moving bed type sand filter 1 is preferably used. The waste of energy required in operation can be omitted and the life of an apparatus, or the like, can be extended. This filter can be put to practical use in a moving bad type biological membrane sand filter. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving bed type sand filter utilizing an air lift (hereinafter, simply referred to as "moving bed filter" in the description of the present invention. The same applies to a moving bed type sand filtering method and system. A sewage treated water, human waste treated water, river water, industrial wastewater, waste landfill leachate, etc., as a target, and a moving bed filtration method for filtering and removing pollutants. A moving bed type biofilm sand filter utilizing an air lift (hereinafter, simply referred to as “moving bed membrane filter” in the description of the present invention. The same applies to the moving bed type biofilm sand filtration method and system). Using the same as above, targeting sewage, to remove the contaminants by filtration, at the same time to generate a microbial membrane on the sand surface of the filter medium, to the moving bed membrane filtration method of biologically decomposing and removing the contaminants

[0002]

2. Description of the Related Art A moving bed filter according to the present invention performs a filtering operation using the above-mentioned sewage as treated water while using an air lift to continuously circulate or reverse the sand or granules as a filter medium. Wash, separate pollutants from sand and regenerate filter media,
By circulating in the filtration bed, filtration and washing of the filter medium are simultaneously carried out to enable continuous filtration operation. As a typical model, there is an upflow moving bed sand filter, and there is also a horizontal moving bed sand filter.

As the moving bed membrane filter, a filter having substantially the same structure as that of the moving bed filter described above is used, except that sand or granules, which are filter media, are used as filter media and microorganisms capable of decomposing nitrogen compounds. It is used as a support, and continuous filtration of pollutants contained in water to be treated and biological decomposition and removal of nitrogen compounds are simultaneously carried out.

Regarding the above-mentioned upflow moving bed sand filter,
A brief description will be given with reference to FIG. 1 showing an example thereof. Figure 1
The moving bed type sand filter 1 illustrated in FIG. 2 has a cylindrical container having a funnel-shaped bottom as a filtration tank 2, and a filter bed 3 is formed by filling an appropriate amount of sand as a filter medium to form a filtration feed water 7 containing pollutants. Filter tank 2
Is supplied from the lower part of the above, and is passed through the filter bed 3 in the upward direction, that is, in the upward direction through the filter bed 3, solid contaminants are filtered and separated, and filtered water 8 is taken out by overflowing from the upper part. On the other hand, the air lift pipe 4 is inserted in the lower part of the filtration bed 3 to blow air 9. The sand of the filter medium is sucked by the air lift and is washed with air and water while rising in the air lift pipe 4 together with the air. A separator 5 is provided at the upper end of the air lift pipe 4 to separate the rising sand, the accompanying air, and the cleaning drainage.

The separated sand settles in the sand washer 6 together with pollutants. From the lower part of the sand washer 6, a part of the filtered water that has passed through the filter bed 3 is introduced as washing water and comes into countercurrent contact with the sand that forms an upward flow and sinks,
The sand and pollutants are separated and the sand is regenerated as a filter medium.
The reclaimed filter material is sent from the sand washer 6 to the filter bed 3
Settles on the surface of and is circulated to the filtration bed 3. The pollutants move upward in the sand washer 6 along with the upward water, and are discharged to the outside of the filter 1 as drainage 10 together with the washing drainage. In this way, the filter bed is constantly and quantitatively washed without switching between filtration and washing, so that the filtration bed is maintained at a certain level and the head loss is stable. The feature is that it is kept low.

[0006]

The operating conditions of the moving bed filter are generally those of the operating condition of the filter because at least the required level of filtered water can be stably obtained while keeping the condition of the filtering bed constant. Is set so that it is possible to clean the maximum load that is expected in order to provide a margin. Therefore, the filtration load of the treated water in the normal state is lower than the initially set condition, the amount of air blown into the air lift becomes unnecessarily large, and excessive circulation and cleaning are performed on the filter medium during most of the operating time. ing. As a result, it was found that wasteful energy was consumed and the wear of internal devices such as an air lift and the filter medium was promoted. On the other hand, if there is a load on the filtration bed that exceeds the set level due to excessive inflow of water to be treated, the problem of filtration failure due to breakthrough occurs. Even when a moving bed membrane filter is used in the membrane filtration process, it is considered that the same problems as described above will occur. The present invention has been completed to solve these problems.

[0007]

The present invention will be described with reference to the drawings. First, the present invention is characterized by using a moving bed type sand filter that circulates and cleans a filter medium using an air lift, and detects the fluctuation of the head loss of the filter bed to adjust the amount of air supplied to the air lift. A moving bed type sand filtration method is provided. An upflow moving bed sand filter can be preferably used as the moving bed sand filter. Then, a moving bed type sand filter that uses an air lift to circulate and wash the filter media, a detector that detects fluctuations in the head loss of the filtration bed, and the amount of air supplied to the air lift is adjusted based on the fluctuations in the head loss. The present invention provides a moving bed type sand filtration system, which is characterized in that it comprises an adjusting means for

Further, the present invention uses a moving bed type biological membrane sand filter which circulates and cleans a filter medium using an air lift, and detects the fluctuation of the head loss of the membrane filtration bed to determine the amount of air supplied to the air lift. A moving bed type biofilm filtration method characterized by adjusting. Then, a moving bed type biofilm sand filter that circulates and cleans the filter medium using an air lift, a detector that detects fluctuations in the head loss of the filter bed, and the amount of air supplied to the air lift based on fluctuations in the head loss A moving bed type biofilm sand filtration system is provided, which comprises:

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be specifically described with reference to FIG. FIG. 1 is a flow sheet showing an outline of a system, by way of example, in which the moving bed filtration method of the present invention and the system thereof are carried out using an upward flow moving bed filter. The moving bed membrane filtration system according to the present invention is almost the same as the flow sheet shown in FIG. 1, but the cleaning waste water 10 is circulated to the filtered supply water 7 as necessary to smoothly carry out the denitrification operation. It is possible to provide additional equipment specific to denitrification operation, such as a line for denitrification.

In the moving bed filter 1, unlike the filter of the alternating filtration / washing switching system, if it is within the maximum filtration amount of the filter to be used, it is separated by the amount of pollutants supplied and the washing of the filter medium, Since the amount of pollutants to be removed has almost reached the equilibrium and the filter bed 3 is kept in a constant state of operation, the increase of pollutants contained in the treated water 7 supplied to the filter bed 3 etc. As long as there is no particular variable factor in the load, the head loss of the filter bed 3 is kept constant regardless of the elapsed operating time. Utilizing this feature, the fluctuation of the head loss of the filtration bed 3, specifically, in the case of pumping the treated water, the discharge side pressure P of the raw water or the treated water feeding pump is set to the natural flow system. In this case, the water level or the pressure difference in the filtration bed can be directly monitored to detect the occurrence of load fluctuation in the filtration bed 3 from the fluctuation.

Prior to the practice of the present invention, the conditions under which the target water to be treated is filtered in advance to remove pollutants to obtain the required water quality, for example, the amount of water to be treated or the water quality is used as a parameter or variable. , Including the stability of the water quality, economic efficiency, etc.
It is recommended to incorporate it in the process control system (PC). In the moving bed type filter 1 which is operating with the air blowing amount in the optimum state, the increasing tendency of the pump discharge side pressure, the pressure difference or the water level usually shows the increasing tendency of the load of the filtering bed 3. In most cases, the reason why the load increases is that the cleaning of the filter medium cannot catch up with the amount of pollutant to be filtered, and pollutant accumulates on the filter bed 3 as compared with the case where the filter is kept in a clean filtration state, which tends to cause clogging. It depends. If left unattended, the filtration bed 3 may be blocked and may be inoperable. When the load fluctuation is detected, the air amount F blown into the air lift is adjusted to be the optimum amount based on the above relationship. Normally, when the load increases, the blown air amount F is increased to raise the cleaning ability of the filter medium.

On the contrary, the decrease in the discharge side pressure, the pressure difference or the water level usually indicates a decrease in the load of the filter bed, and indicates that the circulation amount of the filter medium and the amount of cleaning treatment tend to be excessive. . Therefore, wasteful energy consumption and the life of the filter medium and the filter are shortened, so that the amount of air is reduced and the cleaning treatment level of the filter medium is returned to an appropriate state. The means for adjusting the blown air amount is not particularly limited, and may be appropriately selected by controlling the rotational speed of the blower or by providing an air flow rate adjusting valve in the pipeline depending on the configuration of the filtering device.

The above moving bed filtration method and system thereof can also be effectively utilized as a moving bed membrane filtration method and system for simultaneously performing filtration and denitrification. In the case of the moving bed membrane filtration operation, in addition to the relationship between the load and the blown intake air amount in the above-described filtration operation, the relationship between the denitrification load and the blown air amount in the moving bed membrane filter is grasped in advance, It is advisable to incorporate it into the control system to achieve compatibility with the filtration operation. Generally, increasing the load in filtration operation may lead to inoperability, so the priority of setting the conditions is high, but responding to the excessive load of denitrification operation is to increase the residual nitrogen component in the treated water. However, the operation itself is unlikely to be disabled, and secondary means such as circulation of washing wastewater and supplementation of organic compounds are left, so it is only necessary to set the countermeasures in consideration of them.

[0014]

By utilizing the present invention, the moving bed filtration method and system can increase or decrease the amount of air blown into the air lift with respect to the increase or decrease of the load on the filtration bed to circulate the filter medium,
Since the cleaning amount can be appropriately increased / decreased, the operation without waste of energy can be performed and the life of the apparatus can be extended. In addition, in the filtration operation targeting the sewage treated water using the present invention, the energy used could be reduced by about 30% by the operation for 70 days.

The same effects as described above can be expected in the moving bed membrane filtration method and system.

[Brief description of drawings]

FIG. 1 is a schematic flow sheet showing an embodiment of the present invention.

[Explanation of symbols]

1: Upflow transfer bed type continuous sand filter 2: Filtration tank 3: Filtration bed 4: Air lift pipe 5: Separator 6: Sand washer 7: Filtration water supply 8: Filtration water 9: Air 10: Wash drainage F: Flow meter P: Pressure gauge

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C02F 3/34 101 B01D 29/08 510A ZAB 530C 540A F term (reference) 4D003 AA08 AB11 DA23 EA01 EA14 EA22 FA01 4D040 AA04 AA34 AA61 BB42 BB82 BB91 BB93

Claims (5)

[Claims] 1. A moving bed type sand filter that circulates and cleans a filter medium using an air lift is used to detect fluctuations in the head loss of the filtration bed and adjust the amount of air supplied to the air lift. Moving bed type sand filtration method. 2. The moving bed type sand filtration method according to claim 1, wherein an upflow moving bed type sand filter is used as the moving bed type sand filter. 3. A moving bed type biological membrane sand filter that circulates and cleans a filter medium using an air lift is used to detect the fluctuation of the head loss of the membrane filtration bed to adjust the amount of air supplied to the air lift. A moving bed type biofilm membrane filtration method characterized. 4. A moving bed type sand filter that circulates and cleans a filter medium using an air lift, a detector that detects fluctuations in the head loss of the filter bed, and the amount of air supplied to the air lift based on fluctuations in the head loss. A moving bed type sand filtration system comprising: 5. A moving bed type biofilm sand filter that circulates and cleans a filter medium using an air lift, a detector that detects fluctuations in the head loss of the filter bed, and a supply to the air lift based on fluctuations in the head loss. A moving bed type biofilm sand filtration system comprising: an adjusting means for adjusting the amount of air.