JPH04267986A - Flow rate change corresponding type waste water treatment apparatus - Google Patents

Abstract

PURPOSE:To continue filtration with low filtering resistance over a long period of time by performing filtration without exerting effect on the operation cycle of the suction filtering and suction stop of the filter module in an aeration tank even when the inflow amount of waste water to the aeration tank changes. CONSTITUTION:A plurality of filter module groups 2a, 2b, 2c are arranged in an aeratio tank 1 and opening and closing valves 5, 6, 7 are respectively provided to the treated water outflow pipes 5, 6, 7 connected to the filter module groups and the number of the opening and closing valves opened corresponding to the inflow amount of waste water to the aeration tank 1 is adjusted and the opening order of the opening and closing valves is altered successively.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a wastewater treatment device that biologically treats wastewater containing organic pollutants such as sewage, human waste, and industrial wastewater in an aeration tank, and also allows filtered water to be taken out using a filtration module. In particular, the present invention relates to a wastewater treatment device having the above-mentioned configuration that can cope with fluctuations in the amount of wastewater flowing into the aeration tank.

0002

[Prior Art] A method is already known in which a filtration module, especially a hollow fiber membrane module, is placed in an aeration tank for biologically treating wastewater containing organic pollutants, and the treated water is directly suction-filtered from within the aeration tank. (21st Water Pollution Society Conference Proceedings, p. 39). At this time, if the suction filtration is simply continued, clogging will occur, so by running the suction filtration in a cycle of repeating 5-minute operation and 5-minute stop, the hollow fiber membrane can be operated for a long time without cleaning. Attempts have been made to apply such technology to organic polluted water because it is possible to do so and the operation and management of the treatment equipment is easy.

0003

[Problem to be solved by the invention] It has been experimentally known that the filtration module can be operated for a long period of time without membrane cleaning by performing suction intermittently. It was largely unclear how the cycle could be set and how long the membrane life could be maintained. Normally, wastewater flows into the aeration tank continuously, so when the suction and suction stop, the amount of liquid in the aeration tank changes, the liquid level rises and falls, and the biological treatment in the aeration tank changes. conditions will also change, which will affect the filtration state when suction is restarted. Particularly when there are fluctuations in the amount of inflow of wastewater, if the suction filtration operation method is incorrect, the filtration resistance will rise sharply within a few days, making operation impossible.

[0004] The present invention has been made to improve and improve the problems of the conventional technology, and is capable of stable operation over a long period of time even when there are fluctuations in the amount of inflow of wastewater. The aim is to provide a wastewater treatment device.

[0005]

[Means for Solving the Problems] In order to improve the above-mentioned problems, the inventor of the present invention has conducted intensive studies by operating a filtration module for wastewater with fluctuations in flow rate over a long period of time, and has developed a system for using multiple filtration modules. We have discovered that long-term stable operation is possible by applying a water load as uniformly as possible to the membrane module, and by providing the membrane module with conditions that ensure a long suction stop time when suctioning at a high water volume. , has completed the present invention.

That is, the present invention has achieved the above object by the following means. In a wastewater treatment device in which at least two or more filtration modules having a filtration function are installed in an aeration tank for biologically treating wastewater containing organic pollutants and filtered by a pump and/or a head difference in water level,
The filtration module is divided into a plurality of filtration module groups each having one or more filtration modules, and each of the treated water outflow pipes from each filtration module group is provided with an on-off valve,
A wastewater treatment device capable of responding to flow rate fluctuations, characterized in that the number of opened on-off valves is adjusted according to the amount of wastewater flowing into an aeration tank, and the order in which the on-off valves are opened is sequentially changed.

Furthermore, in the processing apparatus of the present invention, the number of pumps that perform suction is controlled according to the number of opened on-off valves, or the number of rotations of the pumps is controlled, thereby reducing the amount of water applied to the filtration module. It is possible to make the load of the amount of filtered water as uniform as possible.

Furthermore, the above control can be performed by detecting the amount of inflow of wastewater at the water level in the aeration tank or at the level of a weir provided outside the aeration tank. As the filtration module used in the present invention, it is preferable to use one made of hollow fiber membranes. It is preferable to use a hollow fiber membrane made of polyethylene, polypropylene, etc.
For example, 5000 fibers are fixed together in a U-shape using a fixing member to form a hollow fiber membrane filtration module. The collection chamber of this filtration module is connected to a treated water outflow pipe, and one or more of the filtration modules are connected as a group to the treated water outflow pipe, and an on-off valve is installed in this treated water outflow pipe. In addition, a pump is provided, and by opening an on-off valve and driving the pump, filtered water is obtained by suction filtration with a filtration module. In this case, filtration can be performed by using a head difference in water level instead of using a pump, but since the amount of filtration (permeation flux) is small, it is preferable to use both methods in combination.

Two or more of the above filtration module groups are used. It is preferable that the amount of filtration by the entire filtration module corresponds to the amount of inflow of wastewater, but as mentioned above, it is better not to freely change the cycle of suction filtration and suction stop of the filtration module, so the amount of filtration by the entire filtration module should correspond to the amount of inflow of wastewater. Accordingly, the number of filtration module groups for performing suction filtration is increased or decreased by opening the on-off valve. In addition, for a filtration module group that enters a cycle in which suction should be stopped while performing suction filtration, the pump is stopped and the on-off valve is closed to stop the suction, and instead, the on-off valve of another filtration module group is opened. By driving the pump to perform suction filtration and changing the order in which the on-off valves are opened, treated water can be obtained continuously. Preferably, the opening and closing of the on-off valve is automatically controlled using a controller. The control can be performed by detecting fluctuations in the amount of wastewater flowing in using a water level detection device installed in the treatment tank.

0010

[Effect] When multiple filtration modules are installed in an aeration tank and suction is performed, if sludge adheres to one filtration module and the filtration resistance increases, the filtration amount of that filtration module decreases, and the filtration amount of that filtration module decreases. Less water load will increase on other filtration modules. At this time, as the water load increased, the compaction of the sludge adhering to the surface also increased, and during long-term operation, the adhering sludge became more likely to solidify on the filtration surface. It was found that when the sludge hardens, the filtration resistance increases further, and this propagates to the entire filtration module, resulting in a rapid increase in the filtration resistance of the entire suction filtration. On the other hand, it was found that even if sludge adhered, by stopping the suction, the adhered sludge could be peeled off due to the flow in the aeration tank, but it was also found that the more compacted the adhered sludge, the longer it took to peel off. Served. Based on these observation results, in order to operate the filtration module stably over a long period of time, it is important to prevent the effects of sludge adhesion and increased filtration resistance from propagating to other filtration modules as much as possible. During the suction operation, it is preferable to include a cycle that lengthens the suction stop time to prevent a sudden increase in filtration resistance and to enable stable operation over a long period of time. This type of operation is particularly effective when treating wastewater that fluctuates in water volume.

[0011]

[Examples] Hereinafter, the features and effects of the present invention will be specifically explained using examples. However, the present invention is not limited to this example. Example 1 FIGS. 1 and 2 show a wastewater treatment device which is an example of the present invention, with FIG. 1 showing a schematic front view of this treatment device, and FIG. 2 showing a schematic plan view thereof. In this treatment equipment, an aeration tank 1 with a capacity of 4 m3 is equipped with hollow fiber membrane filtration modules (12,000 membranes per membrane module, a membrane area of 10 m2,
Nine (2a in Figure 2)
,...4c), and as shown in Figure 2, each three pipes are made into a set, and the treated water outflow pipes 5, 6, and 7 are connected to each pipe. )8,
9, 10, and then pumps 11, 12, 1
3 was installed. In Fig. 2, the solenoid valve 8 is shown as "valve 8" due to space limitations.In the aeration tank 1, there is a level meter that can detect low water level LL, low water level L, medium water level M, and high water level H. 14 is installed, and this signal is sent to the controller 16 via a line 15, and from the controller 16 each solenoid valve 8, 9,
10 with line 17, and each pump 11, 12, 13 with line 1.
8, a signal was sent to open one solenoid valve at low water levels, two solenoid valves at medium water levels, and all (three) solenoid valves at high water levels. In addition, all solenoid valves were closed at low water levels. There is one pump at low water level, corresponding to the opening and closing of the upper solenoid valve.
Two pumps were operated at medium water level and three at high water level, but it is also possible to adjust the amount of filtered water by controlling the rotation speed with one pump. The inflow wastewater 19 enters the aeration tank 1, is suction-filtered as described above, and is taken out as treated water 20 from each treated water outflow pipe 5, 6, 7.

Using this treatment apparatus, domestic sewage was treated at a rate of 10 m3/day with the flow rate fluctuations shown in FIG. In FIG. 3, the horizontal axis represents the time of day, and the starting point is 6 o'clock in the morning to make it clear whether the flow rate increases or decreases. Fluctuations in inflow are shown as relative flow (vertical axis).

Run. In 1, the solenoid valve that opens at low water level is 8.
, fixed at 8 and 9 at medium water level, and operated for a long period of time. Ru
n. 2, for the first flow cycle, open valves 8 at low water level, 8, 9 at medium water level, 8, 9, 10 at high water level, then open valves 10 at low water level, 10, 9 at medium water level, and 10 at high water level. So 10,9,
Open 8, then 9 at low water level, 9, 10 at medium water level,
The operation was performed by opening high water levels 9, 10, and 8, and changing the order in which the valves were opened and closed in sequence. Run with a fixed solenoid valve to open. In No. 1, the filtration resistance increased from the first month after the start of operation, and then rapidly increased, making operation difficult. On the other hand, Ru
n. In No. 2, the value of filtration resistance was low even after two months after the start of operation, and stable operation was possible.

[0014] In some cases, the level meter 14 provided in the aeration tank 1 has a phenomenon in which the level detection malfunctions due to foaming. Therefore, an inflow weir was installed in the inflow water pipe,
When controlled at that level, stable control was achieved.

[0015]

[Effects of the Invention] In the present invention, even if the amount of wastewater entering the aeration tank fluctuates, by controlling the opening and closing of the on-off valves that operate multiple filtration module groups, the filtration operation method of each filtration module does not need to be changed. , it is possible to respond to fluctuations in the amount of inflow of wastewater and perform filtration for a long period of time with little filtration resistance.

By changing the number of filtration module groups to be used by opening and closing the on-off valves, and by changing the order in which the on-off valves open and close, there is little effect on the cycle of filtration and filtration stop of the filtration module groups. Furthermore, when the inflow rate is low, the rotation speed of the pump can be changed to maintain the filtration rate in accordance with the inflow rate.

[Brief explanation of the drawing]

FIG. 1 shows a schematic front view of a wastewater treatment device that is an example of the present invention.

FIG. 2 shows a schematic plan view of the wastewater treatment device shown in FIG. 1.

FIG. 3 shows a graph showing daily flow rate fluctuations of inflow wastewater in the wastewater treatment device in Example 1.

[Explanation of symbols]

1 Aeration tank 2a, 3a, 4a filtration module 2c, 3c filtration module 4b, 4c filtration module 5, 6, 7 Treated water outflow pipe 8,9,10 Solenoid valve 11, 12, 13 Pump 14 Level meter 15, 17, 18 lines 16 Controller 19 Inflow wastewater 20 Treated water

Claims (4)

[Claims] Claim 1: Wastewater that is filtered using a pump and/or water level head difference by installing at least two filtration modules each having a filtration function in an aeration tank that biologically treats wastewater containing organic pollutants. In the treatment equipment, the filtration module is divided into a plurality of filtration module groups each having one or more filtration modules, and an on-off valve is provided in each of the treated water outflow pipes from each filtration module group to control drainage to the aeration tank. A wastewater treatment device that responds to flow rate fluctuations, characterized in that the number of opened on-off valves is adjusted according to the inflow amount, and the order in which the on-off valves are opened is sequentially changed. 2. The wastewater treatment device according to claim 1, wherein the number of suction pumps is controlled according to the number of opened on-off valves, or the number of rotations of the pumps is further controlled. . 3. The wastewater treatment device responsive to flow rate fluctuations according to claim 1 or 2, wherein the amount of inflowing wastewater is detected at the water level in the aeration tank or at the level of a weir provided outside the aeration tank. 4. The wastewater treatment device responsive to flow rate fluctuations according to claim 1, wherein the filtration module is constructed from a hollow fiber membrane.