JPS625035B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a sewage treatment device that utilizes the action of aerobic microorganisms.

Sewage treatment that utilizes the action of aerobic microorganisms provides sufficient oxygen to the microorganisms that use the organic matter contained in the wastewater as a nutrient source, promoting their activity and oxidizing and decomposing pollutants. Various wastewater treatment methods and devices have been developed, such as , contact aeration methods, etc.

However, with conventional sewage treatment equipment, even if its functions functioned satisfactorily, it was difficult to stably obtain effluent water of good quality. However, in reality, the amount of sewage inflow, BOD load, etc. is almost never as planned, and it depends on the time of the day. Despite the fact that the load may fluctuate depending on the day of the week, season, etc., conventional equipment simply operates multiple pumps and blowers when there is a large amount of inflow sewage (overload) in response to such load fluctuations. However, because pumps and blowers were operated continuously even when there was little or almost no inflow sewage (underload), the nutrient-organism balance was disrupted, leading to decomposition phenomena, reducing the purification rate, and causing threads to deteriorate. This is because there was a problem in that the abnormal growth of bacteria caused a swelling phenomenon and reduced settling power.

This invention is intended to solve the above-mentioned problem, and makes it possible to adjust the aeration time and amount in response to changes in the load amount of inflow sewage and BOD load, thereby eliminating the disintegration and swelling of aerobic microorganisms. The object of the present invention is to provide a sewage treatment device that improves the purification rate and settling power and allows stable effluent of good quality to be obtained.

Next, the present invention will be described based on an embodiment shown in the accompanying drawings.

1 is an adjustment tank for storing wastewater discharged from a wastewater source (not shown), 2 is a measuring cell, 3 is an aeration tank, and 4 is a settling tank.

A plurality of pumps 5 and 6 (two pumps are shown in the figure, but more may be provided) are arranged in the adjustment tank 1 to pump wastewater into the measuring tank 2. It's getting old. The measuring tank 2 is used to adjust the amount of sewage flowing into the aeration tank 3, and depending on the device, such adjustment is made by the pump itself,
In some cases, weighing cell 2 is not installed. The aeration tank 3
, a plurality of blowers 7 (two blowers are shown in the figure, but it may be more than two blowers),
Air from the atmosphere can be supplied from the tank 8 through a discharge port 9 installed in the tank. This air supply is necessary to provide sufficient oxygen to the activated sludge, promote the reproduction of aerobic microorganisms, and activate their activities. Although only one aeration tank 3 is shown in the figure for convenience, two or more tanks are normally installed in series, and air can be supplied to each tank by blowers 7 and 8. In addition, this aeration tank 3
It may be one in which activated sludge is suspended, or it may be one in which a filter medium is arranged to allow living organisms to adhere. Sewage that has been sufficiently aerated in the aeration tank 3 is transferred from the upper part of the tank to a settling tank 4, where it is sedimented and separated, and the supernatant water is discharged after undergoing a post-treatment process as necessary. Since the settled sludge contains a large amount of aerobic microorganisms, it is returned to the aeration tank 3 via a return device 15. It is desirable that this return be carried out in the same way not only when the aeration tank 3 is one in which activated sludge is suspended, but also when contact aeration is used.

10 and 11 are float switches that operate the two pumps 5 and 6 placed in the adjustment tank 1;
One of the float switches 10 and 11 is located at a lower level of the adjustment tank 1, and when the inflowing sewage reaches the reference water level, it is turned on and switches on only the first pump 5, or the first and second pumps 5, 6 are operated alternately. The other pump 11 is located at a high place in the regulating tank 1, and is turned on to operate the second pump 6 when the inflowing sewage reaches an emergency water level, and at such an emergency water level, both pumps operate. . When the water level falls to the reference water level, only the second pump 6 stops, and when the water level falls below the reference water level, the first pump 5 also stops.

ON/OFF of the float switches 10 and 11
The signal is transmitted via the relay device 12 to the blower 7,
8. That is, when the lower float switch 10 is turned on, one or both of the blowers 7 and 8 are driven alternately, and when both float switches 10 and 11 are turned on, both the blowers 7 and 8 are driven simultaneously. .

Reference numeral 13 denotes an electronic timer, which is driven by the OFF signal of the float switches 10 and 11, and drives the blowers 7 and 8 for a fixed period of time even after the pump 5 or 6 has stopped. The reason why the electronic timer 13 performs this action is that the float switch operates the pump and starts sending wastewater to the aeration tank 3, and at the same time the blower operates and aerates. When both the pump and blower stop, the sewage that entered just before the blower stops will not be aerated, which is undesirable. Therefore, only the blower can continue to operate even after the pump stops. The extension time of this blower depends on how the electronic timer 13 is set, but it can be made longer or shorter depending on the amount of inflow of sewage and the amount of BOD load. In most cases, this setting time is satisfactory within 30 minutes to 1 hour.

A timer 14 operates the blower 7 or 8 separately from the float switches 10 and 11. The timer 14 has a built-in relay (not shown) and alternately operates one or both of the blowers 7 and 8 for a certain period of time. This is for operating only one blower continuously for 24 hours. In other words, when the load of inflowing sewage is small, if the blower is linked to the pump as described above, the blower will not operate unless the pump is operating, so in extreme cases, if there is no inflowing sewage all day long, the blower will operate all day. During this period, oxygen cannot be supplied to the activated sludge, which may cause the sludge to rot. To prevent this, the blower is turned on at regular intervals several times a day, even when the pump is not operating. I am trying to get it up and running. On the contrary, when it is necessary to promote the growth of aerobic microorganisms in the sludge, such as when there is a large amount of inflowing sewage or when the BOD load is large, it is necessary to keep one blower in operation at all times.

Next, we will discuss an example of the case where this device is applied to wastewater treatment discharged from a factory for processing animal bones and fish scraps.
This will be explained based on the diagram.

In this case, the operation of the pump and blower was set as follows.

(a) Lower float switch 10 in adjustment tank 1
(b) One blower 7 is operated simultaneously with the pump by the float switch, and the timer 1
4, the pump operates four times a day for one hour, and after the pump stops, the electronic timer 13
(c) The other blower 8 is set to operate 24 hours a day by a timer 14.

As a result of the above settings, the timer 14 is turned on from 2:00 a.m. to 3:00 a.m., and since the blower 7 is activated, two blowers are operated together with the blower 8, which operates 24 hours a day.
The inflow of sewage occurs three times: from 6:00 a.m. to 11:00 a.m., from 1:00 p.m. to 4:00 p.m., and from 7:00 p.m. to 11:00 p.m. Blower 7 is in operation during these times, resulting in two units in operation. Then, in the morning, this inflowing sewage stops and the float switch 10 turns OFF.
Electronic timer 13 at 11:00, 4:00 p.m., 11:00 p.m.
is activated, and the blower 7 is operated for an additional hour. According to this example, since the BOD of the sewage flowing into the aeration tank 3 is high, one blower 8 is always operated regardless of whether there is inflowing sewage or not, so that the necessary oxygen is sufficiently supplied. I'm trying to make it possible. Additionally, when wastewater is newly introduced by the pump, the other blowers are also activated so that two blowers can be put into operation immediately. By doing this, the balance between aerobic microorganisms and nutrients (organic matter) is easily maintained in the aeration tank, and the sludge does not disintegrate or expand, increasing the purification rate over a long period of time. Since we run two blowers when the inflow sewage is hot, the pH value is stable at around 7, which does not reduce the activity of aerobic microorganisms and increases the settling power. It is possible to make it work effectively.

Further, an example of a case where this device is applied to a place such as a housing complex or an inn where there is no inflow of sewage or only a very small amount of sewage depending on the time of day will be explained based on FIG.

In this case, the operation of the pump and blower was set as follows.

(a) Lower float switch 10 in adjustment tank 1
(b) One of the blowers 7 is set to operate simultaneously with the pumps by the float switch 10; (c) Both blowers 7 and 8 are set to 4 times a day by the timer 14. In addition to making it operate alternately,
After the pump is stopped, an electronic timer 13 is used to extend the operation for one hour.

As a result of the above settings, from 2:00 a.m. to 3:00 a.m., timer 1
4 enters and blower 7 operates to aerate, while
Float switch 10 is activated twice, from 6:00 a.m. to 11:00 a.m. and from 4:00 p.m. to 7:00 p.m., when the inflowing sewage reaches the standard water level.
When turned on, the pumps 5 or 6 operate alternately to flow wastewater into the aeration volume, and at the same time, the blower 7 operates. After the blower 7 stops pumping, the electronic timer 13 works to stop the blower 7 for an additional hour.
Note that during the time period from 4:00 pm to 9:00 pm, the float switch 10, electronic timer 13, and timer 14 operate in sequence, so the blower operates continuously. This example is a case of underload, and the aeration in the aeration tank is controlled by the float switch.
When turned on, the pump operates and the operation is performed only when inflowing sewage is hot to prevent excessive aeration, while the timer operates the blower intermittently during periods when there is no inflow of sewage for a long time. The minimum amount of aeration is repeated to prevent sludge from rotting. In addition, the blower, which operates in conjunction with the pump, uses an electronic timer to extend the time even after the pump stops, so that the sewage that enters the aeration tank just before the pump stops will not be aerated properly. I have to.

As described above, this invention can be applied even when the amount of sewage is large or the BOD load is high, or when the amount of sewage is concentrated depending on the time of day, season, etc.
Since the aeration conditions can be freely selected to correspond to any site conditions, such as those where water is almost completely depleted, it has the excellent effect of stably obtaining effluent water of good quality in any treatment facility at any site. It is something.

[Brief explanation of the drawing]

The figures show an embodiment of the invention, in which Fig. 1 is a schematic sectional view, Fig. 2 is a time chart of a pump and blower that cope with overload, and Fig. 3 shows a pump and blower that cope with underload. FIG. 1... Adjustment tank, 3... Aeration tank, 5, 6... Pump, 7, 8... Blower, 10, 11... Float switch, 13... Electronic timer, 14... Timer.

Claims (1)

[Claims] 1. In a sewage treatment device in which sewage flowing into a regulating tank is sent to an aeration tank via a pump, and air is supplied into the aeration tank by operating a blower to aerate the tank, a plurality of the pumps and blowers are installed. The pump and blower are linked to ON and OFF of the float switch in the adjustment tank, and
A sewage treatment device characterized in that each blower is configured so that it can be operated on a timer independently of ON/OFF of a float switch.