JPS58193791A - Treatment of organic waste water - Google Patents

Abstract

PURPOSE:To prevent the generation of bulking and to maintain a high purification rate, by aerating a mixture of waste water and activated sludge in a preaeration tank to propagate activated sludge having a good settling property selectively thereby stabilizing the activated sludge treatment in an aeration settling tank. CONSTITUTION:Waste water is conducted into a preaeration tank 2, where the waste water is mixed with the activated sludge returned from an aeration settling tank 4 and is thus aerated. The activated sludge having a good settling property is thereby propagated. The mixture of the waste water and the activated sludge is transferred into the tank 4, and after the aeration, the activated sludge is settled and separated. The treated liquid is released and disposed through a pipeline 6. While the liquid mixed with the activated sludge in the tank 4 is returned to the tank 2, the sludge is agitated thoroughly by aerating the tanks 2, 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the treatment of wastewater by a batch activated sludge process.

The activated sludge method has many advantages such as low operating costs and excellent soaking of treated water, so it is widely adopted in the treatment of organic wastewater from various plants. Compared to the continuous activated sludge method, the batch-type activated sludge method requires fewer treatment tanks because the aeration tank serves as both the ritual and sedimentation rights, and the processing is simpler. , addition of wastewater, start of aeration, end of aeration, settling of sludge, start of discharge of treated water, etc. can be incorporated into a t-timer.
Because unmanned operation is possible, it is suitable for business establishments that operate during the day, such as many small and medium-sized factories, where it is difficult to provide labor and technology for operation management.
Its popularity is remarkable.

However, the biggest weakness of the activated sludge method is that it causes a phenomenon called bulking because it is difficult to artificially increase biological bone content. If the concentration of suspended solids in the treated water rises above the permissible limit, it becomes difficult to properly maintain the sludge concentration in the aeration tank, making it impossible to continue normal activated sludge treatment.

Most of the bulking is thought to be caused by the filamentous growth of Sphaerochilus fathom in the activated sludge and becoming the dominant species, but its occurrence is controlled by many factors. The reality is that there are still not enough preventive measures in place.

The present invention provides constant stability even under unmanned operation without causing bulking! The purpose of this project is to provide a wastewater treatment technology using a batch activated sludge method that can be carried out in the same manner as above. As a result of our research, we focused on the fact that activated sludge with extremely good settling properties can be obtained with very little waste water. aeration, precipitation, and discharge of supernatant water in an aeration and sedimentation tank [sequentially repeated batch activated sludge treatment 81
? The combination of this process and the process of returning part of the activated sludge mixture in the aeration and sedimentation tank to the pre-air tank is interesting.

Hereinafter, the present invention will be specifically explained based on the drawings.

In diagram IK1, wastewater is led through an inflow channel 1 to an air tank 2, where it is mixed with activated sludge and aerated. Supply of activated sludge A part of the activated sludge mixture in #i aerated and settled cypress 4 is returned to #1 air cypress 2 via a return path 7 by a return pump 8, and air is supplied from a blower 9. This is done by the pressure of a gas containing oxygen, such as air, sent through the pipe 10.

It is preferable that aeration be carried out at all times during drainage or inflow, and if the aeration is strong, the drainage and activated sludge should be sufficiently heated.
It is possible to match ff, and it is dissolved #! Elementary #IlI N1
WtL is something that can be maintained at 71 or higher.

Preliminary mt * The volume of the cypress 2 is usually f relative to the inflow amount of wastewater.
The NIIIiI#Wf period is set in the range of 10 minutes to 5 hours, but the growth effect of activated sludge with particularly good sedimentation properties is particularly reduced in the range of 30 minutes to 2 hours.

Next, the mixed ffI of wastewater and activated sludge is sent to the aeration-settling tank 4 via the pipe 3, or in the aeration-settling tank 4, it is sent to the aeration-settling tank 4 at the same time as the drainage starts to directly enter the homemade aeration tank 2, or in advance before or after that. From the set time, the blower 9jlliM111H
The aeration begins with the gas sent to the salmon, and continues for a certain period of time after the drainage of the wastewater ends, and then the aeration is stopped at t-1+, and the activated sludge is allowed to settle.

And 30 minutes to 5 hours a! After the settling time of the storm has passed, valve 5t is opened and treated water is discharged from pipe 6.
The treated water is normally discharged from pipe 6 and then sterilized by injection of salt or a tidal agent such as hypochlorite before being discharged, or it is freshly treated for further treatment at 716 degrees Celsius. Processing I! & sent to me.

Excess sludge is discharged into the sludge tank 13 by opening the valve 12 at the same time or before or after the release of the treated water from the aeration settling tank 4, and is either subjected to treatment such as dewatering or discharged for disposal by 11 m.

It is only necessary to operate the return pump 8 to return the activated sludge mixture in the aeration and sedimentation tank 4 to the preliminary aeration tank 2 while wastewater is flowing in. At other times, there is no particular landscape maintenance and the operation is reversed. When settling the KwI air-settled cypress 4 and discharging the treated water, return should be avoided as it will prevent the activated sludge from settling and deteriorate the treated water.

In order to keep the activated sludge 11Ml supplied to the pre-aeration tank 2 constant and to prevent the accumulation of activated sludge in the pre-aeration tank 2, the activated sludge mixture is returned.
It is preferable that the pre-aerated cypress 2 and the aeration settling tank 4 be aerated and the activated sludge mixture be sufficiently stirred.

The object of the present invention can be achieved if the activated sludge return amount is 5% or more of the wastewater inflow, and is particularly effective in the range of 10 to 100X.

It is preferable to use a return pump 8Fi, an air lift type which is less likely to crush activated sludge flocs, or it is also possible to use a mechanical type such as a spiral type.

To explain the operation time schedule of the treatment equipment implementing the present invention with reference to Fig. 2, in the figure, wastewater flows in for 10 hours from 8:00 to 18:00, and the preliminary In the aeration and sedimentation tank, aeration begins at 8:00, the same time that the haiku poets begin to flow in, and the warm air continues for 18 hours until 2:00 the next morning. Return pump 4 is operated from 8:00 a.m. until the next morning to return the activated sludge mixture. Activated sludge settled 111 minutes in 4 hours from 2:00 when aeration stopped to 6:01.
1kk included, then treated with clear water for 2 hours from 6:00 to 8:00 at 1! Release it as water, and at the same time discharge excess sludge.

The above operation 1- is repeated every day for 24 hours a day for t hours a day, and the drainage process is carried out automatically by controlling the start/stop or opening/closing timer of each pump, blower, and valve. It becomes possible.

In the present invention, in order to selectively proliferate activated sludge with good settling properties by multiplying activated sludge under the high V machine in the pre-aeration tank, batch-type activated sludge treatment in the aeration sink is extremely effective. According to the method of the present invention, high purification IXt can be achieved without causing bulking.
- Long xi! Not only can it be maintained stably over a period of
It is possible to effectively treat wastewater that is extremely prone to bulking because it contains a large amount of decomposable sugars, and its effects can be seen from the experimental examples described above.

Experimental Example 1 The synthetic wastewater shown in Table 1 was treated using a bench-scale experimental apparatus for the batch activated sludge method equipped with a pre-aeration tank with a capacity of 21 and an aeration-sedimentation tank with a capacity of 207. A processing experiment was carried out.

At this time, a conventional batch activated sludge process was also operated in parallel using an aeration sedimentation tank of the same shape and capacity as a comparison target. The conditions of this experiment were given to a second group of people, who were treated with 11klI for 30 days.
The results of M were shown to the third group. Note that the driving time-schedule & [as shown in Figure 3].

As is clear from the third party, in the 1-conventional method, the volume of activated sludge was as high as 8VI (sludge settling index II) or 260 ml 7y, and a large number of filamentous bacteria was detected, and the settling time of 4 hours was insufficient for activated sludge. However, with the method of the present invention, the 8V method was unable to perform 83 steps 1/
f, and almost no filamentous JllII was observed, and the treated water was rarely found to be good.

Margin 1st fit 2nd f below! 3rd Fitting Experiment-12 S* waste liquid from a certain pharmaceutical factory shown in No. 414 [As a treatment target, the same experimental eel weight as in Experimental Example 1 was used to conduct a comparative experiment between the present invention and the conventional method. This experimental condition is shown in the 5th blow.The treatment time schedule followed the 3rd diagram as in the experimental example.Activity used in the experiment? The generation of filamentous fungi was observed in the sludge UBV plant at 2001% l/l.
! Shown in Figure 4.

As is clear from the figure, in the present invention, the svr rapidly decreased from the beginning of the experiment, and the filamentous bacteria also decreased accordingly, and the expected IO day from the start of the treatment was 50 m1/fK1 for the 8v construction.
It decreased. On the other hand, in the conventional method, the PV construction
~180 WLI/7, showing some swelling tendency,
Many filamentous bacteria were also detected.

JII4 I Iris 5 table

[Brief explanation of the drawing]

! Figure 1 is a schematic diagram for explaining the present invention, Figure 2 is a diagram of the operation time and schedule of the processing equipment, Figure 3 is a diagram of the operation time and schedule in Experiment-1, and Figure @4 is a diagram of Experiment Example 2.
FIG. 8 is a chart of changes over time in 8VI. 1 inside, 2: preliminary aeration tank, 4: @air sedimentation tank, 7: i! , Feed route, 8: Anti-feed pump, 9: Blower, Anohito, patent attorney, Some
Hiroshi Tani

Claims (1)

[Claims] A process of mixing wastewater and activated sludge in a pre-aeration tank and aerating it, a process of releasing 4 atmospheres, sedimentation and supernatant water in an aeration-settling tank, then repeating batch-type activated sludge treatment, and aeration. A method for treating organic wastewater including a step of returning a part of the activated sludge mixture in a settling tank to a pre-treatment tank.