JPH04250898A - Batch-wise waste water treating device - Google Patents

Abstract

PURPOSE:To prevent the enlargement of the microorganism layers on contact materials by improving the aeration system of the batch-wise waste water treating device packed with the contact materials 3 in a treating tank 1. CONSTITUTION:A 1st air diffuser 4 which is so constituted that the ascending flow by bubbles for aeration comes into contact with the contact materials 3 and a 2nd air diffuser 5 which is so constituted that the descending flow by the bubble for aeration comes into contact with the contact materials 3 are provided. The air diffuser 4 and the air diffuser 5 are alternately operated. Since the ascending flow and the descending flow come into contact alternately with the contact materials 3, the surfaces of the contact materials 3 are washed and the aerobic and anaerobic microorganisms coexisting on the contact materials 3 affect each other to adequately suppress the activity. The dislodgment of the microorganism layers by the enlargement is, therefore, prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a batch-type wastewater treatment apparatus using a contact material.

0002

BACKGROUND OF THE INVENTION Some batch wastewater treatment apparatuses include a treatment tank filled with a contact material for supporting microorganisms. This contact material moderately suppresses the activity of microorganisms by allowing anaerobic microorganisms and aerobic microorganisms to co-propagate on the contact material, prevents overgrowth of microorganisms, and prevents the generation of large amounts of activated sludge. (For example, Japanese Patent Application No. 2-86176 filed by the present applicant)
(see issue). Further, an aeration means is provided in the processing tank, and in the aeration step, fine bubbles are discharged from the aeration means to promote the reaction.

0003

[Problem to be Solved by the Invention] In devices using a contact material as described above, when the aeration process is repeated, the layer of microorganisms attached to the contact material gradually becomes thicker, and the internal anaerobic membrane increases, causing a reaction. The problem arises that the process is delayed. There is also the problem that the thickened microbial layer tends to fall off, and when it falls off, the processing capacity decreases, requiring troublesome replacement.To prevent this, preventive measures such as cleaning at appropriate intervals are taken. I needed to.

[0004] The present invention has focused on these points, and has been made for the purpose of preventing the microbial layer on the contact material from enlarging by improving the aeration method.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the batch type wastewater treatment device of the present invention includes a first aeration means disposed so that an upward flow hits the contact material, and a contact material. and a second aeration means arranged so that the downward flow hits the air, and the first aeration means and the second aeration means are operated alternately.

[0006]

[Operation] When the first aeration means and the second aeration means are operated alternately, the contact material is alternately hit by an upward flow and a downward flow, so that the contact material is washed and the contact material is either aerobic or anaerobic. Microorganisms are prevented from increasing unilaterally, and the microorganism layer is also prevented from becoming so large that it becomes detached.

[0007]

[Embodiment] FIGS. 1 and 2 are schematic sectional views of an embodiment of the apparatus of the present invention, in which 1 is a treatment tank, 2 is waste water, 3 is a plurality of contact materials, and 4 is a first air diffuser. , 5 is a second air diffuser,
6 is a high-pressure air source for air supply such as a blower, and the air diffuser 4 is connected to the high-pressure air source 6 via a solenoid valve 7, and the air diffuser 5 is connected to the high-pressure air source 6 through a solenoid valve 8. Each contact material 3 has a structure in which, for example, a float and a microorganism support portion made of a fibrous material are integrated, and are provided in a state where they are submerged in the wastewater 2 at least during the aeration process. The filling rate of the microorganism support part made of material is 10
The dimensions are selected so as to have a numerical value of approximately 30% to 30%. Further, a plurality of contact materials 3 are arranged relatively densely to form a contact material group 10, and the intervals between each contact material group 10 are slightly wide.

The air diffuser 4 is arranged at the lower part of the contact material group 10, and the air diffuser 5 is arranged at the part where the contact material 3 is not arranged, that is, at the lower part between each contact material group 10. . Further, the solenoid valves 7 and 8 are turned on alternately at intervals of several minutes to several tens of minutes by a control unit (not shown), and accordingly, the aeration device 4 and the aeration device 5 are alternately turned on. Air bubbles are released. Note that other structures such as a support structure for the contact material 3, a waste water supply pipe, and a supernatant water drawing device are not shown.

The device of the embodiment is constructed as described above, and when the aeration device 4 is operated, an upward flow generated by the aeration bubbles released from the aeration device 4 is generated as shown by the arrow in FIG. It rises while hitting the contact material 3, and the downward flow passes between each contact material group 10 and descends. Furthermore, when the aeration device 5 is in operation, as shown by the arrow in FIG. descend.

[0010] In this way, the surface of the contact material 3 is washed by the alternating upward flow and downward flow, and the upward flow containing a large amount of oxygen and the downward flow containing a relatively small amount of oxygen alternately impinge on the contact material 3. Aerobic and anaerobic microorganisms coexist and propagate on the contact material 3, influence each other, and suppress their activity appropriately. For this reason, the microbial layer will not become so large that it will fall off, and either aerobic or anaerobic microorganisms will not increase unilaterally.

In this embodiment, the filling rate of the contact material 3 is selected to be approximately 10% to 30%. Note that the filling rate of the contact material means the volume ratio of the contact material to the volume of waste water in the treatment tank. In general, it is known that when the amount of contact material is small, an aerobic reaction progresses, and when the amount of contact material is large, microorganisms have less contact with oxygen, resulting in an anaerobic state. Aerobic reactions are necessary to lower oxygen demand (BOD), and aerobic reactions are promoted when the amount of contact material is small, so keeping the filling rate of contact material low is a countermeasure against BOD. is desirable. on the other hand,
In order to reduce total nitrogen (T-N), it is necessary to balance the contradictory reactions of nitrification reaction in aerobic conditions and denitrification reaction in anaerobic conditions. It is desirable to raise the value to some extent.

FIG. 3 shows a typical example of the results of research on this point by the present inventor. That is, using synthetic wastewater consisting of glucose, polypeptone, and potassium phosphate, the filling rate of the contact material was changed in a batch system with one cycle per day, and the filling rate and the reduction rate (or removal rate) of BOD and TN were determined. As shown in the figure, it was found that the BOD shows the highest value when the filling rate ranges from 0 to about 20%, and tends to gradually decrease when the filling rate exceeds 20%. Regarding TN, it was extremely low when the filling rate was 0%, and showed an increasing tendency up to around 20%, but a tendency to gradually decrease was observed when it exceeded around 20%. This indicates that if the filling rate is around 20% and lower than this, the anaerobic reaction will be insufficient, and if it is higher than this, the aerobic reaction will be insufficient.
This is thought to indicate that there is a good balance between aerobic and anaerobic reactions in the vicinity, resulting in the highest removal rate.

[0013] Therefore, the filling rate of the contact material is 10% to 30%.
%, preferably about 15% to 25%, good treatment results can be obtained for both BOD and TN, and there is also a synergistic effect with the improvement of the aeration method mentioned above. A good treatment reaction was carried out, and BOD and T-
It was possible to sufficiently reduce the N value. Note that the optimal value for the filling rate of the contact material varies depending on the treatment conditions and the type of wastewater, so as shown in Figure 3, it is 10% to 30%.
A range slightly wider than % is considered to be a selectable range.

[0014]

[Effects of the Invention] As is clear from the above explanation, the batch-type wastewater treatment apparatus of the present invention allows the upward flow and downward flow caused by the aeration means to alternately hit the contact material, thereby preventing the growth of the microbial layer. The thickness is automatically controlled to an appropriate value, and the microbial layer does not fall off due to enlargement, so there is no need for cleaning, etc., making management easier. In addition, by selecting the filling rate of the contact material to be approximately 10% to 30% as in the example, a good balance between aerobic and anaerobic reactions necessary for nitrogen removal is achieved, and the nitrogen removal rate is improved. is also possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the configuration of an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of the embodiment.

[Figure 3] Filling rate of contact material and biochemical oxygen demand (BO
It is a graph showing the relationship between the rate of decrease in D) and total nitrogen (TN).

[Explanation of symbols]

1 Processing tank 2 Wastewater 3 Contact material 4 First air diffuser 5 Second air diffuser 6 High pressure air source 7 Solenoid valve 8 Solenoid valve 10 Contact material group

Claims (1)

[Claims] Claim 1: A batch wastewater treatment device in which a treatment tank is filled with a contact material, the first aeration means being arranged so that an upward flow hits the contact material, and a first aeration means arranged so that a downward flow hits the contact material. 1. A batch type wastewater treatment apparatus, comprising: a second aeration means disposed in the second aeration means, and the first aeration means and the second aeration means are operated alternately.