JPS6246477Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is an aeration circulation type in which sewage containing oxygen is forcedly circulated through a catalytic oxidation tower having a honeycomb tube filter bed carrying microorganisms. The present invention relates to an upward flow type biological catalytic oxidation device in which water flows upward.

Generally, in an aerated circulation type biological catalytic oxidation apparatus, wastewater is brought into a turbulent state and brought into contact with air to forcibly increase the amount of oxygen contained in the wastewater before being sent to a contact oxidation tower. However, if coarse air bubbles are allowed to enter the honeycomb tube filter bed along with sewage, when the air bubbles rise due to buoyancy, they will peel off the microbial layer attached to the honeycomb tube filter bed. The sewage is always supplied from the top of the contact oxidation tower, that is, above the honeycomb tube filter bed, and air bubbles are scattered near the water surface, so that only the sewage with dissolved oxygen is sent to the honeycomb tube filter bed. There is. Therefore, although conventional aerated circulation type biological catalytic oxidation equipment has advantages such as reliable separation of treated water from sludge, there are almost no examples of upflow type oxidation equipment. .

In addition, conventional aeration circulation type biological catalytic oxidation equipment
As mentioned above, the system relies solely on dissolved oxygen in wastewater to supply oxygen to microorganisms attached to the honeycomb tube filter bed. Therefore, the BOD concentration of wastewater is
If the concentration exceeds 200 ppm, the dissolved oxygen will be consumed as the sewage progresses along the length of the tube, and as no further oxygen can be supplied, the microorganisms will gradually become deficient in oxygen. It becomes impossible to maintain the activity of the honeycomb tube filter bed, and the characteristics of the honeycomb tube filter bed cannot be utilized, and it is practically impossible to make the depth of the honeycomb tube filter bed more than 1 m. For this reason, relatively shallow honeycomb tube filter beds must be arranged in parallel or in multiple stages, leading to an increase in the size of the device and a decrease in processing efficiency.

On the other hand, in order to increase the amount of dissolved oxygen in wastewater,
Various aeration methods have been proposed. For example, (1) a method that sprays wastewater radially while rotating high-speed rotating blades near the water surface, (2) a method that pressurizes with an injector and sprays wastewater onto the water surface, and (3) a method that forms an air lift chamber and sprays the wastewater onto the water surface. (4) A separate aeration tank is installed to aerate and remove air bubbles before introducing the wastewater to a honeycomb tube filter bed. but,
All aeration methods do nothing more than agitate the wastewater and increase the contact area with air, and are not only inefficient and not a fundamental solution, but also have the disadvantage that they tend to be bulky in terms of equipment. . This is partly due to the conventional basic idea that air bubbles must be easily dispersed and removed before wastewater enters the honeycomb tube filter bed.

The purpose of this invention is to fundamentally solve the above-mentioned conventional drawbacks, and to provide a simple aerated circulation type biological catalytic oxidation device that is an upward flow type and can employ a deep honeycomb tube filter bed. In particular, based on the knowledge obtained through research by the present inventors that the moderate detachment of the microbial layer by air bubbles actually promotes the activation of microbial metabolic activity when the air bubbles are small, air bubbles The major feature of this system is that the wastewater is supplied to the honeycomb tube filter bed by entraining fine air bubbles with the wastewater, breaking away from the conventional wisdom of avoiding the intrusion of water into the honeycomb tube filter bed as much as possible.

That is, the present invention provides a circulation system in which wastewater containing a large amount of oxygen is circulated through a contact oxidation tower filled with one or more stages of honeycomb tube filter beds carrying microorganisms, and the wastewater is purified by the oxidation action of the microorganisms. The system is of an upward flow type, and a plurality of rectangular plates twisted leftward and rightward are alternately inserted and fixed in the circulation piping flow path of this circulation system, so that the system has virtually no moving parts. Directly connected to a tubular line mixer capable of mixing air or oxygen into an emulsified state, and provided with means for introducing wastewater and means for introducing air or oxygen into the wastewater in a portion before entering the tubular line mixer, and further The air or oxygen after exiting the tubular line mixer is made into ultra-fine bubbles, and the piping flow path of the mixed wastewater in an emulsified state is branched, and each filter bed is connected to the bottom of the filter bed and the filter to flow upward in each filter bed. The present invention provides an upward flow aeration circulation type biological catalytic oxidation device characterized in that it is installed in communication with a bed gap.

Further, the present invention will be explained in detail using the drawings.

FIG. 1 is a flow sheet of the entire circulatory system showing one embodiment of the present invention. In the figure, reference numeral 1 denotes a contact oxidation tower, in which honeycomb tube filter beds 2 and 2' carrying microorganisms supported by supports 3 and 3' are arranged in series with a filter bed stage gap 4 in between. The wastewater introduced from the wastewater introduction pipe 7 passes through the tubular line mixer 5 which is supplied with air or oxygen from the air or oxygen introduction pipe 6. The tubular line mixer 5 has substantially no movable parts, and has a plurality of rectangular plates twisted leftward and rightward, each of which is alternately inserted and fixed in a spiral shape. By passing wastewater and air or oxygen through this tubular line mixer 5, the air or oxygen is made into ultrafine bubbles and mixed into the wastewater in an emulsified state.

As is clear from Fig. 1, the circulation system is of an upward flow type, and the wastewater mixed with air or oxygen in the form of fine particles by the tubular line mixer 5 is appropriately distributed by the branch valves 8' and 8. A portion of the honeycomb tube filter bed 2' in the contact oxidation tower 1 is branched out in small amounts, and some of it rises from the bottom of the filter bed below the honeycomb tube filter bed 2', comes into contact with microorganisms on the inner surface of the honeycomb tube filter bed 2', and undergoes a purifying action. It then reaches the filter bed stage gap 4. Furthermore, some
It is supplied to the filter bed gap 4 to be subjected to the purification action of microorganisms in the upper honeycomb tube filter bed 2. Here, it combines with the circulating water that has undergone the purification action in the previous stage and rises within the upper honeycomb tube filter bed 2, comes into contact with microorganisms and undergoes the purification action, and finally reaches the upper liquid level in the contact oxidation tower 1. The water reaches overflow and enters overflow gutter 12. Most of the water becomes circulating water again and the circulation pump 9
It is circulated in the circulation pipe 11 by. A portion is taken out of the system from the overflow gutter 12 via the treated water outlet 10.

Here, the waste water introduction pipe 7 is connected to the circulation pipe 11 as shown in FIG. The sludge contained in the sewage sinks and is extracted from the sludge extraction pipe 13.

In this way, by directly connecting the tubular line mixer to the sewage circulation piping flow path and introducing a small amount of air or oxygen to the circulating sewage in the circulation pipe before entering the tubular line mixer, the tubular line mixer can be activated. At the outlet, air or oxygen is mixed into the circulating wastewater in the form of ultrafine bubbles, resulting in an almost emulsified state. The circulating sewage that has passed through this tubular line mixer contains air or oxygen in the form of ultrafine emulsified bubbles along with dissolved oxygen, so the oxygen transfer efficiency to the circulating sewage is lower than that of conventional diffuser plate aeration. Even if dissolved oxygen is consumed by microorganisms while the wastewater passes through the honeycomb tube filter bed, the movement of oxygen from the ultrafine bubbles entrained in the wastewater is interrupted. Since this process is carried out without any problems, the utilization efficiency of the supplied air or oxygen is also greatly improved. Therefore, due to the synergistic effect of the dissolved oxygen contained in the circulating wastewater and the accompanying ultrafine emulsified bubbles of air or oxygen, oxygen deficiency problems in the microorganism layer are prevented and the honeycomb tube filter is The floor depth can be increased to 1 m or more, and long-term operation is possible. In addition, the tubular line mixer is simple and compact in terms of equipment, and it is only necessary to increase the lift of the circulation pump by 2 to 3 meters to make air or oxygen bubbles fine.
Moreover, since the amount of air or oxygen required is significantly reduced compared to the conventional method, the size of the blower and the like can be extremely reduced, which is extremely advantageous in terms of equipment and power costs. Furthermore, as in this example, two or more honeycomb tube filter beds are stacked and fixed in multiple stages with gaps between each stage, and air or oxygen is made into ultrafine bubbles, and the circulating wastewater mixed in an emulsified state is filtered. When the air or oxygen is dividedly supplied to at least one of the bottom of the bed and the gap between the filter bed stages and passed through the filter bed in an upward flow, the air or oxygen together with dissolved oxygen forms ultrafine bubbles for each filter bed stage. Since the mixed circulating wastewater is almost emulsified and is evenly distributed and supplied, the microorganisms in each filter bed are uniformly activated, and the death of microorganisms due to local inactivation is prevented. Therefore, the purification capacity of the entire honeycomb tube catalytic oxidation tower can be kept extremely high, and the installation area can be reduced, making it possible to create a compact wastewater purification device. It would be even more advantageous to use something like an ejector as a method for introducing air or oxygen into wastewater.

In the present invention, unlike conventional aerated circulation type biological contact oxidation equipment, air bubbles enter the honeycomb tube filter bed together with wastewater, but since the air bubbles are fine, this has a beneficial effect. In other words, it has the effect of creating moderate turbulence in the flow within each honeycomb tube due to the inclusion of fine air bubbles, which in turn promotes the activity of the microbial membrane that propagates through moderate metabolism, and also promotes the diffusion of oxygen to the microorganisms. is obtained. The effect of such fine air bubbles can be achieved by using an upward flow system, which allows uniform contact with the entire honeycomb tube filter bed, and allows the metabolized microbial layer fragments to adhere to air bubbles and float to the surface. It will be removed from the tower.

Example 1 In the flow sheet shown in Figure 1, a tubular line mixer with an inner diameter of 1/2 inch (2 elements) was used, and the honeycomb tube filter bed in the biological catalytic oxidation tower had a depth of 1000 mm per stage. They are stacked in two stages, and the circulating sewage is supplied partly under the second stage (at the bottom of the tower) and partly to the gap between the first and second stage filter beds. 30 as a circulation cycle
The test was carried out under conditions of cycles/hour. Compared to the BOD concentration of sewage of 210 ppm, the amount of air required to obtain treated water with a BOD concentration of 12 ppm was 35/hour.

Comparative Example 1 Using the same biological catalytic oxidation tower as in Example 1 in a downward flow type, the wastewater BOD was treated under the same conditions using an air lift and aeration tower equipped with a 2 m deep aeration pipe in the circulation system.
The amount of air required to reduce the concentration from 250 ppm to 15 ppm was 510/hour.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet of the entire circulatory system, each showing one embodiment of the present invention. 1: Catalytic oxidation tower, 2, 2': Honeycomb tube filter bed, 3, 3': Support stand, 4: Filter bed gap, 5:
Tubular line mixer, 6: Air or oxygen introduction pipe, 7: Sewage introduction pipe, 8, 8': Branch valve,
9: Circulation pump, 10: Treated water outlet, 11: Circulation pipe, 12: Overflow gutter, 13: Sludge extraction pipe.

Claims (1)

[Scope of utility model registration request] In a circulation system in which wastewater containing a large amount of oxygen is circulated through a contact oxidation tower filled with one or more stages of honeycomb tube filter beds carrying microorganisms, and the wastewater is purified by the oxidation action of microorganisms, the circulation system is an upflow type. Then, a plurality of rectangular plates twisted leftward and rightward are alternately inserted and fixed into the circulation piping flow path of this circulation system to create a system that has virtually no moving parts and emulsifies air or oxygen. A tubular line mixer is directly connected to the mixer, and before entering the tubular line mixer, means for introducing wastewater and means for introducing air or oxygen into the wastewater are provided. The remaining air or oxygen is made into ultra-fine bubbles, and the piping flow path of the mixed wastewater in an emulsified state is branched, and each is connected to the bottom of the filter bed and the gap between the filter bed stages in order to flow upward in each filter bed. This is an upflow aeration circulation type biological catalytic oxidation device that is characterized by being installed in