JPH04330996A - Anaerobic water treating device - Google Patents

Abstract

PURPOSE:To keep the amt. of bacteria in a reactor at a high concn. and to prevent the outflow of a carrier into treated water by maintaining the level of the fluidized bed of the carrier at a preset level. CONSTITUTION:The water treating device is provided with a reactor 3 having the fluidized bed 9a of a carrier deposited with anaerobes, a raw water pump 2 connected to the bottom of the reactor 3 and used for introducing waste water into the reactor 3 and a circulating pump 5 connected to the bottom of the reactor 3 and used for introducing a part of treated water into the reactor 3. A detector 6 is furnished in the reactor 3 to detect the level of the fluidized bed 9a of the carrier. An arithmetic controller 7 is furnished to output a flow rate control signal to the circulating pump 5 based on the level signal from the detector 7 and the flow rate signal from the raw water pump 2 so that the level of the fluidized bed 9a is controlled to a set level.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anaerobic water treatment apparatus for anaerobically treating wastewater such as sewage and industrial wastewater.

0002

BACKGROUND OF THE INVENTION Anaerobic water treatment methods using methane bacteria, which are anaerobic bacteria, have problems such as the slow decomposition rate of organic matter and the time it takes to treat wastewater. However, in order to solve this problem, a carrier with a size of about 0.1 to 1 mm to which anaerobic bacterial cells (methane bacteria) are attached is filled into the reactor, and the wastewater introduced from the bottom of the reactor is mixed with the carrier. A fluidized bed type anaerobic water treatment device has been proposed in which wastewater treatment is performed by fluidizing a carrier using circulating water treated by a reactor. This fluidized bed type anaerobic water treatment device is capable of attaching a large amount of bacterial cells to the carrier, so that good wastewater treatment is possible with a short residence time.

[0003] Such a fluidized bed type anaerobic water treatment equipment is
Since it takes several months for a large amount of bacterial cells to adhere to the surface of the carrier, the system must be operated at a low load during that time. On the other hand, after a large number of bacterial cells adhere to the carrier surface, the carrier particle size gradually increases and the density decreases.
The sedimentation rate decreases. As the sedimentation rate decreases, the level of the fluidized bed of carriers with bacterial bodies attached increases, and eventually the carriers with bacterial bodies attached flow out of the reactor together with the treated water, deteriorating the treated water. In order to prevent such carriers from flowing out, a stirrer or the like is placed inside the reactor to peel off the microbial cells from the surface of the carrier, or carriers with enlarged particle sizes and attached microbial cells are pulled out from the reactor.

0004

[Problems to be Solved by the Invention] However, using a stirrer to separate the bacterial cells from the carrier or to pull out the carrier to which the bacterial cells are attached from the reactor reduces the amount of bacterial cells in the reactor. As mentioned above, in anaerobic treatment, it is important to maintain a large amount of bacterial cells in the reactor in order to perform good wastewater treatment. Therefore, peeling off the bacterial cells from the carrier or excessively pulling out the carrier to which the bacterial cells are attached from the reactor will lead to deterioration of wastewater treatment.

[0005] The present invention was made in consideration of these problems, and it prevents the outflow of carriers, reduces the amount of peeling and pulling out of bacterial cells, increases the amount of bacterial cells in the reactor, and improves the efficiency of treated water. The purpose of the present invention is to provide an anaerobic water treatment device that can improve water quality.

[0006]

[Means for Solving the Problems] The present invention provides a reactor having a fluidized bed of carriers to which anaerobic bacterial cells are attached, and a raw water pump connected to the bottom of the reactor to flow wastewater into the reactor in an upward flow. and a circulation pump connected to the bottom of the reactor to flow a portion of the treated water treated by the reactor into the reactor in an upward flow, the fluidized bed level of the fluidized bed of the carrier being maintained in the reactor. A detector is provided for detection, and a flow rate control signal is output to the circulation pump so that the fluidized bed level of the carrier reaches a preset level based on the level signal from the detector and the flow rate signal from the raw water pump. This is an anaerobic water treatment device characterized by being equipped with an arithmetic and control device.

[0007]

[Operation] According to the present invention, the level of the fluidized bed of the carrier is detected by the detector, the level signal from the detector is output to the arithmetic and control device, and the flow rate signal from the raw water pump is output to the arithmetic and control device. , the arithmetic and control unit uses the level signal from the detector and the flow rate signal from the raw water pump to
The flow rate of the circulation pump is controlled so that the fluidized bed level of the carrier becomes a preset level.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of an anaerobic water treatment apparatus according to the present invention.

In FIG. 1, the anaerobic water treatment apparatus is equipped with a reactor 3 having a fluidized bed 9a inside thereof containing a carrier to which anaerobic bacteria are attached.
The upper side is a processing layer 9b. Also reactor 3
A raw water pump 2 is connected to the bottom of the reactor 3, which causes wastewater temporarily stored in the raw water tank 1 to flow upward into the reactor 3. Furthermore, the treated water overflowing from the upper part of the reactor 3 flows into the treated water tank 4. Further, a part of the treated water (circulated water) in the treatment tank 4 is caused to flow upward into the reactor 3 from the bottom of the reactor 3 by the circulation pump 5. The bacterial cells attached to the carrier in the reactor 3 are composed of a group of methane bacteria, and are designed to decompose organic matter in wastewater into methane and carbon dioxide via lower fatty acids.

A detector 6 is installed inside the reactor 3 to detect the level of the fluidized bed 9a of the carrier in the reactor 3, and an arithmetic and control unit 7 is connected to the detector 6. Furthermore, the raw water pump 2 is also connected to the arithmetic and control device 7. This arithmetic and control device 7 is configured to output a flow rate control signal to the circulation pump 5 based on the level signal from the detector 6 and the flow rate signal from the raw water pump 2. That is, wastewater from the raw water pump 2 and circulating water from the circulation pump 5 flow into the bottom of the reactor 3, and the sum of the flow rates of these wastewater and circulating water pushes up the carrier and forms the fluidized bed 9a.
maintains the level of Therefore, a flow rate control signal is output to the circulation pump 5 so that the sum of the flow rates of waste water and circulating water becomes a flow rate that maintains a preset level of the fluidized bed 9a.

Next, the operation of this embodiment having such a configuration will be explained.

[0012] After the wastewater is once stored in the raw water tank 1,
Raw water is introduced into the reactor 3 from the bottom by the pump 2 . The organic matter in the wastewater is then decomposed into methane and carbon dioxide through lower fatty acids by the bacteria (methane bacteria group) attached to the carrier and maintained at a high concentration. The purified treated water overflows from the upper part of the reactor 3 and is discharged through the treated water tank 4. Further, a part of the purified treated water becomes circulating water and is returned to the bottom of the reactor 3 by the circulation pump 5.

The fluidized bed level of the fluidized bed inside the reactor 3 is detected by a detector 6 at any time, and changes in the fluidized bed level are monitored by an arithmetic and control unit 7. Further, the arithmetic and control device 7 monitors changes in the flow rate based on the flow rate signal from the raw water pump 2. Here, the flow rate flowing into the reactor 3 is represented by the sum of the flow rates of waste water from the raw water pump 2 and circulating water from the circulation pump 5. Therefore, the arithmetic and control device 7 outputs a flow rate control signal to the circulation pump 5 to control it so that the sum of the flow rate of the circulation pump 5 and the flow rate of the raw water pump 2 becomes a flow rate that maintains the set fluidized bed level. do. In other words, when the amount of change in the fluidized bed level exceeds the set value, the circulation pump 5 is operated until the fluidized bed level reaches the preset value.
The arithmetic and control device 7 reduces the flow rate.

To explain in more detail the control of the circulation pump 5, the fluidized bed level is detected by the detector 6 that moves up and down inside the reactor 3 at regular intervals, and the arithmetic and control unit 7 detects the level of the fluidized bed.
The difference between the fluidized bed level for each hour and the preset fluidized bed level is determined. If this difference is a positive value and the absolute value exceeds a preset value, it is determined that the fluidized bed level has risen and there is a possibility of carrier outflow, and the arithmetic and control unit 7 controls the circulation pump 5. lower the flow rate. On the other hand, if this difference is a negative value and the absolute value exceeds a preset value, it is determined that the fluidized bed level falls below the set level and the carriers clump downward, resulting in a decrease in processing efficiency. The flow rate of the circulation pump 5 is increased by the arithmetic and control device 7. In this way, the fluidized bed level after adjusting the flow rate of the circulation pump 5 can be brought close to a preset level.

According to this embodiment, it is possible to prevent the carrier from flowing out from the reactor 3 and to reduce the amount of detachment of bacterial cells and the amount of carriers pulled out, so that the amount of bacterial cells in the reactor can be maintained at a high concentration. This makes it possible to improve the quality of treated water.

[0016] Since the set value of the fluidized bed level is determined by the growth rate of the bacterial cells, the flow characteristics of the reactor, the peeling characteristics of the bacterial cells, etc., it is desirable to determine it through preliminary experiments. Furthermore, since the present invention is applied to the fluidized bed reactor 3,
A certain amount of flow rate of the circulation pump 5 is required to maintain an appropriate flow state in the reactor. The lower limit of the flow rate of the circulation pump 5 is determined by the size and density of the carrier used and the flow characteristics of the reactor 3, but the circulation pump 5
The lower limit of the flow rate is determined.

[0017]

As explained above, according to the present invention, the fluidized bed level can be maintained at a preset level without peeling off the bacterial cells or pulling out the carrier to which the bacterial cells are attached. Therefore, the amount of bacterial cells in the reactor can be maintained at a high concentration, and the carrier can be prevented from flowing out into the treated water, and the quality of the treated water can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic system diagram showing an embodiment of an anaerobic water treatment apparatus according to the present invention.

[Explanation of symbols]

2 Raw water pump 3 Reactor 5 Circulation pump 6 Detector 7 Arithmetic control unit 9a Fluidized bed of carrier

Claims (1)

[Claims] 1. A reactor having a fluidized bed of carriers to which anaerobic bacterial cells are attached; a raw water pump connected to the bottom of the reactor for causing wastewater to flow upward into the reactor; and a raw water pump connected to the bottom of the reactor. a circulation pump for flowing a portion of the treated water treated by the reactor into the reactor in an upward flow; a detector for detecting a fluidized bed level of the fluidized bed of the carrier is provided in the reactor; A calculation and control device is provided that outputs a flow rate control signal to the circulation pump so that the fluidized bed level of the carrier reaches a preset level based on the level signal from the detector and the flow rate signal from the raw water pump. Features of anaerobic water treatment equipment.