JPH044096A - Method for controlling boundary of microorganism bed of upward current anaerobic treating tank for waste water - Google Patents

Abstract

PURPOSE:To eliminate the laboriousness of the manual analysis of a drawn sample by a sampling port and to allow the adequate execution of an automatic control operation by detecting the microorganism bed in a treating tank by a boundary meter of an oscillation system and automatically discharging granules by a motor driven valve interlocked to the boundary meter, thereby maintaining the height of the microorganism bed boundary within a specified range at all times. CONSTITUTION:The microorganism bed 4 in the treating tank 1 is detected by the boundary meter 9 of the oscillation system and the granules are discharged cooperatively with the detection to maintain the height of the microorganism bed boundary in the specified range at all times, by which the microorganism quantity is controlled. The immediate and accurate detection of the boundary of the microorganism bed maintained within the treating tank 1 without relaying on the manual analysis at the sampling port is executed in this way and the automatic control to discharge the excess granules is executed according to the results of the detection. The operation of the correct treating condition is thereby continued.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a wastewater treatment method for efficiently decomposing organic substances in industrial wastewater containing high organic concentrations such as sugars, starches, and distilled alcohol in an anaerobic manner. The present invention relates to a control method for maintaining proper operating conditions of an upflow anaerobic sludge blanket method (UASB method).

(Prior art) For anaerobic treatment of highly concentrated organic wastewater, starting from seed sludge in the slowly upward flow area of wastewater in a treatment tank, pelletized granules are formed by self-propagation of anaerobic microorganisms. The upflow anaerobic sludge blanket method is a method for contact treatment of upflow wastewater by holding granules in the form of a floating blanket near the lower layer of the upstream flow area to form a biological bed with a high concentration of anaerobic microorganisms. (UASB method).

In this method, after seed sludge has been introduced and operation has started, an inorganic powder carrier with a specific gravity of 2.0 or more, such as granulated slag, is added to promote granulation of anaerobic microorganisms into anaerobic wastewater. The treatment method was filed in Japanese Patent Application No. 1-23350.

In this upflow anaerobic wastewater treatment method using a powder carrier of granulated slag, there is a microbial bed in which granules with good sedimentation properties are gathered in an expanded bed shape in the treatment tank, and the upper part does not contain granules. Three regions are formed: a floating sludge plunget layer and a clarified solid-liquid separation section above it.

In reality, each layer is gently agitated by the gas generated from the lower layer, and the gas is accompanied by the solid, and each layer consists of three phases: liquid, solid, and gas, and the interface between each layer is not clearly defined.

In this treatment method, treatment efficiency can be improved by retaining as many granules and therefore microorganisms as possible in the treatment tank, but if there are too many granules and the sludge blanket enters the structure of the solid-liquid separation section, the quality of the treated water will deteriorate rapidly. becomes extremely aggravated. Therefore, in this anaerobic treatment, it is important to always maintain the amount of anaerobic microorganisms in the treatment tank at an appropriate value.

Conventionally, for this purpose, a large number of sampling ports are installed on the side of the treatment tank, and the sludge concentration of samples taken at each point is analyzed to determine the amount of microorganisms.

(Problems to be Solved by the Invention) However, in the prior art method of integrating the amount of sludge using a sampling port, analysis is cumbersome and time-consuming due to manual analysis, and as a result, automatic control that immediately responds to operating conditions cannot be performed.

In addition, in order to understand the amount of microorganisms, it is accurate and direct to detect the interface of the granule microorganism amount, and there are various interface detection meters such as turbidity measurement method using light absorption, ultrasonic wave, and capacitance method. In the upflow anaerobic treatment method, as mentioned above, the interface between each layer is not clearly separated and is fluid, so these methods can be applied to detect the interface between the solid-liquid separation section and the sludge blanket layer. However, it is difficult to apply to detecting the interface between the granule microbial bed and the sludge plunget layer, which is important for understanding the amount of microorganisms, and the detection results of the boundary may be inaccurate and insignificant.

The present invention aims to achieve operational control that optimally and smoothly progresses the treatment status in a treatment tank using an upward flow anaerobic treatment method for high-concentration organic wastewater. The problem to be solved is to ensure that the measurement results obtained by detecting the microbial bed interface are the most accurate, and thereby enable automatic control operation to be carried out appropriately.

(Means for Solving the Problems) In order to solve the above problems, the present invention detects the microbial bed in the treatment tank with a vibrating interface meter, and automatically removes sludge using an electric valve linked to the interface meter. The height of the microbial bed interface is controlled to always be within a certain range.

That is, the method for controlling the microbial bed interface in an upward flow anaerobic wastewater treatment tank of the present invention has an overall configuration in which the wastewater in the treatment tank is slowly upward flowed for anaerobic treatment of highly concentrated organic wastewater. Starting from seed sludge, a powdered carrier of granulated slag is added to form pellet-like granules through self-propagation of anaerobic microorganisms, and the granules are collected in the lower layer of the upper region of the treatment tank as a microbial bed. In the upflow anaerobic sludge blanket treatment method, which forms a sludge blanket tank in the middle layer and a solid-liquid separation section for three-phase separation of sludge, treated water, and gas in the upper layer, the microbial bed in the treatment tank is measured using a vibrating interface meter. The feature is that the amount of microorganisms is controlled by detecting the microorganisms and draining the granules in conjunction with the detection to keep the height of the microorganism bed interface within a certain range.

(Operation) Generally, the upflow anaerobic sludge plunget method (UASB
(method), the sludge blanket is difficult to form a clear interface with the underlying granule layer, but when a powdered carrier of water granulated slag is added, a microbial bed of heavier granules is formed in the lower layer, which is in an expanded state but does not form a clear interface with the middle layer. The interface with the sludge blanket layer without granules is shown.

When the detection part of the vibrating interface meter is installed above the planned interface of the microbial bed, the detection part, which vibrates at a constant frequency, is restrained by the microbial bed and the amplitude decreases, so if this is detected as an electrical signal, the microbial bed can be detected. interface can be constantly measured with fairly high accuracy.

By automatically draining the granules using an electric valve linked to this interface meter, it is possible to maintain an appropriate amount of microorganisms in the treatment tank at all times.

It is appropriate for the granulated slag added as a carrier to have a particle size in the range of 0.02 to 0.1 nm.If the particle size is smaller than 0.02 ni, it will take more than 3 months to form the granule, resulting in the formation of granules. If the particle size is larger than 0.1 mm, a high upward flow velocity is required, and the operating condition will also become unstable.

(Example) Hereinafter, the method of the present invention will be explained in more detail with reference to Examples.

(2) Implementation Method and Apparatus Example FIG. 1 shows an example of an apparatus for implementing the method of the present invention. In this device, a raw water pump (2) is installed at the bottom of the treatment tank (1).
) from highly concentrated organic wastewater and recycling pumps (3
) flows in, is divided into equal fractions, and flows slowly upward in the tank.

In the tank, starting from seed sludge, a powdered carrier of granulated slag is added, and a pellet-shaped granule is formed by self-propagation of anaerobic microorganisms, and the granule is added to the lower layer under the upward flow of the treatment tank (1). A microorganism bed (4) consisting of an expanded layer is formed, and a sludge blanket tank (5) is formed in the middle layer. The treated water that has been treated by contact with anaerobic microorganisms in the lower and middle layers enters the upper layer together with the gas generated here, but the upper layer is transferred to the solid-liquid separation section (6) for three-phase separation of sludge, treated water, and gas. The separated treated water is transported from the upper water level to the treated water (
7), a part of which is recycled as described above to adjust the upward flow rate in the treatment tank, and the gas flows into the gas system (8).
released from.

In order to carry out the method of the present invention, a vibrating interface meter (9) is installed, and the sensor (10) of the detection section of the interface meter is placed above the microorganism bed (4) through the guide vibe (11). , the signal is processed by the interface meter body (12) and sent to the electric valve (1) of the sludge removal system (14) via the operation line (13).
5).

II, Example 1 In order to confirm the effectiveness of the method for controlling the microbial bed interface of the present invention, the following test was conducted to determine the optimum particle size of the granulated slag of the powder carrier.

(II-1>Test conditions Test device: inner diameter 100nv, liquid level height 1, 0OOn
n, liquid retention amount 7.8! The column was used as a treatment tank.

Waste water: TOD approximately 5.00011 consisting of peptone and glucose! J// synthetic wastewater.

Powdered carrier: The following three types of particle sizes obtained by crushing granulated blast furnace slag in a mill and sifting it were tested.

Average particle size: A: 0.1ml, B: 0.04in,
C: 0.0111 Addition amount: Average treatment tank capacity 100.0
001g/).

Upward flow rate: Operate in the range of 0.5 to 2.0 m/hr.

(II-2>Test results (II-2-1) Granule formation carriers A and B
In this case, granules with a diameter of 1111 can be produced in 2 to 3 months.

A large number of carriers A and B gather together, and this serves as a core to form a granule. Support C retards the formation of granules.

(II-2-2) Bed expansion The state of expansion of the microbial bed formed after two months is shown in FIG. 2, with the ascending flow rate LV [i/hr] on the horizontal axis and the expansion rate on the vertical axis.

The beds using carriers A and B expanded by 20 to 30% at a rate of [V·1.01/hr].The method for controlling the microbial bed interface according to the present invention could be appropriately implemented.

Carrier C has a swelling rate of 40% or more and is in a slightly fluid state.
The present invention was difficult because there was a large possibility that microorganisms would leak out of the system.

(2) Example 2 A test was conducted to confirm the validity of the method for controlling the microbial bed interface using the vibrating interface meter of the present invention by comparing it with the results of the conventional sampling port analysis method.

(III-1) Implementation Conditions Test Apparatus: The treatment tank was a tank with an inner diameter of 500 nm, a tower height of 3550 mm, and a liquid holding capacity of 600 nm.

Wastewater Two food factory wastewater (TOD=2,000~4.
00011 (J//) Powder support #: 1 granulated slag with average particle size o, osim
00, OOOng//addition.

Seed sludge: Add 3.0OO1 (+//) of anaerobic digestion sludge.

Upward flow rate: LV = 0, operated at 5-2.0 m/hr.

Sludge concentration: sludge analysis at 5 locations at each height of the treatment tank
A ring opening is provided to measure the vSS concentration.

Microorganisms, floor: Vibrating interface sensor according to the present invention detects the interface by suspending it from the top and detecting the interface by the length of the cable.

(III-2>Implementation progress (III-2-1) Accuracy of the interfacial measurement method of the present invention In Figure 3, the number of days [weeks] of operation elapsed is plotted on the horizontal axis, and the microbial bed interface height [m
] is taken as the vertical axis, and the measurement result (a) by the vibrating interface sensor according to the present invention and the vSS of the sampling port sample
The results were compared with the result (b) obtained by concentration measurement.

There was no significant difference between the two, confirming that the detection results of the microbial bed interface according to the present invention are highly accurate.

(ll-2-2>Detection Concentration Granules formed using granulated slag as a carrier change the composition ratio of microorganisms and carrier as microorganisms multiply.

If this ratio is expressed as ν53/SS, it is from 0.05 to 0.6
Although the response concentration of the interface meter changes depending on the composition change, it is possible to detect the interface height without particularly adjusting the sensitivity of the interface meter. In addition, vSS for each week in Figure 3
The concentration is 4,500.6,000.8, respectively.
500.9.500.12.000 and 13. O(
1 (JIg/ /).

(Effects of the Invention) As described above, according to the present invention, in an upflow anaerobic wastewater treatment method by forming anaerobic microbial granules, the interface of the microbial bed maintained in the treatment tank can be detected without sampling or manual analysis. Immediate and accurate detection is possible, and automatic control to remove excess granule can be performed according to the detection results, allowing continued operation under appropriate processing conditions.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of a tank showing an example of an apparatus for carrying out the method of the present invention, and Fig. 2 shows the ascending flow rate on the horizontal axis and the bed expansion coefficient on the vertical axis, and shows the influence of granulated slag carriers of various particle sizes. The diagram shown in FIG. 3 is a diagram showing the number of days elapsed on the horizontal axis and the floor height on the vertical axis, and shows the detection results of the floor interface according to the present invention in comparison with the results obtained by sampling technique analysis. DESCRIPTION OF SYMBOLS 1... Treatment tank, 2... Raw water pump, 3... Recycling pump, 4... Microbial bed, 5... Sludge blanket layer, 6... Solid-liquid separation section, 7... Treatment water system,
8... Gas system, 9... Vibrating interface meter, 10... Sensor, 11... Guide pipe, 12... Interface meter body, 13... Operation line, 14... Sludge removal Series, 15...
・Electric valve. Interface meter body 0.6 1. O LV (m/hr) Figure 2 Elapsed days (weeks)

Claims (2)

[Claims] (1) For anaerobic treatment of highly concentrated organic wastewater, anaerobic microorganisms self-propagate starting from seed sludge in the slowly upward flow area of the wastewater in the treatment tank and adding a powdered carrier of granulated slag. Pellet-like granules are formed by granulation, and the microbial bed where the granules gather in the lower layer of the upper flow of the treatment tank, the sludge blanket layer in the middle layer, and the solid-liquid separation in the upper layer of sludge, treated water, and gas. In the upflow anaerobic sludge blanket treatment method that forms a separation zone, the microbial bed in the treatment tank is detected by a vibrating interface meter, and the granules are drained in conjunction with the detection to determine the height of the microbial bed interface. 1. A method for controlling a microbial bed interface in an upflow anaerobic wastewater treatment tank, characterized by controlling the amount of microorganisms by always keeping the amount within a certain range. (2) The microbial bed in the upflow anaerobic wastewater treatment tank of claim 1, in which granulated slag with a particle size of 0.02 to 0.1 mm is used as the granular carrier to clarify the microbial bed interface. How to control the interface.