JPH02149398A - Anaerobic water treatment apparatus - Google Patents

Abstract

PURPOSE:To contrive the increasing of the amount of methane generated and the decreasing of the amount of sludge by providing a pretreatment device wherein the sludge produced in an anaerobic reactor and an initial settling basin is dissolved in water and sent back into the anaerobic reactor. CONSTITUTION:By means of a pretreatment device, sludge in a initial settling basin 1 and an excessive sludge in an anaerobic reactor 2 are drawn out for mixing with a high pressured air, such mixture is solubilized at a temperature of 100-350 deg.C in a sludge treating reacting tower 11, the gas-liquid separation thereof is effected by a gas-liquid separator 15 and the liquid so separated is added to a supernatant liquid of the settling basin 1 and sent back together to the anaerobic reactor 2 as a treated water. By means of a control device 19, moreover, the quality of the liquid thus treated is measured and, according to the measured valve, the amount of the sludge and air is controlled. As a result, the amount of a methane generated can be increased and, at the same time, the amount of the sludge can be reduced.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an anaerobic water treatment device for treating organic wastewater such as sewage and industrial wastewater, and particularly to an anaerobic water treatment device for improving treatment efficiency. The present invention relates to an anaerobic water treatment device having a pretreatment device.

(Conventional technology) Until now, aerobic water treatment using aerobic microorganisms has been the mainstream in the treatment of sewage and industrial wastewater, but in recent years anaerobic water treatment, which can recover methane gas and generates less sludge, has become mainstream. Water treatment is attracting attention and its applications are expanding.

An example of a conventional anaerobic water treatment device is shown in FIG.

Figure 2 shows a fluidized bed type anaerobic water treatment system, which is advantageous for increasing the concentration of microorganisms and shortening treatment time. Organic wastewater such as sewage and industrial wastewater is first sent to settling tank 1. is,
The supernatant liquid from which the solid matter has been sedimented and separated is made to flow into the anaerobic reactor 2.

The anaerobic reactor 2 is filled with a carrier such as sand or ceramic with a particle size of about 0.1 to 1 nn+, and methane-fermenting bacteria are attached and fixed to this carrier, and the carrier on which the methane-fermenting bacteria are attached and fixed is fluidized. The wastewater is treated while maintaining the condition.

That is, organic matter in wastewater is anaerobically decomposed by methane-fermenting bacteria while moving through a fluidized bed made up of carriers in a fluidized state, producing fermentation gas containing carbon dioxide gas and methane gas as main components.

In this case, the amount of water supplied from the initial settling tank 1 is insufficient to form a fluidized bed, so the treated water in the circulation tank 3 where the treated water in the anaerobic reactor 2 is temporarily retained is pumped. 4 and returned to the anaerobic reactor 2, thereby forming a good fluidized bed.

Anaerobic water treatment equipment can not only effectively decompose organic matter in wastewater, but also use the generated methane gas to generate gas power, for example.

If anaerobic water treatment is continued, the methane-fermenting bacteria in the anaerobic reactor 2 will multiply and the bed height of the fluidized bed will gradually increase. Therefore, excess bacterial cells are extracted from the sludge drainage pipe 5 and the sludge is treated outside the system.

(Problem to be solved by the invention) Generally, anaerobic microorganisms can quickly decompose organic matter dissolved in water, but it takes a long time to process solid organic matter, or they cannot decompose it at all. It is known.

Therefore, in the anaerobic water treatment equipment, the supernatant water on the first settling tank, that is, the solids separated by sedimentation, is treated in the anaerobic reactor 2, and the sludge drawn from the first settling tank 1 and the sludge drawn from the anaerobic reactor 2 must be processed separately.

However, this sludge treatment is expensive, and disposal of the ultimately generated waste also poses problems, so there is a desire to reduce the amount of sludge.

That is, if sludge can also be treated in the anaerobic reactor 2, the amount of methane gas generated can be increased as well as the amount of sludge can be reduced, so the establishment of this technology is desired.

The present invention provides a rational method for increasing the amount of methane gas generated and reducing the amount of sludge by providing a pretreatment device that dissolves sludge generated from an anaerobic reactor and a primary settling tank in water and supplies it to the anaerobic reactor. The purpose of this project is to provide a anaerobic water treatment device with a high level of functionality.

[Structure of the invention]

(Means and Effects for Solving the Problems) The present invention provides sludge at a temperature of 100 to 350°C before the anaerobic reactor in order to solubilize the sludge generated in the initial settling tank and the anaerobic reactor. In addition to providing a sludge treatment reaction tower that solubilizes under sufficient pressure to maintain the liquid phase, the water quality of this treated water is measured, and the amount of sludge and air supplied to the sludge treatment reaction tower is determined based on the measured water quality. This is an anaerobic water treatment equipment equipped with a control means to control the oxygen in the air supplied to the sludge treatment reaction tower at a high temperature of 100 to 350°C and under sufficient pressure to maintain the liquid phase of the sludge. After the sludge is decomposed into soluble organic matter, it is sent to an anaerobic reactor for anaerobic treatment.

Therefore, not only can the amount of sludge to be extracted and treated outside the system be significantly reduced, but also the amount of methane gas generated in the anaerobic reactor can be significantly increased.

In addition, when decomposing sludge in a sludge treatment reaction tower, if the residence time is too long or the amount of air supplied is too large, the sludge will be decomposed to carbon dioxide, nitrogen gas, and water, and the amount of methane gas generated will decrease. Optimum treatment is possible by measuring the suspended solids concentration and organic matter concentration of the treated water in the treatment reaction tower with a water quality meter and controlling the amount of sludge and air supplied.

(Example) An example of the present invention is shown in FIG. The same parts as in FIG. 2 are given the same reference numerals.

In FIG. 1, sludge from the initial settling tank 1 and excess sludge from the anaerobic reactor 2 are stored in a sludge storage tank 6, and are further passed through a heat exchanger 9 via a pump 7 and an automatic on-off valve 8. After being heated by the heat exchanger 9, the heater 10
is heated and sent to the sludge treatment reaction tower 11.

Air is also sent to the waste water pipe between the automatic on-off valve 8 and the heat exchanger 9 via the pump 12 and the automatic on-off valve 13, and joins with the sludge from the sludge storage tank 6.

In addition, the outlet pipe 14 of the sludge treatment reaction tower 11 is connected to the gas-liquid separator 1.
5, and above the gas-liquid separator 15 is the exhaust gas pipe 1.
6 is provided, and a treated water pipe 17 is provided below, and the treated water pipe 17 is connected to the heat exchanger 9 and further connected to the anaerobic reactor 2 via a water quality measuring device 18.

In addition, 19 is an automatic opening/closing valve 8 according to the output of the water quality measuring device 18.
, 13.

With the above structure, the supernatant liquid of the initial settling tank 1 is sent to the anaerobic reactor 2 for treatment, and the treatment principle and operation are the same as those shown in FIG.

On the other hand, the sludge initially settled in the settling tank 1 is sent to a sludge storage tank 6, and further to this sludge storage tank 6 is an anaerobic reactor 2.
Excess sludge generated is also sent through the sludge drainage pipe 5.

The sludge in the sludge storage tank 6 is pressurized by the pump 7 and sent to the heat exchanger 9 through the automatic opening/closing valve 8.

At this time, the air pressurized by the pump 12 also passes through the automatic on-off valve 13 and flows into the heat exchanger 9 in a state where it is mixed with sludge from the sludge storage tank 6.

The sludge that has entered the heat exchanger 9 is transferred from the treated water pipe 17 to the heater 9.
The temperature is raised by the high-temperature treated water flowing into the tank.

The sludge heated in the heat exchanger 9 is further heated in the heater 14 to
The temperature is raised to 0 to 350°C and then supplied to the sludge treatment reaction tower 11.

In this case, since it is necessary to maintain the sludge in the liquid phase in the sludge treatment reaction tower 11, the pumps 7 and 12 are selected so as to be able to increase the pressure to the required pressure.

In the sludge treatment reaction tower 11, sludge kept in a liquid phase at a high temperature of 100 to 350°C is decomposed using oxygen in the supplied air and becomes soluble organic matter.

By solubilizing this sludge, the concentration of soluble organic matter in the treated liquid in the outlet pipe 14 of the sludge treatment reaction tower 11 increases, and further, this treated liquid is separated into liquid and gas in the gas-liquid separator 17, and the gas is disposed of as waste. The liquid is discharged from the exhaust gas pipe 16 as a gas, flows into the heat exchanger 9 through the treated water pipe 17, raises the temperature of the sludge from the sludge storage tank 6, and lowers the temperature of the treated water itself, causing the water quality measurement device to 18 and flows into the anaerobic reactor 2.

In other words, the treated water whose temperature has decreased in the heat exchanger 9 is checked for water quality by the water quality measuring device 18, and then transferred to the anaerobic reactor 2.
Then, it is anaerobically treated in the same way as the Jusumi water from the first settling tank 1 mentioned above.

In this way, since both the organic matter in the supernatant water from the initial settling tank 1 and the soluble organic matter solubilized from the sludge in the sludge treatment reaction tower 11 are treated simultaneously in the anaerobic reactor 2, they can be drawn out of the system. The amount of sludge to be treated can be significantly reduced, and the amount of methane gas generated can be significantly increased.

However, if the residence time in the sludge treatment reaction tower 11 is too long or the amount of air supplied is too large, the sludge will not only be solubilized but also further decomposed into carbon dioxide gas, nitrogen gas, water, and the like.

In this case, the amount of methane gas generated in the anaerobic reactor 2 is reduced, so in the present invention, the quality of the treated water is measured with the water quality meter 18, and the opening degree of the automatic on-off valves 8 and 9 is adjusted to remove the sludge. The amount of soluble organic matter in the treated water upon solubilization is made to be as large as possible.

As the water quality measuring device 18, a suspended solids concentration measuring device is used to confirm that the sludge has been solubilized, and if there is a large amount of suspended solids remaining, the opening degree of the automatic on-off valve 8 is reduced. The amount of sludge supplied to the sludge treatment reaction tower 11 is reduced, and the residence time of sludge in the sludge treatment reaction tower 11 is lengthened to promote solubilization.

Alternatively, it is possible to increase the opening degree of the on-off valve 13 to increase the amount of air to be supplied, thereby promoting solubilization, or it is also possible to promote solubilization by a combination of the two.

In addition, an organic matter concentration measuring device such as a TOC measuring device, an ultraviolet absorbance meter, or a COD measuring device is used as the water quality measuring device 18, and when the concentration of soluble organic matter is low, the opening degree of the automatic opening/closing valve 8 is increased to increase the residence time. It is possible to increase the amount of soluble organic matter by shortening the length or by reducing the opening degree of the automatic on-off valve 13 to reduce the amount of air supplied.

Furthermore, by measuring the sludge concentration and soluble organic matter concentration in the sludge storage tank 6, and predicting the organic matter concentration in the treated water in the sludge treatment reaction tower 11, and comparing the actual measured values and predicted values, It is also possible to perform various controls.

Furthermore, it is also possible to use both a suspended solids concentration meter and an organic matter concentration meter as the water quality meter 18 to achieve more optimal control of the sludge treatment apparatus.

Although the above explanation has been made in the case of a fluidized bed type anaerobic reactor, similar effects can be obtained in the case of a fixed bed type anaerobic reactor.

Further, instead of using the automatic on-off valves 8 and 13, a variable flow rate pump may be used, and oxygen gas may be used instead of air.

〔Effect of the invention〕

As explained above, according to the present invention, the sludge generated in the primary sedimentation tank and the anaerobic reactor is solubilized under high temperature and pressure in the sludge treatment reaction tower to form soluble organic matter, and this is combined with the supernatant water of the primary sedimentation tank. The sludge is treated in an anaerobic reactor, and the quality of the treated water in the sludge treatment reaction tower is measured to control the amount of sludge and air supplied to the sludge treatment reaction tower to optimal values, so that no sludge is discharged outside the system. Not only can the amount of sludge that must be disposed of by the anaerobic reactor be significantly reduced, but the amount of methane gas generated by the anaerobic reactor can also be significantly increased, resulting in a rational anaerobic water treatment device that can significantly reduce treatment energy. It will be done.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of an anaerobic water treatment device according to the present invention, and FIG. 2 is a system diagram showing an example of a conventional anaerobic water treatment device. 1... Initial settling tank 2... Anaerobic reactor 3.
...Circulation tank 4...Pump 5...Sludge drainage pipe 6...Sludge storage tank 7...Pump
8,13... Automatic opening/closing valve 9... Heat exchanger 1
0... Heater 11... Sludge treatment reaction tower 12...
Pump 14... Outlet piping 15... Gas-liquid separator 16... Exhaust gas piping 17... Treated water piping 1
8...Water quality measuring device 19...Control device agent
Patent Attorney Nori Chika Yuki Yamashita

Claims (1)

[Claims] In an anaerobic water treatment system that processes organic wastewater such as sewage and industrial wastewater in an anaerobic reactor, sludge from the initial settling tank and excess sludge from the anaerobic reactor are drawn out and mixed with high-pressure air, and then pumped into the sludge treatment reaction tower. A pretreatment device that solubilizes the water at a temperature of 100 to 350°C to separate gas and liquid, adds it to the supernatant water of the first precipitation tank as treated water, and sends it to the anaerobic reactor, and measures the quality of the treated water. An anaerobic water treatment device comprising a control means for controlling the amount of sludge and the amount of air according to measured values.