JP2001047079A - Method and apparatus for water treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably continue water treatment corresponding to a reaction advance state, in aerobically treating water containing an org. compd. with microorganisms, by controlling a treatment condition so that the amt. of carbon dioxide generated by microbial action and/or the amt. of oxygen consumed by microbial action becomes a predetermined range. SOLUTION: Raw water 14 containing an org. compd. is supplied to a treatment tank 12 through a raw water inflow line 9 by a raw water pump 3 to be aerobically treated with microorganisms and the treated water is discharged from a treated water outflow line 10. During this aerobic treatment, the concn. of oxygen obtained from an exhaust gas oxygen densitometer 4, the concn. of carbon dioxide obtained from an exhaust gas carbon dioxide densitometer 5, the pH of raw water in treated water obtained from the pH meter 6 of the treatment tank and the concn. of dissolved oxygen in raw water during treatment obtained from the dissolved oxygen densitometer 8 of the treatment tank are sent to a control device 13. In the control device 13, on the basis of these measured values, a blower 1 is controlled to perform the regulation of a supply amt. of oxygen and a stirrer 17 is controlled to regulate stirring intensity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for treating water containing organic compounds using aerobic microorganisms.

[0002]

2. Description of the Related Art In recent years, attention has been focused on wastewater treatment, particularly a method of treating wastewater containing organic substances using aerobic microorganisms. In this method, the processing load is likely to fluctuate depending on the state of microorganisms and the type and concentration of organic matter in the wastewater, and in order to perform efficient treatment, an appropriate index is found.
It is preferred to control the reaction. Thus, for example, in the activated sludge method, the amount of oxygen and nutrients supplied to the activated sludge tank is adjusted to control the reaction, and as an index at that time, MLSS (sludge amount) or MLSS (sludge amount) is used. SVI
(Sludge volume index) is used. However, these methods require a certain amount of time for measurement, so that real-time control is difficult, and there is a problem in terms of processing efficiency. It is also known to control the aeration amount using, for example, pH as a real-time control index (JP-A-56-33098, JP-A-58-12).
No. 4596), pH is not a direct index based on the action of microorganisms, and thus has a problem of low reliability and poor processing efficiency.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a water treatment method and a water treatment apparatus capable of performing efficient treatment in water treatment using aerobic microorganisms.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an aerobic treatment of water containing an organic compound using a microorganism, the amount of carbon dioxide produced by the action of the microorganism and / or the amount of the microorganism. The water treatment method is characterized in that the treatment conditions are controlled so that the amount of oxygen consumed by the action of (1) falls within a predetermined range.

[0005] Here, the step of supplying oxygen to the water being treated, the step of supplying nutrients to the water being treated to provide nutrients to the microorganisms, and the step of supplying oxygen to the water being treated to promote the decomposition of organic compounds by the microorganisms. It is preferable that the method further includes at least one step selected from the group consisting of a step of stirring water.

[0006] In addition, the amount of water to be treated
It is also preferable to select at least one selected from the group consisting of oxygen supply, nutrient supply and stirring intensity.

Further, when the amount of carbon dioxide generated by the action of microorganisms and / or the amount of oxygen consumed by the action of microorganisms is increasing, at least one selected from the group consisting of oxygen supply, nutrient supply and stirring intensity. One control amount is increased, and when the carbon dioxide amount and / or the oxygen amount is decreasing, at least one control amount selected from the group consisting of the oxygen supply amount, the nutrient supply amount, and the stirring intensity is decreased. It is also preferred.

[0008] Further, a treatment tank for treating water using microorganisms, measuring means for measuring the amount of carbon dioxide generated by the action of microorganisms and / or the amount of oxygen consumed by the action of microorganisms, and the measuring means are provided by the measuring means. A water treatment apparatus provided with a control means for controlling treatment conditions based on measured values is also preferable.

Water supply means for supplying water to be treated to the treatment tank; oxygen supply means for supplying oxygen to the water being treated;
It is also preferred that the composition further includes at least one means selected from the group consisting of a nutrient supply means for feeding the microorganisms and a stirring means for improving the oxygen supply efficiency.

[0010] It is also preferable that the control means is connected to at least one means selected from the group consisting of water supply means, oxygen supply means, nutrient supply means and stirring means.

Further, a method for producing treated water using the above-mentioned water treatment method or water treatment apparatus is also preferable.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention deals with water containing an organic compound (hereinafter referred to as organic waste water). This organic wastewater includes sewage and wastewater containing a large amount of specific substances discharged from factories, etc. Any water containing organic compounds should be applied as a treatment target. Can be. Further, as a method of aerobically treating water, for example, there is an activated sludge method, but in the present invention, in addition, when performing wastewater treatment using specific bacteria, or when performing microbial treatment of special wastewater Also, the present invention can be applied to a case where high-load wastewater is treated by highly efficient oxygen supply.

In the present invention, the treatment conditions are controlled so that the amount of carbon dioxide generated by the action of microorganisms and / or the amount of oxygen consumed by the action of microorganisms fall within a predetermined range. In water treatment using aerobic microorganisms, the microorganisms in the treatment tank decompose organic compounds in the raw water using oxygen, and mainly produce carbon dioxide and microbial cells. Therefore, if attention is paid to the point of consuming oxygen during decomposition and emitting carbon dioxide, the amount of carbon dioxide generated by the action of microorganisms and the amount of oxygen consumed by the action of microorganisms are measured, and these are measured within a predetermined range. By controlling the processing conditions so as to satisfy, efficient processing is possible. The amount of carbon dioxide generated by the action of microorganisms can be obtained, for example, by measuring the amount of carbon dioxide discharged from water during treatment or the amount of dissolved carbon dioxide in water during treatment. The amount of oxygen consumed by the action of microorganisms can be obtained, for example, by measuring the amount of oxygen discharged from water during treatment or the amount of dissolved oxygen in water during treatment. These measurements are
Each may be performed independently, for example, by simultaneously measuring the amount of carbon dioxide and the amount of oxygen emitted and controlling the processing conditions so that these are within a predetermined range, the stability of the processing increases, It is preferable because the processing can be performed efficiently.

In addition to the above, for example, it is also possible to measure the pH value or the like of raw water during treatment and control the treatment conditions so that the pH value falls within a predetermined range. When a plurality of measurement objects are used, the stability of the process is increased, but it may be appropriately selected as needed.

The control target of the processing condition is, for example,
The supply amount of water to be treated, the supply amount of oxygen, the addition amount of nutrients, and the stirring intensity can be mentioned. Specifically, when the amount of carbon dioxide generated by the action of microorganisms and / or the amount of oxygen consumed by the action of microorganisms is increasing, at least one selected from the group consisting of oxygen supply, nutrient supply and stirring intensity By increasing one control amount, processing corresponding to the increased load can be performed, and the stability of water treatment can be increased. In addition, when the amount of carbon dioxide and / or oxygen is reduced,
By reducing at least one of the above-mentioned control variables, a treatment corresponding to the load can be economically performed, and the stability of the water treatment can also be increased.

Further, when operating efficiently and stably with the treatment load of the water to be treated constant, the supply amount of the treatment water or the concentration and supply amount of the organic compound contained in the water to be treated. Is preferably within a certain range. When the concentration of the organic compound contained in the water to be treated is high, it is also preferable to supply the dilution water to the water to be treated and to control the supply amount.

Further, when the supply amount of the water to be treated is fixed and the treatment capacity is increased or decreased to perform an efficient stable treatment,
It is preferable to increase or decrease each of the control amounts such as the oxygen supply amount, the nutrient addition amount, and the stirring intensity alone or in combination. The control amount may be increased to increase the processing capacity, and the control amount may be decreased to decrease the processing capacity.

In addition, when the composition of the organic compound contained in the water to be treated changes, a method of controlling the amount of the sub-additive in accordance with the change in the composition can be used.

Further, when applied to the activated sludge method,
It is also preferable to control the amount of returned sludge.

The present invention is particularly effective for the treatment of organic wastewater containing waste water from weight reduction treatment of polyester fabric with caustic soda. The waste liquid often has a high BOD load, and the load greatly varies depending on the type of the target for weight reduction treatment. Conventionally, the waste liquid is diluted with other wastewater or the like and treated by the activated sludge method. However, since the treatment by the ordinary activated sludge method is performed while keeping the raw water inflow rate constant, in order to keep the quality of the treated water within a certain range, the treatment can be performed even when the highest BOD wastewater flows in. Thus, it is necessary to set processing conditions such as the amount of aeration. Therefore, in normal times, excessive processing conditions are set, resulting in poor efficiency.
The operation load of the treatment tank fluctuated greatly due to the concentration fluctuation of the raw water, and it was hard to say that the treatment stability was excellent. In the present invention, since the operating conditions are controlled by an index indicating a treatment state such as the amount of carbon dioxide generated by the action of microorganisms and the amount of oxygen consumed by the action of microorganisms, the above-described organic wastewater is also efficiently used. Water treatment can be performed stably.

[0021] The water treatment apparatus according to one embodiment of the present invention comprises:
As shown in FIG. 1, a treatment tank 12 for storing raw water 14,
A raw water pump (water supply means) 3 having a raw water inflow line 9 for supplying raw water to the processing tank 12, and a gas such as air supplied by the blower 1 is disposed at the bottom of the processing tank. A nutrient supply apparatus including a diffuser (oxygen supply means) 2, a stirrer (stirring means) 17 for finely crushing supplied gas bubbles to dissolve oxygen in raw water and improve oxygen supply efficiency, and a pump 15 (Nutrient supply means) 11
And a treated water outflow line 10 for taking out treated water, and an exhaust duct 16. The exhaust duct 16 is connected to an exhaust oximeter 4 for measuring the oxygen concentration of the gas flowing in the exhaust duct 16 and an exhaust carbon dioxide meter 5 for measuring the carbon dioxide concentration. In the processing tank 12,
A treatment tank pH meter 6 for measuring the pH of the raw water being treated and a treatment tank dissolved oxygen concentration meter 8 for measuring the dissolved oxygen concentration of the raw water being treated are provided. The above blower 1, raw water pump 3,
The pump 15 and the stirrer 17 are each electrically connected to the control device so that they can be controlled by a signal sent from the control device 13. The exhaust oxygen concentration meter 4, the exhaust carbon dioxide concentration meter 5, the treatment tank pH meter 6, and the treatment tank dissolved oxygen concentration meter 8 are controlled by control devices so that the measured values can be sent to the control device 13 as electric signals. Is electrically connected to

The raw water is supplied to the treatment tank 12 through the raw water inflow line 9 by the raw water pump 3, and after being subjected to aerobic treatment by microorganisms, is discharged from the treated water outflow line 10. During the aerobic treatment, the oxygen concentration (oxygen amount) obtained by the exhaust oxygen concentration meter 4, the carbon dioxide concentration (carbon dioxide amount) obtained by the exhaust carbon dioxide concentration meter 5, and the processing obtained by the treatment tank pH meter. Raw water pH, treatment tank dissolved oxygen concentration meter 8
The dissolved oxygen concentration of the raw water in the process obtained by the above is sent to the controller 13 as an electric signal, and based on these measured values, the blower 1 is controlled as necessary to adjust the oxygen supply amount. The agitator 17 is controlled to adjust the stirring intensity, the raw water pump 3 is controlled to adjust the amount of water to be treated, and the pump 15 is controlled to adjust the nutrient supply amount.

The control means includes, for example, an input unit for receiving the above-mentioned measured value, a memory unit for storing conditions for controlling each control object, and connected to the input unit and the memory unit. A configuration may be provided that includes a determination unit that compares and determines the measured value with the condition stored in the memory unit, and an output unit that outputs a control value for adjusting each control unit based on an output of the determination unit. The memory unit includes, for example, an increase / decrease rate of the amount of carbon dioxide generated by the action of microorganisms and the amount of oxygen consumed by the action of microorganisms, the amount of water to be treated, the supply amount of oxygen, the supply amount of nutrients, the stirring intensity, Can be stored, or the threshold value of the dissolved oxygen amount of the water during the treatment used when increasing the oxygen supply amount can be stored. In addition, by storing the relationship between the above-mentioned oxygen concentration change amount and carbon dioxide change amount and each control amount, for example, it is possible to perform control such that the oxygen concentration is constant, and to perform stable water treatment. be able to.

[0024]

(Example 1) Using a device having a tank capacity of 1 L as shown in FIG. 1, a mixed aqueous solution containing 5 g / L of disodium terephthalate and 1.9 g / L of ethylene glycol as a BOD source was used. Decomposition experiments were performed as raw water. Raw water was initially supplied at 200 mL / h (residence 5 h), and oxygen was supplied by aeration and stirring. In addition, inorganic salts (nutrition salts) were added so that BOD: N: P became 100: 5: 1. In operation, exhaust oxygen concentration is constant and DO is 1p
pm, the inflow of raw water and the amount of inorganic salt added were controlled. In addition, it confirmed beforehand that processability did not change in residence time between 5 to 9 hours.

When operating under the above conditions, when the BOD concentration of the raw water was increased 1.6 times, the raw water supply amount was 125 mL.
/ H. The BOD of the supernatant obtained by centrifuging the treated water and removing the cells was 3% of the raw water, which was equivalent to that before the concentration of the raw water was increased. (Example 2) Using the same apparatus as in Example 1, terephthalic acid disodium salt 8 g / L and ethylene glycol 3 g
A decomposition treatment experiment was performed using a mixed aqueous solution containing / L as a main BOD source as raw water. Raw water is 167 mL / h (retention 6h)
And oxygen was supplied by aeration and agitation. Further, an inorganic salt was added so that BOD: N: P became 100: 5: 1. In operation, the exhaust oxygen concentration was constant and DO was 1
The aeration rate and stirring intensity were controlled to be ppm.

During the operation under the above conditions, when the BOD concentration of the raw water was reduced by 1.6 times, the stirring intensity became 600 rpm.
m was controlled to 400 rpm, and power consumption required for stirring could be saved. (Example 3) Using the same apparatus as in Example 1, terephthalic acid disodium salt 8 g / L and ethylene glycol 3 g
A decomposition treatment experiment was performed using a mixed aqueous solution containing / L as a main BOD source as raw water. Raw water is 167 mL / h (residence 6h)
And oxygen was supplied by aeration and agitation. Further, an inorganic salt was added so that BOD: N: P became 100: 5: 1. In the operation, the oxygen supply was controlled so that the dissolved oxygen concentration, the exhaust oxygen concentration, and the exhaust carbon dioxide concentration were constant.

During operation under the above conditions, the dissolved oxygen meter was simulated in a failure state. However, from the information on the exhaust oxygen concentration and the exhaust carbon dioxide concentration, it was determined that the information on the dissolved oxygen concentration was incorrect, and the exhaust oxygen The oxygen supply amount was controlled based on the data of the concentration and the exhausted carbon dioxide concentration, and the treatment could be continued stably. Comparative Example 1 Using the same apparatus as in Example 1, terephthalic acid disodium salt 5 g / L and ethylene glycol 1.
A decomposition treatment experiment was performed using a mixed aqueous solution containing 9 g / L as a main BOD source as raw water. 200 mL / h of raw water (retention 5
h), and oxygen was supplied by aeration and stirring. Further, an inorganic salt was added so that BOD: N: P became 100: 5: 1. The operation was performed without controlling the conditions and fixing the inflow of raw water.

When operating under the above conditions, when the BOD concentration of the raw water was increased 1.6 times, the treated water was centrifuged and the BOD of the supernatant from which the cells were removed was 38% of the raw water, and the untreated raw water was 38%. Flowed out as treated water. (Comparative Example 2) Using the same apparatus as in Example 1, terephthalic acid disodium salt 8 g / L and ethylene glycol 3 g
A decomposition treatment experiment was performed using a mixed aqueous solution containing / L as a main BOD source as raw water. Raw water is 167 mL / h (retention 6h)
And oxygen was supplied by aeration and agitation. Further, an inorganic salt was added so that BOD: N: P became 100: 5: 1. The operation was performed under constant conditions without any condition control.

During the operation under the above conditions, the BOD concentration of the raw water was reduced by 0.6 times, but the oxygen supply was not controlled, so that the operation was continued at 600 rpm with stirring even if the raw water load was reduced. Power consumption was larger than that of No. 2. (Comparative Example 3) Using the same apparatus as in Example 1, terephthalic acid disodium salt 8 g / L and ethylene glycol 3 g
A decomposition treatment experiment was performed using a mixed aqueous solution containing / L as a main BOD source as raw water. Raw water is 167 mL / h (retention 6h)
And oxygen was supplied by aeration and agitation. Further, an inorganic salt was added so that BOD: N: P became 100: 5: 1. The operation was controlled in such a manner that the oxygen supply amount was determined only by the dissolved oxygen concentration.

When the dissolved oxygen meter was simulated during the operation under the above conditions, the control became impossible, and the process could not be continued.

[0031]

According to the present invention, the amount of carbon dioxide generated by the action of microorganisms and / or the amount of oxygen consumed by the action of microorganisms when aerobically treating water containing organic compounds using microorganisms is reduced. Since the processing conditions are controlled so as to be within a predetermined range, processing according to the progress of the reaction can be performed, and the processing can be stably continued.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a water treatment apparatus according to one embodiment of the present invention.

[Explanation of symbols]

 1: Blower 2: Air diffuser (oxygen supply means) 3: Raw water pump (water supply means) 4: Exhaust oxygen concentration meter 5: Exhaust carbon dioxide concentration meter 6: Treatment tank pH meter 7: Raw water inlet 8: Treatment tank Dissolved oxygen concentration meter 9: Raw water inflow line 10: Treated water outflow line 11: Nutrient supply unit (nutrient supply means) 12: Treatment tank 13: Control unit 14: Raw water 15: Pump 16: Exhaust duct 17: Stirrer (stirring) means)

Claims (8)

[Claims] 1. An aerobic treatment of water containing an organic compound using a microorganism, the amount of carbon dioxide generated by the action of the microorganism and / or the amount of oxygen consumed by the action of the microorganism fall within a predetermined range. Water treatment method characterized by controlling the treatment conditions as described above. 2. The step of supplying oxygen to the water being treated, the step of supplying nutrients to the water being treated to nourish the microorganisms, and the water being treated to promote the decomposition of organic compounds by the microorganisms. The water treatment method according to claim 1, further comprising at least one step selected from the group consisting of agitating the water. 3. The water treatment method according to claim 2, wherein at least one selected from the group consisting of an amount of water to be treated, an oxygen supply amount, a nutrient supply amount and a stirring intensity is selected as a control target. 4. When the amount of carbon dioxide generated by the action of microorganisms and / or the amount of oxygen consumed by the action of microorganisms is increasing, at least one selected from the group consisting of oxygen supply, nutrient supply and stirring intensity. One control amount is increased, and when the carbon dioxide amount and / or the oxygen amount is decreasing, at least one control amount selected from the group consisting of the oxygen supply amount, the nutrient supply amount, and the stirring intensity is decreased. The water treatment method according to claim 3. 5. A treatment tank for treating water using microorganisms, a measuring means for measuring the amount of carbon dioxide generated by the action of microorganisms and / or the amount of oxygen consumed by the action of microorganisms, and the measuring means. A water treatment apparatus, comprising: control means for controlling treatment conditions based on measured values. 6. A water supply means for supplying water to be treated to a treatment tank, an oxygen supply means for supplying oxygen to water being treated, a nutrient supply means for feeding nutrients to microorganisms, and for improving oxygen supply efficiency. The water treatment apparatus according to claim 5, further comprising at least one means selected from the group consisting of: 7. The water treatment apparatus according to claim 6, wherein the control means is connected to at least one means selected from the group consisting of water supply means, oxygen supply means, nutrient supply means and stirring means. 8. A method for producing treated water, comprising using the water treatment method according to any one of claims 1 to 4 or the water treatment apparatus according to any one of claims 5 to 7.