JP2021013903A - Organic wastewater treatment method, and organic wastewater treatment device - Google Patents

Abstract

To provide an organic wastewater treatment method and an organic wastewater treatment device, capable of more efficiently keeping the temperature in an aerobic treatment device suitable for an aerobic treatment and of stably carrying out a wastewater treatment, by effectively utilizing heat generated in an aerobic treatment tank by supplying organic wastewater thereto.SOLUTION: The organic wastewater treatment method performed in an aerobic treatment device 1 aerobically and biologically treating one or more species of organic wastewater, includes controlling a supply flow rate of an organic wastewater being supplied into the aerobic treatment device 1 according to the calculation result of calculating a heat balance in the aerobic treatment device 1, taking the temperature of the organic wastewater, a heating value resulting from the BOD decomposition of the organic wastewater, a heating value resulting from the nitration of the organic wastewater, and a heating value resulting from operating the mechanical equipment of the aerobic treatment device 1 into consideration, so as to maintain the temperature in the aerobic treatment device 1 in a range of 15 to 40°C.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for treating organic wastewater and an apparatus for treating organic wastewater.

The activated sludge method is widely used as an aerobic biological treatment for sewage, human waste, organic wastewater discharged from food factories, and the like. Temperature conditions are an important parameter in operating activated sludge treatment.

When the inflow / drainage temperature is low, or when activated sludge treatment is performed in a cold region, it is necessary to adjust the heating of steam or the like. Especially in cold regions, if the operation is stopped when the outside temperature is low, the operation may be performed after adjusting the temperature during the restart operation after a long vacation such as the New Year holidays.

On the other hand, when the inflow effluent temperature is high, or when the high-concentration BOD concentration effluent having a BOD concentration of 5000 to 10000 mg / L or more is treated with activated sludge, aeration is caused by the bioreaction heat accompanying the BOD decomposition, although it depends on the effluent temperature. The temperature of the tank may become too high. Even in the nitrification / denitrification treatment in the human waste treatment, the water temperature in the nitrification tank / denitrification tank may become too high due to the heat of biological reaction and the Joule heat of the aeration device. Therefore, as a temperature adjustment measure, a cooling method using an outside-tank heat exchanger, a cooling method using an in-tank heat exchanger, a cooling method using a refrigerator, a cooling method using ground water, or the like is required.

A compost treatment can be mentioned as a treatment method using the heat of biological reaction. It is known that when organic waste is composted, the temperature inside the fermenter rises to 70 to 80 ° C. due to the heat of biological reaction in the primary fermentation stage.

As a method for treating organic wastewater using the heat of biological reaction, for example, the invention described in Patent Document 1 is known. In the invention described in Patent Document 1, the biologically treated water whose temperature has risen due to the heat of biological reaction in the urine treatment is used as a heat source for a heat pump, which is an external facility, and is used for temperature control, thereby saving energy as well as the purpose of water purification. It is stated that the conversion can be achieved.

Japanese Unexamined Patent Publication No. 58-95589

However, in the invention described in Patent Document 1, by supplying biologically treated water whose temperature has risen due to the heat of biological reaction to an external facility such as a heat pump, the device area becomes large and the facility becomes complicated. Further, in the invention described in Patent Document 1, periodic maintenance work of external equipment is also required. Therefore, it is also useful if a method and apparatus for heating or cooling the aerobic treatment apparatus more efficiently can be obtained by a method different from the invention described in Patent Document 1.

In view of the above problems, the present invention can effectively utilize the heat generated in the aerobic treatment tank by supplying the organic wastewater, and keeps the inside of the aerobic treatment apparatus at a temperature suitable for the aerobic treatment for stable wastewater treatment. Provided are a method and a treatment apparatus for treating organic wastewater capable of performing the above.

As a result of diligent studies by the present inventor in order to solve the above problems, the water temperature of the organic wastewater supplied to the aerobic treatment apparatus and the heat of biological reaction due to the decomposition of organic substances contained in the organic wastewater are favorable. It is effective to adjust the supply flow rate of organic wastewater supplied into the aerobic treatment device based on the heat balance in the aerobic treatment device, taking into consideration the calorific value associated with the operation of the mechanical equipment of the aerobic treatment device. I got the finding that there is.

The embodiment of the present invention completed based on the above findings is, in one aspect, in an aerobic treatment apparatus for aerobic biological treatment of one or more organic wastewaters, the water temperature of the organic wastewaters and the organic wastewater. Calculate the heat balance in the aerobic treatment device, taking into consideration the calorific value associated with BOD decomposition, the calorific value associated with the vitrification of organic wastewater, and the calorific value associated with the operation of the mechanical equipment of the aerobic treatment device. Organic wastewater, including adjusting the supply flow rate of the organic wastewater supplied into the aerobic treatment equipment so that the temperature in the aerobic treatment equipment is maintained at 15 to 40 ° C. based on the calculation result of It is a processing method of.

In one embodiment, the method for treating organic wastewater according to the embodiment of the present invention is to adjust the BOD concentration and the ammoniacal nitrogen concentration in the aerobic treatment apparatus by adjusting the supply flow rate of the organic wastewater. Including.

In another embodiment, the method for treating organic wastewater according to the embodiment of the present invention calculates the heat balance based on the following relational expressions (1) to (5) and puts it into the aerobic treatment apparatus. The method for treating organic wastewater according to claim 1 or 2, which comprises determining the supply flow rate of the organic wastewater to be supplied.
X1 (Kcal / d) = Supply flow rate (m ³ / d) x (Treatment water temperature (° C) -Supply water temperature (° C)) x 0.001 ... (1)
Y1 (Kcal / d) = Bioreaction heat A (Kcal / kg-BOD) per unit weight associated with BOD decomposition x amount of removed BOD (kg-BOD / d) ... (2)
Y2 (Kcal / d) = heat of biological reaction per unit weight associated with nitrification B (Kcal / kg-N) x NH _4- N vitrification amount (kg-N / d) ... (3)
Y3 (Kcal / d): Calorific value associated with the operation of mechanical equipment of the aerobic processing device ... (4)
X1 = (Y1 + Y2 + Y3) × α ・ ・ ・ (5)
(Α indicates the thermal diffusivity (-) from the aerobic treatment device)

In still another embodiment of the method for treating organic wastewater according to the embodiment of the present invention, the aerobic treatment device is a sprinkling filter, and the temperature inside the sprinkling filter is maintained at 30 to 40 ° C. Includes adjusting the supply flow rate of organic wastewater.

In still another embodiment of the method for treating organic wastewater according to the embodiment of the present invention, the volume ratio of gas to liquid (volume of liquid / volume of gas) β in the aerobic treatment device is 0.2 or less. Including being.

In still another embodiment, the method for treating organic wastewater according to the embodiment of the present invention includes that the BOD concentration of the organic wastewater supplied into the aerobic treatment apparatus is 1000 to 10000 mg / L.

In another aspect, an embodiment of the present invention is an aerobic treatment apparatus that treats one or more organic wastewaters with aerobic organisms, and generates heat due to the water temperature of the organic wastewater and the BOD decomposition of the organic wastewater. The heat balance in the aerobic treatment device was calculated in consideration of the amount, the calorific value associated with the vitrification of organic wastewater, and the calorific value associated with the operation of the mechanical equipment of the aerobic treatment device, and the calculation result of the heat balance calculation was obtained. Based on this, the treatment of organic wastewater is provided with a flow rate adjusting means for adjusting the supply flow rate of the organic wastewater supplied into the aerobic treatment device so that the temperature in the aerobic treatment device is maintained at 15 to 40 ° C. It is a device.

In one embodiment, the organic wastewater treatment apparatus according to the embodiment of the present invention includes a water temperature measuring means for measuring the water temperature of the organic wastewater and a diluting fluid for diluting the organic wastewater based on the measurement result of the water temperature. It is provided with a dilution ratio determining means for determining the dilution ratio of the waste water and a dilution fluid supply means for supplying the dilution fluid to the organic wastewater.

In another embodiment of the organic wastewater treatment apparatus according to the embodiment of the present invention, the aerobic treatment apparatus is a sprinkling filter, and the flow rate adjusting means is such that the temperature of the organic wastewater in the sprinkling filter is 30. Includes that the flow rate adjusting means adjusts the supply of organic wastewater so that it is adjusted to ~ 40 ° C.

According to the present invention, the heat generated in the aerobic treatment tank can be effectively utilized by supplying the organic wastewater, and the inside of the aerobic treatment apparatus is maintained at a temperature suitable for the aerobic treatment to perform stable wastewater treatment. It is possible to provide a method and a treatment apparatus for treating organic wastewater.

It is the schematic which shows an example of the organic wastewater treatment apparatus which concerns on embodiment of this invention. It is sectional drawing which shows the structural example of the film-like carrier of the sprinkling filter provided in the organic wastewater treatment apparatus which concerns on embodiment of this invention. It is a side view which shows the structural example of the film-like carrier of the sprinkling filter provided in the organic wastewater treatment apparatus which concerns on embodiment of this invention. It is a table showing the water temperature of high-concentration organic wastewater and the properties of low-concentration organic wastewater. It is a table showing the relationship between the inflow amount to the first-stage aerobic treatment apparatus of high-concentration organic wastewater and low-concentration organic wastewater, the inflow raw water BOD concentration, and the water temperature in the first-stage opportunity tank. It is a graph which shows the relationship between the inflow raw water BOD concentration, the water temperature in a reactor, and BOD treatment performance. When the flow rate of high-concentration organic wastewater is kept constant and the temperature of high-concentration organic wastewater is changed in the range of 30 to 15 ° C, the inflow amount of low-concentration organic wastewater is adjusted to optimize the BOD concentration of the inflow raw water. It is a graph which shows the change of the water temperature in a reactor at the time of this. It is a table which shows the property of the high-concentration organic wastewater and the low-concentration organic wastewater used in Example 2. It is a table showing the relationship between the amount of high-concentration organic wastewater, the amount of low-concentration organic wastewater, the inflow water BOD concentration, the water temperature in the reactor, and the generation status of butterfly flies.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention specifies the structure, arrangement, etc. of components as follows. It is not something to do.

(How to treat organic wastewater)
The method for treating organic waste according to the embodiment of the present invention is an aerobic treatment apparatus for aerobic biological treatment of one or more organic waste, in which the temperature of the organic waste and the BOD decomposition of the organic waste are decomposed. Calculate the heat balance calculation by calculating the heat balance in the aerobic treatment device, taking into consideration at least one of the calorific value and the calorific value associated with vitrification and the calorific value associated with the operation of the mechanical equipment of the aerobic treatment device. Based on the results, it involves adjusting the supply flow rate of organic wastewater supplied into the aerobic treatment apparatus so that the temperature in the aerobic treatment apparatus is maintained at 15-40 ° C.

As the organic wastewater, sewage, human waste and organic wastewater discharged from a food factory can be targeted. In particular, organic wastewater having a high organic matter concentration having a biochemical oxygen demand (BOD concentration) of 1000 mg / L or more, more preferably 5000 mg / L, still more preferably 10,000 mg / L or more is used as the organic wastewater according to the present embodiment. It can be preferably used.

As the aerobic treatment apparatus, an activated sludge apparatus, a sprinkling filter, a fluidized carrier method, a catalytic oxidation method, a biofilm filtration method, a rotary disk method and the like can be used. In particular, it is preferable to use an aerobic treatment device in which the volume ratio of gas to liquid (volume of liquid / volume of gas) β in the aerobic treatment device is 0.2 or less, more preferably 0.1 or less. ..

By using an aerobic treatment device with a volume ratio β of 0.2 or less, it is not necessary to consider the influence of the heat balance of the liquid phase other than organic wastewater, which is caused by the decomposition of organic substances contained in organic wastewater. The amount of heat of biological reaction can be estimated more appropriately and accurately. Examples of the aerobic treatment apparatus having a volume ratio β of 0.2 or less include a sprinkling filter bed and a rotating disk (gas phase portion).

If the BOD concentration and ammonia nitrogen (NH _4- N) concentration of the organic wastewater supplied into the aerobic treatment device are too high, the biological reaction heat generated in the aerobic treatment device causes the organic matter in the aerobic treatment device. The temperature of the wastewater becomes too high, which hinders biological activity and may require external equipment such as a cooling device. On the other hand, if the BOD concentration and the ammonia nitrogen concentration of the organic wastewater are too low, it becomes difficult to heat the organic wastewater by the heat of biological reaction generated in the aerobic treatment device, and an external facility such as a heating device may be required.

The BOD concentration of the organic waste water supplied into the aerobic treatment apparatus is preferably 1000 to 10000 mg / L, more preferably 2000 to 5000 mg / L, and further preferably 3000 to 4000 mg / L.

In the aerobic treatment apparatus, the heat of biological reaction is generated by the decomposition reaction of the organic matter contained in the organic wastewater by the aerobic biological treatment. In the present embodiment, the temperature inside the aerobic treatment device is adjusted to a suitable range by adjusting the supply flow rate of the organic matter contained in the organic waste water supplied into the aerobic treatment device, thereby decomposing the organic matter using microorganisms. The temperature is controlled to 15 to 40 ° C. suitable for the reaction. As a result, the heat generated in the aerobic treatment tank by supplying organic wastewater can be effectively utilized to maintain the inside of the aerobic treatment device at a temperature suitable for aerobic biological treatment by microorganisms, so that the equipment can be simplified. It will be possible to achieve stable wastewater treatment.

In order to properly control the reaction heat generated in the aerobic treatment equipment, the water temperature of the organic wastewater before aerobic biological treatment is measured, and based on the measurement result of the water temperature, a diluting fluid that dilutes the organic wastewater is used. By diluting, it is preferable to adjust the supply flow rate of the organic wastewater supplied into the aerobic treatment apparatus, specifically, the BOD concentration and the ammoniacal nitrogen concentration within a suitable range.

For example, when the water temperature of organic wastewater before aerobic biological treatment is too low due to the influence of outside temperature, etc., the biological activity of microorganisms in the aerobic treatment device is utilized by utilizing the biological reaction heat in the aerobic treatment device. In order to maintain the temperature condition, the concentration of organic matter in the organic wastewater, specifically, the BOD concentration and the ammonia nitrogen concentration are increased to obtain a large amount of heat of biological reaction in the aerobic treatment apparatus. As such, adjustments are made to increase the supply flow rate of organic wastewater.

On the contrary, if the water temperature of the organic wastewater before aerobic biological treatment is too high, the supply amount of organic wastewater may be reduced or the dilution ratio of the diluting fluid may be increased to increase the organic matter in the organic wastewater. Specifically, the BOD concentration and the ammoniacal nitrogen concentration are lowered, and the supply flow rate of the organic wastewater is adjusted so that the amount of heat of the biological reaction in the aerobic treatment apparatus can be kept small.

As the diluting fluid, a diluting fluid having a different water temperature, BOD concentration and / or ammoniacal nitrogen concentration from the organic wastewater (raw water) can be used. For example, water, river water, or the like may be used as the diluting fluid, or low organic wastewater or the like having a BOD concentration lower than that of raw water may be used. As the low organic wastewater, organic wastewater having a BOD concentration of less than 1000 mg / L, and more typically an organic wastewater having a BOD concentration of 500 mg / L or less can be used.

In order to adjust the supply flow rate of organic wastewater supplied into the aerobic treatment device to a suitable range, it is necessary to estimate the heat balance in consideration of the heat of biological reaction in the aerobic treatment device. Specifically, the temperature of organic wastewater (raw water) before aerobic biological treatment, the amount of heat generated by BOD decomposition of organic wastewater, the amount of heat generated by nitrification, and the heat generated by the operation of mechanical equipment of aerobic treatment equipment. It is preferable to calculate the heat balance in the aerobic treatment device taking at least the amount into consideration, and adjust the supply flow rate of the organic wastewater supplied into the aerobic treatment device based on the calculation result of the heat balance calculation. ..

Here, it is known that the heat of biological reaction per unit weight associated with the BOD decomposition of organic wastewater and the heat of biological reaction per unit weight associated with the nitrification treatment of ammoniacal nitrogen take constant values. In the present embodiment, the heat balance in the aerobic treatment apparatus is calculated by using the values of the heat of biological reaction per unit weight. For example, the heat of bioreaction per unit weight associated with BOD decomposition can be 3,000 to 5,000 Kcal / kg-removed BOD, and the heat of bioreaction associated with nitrification of ammoniacal nitrogen is 5,000 to 7,000 Kcal / Kg-removed N. Can be.

From the relationship between the amount of BOD decomposed in the aerobic treatment apparatus and the heat of biological reaction per unit weight associated with the BOD decomposition, the calorific value associated with the BOD decomposition of organic wastewater can be estimated. Similarly, the calorific value associated with the nitrification treatment can be estimated from the relationship between the amount of ammoniacal nitrogen nitrified in the aerobic treatment apparatus and the amount of heat of biological reaction per unit weight associated with the nitrification treatment of ammoniacal nitrogen. Similarly, the heat balance in the aerobic treatment can be calculated from the relationship between the water temperature of the organic wastewater before and after the aerobic treatment and the supply flow rate of the organic wastewater flowing into the aerobic treatment. By adjusting the supply flow rate of organic wastewater flowing into the aerobic treatment device based on these estimation results, the heat of biological reaction generated in the aerobic treatment device can be effectively utilized for heating or cooling. Installation of external equipment can be omitted.

More specifically, it is possible to calculate the heat balance based on the following relational expressions (1) to (5) and determine the supply flow rate of organic wastewater (raw water) to be supplied into the aerobic treatment apparatus. preferable.
X1 (Kcal / d) = Supply flow rate (m ³ / d) x (Treatment water temperature (° C) -Supply water temperature (° C)) x 0.001 ... (1)
Y1 (Kcal / d) = Bioreaction heat A (Kcal / kg-BOD) per unit weight associated with BOD decomposition x amount of removed BOD (kg-BOD / d) ... (2)
Y2 (Kcal / d) = heat of biological reaction per unit weight associated with nitrification B (Kcal / kg-N) x NH _4- N vitrification amount (kg-N / d) ... (3)
Y3 (Kcal / d): Calorific value associated with the operation of mechanical equipment of the aerobic processing device ... (4)
X1 = (Y1 + Y2 + Y3) × α ・ ・ ・ (5)
(Α indicates the thermal diffusivity (-) from the aerobic treatment device)

α indicates the thermal diffusivity (−) from the aerobic treatment apparatus, and is a coefficient determined based on the material of the reaction vessel of the aerobic treatment apparatus. When the reaction tank is made of steel plate (iron, stainless steel, etc.), it is a material having high thermal conductivity, so it is preferable to set the value of α in the range of 0.5 to 0.8. On the other hand, when the reaction tank is made of concrete or plastic material (vinyl chloride resin, acrylic tree species, etc.), it is a material with low thermal conductivity, so the value of α is 0.7 to 0 in concrete. 9. It is preferable to set the plastic material in the range of 0.8 to 1.0. The "treated water water temperature" indicates the water temperature after treatment in the aerobic treatment apparatus, and the "supply water water temperature" indicates the water temperature of the supply water supplied to the aerobic treatment apparatus.

The above equations (1) to (5) exemplify at least the conditions to be taken into consideration in the calculation of the heat balance in the aerobic processing apparatus, and in the actual calculation of the heat balance, the above (1) ~ Y1 to Y3, α to be incorporated into the calculation of equation (5) should be selected and omitted according to the processing conditions in the aerobic processing apparatus, taking into consideration all the conditions specified by equation (5). It is also possible to include other calorific values other than Y1 to Y3 and α in the calculation.

For example, as the heat of biological reaction generated in the aerobic treatment apparatus, for example, in the sprinkling filter method, a biofilm is formed on the surface of the filter medium, and the calorific value generated from the larva when the larva of the filter bed fly eats this as food. There is. In addition to the calorific value generated by the larvae, there is also the calorific value generated by insects involved in the food chain in the watering filter method. The calorific value including the exothermic heat generated by these microorganisms may be regarded as "the calorific value associated with other biological oxidation reactions (Y4)" and may be further taken into consideration in the calculation of the heat balance in the equation (5). That is, the right side of the above equation (5) may be set as "(Y1 + Y2 + Y3 + Y4) x α" and taken into consideration as one of the calorific values generated in the aerobic processing apparatus.

The bioreaction heat A (Kcal / kg-BOD) per unit weight associated with BOD decomposition and the bioreaction heat B (Kcal / kg-removal N) associated with the nitrification treatment of ammoniacal nitrogen are experimentally determined. Typically, the heat of biological reaction A can be 3000-5000 Kcal / kg-removal BOD, and the heat of biological reaction B can be 5000-7000 Kcal / kg-removal N.

In the aerobic treatment, when the BOD load is 2 kg / m ³ / d or more, the BOD treatment is the main component and the nitrification reaction of ammonia does not proceed, so the bioreaction heat Y1 due to BOD oxidation is the target. On the other hand, in the case of a low load of 1 kg / m ³ / d or less of BOD load, the ratio of Y2 increases in addition to Y1. Y4 can be considered in systems where the food chain is active in biological processing. For example, there is a case where the food chain is actively carried out in the biomembrane method such as the sprinkling filter method when the BOD volume load is low.

Further, regarding the equation (2), it is preferable to use the following two equations for the amount of removed BOD removed.
Amount of removed BOD (kg / d) = Amount of water (m ³ / d) x (raw water T-BOD (mg / L) -treated water T-BOD (mg / L)) x 0.001 ... (6)
Amount of removed BOD (kg / d) = Amount of water (m ³ / d) x (raw water T-BOD (mg / L) -treated water S-BOD (mg / L)) x 0.001 ... (7)
(Here, "T-BOD" indicates a BOD containing SS, and "S-BOD" indicates a soluble BOD (BOD of a solution filtered through a 1.0 μ filter paper).

In equation (2), equation (6) is usually used. On the other hand, when the biofilm is peeled off frequently due to the operating conditions (BOD load, etc.) in the biofilm method such as the watering filter method, the treated water SS concentration becomes high and the treated water T-BOD concentration also becomes high. In this case, the formula (7) may be used to calculate the amount of removed BOD.

In the case of activated sludge treatment, the “calorific value associated with the operation of mechanical equipment in the aerobic treatment tank” in equation (4) corresponds to the jule heat of the aeration device. For example, when the power of the aeration device and ^{0.8kw / m 3 / d, Y3} = 0.8 (kw / m 3 / d) × 24 (h / d) × 860 (kcal / kWh) = 16,512 ( It becomes Kcal / m ³ ). On the other hand, in the case of a sprinkling filter that does not use an aeration device, a circulation pump is used, but the temperature rise due to the circulation pump is a negligible value and does not need to be considered.

It is preferable to adjust the supply flow rate of the organic waste water supplied into the aerobic treatment apparatus so that the temperature in the aerobic treatment apparatus is maintained at 30 to 40 ° C., more preferably 33 to 38 ° C. For example, when a sprinkling filter is used as an aerobic treatment device, the generation of flies can be suppressed by maintaining the temperature of the sprinkling filter at 30 to 40 ° C, more preferably 33 to 38 ° C. , It is possible to perform stable wastewater treatment with less generation of pests.

Psychodidae, which normally occur in sprinkler beds, grow best under temperature conditions of 20 to 28 ° C, but grow poorly above 30 ° C. Therefore, when the sprinkling filter method is applied to the first-stage aerobic treatment when the sewage discharge or the like is roughly treated with BOD or when the aerobic treatment is performed in multiple stages, the temperature of the sprinkling filter is more preferably 30 to 40 ° C. By maintaining the temperature at 33 ° C to 38 ° C, the occurrence of flies can be suppressed. Usually, a chemical is used to exterminate Psychodidae, but by controlling under temperature conditions as in the present application, it is possible to perform stable wastewater treatment with less pests.

In cold regions where the outside air temperature of the aerobic treatment device is, for example, 10 ° C or less, when the operation of the aerobic treatment device is stopped for a certain period, for example, due to a regular inspection or a long vacation, during the operation stop period. The temperature inside the aerobic treatment device may drop, and a start-up operation may be required to stabilize the aerobic biological treatment when the operation is resumed.

In such a case, before stopping the operation of the aerobic treatment device for a certain period of time, the BOD load of the aerobic treatment device is made higher than the BOD load during normal operation for a predetermined period, and aerobic organisms in organic wastewater are used. Adjusting the supply flow rate of organic wastewater into the aerobic treatment equipment so that the temperature inside the aerobic treatment equipment is maintained at 15 to 40 ° C even during the outage period by the heat of biological reaction generated in the treatment. Is preferable. In addition, when organic wastewater is not produced for a certain period (5 days to 1 week), the temperature of the reaction tank is adjusted to 33 ° C. to 38 using a known high-concentration organic wastewater (BOD concentration 10,000 to 50,000 mg / L). Flies can be suppressed by adjusting the temperature to ℃.

When the outside temperature of the aerobic treatment device is high, such as in the summer, when the operation of the aerobic treatment device is stopped for a certain period due to inspection or long vacation, the temperature inside the aerobic treatment device is stopped during the operation stop period. May become too high and biological activity may be inhibited. In such a situation, the BOD load of the aerobic treatment device is made lower than the BOD load during normal operation for a predetermined period before the operation is stopped, and the biological reaction that occurs in the aerobic biological treatment of organic wastewater. It is preferable to adjust the supply flow rate of organic wastewater into the aerobic treatment device so that the temperature in the aerobic treatment device is maintained at 15 to 40 ° C. by heat.

Organics supplied into the aerobic treatment equipment so that the temperature inside the aerobic treatment equipment is maintained at 15 to 40 ° C. by the heat of biological reaction generated by the decomposition of organic substances contained in the organic wastewater during the shutdown period. By adjusting the supply flow rate of the sex wastewater and the BOD load, it is possible to perform the treatment more stably by the heat of biological reaction even during the operation stop period without using external equipment.

According to the method for treating organic waste according to the embodiment of the present invention, aerobic treatment is performed so that the temperature in the aerobic treatment apparatus is maintained only by the heat of biological reaction generated by the aerobic biological treatment of organic waste. By adjusting the supply flow rate (volume flow rate) of organic wastewater supplied into the equipment, it is basically unnecessary to heat or cool aerobic biological treatment by external equipment, so it is preferable to supply organic wastewater. The heat generated in the aerobic treatment tank can be effectively used, and the treatment and equipment can be simplified and downsized.

(Organic wastewater treatment equipment)
As shown in FIG. 1, the organic waste treatment apparatus according to the embodiment of the present invention includes an aerobic treatment apparatus (first-stage aerobic treatment apparatus 1) for treating organic wastewater with aerobic organisms and organic wastewater. A flow rate that adjusts the supply flow rate of organic wastewater supplied into the aerobic treatment device so that the temperature inside the aerobic treatment device is maintained at 15 to 40 ° C. by the heat of biological reaction generated by the decomposition of the organic matter contained in the aerobic treatment device. The adjusting means 2 is provided. In the example of FIG. 1, an example in which the second-stage aerobic treatment device 7 is connected to the subsequent stage of the first-stage aerobic treatment device 1, is based on the aerobic biological treatment of the first-stage aerobic treatment device 1. Of course, when the treated water satisfies a predetermined water quality standard, the second-stage aerobic treatment device 7 can be omitted.

As the first-stage aerobic treatment device 1, by using a device in which the volume ratio of gas to liquid (volume of liquid / volume of gas) β in the aerobic treatment device is 0.2 or less, other than organic wastewater Since it is not necessary to consider the influence of the heat balance of the liquid phase of the above, the influence of the biological reaction heat generated by the decomposition of organic matter contained in the organic wastewater can be estimated more appropriately and accurately. As such a first-stage aerobic treatment device 1, for example, an aerobic treatment device using a sprinkling filter method can be used. In the following embodiments, an example using a watering filter will be used as an example, but it is of course not intended to be limited to the following aspects.

The watering filter method is one of the aerobic biological treatment methods, and is a method of obtaining biologically treated water by decomposing organic matter in the organic wastewater sprayed by the action of microorganisms adhering to the surface of the filter medium. is there. It is generally known that the watering filter method makes the surface of the biofilm aerobic and the inside of the biofilm anaerobic. Therefore, when the sprinkling filter is operated with a load that allows nitrification to proceed, the nitrification reaction proceeds on the surface of the biofilm, and the denitrification reaction proceeds inside the biofilm. Excellent in terms of.

There are no particular restrictions on the specific configuration of the carrier used for the watering filter, the watering part, and the like. The material of the carrier may be any material as long as microorganisms adhere to it, and plastics, crushed stones and the like are typically used. The shape of the carrier may be any shape such as a plate shape, a spherical shape, a columnar shape, a rectangular parallelepiped shape, and a hollow shape. The filling rate of the carrier with respect to the capacity of the reaction vessel is preferably 40 to 80%, preferably 50 to 70%. In the case of a membranous carrier, it is preferable to fill the surface so that the area of the surface of the membrane relative to the capacity of the reaction vessel is 0.05 to 0.15 m ² / m ³ .

In order to carry out biological treatment more efficiently and stably, a structure in which the separated liquid after solid-liquid separation supplied to the sprinkling filter and oxygen in the sprinkling filter permeate facing each other across the membrane surface is provided. It is more preferable that the membranous carrier 20 as shown in FIG. 2 having the membrane carrier 20 is arranged in the watering filter bed.

The film-like carrier 20 includes a support 21 and a film 22 supported by the support 21, and the film 22 has a loop shape covering the support 21, and the separation liquid permeates from the outer surface of the loop-shaped film 22. However, oxygen is configured to permeate from the space 23 formed on the inner surface of the loop-shaped film 22 to the outer surface of the film. The film 22 includes a curved portion 22a that curves outside the support 21, and stretched portions 22b and 22c that extend substantially parallel to each other from both ends of the curved portion 22a, and the lower end side of the film 22, that is, the film 22 is arranged. On the side facing the bottom surface of the aerobic treatment apparatus, an opening 22d is formed for discharging sludge (not shown) that accumulates on the inner surface of the membrane 22 and then peels off to the outside of the space 23.

When an aerobic treatment device using the sprinkling filter method is used as the first-stage aerobic treatment device 1, the temperature of the organic waste water treated in the sprinkling filter is 30 to 40 ° C, more preferably 33 ° C to 38. It is preferable that the flow rate adjusting means 2 adjusts the supply flow rate (volume flow rate) of the organic waste water supplied into the sprinkler filter bed so that the temperature is adjusted to ° C. As a result, more efficient aerobic biological treatment can be achieved by suppressing the generation of flies while maintaining the BOD removal rate in the watering filter bed as high as about 65 to 85%.

The flow rate adjusting means 2 is not particularly limited as long as it is a device capable of adjusting the volumetric flow rate of organic wastewater, and a general-purpose device such as a valve can be used. The flow rate adjusting means 2 is connected to the control means 10, and can be configured to change the supply flow rate based on the output signal output from the control means (device) 10.

The control means 10 decomposes, for example, organic substances contained in the organic waste water supplied into the first-stage aerobic treatment device 1 based on the heat balance calculation result of the biological reaction heat generated in the first-stage aerobic treatment device 1. If the temperature inside the aerobic reactor is estimated to be below 15 ° C due to the heat of the biological reaction generated by the above, the flow rate is controlled to increase the concentration of organic matter in the organic wastewater, and it is estimated to exceed 40 ° C. In this case, it is possible to control the flow rate so as to reduce the concentration of organic matter in the organic wastewater.

Further, the organic waste treatment apparatus according to the embodiment of the present invention has a water temperature measuring means 3 for measuring the water temperature of the organic waste before aerobic biological treatment, and the first-stage aerobicity based on the measurement result of the water temperature. Dilution ratio determining means (not shown) for determining the dilution ratio of the diluting fluid that dilutes the organic waste water and organic in order to adjust the BOD concentration and the ammoniacal nitrogen concentration of the organic waste water supplied to the treatment apparatus 1. A diluting fluid supply means 6 for supplying the diluting fluid to the waste water can be provided.

The dilution ratio determining means can be controlled by the control signal output by the control means 10. The dilution ratio determining means is based on, for example, the relationship between the water temperature of the organic wastewater and the dilution ratio of the diluted fluid, which are set in advance in consideration of the biological reaction heat generated by the decomposition of the organic wastewater in the first-stage aerobic treatment apparatus 1. By determining the dilution ratio, the water temperature of the organic waste water in the first-stage aerobic treatment apparatus 1 can be adjusted to a more appropriate range. The first-stage aerobic treatment device 1 can be provided with a water temperature measuring means 5 for measuring the water temperature of the organic waste water in the first-stage aerobic treatment device 1. A water temperature measuring means 4 for measuring the water temperature of the diluting fluid may be provided. The water temperature measurement results by the water temperature measuring means 4 and 5 are output to the control means 10.

The control means 10 can be provided with a heat balance calculation means for calculating the heat balance in the aerobic processing apparatus by using the above equations (1) to (5), and the heat balance calculation result by the heat balance calculation means can be obtained. Based on this, by outputting information on the supply flow rate of the organic wastewater to be adjusted by the flow rate adjusting means 2, the heat generated in the aerobic treatment tank by the supply of the organic wastewater can be effectively utilized and included in the organic wastewater. The temperature of the organic wastewater in the first-stage aerobic treatment apparatus 1 can be maintained at a temperature suitable for treatment by microorganisms by utilizing the heat of the biological reaction due to the decomposition of the organic matter and the water temperature of the organic wastewater.

As the second-stage aerobic treatment device 7, an aerobic treatment device having a lower BOD load than the first-stage aerobic treatment device 1 can be used, and for example, an activated sludge treatment device, a filtration device, and the like can be preferably used. ..

When treating organic wastewater with aerobic organisms, it is important to maintain the temperature inside the aerobic treatment device at the optimum temperature in order to maintain the biological activity of microorganisms that decompose organic matter, and external heating is required when the water temperature is low. It was necessary, and when the water temperature was high, it was necessary to cool it by heat exchange treatment or the like. Therefore, in the conventional method, it is necessary to provide an external facility for temperature control.

According to the organic wastewater treatment apparatus according to the embodiment of the present invention, the amount of heat possessed by the organic wastewater itself, that is, the water temperature of the organic wastewater and the heat of biological reaction due to the decomposition of organic substances contained in the organic wastewater are utilized. Therefore, the supply flow rate of the organic waste water is adjusted by the flow rate adjusting means 2 so that the temperature in the aerobic treatment device is maintained at 15 to 40 ° C. As a result, the inside of the first-stage aerobic treatment apparatus can be maintained at a temperature suitable for aerobic biological treatment without using an external facility for temperature adjustment, and stable wastewater treatment can be performed.

In the example of FIG. 1, the case of adjusting the supply flow rate of the organic waste water in the first-stage aerobic treatment device 1 has been described as an example, but the first-stage aerobic treatment device 7 is also favored in the first stage. It goes without saying that the same processing as that of the temper processing apparatus 1 can be performed.

Examples of the present invention are shown below together with comparative examples, but these examples are provided for a better understanding of the present invention and its advantages, and are not intended to limit the invention.

(Example 1)
<Laboratory experiment to estimate the coefficient of heat of biological oxidation>
Sprinkling filter bed treatment device (experimental device effective capacity 36L) in which the film-like carrier 20 shown in FIG. 2 is housed in the first-stage aerobic treatment device (also referred to as “first-stage aerobic machine tank”) of the organic wastewater treatment device of FIG. Was used, and the high-concentration organic wastewater shown in FIG. 4 was treated by adding the low-concentration organic wastewater shown in FIG. 4 as a diluting fluid as needed.

As shown in FIG. 4, the high-concentration organic wastewater has a water temperature of 27 ° C., SS200 mg / L, COD _Cr 16,000 mg / L, BOD8,000 mg / L, and NH _4- N300 mg / L, and the low-concentration organic wastewater has a water temperature. 20 ° C., SS 20 mg / L, COD _Cr 300 mg / L, BOD 100 mg / L, NH _4- N 6 mg / L.

Figure 5 shows the inflow of high-concentration organic wastewater (also referred to as “high-concentration wastewater”) and low-concentration organic wastewater (also referred to as “low-concentration wastewater”) into the first-stage aerobic tank, the inflow raw water BOD concentration, and The change in the water temperature in the first stage opportunity tank (also called "water temperature in the reactor") is shown. FIG. 6 shows the relationship between the inflow BOD concentration and the water temperature in the reaction tank.

As shown in FIG. 5, the inflow of low-concentration organic wastewater was changed to 6 types of 0, 1, 2, 4, 7, and 10 (L / d), and 6 series were examined. The inflow BOD concentrations of each series were 8000, 7380, 6680, 5740, 4750 and 4050 mg / L. The BOD volume loading of the reaction vessel was in the range of 2 to 4 kg / m ³ / d.

When the inflow of low-concentration organic wastewater is 4 L / d or more and the inflow BOD concentration is 5740 mg / L or less, the water temperature in the reactor is 33 to 39 ° C, and the BOD removal rate is 70 to 80%, which is a stable BOD treatment performance. showed that. On the other hand, when the bypass amount of low-concentration organic wastewater is 4 L / d or less and the inflow water BOD concentration is 5740 mg / L or more, the temperature inside the reactor becomes 40 ° C. or more, the BOD removal rate becomes 40 to 60%, and the BOD treatment performance deteriorates. Indicated.

Based on the above results, the values of Y1 to Y4 were obtained from the equations (1) to (5). Under the treatment conditions of Example 1, the BOD load of the reaction vessel is as high as 2 to ⁴ kg / m ³ / d, so the nitrification reaction (Y2) of the formula (3) does not proceed. Further, since it is not necessary to consider other biological oxidation reactions (Y4) and the calorific value (Y3) by the circulation pump, it is sufficient to consider Y1 and α on the right side of the equation (5). The heat of biological reaction A per unit weight associated with the BOD decomposition of the formula (2) was adopted as 3,800 Kcal / kg-BOD. Since the reactor is made of vinyl chloride and has a low thermal diffusivity, the heat balance was calculated with the thermal diffusivity α set to α = 0.95.

<Demonstration experiment in which the water temperature in the reactor is controlled>
A sprinkler filter bed treatment device (experimental device effective capacity 2 m ³ ) containing the film-like carrier 20 shown in FIG. 2 was used as the first-stage aerobic treatment device of the organic wastewater treatment device shown in FIG. Experiments were conducted using concentrated organic wastewater and low-concentration organic wastewater. The high-concentration organic wastewater temperature was varied in the range of 30-15 ° C. The low-concentration drainage water temperature was set to a constant condition of 20 ° C.

FIG. 7 shows changes in the high-concentration organic wastewater temperature, the inflow water BOD concentration, and the water temperature in the reactor. The upper figure of FIG. 7 shows the change over time in the supply flow rate of the high-concentration organic wastewater and the low-concentration wastewater, the middle figure of FIG. 7 shows the transition of the BOD concentration of the inflow water, and the lower figure of FIG. 7 shows the water temperature of the high-concentration organic wastewater. And the change over time in the water temperature in the reactor.

Eq. (5) was calculated using the values of Y1 to Y4 obtained in the laboratory experiment for estimating the coefficient of the above-mentioned biological reaction heat A when the high-concentration organic wastewater temperature was changed in the range of 30 to 15 ° C. Calculated. Calculate equation (5) under the conditions of high-concentration organic wastewater temperature 30 ° C, flow rate 0.75 m ³ / d, and low-concentration organic wastewater temperature 20 ° C, and set the low-concentration organic wastewater flow rate to 0.8 m ³ / d. The inflow BOD concentration was set to 4000 mg / L. As a result, the water temperature in the reactor could be maintained at 33 to 36 ° C.

Next, formula (5) was calculated under the conditions of high-concentration organic wastewater temperature 25 ° C, flow rate 0.75 m ³ / d, and low-concentration organic wastewater temperature 20 ° C, and the low-concentration organic wastewater flow rate was 0.75 m ³ /. It was set to d, and the inflow BOD concentration was 4000 mg / L. As a result, the water temperature in the reactor could be maintained at 32 to 33 ° C.

Next, formula (5) was calculated under the conditions of a high-concentration organic wastewater flow rate of 0.75 m ³ / d and a low-concentration organic wastewater temperature of 20 ° C., and the low-concentration organic wastewater flow rate was 0.5 m ³ / d. It was set to d and the inflow BOD concentration was 5000 mg / L. As a result, the water temperature in the reactor could be maintained at 32 to 34 ° C.

Next, formula (5) was calculated under the conditions of a high-concentration organic wastewater flow rate of 0.75 m ³ / d at 15 ° C. and a low-concentration organic wastewater temperature of 20 ° C., and the low-concentration organic wastewater flow rate was set to 0 m ³ / d. The inflow BOD concentration was set to 8000 mg / L. As a result, the water temperature in the reactor could be maintained at 33 to 35 ° C.

Even when the high-concentration organic wastewater temperature fluctuates stepwise in the range of 30 ° C to 15 ° C, the water temperature in the reactor can be adjusted to 32 to 35 ° C by appropriately controlling the amount of low-concentration organic wastewater. It was possible to maintain the range and enable stable BOD processing.

(Example 2)
<Adjusting the water temperature in the reactor and suppressing the generation of butterfly flies>
A sprinkler filter bed treatment device (experimental device effective capacity 4 m ³ ) containing the film-like carrier 20 shown in FIG. 2 was used as the first-stage aerobic treatment device of the organic wastewater treatment device shown in FIG. Experiments were conducted using concentrated organic wastewater and low-concentration organic wastewater.

FIG. 8 shows high-concentration organic wastewater properties and low-concentration organic wastewater properties. High-concentration organic wastewater has a water temperature of 24 ° C, SS500 mg / L, COD _Cr 7,000 mg / L, BOD 3,000 mg / L, NH _4- N 1,500 mg / L, and low-concentration organic wastewater has a water temperature of 24 ° C, SS100 mg. / L, COD _Cr 600 mg / L, BOD 150 mg / L, NH _4- N 54 mg / L. In the series of Comparative Examples, high-concentration organic wastewater and low-concentration organic wastewater were mixed and then passed through, and in the series of Example 2, only high-concentration organic wastewater was passed.

FIG. 9 shows the amount of high-concentration organic wastewater, the amount of low-concentration organic wastewater, the inflow water BOD concentration, the water temperature in the reactor, and the generation status of butterfly flies. The occurrence of Psychodidae was visually evaluated. In the comparative example, the inflow water BOD concentration was 1,580 mg / L, the water temperature in the reactor was 26 to 28 ° C., and the occurrence of flies was ++ (more) to +++ (very more). On the other hand, in Example 2, the inflow water BOD concentration was 3,000 mg / L, the water temperature in the reactor was 32 to 34 ° C., and the occurrence of flies was + (less) to − (no occurrence was observed). In this way, it was possible to suppress the occurrence of Psychodidae by maintaining the water temperature in the reactor at 30 to 40 ° C.

1 ... First-stage aerobic treatment device 2 ... Flow rate adjusting means 3, 4, 5 ... Water temperature measuring means 6 ... Diluted fluid supply means 7 ... Second-stage aerobic treatment device 10 ... Control means 20 ... Membrane-like carrier 21 ... Support 22d ... Opening 22b ... Stretched portion 22 ... Membrane 22a ... Curved portion 23 ... Space

Claims (9)

In an aerobic treatment device that aerobicly treats one or more organic wastewaters
Aerobicity taking into account the water temperature of the organic wastewater, the calorific value associated with the BOD decomposition of the organic wastewater, the calorific value associated with the nitrification of the organic wastewater, and the calorific value associated with the operation of the mechanical equipment of the aerobic treatment apparatus. The heat balance calculation in the processing device is performed, and based on the calculation result of the heat balance calculation, the temperature in the aerobic processing device is supplied to the aerobic processing device so as to be maintained at 15 to 40 ° C. A method for treating organic wastewater, which comprises adjusting the supply flow rate of the organic wastewater. The method for treating organic wastewater according to claim 1, which comprises adjusting the BOD concentration and the ammoniacal nitrogen concentration in the aerobic treatment apparatus by adjusting the supply flow rate of the organic wastewater. Claim 1 or 2 including performing the heat balance calculation based on the following relational expressions (1) to (5) and determining the supply flow rate of the organic wastewater to be supplied into the aerobic treatment apparatus. The method for treating organic wastewater described in.
X1 (Kcal / d) = Supply flow rate (m ³ / d) x (Treatment water temperature (° C) -Supply water temperature (° C)) x 0.001 ... (1)
Y1 (Kcal / d) = Bioreaction heat A (Kcal / kg-BOD) per unit weight associated with BOD decomposition x amount of removed BOD (kg-BOD / d) ... (2)
Y2 (Kcal / d) = heat of biological reaction per unit weight associated with nitrification B (Kcal / kg-N) x NH _4- N vitrification amount (kg-N / d) ... (3)
Y3 (Kcal / d): Calorific value associated with the operation of mechanical equipment of the aerobic processing device ... (4)
X1 = (Y1 + Y2 + Y3) × α ・ ・ ・ (5)
(Α indicates the thermal diffusivity (-) from the aerobic treatment device) Claims 1 to 3 include adjusting the supply flow rate of the organic waste water so that the aerobic treatment apparatus is a sprinkling filter and the temperature in the sprinkling filter is maintained at 30 to 40 ° C. The method for treating organic wastewater according to any one item. The organic wastewater according to any one of claims 1 to 4, wherein the gas-to-liquid volume ratio (liquid volume / gas volume) β in the aerobic treatment apparatus is 0.2 or less. Processing method. The method for treating organic wastewater according to any one of claims 1 to 5, wherein the BOD concentration of the organic wastewater supplied into the aerobic treatment apparatus is 1000 to 10000 mg / L. An aerobic treatment device that treats one or more organic wastewater with aerobic organisms.
It is preferable to take into consideration the water temperature of the organic wastewater, the calorific value associated with the BOD decomposition of the organic wastewater, the calorific value associated with the nitrification of the organic wastewater, and the calorific value associated with the operation of the mechanical equipment of the aerobic treatment apparatus. The heat balance in the aerobic treatment device is calculated, and based on the calculation result of the heat balance calculation, the temperature in the aerobic treatment device is supplied to the aerobic treatment device so as to be maintained at 15 to 40 ° C. A device for treating organic wastewater, which comprises a flow rate adjusting means for adjusting the supply flow rate of the organic wastewater. A water temperature measuring means for measuring the water temperature of the organic wastewater,
A dilution ratio determining means for determining the dilution ratio of the dilution fluid for diluting the organic wastewater based on the measurement result of the water temperature, and
The organic wastewater treatment apparatus according to claim 7, further comprising a diluted fluid supply means for supplying the diluted fluid to the organic wastewater. The aerobic treatment device is a watering filter,
A claim comprising the flow rate adjusting means adjusting the supply amount of the organic waste water so that the temperature of the organic waste water in the sprinkling filter is adjusted to 30 to 40 ° C. The organic wastewater treatment apparatus according to 7 or 8.