JP7177014B2 - Organic wastewater treatment method and organic wastewater treatment apparatus - Google Patents

Description

TECHNICAL FIELD The present invention relates to an organic wastewater treatment method and an organic wastewater treatment apparatus.

The activated sludge process is widely used as an aerobic biological treatment for sewage, night soil, and organic wastewater discharged from food factories. Temperature condition is an important parameter in operating activated sludge treatment.

When the temperature of the inflowing waste water is low, or when activated sludge treatment is performed in cold regions, it is necessary to adjust the heating of steam or the like. Particularly in cold regions, if the operation is stopped when the outside air temperature is low, the operation may be restarted after a long holiday such as the New Year's holiday after adjusting the temperature.

On the other hand, if the temperature of the inflow wastewater is high, or if the high BOD concentration wastewater with a BOD concentration of 5000 to 10000mg/L or more is treated with activated sludge, depending on the temperature of the wastewater, aeration is caused by the heat of biological reaction accompanying BOD decomposition. The temperature of the bath may become too high. In the nitrification and denitrification processes in human waste treatment, the water temperature in the nitrification and denitrification tanks may become too high due to the heat of biological reaction and the Joule heat of the aerator. Therefore, as temperature control measures, a cooling method using an external heat exchanger, a cooling method using an in-tank heat exchanger, a cooling method using a refrigerator, or a cooling method using underground water is required.

Composting is an example of a treatment method that utilizes the heat of biological reaction. It is known that when organic waste is composted, the temperature in the fermentation tank rises to 70-80°C due to the heat of biological reaction in the primary fermentation stage.

For example, the invention described in Patent Document 1 is known as a method for treating organic waste water using the heat of biological reaction. In the invention described in Patent Document 1, biologically treated water whose temperature has increased due to the heat of biological reaction during night soil treatment is used as a heat source for a heat pump, which is an external facility, for temperature adjustment, thereby achieving both water purification and energy saving. It is stated that it is possible to achieve

JP-A-58-95589

However, the invention described in Patent Literature 1 supplies the biologically treated water whose temperature has been raised by the heat of biological reaction to external equipment such as a heat pump, thereby increasing the equipment area and complicating the equipment. In addition, the invention described in Patent Document 1 also requires periodic maintenance work for the external equipment. Therefore, it would be useful if a method and apparatus for heating or cooling an aerobic treatment apparatus more efficiently by a method different from the invention described in Patent Document 1 could be obtained.

In view of the above problems, the present invention is capable of effectively utilizing the heat generated in the aerobic treatment tank by the supply of organic wastewater, and maintains the inside of the aerobic treatment apparatus at a temperature suitable for aerobic treatment, thereby stably treating wastewater. To provide an organic wastewater treatment method and treatment apparatus capable of performing

In order to solve the above problems, the present inventors have made intensive studies and found that the water temperature of the organic wastewater supplied to the aerobic treatment device and the heat of biological reaction accompanying the decomposition of organic matter contained in the organic wastewater are favorable. It is effective to adjust the supply flow rate of the organic wastewater supplied to the aerobic treatment equipment based on the heat balance in the aerobic treatment equipment that takes into account the amount of heat generated by the operation of the mechanical equipment of the aerobic treatment equipment. I got the knowledge that there is.

In one aspect of the embodiment of the present invention completed based on the above findings, in an aerobic treatment apparatus for aerobically biologically treating one or more organic wastewaters, the temperature of the organic wastewater, the amount of the organic wastewater A heat balance calculation is performed in the aerobic treatment equipment, taking into consideration the calorific value associated with BOD decomposition, the calorific value associated with the nitrification of organic wastewater, and the calorific value associated with the operation of the mechanical equipment of the aerobic treatment equipment, and the heat balance calculation is performed. Organic wastewater including adjusting the supply flow rate of the organic wastewater supplied to the aerobic treatment device so that the temperature in the aerobic treatment device is maintained at 15 to 40 ° C. based on the calculation results of is a processing method.

In one embodiment of the organic wastewater treatment method according to the embodiment of the present invention, the BOD concentration and the ammonia nitrogen concentration in the aerobic treatment apparatus are adjusted by adjusting the supply flow rate of the organic wastewater. include.

In another embodiment of the organic wastewater treatment method according to the embodiment of the present invention, heat balance calculation is performed based on the following relational expressions (1) to (5), and 3. The method for treating organic waste water according to claim 1, further comprising determining the supply flow rate of the organic waste water to be supplied.
X1 (Kcal/d) = supply flow rate (m ³ /d) × (treated water temperature (°C) - supply water temperature (°C)) × 0.001 (1)
Y1 (Kcal/d) = heat of biological reaction A per unit weight associated with BOD decomposition (Kcal/kg-BOD) x amount of BOD removed (kg-BOD/d) (2)
Y2 (Kcal/d) = Heat of biological reaction B per unit weight associated with nitrification (Kcal/kg-N) x NH ₄ -N nitrification amount (kg-N/d) (3)
Y3 (Kcal/d): calorific value associated with mechanical equipment operation of aerobic treatment equipment (4)
X1=(Y1+Y2+Y3)×α (5)
(α indicates the heat dissipation rate (-) from the aerobic treatment equipment)

In still another embodiment of the organic wastewater treatment method according to the embodiment of the present invention, the aerobic treatment device is a trickling filter, and the temperature in the trickling filter is maintained at 30 to 40 ° C. , including adjusting the feed flow of organic wastewater.

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

In still another embodiment of the organic wastewater treatment method according to the embodiment of the present invention, the organic wastewater supplied to the aerobic treatment apparatus has a BOD concentration of 1000 to 10000 mg/L.

According to another aspect of the present invention, there is provided an aerobic treatment apparatus for aerobic biological treatment of one or more organic wastewaters, wherein the water temperature of the organic wastewater and heat generation associated with BOD decomposition of the organic wastewater are A heat balance calculation is performed in the aerobic treatment equipment, taking into consideration the amount of heat generated by nitrification of organic wastewater, and the amount of heat generated due to the operation of the mechanical equipment of the aerobic treatment equipment. Based on this, treatment of organic wastewater provided with a flow rate adjusting means for adjusting the supply flow rate of the organic wastewater supplied into the aerobic treatment apparatus so that the temperature in the aerobic treatment apparatus is maintained at 15 to 40 ° C. It is a device.

In one embodiment of the organic wastewater treatment apparatus according to the embodiment of the present invention, water temperature measuring means for measuring the water temperature of the organic wastewater and a diluent fluid for diluting the organic wastewater based on the water temperature measurement result and a dilution fluid supply means for supplying a 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 trickling filter, and the flow rate adjusting means is such that the temperature of the organic wastewater in the trickling filter is 30%. A flow regulating means includes regulating the supply of organic waste water so that the temperature is adjusted to ∼40°C.

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

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows an example of the processing apparatus of the organic waste water which concerns on embodiment of this invention. FIG. 2 is a cross-sectional view showing a configuration example of a film-like carrier of a trickling filter bed provided in the organic wastewater treatment apparatus according to the embodiment of the present invention. FIG. 2 is a side view showing a configuration example of a film-like carrier of a trickling filter bed provided in the organic wastewater treatment apparatus according to the embodiment of the present 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 amount of high-concentration organic wastewater and low-concentration organic wastewater flowing into the first-stage aerobic treatment apparatus, the BOD concentration of the inflow raw water, and the water temperature in the first-stage favorable tank. 4 is a graph showing the relationship between the BOD concentration of inflowing raw water, the water temperature in the reactor, and the BOD treatment performance. When the flow rate of high-concentration organic wastewater is constant and the water temperature of high-concentration organic wastewater is changed in the range of 30 to 15°C, the inflow of low-concentration organic wastewater is adjusted to optimize the BOD concentration of the inflow raw water. 10 is a graph showing changes in water temperature in the reactor when 4 is a table showing properties of high-concentration organic waste water and low-concentration organic waste water used in Example 2. FIG. It is a table showing the relationship between the amount of high-concentration organic wastewater, the amount of low-concentration organic wastewater, the concentration of influent BOD, the water temperature in the reactor, and the occurrence of moth flies.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments shown below are examples of devices and methods for embodying the technical idea of the present invention. not something to do.

(Method for treating organic wastewater)
An organic wastewater treatment method according to an embodiment of the present invention is an aerobic treatment apparatus for aerobically biologically treating one or more organic wastewaters, wherein the water temperature of the organic wastewater and the BOD decomposition of the organic wastewater are Calculation of the heat balance in the aerobic treatment equipment taking into account at least one of the calorific value associated with nitrification and the calorific value associated with nitrification, and the calorific value associated with the operation of the mechanical equipment of the aerobic treatment equipment. Based on the result, adjusting the supply flow rate of the organic wastewater supplied into the aerobic treatment apparatus so that the temperature in the aerobic treatment apparatus is maintained at 15 to 40°C.

Organic waste water can be sewage, night soil, and organic waste water discharged from food factories. In particular, organic wastewater having a biochemical oxygen demand (BOD concentration) of 1000 mg/L or more, more preferably 5000 mg/L, and still more preferably 10000 mg/L or more and having a high organic matter concentration is used as the organic wastewater according to the present embodiment. It can be used conveniently.

As an aerobic treatment apparatus, an activated sludge apparatus, a trickling filter, a fluid carrier method, a contact oxidation method, a biofilm filtration method, a rotating disk method, and the like can be used. In particular, it is preferable to use an aerobic treatment apparatus in which the volume ratio of gas to liquid (volume of liquid/volume of gas) β in the aerobic treatment apparatus 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, there is no need to consider the influence of the heat balance of the liquid phase other than the organic wastewater. Biological reaction calorie 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 trickling filter and a rotating disc (gas phase portion).

If the BOD concentration and the ammonia nitrogen (NH ₄ —N) concentration of the organic wastewater supplied to the aerobic treatment equipment are too high, the organic wastewater in the aerobic treatment equipment will be degraded by the heat of biological reaction generated in the aerobic treatment equipment. In some cases, the water temperature of the wastewater becomes too high, inhibiting biological activity and requiring external equipment such as a cooling device. On the other hand, if the BOD concentration and the ammonia nitrogen concentration of the organic waste water are too low, it becomes difficult to heat the organic waste water by the heat of biological reaction generated in the aerobic treatment apparatus, and external equipment such as a heating device may be required.

The BOD concentration of the organic wastewater supplied to the aerobic treatment apparatus is preferably 1000-10000 mg/L, more preferably 2000-5000 mg/L, and still more preferably 3000-4000 mg/L.

In the aerobic treatment apparatus, bioreaction heat is generated by a decomposition reaction of organic substances contained in organic wastewater due to aerobic biotreatment. In this embodiment, by adjusting the supply flow rate of the organic matter contained in the organic wastewater supplied into the aerobic treatment apparatus to a suitable range, the temperature inside the aerobic treatment apparatus can be adjusted to the level at which organic matter is decomposed using microorganisms. The temperature is controlled at 15 to 40°C suitable for the reaction. As a result, the heat generated in the aerobic treatment tank by the supply of organic wastewater can be effectively used to maintain the inside of the aerobic treatment apparatus at a temperature suitable for aerobic biological treatment by microorganisms, so the equipment can be simplified. In addition, it is possible to perform stable wastewater treatment.

In order to appropriately 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 water temperature measurement results, a dilution fluid is used to dilute the organic wastewater. By diluting, it is preferable to adjust the supply flow rate of the organic wastewater to be supplied into the aerobic treatment apparatus, specifically, the BOD concentration and the ammonia nitrogen concentration to be within a suitable range.

For example, if the water temperature of the organic wastewater before aerobic biological treatment is too low due to the influence of the outside air temperature, etc., the biological activity of microorganisms in the aerobic treatment equipment can be improved by utilizing the heat of biological reaction in the aerobic treatment equipment. In order to maintain the temperature condition, the concentration of organic matter in the organic wastewater, specifically, the concentration of BOD and ammonia nitrogen is increased to increase the heat of biological reaction in the aerobic treatment device. make adjustments to increase the supply flow rate of organic wastewater.

Conversely, if the water temperature of the organic wastewater before aerobic biological treatment is too high, the amount of organic wastewater supplied is reduced or the dilution ratio of the diluent fluid is increased to reduce the organic matter in the organic wastewater. Specifically, the BOD concentration and the ammonia nitrogen concentration are lowered, and the supply flow rate of the organic waste water is adjusted so that the amount of heat generated by the biological reaction in the aerobic treatment apparatus can be kept small.

As the diluent fluid, a diluent fluid different in water temperature, BOD concentration and/or ammonia nitrogen concentration from organic waste water (raw water) can be used. For example, water, river water, or the like may be used as the diluent fluid, or low-organic waste water, etc., having a BOD concentration lower than that of raw water may be used. Organic wastewater with a BOD concentration of less than 1000 mg/L, more typically with a BOD concentration of 500 mg/L or less can be used as the low organic wastewater.

In order to adjust the supply flow rate of the organic wastewater supplied into the aerobic treatment apparatus to a suitable range, it is necessary to estimate the heat balance in consideration of the heat of biological reaction in the aerobic treatment apparatus. Specifically, the water temperature of organic wastewater (raw water) before aerobic biological treatment, the calorific value associated with BOD decomposition of organic wastewater and the calorific value associated with nitrification treatment, and the heat associated with the operation of mechanical equipment for aerobic treatment equipment. It is preferable to perform a heat balance calculation in the aerobic treatment apparatus that takes into account at least the amount, and adjust the supply flow rate of the organic wastewater supplied to the aerobic treatment apparatus 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 BOD decomposition of organic waste water and the heat of biological reaction per unit weight associated with nitrification of ammoniacal nitrogen take constant values. In this embodiment, the heat balance in the aerobic treatment apparatus is calculated using these values of the heat of biological reaction per unit weight. For example, the heat of biological reaction per unit weight associated with BOD decomposition can be 3,000 to 5000 Kcal/kg-removed BOD, and the heat of biological reaction associated with nitrification of ammonia nitrogen is 5000 to 7000 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 BOD decomposition, the amount of heat generated by BOD decomposition of organic wastewater can be estimated. Similarly, the amount of heat generated by the nitrification process can be estimated from the relationship between the amount of ammonia nitrogen nitrified in the aerobic treatment apparatus and the amount of biological reaction heat per unit weight involved in the nitrification process of the ammonia 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 biological treatment and the relationship between the supply flow rate of the organic wastewater flowing into the aerobic biological treatment. Based on these estimation results, by adjusting the supply flow rate of the organic wastewater flowing into the aerobic treatment equipment, the heat of biological reaction generated in the aerobic treatment equipment can be effectively used for heating or cooling. Installation of external equipment can be omitted.

More specifically, heat balance calculation is performed based on the following relational expressions (1) to (5) to 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) × (treated water temperature (°C) - supply water temperature (°C)) × 0.001 (1)
Y1 (Kcal/d) = heat of biological reaction A per unit weight associated with BOD decomposition (Kcal/kg-BOD) x amount of BOD removed (kg-BOD/d) (2)
Y2 (Kcal/d) = Heat of biological reaction B per unit weight associated with nitrification (Kcal/kg-N) x NH ₄ -N nitrification amount (kg-N/d) (3)
Y3 (Kcal/d): calorific value associated with mechanical equipment operation of aerobic treatment equipment (4)
X1=(Y1+Y2+Y3)×α (5)
(α indicates the heat dissipation rate (-) from the aerobic treatment equipment)

α indicates the heat dissipation rate (-) 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 reactor is made of steel plate (iron, stainless steel, etc.), the value of α is preferably set in the range of 0.5 to 0.8 because the material has high thermal conductivity. On the other hand, if the reaction tank is made of concrete or plastic material (vinyl chloride resin, acrylic resin, etc.), the material has low thermal conductivity. 9. It is preferable to set in the range of 0.8 to 1.0 for plastic materials. "Treatment water temperature" indicates the water temperature after treatment in the aerobic treatment apparatus, and "supply water temperature" indicates the water temperature of the supply water supplied to the aerobic treatment apparatus.

The above equations (1) to (5) are examples of conditions that should be taken into consideration at least in the heat balance calculation in the aerobic treatment apparatus, and in the actual heat balance calculation, the above (1) ~ Selecting and omitting Y1 to Y3 and α to be incorporated in the calculation of the formula (5) according to the processing conditions in the aerobic treatment device after considering all the conditions defined by the formula (5) , and other calorific values other than Y1 to Y3 and α can be included in the calculation.

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

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

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

Furthermore, regarding the formula (2), it is preferable to use the following two formulas properly for the removal amount of BOD.
Amount of BOD removed (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 BOD removed (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 BOD containing SS, and “S-BOD” indicates soluble BOD (BOD of liquid filtered through 1.0 μ filter paper))

In formula (2), formula (6) is usually used. On the other hand, in a biofilm method such as a trickling filter, if there is a large amount of biofilm peeling due to operating conditions (BOD load, etc.), the SS concentration in the treated water increases, and the T-BOD concentration in the treated water also increases. In this case, equation (7) may be used to calculate the amount of BOD removed.

In the case of activated sludge treatment, the "calorific value associated with the operation of the mechanical equipment of the aerobic treatment tank" in the formula (4) corresponds to the Joule heat of the aeration equipment. For example, if the power of the aerator is 0.8 kw/m ³ /d, Y3 = 0.8 (kw/m ³ /d) x 24 (h/d) x 860 (kcal/kWh) = 16,512 ( Kcal/m ³ ). On the other hand, in the case of a trickling filter that does not use an aerator, a circulation pump is used.

It is preferable to adjust the flow rate of the organic wastewater 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 trickling filter is used as the aerobic treatment device, the temperature of the trickling filter is maintained at 30 to 40°C, more preferably at 33 to 38°C, thereby suppressing the generation of flies. , it is possible to perform stable wastewater treatment with less pests.

The fruit flies that normally occur in trickling filters grow best at a temperature of 20 to 28°C, but grow poorly at temperatures above 30°C. Therefore, when performing BOD rough treatment of sewage discharge, etc., or when performing aerobic treatment in multiple stages, when the trickling filter method is applied to the first stage aerobic treatment, the temperature of the trickling filter is 30 to 40 ° C., more preferably. By maintaining the temperature at 33°C to 38°C, the generation of flies can be suppressed. Chemicals are usually used for extermination of fruit flies, but by controlling the temperature conditions as in the present application, it is possible to perform stable wastewater treatment with less generation of pests.

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

In such a case, before stopping the operation of the aerobic treatment equipment for a certain period of time, the BOD load of the aerobic treatment equipment is made higher than the BOD load during normal operation for a predetermined period of time, and the aerobic organisms in the organic wastewater are Adjust 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 by the heat of biological reaction generated by the treatment even during the shutdown period. is preferred. In addition, when organic wastewater does not come out for a certain period of time (5 days to 1 week), the temperature of the reaction tank is changed to 33°C to 38°C using known high-concentration organic wastewater (BOD concentration of 10,000 to 50,000mg/L). By adjusting the temperature to ℃, it is possible to suppress the generation of flies.

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

During the operation stop period, organic matter supplied to the aerobic treatment apparatus is maintained at 15 to 40°C by the heat of biological reaction generated by the decomposition of organic matter contained in the organic wastewater. By adjusting the supply flow rate and BOD load of biochemical wastewater, treatment can be performed more stably by the heat of biological reaction even during the shutdown period without using external equipment.

According to the method for treating organic wastewater 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 in the aerobic biological treatment of organic wastewater. By adjusting the supply flow rate (volumetric flow rate) of the organic wastewater supplied into the equipment, it is basically unnecessary to heat or cool the aerobic biological treatment by external equipment, so it is better to supply organic wastewater. The heat generated in the gas treatment tank can be effectively used, and the treatment and equipment can be simplified and downsized.

(Organic wastewater treatment equipment)
The organic wastewater treatment apparatus according to the embodiment of the present invention comprises, as shown in FIG. The flow rate for adjusting the supply flow rate of the organic wastewater supplied to the aerobic treatment apparatus so that the temperature in the aerobic treatment apparatus is maintained at 15 to 40°C by the heat of biological reaction generated by the decomposition of the organic matter contained in the and adjusting means 2 . In the example of FIG. 1, the second-stage aerobic treatment device 7 is connected to the rear stage of the first-stage aerobic treatment device 1, but the aerobic biological treatment of the first-stage aerobic treatment device 1 It goes without saying that the second-stage aerobic treatment device 7 can be omitted if the treated water satisfies a predetermined water quality standard.

As the first-stage aerobic treatment device 1, by using a device in which the volume ratio of gas and liquid (volume of liquid/volume of gas) β in the aerobic treatment device is 0.2 or less, Since it is no longer necessary to consider the effect of the heat balance of the liquid phase, the effect of biological reaction heat generated by the decomposition of organic matter contained in organic wastewater can be estimated more appropriately and accurately. As such a first-stage aerobic treatment apparatus 1, for example, an aerobic treatment apparatus using a trickling filter method can be used. In the following embodiments, an example using a trickling filter will be described as an example, but it is needless to say that the present invention is not intended to be limited to the following aspects.

The trickling filter bed 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 that is sprayed by the action of microorganisms adhering to the surface of the filter medium. be. In the trickling filter bed method, it is generally known that the surface of the biofilm becomes aerobic and the inside of the biofilm becomes anaerobic. Therefore, when the trickling filter is operated under 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 configurations of the carrier, sprinkler section, etc. used in the trickling filter. Any material to which microorganisms can adhere can be used as the material of the carrier, and typical examples thereof include plastics and crushed stone. The shape of the carrier may be plate-like, spherical, columnar, rectangular parallelepiped, hollow, or any other shape. The filling rate of the carrier with respect to the volume of the reaction tank is preferably 40-80%, preferably 50-70%. In the case of a film-like carrier, it is preferable to fill the reaction vessel so that the surface area of the film is 0.05 to 0.15 m ² /m ³ with respect to the capacity of the reaction tank.

In order to perform biological treatment more efficiently and stably, a structure in which the separated liquid after solid-liquid separation supplied to the trickling filter and the oxygen in the trickling filter face each other across the membrane face and permeate is required. It is more preferable that a membrane carrier 20 as shown in FIG. 2 is arranged in the trickling filter bed.

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

When an aerobic treatment apparatus using a trickling filter method is used as the first-stage aerobic treatment apparatus 1, the temperature of the organic wastewater treated in the trickling filter is 30 to 40°C, more preferably 33 to 38°C. It is preferable that the flow rate adjusting means 2 adjust the supply flow rate (volumetric flow rate) of the organic wastewater supplied into the trickling filter bed so that the temperature is adjusted to °C. As a result, it is possible to suppress the generation of flies while maintaining a high BOD removal rate of about 65 to 85% in the trickling filter, thereby achieving more efficient aerobic biological treatment.

The flow rate adjusting means 2 is not particularly limited as long as it is a device that can adjust the volumetric flow rate of the organic wastewater, and for example, 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 such that the supply flow rate is changed based on the output signal output from the control means (device) 10 .

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

Furthermore, the organic wastewater treatment apparatus according to the embodiment of the present invention includes a water temperature measuring means 3 for measuring the water temperature of the organic wastewater before aerobic biological treatment, and a first stage aerobic In order to adjust the BOD concentration and the ammonia nitrogen concentration of the organic wastewater supplied to the treatment apparatus 1, dilution ratio determination means (not shown) for determining the dilution ratio of a dilution fluid that dilutes the organic wastewater; A dilution fluid supply means 6 may be provided for supplying a dilution fluid to the waste water.

The dilution factor determination means can be controlled by control signals output by the control means 10 . The dilution ratio determination means is based on the relationship between the water temperature of the organic wastewater and the dilution ratio of the diluent fluid, which is preset in consideration of the biological reaction heat generated by the decomposition of the organic wastewater in the first-stage aerobic treatment device 1, for example. By determining the dilution ratio with the above, the water temperature of the organic wastewater 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 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 diluent fluid may be provided. Water temperature measurement results obtained by the water temperature measuring means 4 and 5 are output to the control means 10 .

The control means 10 can be provided with heat balance calculation means for calculating the heat balance in the aerobic treatment apparatus using the above equations (1) to (5). 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 used, and the heat contained in the organic wastewater can be effectively used. The temperature of the organic wastewater in the first-stage aerobic treatment apparatus 1 can be maintained at a suitable temperature for treatment with microorganisms by utilizing the heat of biological reaction due to the decomposition of organic matter and the water temperature of the organic wastewater.

As the second-stage aerobic treatment device 7, an aerobic treatment device with a lower BOD load than the first-stage aerobic treatment device 1 can be used. For example, an activated sludge treatment device, a filtration device, etc. can be preferably used. .

When organic wastewater is subjected to aerobic biological treatment, it is important to maintain the optimum temperature inside the aerobic treatment equipment in order to maintain the biological activity of the microorganisms that decompose organic matter. When the water temperature is high, it is necessary to cool the water by heat exchange treatment or the like. Therefore, in the conventional method, it was 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 heat of the organic wastewater itself, that is, the temperature of the organic wastewater and the heat of biological reaction due to the decomposition of the organic matter contained in the organic wastewater are utilized. The flow rate adjusting means 2 adjusts the supply flow rate of the organic wastewater so that the temperature in the aerobic treatment apparatus 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 external equipment 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 wastewater in the first-stage aerobic treatment device 1 was described as an example. Of course, it is possible to perform processing similar to that of the thermal processing device 1 .

Examples of the present invention are presented below along with comparative examples, which are provided for a better understanding of the invention and its advantages and are not intended to be limiting of the invention.

(Example 1)
<Laboratory experiment for estimating the coefficient of heat of biological oxidation>
A trickling filter bed treatment apparatus (experimental apparatus effective capacity: 36 L) in which the membrane-like carrier 20 shown in FIG. was used, and the low-concentration organic waste water shown in FIG. 4 was added as a dilution fluid to the high-concentration organic waste water shown in FIG.

As shown in Fig. 4, the high-concentration organic wastewater has a water temperature of 27°C, SS200mg/L, COD _Cr 16,000mg/L, BOD8,000mg/L, and NH4 _- N300mg/L. 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 amount of high-concentration organic wastewater (also referred to as “high-concentration wastewater”) and low-concentration organic wastewater (also referred to as “low-concentration wastewater”) flowing into the first stage aerobic tank, and the inflow raw water BOD concentration and It shows the change in the water temperature in the first stage opportunity tank (also referred to as "water temperature in the reactor"). FIG. 6 shows the relationship between the inflow BOD concentration and the water temperature in the reactor.

As shown in FIG. 5, the inflow amount of low-concentration organic wastewater was changed to 0, 1, 2, 4, 7, and 10 (L/d), and 6 lines were examined. The influent BOD concentrations for each series were 8000, 7380, 6680, 5740, 4750 and 4050 mg/L. The BOD volume load of the reactor was in the range of 2-4 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%, providing 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 influent BOD concentration is 5740 mg/L or more, the temperature inside the reactor becomes 40°C or more, and the BOD removal rate becomes 40 to 60%, which reduces the BOD treatment performance. Indicated.

Based on the above results, the values of Y1 to Y4 were obtained from formulas (1) to (5). Under the treatment conditions of Example 1, the BOD load in the reaction tank is as high as 2 to 4 kg/m ³ /d, so the nitrification reaction (Y2) of formula (3) does not proceed. In addition, since it is not necessary to consider the other biological oxidation reaction (Y4) and the amount of heat generated by the circulating pump (Y3), it is sufficient to consider Y1 and α in the right side of equation (5). The heat of biological reaction A per unit weight associated with BOD decomposition in formula (2) was adopted as 3,800 Kcal/kg-BOD. Since the material of the reactor is vinyl chloride and has a low heat dissipation rate, the heat dissipation rate was calculated as α=0.95.

<Demonstration experiment controlling the water temperature in the reactor>
A trickling filter bed treatment device (experimental device effective capacity: 2 m ³ ) accommodating the membrane carrier 20 shown in FIG. Experiments were conducted using high-concentration organic wastewater and low-concentration organic wastewater. The high organic wastewater temperature was varied in the range of 30-15°C. The temperature of low-concentration waste water was kept constant at 20°C.

FIG. 7 shows changes in the temperature of the high-concentration organic wastewater, the BOD concentration of the influent, and the water temperature in the reactor. The upper graph in FIG. 7 shows the change over time in the supply flow rate of high-concentration organic wastewater and low-concentration wastewater, the middle graph in FIG. and the time course of water temperature in the reactor.

When varying the temperature of high-concentration organic wastewater in the range of 30 to 15 ° C., formula (5) is calculated using the values of Y1 to Y4 obtained in laboratory experiments for estimating the coefficient of the heat of biological reaction A described above. Calculated. Formula (5) was calculated under the conditions of a high-concentration organic wastewater temperature of 30°C, a flow rate of 0.75m ³ /d, and a low-concentration organic wastewater temperature of 20°C, and the low-concentration organic wastewater flow rate was set to 0.8m ³ /d was set to an influent BOD concentration of 4000 mg/L. As a result, the water temperature in the reactor could be maintained at 33-36°C.

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

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

Next, formula (5) is calculated under the conditions of high-concentration organic wastewater flow rate of 15°C and low-concentration organic wastewater temperature of 20°C, and the low ^- concentration organic wastewater flow rate is set to 0 ^m3 /d. was set to an influent BOD concentration of 8000 mg/L. As a result, the water temperature in the reactor could be maintained at 33-35°C.

Even when the temperature of the high-concentration organic wastewater fluctuates step by step in the range of 30°C to 15°C, the water temperature in the reactor can be maintained at 32-35°C by appropriately controlling the amount of the low-concentration organic wastewater. It can be maintained within the range, enabling stable BOD treatment.

(Example 2)
<Adjusting water temperature in the reactor and suppressing the generation of fruit flies>
A trickling filter bed treatment device (experimental device effective capacity: 4 m ³ ) accommodating the membrane carrier 20 shown in FIG. Experiments were conducted using high-concentration organic wastewater and low-concentration organic wastewater.

Figure 8 shows the properties of high-concentration organic wastewater and low-concentration organic wastewater. High-concentration organic wastewater has a water temperature of 24°C, SS 500mg/L, COD _Cr 7,000mg/L, BOD 3,000mg/L, and NH ₄ -N 1,500mg/L. /L, COD _Cr 600 mg/L, BOD 150 mg/L, NH ₄ -N 54 mg/L. In the series of the comparative example, high-concentration organic waste water and low-concentration organic waste water were mixed and then water was passed through, and in the series of Example 2, only high-concentration organic waste water was passed.

FIG. 9 shows the amount of high-concentration organic wastewater, the amount of low-concentration organic wastewater, the BOD concentration of the influent, the water temperature in the reactor, and the occurrence of moth flies. Occurrence of moth flies was visually evaluated. In the comparative example, the influent BOD concentration was 1,580 mg/L, the water temperature in the reactor was 26 to 28° C., and the number of flies was ++ (many) to +++ (very many). On the other hand, in Example 2, the influent BOD concentration was 3,000 mg/L, the water temperature in the reactor was 32 to 34° C., and the occurrence of flies was + (few) to − (no occurrence). Thus, by maintaining the water temperature in the reactor at 30 to 40° C., it was possible to suppress the generation of fruit flies.

REFERENCE SIGNS LIST 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 carrier 21 Support 22d... Opening 22b... Extended part 22... Membrane 22a... Curved part 23... Space

Claims (9)

In an aerobic treatment apparatus for aerobically biologically treating one or more organic wastewaters,
An aerobic process that takes into account the water temperature of the organic wastewater, the amount of heat generated by the decomposition of BOD in the organic wastewater, the amount of heat generated by the nitrification of the organic wastewater, and the amount of heat generated by the operation of the mechanical equipment of the aerobic treatment apparatus. A heat balance calculation is performed within the processing apparatus, and based on the calculation result of the heat balance calculation, the heat is supplied into the aerobic processing apparatus so that the temperature in the aerobic processing apparatus is maintained at 15 to 40 ° C. A method for treating organic wastewater, comprising adjusting the supply flow rate of the organic wastewater. 2. The method for treating organic wastewater according to claim 1, comprising adjusting the BOD concentration and the ammonia nitrogen concentration in the aerobic treatment apparatus by adjusting the supply flow rate of the organic wastewater. Claim 1 or 2, comprising performing the heat balance calculation based on the following relational expressions (1) to (5) and determining the supply flow rate of the organic wastewater supplied to the aerobic treatment device 3. The method for treating organic wastewater according to .
X1 (Kcal/d) = supply flow rate (m ³ /d) × (treated water temperature (°C) - supply water temperature (°C)) × 0.001 (1)
Y1 (Kcal/d) = heat of biological reaction A per unit weight associated with BOD decomposition (Kcal/kg-BOD) x amount of BOD removed (kg-BOD/d) (2)
Y2 (Kcal/d) = Heat of biological reaction B per unit weight associated with nitrification (Kcal/kg-N) x NH ₄ -N nitrification amount (kg-N/d) (3)
Y3 (Kcal/d): calorific value associated with mechanical equipment operation of aerobic treatment equipment (4)
X1=(Y1+Y2+Y3)×α (5)
(α indicates the heat dissipation rate (-) from the aerobic treatment equipment) The aerobic treatment device is a trickling filter, and the supply flow rate of the organic wastewater is adjusted so that the temperature in the trickling filter is maintained at 30 to 40 ° C. The method for treating organic wastewater according to any one of items 1 and 2. The organic wastewater according to any one of claims 1 to 4, including that the volume ratio (liquid volume/gas volume) β of the gas and liquid in the aerobic treatment device is 0.2 or less. Processing method. The method for treating organic wastewater according to any one of claims 1 to 5, wherein the organic wastewater supplied to the aerobic treatment apparatus has a BOD concentration of 1000 to 10000 mg/L. An aerobic treatment apparatus for aerobic biological treatment of one or more organic wastewaters,
It is preferable to consider the water temperature of the organic wastewater, the calorific value associated with BOD decomposition of the organic wastewater, the calorific value associated with nitrification of the organic wastewater, and the calorific value associated with the operation of the mechanical equipment of the aerobic treatment apparatus. A heat balance calculation is performed in the aerobic treatment apparatus, and based on the calculation result of the heat balance calculation, the temperature in the aerobic treatment apparatus is maintained at 15 to 40 ° C. Supply to the aerobic treatment apparatus A treatment apparatus for organic wastewater, comprising 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;
Dilution rate determination means for determining a dilution rate of a diluent fluid for diluting the organic waste water based on the result of measuring the water temperature;
8. The organic wastewater treatment apparatus according to claim 7, further comprising a dilution fluid supply means for supplying the dilution fluid to the organic wastewater. The aerobic treatment device is a trickling filter,
wherein said flow rate adjusting means adjusts the supply amount of said organic waste water so that the temperature of said organic waste water in said trickling filter is adjusted to 30 to 40°C. The organic wastewater treatment device according to 7 or 8.

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