JP2006305555A - Apparatus and method for treating waste water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for treating waste water, in which high-concentration nitrogen-containing waste water and acidic waste water, particularly, fluorine-containing waste water can be treated combinedly and the running cost of which is reduced and to provide a method for treating waste water. <P>SOLUTION: In each of the apparatus and the method for treating waste water, the pH of the waste water to be treated is adjusted by adding the treated water treated at a nitrogen removing step being the succeeding step for removing nitrogen from waste water. It is preferable that the waste water to be treated is introduced into an anaerobic denitrification tank 3 and then into a nitrification tank 4 the waste water in which is aerated by an aeration unit 16 and the pH of fluorine-containing waste water is adjusted by using the treated water which is filtered by a submerged membrane 19 and sent from the nitrification tank 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wastewater treatment apparatus and a wastewater treatment method capable of treating high-concentration nitrogen wastewater and acidic wastewater, particularly fluorine-containing wastewater, in a complex manner.

  Since April 2004, the revised Water Pollution Control Law has been enforced, and the total amount of nitrogen emissions has been regulated. Fluorine must be 8 mg / L or less according to the release standard to rivers of the Water Pollution Control Law, and 0.8 mg / L or less according to the environmental standard. In addition, fluorine is designated as a Class 1 Designated Chemical Substance that requires notification by the PRTR (Pollutant Release and Transfer Register), and it is desirable to reduce planned emissions.

  Conventionally, as described in Patent Document 1 and Patent Document 2, wastewater is fed into a denitrification tank and a nitrification tank in order as a treatment method for wastewater containing ammonia nitrogen, and the wastewater is biologically treated in the denitrification tank. There is known a nitrification / denitrification method in which ammonia nitrogen or nitrite nitrogen that cannot be denitrified in a denitrification tank is oxidized and decomposed to nitrate nitrogen in a nitrification tank and returned to the denitrification tank.

  However, high-concentration nitrogen wastewater such as high-concentration ammonia wastewater is difficult to treat with microorganisms because of its toxicity, and it is necessary to concentrate it in an evaporator and treat the concentrate as industrial waste. High energy consumption when concentrating.

  In addition, as a method for removing fluorine in wastewater to 0.8 mg / L or less, Patent Document 3 describes a method for generating and separating apatite-based precipitates by adding calcium compounds and phosphoric acids to wastewater. ing.

In the method of Patent Document 3, the pH of the fluorine-containing wastewater needs to be 4 or more, preferably 6 or more, and an alkaline agent must be used for acidic wastewater.
Japanese Patent No. 3095620 Japanese Patent No. 3467671 Japanese Patent No. 3504248

  In semiconductor factories, a large amount of buffered hydrofluoric acid mixed with hydrofluoric acid and ammonium fluoride is used, and it is necessary to treat high-concentration nitrogen wastewater in addition to high-concentration nitrogen wastewater.

  Therefore, in view of the problems, an object of the present invention is to provide a wastewater treatment apparatus and a wastewater treatment method with low running cost that can treat high-concentration nitrogen wastewater and acidic wastewater, particularly fluorine-containing wastewater, in a complex manner.

  In order to solve the above problems, a wastewater treatment apparatus according to the present invention includes a pH adjustment tank that adjusts the pH of wastewater, and a nitrogen treatment apparatus that removes nitrogen from wastewater downstream of the pH adjustment tank. A part of the treated water treated by the apparatus is introduced into the pH adjusting tank.

  According to this structure, consumption of pH processing agents, such as an alkaline agent required for waste water treatment, is small, and it is economical.

  Further, in the wastewater treatment apparatus of the present invention, the nitrogen treatment apparatus comprises a denitrification tank that performs reductive decomposition by anaerobic microorganisms, and a nitrification tank that is aerated by an aeration apparatus and oxidatively decomposes by aerobic microorganisms. The tank may have a submerged membrane for filtering and discharging treated water.

  According to this configuration, the pH of the treated water discharged from the nitrification tank can be controlled between 6 and 9, and the pH of the raw waste water or the primary treated waste water can be adjusted.

  In the wastewater treatment apparatus of the present invention, the aeration apparatus may include a micro / nano bubble generation apparatus.

  According to this configuration, the micro / nano bubbles stay in the water for a long time and increase the oxygen concentration of the treated water, so that the aerobic microorganisms in the nitrification tank are activated. This improves the efficiency of oxidative decomposition of ammonia nitrogen and nitrite nitrogen in the nitrification tank of aerobic microorganisms.

  Further, in the wastewater treatment apparatus of the present invention, the nitrification tank is provided with the submerged film, and is an upper part constituting an aerobic part that is aerated by the aeration apparatus and a lower part of the aeration apparatus that is not aerated. It is good also as what consists of the lower part which comprises an anaerobic part, and the waste_water | drain of the said denitrification tank is introduce | transduced into the said semi-anaerobic part.

  According to this configuration, since the semi-anaerobic part is provided between the anaerobic denitrification tank and the aerobic part of the nitrification tank, the environmental change with respect to microorganisms is gentle, and the activity of microorganisms is actively maintained to maintain high concentration nitrogen. Effluent can be treated efficiently.

  Further, in the waste water treatment apparatus of the present invention, the bottom of the semi-anaerobic part has a hopper shape, and has a pump for returning sludge at the bottom of the semi-anaerobic part to the bottom of the denitrification tank, and contains nitrogen If wastewater is introduced into the bottom of the denitrification tank, when high-concentration microorganisms in the sludge at the bottom denitrify high-concentration nitrate nitrogen, there is less stress on the microorganisms and treatment efficiency increases. .

  Further, in the wastewater treatment apparatus of the present invention, if the aeration apparatus includes a micro-nano bubble generation apparatus installed in a bubble generation tank provided between the denitrification tank and the nitrification tank, the generation status of micro-nano bubbles is determined. Appropriate aeration can be performed according to the state of the wastewater while visually confirming it, so that various wastewater can be treated.

  Further, in the wastewater treatment apparatus of the present invention, if the submerged membrane is an ultrafiltration membrane, suspended matter that adversely affects the treatment of wastewater after pH adjustment is not included in the treated water.

  Further, in the wastewater treatment apparatus of the present invention, if treated water or biologically treated sludge is introduced into the denitrification tank, minerals necessary for the activity of microorganisms can be supplied, so that the treatment efficiency can be maintained high.

  Moreover, if the waste water treatment apparatus of this invention has a control means which controls the amount of aeration of the said aeration apparatus so that pH of the said nitrification tank may be kept alkaline, it can treat acidic waste water efficiently.

  Further, in the wastewater treatment apparatus of the present invention, when the pH of the pH adjustment tank is low, the pH of the nitrification tank becomes high if the aeration amount of the aeration apparatus is reduced. It can be adjusted to an appropriate value.

  Further, in the wastewater treatment apparatus of the present invention, when the flow rate of treated water treated by the nitrogen treatment apparatus decreases, if the aeration amount of the aeration apparatus is increased, the deposits in the submerged film are removed with air bubbles. In addition, since the clogging of the submerged membrane can be eliminated, the flow rate of the treated water can be secured.

  Further, in the wastewater treatment apparatus of the present invention, when the flow rate of the treated water treated by the nitrogen treatment apparatus is lowered, if the water level of the nitrification tank is increased, the discharge pressure of the treated water is increased due to the water head difference and the treated water is discharged. A flow rate can be secured.

  Further, in the wastewater treatment apparatus of the present invention, even if high-concentration ammonia-containing wastewater or development waste liquid is introduced into the nitrogen treatment apparatus, ammonia and nitrogen compounds in the treated water are treated with nitrogen in the denitrification tank and nitrification tank. it can.

  Moreover, the wastewater treatment apparatus of the present invention is a fluorine treatment apparatus in which wastewater containing fluorine is introduced into the pH adjusting tank, and fluorine in the wastewater whose pH is adjusted in the pH adjusting tank is separated as hardly soluble fluoride. The waste water treated by the fluorine treatment device may be introduced into the nitrogen treatment device.

  According to this configuration, since the mineral content remaining after removing the fluorine by adjusting the pH of the wastewater to an appropriate value is consumed by the microorganisms that remove nitrogen, wastewater containing fluorine and wastewater containing nitrogen are combined. Can be processed efficiently.

  In the wastewater treatment apparatus of the present invention, the fluorine treatment apparatus can efficiently treat fluorine as long as it is a crystallized substance reaction column filled with a poorly soluble fluorine-containing substance forming agent made of calcium phosphate salts, and further contains phosphoric acid. If a device for injecting a fluorine-insoluble substance forming auxiliary agent is provided, fluorine can be processed to a higher degree.

  Further, in the wastewater treatment apparatus of the present invention, the pH adjusting tank constitutes a part of a fluorine treatment apparatus that forms a poorly soluble fluoride by introducing a poorly soluble substance forming agent into the wastewater and separates fluorine from the wastewater. If wastewater treated by the fluorine treatment device is introduced into the nitrogen treatment device, wastewater containing high concentration of fluorine can be treated.

  Moreover, in the said fluorine treatment apparatus of the waste water treatment apparatus of this invention, if a fluorine poorly soluble substance formation adjuvant containing phosphoric acid is thrown in, fluorine can be removed more highly.

  Further, in the wastewater treatment apparatus of the present invention, if at least a part of the sparingly soluble fluoride separated by the fluorine treatment apparatus is introduced into the nitrogen treatment apparatus, the fluoride particles are in the submerged membrane of the nitrification tank. Prevent clogging.

  Further, in the wastewater treatment apparatus of the present invention, if the phosphorus removal apparatus capable of removing phosphorus from wastewater is provided, and the wastewater treated by the fluorine treatment apparatus is introduced into the nitrogen treatment apparatus via the phosphorus removal apparatus, the nitrogen An amount of phosphorus that cannot be consumed by the microorganisms in the treatment apparatus does not remain in the treated water.

  Further, in the wastewater treatment apparatus of the present invention, in the fluorine treatment apparatus, if a phosphorus compound is introduced so that the phosphorus concentration (weight conversion) is 1.2 times or more of the fluorine concentration, the fluorine remains in the apatite. Phosphorus can be a nutrient source for microorganisms in the nitrogen treatment apparatus.

  Moreover, in the waste water treatment apparatus of the present invention, the waste water introduced into the pH adjusting tank may be waste water containing buffered hydrofluoric acid or waste water after primary treatment of waste water containing buffered hydrofluoric acid. In addition, both fluorine and ammonia in wastewater can be treated in a complex manner.

  Moreover, the waste water treatment method by this invention adjusts the pH of the waste water which should be processed by adding the treated water processed by the nitrogen treatment process which removes nitrogen from the waste water which is a post process.

  According to this method, the consumption of a pH treating agent such as an alkaline agent required for wastewater treatment can be reduced, which is economical.

  In the wastewater treatment method of the present invention, the nitrogen treatment step is a step of sequentially introducing wastewater into an anaerobic denitrification tank and a nitrification tank that is aerated by an aeration apparatus, and the nitrification tank filters the treated water. Then, it may have a submerged membrane that is discharged.

  According to this method, the pH of the treated water discharged from the nitrification tank can be controlled between 6 and 9, and the pH of the raw water and the waste water subjected to the primary treatment can be adjusted.

  In the wastewater treatment method of the present invention, the aeration apparatus may include a micro / nano bubble generating apparatus.

  According to this configuration, the micro / nano bubbles stay in the water for a long time and increase the oxygen concentration of the treated water, so that the aerobic microorganisms in the nitrification tank are activated. This improves the efficiency of oxidative decomposition of ammonia nitrogen and nitrite nitrogen in the nitrification tank of aerobic microorganisms.

  Moreover, in the wastewater treatment method of the present invention, the aeration apparatus includes a micro / nano bubble generation apparatus installed in a bubble generation tank provided between the denitrification tank and the nitrification tank, and the aeration is performed in the denitrification tank. If the wastewater is introduced into the bubble generation tank and micronanobubbles are generated in the wastewater by the micronanobubble generator and then introduced into the nitrification tank, the state of the wastewater is confirmed while visually confirming the micronanobubble generation status. Because it can be operated according to the situation, it can treat a variety of wastewater.

  Further, in the wastewater treatment method of the present invention, if the aeration amount of the aeration apparatus is controlled so as to keep the pH of the nitrification tank alkaline, an alkaline agent for neutralizing acidic wastewater can be saved.

  In the wastewater treatment method of the present invention, when the pH of the wastewater to be treated is low, if the aeration amount of the aeration apparatus is reduced, the pH of the nitrification tank is increased, so that the amount of treated water to be introduced is reduced. The amount of wastewater to be treated is not more than necessary.

  Further, in the wastewater treatment method of the present invention, the wastewater whose pH has been adjusted is introduced into the denitrification tank after being treated in a fluorine treatment step of separating the hardly soluble fluoride formed by introducing a poorly soluble substance forming agent. For example, both fluorine and nitrogen can be removed.

  Moreover, in the said fluorine treatment process of the waste water treatment method of this invention, if the fluorine poorly soluble substance formation adjuvant containing phosphoric acid is thrown in, a fluorine can be processed highly.

  Further, in the wastewater treatment method of the present invention, in the fluorine difficult treatment step, a phosphorus compound is added so that the phosphorus concentration (weight conversion) is 1.2 times or more of the fluorine concentration, and residual phosphorus is removed from the nitrogen treatment step. If it is consumed by microorganisms, high fluorine treatment and highly efficient nitrogen treatment can be realized.

  Further, in the wastewater treatment method of the present invention, if a part of the hardly soluble fluoride separated in the fluorine treatment step is introduced into the denitrification tank or the nitrification tank, the fluoride particles are formed in the submerged membrane of the nitrification tank. Prevent clogging.

  Further, in the wastewater treatment method of the present invention, the nitrification tank is provided with the submerged membrane and is located above the upper part of the aerobic part to be aerated by the aeration apparatus and below the aeration apparatus and is not aerated. If the waste water from the denitrification tank is introduced into the semi-anaerobic part, the environmental change with respect to microorganisms is moderate, and the active activity of microorganisms can be maintained and the efficiency of nitrogen treatment can be increased. .

  Further, in the wastewater treatment method of the present invention, the bottom of the semi-anaerobic part has a hopper shape, and if the sludge at the bottom of the semi-anaerobic part is returned to the bottom of the denitrification tank, high-concentration microorganisms in the sludge Denitrifies high-concentration nitrogen compounds, reducing the stress of microorganisms and increasing the treatment efficiency.

  Further, in the wastewater treatment method of the present invention, if high-concentration nitrogen wastewater and biologically treated water or biologically treated sludge are introduced into the denitrification tank in addition to the treated water treated by the fluorine treatment apparatus, microorganisms Since the minerals necessary for this activity can be supplied, the treatment efficiency of the nitrogen treatment device can be maintained high.

  As described above, according to the present invention, since heat treatment is not performed, the energy consumption is small, and the pH of the waste water before treatment is adjusted with the treated water after treatment, so that the consumption of the alkaline agent is small and the running cost is low. Further, according to the present invention, comprehensive efficiency and advanced treatment of wastewater treatment can be realized.

From this, the waste water treatment apparatus and waste water treatment method by this invention are demonstrated, showing embodiment.
FIG. 1 is a flow sheet of the waste water treatment apparatus according to the first embodiment of the present invention. The wastewater treatment apparatus of this embodiment is a nitrogen treatment apparatus 5 comprising a fluorine-based raw water tank (pH adjustment tank) 1 that receives fluorine-containing wastewater and adjusts pH, a fluorine treatment apparatus 2, a denitrification tank 3, and a nitrification tank 4. It is made up of.

  Fluorine-containing wastewater such as buffered hydrofluoric acid waste liquid is introduced into the pH adjustment tank 1. The pH adjusting tank 1 is provided with a stirrer 6 and a pH meter 7 for measuring the pH of the waste water. The wastewater stored in the pH adjustment tank 1 is drawn out by the pump 8 and sent to the fluorine treatment apparatus 2.

  The fluorine treatment apparatus 2 is a crystallized product reaction tower filled with granular calcium phosphate salts, and a hardly soluble substance forming auxiliary agent tank 9 in which a fluorine hardly soluble substance forming auxiliary agent made of an acid containing phosphoric acid is stored. And a poorly soluble substance formation auxiliary agent injection pump 10 for injecting a fluorine poorly soluble substance formation auxiliary agent from the hardly soluble substance formation auxiliary agent tank 9 into the crystallized product reaction tower 2. Waste water flowing out from the crystallized product reaction tower 2 is introduced into the denitrification tank 3.

  In the denitrification tank 3, in addition to the wastewater treated in the crystallized product reaction tower 2, high-concentration nitrogen drainage such as waste liquid containing a high concentration of ammonia and development waste liquid, and biologically treated treated water such as treated water in the joint septic tank Alternatively, biological treatment sludge and aminoethanol-containing wastewater are introduced. The denitrification tank 3 includes a stirrer 11, but oxygen is not supplied, and anaerobic microorganisms (denitrification bacteria) are propagated. Waste water overflowed from the denitrification tank 3 flows into the bottom of the nitrification tank 4 through the communication pipe 12.

  In the nitrification tank 4, the movement of the drainage is restricted by the separation wall 13 and is divided into an upper aerobic part 14 and a lower semi-anaerobic part 15. The aerobic unit 14 is provided with an aeration device 16, and the air sent from the blower 17 is discharged into the liquid and supplied with oxygen. Further, the air lift pump 18 using the air from the blower 17 returns the sludge that precipitates at the bottom of the semi-anaerobic portion 15 of the nitrification tank 4 to the denitrification tank 3. Further, the aerobic part 14 of the nitrification tank 4 is provided with a submerged film 19 made of an ultrafiltration membrane, and the water to be treated staying in the aerobic part 14 is filtered and suspended solids and microorganisms are removed. The treated water is discharged by gravity or by the pump 20 via the flow meter 21. The treated water extracted by the pump 22 through the submerged film 19 is introduced into the pH adjustment tank 1.

Subsequently, a treatment operation of the wastewater treatment apparatus having the above configuration will be described.
The fluorine-containing wastewater introduced into the pH adjusting tank 1 is acidic, but is adjusted to pH 6.5 to 8.5 in the pH adjusting tank 1. Since the treated water in the nitrification tank 4 of the nitrogen treatment apparatus 5 that treats high-concentration nitrogen wastewater exhibits an alkaline property of about pH 9 due to ammonia nitrogen, the pH adjustment of the wastewater in the pH adjustment tank 1 is performed by the pump 22 in the treatment of the nitrification tank 4. This is realized by introducing water into the pH adjustment tank 1. Of course, an alkali agent may be used in combination.

  The wastewater whose pH is adjusted in the pH adjusting tank 1 is sent to the crystallized product reaction tower 2 by the pump 8. The fluorine in the waste water into which the fluorine poorly soluble substance forming auxiliary agent containing phosphoric acid has been previously injected by the poorly soluble substance forming auxiliary agent injection pump 10 is the fluorine poorly soluble substance forming agent filled in the crystallized substance reaction tower 2. To form a fluorine poorly soluble substance (apatite, which is a poorly soluble fluoride combined with phosphorus and calcium). As a result of the poorly fluorine-soluble substance growing on the surface of the fluorine-insoluble substance forming agent, fluorine in the waste water is removed inside the crystallized product reaction tower 2.

  The amount of the poorly soluble substance formation auxiliary agent injected by the hardly soluble substance formation auxiliary agent injection pump 10 is determined so that the phosphorus concentration (weight conversion) is 1.2 times or more the fluorine concentration. This amount means that the phosphorus concentration is higher than that consumed in the crystallized product reaction tower 2 when all the fluorine in the wastewater is fixed to the hardly soluble substance. As a result, formation of a fluorine-insoluble substance can be promoted to the maximum, and fluorine can be highly removed.

  The waste water from which the fluorine has been removed is introduced into the denitrification tank 3 of the nitrogen treatment device 5. Further, high-concentration nitrogen wastewater, biologically treated water or biologically treated sludge, and aminoethanol-containing wastewater are introduced into the denitrification tank 3.

  In the denitrification tank 3, all the oxygen in the waste water is consumed, and denitrifying bacteria that are anaerobic microorganisms grow. Anaerobic microorganisms use nitrogen remaining in the effluent while consuming the phosphorus contained in the crystallized substance reaction tower 2 without being fixed together with fluorine and the minerals contained in the biologically treated water or biologically treated sludge as nutrients. Reduce to gas. That is, by injecting a fluorine-insoluble substance forming auxiliary agent in excess of the amount necessary for removing fluorine contained in the crystallized product reaction tower 2, it is possible to add nutrients necessary for the activity of anaerobic microorganisms. Reduction of nitrogen in the nitrogen tank 3 can be promoted.

  In addition, aminoethanol contained in the wastewater containing aminoethanol discharged at the semiconductor factory acts as a hydrogen donor necessary for the activity of anaerobic microorganisms, but methanol may be used if there is no wastewater containing aminoethanol.

  In the denitrification tank 3, organic substances other than nitrogen are also biochemically decomposed by anaerobic microorganisms. However, anaerobic microorganisms cannot decompose only ammonia nitrogen, and waste water containing ammonia nitrogen overflows from the denitrification tank 3 and is introduced into the semi-anaerobic portion 15 of the nitrification tank 4 through the communication pipe 12. The

  The semi-anaerobic part 15 of the nitrification tank 4 is slightly supplied with oxygen from the aerobic part 14 supplied with oxygen by the aeration device 16 and contains 0.5 ppm or less of dissolved oxygen. Under this condition, the anaerobic microorganisms supplied from the denitrification tank 3 are not exposed to a rapid environmental change, so that the activity is not extremely reduced. The sludge having a high concentration of anaerobic microorganisms precipitated at the bottom of the nitrification tank 5 is returned to the denitrification tank 3 by the air lift pump 18 while maintaining the activity. At this time, the amount of oxygen supplied by the air lift pump 18 is small compared to the amount of microorganisms and is consumed immediately, so that the dissolved oxygen in the denitrification tank 3 does not increase.

  In the aerobic section 14, nitrification is performed by oxidizing and decomposing ammoniacal nitrogen into nitrate nitrogen by aeration of the aeration device 16. Nitrified nitrate nitrogen is returned to the denitrification tank 3 together with sludge by an air lift pump 18 and reduced to nitrogen gas by anaerobic microorganisms.

  Moreover, the treated water filtered by the submerged membrane 19 in the aerobic part 14 of the nitrification tank 5 is sent to the next treatment process through the flowmeter 21 by its own weight. However, when the opening of the submerged film 19 is clogged with microorganisms or insoluble suspended matter, the amount of treated water flowing out decreases. Therefore, an appropriate flow rate of treated water is ensured by using a forced filtration discharge by the pump 20 together.

  As described above, the nitrification tank 4 tends to be alkaline because it contains ammonia nitrogen supplied from the denitrification tank 3. Although it tends to be acidic when it is oxidatively decomposed into nitrate nitrogen by aeration of the aeration device 16, the treated water supplied to the pH adjusting tank 1 by the pump 22 is alkaline under normal conditions, so that acidic fluorine-containing wastewater is contained in the inside. Convenient to reconcile.

  In FIG. 2, the timing chart of the waste water treatment of this embodiment is shown. FIG. 2 shows that the fluorine concentration of the fluorine-containing wastewater stored in the pH adjusting tank 1 is 6 ppm, the wastewater from the crystallized substance reaction tower (fluorine treatment device) 2 introduced into the denitrification tank 3, and the high-concentration nitrogen wastewater. The case where the total nitrogen concentration of the biologically treated treated water or the biologically treated sludge and the aminoethanol-containing wastewater is 46 ppm is shown.

  The pH of the fluorine-containing wastewater is adjusted in a pH adjusting tank (raw water tank) 1, and the residence time here is about 1 hour. The pump 8 is driven so that the wastewater passes through the crystallized product reaction tower 2 in about 1 hour, and fluorine in the wastewater is removed while passing through the crystallized product reaction tower 2. Waste water from the crystallized product reaction tower 2, high-concentration nitrogen waste water, treated water or biologically treated sludge is decomposed by circulating through the denitrification tank 3 and the nitrification tank 4, but the denitrification tank 3 and the nitrification tank 4 The average residence time at is about 4 hours and about 8 hours, respectively.

  FIG. 3 shows that the fluorine concentration of the fluorine-containing wastewater stored in the pH adjusting tank 1 is 12 ppm, the wastewater from the crystallized substance reaction tower (fluorine treatment device) 2 introduced into the denitrification tank 3, and the high-concentration nitrogen wastewater. The case where the total nitrogen concentration of the biologically treated treated water or the biologically treated sludge and the aminoethanol-containing wastewater is 92 ppm is shown.

  The fluorine-containing wastewater stays for about 2 hours in order to stabilize the water quality in the pH adjusting tank 1 and passes through the crystallized product reaction tower 2 over about 4 hours. The average residence times in the denitrification tank 3 and the nitrification tank 4 into which the waste water from the crystallized product reaction tower 2, high-concentration nitrogen waste water, biologically treated water or biologically treated sludge are introduced are about 8 hours and about 16 hours, respectively. It is.

  Since there is an upper limit on the amount of fluorine and nitrogen that can be removed per hour by the waste water treatment device, as shown in FIGS. 2 and 3, the residence time of the waste water is set in proportion to the fluorine concentration and nitrogen concentration of the waste water, that is, the flow rate. Need to be changed.

  Next, FIG. 4 shows a second embodiment of the present invention. Hereinafter, the same components as those in the above embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, high-concentration nitrogen wastewater, biologically treated water and domestic sludge are stored once in the nitrogen-based raw water tank 23 and supplied to the bottom of the denitrification tank 3 by the pump 25.

  A filling 26 made of vinylidene chloride is disposed in the denitrification tank 3 and the nitrification tank 4 of the nitrogen treatment apparatus 5. A dedicated blower 27 is provided for the air lift pump 18. Furthermore, the nitrification tank 4 includes a pH meter 28 that measures the pH of the aerobic part 14.

  Further, the waste water discharged from the crystallized product reaction tower 2 is introduced into the denitrification tank 3 through the phosphorus poorly soluble substance forming tank 29.

  In the present embodiment, the raw water is homogenized by the nitrogen-based raw water tank 23 and the supply amount to the nitrogen treatment device 5 can be adjusted. Thereby, in order to ensure the said appropriate residence time of the waste_water | drain in the nitrogen treatment apparatus 5, an introduction amount can be adjusted, a process condition does not fluctuate by increase / decrease in a waste_water | drain amount, and stable nitrogen removal is possible. In addition, microorganisms adhere to and propagate in the filling 26 of the denitrification tank 3 and the nitrification tank 4, and the microorganisms in the nitrogen treatment apparatus 5 become a high concentration as a whole, so that the wastewater treatment capacity is improved.

  Moreover, this embodiment is provided with the control means which controls the output of the blower 17 in order to adjust the amount of aeration so that pH of the aerobic part of the nitrification tank 4 may be maintained at 9.0. If the amount of aeration is increased, the oxidative decomposition of ammonia nitrogen to nitrate nitrogen can be promoted and the alkalinity can be lowered. If the capacity of the aeration device 16 is sufficiently large, ammonia nitrogen is decomposed into nitrate nitrogen. It is also possible to acidify to about pH 5.

  When the fluorine-containing wastewater contains a large amount of phosphorus from the beginning, the phosphorus-poorly soluble substance forming tank 29 prevents the phosphorus content consumed by microorganisms in the nitrogen treatment apparatus 5 from being formed. The poorly soluble phosphorus compound that precipitates when the agent is added can be extracted. This can prevent phosphorus from remaining in the treated water and flowing to the subsequent process.

FIG. 5 shows a third embodiment of the present invention.
This embodiment is the same as the apparatus provided with the nitrogen-based raw water tank 23 of FIG. 4 in the first embodiment of FIG. 1 except as noted below. The semi-anaerobic part 15 of the nitrification tank 4 has a conical hopper shape, and the sludge at the bottom of the semi-anaerobic part 15 is returned to the bottom of the denitrification tank 3 by an electric pump 30. The nitrification tank 4 has a level switch 31 for detecting the water level.

  In the present embodiment, when the submerged film 19 is clogged and the flow rate of the treated water from the nitrification tank 4 is reduced, the aeration amount of the aeration apparatus 16 provided immediately below the submerged film 19 is increased. Increase the output of the blower 17. As a result, microorganisms and insoluble suspended matters adhering to the surface of the submerged film 19 are removed by air bubbles.

  Even if the flow rate of the treated water cannot be ensured, the discharge amount of the pump 30 can be reduced so that the liquid level of the nitrification tank 4 is increased, and the flow rate of the treated water can be ensured by the water head difference.

  Further, due to the conical hopper shape of the semi-anaerobic portion 15, the sludge having the highest microorganism concentration can be returned to the denitrification tank 3. Further, by returning the sludge to the bottom of the denitrification tank 3, both the nitrogen concentration and the microorganism concentration in the denitrification tank 3 become higher in the lower part. For this reason, since there is no variation in the amount of nitrogen to be decomposed by each anaerobic microorganism, the activity is maintained with a small load fluctuation stress on the anaerobic microorganism.

FIG. 6 shows a fourth embodiment of the present invention.
This embodiment is the same as the third embodiment of FIG. 5 except as noted below. In the present embodiment, the fluorine-containing waste water is treated from the fluorine-based raw water tank 32 to the nitrogen treatment apparatus 5 after being treated by the fluorine treatment apparatus 36 including the fluorine hardly soluble substance forming tank 33, the aggregation tank 34, and the precipitation tank 35. be introduced. In the fluorine poorly soluble substance forming tank 33, the fluorine hardly soluble substance forming agent is charged and stirred by the stirrer 37, and the fluorine in the waste water is fixed to the hardly soluble substance such as apatite to become a suspension of the hardly soluble substance. .

  When this suspension overflows into the agglomeration tank (pH adjustment tank) 34 and a polymer flocculant is added and stirred by the stirrer 38, the hardly soluble substance aggregates to form large particle flocs. Further, the pH is adjusted with the treated water in the nitrification tank 4 based on the detection result of the pH meter 39. And the waste_water | drain from which the fluorine was removed is introduce | transduced into the denitrification tank 3 by carrying out precipitation separation in the precipitation tank 35 which has the scraping apparatus 40.

  Here, when calcium and phosphorus are contained in the fluorine-containing wastewater, the fluorine-insoluble substance forming agent has a composition that supplements calcium and phosphorus necessary for fixing fluorine in the wastewater to the apatite.

  The floc slurry precipitated in the settling tank 35 is pulled out by the pump 41, and a part thereof is introduced into the denitrification tank 3 and the hardly soluble substance forming tank 33.

  The fluorine treatment apparatus of the present embodiment has a simple apparatus configuration, a low initial cost, can remove more fluorine than a crystallized substance reaction tower with a long packing life, and can replace the packing. Since there is no running cost.

  The floc introduced into the denitrification tank 3 circulates between the nitrification tank 4, but the particles are large and prevent microbial sludge and insoluble suspended matter from adhering to the submerged membrane 19, It has the effect of scraping off sludge and insoluble suspended solids. The floc may be introduced into the nitrification tank 4 instead of the denitrification tank 3.

  Further, the floc introduced into the hardly soluble substance forming tank 33 becomes a nucleus when the fluorine hardly soluble substance is formed, and has an action of promoting the formation of the hardly soluble substance.

  Further, the floc of the extracted slurry is a recyclable substance.

  In the present embodiment, the pH of the raw water tank 32 and the hardly soluble substance forming tank 33 may be adjusted with the treated water of the nitrification tank 4.

  Moreover, in this embodiment, the output of the blower 17 is made low so that the aeration amount of the aeration apparatus 16 decreases as the pH of the pH adjustment tank (aggregation tank) 34 decreases. By reducing the amount of aeration in the nitrification tank 4, the ability to decompose ammonia nitrogen into nitrate nitrogen decreases, and the pH of the nitrification tank 4 increases. As a result, the increase or decrease in the amount of treated water necessary for neutralizing the wastewater in the pH adjustment tank 34 is alleviated, and stable fluorine removal becomes possible.

FIG. 7 shows a fifth embodiment of the present invention.
This embodiment is the same as the third embodiment of FIG. 5 except as noted below. In the present embodiment, the fluorine-containing wastewater is firstly treated by the fluorine primary treatment device 47 including the hardly soluble substance forming aggregation tank 45 and the precipitation tank 46 and then stored in the pH adjusting tank 1. In the hardly soluble substance agglomeration tank 45, the hardly soluble substance forming agent and the polymer flocculant are charged while stirring with the stirrer 48 to fix the fluorine to the hardly soluble substance. Then, the precipitate is separated in the precipitation tank 46, the pH is adjusted in the pH adjustment tank 1, and fluorine is further removed in the crystallized product reaction tower 2.

  In this embodiment, since the fluorine-containing waste water is firstly treated and then treated in the crystallization product reaction tower 2, the crystallization product reaction tower 2 can remove fluorine to a higher degree, but the initial cost and running cost are high. The processing capacity of 2 is small. For this reason, even when a large amount of wastewater containing high-concentration fluorine is discharged, fluorine can be treated at low cost with inexpensive equipment.

FIG. 8 shows a sixth embodiment of the present invention.
In this embodiment, the aerobic part 14 of the nitrification tank 4 of the first embodiment of FIG. 1 is further provided with a micro / nano bubble generator 51 as a second aeration device. The micro / nano bubble generator 51 includes a micro / nano bubble generator 52, a pump 53, and a regulating valve 54. When the treated water of the aerobic part 14 is injected by the pump 53, the micro / nano bubble generator 52 self-supplies air through the regulating valve 54 due to the negative pressure generated by the flow rate of the treated water, and the air is generated by the treated water flow. Is generated to generate micro-nano bubbles which are fine bubbles, and treated water containing the micro-nano bubbles is discharged.

  Since the micro / nano bubbles stay in the treated water for a long time without immediately rising to the water surface, the dissolved oxygen concentration in the aerobic part can be increased. As a result, aerobic microorganisms can be activated, and sufficient oxidative decomposition can be performed in the nitrification tank 4 even when wastewater containing particularly high concentrations of ammonia nitrogen and nitrite nitrogen is treated. .

  In the present embodiment, the aeration device 16 is used exclusively for removing microorganisms and insoluble suspended matters adhering to the submerged membrane 19, and the role of supplying oxygen for aerobic microorganisms is mainly the generation of micro-nano bubbles. Device 51. Moreover, in this embodiment, if the opening degree of the regulating valve 54 is adjusted according to the state of waste water, the dissolved oxygen concentration can be maintained at an optimum concentration by changing the amount of micro-nano bubbles generated.

FIG. 9 shows a seventh embodiment of the present invention.
In the present embodiment, the separation wall 13 is eliminated from the nitrification tank 4 of the sixth embodiment of FIG. It has the composition to have. Moreover, the waste water treatment apparatus of this embodiment includes a pH meter 28 that measures the pH of the treated water in the nitrification tank 4, and a pump 53 that injects the treated water into the micro / nano bubble generator 52 according to the pH of the nitrification tank 4. Can be started and stopped.

  In the present embodiment, as in the second embodiment of FIG. 4, the aeration amount is adjusted to maintain the pH of the treated water in the nitrification tank 4 at about 9.0, and acidic fluorine-containing wastewater is effective in the pH adjustment tank 1. Neutralize. Further, as shown in the present embodiment, in the present invention, it is not always essential to form the semi-anaerobic portion 15 in the nitrification tank 4, but in this case, in order to withstand a rapid change in oxygen concentration, It is desirable to increase the concentration.

FIG. 10 shows an eighth embodiment of the present invention.
In this embodiment, the micro / nano bubble generator 51 of the seventh embodiment of FIG. 9 is arranged in a small-capacity bubble generator tank 55 provided between the denitrification tank 3 and the nitrification tank 4. In this embodiment, the waste water overflowed from the denitrification tank 3 is temporarily stored in the bubble generation tank 55, and the waste water in the bubble generation tank 55 is extracted by the pump 53 and disposed in the bubble generation tank 55. The micro / nano bubble generator 52 is self-supplied with air via the regulating valve 54 to generate micro / nano bubbles. In this way, the waste water in the bubble generation tank 55 containing micro / nano bubbles is introduced into the bottom of the nitrification tank 4 by the pump 56, whereby the nitrification tank 4 is aerated.

  Since the micro / nano bubble generator 52 shears air with a water flow, the micro / nano bubble may not be generated properly when the state of the air and the water flow changes. In the present embodiment, since micro-nano bubbles are generated in the small-capacity bubble generation tank 55, the micro-nano bubbles discharged from the micro-nano bubble generator 52 can be directly visually confirmed. That is, various wastewater can be treated by adjusting the generation amount of micro / nano bubbles while the operator confirms according to the state of wastewater.

The flow sheet of the waste water treatment equipment of a 1st embodiment of the present invention. The example of the time chart of the driving | operation of the waste water treatment apparatus of FIG. The example of the time chart of the driving | operation in the different conditions of the waste water treatment equipment of FIG. The flow sheet of the waste water treatment equipment of a 2nd embodiment of the present invention. The flow sheet of the waste water treatment equipment of a 3rd embodiment of the present invention. The flow sheet of the waste water treatment equipment of a 4th embodiment of the present invention. The flow sheet of the waste water treatment equipment of a 5th embodiment of the present invention. The flow sheet of the waste water treatment equipment of a 6th embodiment of the present invention. The flow sheet of the waste water treatment equipment of a 7th embodiment of the present invention. The flow sheet of the waste water treatment equipment of an 8th embodiment of the present invention.

Explanation of symbols

1 Raw water tank (pH adjustment tank)
2 Crystallized product reaction tower (fluorine treatment equipment)
DESCRIPTION OF SYMBOLS 3 Denitrification tank 4 Nitrification tank 5 Nitrogen treatment apparatus 7 pH meter 10 Poorly soluble substance formation auxiliary agent injection pump 13 Separation wall 14 Aerobic part 15 Semi-anaerobic part 16 Aeration apparatus 18 Air lift pump 19 Submerged membrane (ultrafiltration membrane)
21 Flow meter 26 pH meter 29 Phosphorus poorly soluble substance formation tank (phosphorus removal device)
31 Level switch 33 Slightly soluble substance formation tank 34 Coagulation tank (pH adjustment tank)
35 Precipitation tank 36 Fluorine treatment device 45 Fluorine insoluble substance formation coagulation tank 46 Precipitation tank 47 Fluorine primary treatment device 51 Micro-nano bubble generator (aeration device)
55 Bubble generation tank

Claims (36)

A pH adjusting tank for adjusting the pH of the waste water, and a nitrogen treatment device for removing nitrogen from the waste water downstream of the pH adjusting tank,
A wastewater treatment apparatus, wherein a part of treated water treated by the nitrogen treatment apparatus is introduced into the pH adjustment tank. The nitrogen treatment apparatus comprises a denitrification tank that performs biochemical decomposition by anaerobic microorganisms, and a nitrification tank that is aerated by an aeration apparatus and oxidatively decomposes by aerobic microorganisms,
The waste water treatment apparatus according to claim 1, wherein the nitrification tank has a submerged membrane for filtering and discharging treated water.   The waste water treatment apparatus according to claim 2, wherein the aeration apparatus includes a micro / nano bubble generation apparatus. The nitrification tank is provided with the submerged membrane, and constitutes an aerobic part that is aerated by the aeration apparatus,
It consists of a lower part constituting a semi-anaerobic part below the aeration apparatus and not aerated,
The wastewater treatment apparatus according to claim 2 or 3, wherein wastewater from the denitrification tank is introduced into the semi-anaerobic part. The bottom part of the semi-anaerobic part has a hopper shape,
A pump that returns the sludge at the bottom of the semi-anaerobic part to the bottom of the denitrification tank;
The waste water treatment apparatus according to claim 4, wherein waste water containing nitrogen is introduced into a bottom of the denitrification tank.   The waste water treatment apparatus according to claim 2, wherein the aeration apparatus includes a micro / nano bubble generation apparatus installed in a bubble generation tank provided between the denitrification tank and the nitrification tank.   The wastewater treatment apparatus according to any one of claims 2 to 6, wherein the submerged membrane is an ultrafiltration membrane.   The wastewater treatment apparatus according to any one of claims 2 to 7, wherein biologically treated water or biologically treated sludge is introduced into the denitrification tank.   The wastewater treatment apparatus according to any one of claims 2 to 8, further comprising control means for controlling an aeration amount of the aeration apparatus so as to keep a pH of the nitrification tank alkaline.   The wastewater treatment apparatus according to any one of claims 2 to 8, wherein when the pH of the pH adjustment tank is low, an aeration amount of the aeration apparatus is reduced.   The wastewater treatment apparatus according to any one of claims 2 to 8, wherein when the flow rate of treated water treated by the nitrogen treatment apparatus decreases, the aeration amount of the aeration apparatus is increased.   The wastewater treatment apparatus according to any one of claims 2 to 11, wherein when the flow rate of treated water treated by the nitrogen treatment apparatus decreases, the water level of the nitrification tank is increased. The wastewater treatment apparatus according to any one of claims 2 to 12, wherein wastewater containing high-concentration ammonia is introduced into the nitrogen treatment apparatus.   The wastewater treatment apparatus according to any one of claims 2 to 12, wherein a developing waste liquid is introduced into the nitrogen treatment apparatus. Wastewater containing fluorine is introduced into the pH adjustment tank,
A fluorine treatment device that separates fluorine in the wastewater whose pH is adjusted in the pH adjustment tank as sparingly soluble fluoride,
The wastewater treatment apparatus according to any one of claims 1 to 14, wherein the wastewater treated by the fluorine treatment apparatus is introduced into the nitrogen treatment apparatus.   The wastewater treatment apparatus according to claim 15, wherein the fluorine treatment apparatus is a crystallized substance reaction tower filled with a fluorine poorly soluble substance forming agent made of calcium phosphate salts.   The wastewater treatment apparatus according to claim 15, wherein the crystallized product reaction tower has a device for injecting a fluorine-insoluble substance forming auxiliary agent containing phosphoric acid. The pH adjustment tank is a water tank that forms a part of a fluorine treatment apparatus that forms a poorly soluble fluoride by introducing a poorly soluble substance forming agent into the wastewater, and separates fluorine from the wastewater,
The wastewater treatment apparatus according to claim 15, wherein the wastewater treated by the fluorine treatment apparatus is introduced into the nitrogen treatment apparatus.   19. The wastewater treatment apparatus according to claim 18, wherein in the fluorine treatment apparatus, a fluorine poorly soluble substance forming auxiliary agent containing phosphoric acid is introduced.   The wastewater treatment apparatus according to claim 18 or 19, wherein at least a part of the hardly soluble fluoride separated by the fluorine treatment apparatus is introduced into the nitrogen treatment apparatus. Equipped with a phosphorus removal device that can remove phosphorus from wastewater,
The wastewater treatment apparatus according to any one of claims 15 to 20, wherein the wastewater treated by the fluorine treatment apparatus is introduced into the nitrogen treatment apparatus through the phosphorus removal apparatus.   The phosphorus treatment apparatus according to any one of claims 15 to 21, wherein in the fluorine treatment apparatus, a phosphorus compound is added so that a phosphorus concentration (weight conversion) in waste water is 1.2 times or more of a fluorine concentration. Wastewater treatment equipment.   23. The waste water introduced into the pH adjusting tank is waste water containing buffered hydrofluoric acid or waste water obtained by first treating waste water containing buffered hydrofluoric acid. The waste water treatment apparatus as described.   A wastewater treatment method characterized in that the pH of wastewater to be treated is adjusted by adding treated water treated in a nitrogen treatment step of removing nitrogen from wastewater as a subsequent step. The nitrogen treatment step is a step of sequentially introducing wastewater into a denitrification tank that performs biochemical decomposition by anaerobic microorganisms and a nitrification tank that is aerated by an aeration apparatus and oxidatively decomposes by aerobic microorganisms,
The waste water treatment method according to claim 24, wherein the nitrification tank has a submerged membrane for filtering and discharging treated water.   26. The waste water treatment method according to claim 25, wherein the aeration apparatus includes a micro / nano bubble generator installed in the nitrification tank. The aeration apparatus includes a micro / nano bubble generation apparatus installed in a bubble generation tank provided between the denitrification tank and the nitrification tank,
The aeration is performed by introducing waste water from the denitrification tank into the bubble generation tank, generating micro / nano bubbles in the waste water by the micro / nano bubble generation apparatus, and then introducing the micro / nano bubbles into the nitrification tank. The wastewater treatment method according to 25.   The wastewater treatment method according to any one of claims 25 to 27, wherein the aeration amount by the aeration apparatus is controlled so as to keep the pH of the nitrification tank alkaline.   The wastewater treatment method according to any one of claims 25 to 27, wherein when the pH of the wastewater to be treated is low, the aeration amount of the aeration apparatus is reduced.   30. The method according to claim 25, wherein the pH-adjusted wastewater is introduced into the denitrification tank after being treated in a fluorine treatment step for separating the hardly soluble fluoride formed by introducing a poorly soluble substance-forming agent. The waste water treatment method in any one of.   The wastewater treatment method according to claim 30, wherein, in the fluorine treatment step, a fluorine poorly soluble substance forming auxiliary agent containing phosphoric acid is added.   In the fluorine treatment step, a phosphorus compound is added so that the phosphorus concentration (weight conversion) is 1.2 times or more of the fluorine concentration, and the remaining phosphorus is consumed by microorganisms in the nitrogen treatment step. Item 32. The wastewater treatment method according to Item 30 or 31.   The wastewater treatment method according to any one of claims 30 to 32, wherein a part of the hardly soluble fluoride separated in the fluorine treatment step is introduced into the denitrification tank or the nitrification tank. The nitrification tank is provided with the submerged membrane, and an upper part constituting an aerobic part to be aerated by the aeration apparatus,
It consists of a lower part constituting a semi-anaerobic part below the aeration apparatus and not aerated,
The wastewater treatment method according to any one of claims 25 to 33, wherein wastewater from the denitrification tank is introduced into the semi-anaerobic part. The bottom part of the semi-anaerobic part has a hopper shape,
The wastewater treatment method according to claim 34, wherein sludge at the bottom of the semi-anaerobic part is returned to the bottom of the denitrification tank.   36. The high concentration nitrogen waste water and the biologically treated water or the biologically treated sludge are introduced into the denitrification tank in addition to the waste water treated in the fluorine treatment step. The described waste water treatment method.

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