JP6538537B2 - Nitrification denitrification equipment - Google Patents

Description

  Embodiments of the present invention relate to a nitrification denitrification apparatus that performs nitrification denitrification of water to be treated using a carrier that supports bacteria.

  As a water treatment process for removing organic substances contained in various waste water and the like, there is a method of performing anaerobic treatment using methane bacteria, without using conventional organic matter oxidizing bacteria. The methane bacteria are anaerobic bacteria, and nitrite denitrifying bacteria and nitrate denitrifying bacteria used in the denitrification reaction are also anaerobic bacteria. From such similarity of bacteria, there is a method of performing organic substance removal and denitrification reaction of treated water by upflow anaerobic sludge bed method (UASB) using granular sludge.

  In addition, as a similar circulating nitrification denitrification system, for example, a method of treating nitrogen-containing organic wastewater in which a nitrification tank is provided on the downstream side of a methane fermentation tank and a part of treated water is returned to the methane fermentation tank as circulating water. Are known. However, such a treatment method suppresses the growth of methane bacteria, which are obligately anaerobic bacteria (absolute anaerobic bacteria) that can grow only in the absence of free oxygen, because the dissolved oxygen concentration in the nitrification liquid is high. There was a problem called.

  In addition, for example, a treatment method is also known in which part of the nitrification solution is returned from the nitrification tank on the downstream side of the methane fermentation tank of UASB to the acid generation (and denitrification) tank provided on the upstream side of the methane fermentation tank of UASB. ing. However, such treatment methods require an acid generation tank while eliminating the need for a reactor for denitrification, and require at least three treatment tanks in total, such as requiring a nitrification tank on the latter stage side of the UASB tank, There was a problem that equipment became large.

  For example, there is also known a method of using a UASB tank for removing organic substances on the front side, providing a denitrification tank and a nitrification tank on the rear side, and returning the nitrification solution from the post-settling tank to the denitrification tank. . However, such treatment methods also require at least three treatment tanks in total, such as requiring a denitrification tank and a nitrification tank separately from the UASB tank at the latter stage side of the UASB tank, resulting in an increase in equipment size. .

Unexamined-Japanese-Patent No. 2010-058021 JP, 2006-272252, A Japanese Patent Application Publication No. 2001-212593

  The problem to be solved by the present invention is to provide a nitrification denitrification apparatus capable of efficiently carrying out nitrification denitrification with a small number of treatment vessels while not suppressing the growth of methane bacteria.

The nitrification denitrification apparatus according to the embodiment is a nitrification denitrification apparatus for performing nitrification and denitrification of water to be treated, comprising a first treatment tank and a second treatment tank, wherein the first treatment tank is a lower part And an anaerobic carrier layer filled with an anaerobic carrier loaded with methane bacteria, which is formed on top of the first carrier inlet for receiving the treated water, and is formed above the anaerobic carrier layer and carries denitrifying bacteria. A denitrification carrier layer filled with the denitrified carrier, and a first-class outlet for flowing intermediate treated water formed above the denitrification carrier layer and passing through the anaerobic carrier layer and the denitrification carrier layer; The second treatment tank is provided with a nitrification carrier carrying nitrifying bacteria in the tank, and a second inlet formed in the lower part to allow the intermediate treated water to flow, the intermediate treated water and the nitrification Aeration means for circulating aeration of the carrier, and formed on the top to be in contact with the nitrification carrier It has a second outlet for discharging the physical water, wherein the return passage to return toward the first processing tank the part of the treated water as the circulating water is further formed, the said return flow path first The first supply port in one treatment tank is formed between the anaerobic carrier layer and the denitrifying carrier layer, and the second supply port of the return flow channel is formed in the lower part of the first treatment tank .

The schematic diagram which shows the nitrification denitrification apparatus which concerns on 1st embodiment. The schematic diagram which shows the nitrification denitrification apparatus which concerns on 2nd embodiment.

  Hereinafter, the nitrification denitrification apparatus of the embodiment will be described with reference to the drawings.

First Embodiment
FIG. 1 is a schematic view showing the configuration of a nitrification denitrification apparatus according to the first embodiment.
The nitrification denitrification apparatus 10 of this embodiment shown in FIG. 1 includes an anaerobic tank (first treatment tank) 11 and an aeration tank (second treatment tank) 12 in this order from the upstream side where raw water (water to be treated) W1 flows. And a treatment tank 13. Moreover, the circulation flow path 14 which connects the process water tank 13 and the anaerobic tank 11 is formed. In the middle of the circulation flow path 14, a pump 15 for feeding a part of the treated water W 3 stored in the treated water tank 13 to the anaerobic tank 11 is formed.

  The anaerobic tank (first treatment tank) 11 is a water tank capable of storing water therein, and has a first inlet 11a at the bottom and a first outlet 11b at the top, for example, near the liquid surface. Raw water (water to be treated) W1 to be treated in the anaerobic tank 11 flows in from the first-class inlet 11a. The anaerobic tank 11 is sealed to keep the inside of the tank in an anaerobic state. In addition, on the upstream side (pre-stage side) of the anaerobic tank 11, a water tank or the like for storing the raw water W1 may be further provided.

  Inside the anaerobic tank (first treatment tank) 11, an anaerobic carrier layer 21 formed in the lower part and a denitrifying carrier layer 22 disposed above the anaerobic carrier layer 21 are provided. Raw water W1 flowing into the anaerobic tank 11 from the first-class inlet 11a sequentially passes through the anaerobic carrier layer 21 and the denitrifying carrier layer 22 upward, and is discharged from the first-class outlet 11b as intermediate treated water W2.

  The anaerobic carrier layer 21 is composed of a large number of anaerobic carriers 23 carrying methane bacteria. The anaerobic carrier 23 is composed of, for example, a foam (supporting base material) of a mixture based on a substantially bullet-like to cylindrical polyolefin-based resin as a base material, and methane bacteria (methanogenic bacteria) supported on the foam. Methane bacteria are obligately anaerobic bacteria, generate methane gas from organic components contained in the raw water W1, and reduce the concentration of organic substances contained in the raw water W1.

  The foam (supporting base material) for supporting methane bacteria may be a porous resin or the like, and is preferably a hydrophilic resin or a water absorbing resin. The size of the foam (supporting base material) is about 1 to 10 mm in diameter, for example, about 4 mm.

The specific gravity of such an anaerobic carrier 23 is, for example, 1.10 to 1.20, preferably 1.16 to 1.17. In the present embodiment, the specific gravity of the anaerobic carrier 23 constituting the anaerobic carrier layer 21 is 1.16.
The ratio of the volume of the anaerobic carrier layer 21 to the volume of the entire anaerobic tank (first treatment tank) 11 is about 10% to 40%.

  The denitrifying carrier layer 22 is composed of a large number of denitrifying carriers 24 carrying denitrifying bacteria. The nitrogen removal carrier 24 has, for example, a cylindrical or cubic shape, and is a foam (supporting base material) of a synthetic resin containing polyethylene glycol as a main component, and a nitrogen removal bacteria (denitrification bacteria) loaded on the foam. It consists of The denitrifying bacteria are facultative anaerobic bacteria, and reduce nitrate ions contained in the raw water W1 having passed through the anaerobic carrier layer 12 to nitrogen to reduce the concentration of nitrate ions contained in the raw water W1.

  The foam (supporting base material) for supporting the denitrifying bacteria may be a porous resin or the like, and is preferably a hydrophilic resin or a water absorbing resin. The size of the foam (supporting base material) is about 1 to 10 mm in diameter, for example, about 4 mm.

As such a nitrogen removal carrier 24, one having a specific gravity smaller than that of the anaerobic carrier 23 is used. The specific gravity of the nitrogen removal carrier 24 is, for example, 1.01 to 1.2, preferably 1.01 to 1.2. In the present embodiment, the specific gravity of the denitrifying carrier 24 constituting the denitrifying carrier layer 22 is 1.05.
The ratio of the volume of the denitrifying carrier layer 22 to the volume of the entire anaerobic tank (first treatment tank) 11 is about 10% to 40%.

  Thus, by making the specific gravity of the anaerobic carrier 23 and the denitrifying carrier 24 different, the raw water W1 is introduced from the lowermost first inlet 11a of the anaerobic tank 11 and flows upward toward the upper first outlet 11b. However, the rising water flow does not cause the anaerobic carrier 23 and the denitrifying carrier 24 to be mixed. In particular, by using the denitrification carrier 24 having a specific gravity smaller than that of the anaerobic carrier 23, the anaerobic carrier 23 always sinks to the lower part of the denitrification carrier 24. Therefore, between the anaerobic carrier layer 21 and the denitrification carrier layer 22. Even if there is no partition etc. in particular, the position of each layer is maintained in order of the anaerobic carrier layer 21 and the denitrifying carrier layer 22 from the lower side in the anaerobic tank 11.

In addition, the rising flow rate of raw water W1 in the anaerobic tank (first treatment tank) 11 is 5 to 40 kg-BOD / m ³ · d, and the HRT (hydraulic retention time) is 2 to 10 for the volume load of organic substance in the anaerobic carrier layer. When it is time, it is determined based on the cross-sectional area determined from the aspect ratio of the dimensions in the tank of the anaerobic tank 11.

  Moreover, it is preferable that temperature control means (not shown) is further provided in the anaerobic tank (first treatment tank) 11. In order to maintain the methane bacteria carried by the anaerobic carrier 23 as a biofilm, it is preferable to keep the raw water W1 at 34 to 37 ° C., which is the optimum active water temperature of the methane bacteria. Therefore, especially when the water temperature of the raw water W1 is low, such as in winter, the activity of methane bacteria is enhanced by heating the inside of the anaerobic tank 11 by a temperature control means such as a heater, and the methane generation efficiency is optimized. Can.

  The first inlet 11a formed in the lower part of the anaerobic tank 11 is preferably constituted by a distribution pipe (not shown) or the like provided with a large number of openings in order to uniformly distribute in the cross section of the anaerobic tank 11. Thereby, the raw water W1 flows uniformly in the cross section of the anaerobic tank 11, and the raw water W1 can be treated with uniform processing efficiency in the cross sectional direction of the anaerobic tank 11.

  The aeration tank (second treatment tank) 12 is a water tank capable of storing water inside, and a second inlet 12a is formed at the lower part, and a second outlet 12b is formed at the upper part, for example, near the liquid surface. . Intermediate treated water W2 treated in the anaerobic tank 11 flows in from the second inlet 12a.

  The aeration tank (second treatment tank) 12 includes a large number of nitrifying carriers 25 carrying nitrifying bacteria in the tank. Further, in the aeration tank 12, an aeration means 26 for agitating and aerating the intermediate treated water W2 and the nitrification carrier 25 is formed. Examples of the aeration means 26 include a configuration such as an air blower device that blows air from the lower part of the aeration tank 12 to form a swirling flow in the aeration tank 12 of the intermediate treated water W2 and the nitrification carrier 25. The intermediate treated water W2 flowing into the aeration tank 12 from the second inlet 12a is sufficiently in contact with the nitrification carrier 25 in the tank by the aeration means 26, and is discharged as the treated water W3 from the second outlet 12.

  The nitrification carrier 25 is composed of, for example, a foam (supporting base material) of a mixture having a cylindrical or cubic polyolefin resin as a base material, and nitrifying bacteria supported on the foam. The nitrifying bacteria are aerobic bacteria, and generate nitrite and nitrate from ammonia contained in the intermediate treated water W2.

  The foam (supporting base material) for supporting the nitrifying bacteria may be a porous resin, cubic sponge or the like, and is preferably a hydrophilic resin or a water absorbing resin. In addition, the size of the foam (supporting base material) is about 1 to 10 mm in diameter, for example, about 4 mm in diameter if it is spherical, and about 10 mm in outside size if it is cubic.

  The specific gravity of such a nitrification carrier 25 is, for example, 0.95 to 1.1. The ratio of the total volume of the nitrification carrier 25 to the volume of the entire aeration tank 12 is about 10% to 40%.

  The treated water tank 13 is a water tank that can store water inside, and stores the treated water W3 that has flowed out from the second outlet 12 of the aeration tank 12.

Further, the circulation flow path 14 is constituted by a pipe or the like connecting the treated water tank 13 and the anaerobic tank 11, and a part of the treated water W3 of the treated water tank 13 is sent to the anaerobic tank 11 by the pump 15.
In the vicinity of the boundary between the anaerobic carrier layer 21 and the denitrifying carrier layer 22 of the anaerobic tank 11, a first supply port 28 for introducing the treated water W3 returned through the circulation channel 14 into the anaerobic tank 11 is formed. There is.

The operation of the nitrification denitrification apparatus 10 according to the first embodiment having the above-described configuration will be described.
When the raw water W1, which is the water to be treated containing an organic substance, is to be subjected to nitrification and denitrification using the nitrification denitrification apparatus 10 of the present embodiment, first, the raw water W1 is formed from the first inlet 11a formed in the lower part of the anaerobic tank 11. Is introduced into the anaerobic tank 11.

  Raw water W <b> 1 introduced into the anaerobic tank 11 first passes through the anaerobic carrier layer 21 formed in the lower part of the anaerobic tank 11. At this time, methane gas is generated from the organic matter component contained in the raw water W1 in contact with the methane bacteria (methanogenic bacteria) of the anaerobic carrier 23, and the organic substance concentration contained in the raw water W1 is reduced.

  Next, the raw water W 1 passes through the denitrifying carrier layer 22 formed on the anaerobic carrier layer 21 by the rising water flow in the anaerobic tank 11. At this time, the raw water W1 in contact with the denitrifying bacteria (denitrifying bacteria) of the denitrification carrier 24 and the nitrate ion contained in the treated water W3 returned via the circulation channel 14 are reduced to nitrogen, and the raw water W1 and the circulation channel The concentration of nitrate ion contained in the treated water W3 returned through 14 is reduced.

  Thus, the raw water W1 rising inside the anaerobic tank 11 passes the anaerobic carrier layer 21 and the denitrifying carrier layer 22 successively, but the specific gravity of the anaerobic carrier 23 and the denitrifying carrier 24 are made different. Thus, even if the raw water W1 forms a rising water flow, the rising water flow does not mix the anaerobic carrier 23 and the nitrogen removal carrier 24.

  As in the present embodiment, by using the denitrification carrier 24 having a specific gravity smaller than that of the anaerobic carrier 23, the anaerobic carrier 23 always sinks to the lower part of the denitrification carrier 24, so the anaerobic carrier layer 21 and the denitrification carrier Even if there is no partition between the layer 22 and the like, the position of each layer is maintained in the order of the anaerobic carrier layer 21 and the denitrifying carrier layer 22 from the lower side in the anaerobic tank 11. As a result, it becomes possible to coexist the methanogenesis step and the nitrification step without partitioning the inside of one water tank (anaerobic tank 11), and the nitrification capable of efficient nitrification and denitrification in a small number of treatment tanks. The denitrifying device 10 can be realized. For example, in the present embodiment, the nitrification and denitrification apparatus 10 can be configured by two water tanks.

  Thereafter, the intermediate treated water W2 whose organic substance concentration and nitrate ion concentration have been reduced by the anaerobic tank 11 is introduced into the aeration tank (second treatment tank) 12 from the second inflow port 12a. The intermediate treated water W2 introduced into the aeration tank 12 forms a swirling flow by the aeration means 26, for example, an air blower, etc., and sufficiently contacts the nitrification carrier 25. At this time, nitrous acid and nitric acid are generated from the ammonia contained in the intermediate treated water W2 in contact with the nitrifying bacteria of the nitrifying carrier 25.

Through the aeration tank 12, the treated water W 3 which has been subjected to the nitrification and denitrification is discharged from the second outlet 12 b and stored in the treated water tank 13.
Then, a portion of the treated water W3 stored in the treated water tank 13 is returned to the anaerobic tank 11 via the circulation channel 14 as circulating water (nitrification liquid) W4, and the anaerobic carrier layer 21 and the denitrifying carrier layer 22 Introduced during the Then, the returned treated water W3 passes through the denitrifying carrier layer 22 together with the raw water W1 by the upflow to reduce the remaining nitrate ions to nitrogen.

  The amount of water to be returned to the anaerobic tank 11 through the circulation channel 14 in the treated water W3 of the treated water tank 13 is appropriately determined in accordance with the water quality of the raw water W1, the nitrate ion concentration of the treated water W3, etc. It is preferable to use about 1 to 10 times the amount of water of W1.

Second Embodiment
FIG. 2 is a schematic view showing the configuration of the nitrification denitrification apparatus according to the second embodiment.
In the following description, the same components as those of the nitrification denitrification apparatus according to the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.
In the nitrification denitrification apparatus 30 of the present embodiment shown in FIG. 2, a part of the treated water W3 stored in the treated water tank 13 is returned to the anaerobic tank (first treatment tank) 11 as the circulating water W4. The feed port on the side of the anaerobic tank 11 is added to the first feed port 28 between the anaerobic carrier layer 21 and the denitrifying carrier layer 22, and the feed side of the raw water W1 flowing into the lower portion of the anaerobic tank 11 is also A second supply port 29 is formed.

  The first measuring means 31 for measuring the organic substance concentration on the inflow side of the anaerobic tank (first treatment tank) 11 and the second measuring means 32 for measuring the organic substance concentration of the treated water W3 stored in the treated water tank 13 Have. As the first measurement means 31 and the second measurement means 32, for example, a continuous measurement BOD measurement device or a COD measurement device can be used.

  Further, a diversion controller 33 is formed on the way of the circulation channel 14. An organic substance concentration signal output from the first measurement unit 31 or the second measurement unit 32 is input to the diversion controller 33. Then, the flow dividing controller 33 controls the flow rates of the circulating water W4 to be divided into the first supply port 28 and the second supply port 29 based on the measurement results of the organic substance concentration of the raw water W1 and the treated water W3. .

  According to the nitrification denitrification apparatus 30 according to the second embodiment, the ratio of the circulating water W4 for starting the treatment from the denitrification carrier layer 22 and the ratio of the circulating water W4 for starting the treatment from the anaerobic carrier layer 21 It becomes possible to control optimally according to the measurement result of the organic substance concentration of W1 and the treated water W3.

  For example, when the organic matter concentration of the raw water W1 is low, the proportion of circulating water W4 diverted to the second supply port 29 is reduced, and the anaerobic carrier layer 21 containing absolutely anaerobic methane bacteria is circulated water (nitrification liquid) W4 The anaerobic atmosphere can be maintained without causing the aerobic atmosphere by the high dissolved oxygen contained in the By this, it can be prevented that the growth of methane bacteria, which are obligately anaerobic bacteria that can grow only in the absence of free oxygen, can be suppressed, and the water treatment capacity of the anaerobic carrier layer 21 can be kept high. .

  In addition, when the organic matter concentration of the raw water W1 is high, the organic matter concentration of the raw water W1 is reduced by increasing the proportion of the circulating water W4 which is diverted to the second supply port 29, and an anaerobic carrier layer containing absolute anaerobic methane bacteria. 21 can be properly maintained.

  In addition, when the organic matter concentration of the treated water W3 is high, the proportion of the circulating water W4 diverted to the second supply port 29 is increased, and the circulating water (nitrification liquid is used in the anaerobic carrier layer 21 containing absolutely anaerobic methane bacteria. ) W4 can be reprocessed.

  The flow division controller 33 may be configured to reference only the organic substance concentration signal from the first measurement unit 31. That is, without forming the second measurement means 32, referring to only the organic matter concentration of the raw water W1, the flow rates at the time of dividing the circulating water W4 into the first supply port 28 and the second supply port 29 are controlled. It may be a configuration.

  According to at least one embodiment described above, by making the specific gravity of the denitrification carrier different from the specific gravity of the anaerobic carrier, the anaerobic carrier layer and the denitrification carrier layer do not need to be partitioned particularly. In the tank, the positions of the anaerobic carrier layer and the denitrifying carrier layer are maintained. This makes it possible to coexist the methanogenesis step and the nitrification step without partitioning the inside of one tank, and realizes a nitrification denitrification apparatus capable of efficiently performing nitrification denitrification with a small number of treatment tanks. it can.

  While certain embodiments of the present invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and the equivalents thereof as well as included in the scope and the gist of the invention.

  10: nitrification denitrification apparatus, 11: anaerobic tank (first treatment tank), 12: aeration tank (second treatment tank), 14: circulation channel, 21: anaerobic carrier layer, 22: denitrification carrier layer, 23: ... Anaerobic carrier, 24: denitrification carrier, 25: nitrification carrier.

Claims (5)

Nitrification and denitrification equipment to carry out nitrification and denitrification of treated water,
Having a first treatment tank and a second treatment tank,
The first treatment tank has a first-class inlet formed in the lower portion to allow the treated water to flow in, an anaerobic carrier layer filled with an anaerobic carrier loaded with methane bacteria, and an upper portion above the anaerobic carrier layer A denitrification carrier layer formed and loaded with a denitrification carrier supporting denitrifying bacteria, and an intermediate treatment formed on the denitrification carrier layer and passing through the anaerobic carrier layer and the denitrification carrier layer Have a first-class outlet to drain water,
The second treatment tank is provided with a nitrification carrier carrying nitrifying bacteria in the tank, and a second inlet formed in the lower part to allow the intermediate treated water to flow in, and aerating the intermediate treated water and the nitrification carrier in circulation And a second outlet for draining the treated water formed on the upper portion and in contact with the nitrification carrier ,
There is further formed a return flow path for returning a portion of the treated water as circulating water toward the first treatment tank, and the first supply port in the first treatment tank of the return flow path is an anaerobic carrier layer and denitrification A nitrification and denitrification apparatus characterized in that it is formed between the carrier layer and a second supply port of the return flow channel in the lower part of the first treatment tank .     The specific gravity of the said anaerobic support | carrier and the said denitrification support | carrier was varied, The nitrification denitrification apparatus of Claim 1 characterized by the above-mentioned.     3. The nitrification and denitrification apparatus according to claim 2, wherein the denitrification carrier has a smaller specific gravity than the anaerobic carrier. The flow rate of the circulating water to be flowed to the first supply port and the circulation to be flowed to the second supply port based on the first measurement means for measuring the organic matter concentration of the water to be treated and the measurement result by the first measurement means 2. The nitrification and denitrification apparatus according to claim 1 , further comprising a diversion controller for controlling the flow rate of water. The apparatus further comprises second measuring means for measuring the organic matter concentration of the treated water, and the diversion controller further refers to the measurement result by the second measuring means in addition to the measurement result by the first measuring means. The nitrification denitrification apparatus according to claim 4 , wherein

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