JP5023379B2 - Purification method and equipment for treated water - Google Patents

Description

  The present invention relates to a water purification treatment method, and further relates to purification equipment for performing the treatment method.

  In order to prevent pollution of rivers and oceans, it is important to treat urban wastewater. In particular, TN (total nitrogen) reduction in wastewater is becoming more important due to stricter emission regulations.

TN in the wastewater includes ammonia nitrogen (hereinafter referred to as N-NH ₄ ), nitrate nitrogen and nitrite nitrogen (hereinafter referred to as N-NO _{2 + 3} ), and organic nitrogen (hereinafter referred to as Org-N). . Among these, purification methods for reducing N-NO _{2 + 3} include, in industrial chemistry, a membrane separation method, an ion exchange method, a boiling / evaporation method, and a method using denitrifying cells. Among these, methods using denitrifying bacteria are widely used as N-NH ₄ , N-NO _{2 + 3} , and Org-N, and their costs are relatively low, and they are widely used.

The denitrifying bacterium refers to a group of microorganisms such as soil microorganisms that generate N ₂ gas from N—NO _{2 + 3} in waste water. Further, in the denitrification treatment using denitrifying cells, N-NO ₂ is used when the denitrifying cells are in a low oxygen state (hereinafter referred to as anaerobic state. Conversely, a high oxygen state is referred to as an aerobic state). It uses the consumption of oxygen in ₊₃ .

  As purification facilities for drainage and the like using denitrifying bacteria, water-channel and biotope facilities used for purification of lakes and the like are known for outdoor and wide-area types. Moreover, industrially, as shown in Patent Document 1, a method using a plant is known. Furthermore, as shown in Patent Document 2, the miniaturization of equipment by simultaneous processing is also being studied.

JP 50-147154 A JP 2005-34739 A

  However, the water channel type and biotope type facilities are not very efficient, and a large area and time are required to perform sufficient denitrification. Moreover, although the method of patent document 1, 2 is easy to manage compared with facilities, such as a water channel type, and processing efficiency is excellent, it is inferior in terms of initial cost and running cost. In particular, the method of Patent Document 1 often has a large facility. Further, the method of Patent Document 2 tends to be higher in cost.

  An object of the present invention is to improve denitrification efficiency in a water channel type purification equipment having a relatively simple structure and low operating cost.

According to the present invention, there is provided a method for purifying by flowing water to be treated containing nitrate nitrogen or nitrite nitrogen in a water channel in which anaerobic denitrifying bacteria are propagated, the water to be treated flowing into the water channel The bottom surface of a non-breathable container is brought into contact with the water surface, the container is floated so as to cover the entire surface of the water channel, soil or plant material is accommodated in the container, and further planted in the container The purification method of the to-be-processed water characterized by the above-mentioned is provided.

Moreover, according to the present invention, it is a facility for purifying by flowing water to be treated containing nitrate nitrogen or nitrite nitrogen into a water channel in which anaerobic denitrifying bacteria are propagated, and the water to be treated flowing into the water channel The bottom surface of a non-breathable container is in contact with the water surface of the water , the container floats so as to cover the entire surface of the water channel, soil or plant material is accommodated in the container, and is further planted in the container characterized in that there, cleaning equipment of the water to be treated is provided.

  Furthermore, you may install the resistance object which diverts the flow of to-be-processed water so that to-be-processed water and a microbial cell may contact easily in the said water channel. In this case, the resistive object is, for example, a tree branch or root.

  According to the present invention, the surface of the water to be treated is covered with a substantially non-breathable coating member, thereby preventing the oxygen from being dissolved into the water to be treated from the water surface, and also the growth of green algae in the water to be treated Can be suppressed. Thereby, it maintains in an anaerobic state in a water channel, and the denitrification effect by an anaerobic denitrification microbial cell improves. In the case of the biotope and water channel type, the temperature is expected to decrease in winter and the processing efficiency is expected to deteriorate, but by covering with a covering member, heat radiation to the atmosphere in winter can be prevented. If a black sheet is used, effective use of solar heat is also possible. In addition, if planted in a container that covers the water surface, nitrate nitrogen is absorbed during plant growth, and further the ability to reduce nitrate nitrogen is improved, the appearance is improved, and it can be a legal environmental facility. . In addition, if a resistance object that bypasses the flow of treated water is installed in the water channel, the contact frequency between the bacteria and treated water increases, and denitrifying bacteria adhere to and accumulate around the resistant object. The contact area of the denitrifying cells is also increased, and the denitrification efficiency is further improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of a purification facility 1 according to an embodiment of the present invention, FIG. 2 is a plan view of the purification facility 1 according to an embodiment of the present invention, and FIG. 3 is another embodiment of the present invention. FIG. 4 is an explanatory view of the purification facility 1 according to the present invention, FIG. 4 is an explanatory view of the purification facility 1 according to still another embodiment of the present invention, and FIG. 5 is an explanatory view of a conventional purification facility 1 ′. Note that in the present specification and the accompanying drawings, components having the same configuration and function are denoted by the same reference numerals, and redundant description is omitted.

As shown in FIGS. 1 and 2, denitrifying bacteria 11 such as soil microorganisms are propagated and deposited at the bottom of the water channel 10. The treated water 15 containing N-NO _{2 + 3} passes over the denitrifying microbial cells 11, and the treated water 15 is purified while flowing through the water channel 10. In the illustrated example, the water to be treated 15 flows from right to left in FIGS.

  Thus, when purifying with denitrifying bacteria 11 while flowing the water 15 to be treated into the water channel 10, it is necessary to maintain an anaerobic state. However, it is difficult to maintain, leading to a decrease in processing efficiency. In the case of the conventional purification equipment 1 ′, as shown in FIG. 5, the aerobic cells 12 are present on the surface layer side and the anaerobic cells 13 are present on the bottom side of the water channel 10. . For this reason, the treatment efficiency on the surface layer side that is always in contact with the water to be treated 15 is high, but the anaerobic microbial cells 13 deposited therebelow have poor contact efficiency with the water to be treated 15 and denitrification efficiency. Lower.

  Therefore, in the present invention, as shown in FIGS. 1 and 2, the water surface of the water to be treated 15 is covered with a covering member 16 having a lighter specific gravity than water and substantially no air permeability and light permeability. The covering member 16 may have some air permeability and may be any member that can maintain the inside of the water channel 10 in an anaerobic state. The material of the covering member 16 may be vinyl, wood, foamed polystyrene, polyvinyl chloride or the like. Although it is necessary to consider the environment, a method of covering the surface of the water to be treated 15 with oil or the like is also conceivable. The covering member 16 may be fixed according to the height of the water surface. However, if the water surface height of the water 15 to be treated fluctuates, if the one that floats on the water surface is selected, it moves up and down according to the water surface. So convenient.

  Further, if the covering member 16 having a heat insulating effect is selected, a heat retaining effect can be obtained even in a situation where the air temperature is lower than the water temperature in winter, which is advantageous for processing. In this case, for example, if a black sheet is used as the covering member 16, solar heat can be used advantageously.

  Thus, by covering the water surface of the water to be treated 15 with the coating member 16 having no air permeability and light permeability, the inside of the water channel 10 is maintained in an anaerobic state, and the heat retaining effect, the water to be treated 15 and the denitrifying microbial cells are maintained. The contact efficiency with 11 is also improved, and the processing efficiency is improved. Moreover, since the water surface is shielded, there is also an effect of preventing scum (floating) due to floating / drying of the denitrifying bacteria 11.

  In addition, as for the residence time in the water channel 10, it is desirable to be able to ensure the time according to processing capacity. Further, regarding the depth of the water channel 10, there is no problem when stirring or the like is performed, but in the case of only water flow conditions, the contact efficiency between the denitrifying microbial cells 11 and the water to be treated 15 is considered to be about 50 cm or less. desirable. If possible, it can be 30 cm or less. In addition, a weir is provided at the outlet of the water channel 10 to prevent excessive denitrification bacteria 11 from being discharged, and the treated water 15 is discharged by overflow.

  Although an example of a preferred embodiment of the present invention has been described based on FIGS. 1 and 2, the present invention is not limited to the form shown in FIGS. It will be apparent to those skilled in the art that various changes or modifications can be made within the scope of the ideas described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, in order to improve the contact efficiency between the denitrifying microbial cells 11 and the water to be treated 15, as shown in FIG. 3, a resistance object having a large contact area such as a pruned tree branch 19 is immersed in the water channel 10. Alternatively, a resistance object such as a planting root 20 is disposed in the water channel 10. Thus, by detouring the flow of the water to be treated 15 with the resistance object, the water to be treated 15 comes into contact with a higher probability than the denitrifying fungus body 11, and the treatment efficiency is improved. Moreover, although the operation cost is high, stirring is also effective.

  As a method for increasing the contact area between the water to be treated 15 and the denitrifying microbial cells 11, it is also effective to replenish a filler having a high porosity, but this increases the cost, so waste branches and waste materials The use of is sufficient. It is also effective to plant floats on water and use the planted roots (Fig. 3). However, the treatment efficiency is higher when there are more resistance objects, but if it becomes excessive, the water flow will be hindered and flooding will occur.

  FIG. 4 shows still another embodiment according to the present invention, in which a cocoon-shaped container 21 is laid so as to cover the entire surface of the water channel 10, and plant-based materials made of soil, straw, coarse cocoon, etc. are placed in the container 21. It is housed and further planted in the container 21. The container 21 is bowl-shaped and has air permeability and water permeability. However, by containing soil or plant material in the container 21, the container 21 becomes substantially non-air-permeable. The type of soil and plant-based materials is arbitrary and can be planted inside them. The kind of plant 22 to be planted is not limited. By accommodating soil or plant material in the container 21, any plant other than hydroponic plants can be planted, and the aesthetics can be improved depending on the type of the plant 22.

  The container 21 may be supported and fixed by a frame, a stand or the like (not shown), or may be attached by hooking the upper end of the container 21 to a water channel. Further, a float may be attached to the container 21 to float on the water surface. In either method, the container 21 is disposed so as to cover the entire surface of the water channel 10 so that the bottom surface of the container 21 always contacts the water surface and the water surface does not contact the atmosphere. Further, as in the example of FIG. 3, the tree branch 19 is placed in the water channel 10 as a resistance object.

  In the above example, the water channel 10 may be covered with a container 21 that contains only soil or plant-based material without planting the plant 22. Further, the container 21 floating on the water channel 10 is not limited to a container having air permeability and water permeability such as a basket, and may be a container made of a material having no air permeability.

Water was flowed at a flow rate of 1 m ³ / h in a water channel with a water storage capacity of 5 m ³ (width 2.5 m, length 10 m). As for the setting in the water channel, underwater, a planted paddle filled with rough straw was immersed in almost the entire water channel, and the water surface was covered with a blue sheet made of 1 mm thick vinyl so that it did not come into contact with air. As for the inlet water quality, the TOC concentration was 38.2 mg / L, pH 7.56, and the water temperature was 18 ° C. As a result of the water flow, the outlet TN concentration was 27.5 mg / L (reduced 33 mg / L) while the inlet TN concentration was 60.5 mg / L. In addition, TN was measured using a TOC-V meter manufactured by Shimadzu Corporation, which employed a catalytic pyrolysis-chemiluminescence method (Kemirmumi method). The processing efficiency was 316.8 g / m ³ / d.

In a water channel with a water storage capacity of 5m ³ (width 2.5m, length 10m), a weir was installed on the outlet side and closed. 5m ³ of raw water was introduced, and treated water on the outlet side was delivered to the inlet side at a flow rate of 5m ³ / h for circulation treatment. The setting in the water channel was the same as in Example 1. As for the inlet water quality, the TOC concentration was 50.7 mg / L, pH 7.15, and the water temperature was 20 ° C. After 5 hours, the outlet TN concentration was 61.5 mg / L (decreased 60.3 mg / L) against the inlet TN concentration of 121.8 mg / L. The processing efficiency was 289 g / m ³ / d.

Water was flowed at a flow rate of 5 m ³ / h in a channel with a water storage capacity of 5 m ³ (width 2.5 m, length 10 m). As the setting in the water channel, a mesh-like planting basket filled with coarse straw was immersed in the entire surface of the water channel. Furthermore, the planting basket which planted the watercress by putting a basket on it was arrange | positioned so that a bottom face might contact the water surface, and the whole waterway was coat | covered with the planting basket. As for the inlet water quality, the TOC concentration was 24.4 mg / L, the pH was 6.98, and the water temperature was 21.4 ° C. As a result of water flow, the outlet TN concentration was 20.1 mg / L (decreased 13.6 mg / L) while the inlet TN concentration was 33.6 mg / L. The processing efficiency was 339 g / m ³ / d.

(Comparative Example 1)
From the example of Patent Document 2, as a result of carrying out with a hollow fiber module surface area of 0.25 m ² , equipment capacity 5 L, inflow ² L / d, 0.01 MPa, a reduction effect of about 0.23 mg / m ² / d of TN was obtained. In terms of treatment efficiency, it was 15.3 g / m ³ / d.

(Comparative Example 2)
Water was flowed at a flow rate of 1 m ³ / h in a water channel with a water storage capacity of 5 m ³ (width 2.5 m, length 10 m). As a water channel setting, a planting basket filled with coarse koji was immersed in almost the entire water channel, and the water surface was left in contact with the atmosphere. As for the inlet water quality, the TOC concentration was 37.9 mg / L, pH 7.22, and the water temperature was 18 ° C. After 0.5 h, the outlet TN concentration was 80.1 mg / L (down 1.1 mg / L) against the inlet TN concentration of 83.2 mg / L. The processing efficiency was 10.6 g / m ³ / d.

  The present invention can be applied to water purification.

It is explanatory drawing of the purification equipment concerning embodiment of this invention. It is a top view of purification equipment concerning an embodiment of the invention. It is explanatory drawing of the purification equipment concerning other embodiment of this invention. It is explanatory drawing of the purification equipment concerning further another embodiment of this invention. It is explanatory drawing of the conventional purification equipment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Purification equipment 10 Water channel 11 Denitrifying microbial cell 15 Water to be treated 16 Covering member 19 Tree branch 20 Planting root 21 Container

Claims (6)

A method of purifying by flowing water to be treated containing nitrate nitrogen or nitrite nitrogen into a waterway where anaerobic denitrifying bacteria have been propagated,
The bottom surface of a non-breathable container is brought into contact with the surface of the water to be treated flowing into the water channel, the container is floated so as to cover the entire surface of the water channel, and soil or plant material is contained in the container, Furthermore, planting in the said container, The purification method of the to-be-processed water characterized by the above-mentioned . The method for purifying treated water according to claim 1, wherein a resistance object that bypasses the flow of treated water is installed in the water channel . The method for purifying treated water according to claim 2, wherein the resistance object is a tree branch or root . A facility for purifying by flowing water to be treated containing nitrate nitrogen or nitrite nitrogen into a waterway where anaerobic denitrifying bacteria were propagated,
  The bottom surface of a non-breathable container is in contact with the water surface of the water to be treated flowing into the water channel, the container floats so as to cover the entire surface of the water channel, soil or plant material is contained in the container, and A purification facility for water to be treated, which is planted in a container. The purification apparatus of the to-be-processed water of Claim 4 characterized by the above-mentioned. The resistance object which diverts the flow of to-be-processed water is installed in the said water channel. 6. The treatment water purification equipment according to claim 5, wherein the resistance object is a tree branch or root.

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