Biological treatment tank with carrier filter

Abstract

To prevent a surface area and a volume of a carrier filter 2 from decreasing so that a wastewater treatment facility 10 can function stably for a long period of time.SOLUTION: A biological treatment tank with a carrier filter is configured such that in a biological treatment tank 1, a carrier filter 2 is charged and filled, and a perforated screen 6 is provided to prevent the carrier filter 2 from flowing out. A wall surface 1a of the biological treatment tank 1 is filled with putty to fill in any uneven surface areas, and then a base treatment 24 is performed. An FRP layer 26 and a base polyester resin containing a hardener are applied to the surface of the base treatment 24. Then, a glass mat 25 is attached to the surface of the FRP layer 26. The surface of the glass mat 25 is again coated with the FRP layer 26 and a base polyester resin containing a hardener, and a lamination process is repeated. Finally, a surface finishing resin 27 is applied to perform a final smoothing process on a surface layer 27a.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a biological treatment tank having a carrier filter medium for decomposing and removing pollutants in a wastewater treatment process. [Background technology]

[0002] Conventionally, as shown in FIG. 10, carrier filter medium 2 is poured into a biological treatment tank 40 made of concrete (10% to 40% of the tank volume), and the carrier filter medium 2 is mixed with air by air diffusers 42, 42'. With the carrier filter medium 2 circulating inside the wall surface 40a of the biological treatment tank 40, wastewater passes through the tank inlet (flowing in from the previous tank) of the biological treatment tank 40 via advection, whereby pollutant components are decomposed and sent to the next tank.

[0003] The carrier filter material 2 is mainly a resin sponge-like cubic shape with a side length of A = 10 mm to 20 mm (see Figure 11 (a)), and a mesh-like or punched porous screen 41 is often provided on the outlet side of the biological treatment tank 40 to prevent the carrier filter material 2 from flowing out (see Figure 10). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-118692 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the carrier filter medium 2 is constantly circulating with the floating air in the biological treatment tank 40 due to air agitation, so it frequently collides and comes into contact with the inside of the wall surface 40a of the concrete layer. Since the wall surface 40a of the concrete layer is hard and has a rough surface, the soft carrier filter medium 2 is chipped away from the corners with each collision, and after 5 to 14 years of operation of the treatment facility, it is worn down to a small sphere with a diameter D of about 5 mm to about 8 mm or less (see Figures 11(b) to 11(d)).

[0006] If the biological treatment tank 40 facility continues to operate in this state, the particle size of the carrier filter medium 2 will become smaller than the holes (diameter = about 5 mm to 10 mm) of the porous plate screen 41 (after 10 years, diameter C = about 9 mm to 10 mm, after 14 years, diameter D = about 5 mm to 8 mm, see Figures 11(c) and (d)), and the carrier filter medium 2 will be transferred from the outlet of the biological treatment tank 40 to the next tank (see Figure 10). As a result, the carrier filter medium 2 will flow out into the discharge destination (rivers, sewage treatment plants, etc.).

[0007] Furthermore, clogging of the carrier filter medium 2 at the perforated plate screen 41 is likely to occur, and the wastewater may not be transferred and may overflow from the biological treatment tank 40 or flow into an adjacent tank.

[0008] In addition, the total area of ​​the biofilm layer, which is represented by the surface area of ​​the entire amount of the carrier medium 2, is also significantly reduced by the reduction in the volume of the carrier medium 2, and the total amount of microorganisms present on the surface of the carrier medium 2 and in the volume of the carrier medium 2. As a result, the organic matter decomposition reaction process that is removed by contact with the microbial film also becomes insufficient, and the removal of BOD (Biochemical Oxygen Demand) and COD (Chemical Oxygen Demand), which is the main purpose of the microbial treatment, cannot be fully achieved.

[0009] In either case, the performance of the wastewater treatment facility itself will be reduced, and significant losses will be incurred, including the need to recover the effluent (the carrier filter medium 2) and complaints from the recipients of the effluent.

[0010] The carrier filter medium 2 has a function of containing microorganisms therein and enhancing the capacity of purifying wastewater, and a reduction in the volume of the carrier filter medium 2 due to friction also results in a significant reduction in the treatment capacity.

[0011] In Patent Document 1, the inner walls of the denitrification tank and nitrification tank, which are made of concrete, have a hard, rough surface, so that the corners are scraped away by the carrier filter material with each collision, and the soft carrier filter material is scraped away from the corners with each collision, so that after 5 to 14 years of use, the treatment facility wears down to small spheres with a diameter of approximately 5 mm to approximately 8 mm or less.

[0012] Therefore, the present invention is made with the objective of solving the above problems and preventing the reduction in the surface area and volume of the carrier filter medium so that the wastewater treatment facility can function stably for a long period of time. [Means for solving the problem]

[0013] In order to achieve the above object, the present invention provides First, in the biological treatment tank (1), the carrier filter medium (2) circulating in the water by air agitation collides into and comes into contact with the wall surface (1a) of the concrete layer (1b), causing the carrier filter medium (2) to wear down. In relation to the reduction in volume and surface area of ​​the carrier filter medium (2) caused by the difference in roughness, hardness, and abrasiveness between the carrier filter medium (2) and the wall surface (1a) of the concrete layer (1b), an FRP layer (26) is coated on the wall surface (1a), making the wall surface (1a) soft and smooth, significantly reducing damage even if the carrier filter medium (2) collides into and comes into contact with the wall surface (1a). This allows the biological treatment tank to be configured with a carrier filter medium that maintains and retains the original performance of the biological treatment tank (1).

[0014] Secondly, the FRP layer (26) used in the biological treatment tank (1) has a stronger adhesion to the surface of the wall (1a) of the concrete layer (1b) than other coating waterproofing materials, and is resistant to the impact of the swirling water flow within the biological treatment tank (1). Therefore, the FRP layer (26) retains its properties for a long period of time without peeling off, thereby enabling a biological treatment tank of a first carrier filter material to retain and maintain the performance of the biological treatment tank (1). Effect of the Invention

[0015] As described above, in the present invention, the biological treatment tank 1 having the function of the carrier filter medium 2 significantly slows down the degree of wear and tear after the start of operation compared to the conventional technology. Therefore, it takes 20 to 30 years for the small spherical shapes to form (roughly the same number of years as the wastewater treatment facility 10 requires renewal and repair after the start of operation), and it is expected that the deterioration of the performance of the biological treatment tank 1 during that time will be suppressed and troubles will be prevented (troubles = recovery of the carrier filter medium 2 that has flowed out, complaints from the recipient of the flow, etc.), making it possible to maintain stable treatment performance for a long period of time.

[0016] Furthermore, compared to other coating waterproofing materials, the FRP layer 26 has a stronger adhesion to the concrete surface when it deteriorates over time, and will not peel off from the wall surface 1a, so its properties are maintained for many years. Even when repairs are required to repair deterioration, this can be done by applying a topcoat layer on the surface of the existing FRP layer 26, and large-scale repair work is rarely required. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic flow diagram of a wastewater treatment facility including a biological treatment tank for a filter medium according to the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of the two-ply state including the FRP layer including the biological treatment tank. [Diagram 3] FIG. 2 is a perspective view of a two-ply state including an FRP layer. [Figure 4] FIG. 3 is a cross-sectional view of the same in one ply including the biological treatment tank (cross-sectional view taken along line XX in FIG. 2). [Diagram 5] 2(a) to (e) are cross-sectional views (cross-sectional views taken along line XX in FIG. 2) of the two-ply system including the biological treatment tank. [Figure 6] 2(f) to (i) are cross-sectional views (cross-sectional views taken along line XX in FIG. 2) of the two-ply structure including the biological treatment tank. [Figure 7] FIG. 2 is a perspective view of the glass mat including the biological treatment tank. [Figure 8]1A is an enlarged view of the carrier outflow prevention screen including the biological treatment tank, FIG. 1B is an oblique view of the aeration device including the biological treatment tank (triangular cross section), and FIG. 1C is an oblique view of the aeration device including the biological treatment tank (circular cross section). [Figure 9] FIG. 2 is a correlation diagram between time of day and flow rate of a wastewater treatment facility including the biological treatment tank. [Figure 10] FIG. 1 is a cross-sectional view including a biological treatment tank of a conventional carrier filter medium. [Figure 11] (a) is before using the carrier filter media, (b) is after 5 years of using the carrier filter media, (c) is after 10 years of using the carrier filter media, and (d) is after 14 years of using the carrier filter media. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The biological treatment tank for the carrier filter medium according to the present invention will now be described.

[0019] FIG. 1 is an example of a schematic flow diagram of a wastewater treatment facility 10 including a biological treatment tank 1.

[0020] The raw water pump tank 11 is the tank into which wastewater from building facilities first flows, and a raw water pump 12 is installed to send water as needed to the flow rate adjustment tank 13. The flow rate adjustment tank 13 temporarily stores the wastewater sent from the raw water pump tank 11, and pressure-feeds a uniform amount of water to the biological treatment tank 1 using an adjustment pump 14 throughout the day (see Figure 9).

[0021] The biological treatment tank 1 purifies the wastewater sent from the upstream tank 13 mainly by the decomposition action of microorganisms. In many cases, aerobic microorganisms are used, and the carrier filter medium 2 is charged and filled into the biological treatment tank 1 (the carrier filter medium 2 accounts for 10% to 40% of the tank volume), and air is sent into the biological treatment tank 1 through the air diffusers 4, 4' (air outlets) by the aeration blower 3 (see Figures 8(b) and (c)), activating the sludge circulating in the biological treatment tank 1 and the microorganisms living in the carrier filter medium 2.

[0022] In the wastewater transferred from the biological treatment tank 1, the sludge settles to the bottom in the settling tank 5 and is separated from the supernatant water, which is transferred to the discharge pump tank 18. The settled sludge is pumped up by an air lift pump 19 and returned to the inlet of the biological treatment tank 1 via a sludge measuring tank 20 (returned sludge), and is repeatedly used for microbial purification of the carrier filter medium 2. The discharge pump tank 18 receives the supernatant water from the settling tank 5, and discharges it from the discharge pump 21 to the outside of the sewer system, etc. (sewer discharge, see Figure 1).

[0023] By continuing to operate the biological treatment function, the total amount of sludge in the wastewater treatment facility 10 will increase. To reduce the amount of sludge in the biological treatment tank 1, it is removed as excess sludge and temporarily stored in the sludge storage tank 22. Finally, the excess sludge is removed and disposed of outside the facility by a vacuum truck (sludge removal, see Figure 1).

[0024] Next, the biological treatment tank 1 will be described (see Figs. 2 and 3).

[0025] In order to achieve the above-mentioned object, in the present invention, an FRP layer 26 is coated on the wall surface 1a of the concrete layer 1b of the biological treatment tank 1, thereby making the tank surface of the biological treatment tank 1 soft and smooth, and thus significantly reducing wear and tear even when it comes into contact with the wall surface 1a of the carrier filter medium 2 (see Figures 2 and 3).

[0026] (Embodiment 1) In the present invention, the inner wall surface (wall surface 1a) of the concrete layer 1b of the biological treatment tank 1 is coated with an FRP (Fiber Reinforced Plastics) layer (glass fiber reinforced plastic, no adhesiveness) and a polyester resin base containing a hardener (adhesiveness) (hereinafter, the FRP layer and the polyester resin base containing a hardener are referred to as the "FRP layer 26"; see FIG. 4), making the wall surface 1a of the biological treatment tank 1 soft and smooth, so that even if the carrier filter medium 2 collides and comes into contact with it, wear damage is significantly reduced. This is because the glass mat 25 is adhered by coating with the polyester resin base containing a hardener (adhesiveness).

[0027] The biological treatment tank 1 has a rectangular parallelepiped or cubic shape (see Figs. 2 and 3), and when viewed microscopically, there are irregularities (1c, 1d) and holes (concave 1c) on the surface. The wall surface 1a of the concrete layer 1b has surface irregularities (1c, 1d) (see Fig. 4). The burrs (convex part 1d) are removed by cleaning with a scraper, and the recesses (concave 1c) are filled with resin, a hardener, and talc (a powdered silicate mineral = magnesium silicate hydrate (Mg 3 S 4 O 10 (OH) 2 )) is mixed and then filled with putty and then with a trowel or other tool (see Figure 4).

[0028] When the surface of the concrete layer 1b becomes smooth, the FRP layer 26 and the base polyester resin containing a hardener are laminated onto the wall surface 1a of the concrete layer 1b. In the present invention, since the FRP layer 26 has no adhesiveness, the FRP layer 26 and the base polyester resin containing a hardener (which has adhesiveness) are applied and coated to give it thickness (surface 26a, see Figure 4).

[0029] The glass mat 25 is cut to a size suitable for application, and the FRP layer 26 and the polyester resin containing a hardener are sufficiently applied to it with a roller or the like, and then the glass mat 25 is attached to the surface 26a. The FRP layer 26 and the polyester resin containing a hardener are further applied from above the glass mat 25 with a roller or the like until the glass mat 25 is soaked in the FRP layer 26 and the polyester resin containing a hardener (surface 26b, see Figure 4) (one ply completed).

[0030] The glass mat 25 is a mat-like material made of glass fibers (see FIG. 7).

[0031] (Embodiment 2) Figs. 5(a) to (e), Fig. 6(f) to (i) In the present invention, the inner wall surface (wall surface 1a) of the concrete layer 1b of the biological treatment tank 1 is coated with an FRP (Fiber Reinforced Plastics) layer (glass fiber reinforced plastic, no adhesiveness) and a polyester resin base containing a hardener (adhesiveness) (hereinafter, the FRP layer and the polyester resin base containing a hardener are referred to as the "FRP layer 26", see Fig. 5(a) to Fig. 6(i)). This makes the wall surface 1a of the biological treatment tank 1 soft and smooth, and even if the carrier filter medium 2 collides and comes into contact with the wall surface 1a, abrasion damage is significantly reduced. This is because the glass mat 25 is adhered by coating the polyester resin base containing a hardener (adhesiveness).

[0032] The biological treatment tank 1 has a rectangular parallelepiped or cubic shape (see Figs. 2 and 3), and when viewed microscopically, there are irregularities (1c, 1d) and holes (concave 1c) on the surface. The wall surface 1a of the concrete layer 1b has surface irregularities (1c, 1d) (see Fig. 5(a)). The burrs (convex part 1d) are removed by cleaning with a scraper, and the recesses (concave 1c) are filled with resin, a hardener, and talc (a powdered silicate mineral = magnesium silicate hydrate (Mg 3 S 4 O 10 (OH) 2)) is mixed and applied as putty, then filled in with a trowel or similar tool (see Figure 5(a)).

[0033] In order to laminate the FRP layer 26 and the main polyester resin containing a hardener on the wall surface 1a of the concrete layer 1b, a base treatment 24 (concrete primer 24) is applied to smooth the wall surface 1a. In the present invention, the base treatment 24 (concrete primer 24) is applied to the entire surface of the wall surface 1a of the concrete layer 1b (see FIG. 5(b)). A polyurethane-based resin is generally used as the base treatment 24 (concrete primer 24). A one-component resin (applied directly without adding a hardener (polyurethane-based resin)) is used, and the base treatment 24 (concrete primer 24) is dried on the surface 24a before the next step is performed (see FIG. 5(b)).

[0034] The glass mat 25 is cut to a size suitable for application, and the FRP layer 26 and the polyester resin containing a hardener are sufficiently applied to it with a roller or the like, and then the glass mat 25 is attached to the surface 26a. The FRP layer 26 and the polyester resin containing a hardener are further applied to the glass mat 25 with a roller or the like until the glass mat 25 is soaked in the FRP layer 26 and the polyester resin containing a hardener (see Figures 5(d)(e)) (one ply completed). The glass mat 25 is a mat-like material made of glass fibers (see Figure 7).

[0035] The FRP layer 26 and the base polyester resin containing a hardener are applied to the surface 26b (see FIG. 6(f)), and the FRP layer 26 and the base polyester resin containing a hardener are applied to the surface 26b (see FIG. 6(f)) and allowed to blend (surface 26c, see FIG. 6(f)).

[0036] The glass mat 25 is cut to a size suitable for application, and the FRP layer 26 and the polyester resin containing a hardener are sufficiently applied to it with a roller or the like, and then attached to the surface 26c. The FRP layer 26 and the polyester resin containing a hardener are further applied to the glass mat 25 with a roller or the like until the glass mat 25 is soaked in the FRP layer 26 and the polyester resin containing a hardener (see the surface 26c, FIG. 6(g)).

[0037] The FRP layer 26 and the base polyester resin containing a hardener are applied to the surface 26c, and then coated with a roller or the like to give it thickness (surface 26d, see Figure 6(h)) (two plies completed).

[0038] The FRP layer 26 and the base polyester resin containing a hardener are laminated in about two plies, and finally a surface finishing resin 27 (top coat 27) is applied to perform a final smoothing process on the surface layer 27a (lamination thickness: about 2 mm, see FIG. 6(i)). The surface finishing resin 27 (top coat 27) is often made of polyester resin or acrylic urethane resin, which are resins classified by their chemical molecular structure. A mixture of polyester resin or acrylic urethane resin with a hardener and paraffin (paraffin wax) is used, and when applied, the surface layer 27a is finished smoothly (see FIG. 6(i)).

[0039] If there are any parts where the finished surface is insufficient, the surface finishing resin 27 (top coat 27) is applied again, so that abrasion damage of the carrier filter medium 2 is significantly reduced even if the carrier filter medium 2 collides with or comes into contact with the wall surface 1a (see Fig. 1, Figs. 5(a)-(e), and Fig. 6(f)-(i)). The surface layer 27a is made of a carrier filter medium biological treatment tank that can retain and maintain the performance of the biological treatment tank 1, which is the original purpose, regarding the reduction in volume and surface area of ​​the carrier filter medium 2 caused by differences in roughness, hardness, and abrasiveness.

[0040] A state where one layer is attached is called 1-ply, and a state where two layers are attached is called 2-ply. A state where two layers are attached by sandwiching the FRP layer 26 and the polyester resin containing a hardener with the glass mat 25 is called 2-ply (see FIG. 6(i)).

[0041] 2 and 3, in order to prevent water from entering between the concrete surface and the FRP layers, the biological treatment tank 1 is a rectangular parallelepiped or cube, and the bottom surface 29 and side surfaces 30 (bottom surface 29' (surface finishing resin 27 (see FIG. 6(i)) and side surfaces 30' (surface finishing resin 27 (see FIG. 6(i)), see FIG. 3) are fully coated (base treatment 24, 2 plies, and surface finishing resin 27), and the coated upper end is fully coated up to the upper slab surface 28 (base treatment 24, 2 plies, and surface finishing resin 27), and the corners of the bottom surface 29 are provided with haunches 31, 32 ( At the corners of the bottom surface 29' (surface finishing resin 27 (see Figure 6(i))), haunches 32' (surface finishing resin 27 (see Figure 6(i)), see Figure 3) are provided, and the above-mentioned full-surface coating process (base treatment 24, two plies, and surface finishing resin 27) is performed. The upper end of the coating is folded back to the upper slab surface 28, and haunches 31, 32 (at the corners of the bottom surface 29' (surface finishing resin 27 (see Figure 6(i))), haunches 32' (surface finishing resin 27 (see Figure 6(i)), see Figure 3) are provided, thereby creating a structure that reduces the contact friction of the carrier filter material 2.

[0042] 8(a), the carrier filter medium 2 has a diameter E of about 15 mm after 5 years, and the carrier filter medium 2 becomes larger than the holes (diameter E of about 10 mm) in the porous plate screen 6, and the carrier filter medium 2 becomes larger than the holes in the porous plate screen 6 and does not flow out. The FRP layer 26 and the main polyester resin containing a hardener are merely examples of the embodiment, and there are other examples.

[0043] In the present invention, the inner wall surface (wall surface 1a) of the concrete layer 1b of the biological treatment tank 1 is coated with an FRP (Fiber Reinforced Plastics) layer (glass fiber reinforced plastic, no adhesiveness) and a polyester resin base containing a hardener (adhesiveness) (hereinafter, the FRP layer and the polyester resin base containing a hardener are referred to as the "FRP layer 26", see Fig. 5(a) to Fig. 6(i)). This makes the wall surface 1a of the biological treatment tank 1 soft and smooth, and even if the carrier filter medium 2 collides and comes into contact with the wall surface 1a, wear damage is significantly reduced. This is because the glass mat 25 is adhered by coating the polyester resin base containing a hardener (adhesiveness).

[0044] The FRP lamination method involves first filling in the unevenness of the concrete surface with putty and then carrying out base treatment 24. After that, a base polyester resin containing a hardener is applied to a glass mat 25 cut to an appropriate size, which is then affixed to the wall surface 1a, and the resin is applied on top of it to blend in. This is then applied to the entire surface of the concrete wall (one layer applied = one ply).

[0045] Further, by laminating and applying the glass mat 25 to the above, two-layer coating (2 ply), three-layer coating (3 ply), or four-layer coating (4 ply) is obtained. Usually, two to three ply coating is applied.

[0046] After laminating the glass mat 25, a surface finishing resin is applied to perform final smoothing of the surface layer.

[0047] In order to prevent water from penetrating between the concrete surface and the FRP layer and to maintain the adhesive strength of the FRP layer 26, the bottom and sides of the biological treatment tank 1 are entirely covered with the FRP layer 26, and the upper ends of the sides are folded back and layered up to the upper slab surface 28.

[0048] Furthermore, haunches 32, 32' are provided at the bottom corners of the biological treatment tank 1 to smooth the circulation of water and reduce contact wear of the carrier filter medium at the corners.

[0049] As described above, in the biological treatment tank 1, the carrier filter medium 2, which is circulating in the water by air agitation, collides into contact with the wall surface 1a of the concrete layer 1b, causing the carrier filter medium 2 to wear down. Regarding the reduction in volume and surface area of ​​the carrier filter medium 2, which occurs due to differences in roughness, hardness, and abrasiveness between the carrier filter medium 2 and the wall surface 1a of the concrete layer 1b, the biological treatment tank is configured with a carrier filter medium that can retain and maintain the performance of the biological treatment tank 1, which is the original purpose. [Industrial Applicability]

[0050] According to the present invention, it takes 20 to 30 years for the particles to form into small spherical shapes as described above (roughly equivalent to the number of years it takes for a wastewater treatment facility to start operation and require the entire facility to be updated and renovated), and during that time, it is expected that the performance of the biological treatment tank will not deteriorate and problems will be prevented, making it possible to maintain stable treatment performance over the long term. [Explanation of symbols]

[0051] 1 Biological treatment tank 1a Wall 1b Concrete layer 2. Carrier media 26 FRP layers

Claims

1. In a biological treatment tank (1), a carrier filter medium (2) circulating in the water by air agitation comes into collision contact with a wall surface (1a) of a concrete layer (1b), and the carrier filter medium (2) is worn down. Regarding the reduction in volume and surface area of ​​the carrier filter medium (2) caused by the difference in roughness, hardness, and abrasiveness between the carrier filter medium (2) and the wall surface (1a) of the concrete layer (1b), By laminating an FRP layer (26) on the wall surface (1a), the biological treatment tank of the carrier filter material can retain and maintain the performance of the biological treatment tank (1), which is the original purpose.

2. The FRP layer (26) used in the biological treatment tank (1) has a stronger adhesive force to the surface of the wall (1a) of the concrete layer (1b) than other coating waterproofing materials, and is also more resistant to impacts caused by the swirling water flow in the biological treatment tank (1).

2. A biological treatment tank of claim 1, which is capable of retaining and maintaining the performance of said biological treatment tank (1) by maintaining its properties for a long period of time without peeling off.

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