JP3237337B2 - Bath water purification method and purification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying water in a bathtub such as a bathtub or a small pool.

[0002]

2. Description of the Related Art Conventionally, water in a bathtub is purified using a filtration device and reused as washing water. As this filtering device, a device in which a strainer such as a filter or a wire net is filled in a container is generally used. However, the water in the bath tub contains scale and causes clogging. Therefore, in Japanese Utility Model Laid-Open No. 60-79514, turbulence is caused in the bath water to be purified to remove attached scale.

On the other hand, recently, a system has been developed in which the water in a bathtub or a pool is purified without being discarded and returned again to eliminate waste of water. Microorganisms that decompose organic substances are propagated, and biological purification is performed in addition to physical purification.

[0004]

In the filtration accompanied by the biological purification treatment described above, clogging due to water scale or the like may occur. Therefore, it is conceivable to prevent clogging by generating a turbulent flow as disclosed in Japanese Utility Model Application Laid-Open No. 60-79514. Efficiency will be reduced.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a filter in which the mass transfer coefficient of bath water in a filter filled with a filter medium having a biofilm adhered on its surface is 0.036 [m / h] or more. The shear stress was adjusted to be 1.1 × 10 ⁷ [kg / m · h ² ] or less. Here, in order to adjust the mass transfer coefficient and the shear stress, the flow rate of the bath water, the porosity of the filter medium, or the superficial velocity are adjusted. In addition, a plurality of filters are arranged in series, and when the filter material filled in each filter is different, the mass transfer coefficient of bath water in each filter is changed by changing the flow path cross-sectional area of the filter. Is 0.036 [m / h] or more and the shear stress is 1.1 × 10 ⁷
[Kg / m · h ² ] or less.

[0006]

In the laminar flow state, the treated water flows linearly to the biofilm attached to the surface of the filter medium, so that the biological purification efficiency does not increase. Conversely, excessive turbulence conditions can cause biofilm detachment. Therefore, in order to efficiently perform biological treatment, purification conditions are determined using the mass transfer coefficient and the shear stress as indices.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is an overall view of a circulating purification system to which the method for purifying bathtub water according to the present invention is applied, and FIG. 2 is a longitudinal sectional view of a filtration device used for performing purification according to the present invention. Includes a bathtub 1, a main circulation path 2 for taking out water from the bathtub 1 and returning it to the bathtub 1 again, a sub-circulation path 3 for backwashing, and a filtering device 10 for biologically purifying the bathtub water.

[0008] The main circulation path 2 includes pipes 2a, 2b, 2c, 2
d, 2e, and the auxiliary circulation path 3 is provided with pipes 3a, 2d,
3b, 3c, 2b, 3d and a discharge pipe 3e. That is, the main circulation path 2 and the sub circulation path 3 are 2b, 2d
, A part of 2c as a common pipe, a common pipe 2b with a circulating pump 4, a common pipe 2d with a heater 5 and an ultraviolet sterilizer 6, and a pipe 3a with air provided with a valve. An ejector 8 for introducing air from the pipe 7 is provided.

Further, the conduit 2a, 2b, the three-way valve V ₁ was at the intersection of 3c, the conduit 2b, 2c, the three-way valve V ₂ is the intersection of 3a
A conduit 2d, 2e, a three-way valve V ₃ is the intersection of 3b, the conduit 3c, 3d, are provided three-way valve V ₄ is the intersection of 3e. Incidentally, any pipe switching means such as a spool valve can be used instead of the three-way valve.

On the other hand, as shown in FIG. 2, a filter device 10 is provided with a lid 13 provided with an air vent valve 12 on the upper surface of a cylindrical main body 11.
A bath water inlet 14 is provided on the upper side surface of the main body 11, and a bath water outlet 15 is provided at the center of the bottom of the main body 11. A back washing inlet is provided at the center of the outlet 15. 16
A baffle plate 17 is attached to a portion of the backwashing inlet 16 facing the main body to prevent air from being trapped in the outlet 15 during backwashing. In addition, a drain pipe 18 is provided on the bottom side surface of the main body 11 for storing sludge separated from the filter medium at the time of filtration water passage in a drain portion 25 and discharging the stored sludge.

Further, in the cylindrical main body 11, filter units 21 and 22 in the form of cartridges are arranged vertically one above the other in two stages. These filters 21 and 22 are formed in a bucket shape, and have holes 21a and 22a penetrating in the water flow direction on the bottom surface.

The filter 21 is filled with granular or spherical malt stone as a filter medium 23. In addition, instead of barley stone, Mino active stone, Mino ceramic balls, a filter medium obtained by solidifying a mineral with a cement-based binder, a filter medium composed of diatomaceous earth raw material, a ceramic foam having a three-dimensional network structure, or a fibrous filter medium may be used. . In the filter 22, a filter medium 24 formed by forming activated carbon into a honeycomb shape having a plurality of through holes in a certain direction is placed.

Here, on the surfaces of the filter media 23 and 24, a biofilm composed of microorganisms or the like that decomposes organic substances in the treated water (bath water) propagates and adheres. Suitable conditions are described below.

First, in the filter device 10 of the embodiment, since two filters 21 and 22 are arranged in series, the conditions in the upper filter 21 will be considered with the lower filter 22 removed. The formulas for calculating the shear stress (τ), the mass transfer coefficient (kc), and the first-order reaction rate constant (k) in determining the conditions follow the following (Equation 1), (Equation 2) and (Equation 3). Was.

[0015]

(Equation 1)

(Equation 2)

(Equation 3)

The amount of bath water to be fed into the filter 21 filled with barley stone having an average particle diameter of 4.5 mm in the upper part was gradually increased, and the superficial velocity was increased as shown in Table 1.
At 5 m / h, mass transfer to the biofilm was promoted, the biological purification function worked, and when the superficial velocity was further increased, the biofilm was peeled off at 160 m / h due to shear stress.

[0017]

[Table 1]

Further, the superficial velocity, mass transfer coefficient (kc), shear stress (τ) and first-order reaction rate constant (k) measured at arbitrary 9 points are shown in Table 2 and the mass transfer coefficient (kc) FIG. 3 shows the relationship between and the first-order reaction rate constant (k). Similarly, FIG. 4 shows the relationship between the shear stress (τ) and the first-order reaction rate constant (k). Here, the first-order reaction rate constant (k)
Is represented by the formula, and the larger the k value, the more rapidly organic substances are decomposed.

[0019]

[Table 2]

The organic components brought into the bathtub water must be decomposed within 24 hours, and the next day, the water must be clean again. If the water is dirty from the previous day, it means that purification is insufficient and the dirt accumulates. Therefore, it is a necessary condition that the organic matter brought in that day is almost completely purified within 24 hours. Assuming that the organic matter concentration becomes 1/100 of the initial value in 24 hours, the first-order reaction rate (k) is k = ln (So / St) /
t = ln100 / 24 = 0.19 [l / h]. That is,
It means that the first-order reaction rate (k) must be at least 0.19 or more.

From Table 2 above and FIGS. 3 and 4, the first-order rate constant (k) increases as the mass transfer coefficient (kc) increases, and decreases as the shear stress (τ) increases. As described above, the mass transfer coefficient (kc) and the shear stress (τ) have a fixed relationship with the first-order reaction rate constant (k). To increase the first-order reaction rate constant (k), the mass transfer coefficient (kc) Is 0.036 [m / h] or more and the shear stress (τ) is 1.
1 × 10 ⁷ [kg / m · h ² ] or less, preferably a mass transfer coefficient (k
c) is 0.049 [m / h] or more, and the shear stress (τ) is 1.3 × 10
⁶ Adjust the flow rate of the bath water, the porosity of the filter medium, or the superficial velocity so that it is less than ⁶ [kg / m · h ² ] (k ≧ 0.38).

Next, only the lower filter 22 using activated carbon honeycomb having a cell size of 1.5 mm as a filter medium is set, and conditions in the lower filter 22 will be considered.
In the lower filter 22, as shown in the above (Table 1), the biofilm was peeled off by the shear stress at the superficial velocity of 560 m / h. However, in the lower filter 22, if the superficial velocity was 50 m / h or more, sufficient purification could be performed.

By the way, in the embodiment, the bath water is fed into the filtration device by using a pump having a capacity of 20 liter / min, and the diameter D ₁ of the upper filter 21 is 18 cm. Therefore, the actual superficial velocity is 47 m / h, the mass transfer coefficient (kc) at this time is 0.12 [m / h], and the shear stress (τ) is 1.6 × 10 ⁶ [kg / m · h ² ]. It is. The diameter D ₂ of the lower filter 22 is 16.5 cm, the mass transfer coefficient (kc) is 0.038 [m / h], and the shear stress (τ) is 1.2 × 10 ⁶ [kg / m · h ² ]. It is.

[0024]

As described above, according to the present invention, the mass transfer coefficient of bath water in a filter filled with a filter medium having a biofilm adhered on its surface is 0.036 [m / h] or more and the shear stress is increased. But
Since it was set to be 1.1 × 10 ⁷ [kg / m · h ² ] or less, the shear stress does not peel off the biofilm, and the treated water (bath water) flows to the biofilm appropriately. Therefore, the chance of contact with the biofilm increases, and the biopurification efficiency increases. In addition, for example, when filters are arranged vertically in series, the mass transfer coefficient is set to 0.036 by changing the cross-sectional area of each filter according to the filter medium in the filters without making them the same.
[M / h] or more and the shear stress can be 1.1 × 10 ⁷ [kg / m · h ² ] or less, so that biological purification can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is an overall view of a circulation purification system to which a bath water purification method according to the present invention is applied.

FIG. 2 is a longitudinal sectional view of a filtration device used for performing purification according to the present invention.

FIG. 3 is a graph showing a relationship between a mass transfer coefficient and a first-order reaction rate constant.

FIG. 4 is a graph showing a relationship between a shear stress and a first-order reaction rate constant.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bath tub, 2 ... Main circulation path, 3 ... Sub circulation path, 4 ... Circulation pump, 10 ... Filtration device, 11 ... Device main body, 14 ... Bath water inlet, 15 ... Bath water outlet, 16 ... Backwash inlet, 22, 22, ... filter, 23, 24 ... filter media

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shintaro Hatate 2-1, 1-1 Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Tochiki Kiki Co., Ltd. 2-1-1 Nakajima Totoki Kiki Co., Ltd. (72) Inventor Taimon Kimura 2-1-1 1-1 Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Prefecture Touchi Kiki Co., Ltd. (72) Inventor Takuo Imasaka Fukuoka (1-1) Nakatomi, Inc. 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu City (72) Inventor Takao Teraoka 2-1-1, Nakashima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Prefecture (56) References JP-A-6-335607 (JP, A) JP-A-3-148563 (JP, A) JP-A-6-218386 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 35/02

Claims (2)

(57) [Claims] 1. A method for purifying by supplying bath water to a filter filled with a filter medium having a biofilm adhered on the surface thereof, wherein a mass transfer coefficient of the bath water in the filter is 0.036 [m
/ h] and the flow rate of the bath water, the porosity of the filter medium or the superficial velocity are adjusted so that the shear stress is 1.1 × 10 ⁷ [kg / m · h ² ] or less. Bathtub water purification method. 2. A method in which a plurality of filters filled with a filter material having a biofilm adhered to its surface are arranged in series, and the filter is supplied with bath water to purify the filter. And the mass transfer coefficient of bath water in each filter is 0.036 [m / h] or more and the shear stress is 1.1 × 10
A bath water purifier characterized in that the cross-sectional area of the flow passage of the filter is set so as to be ⁷ [kg / m · h ² ] or less.