JP2006272218A5 - - Google Patents

Claims (8)

1) First-stage filtration means comprising an ultrafiltration membrane module or a microfiltration membrane module having unique parameters a, b, c
2) Physical washing means for backwashing the first-stage filtration means by feeding water from the permeate side to the treated water side of the first-stage filtration means,
3) A second-stage filtration means comprising an ultrafiltration membrane module or a microfiltration membrane module having specific parameters d, e, and f, which membrane-filters the physical washing wastewater discharged during washing by the physical washing means,
4) When the average turbidity of the water to be treated membrane-filtered by the first-stage filtration means is T ₁ and the average turbidity of the water to be treated-membrane filtered by the second-stage filtration means is T ₂ , the first-stage filtration. The membrane filtration flux F ₁ and permeate recovery rate R _{1 in the} means, and the membrane filtration flux F ₂ and permeate recovery rate R ₂ in the second-stage filtration means are expressed by the following formula F ₁ = aT ₁ ^-b
F ₂ = dT ₂ ^−e
R ₁ = 1-cF ₁
R ₂ = 1−fF ₂
A two-stage membrane filtration system having means for controlling membrane filtration conditions so as to substantially satisfy the parameters a, b, c, d, e, unique to the ultrafiltration membrane module or the microfiltration membrane module. f is 1.5 ≦ a ≦ 10
0.3 ≦ b ≦ 1
0.005 ≦ c ≦ 0.04
1.5 ≦ d ≦ 6
0.1 ≦ e ≦ 1
0.005 ≦ f ≦ 0.02
Is a two-stage membrane filtration system.   The two-stage membrane filtration system according to claim 1, comprising means for controlling the permeate recovery rate R of the entire two-stage membrane filtration system to 99.9% or more.   The two-stage membrane filtration system according to claim 1 or 2, wherein the membrane module of the second-stage membrane filtration apparatus is an immersion type membrane module.   Parameters a, b, c, d, e, and f inherent to the ultrafiltration membrane module or microfiltration membrane module are
5 ≦ a ≦ 8
0.4 ≦ b ≦ 0.8
0.016 ≦ c ≦ 0.03
2.5 ≦ d <5
0.2 ≦ e <0.4
0.01 ≦ f <0.016
The two-stage membrane filtration system according to any one of claims 1 to 3, wherein 1) _F 1 = _aT ^{1 -b} formulas and R ₁ = 1-cF-specific parameters a determined from the _first equation, b, c are,
1.5 ≦ a ≦ 10
0.3 ≦ b ≦ 1
0.005 ≦ c ≦ 0.04
The membrane to be treated having an average turbidity T ₁ is subjected to membrane filtration with a membrane filtration flux F ₁ and a permeate recovery rate of R _1. First stage filtration process,
2) Physical washing step including a step of feeding water from the permeate side of the first-stage membrane filtration device to the treated water side and backwashing the first-stage membrane filtration device,
3) _F ² = _dT 2 ^-e formulas, and R ₂ = 1-fF-specific parameters obtained from the equation ₂ d, e, f are,
1.5 ≦ d ≦ 6
0.1 ≦ e ≦ 1
0.005 ≦ f ≦ 0.02
In the second-stage membrane filtration apparatus comprising an ultrafiltration membrane module or a microfiltration membrane module, the physical washing wastewater having an average turbidity T ₂ discharged from the physical washing step is permeated with a membrane filtration flux F _2. A method of operating a two-stage membrane filtration system having a second-stage filtration step of membrane filtration with R ₂ , wherein the values of the membrane filtration fluxes F ₁ and F ₂ with respect to the average turbidity T ₁ and T _{2 Are} within the range of ± 10% of the following F _1M , and within the range of ± 10% of the following F _2M , and the values of the permeate recovery rates R ₁ and R ₂ are respectively set to the following R within ± 2% of _1M, so that within ± 2% of the following _{R 2M}
F _1M = aT ₁ ^-b
F _2M = dT ₂ ^-e
R _1M = 1-c F _1M
R _2M = 1−f F _2M
And OPERATION bunk membrane filtration system operating method for recovering permeate from the first stage filtration step and the second stage filtration step. The operation method of the two-stage membrane filtration system according to claim 5, wherein the permeate recovery rate R of the entire two-stage membrane filtration system is 99.9% or more. The operation method of the two-stage membrane filtration system according to claim 5 or 6, wherein the membrane module of the second-stage membrane filtration apparatus is an immersion type membrane module. Parameters a, b, c, d, e, and f inherent to the ultrafiltration membrane module or microfiltration membrane module are
5 ≦ a ≦ 8
0.4 ≦ b ≦ 0.8
0.016 ≦ c ≦ 0.03
2.5 ≦ d <5
0.2 ≦ e <0.4
0.01 ≦ f <0.016
The operation method of the two-stage membrane filtration system according to any one of claims 5 to 7, wherein