Claims
- 1. A method of predicting a logarithmic reduction value for a membrane filtration system, the membrane filtration system having a membrane, the membrane having a bubble point, a first side, and a second side, and the logarithmic reduction value being defined by the formula: LRV=log10(CinfCeff)(1)wherein LRV is the logarithmic reduction value, Cinf is a concentration of particle in an influent, and Ceff is a concentration of particle in an effluent, the method comprising the following steps:(i) measuring a flow rate of liquid filtrate through the membrane; (ii) measuring a membrane bypass flow rate using an integrity test measurement, wherein the membrane bypass flow rate is the flow rate through leaks and defects in the membrane; and (iii) estimating the logarithmic reduction value using a ratio of the filtrate flow rate and the membrane bypass flow rate as follows: LRVest=log10(QfiltQbypass),wherein LRVest is an estimate of the logarithmic reduction value, Qfilt is the filtrate flow rate, and Qbypass is the membrane bypass flow rate.
- 2. The method of claim 1 wherein said integrity test method comprises the steps of:(i) wetting the membrane; (ii) applying a gas pressure to the first side of the membrane below the bubble point of the membrane; (iii) measuring a gas flow across the membrane, said gas flow including a diffusive flow through the membrane and a flow through leaks and defects in the membrane; and (iv) determining the flow through leaks and defects in the membrane by subtracting the diffusive flow through the membrane, said diffusive flow being determined by a calculation or a measurement of a fully integral membrane, said gas flow through leaks and defects in the membrane being indicative of the membrane bypass flow rate.
- 3. The method according to claim 2 wherein the gas flow is measured by monitoring a temporal decay of the gas pressure applied to the first side of the membrane.
- 4. The method according to claim 2 wherein the gas flow is measured by surrounding the second side of said membrane with a volume of a fluid and measuring a displacement of said fluid resulting from said gas flow.
TECHNICAL FIELD
This application is a continuation of application Ser. No. PCT/AU98/00387, filed on May 26, 1998. The present invention relates to a method of predicting logarithmic reduction values in a filtration system and use of such values for control and monitoring of an operating filtration system.
US Referenced Citations (15)
Foreign Referenced Citations (4)
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3428307 |
Feb 1986 |
DE |
2 253 572 |
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GB |
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Non-Patent Literature Citations (1)
Entry |
Copy of International Search Report (PCT/AU96/00144 by Examiner Olliey). |
Continuations (1)
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Number |
Date |
Country |
Parent |
PCT/AU98/00387 |
May 1998 |
US |
Child |
09/386899 |
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US |