Method for testing separation modules
View Patent ↗New methods and apparatus are described for assessing the integrity of a separation module or filtration system. A principle embodiment concerns use of a transient pulse of challenge species to probe a spiral wound module. The resulting time-dependent concentration of challenge species in the permeate is detected, recorded, and compared to a reference. An apparatus is further claimed for detecting permeate conductivity at multiple points within the permeate collection tube of a spiral wound module. Also disclosed is a process whereby the permeate stream from a filtration system is concentration by a high recovery membrane apparatus prior to measurement of challenge species concentration.
1. A method for measuring conductivity of permeate liquid at a plurality of locations along a permeate tube of a spiral wound module comprising the steps of:
i) locating a probe device within a permeate tube of a spiral wound module, wherein the probe device comprises an array of conductivity cells mounted along a support structure,
ii) introducing a feed liquid into the spiral wound module, and
iii) measuring the conductivity of the permeate liquid.
2. The method of claim 1 wherein the step of measuring conductivity is performed simultaneously at several positions along the permeate tube.
3. The method of claim 2 wherein the step of measuring conductivity is performed at least four positions along the permeate tube.
4. The method of claim 1 wherein the feed liquid comprises a charged species.
5. The method of claim 4 wherein the charged species are selected from divalent ions.
6. The method of claim 1 wherein the probe device is axially relocated during the step of measurement.
7. The method of claim 1 wherein the spiral wound module is connected in series to at least one additional spiral wound module.
8. A method for measuring conductivity of permeate liquid at a plurality of locations along a permeate tube of a spiral wound module comprises the steps of: locating a probe device within a permeate tube of a spiral wound module wherein the probe device comprises an array of conductivity cells mounted along a support structure and measuring the conductivity of the permeate liquid during the following steps:
i) introducing a first feed liquid under pressure into the spiral wound module,
ii) introducing a second feed liquid under pressure wherein the second feed liquid comprises a challenge species, the concentration of the challenge species being at least twice as high as compared to the first feed liquid,
iii) introducing a third feed liquid under pressure wherein the successive introduction of the second and third feed liquids results in a pulse of challenge species characterized by a concentration profile in time for the challenge species having FWHM of less than four minutes.
9. The method of claim 8 wherein the pulse of challenge species within the spiral wound module is characterized by a FWHM of less than forty seconds and the relative concentration of the challenge species within the permeate fluid is measured at intervals of less than 2 seconds.