Membrane and Desalination Technologies - TCE Moodle Website

172 N.K. Shammas and L.K. Wang
checked at least both before beginning and after completing sampling for the challenge
particulate. Operational data collected prior to initiating sampling should be used to verify
that the flux and recovery are at the required levels. It is also important that the membrane
module(s) undergo direct integrity testing both before and after challenge testing to verify
that the modules were integral during the test.
If the water quality of the test solution matrix is a particular concern, other water quality
parameters should be sampled accordingly. Some examples of other parameters that may be
important in some cases include pH, temperature, turbidity, TDS, TOC, and ionic strength.
The measurement of such water-quality parameters may be most relevant if a molecule
marker is used as the challenge particulate.
All aspects of process monitoring, including what parameters to monitor, how often to
monitor, and the range of acceptable results should be included in the sampling plan for the
challenge test. If any results are outside acceptable tolerances, the challenge test should be
restarted.
4.10.4. Sample Plan Development
The primary purpose of a sampling plan is to define the samples to be collected and provide
an accompanying sampling schedule for the challenge test. A sampling plan should include:
1. Type of sample(s) (i.e., composite vs. grab).
2. Number of feed and filtrate samples to be collected.
3. Sample locations.
4. Sampling interval.
5. Estimate of time required to collect each sample.
6. Sampling equipment required.
7. Sample volume(s).
8. Process monitoring requirements.
The sampling plan should also specify any particular requirements associated with the
analytical technique to be employed, as well as procedures for shipping the sample(s) if they
are to be analyzed at an off-site laboratory. Samples should be collected, preserved, stored,
prepared, and analyzed using methods and techniques appropriate for the challenge particulate.
Sampling should not begin until the system has stabilized (i.e., reached equilibrium
concentration). Most test apparatuses achieve greater than 90% of equilibrium concentrations
after three hold-up volumes have passed through the system. Thus, the system hold-up
volume and feed flow can be used to estimate the point at which the system is near
equilibrium and thus the time at which sampling can begin. Both the hold-up volume and
time required for system stabilization should be included in the sampling plan.
4.11. Analysis and Reporting of Challenge Test Results
After challenge testing is completed for a particular product, the results must be analyzed
to determine the established removal efficiency of the module (i.e., LRV C-test) for the
purposes of LT2ESWTR compliance. The following subsections provide guidance regarding