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Membrane Systems Planning and Design 335
Most of the information contained in this section is generally applicable to both microfiltration
(MF)/ultrafiltration (UF) and nanofiltration (NF)/reverse osmosis (RO) systems
(2–7). Distinctions between the two systems are noted where differences occur. Pilot testing
for membrane cartridge filtration (MCF) systems is typically simpler relative to testing other
types of membrane filtration and is often performed simply to verify the replacement
frequency and productivity for the filters. Consequently, pilot testing MCF systems is not
specifically addressed in this chapter. However, MCF piloting guidelines are generally
similar to those for MF/UF with the exception of references to cleaning intervals, since
membrane cartridges are not typically cleaned and instead disposed off when fouled.
2.1. Planning
The planning phase prior to implementing pilot testing is an important component of an
overall pilot test program. Careful planning helps ensure that all the pilot test objectives are
achieved both efficiently and economically without unexpected delays. The most important
element of the planning process is the development of a comprehensive pilot test protocol
specifying how the testing should be conducted. This protocol should include not only instructions
for carrying out the testing, but also specific testing objectives and strategies for optimizing
performance in terms of flux, backwashing, and chemical cleaning. A plan for collecting
water quality, integrity test, and microbial (where applicable) data should also be incorporated
in the test protocol. In addition, it is recommended that the pilot protocol be developed in
conjunction with the state to ensure that any particular state requirements are satisfied.
In addition to the test protocol, a number of other planning considerations should be taken
into account. For example, it should be determined whether the pilot test units can be
provided by the membrane manufacturers at no cost, rented or custom-fabricated, as budget
constraints allow. Also, once the particular membrane filtration systems to be tested are
selected, the utility requirements (i.e., water, electricity, and/or air) for the pilot units must be
accommodated at the test site. Appropriately sized plumbing connections should be provided
for the feed, filtrate, and concentrate streams, and provisions must be made for the disposal of
backwash (for MF/UF) and chemical cleaning residuals. Labor requirements for operating the
pilot units should be estimated, and it is also important to ensure that the designated testing
site has sufficient area to accommodate all the units to be tested. One consideration that is
sometimes overlooked is shipping the pilot units; the proper equipment for loading and
unloading the pilot units must be available at the testing site or be provided with the unit
(s). Special attention in the planning phase should be given to process considerations such as
scalability, screening appropriate membrane filtration systems to test, and test scheduling.
2.1.1. Process Considerations
It is important that the pilot process be representative of the full-scale system. For example,
if pretreatment is part of the planned full-scale process, then the pilot process should
incorporate similar pretreatment. Likewise, piloting should also accommodate production
(e.g., filtration) and intermittent (e.g., backwashing) design considerations to the extent that
these parameters have been defined prior to the pilot testing phase. Thus, if it has been