Imagine a situation in which you can take advantage of a cost-effective
way to maximize your reverse osmosis system's performance while minimizing
The opportunity is available and it is known as membrane
regeneration--a process that extends membrane life and increases the time
interval between cleanings at a fraction of the cost of membrane replacement.
In many cases, membrane regeneration can double or triple membrane element
life, significantly reducing replacement costs while effective restoring plant
It seems simple enough--make use of membrane regeneration
and save money.
Ironically, it has long been known that many reverse osmosis
membrane elements are thrown away too soon, essentially eliminating any
opportunity for cost savings.
Fortunately in August 2002, a new facility designed
specifically for regenerating membrane separation elements opened in
Engineered for applications wherein the elements can no
longer be cleaned effectively in the field and for those with operating budgets
that do not provide for the purchase of new elements, the Bakersfield membrane
regeneration facility is an economical and practical way for membranes to be
regenerated to maintain full productivity.
Located at the production complex for GE Betz, the membrane
regeneration facility can restore quality performance, extend membrane life and
increase the time interval between cleanings at a fraction of the cost
associated with membrane replacement.
This state-of-the-art facility has the ability to process up
to 60 membranes continuously for 24 hours a day, which allows the facility to
produce better than average turn-around times when compared to other
regeneration facilities in North America.
"What makes us unique is the volume of membranes we can
treat, meaning a quick turnaround time and the automated equipment that gives
us more control over the process which improves our ability to clean membranes
when others cannot," Brian Banerdt, plant manager of the Bakersfield
complex told Water & Wastes Digest.
Additionally, the facility can help to increase permeate
flow by incorporating a corresponding decrease in differential pressure. This
helps the off-site cleaning process minimize downtime and eliminate chemical
purchase, handling and disposal problems.
In discussions with WWD, Banerdt emphasized that the
Bakersfield regeneration facility has been specifically engineered to decrease
turn-around times and improve restoration effectiveness, a process that has
been utilized often.
Within the past year, Banerdt acknowledged that the GE Betz
facility has worked with numerous customers, each of which have their own
specific requirements according to their needs, a few of which WWD reviews in
While researching this article, Banerdt offered WWD a number
of different testimonials touting the Bakers-field membrane regeneration
facility. WWD examines four of these applications, each of which exemplify the
diverse customer needs addressed at the facility.
The first application involves the city of Calpine, Ala.,
which sends the Bakersfield facility 50-100 membranes every 3-4 months.
According to Banerdt, the facility preserves the membranes and returns them
regenerated within a 2-3 week period. Calpine city officials are satisfied with
the service because in addition to their membranes being cleaned, their
contract price includes shipping costs.
Another application involves Ionics Ahlfinger Water, which
has been a customer of membrane regeneration for over five years but has been
specifically using the Bakersfield plant the past year. Again, Ionics is
content with the service due to quick turn around time and pricing, but it is
their close proximity to the Bakersfield plant that allows for the membranes to
be shipped directly back to Ionics' customers.
The Tennessee Valley Authority (TVA) is one the Bakersfield
facility's larger customers as they send an average of 100 membranes every
month to be cleaned. The Bakersfield facility cleans membranes for four
different TVA locations: Cumberland City, Tenn.; Gallatin, Tenn.; New
Johnsonville, Tenn.; and West Paducah, Ky. Each of these locations consistently
averages about 50-100 membranes every 1-2 months.
The final application is unique, as it is located outside of
the U.S., in Saskfreco, Canada. The facility's most frequent membrane cleaning
customer from Canada tried a number of different membrane regeneration plants
before settling on the quality and performance delivered by the Bakersfield
As part of the membrane regeneration process, the
Bakersfield facility can process spiral wound, thin film, and cellulose acetate
reverse osmosis, ultrafiltration and nanofiltration elements from all major
suppliers in a full range of sizes.
According to GE Betz, the regeneration involves both
physical and chemical processes. In a typical sequence, the elements are soaked
in proprietary chemicals and cleaners followed by treatment in the regeneration
loop. This recirculates heated cleaning solutions through membrane feed
passages while importing high shear forces to the membrane surfaces, restoring
performance to even the most severely fouled elements. The plant incorporates
automated equipment with the ability to control all aspects of the regeneration
process such as temperature, flow and flow pressure for example.
"Our closely controlled temperatures and proprietary
mechanical features and specialty chemicals can provide results compared to the
use of clean-in-place equipment at the customer's site," Banerdt told WWD.
After cleaning, the elements are wet tested using
dechlorinated, municipally treated water, and performance results are
normalized to the element manufacturer's standard test conditions.
Traditionally, membrane fouling reduces permeate flow and salt
rejection, and increases differential pressures. Studies show that regeneration
typically results in a 40% increase in permeate flow, a 38% decrease in
differential pressure and a 3% increase in salt rejection. For a system
containing these elements, operating pressure could be reduced by 100% to
maintain an equivalent pre-regeneration permeate flow. If the same system were
operating at a 75% recovery on a feed stream that contained 1,000 ppm total
dissolved solids, permeate salt passage would decrease from 3.3% to 0.4%
When regeneration is combined with effective pre-filtration,
field cleaning and antifoulant use, significant cost savings are possible. The
more effective the pre-treatment process, the greater the savings because the
frequent of regeneration is reduced.
Recently, the membranes used in a reverse osmosis program at
a Belgian chemical plant were so fouled that normal cleaning procedures could
not restore their effectiveness. The company was faced with the prospect of
having to buy 92 new membranes at a total cost of $92,000.
GE Betz recommended shipping the membranes to their membrane
regeneration facility in Edinburgh, Scotland, which offers similar capabilities
to the plant in Bakersfield.
After a visual inspection, weighing and wet testing, it was
determined that 89 elements would benefit from a proprietary cleaning process
for restoring quality performance and extending membrane life. At the end of
the process, 83 membranes were judged sufficiently regenerated to be used again
in the system. Only six elements had to be rejected because they still
exhibited high differential pressures.
After deducting the shipping and regeneration costs, the
cost avoidance saving for not having to replace 83 membranes was $61,455.
More information on GE Betz's Membrane Regeneration Facility
can be found at www.gebetz.com .
Membrane regeneration facility in Bakersfield, Calif., boasts quick turnaround time; customers agree