Large-scale wastewater purification systems supplement natural water supplies, Water Efficiency magazine, by Don Talend, brand storytelling, content management and demand generation expert. Water engineering industry

1. JANUARY/FEBRUARY 2011
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2. 24 WATER EFFICIENCY J a n u a r y / F e b r u a r y 2 0 1 1
C
ombine a highly popu-
lated county in south-
ern California and the
region’s climate and
ongoing challenges to
provide sufficient potable water sup-
plies, and the need to “think outside
of the box” arises. The Orange County
Water District (OCWD) and Orange
County Sanitation District (OCSD)
are combining their expertise to
undertake an ambitious $481-mil-
lion Groundwater Replenishment
System (GWRS) project that recycles
the wastewater from the sanitation
district’s 21 cities. The world’s larg-
est planned indirect potable water
reuse project will boost long-term
water resources for about 2.4 million
people in 21 California cities, includ-
ing Anaheim, Santa Ana, and parts of
Irvine.
Technological advances in water
purification are allowing some water
authorities such as the OCWD to
make good use of wastewater—some-
thing that previously was not consid-
ered a resource.
By January 2008, the first phase of
the GWRS was marked by the startup of
a new $300-million, 70-million-gallon-
per-day (mgd) water treatment facil-
ity in Fountain Valley, CA. The facility
replaces a 5-mgd reclamation plant at
the site known as Water Factory-21 that
was built in the 1970s. The new facility
features a submerged membrane system
that is upstream from a reverse osmosis
(RO) unit and an advanced oxidation
system that utilizes ultraviolet (UV) light
plus hydrogen peroxide. The $27-mil-
lion microfiltration system is the largest
in the Americas and one of the largest
in the world. The project was awarded
the 2009 ASCE (American Society of
Civil Engineers) Outstanding Civil
Engineering Achievement Award, the
US Environmental Protection Agency’s
Organic Growth—
in a Manner of Speaking
When natural resources aren’t
enough, some purveyors supplement
with recycled wastewater using
large-scale treatment systems.
By Don Talend
Orange County Water District

3. w w w . w a t e r e f f i c i e n c y . n e t WATER EFFICIENCY 25
(EPA) Clean Water State Revolving Fund
“PISCES”Award, the American Council
of Engineering Companies Grand Con-
ceptor Award and “Golden State”Award
of Excellence, and the Stockholm 2008
Industry Water Award.
The GWRS is anticipated to
increase in capacity in two subse-
quent phases, from 70 to 100 mgd, and
ultimately, to 130 mgd, reports Mike
Markus, general manager for OCWD.
Currently, the groundwater replenish-
ment is serving as a supply for indirect
potable water use, and over the long
term it is expected to ease the burden
on current water supplies that have
been deemed insufficient to meet future
needs. According to the two agencies,
the use of the GWRS will consume only
50% as much energy as would be needed
to import water from northern Califor-
nia, and 66% of the energy that would
be needed to transfer water from the
Colorado River. Additionally, the system
will reduce the amount of wastewater
that Orange County discharges to the
ocean via outfalls.
The project, which was in the design
phase of the expansion from 70 to 100
mgd as of mid-2010, has been planned
for years. The OCWD conducted a pilot
study of three different microfiltration
systems, from Zenon, Pall, and Memcor,
and had the three manufacturers submit
a proposal to the district back in the
early 1990s. After selecting the Mem-
cor CMF-S system, the OCWD had its
design engineer incorporate the Memcor
system into the design. The more costly
alternative, Markus explains, would have
been designing around each of the three
microfiltration systems, and then having
the general contractor choose a system.
The county awarded Siemens Water
Technologies the microfiltration system
contract in 2002.
In the end, the Memcor system was
chosen, mainly because it was projected
to provide a lower life cycle cost in the
pilot study. The system will also be used
in the second and third project phases
for the sake of continuity, Markus
reports. The Memcor CMF-S system
inside the facility has 26 cells of micro-
filtration media. Each cell has 19 racks,
each of which contains 32 membrane
modules. All told, the current system has
about 15,800 membrane modules. Each
cell is fitted with its own filtration pump
that draws water through the membrane
fibers. The modules are located below
the raw water elevation, allowing use of
the hydraulic gradient and eliminating
the need to pump water into the mem-
brane cells.
The Memcor system mainly re-
moves suspended solids from the source
water, which has a typical total suspend-
ed solids (TSS) content of 8.94 milli-
grams per liter (mg/l). The treated water
has a non-detectable TSS content, tur-
bidity of 0.156 nephelometric turbidity
units (NTUs), and a total dissolved sol-
ids (TDS) level of 45.37 mg/l, according
to Markus. Following the microfiltra-
tion, the effluent enters a Hydranautics
ESPA (Energy-Saving Polyamide) RO
membrane system via high-pressure feed
pumps that force the effluent through
the membranes. This system treats the
water for dissolved minerals, viruses,
and pharmaceuticals. Finally, a combi-
nation of hydrogen peroxide and a Tro-
janUVPhox (Ultraviolet-Photolysis and
UV-Oxidation) system—equipped with
a pressurized UV light reactor that uti-
lizes high-output monochromatic amal-
gam UV lamps—destroys some very
small remaining organic compounds
and renders some others neutral.“We’ve
been gathering data over the past three
years and getting non-detect levels on
pharmaceuticals, endocrine disruptors,
and [volatile organic compounds], so it’s
been an extremely effective process,” says
Markus of the final treatment process.
Following treatment, the water is
pumped into recharge basins or barrier
wells, where it is blended with other
groundwater, and then travels through
the soil, which provides additional natu-
ral treatment of the water.
The expansions will proceed as
outside financing becomes available,
Markus reports. So far, funding sources
have included $92 million in grants;
$20 million from the US Bureau of
Reclamation’s Title XVI water reclama-
tion and reuse program; $67 million
from California’s Safe Drinking Water,
Clean Water, Watershed Protection, and
Flood Protection Bond Act; $5 million
from the State Water Resources Control
Board; and a 21-year, $3-million opera-
tions and maintenance subsidy from the
Metropolitan Water District of Southern
California. The project is also financed
by about $180 million in loans.
The much-needed project will al-
low the OCWD to address its potable
water supply challenges at the local level.
“We live in a desert here in southern
California, and sometimes people forget
that,” says Markus.“We are very highly
dependent on outside imported water,
either from the Colorado River or from
northern California. The northern
California supplies are restricted because
of environmental considerations for
some endangered species—they’re not
pumping as much water from North to
South, and so that has forced agencies to
develop local projects, and it’s through
these local projects that we helped de-
velop a dependable local water supply.”
The unique partnership between
OCWD and the county sanitation
district addresses mutual needs, Markus
points out.“They [the sanitation dis-
trict] had a need to build a second ocean
outfall to handle some of their peak
wet-weather events. When they get too
much water in their system during the
winter, it exceeds the capacity of their
existing ocean outfall. The two agencies
got together and the sanitation district
told us that if we were to build our facil-
ity such that we could treat their peak
wet-weather events, they would kick
in half the cost of capital. Even though
we are two different agencies and have
two different missions, we work very
closely together. Rather than wasting
that wastewater—that resource, if you
will—to the ocean, they gave it to us,
and then we recycled it and purified it,
and it became a source of water supply
for the groundwater basin.”
Tertiary Treatment and a
Focus on Equalization
A second example of two water man-
agement entities joining forces for a
win-win partnering arrangement is the
Encina Wastewater Authority (EWA)
and the Carlsbad, CA, Municipal Water
District sharing the costs for the 4-mgd
Carlsbad Water Recycling Facility
and equalization system between that
plant and the adjacent Encina Water
Pollution Control Facility.
EWA is jointly owned by six public
agencies, including the Carlsbad district,
and operates the Carlsbad facility. The
43-mgd Encina facility provides primary
and secondary clarification treatment of
wastewater for the agencies. The Carlsbad

4. 26 WATER EFFICIENCY J a n u a r y / F e b r u a r y 2 0 1 1
facility was constructed to provide ter-
tiary treatment of the wastewater so that
it can be recycled for irrigation by several
customers, including local golf courses.
The Carlsbad facility has its origin
in an effort by EWA to expand the
equalization capability of the Encina
facility’s secondary treatment process,
explains John Jardin, EWA’s director of
operations, who reports that the latter
facility’s outfall presented a bottleneck.
The best way to expand outfall was to
expand equalization, Jardin points out,
so in 2001 EWA began constructing
two 3.5-mg open-tank reservoirs, an
elaborate equalization pump scheme,
two 300-horsepower (hp) and two
150-hp emergency equalization pumps,
a combined pump station, and standby
generation for emergency high-surge
peak storm flows. Around the same
time, the Carlsbad district was conduct-
ing a reclaimed water master plan study.
Both entities had seasonal needs
that made a joint effort a win-win ar-
rangement. Storing water during the
winter would allow EWA to address its
outfall challenge. The Carlsbad district
would benefit from having a steady sup-
ply of secondarily treated water from the
Encina facility during the summer, when
irrigation demand is high.“So Carlsbad
jumped in on top of our project after we
were already into the process and split
some of the costs,” recalls Jardin. The
two entities share the tanks and a com-
bined pump station located at a lower
elevation than the tanks on the same
property. The pump station has four
pumps, two for sand filtration upflow
filters and two for a Memcor micro-
filtration system; Jardin explains that
treatment is necessary when the water
is stored in the equalization system for
long periods.
At the Encina facility, more than
5 million gallons of wastewater flow
through bar screens that screen out
large debris every day.
The wastewater then
flows into a chamber
where grit and sand are
removed. Ferric chloride and anionic
polymers enhance settling in a chemical-
ly enhanced primary treatment process
that is designed to reduce biological oxy-
gen demand by roughly half and remove
75–80% of TSS. In addition, hydrogen
peroxide is injected for odor control
during this stage. Following primary
treatment, the effluent is diverted to two
secondary aeration basins equipped with
bubble diffusion membranes. Com-
pressed air is pumped into these basins
to spur microorganism growth. These
microorganisms eat tiny pollutants,
naturally purifying the wastewater. The
wastewater then flows to clarifiers, where
the microorganisms settle to the bottom.
Water that is not sent to the ocean is sent
for further treatment to other facilities
such as Carlsbad.
Water 3 Engineering Inc., Irvine,
CA—which was recently acquired by
RMC Water and Environment—was
hired to assist with the implementation
of the new equalization infrastructure
and startup of the Carlsbad facility. The
facility’s tertiary process uses an upflow
filter with granular media and a Micro-
filtration Reverse Osmosis (MFRO) sys-
tem. One set of pumps diverts effluent
to the granular media and the other set
of pumps sends it to the MFRO system
for desalination. After the granular/
MFRO process, effluent passes through
a decarbonator that blows air through it
and the final step is chlorina-
tion with sodium hypochlo-
rite. Jardin reports that the
sand filter is sufficient for
reducing the TDS to the
threshold level, but the RO
and microfiltration systems
are available for use during
peak flows.
The recycling system
will yield financial as well as
environmental benefits for
the City of Carlsbad, notes
Scott Goldman, principal at
RMC Water and Environ-
ment. Less water will have to
be imported from a distance
and the city gets rebates from
the San Diego County Water
Authority, which offset the
cost of developing the treatment facility.
Recycled water also retains nutrients that
are beneficial for irrigation, such as nitro-
gen, and its use typically is not included
in water restrictions, Goldman adds.
Increasing Potable Supply Via
Immersed Membranes
An example of a water purveyor using
new treatment technology to manage
an increase in the potable water sup-
ply is the Miller, SD-based Mid-Dakota
Rural Water System. Kurt Pfeifle, gen-
eral manager for the water district,
reports that a 9-mgd potable water
treatment plant north of Pierre, SD,
was essentially maxed out during a hot
summer of 2006. Also, according to
the US Geological Survey, the percent-
age of South Dakota’s population that
uses water from public systems has
increased at the expense of private well
systems in previous years.
The district serves about 5,100
customers, in all or part of, 13 counties
in central South Dakota. Pfeifle recalls
that ambient temperatures ranged
from the 90s to over 100°F that sum-
mer, necessitating the district to run
the plant at around 8.5 mgd for several
The OCWD
and OCSD are
combining their
expertise for a
GWRS project.
SteveCriseCourtesyofAWWA

5. w w w . w a t e r e f f i c i e n c y . n e t WATER EFFICIENCY 27
weeks; one day’s consumption was 8.9
mg. “When we built the plant back in
1995–96, we had actually planned for
some expansion in the future—we just
didn’t think it would come a few years
later,” he says.
The major barrier to expanding the
36,000-square-foot plant’s treatment
capacity was expanding the building,
however. Pfeifle explains that the soils
in the area consist largely of oil-filled
shale that is susceptible to expansion
and contraction, causing structural
stability problems. When the plant was
originally built, concrete piers were
drilled all the way down to the bedrock.
“Back in 1995–96, we had planned
for an expansion, but that plan actually
envisioned an expansion of the conven-
tional [sand and coal] filtration system,”
says Pfeifle.“As we fast-forward 15 years
later, the technology has changed.”
The district looked at several
systems, including GE’s ZeeWeed
immersed membrane technology, to
replace the existing treatment system.
“When we realized that we needed to
do an expansion, we engaged our engi-
neers in conceptual design studies and
we looked at various filtration systems,”
he says. “The membranes were brought
into the picture because the engineers
kept themselves abreast of new technol-
ogies. As we did our conceptual studies,
the thought of being able to put a new
filtration system in without adding a
lot of brick and mortar became pretty
attractive to us. Then we engaged some
pilot studies of a couple of different
membrane filtration systems.”
Ultimately, the district selected
the ZeeWeed system to retrofit the
existing filter cells at the plant. Under
a $3.4-million contract with GE, five
trains of ZeeWeed-1000 immersed
membranes will treat source water
from the Missouri River, allowing an
increase in the plant’s potable water
capacity from 9 mgd to 13.5 mgd.
Under a second $6.37 million contract,
John T. Jones Construction, Fargo, ND,
is upgrading process pipework and
constructing a 6,000-gallon-per-minute
booster station. Once the project is
completed in November 2011, the plant
will be the largest ultrafiltration mem-
brane facility in the state.
“One of the reasons why we chose
the membrane system is that we didn’t
have to add a lot more brick and mortar
to the existing plant—we actually put
the new membrane system into the ex-
isting footprint of the plant,” points out
Pfeifle.“I think it would even be safe to
say that once all of the membrane filters
are put into place, we’ll wind up with
some additional square footage, at least
in the process area. I was actually quite
surprised that we could gain that much
more in capacity and, in the process area
of the water treatment plant, actually
gain some square footage for storage and
other uses.
“The membrane technology has
been around for quite a while, but
my understanding is that it was more
prominent in the wastewater industry
before, and it’s just in the past few years
that it has made the transition into the
drinking water industry. It’s a fairly new
technology, at least from our standpoint.
But, having said that, it’s also an exciting
technology. Our understanding of it is
that it’s a better quality of water that
you would get out of a traditional sand
filtration system.”
The new system will easily meet the
state’s lowest cryptosporidium thresh-
old. The district was required to test its
source water for 24 consecutive months
for purposes of categorizing the system
in one of four bins. The system was
placed in Bin 1, which has no additional
treatment technique requirements, in
contrast to bins 2, 3, and 4, which have
increasing additional treatment tech-
nique requirements. The system average
over the 24-month sampling period was
0.004 oocysts per liter versus the Bin 1
threshold of less than 0.075 oocysts/L.
Pfeifle reports consistent turbidity read-
ings of 0.03 NTUs since the new system
was installed, compared with readings of
0.04–0.15 NTUs yielded by the previous
filtration system. WE
Don Talend is a print and e-content
developer specializing in technology
and innovation.
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