Water & Wastewater Asia January/February 2022

NEWS
US LARGEST ION EXCHANGE PFAS TREATMENT
FACILITY COMMENCES OPERATION IN
YORBA LINDA
The Orange County Water District (OCWD)
and the Yorba Linda Water District (YLWD)
has begun operating what is dubbed the US
largest ion exchange (IX) treatment plant to
remove per- and polyfluoroalkyl substances
(PFAS) from local well water.
PFAS are a group of thousands of manmade,
heat-resistant chemicals that are prevalent
in the environment and are commonly
used in consumer products to repel water,
grease, and oil. Due to their prolonged use,
PFAS are being detected in water sources
throughout the US, including the Orange
County Groundwater Basin, which supplies
77% of the water supply to 2.5 million people
in north and central Orange County. Despite
playing no role in releasing PFAS into the
environment, water providers must find ways
to remove it from their local water supplies.
Steve Sheldon, president of OCWD,
commented: “We worked closely with YLWD
to rapidly construct this treatment facility to
remove PFAS from groundwater and ensure
that they continue to meet all state and federal
drinking water standards.”
YLWD, one of 19 water providers that pump
water from the groundwater basin, has
all 10 of its groundwater wells impacted
by perfluorooctanoic acid (PFOA) and
perfluorooctane sulfonate (PFOS), prompting
it to temporarily shut down wells and
transition to purchasing imported water
sourced from the Colorado River and
Northern California. These wells were among
dozens of wells throughout Orange County
that were removed from service in 2020 after
the state of compounds no longer produced
in the US.
Located at the existing YLWD headquarters
in Placentia, the PFAS Treatment Plant uses
an IX treatment system made of highly porous
resin that acts like magnets that adsorb and
hold onto contaminants. It consists of 11 IX
systems, a 25 MGD booster pump station
Yorba Linda Water District is a public agency serving
residents of Yorba Linda
and an upgraded onsite chlorine generation
system. During treatment, contaminants
such as PFAS are removed from the water
before it goes into the distribution system.
Construction began last March, and the
facility will be capable of treating up to 25
million gallons per day.
Phil Hawkins, president of YLWD, concluded:
“Bringing this treatment facility online is
very important for our customers. It means
YLWD can safely increase its use of local
groundwater, which is less expensive and
more reliable than imported water.”
FIRST GLOBAL RIVER DATABASE DOCUMENTS 40 YEARS OF CHANGE
The database of four decades of changes in
the world’s largest rivers could become an
important tool for urban planners seeking to
better understand river deltas and the large
portion of Earth’s population that lives there.
The database, created by researchers at The
University of Texas at Austin, uses publicly
available remote sensing data to show how
river centrelines have moved over the past
40 years. The information can be used to
predict how rivers and their deltas will move
over time, and will help policymakers manage
population density and future development in
these areas.
“When we think about river management
system, we have very little to no information
about how rivers are moving over time,” said
Paola Passalacqua, who leads the ongoing
analysis. The research is funded by the US
National Science Foundation (NSF), and is
published in Proceedings of the National
Academy of Sciences.
Laura Lautz, programme director in NSF’s
division of earth sciences, added: “The
availability of abundant satellite data, coupled
with advances in machine learning, have
made it possible to map actual channel
migration rates, and how river deltas are
changing through time, at a global scale that
wasn’t possible before.”
The database includes three US rivers –
the Mississippi, the Colorado, and the Rio
Grande. Although some areas of these
rivers’ deltas have experienced migration,
overall, they are mostly stable, the data
show. Aggressive containment strategies
to keep the rivers in their places, especially
near population centres, play a role in that,
Passalacqua said.
Average migration rates for each river delta
in the database help identify which areas
are stable and which are experiencing
major river shifts. The researchers also
published more extensive data online that
include information about how different
segments of these rivers have moved over
time. The information could help planners
see what’s going on in rural areas against
urban areas.
WATER & WASTEWATER ASIA | JANUARY/FEBRUARY 2022 13