A third successive year of California's worst drought in a century has the Golden State's reservoirs at record lows. Agriculture has been affected, hitting the local economy, while some small communities risk running out of water.
Benedito Braga, President, World Water Council
But business is booming in California's Orange County Water District
(OCWD), through a pioneering wastewater treatment facility that
recycles used water -- or sewage -- and returns it to the drinking
supply.
The plant is expanding production from 70 to 100 million gallons
per day, enough for 850,000 people, around one-third of the county
population. As the OWCD output is mixed with the main groundwater supply
it reaches over 70% of residents.
Sewer water recycled to tap water?
Global problem
As the shortages become more extreme and water supplies are cut, it
has raised awareness that we need to find alternative resources.
Mike Markus, General Manager, Orange County Water District
Mike Markus, General Manager, Orange County Water District
The facility is among the
oldest and largest of its type in the world, and could represent a
model solution for a global problem. The U.N. warns that half the world population
will face water scarcity by 2030, accelerated by climate change and
population growth.
Shortages on such a scale would threaten food
production, as well as a health crisis through increased exposure to
unsanitary water, which already kills millions each year through
waterborne diseases such as cholera and diarrhea.
But the introduction of
reuse systems has been difficult, with a high degree of public
skepticism.
Orange County began recycling water for non-potable use in
the 1970s, but only began contributing to the drinking supply in 2008,
combined with a comprehensive PR and education campaign to allay public
fears.
Operators now feel the
system is well established and ready to scale up. "It's a watershed
moment right now, we're seeing widespread acceptance of these
technologies," OCWD General Manager Mike Markus said.
"As the shortages
become more extreme and water supplies are cut, it has raised awareness
that we need to find alternative resources."
The process works by
re-routing a proportion of the 1.3 billion gallons of waste water
generated in Southern California each day into a three-step treatment.
The first is microfiltration of the treated waste water to remove
solids, oils and bacteria, before the resulting liquid goes through
reverse osmosis, pushing it through a fine plastic membrane that filters
out viruses and pharmaceuticals.
The water is then treated with UV
light to remove any remaining organic compounds, before joining the main
groundwater supply, which must pass strict quality controls to meet
legal standards, and distribution to households.
The OCWD says the water
exceeds all state and federal drinking water standards. Safety has also
been established in pioneering projects around the world.
Water-insecure
Singapore, previously reliant on imports, now delivers 30% of its needs
through the NEWater reclamation facility.
Although only a small amount
is added to its reservoirs, the output surpasses WHO standards for
potable use to the extent that a high proportion is directed for
industrial uses requiring ultra-clean water.
One of the world's
earliest schemes, in Windhoek, Namibia, has been in operation since 1968
and has tackled both shortage and water-borne diseases.
Over half of
the Sub Saharan African population faces water insecurity, and the
greatest health risk, diarrhea, kills over a million people each year in
the region.
But research showed that in the 1970s disease occurred at
lower rates for people supplied by the Windhoek plant than through
conventional treated sources.
The quality from sewage is very good, as good or better than the tap water in any city in the developed world.
Benedito Braga, President, World Water Council
"Standards are stricter
because of the novelty of the technology and process," says Benedito
Braga, President of the World Water Council.
"The quality from sewage is
very good, as good or better than the tap water in any city in the
developed world."
The message is now being
heeded and the model is spreading. California has put $1 billion into
funding recycling for potable use ($800 million of that in low-interest loans), with new initiatives launched in Los Angeles, San Francisco and San Diego.
Texas, parts of which
are also severely affected by drought, aims to generate 10% of all new
supplies through reclaimed water by 2060.
A facility in Big Spring has
introduced the first "Direct Potable Reuse" scheme in the United States
by sending recycled water to the final treatment plant without passing
it through groundwater reserves.
In each case, public
relations are key, as recycled water schemes have been historically shot
down by public disgust at the concept.
This was most vividly shown in
the Australian city of Toowoomba in 2006 when local activists
represented by the group "Citizens against drinking sewage" defeated plans to introduce reclaimed sources, citing health risks and emotive factors.
But Australia also shows the extent to which attitudes have changed.
After a three-year public trial, the city of Perth will receive up to 20% of its drinking water
from reclaimed sources in coming decades, with a reported 76% public
support. A network of similar programs is being established across the
country, according to the Australian Water Recycling Center of Excellence.
Psychologists say the
aversion is deeply held and difficult -- but not impossible -- to
overcome. "The disgust comes from intuitive concepts of contagion," says
Dr. Carol Nemeroff of the University of South Maine, who has studied
reactions to reclaimed water. "It is magical in nature, the same type of
thinking that underlines voodoo practices."
"One of the best ways to
get past it is perceptual cues -- if you can see sparkling fresh, clear
water, and taste it that helps to overcome the concept ... the
contagion type thinking decreases with familiarity," says Nemeroff,
adding that necessity can also be a key driver. "If you're desperate
you'll override anything for survival."
Energy and cost
In Orange County and
other facilities, mixing the output with groundwater is a largely
unnecessary, confidence-building measure to allay public fears.
But as
awareness improves, operators hope to move from indirect to direct
potable reuse, which would bring down energy use and costs, while
avoiding the counter-intuitive step of re-contaminating purified water.
It's the same water now as when dinosaurs walked the earth.
Melissa Meeker, executive director, Water Reuse
Melissa Meeker, executive director, Water Reuse
"The main cost is energy
and that is coming down all the time," says Mike Markus. "Improvements
in membrane technology allow us to use less pressure to do the same
thing."
The energy cost of reverse osmosis has come down by 75% since
the 1970s, he says, while emerging technologies such as Aquaporin may reduce it further. Even now, the cost is favorable compared with desalination or imported water in California.
Markus hopes such
advances will allow for the creation of portable modular units that can
be cheaply transported to the areas of the world with the greatest need.
Campaign group Water Reuse does much of its work in education outreach, through messages such as the "Downstream" concept,
that all water is ultimately recycled.
"It's the same water now as when
dinosaurs walked the earth," says executive director Melissa Meeker.
"It's about understanding the water cycle and how we fit into it. Once
people think about it, they become more open-minded."
If costs continue to
fall and public acceptance continues to grow, waste water can become a
major defense against the projected scarcities of this century.
The
World Water Council projects that recycled sewage will be a normalized
source of drinking water in cities around the world within 30 years, and
much of the infrastructure and technology is already in place. It's up
to us now to get used to it.
SOURCE: http://edition.cnn.com
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