[Southern_AZ_MWS] From Sewage, Added Water for Drinking
CathyMullan at cox.net
Tue Nov 27 08:16:43 MST 2007
I wonder if anyone has really studied the impact of injecting treated
"after a hard scrubbing with filters, screens, chemicals and
ultraviolet light" I would be interested in knowing if this is enough
to scrub out personal care products residue from the water. Cathy
November 27, 2007
From Sewage, Added Water for Drinking
By RANDAL C. ARCHIBOLD
FOUNTAIN VALLEY, Calif. — It used to be so final: flush the toilet, and
waste be gone.
But on Nov. 30, for millions of people here in Orange County, pulling
the lever will be the start of a long, intense process to purify the
sewage into drinking water — after a hard scrubbing with filters,
screens, chemicals and ultraviolet light and the passage of time
On that Friday, the Orange County Water District will turn on what
industry experts say is the world’s largest plant devoted to purifying
sewer water to increase drinking water supplies. They and others hope
it serves as a model for authorities worldwide facing persistent
drought, predicted water shortages and projected growth.
The process, called by proponents “indirect potable water reuse” and
“toilet to tap” by the wary, is getting a close look in several cities.
The San Diego City Council approved a pilot plan in October to bolster
a drinking water reservoir with recycled sewer water. The mayor vetoed
the proposal as costly and unlikely to win public acceptance, but the
Council will consider overriding it in early December.
Water officials in the San Jose area announced a study of the issue in
September, water managers in South Florida approved a plan in November
calling for abundant use of recycled wastewater in the coming years in
part to help restock drinking water supplies, and planners in Texas are
giving it serious consideration.
“These types of projects you will see springing up all over the place
where there are severe water shortages,” said Michael R. Markus, the
general manager of the Orange County district, whose plant, which will
process 70 million gallons a day, has already been visited by water
managers from across the globe.
The finished product, which district managers say exceeds drinking
water standards, will not flow directly into kitchen and bathroom taps;
state regulations forbid that.
Instead it will be injected underground, with half of it helping to
form a barrier against seawater intruding on groundwater sources and
the other half gradually filtering into aquifers that supply 2.3
million people, about three-quarters of the county. The recycling
project will produce much more potable water and at a higher quality
than did the mid-1970s-era plant it replaces.
The Groundwater Replenishment System, as the $481 million plant here is
known, is a labyrinth of tubing and tanks that sucks in treated sewer
water the color of dark beer from a sanitation plant next door, and
first runs it through microfilters to remove solids. The water then
undergoes reverse osmosis, forcing it through thin, porous membranes at
high pressure, before it is further cleansed with peroxide and
ultraviolet light to break down any remaining pharmaceuticals and
The result, Mr. Markus said, “is as pure as distilled water” and about
the same cost as buying water from wholesalers.
Recycled water, also called reclaimed or gray water, has been used for
decades in agriculture, landscaping and by industrial plants.
And for years, treated sewage, known as effluent, has been discharged
into oceans and rivers, including the Mississippi and the Colorado,
which supply drinking water for millions.
But only about a dozen water agencies in the United States, and several
more abroad, recycle treated sewage to replenish drinking water
supplies, though none here steer the water directly into household
taps. They typically spray or inject the water into the ground and
allow it to percolate down to aquifers.
Namibia’s capital, Windhoek, among the most arid places in Africa, is
believed to be the only place in the world that practices “direct
potable reuse” on a large-scale, with recycled water going directly
into the tap water distribution system, said James Crook, a water
industry consultant who has studied the issue.
The projects are costly and often face health concerns from opponents.
Such was the case on Nov. 6 in Tucson, where a wide-ranging ballot
measure that would have barred the city from using purified water in
drinking water supplies failed overwhelmingly. The water department
there said it had no such plans but the idea has been discussed in the
John Kromko, a former Arizona state legislator who advocated for the
prohibition, said he was skeptical about claims that the recycling
process cleanses all contaminants from the water and he suggested that
Tucson limit growth rather than find new ways to feed it.
“We really don’t know how safe it is,” he said. “And if we controlled
growth we would never have to worry about drinking it.”
Mayor Jerry Sanders of San Diego, in vetoing the City Council plan
there, said it “is not a silver bullet for the region’s water needs”
and the public has never taken to the idea in the 15 years it has been
discussed off and on.
Although originally estimated at $10 million for the pilot study in San
Diego, water department officials said the figure would be refined, and
the total cost of the project might be hundreds of millions of dollars.
Although the Council wants to offset the cost with government grants
and other sources, Mr. Sanders predicted it would add to already
escalating water bills.
“It is one of the most expensive kinds of water you can create,” said
Fred Sainz, a spokesman for the mayor. “It is a large investment for a
very small return.”
San Diego, which imports about 85 percent of its water because of a
lack of aquifers, asked residents this year to curtail water use.
Here in Orange County, the project, a collaboration between the water
and sanitation districts, has not faced serious opposition, in part
because of a public awareness and marketing campaign.
Early on, officials secured the backing of environmental groups,
elected leaders and civic groups, helped in part by the fact the
project eliminated the need for the sanitation district to build a new
pipe spewing effluent into the ocean.
Orange County began purifying sewer water in 1976 with its Water
Factory 21, which dispensed the cleansed water into the ground to
protect groundwater from encroaching seawater.
That plant has been replaced by the new one, with more advanced
technology, and is intended to cope with not only current water needs
but also expectations that the county’s population will grow by 500,000
Still, said Stephen Coonan, a water industry consultant in Texas, such
projects proceed slowly.
“Nobody is jumping out to do it,” he said. “They want to make sure the
science is where it should be. I think the public is accepting we are
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