[Southern_AZ_MWS] From Sewage, Added Water for Drinking
Betsy.Frederick at seacon.com
Wed Nov 28 11:15:09 MST 2007
The issues are always evolving (and I'm sure there are some others on
the list with significantly better credentials to comment) but in part
there is no question in my mind that this is as much socio/political as
it is about science. The fact is that new contaminants are entering our
water resources through a variety of means all the time, not the least
being pharmaceuticals, much of which is not treated adequately by the
traditional methods of wastewater treatment that most of the country
uses now. On the other hand, it is also true that huge portions of the
country are regularly using "toilet to tap" without so much as a second
thought because it just doesn't occur to them that this is their current
condition. They mentioned something similar in the article you attached
below, but for instance, the Merrimack River, the watershed of which
encompasses much of Southern New Hampshire and portions of northern
Massachusetts, is both the receiving water body for multiple wastewater
treatment plant discharges as well as the drinking water supply for
hundreds of thousands of people. What gets discharged upstream is
consumed downstream. About a mile downstream in fact. That's a fact
now, not sometime in the future.
I've always been surprised that people who have been drinking water from
their wells situated not too far from their septic system (that's if it
isn't just a cesspit) for a lifetime see this as such a newfangled idea.
I haven't really kept up on the technology but I know in the past many
of the problems associated with injection well technology have revolved
around fairly mundane "mechanical" issues - not the science associated
with natural attenuation of contaminants or the natural filtering
capacity of soils. Maintaining well screens adequately in the face of
organic growth on the screens, etc., has impacted pumping and operating
efficiencies and therefore costs. By the way, I laughed when I read the
description of the water in the system below, because I for one am not
interested in drinking "distilled" water. It's not good for you, ya
From: gila_stacruz_mws-bounces at CALS.arizona.edu
[mailto:gila_stacruz_mws-bounces at CALS.arizona.edu] On Behalf Of Cathy
Sent: Tuesday, November 27, 2007 10:17 AM
To: MWS List
Subject: [Southern_AZ_MWS] From Sewage, Added Water for Drinking
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
"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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