[Pharmwaste] Removing nutrients and pharmaceuticals short article

Tenace, Laurie Laurie.Tenace at dep.state.fl.us
Wed Feb 13 15:19:05 EST 2008


http://pubs.acs.org/subscribe/journals/esthag/41/i03/html/020107news5.html


Removing nutrients and pharmaceuticals
Traditional sewage treatment plants are seen as a primary source of trace
concentrations of household and industrial chemicals in rivers and streams.
That's hardly a surprise, because conventional treatment plants weren't
designed to remove drugs, cosmetics, soaps, deodorants, insect repellants,
and other exotic contaminants from effluent discharged into waterways.

But tightening up current methods on nutrient pollution may be all that's
needed. Research now shows that actions taken at facilities to reduce
nutrients, such as nitrogen and phosphorus, are also removing a good portion
of pharmaceuticals and personal care products (PPCPs).

In one of the first U.S. studies to look at how longer solids retention times
(SRTs) affect PPCP removal, researchers from MWH, an environmental
engineering consulting firm, characterized the passage of various PPCPs
through six treatment plants of varying sizes in California and New Mexico.

The SRT is how long a facility holds on to sludge to allow processing by
microbes. The researchers found that SRTs of 5-15 days were sufficient to
remove many of the 20 compounds they were targeting that are commonly
detected in wastewaters and waterways.


Still, some resisted biodegradation. The most problematic compounds were
fragrances, such as musk ketone and galaxolide, and trichloroethyl phosphate,
a flame retardant, says Joan Oppenheimer, an environmental scientist with
MWH. Oppenheimer presented her findings in October at the Water Environment
Federation's conference in Dallas, Texas.

The new research validates data from Europe, where similar studies have been
conducted at the bench scale or at small full-scale treatment plants. The MWH
study, by contrast, sampled large full-scale plants, which operate in major
metropolitan areas, with capacities ranging from 5 to greater than 300
million gallons per day. All were conventional activated-sludge plants, the
industry standard, operating at SRTs ranging between 0.5 and 30 days.

Oppenheimer and her colleagues also looked at PPCP removal through subsequent
filters and disinfectants as well as newer treatment processes, such as
membrane bioreactors, but for the most part they found no additional removal.
Reverse osmosis after regular filtration, however, did reduce all of the
compounds to below detection limits.

What's encouraging about these findings is that a push by the U.S. EPA and
states "to go to increased nutrient reduction also helps this problem" of
PPCPs, Oppenheimer says. No federal standards exist on nutrients, just
criteria guidelines that EPA issued in 2001-2002. State regulatory agencies
are supposed to either implement EPA's criteria or develop their own, but
progress has been very slow.

The significance of the MWH study is that "it was done in the U.S. with our
style of operation and our contaminants and that it confirms some of the same
results that have been seen in Europe," says Rhodes Trussell, head of
Trussell Technologies, Inc.

Many sewage treatment plants in the U.S. commonly operate with very low SRTs,
Trussell notes. "If we make a decision as a nation that we want to maximize
removal of these compounds, and there are a number of them, the science is
showing that longer SRTs will be necessary," he points out.

Laurie J. Tenace
Environmental Specialist
Florida Department of Environmental Protection
2600 Blair Stone Road, MS 4555
Tallahassee, Florida 32399-2400
PH: (850) 245-8759
FAX: (850) 245-8811
Laurie.Tenace at dep.state.fl.us 

Mercury web pages:
http://www.dep.state.fl.us/waste/categories/mercury/default.htm

Unwanted Medications web pages:
http://www.dep.state.fl.us/waste/categories/medications/default.htm




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