[Pharmwaste] Nutrient removal also extracts pharmaceuticals

DeBiasi,Deborah dldebiasi at deq.virginia.gov
Tue Jan 9 14:11:30 EST 2007


This is encouraging!



Science News -December 27, 2006

Nutrient removal also extracts pharmaceuticals

Sewage treatment plants that operate with longer solids retention times
remove more pharmaceuticals and personal care products. 
 
Roger Stephenson, MWH
Sewage treatment plantTraditional 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 repellents, 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. "Even if we don't know what all
these compounds are, as we go to longer SRTs, we've got a more diverse
community of microorganisms, and we seem to be able to reduce more of
them." No federal standards exist on nutrients, just criteria guidelines
that EPA issued in 2001. 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. 

Rolf Halden, an assistant professor of environmental health sciences at
the Johns Hopkins Bloomberg School of Public Health, agrees. "This study
provides additional evidence for the notion that SRT is an important
operational parameter influencing PPCP removal during biological
wastewater treatment," he says. 

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. 

Treated wastewater is also the source water for indirect potable reuse
projects, Oppenheimer adds. Better understanding of the fate of these
compounds in treatment plants helps "us figure out what we can do about
conventional treatment processes to enhance the quality of this source,"
she says. -KRIS CHRISTEN 


Deborah L. DeBiasi
Email:   dldebiasi at deq.virginia.gov
WEB site address:  www.deq.virginia.gov
Virginia Department of Environmental Quality
Office of Water Permit Programs
Industrial Pretreatment/Toxics Management Program
Mail:          P.O. Box 1105, Richmond, VA  23218 (NEW!)
Location:  629 E. Main Street, Richmond, VA  23219
PH:         804-698-4028
FAX:      804-698-4032



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