Technology▼Solutions Keeping drugs out of drinking water
© 2002 American Chemical Society
regulator, bezafibrate, and a metabolite of the lipid regulator clofibrate, clofibric acid; and diclofenac, an arthritis drug. The paper is notable for evaluating the removal efficiency APPLIED RESEARCH DEPARTMENT OF MONTGOMERY WATSON HARZA
The first systematic investigation of how effectively drinking water treatment technologies remove pharmaceutical products has found that the technologies being used in Germany appear to do a good job, according to new ES&T research (Environ. Sci. Technol. 2002, 36, 3855–3863). However, the paper’s lead author, Thomas Ternes of Germany’s Institute for Water Research and Water Technology (ESWE), says that some of the technologies used elsewhere in the world—particularly in the United States—may be letting pharmaceuticals through. Although research shows that pharmaceutically active products are found in surface waters throughout the United States (Environ. Sci. Technol. 2002, 36, 1202–1211) and Europe, there is as yet very little information on how effectively different drinking water treatment technologies remove these pharmaceutical residues. Ternes’s work, which represents the most comprehensive assessment published to date, was funded in part by the European Union’s (EU’s) ongoing Poseidon program for assessing technologies for removing pharmaceuticals and personal care products in sewage and drinking water treatment facilities. The program is also aimed at evaluating the ability of advanced wastewater treatment technologies like membranes and source separation to reduce the volume of pharmaceuticals being discharged into EU waters. Ternes and his fellow researchers at ESWE and two other organizations associated with the German Technical and Scientific Association on Gas and Water (DVGW), the Technologiezentrum Wasser and the Institute for Water Research, investigated how effectively treatment technologies were able to eliminate five pharmaceutical products often found in German waters: two epilepsy medications, carbamazepine and primidone; one lipid
Ozone is one of the technologies that testing shows can remove pharmaceutical compounds from drinking water, although more research is needed on the byproducts it can generate.
of a number of popular technologies— flocculation, ozonation, granular activated carbon (GAC), bank filtration, and slow sand filtration—both in the laboratory and in waterworks treatment facilities. Both GAC and ozonation were very effective at removing carbamazepine and diclofenac at both laboratory and waterworks scales, Ternes found. Laboratory-scale ozonation treatments showed that 0.5 milligrams/liter (mg/L) of ozone reduced the two pharmaceuticals by more than 90%. Although GAC was very successful in removing bezafibrate during waterworks testing, laboratory-scale ozonation treatments with much higher concentrations of ozone (3.0 mg/L) were required to reduce it by 90%. The laboratory scale also showed that
3.0 mg/L of ozone cut primidone levels by nearly 90%. Although neither GAC nor ozonation at any concentration was fully successful with clofibric acid separately, the two in combination cut levels of the drug to below the limits of detection during waterworks testing. GAC is effective because carbon can bind a broad category of compounds, and many pharmaceuticals have components like benzene rings or amine groups that enhance their ability to be taken up by the activated carbon, Ternes explains. The powdered form of activated carbon can be even more effective, removing virtually every possible pharmaceutical and personal care product, adds Shane Snyder, the project manager for research and development at the Southern Nevada Water Authority. But he stresses that GAC—like all technologies—is only effective if used properly. Ozone’s effectiveness is tied to its ability to chemically attack the pharmaceutical molecules, Snyder says. For example, it can oxidize different kinds of functional aromatic bonds in pharmaceuticals, he says. Ternes adds that his research has shown ozone capable of easily oxidizing 90% of 51 different pharmaceuticals. It is particularly effective with compounds with amine groups and phenolic hydroxyl groups, he says. On the basis of the testing he has conducted thus far, Ternes concludes that contamination of German drinking water by the chemicals he investigated is “rather unlikely”, given that the waterworks treating surface water, which is most likely to contain pharmaceutical residues, use either ozonation or activated carbon, or perhaps both. He believes that other advanced techniques, such as membrane filtration and advanced oxidative processes using a combination of ozone and UV or ozone and hydrogen peroxide, should also remove pharmaceuticals. Most pharmaceutical products are not removed by conventional flocculation technology because their polar-
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APPLIED RESEARCH DEPARTMENT OF MONTGOMERY WATSON HARZA
ity makes them unlikely to adsorb to such as those that use coagulation believes that Ternes’s carbamazepine organic matter, he explains. and flocculation followed by filtration results are most relevant in the United The paper does not address the and disinfection with a chlorine prodStates; he notes that his studies of multitude of degradation products uct, cannot efficiently remove trace recharging groundwater have shown that can be produced by oxidative organic pollutants such as low levels that the compound can survive intact treatments such as ozone, points of pharmaceuticals and personal care after traveling 8–10 years through the out Christian Daughton, chief of the products, says Jörg Drewes, an assissubsurface. environmental chemistry branch tant professor in the Colorado School Because of the increasing popuof the U.S. EPA’s National Exposure of Mines’ Environmental Science and larity of groundwater recharging in Research Laboratory’s Environmental Engineering division. In such systems, places like the United States, all of the Sciences division. For example, re“it may be possible that these comscientists interviewed for this article cent research conducted by Roberto pounds add up to the contamination concurred that groundwater may beAndreozzi of the University of Naples of drinking water,” Ternes adds. come contaminated with pharmaceuin Italy (Water Res. 2002, 36, 2869– ticals. Ternes adds that the risk that 2877) shows that numerous pharmaceutical compounds metabolites can persist after carwill be found in groundwater bamazepine has been treated is “relatively high” for locawith ozonation, Daughton says. tions where surface water inTernes says that he is already trudes into the groundwater. investigating such oxidation Although the risk associatproducts—as well as other ed with consuming the low drinking water treatment techlevels of pharmaceuticals Testing demonstrates that activated carbon can remove “virtunologies, including membrane ally every possible pharmaceutical and personal care product” found in U.S. and European filtration—through the Poseidon waters is as yet unknown from drinking water if it is used properly. program. Between the Poseidon (Environ. Sci. Technol. 2002, 36, program and a project begun this year Most countries outside central 140A–145A), Ternes notes that any by the American Water Works Europe—including the United antibiotics that find their way into Association’s Research Foundation States—use either chlorine, chlosurface waters and other natural (AWWARF), virtually all treatment ramines, or ozone to disinfect drinkwater bodies could promote antibiottechnologies in current use are being ing water, Drewes says. To date, the ic resistance. tested, says Snyder, who is the AWWARF studies have shown that “The major concern associated AWWARF project’s principal investigachlorination can add another barrier with the presence of [pharmaceutitor. to pharmaceutically active comcally active compounds] in drinking The AWWARF project’s goal is to pounds, but it is not nearly as effecwater is not acute effects on human evaluate how well different drinking tive as ozone, Snyder says, stressing health (since environmental concenwater treatments remove 42 comthat the results are as yet unpubtrations are orders of magnitude pounds representative of the pharlished. He and his fellow researchers below the therapeutic dosages), but maceutical products found in U.S. haven’t yet tackled chloramines, but rather the manifestation of impercepwaters. It is notable for its goal of he doesn’t expect them to be as effectible effects that can accumulate over developing quantitative structure– tive as chorine. time to yield truly profound changes,” activity relationship (QSAR) computer Both ozonation and GAC are inDrewes says. “And the latter is exmodels that predict how pharmacreasingly popular in the United tremely difficult to determine.” ceuticals will respond to different States, but they are still only used by On the positive side, the new techtreatments based on their chemical a relatively small number of larger nologies that are likely to be put in structure. The study therefore indrinking water treatment facilities, place to reduce the probability of cludes a wide array of different types says Steve Via, a regulation engineer pharmaceuticals making their way of compounds—such as acidic, basic, at AWWA. According to a survey of into drinking water, such as activated large, and small molecules—chosen how U.S. facilities treat surface water carbon, could have the additional to represent the pharmaceuticals and by the U.S. EPA in 1997, the latest benefit of removing “all sorts of other personal care products that can be year for which figures are available, chemicals we don’t even know about found in the environment. 5.4% of U.S. facilities serving 50,000– at the present,” Daughton says. “The The AWWARF project will have 100,000 people used ozone and 7.7% analytical chemists have gotten way succeeded in its goal if “when we read used GAC. Of treatment providers for ahead of us,” in terms of their ability a paper in ES&T with the newest enover 100,000 people, 5.8% used ozone to devise new ways to detect chemidocrine disrupter of the month, we and 6.4% used GAC. cals that may be found in the envican go back to our data set . . . and Although the pharmaceutical comronment, he explains. Because see how these treatment processes pounds that Ternes studied have been environmental chemists regularly will remove [it],” says Snyder, who is reported in wastewater and surface discover new and unexpected comthe project’s principal investigator. water outside Germany, Drewes says pounds in the nation’s waters, he However, Snyder and his colleagues that clofibrate is no longer commonly predicts that greater use of advanced have not yet published any results. used as a lipid regulator in the United water treatment technologies could Although more study is clearly States, and studies by his lab and othrepresent a “much, much higher reneeded, Ternes’s findings hint that ers have found it only in some U.S. duction of overall risk” from such conventional water treatment plants, wastewater effluents. Drewes says he compounds. —KELLYN S. BETTS
