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Pharmaceuticals and Personal Care Products in the Canadian Environment: Research and Policy Directions

5.1 Wastewater Treatment

Although WWTPs are designed to remove solids, nutrients, and biodegradable organic matter, through their normal operation, these plants will also remove many types of PPCPs. Published research indicates that the most common sequence of treatment - primary settling followed by biological treatment, secondary clarification and disinfection - can remove over 90% of endocrine disrupting compounds from wastewater through degradation and/or partitioning (WERF, 2005).

Sewers are generally viewed as the dominant disposal path for PPCPs consumed by households, hospitals and industry. With thousands of different PPCPs in the market for human use in Canada, centralized WWTPs represent a major potential PPCP point source to the aquatic environment, and a major opportunity for centralized removal processes.

This, in combination with increased therapeutic drug use - Canadian drug expenditures grew by an average annual rate of 12.2% between 1985 to 1992 (CIHI, 2004) - rationalizes, to a large extent, the considerable research effort underway to explore PPCP removal mechanisms at centralized WWTPs.

In Europe for example, the EU project POSEIDON, funded between 2001 and 2004 as a major research priority of and supported by the EU’s 5th Framework Programme for Research, was aimed at assessing the optimal treatment technologies for both wastewater treatment and drinking water treatment processes. In the U.S., the Water Environment Research Foundation (WERF), American Water and Wastewater Association’s Research Foundation (AWWARF), WaterReuse Foundation and a range of research institutes and urban water agencies are developing a growing compendium of research results on the removal of PPCPs through wastewater treatment processes. In Canada, Environment Canada, the Ontario Ministry of Environment and several academics are engaged in PPCP and wastewater treatment research.

Summarizing research results in this area is not simple. The reader is directed to section 3.3 and 7.0 for additional information. Individual PPCPs have distinct chemical and physical properties that suggest potentially different mechanisms and locations for removal/reduction in a WWTP. Reduction measurements are further complicated by biological transformations, the effects of mixtures, hydraulic and temperature variations, analytical limitations and the combination of treatment processes in a WWTP. Advanced treatment such as ozonation, activated carbon, and tight membrane filtration are receiving considerable attention, while research into a better understanding of removal in conventional treatment (primary, secondary and tertiary) remains active. Understanding removal in conventional treatment is particularly important in the Waterloo sewage treatment plant | Photo: Shirley Anne SmythCanadian context since the additional cost of advanced treatment tends to be incurred only where wastewater reuse is necessary, such as in parts of Europe and the southern U.S., and the need for wastewater reuse in Canada is minimal at present. Although the current lack of evidence on widespread environmental effects makes it premature to justify increased operating and capital costs, most researchers conclude that centralized municipal wastewater treatment has the potential to make a significant contribution to reducing the load of PPCPs to the aquatic environment. If and when toxicological effects evidence is sufficient to warrant additional treatment, it is practicable that abatement design will not be tailored to an individual compound but based rather on overall capacity to remove trace contaminants. Until then, research in this area remains of fundamental importance.

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