Monday, May 13, 2013
Efforts to secure a long-term water supply in some drought-ridden areas could also make it harder for future pharmaceutical chemicals to make it into drinking water. According to a study published this year in Science of the Total Environment, chemicals new to the market or currently undergoing testing are more susceptible to a treatment process commonly used to make wastewater safe to drink, a method gaining in popularity as more areas are forced to make the most of the water they have.
The Achilles' heel of many future chemicals is their size. While examining approximately 2,000 new pharmaceutical compounds, researchers discovered a trend towards medicines derived from natural molecules like proteins. In fact, more than 60 percent of the chemicals currently in the early stages of FDA testing are biopharmaceuticals. It will be many years, even decades, before these medicines can be bought at local drugstores. But when they do, their large size will make it easier to filter them out of wastewater.
This will especially be the case if the filter is a reverse osmosis membrane, which is specifically designed to allow smaller molecules through while trapping those bigger than its pours. Models used in the study to predict chemical behavior suggest that reverse osmosis would remove over 98 percent of the 2,000 chemicals tested. And the chemicals that made it through would likely not persist in the environment.
Right now, reverse osmosis is commonly used in household drinking water purification systems and to desalinate sweater. But cities like San Diego, Phoenix, and Tampa have shown interest in using this same process to recycle and reuse wastewater after it leaves a conventional treatment plant.
Lim, S.J., Fox, P. 2013. Prediction of the potential fates of future pharmaceutical compounds in indirect potable reuse systems. Science of the Total Environment, 444:417-422.