Wetlands

Written - July 25, 2007

There has been a spotlight in Canada on treating drinking water for biological hazards, but less capacity to treat chemical ones. Though monitored (mostly), it is often too expensive to eliminate chemical pollutants from drinking water. The result: our water has become a brew of chemicals and toxins.

In 2004 Environment Canada was alarmed to find detectable levels of anti-depressants, pain killers and hormones in drinking water from Southern Ontario. It was found that the levels of these chemicals increased when water treatment plants were located downstream from sewage treatment plants.

Pesticide contamination has been documented in Ontario’s water since the 1970’s. In addition, industrial chemicals and metals are monitored routinely in drinking water. Although these chemicals do not pose an immediate hazard, chronic exposure effects are not well understood. Further, few studies have investigated the combined effects of toxins; each one is usually studied in isolation.

For metals and other inorganic compounds, removal options are expensive and often require chemical treatment to remove chemicals. Therefore little is done to eliminate these toxins as long as they are below regulated levels.

A major problem with treating drinking water for different pollutants is that each toxin has properties that require different treatments. For example, organic chemicals like pesticides can be removed with carbon filtration. However, chlorine is also removed by carbon filtration and carbon residue in water could inhibit the effectiveness of chlorine.

Moreover, it has come to light that treatment of water with chlorine presents hazards. The by-products of chlorine can be quite toxic to human health. However, the benefits of chlorine in treating biological pathogens support its use. Yet not all is doom and gloom, China has put a new twist on a reliable water treatment system.

In Shanghia, fifteen square kilometres of suburbs are being set aside to be restored as wetlands to help treat the city’s water. Wetlands are the most effective filters for removing any type of chemical from water, and the cheapest… all they require is land.

This is promising news for conservationists. Over two-thirds of Ontario’s wetlands have been lost to urban and rural development. Perhaps as the quality of water becomes paramount, Ontario can begin to look at wetland restoration as well. Sometimes the best technology is nature.