Tracking Wastewater's Path to Wells and Groundwater

Tracking Wastewater's Path to Wells and Groundwater

Research technician Susan Brown prepares the instrument for the analysis of artificial sweetener concentrations. (Photo By Pam Collins)

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Although people often “flush it and forget it” when it comes to wastewater, it’s important to track it to ensure it doesn’t end up in unwanted places. That’s why a group of Canadian scientists is pursuing an unlikely solution to trace where wastewater ends up.

What’s something found in all wastewater that will allow us to account for all of it? The answer, of all things, is artificial sweeteners. These have several advantages over other compounds sometimes used to track wastewater in the environment, according to the researchers.

“They are very specific to wastewater and have very few other possible sources in the environment,” says John Spoelstra, a research scientist with Environment and Climate Change Canada. “Their concentrations are often much higher than other wastewater markers and they don’t break down as quickly. This makes them easier to detect. Lastly, they are always present in wastewater. We have never found a wastewater sample that didn’t have these sweeteners present.”

Researchers looked at water from two sources in rural areas near Alliston, Ontario. The first was domestic water wells. They also considered groundwater seeps, or springs. Using the artificial sweeteners as a flag, they tested to see if septic system water ended up in those sources.

Overall, about 30 percent of the wells and springs contained one or more of the four sweeteners they searched for. Furthermore, they found 3.4 to 13.6 percent of the domestic wells had 1 percent or more of their water coming from the output of a septic system. This finding for seeps was 2 to 4.7 percent. This showed the groundwater contained water from a septic system.

“Although these sweeteners in groundwater themselves may not be a human health concern, the fact that they are there means there is also wastewater, which may contain other chemicals or bacteria of concern,” Spoelstra says. “Groundwater often gets to streams and lakes. Therefore the contamination of groundwater can also affect surface water quality. We currently don’t know the effects of artificial sweeteners on most organisms in the water.”

The researchers add that they didn’t test for bacteria and that these artificial sweeteners are considered safe to eat by the Canadian government. In the area of the study, their results also show the septic systems are not the main source of pollutants such as nitrates, which can also be found in local groundwater.

The sweeteners are found in wastewater from septic systems in rural areas as well as treated wastewater in urban areas because artificial sweeteners are difficult to remove in the treatment process, according to the researchers.

“Regular inspection and maintenance of septic systems and groundwater wells should be done to identify and fix possible problems,” says Spoelstra. “Homeowners should also have their raw well water tested for bacteria at least once per year.”

Read more about this research in the Journal of Environmental Quality. Environment and Climate Change Canada, the Ontario Ministry of Agriculture Food and Rural Affairs, and the Natural Sciences and Engineering Research Council funded this research.

Source: American Society of Agronomy


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