From wastewater to de-icer

You may have made a brine for your Thanksgiving turkey, but what about deicing your driveway?
The Glencoe City Council heard a proposal by Karen Cavett, of Short Elliot and Hendrickson (SEH), to turn the brine from the city’s wastewater into a solution to de-ice streets and help with dust control for gravel alleys.
The Minnesota Pollution Control Agency (MPCA) has set a standard for how much chloride can be in wastewater. Preliminary reports indicate that Glencoe’s rates of chloride in the wastewater exceed the 234 milligrams per liter standard.
The city of Glencoe treats the water with chloride to soften the hard water before it comes into the homes within the city.
The result is a brine, or a saltwater solution, that comes back through the sanitary sewer system into the wastewater treatment facility.
The levels at which the city softens the water are not believed to be the cause of the high levels in the wastewater, but rather the excess of water softeners in residents’ homes.
The first step will be to provide information to residents to educate them on the use of in-home water softners in an effort to reduce additional water softening within the city.
One option is to remove chlorides from the flow at  the waste water treatment facility. This would involve pre-treating the water with a micro-filtration system followed by a reverse osmosis filtering. This in turn would require additional treatment.
While this option is effective, it is also very expensive.
A more feasible option would be to install a filtration system that would collect the brine to be reused for other purposes.

For more,  see the Aug. 20 print edition of The Chronicle.