In the past few months, I have had a couple questions about the viability of constructed wetlands to treat septic tank effluent in cold climates. A little review is necessary before I answer the question. Our part of the wastewater industry uses constructed wetlands as an additional pre-treatment option. One way to think about this is as a media filter (just like a media, sand or peat filter). In the treatment train, it would follow the septic tank and be ahead of the final soil dispersal and treatment area.
There are three general types of constructed wetlands: open water, hydroponic
