Courtesy of Conservation Maven comes news of a constructed wetland in the Netherlands that removes pollutants from a river, helps control floods, and produces biomass to generate energy. Sounds like my kind of wetland.
I didn’t read the study itself, just the review, but what the researchers did was plant reeds in a field, divert a stream through it, and then measure the eutrophication of the water (the extent to the water has become “enriched” by nutrients, usually from farm field runoff) and the amount of biomass produced.
Eutrophication was measured before and after the diversion, and a comparison showed that more than 40 of the nitrogen and phosphorus in the water had been absorbed by the reeds. With regard to the biomass produced, the article has this to say:
The constructed wetland was also highly productive. After only one year of growth post-establishment 221 g/m2 biomass had accumulated and after two years, the amount increased to 903 g/m2. These findings show that constructed wetlands can provide a useful tool to prevent eutrophication in surface waters while generating a potentially valuable crop for farmers.
“While generating a potentially valuable crop for farmers…” Just think what farmers in the Mississippi River system could do with this. That’s the river system that carries such a nutrient load as to produce a huge dead zone in the Gulf of Mexico each year. Wouldn’t it be great if we could reduce or even get rid of the dead zone? Wouldn’t it be great if farmers could also have a way to generate energy from their own lands or to sell the energy or biomass to others?
Certainly in the United States, most farmers would be thrilled to have an extra source of income. And if they could negotiate a deal with a company to make the wetland and then pay that company out of the proceeds from the biomass, farmers wouldn’t have to take on more debt to help rivers.
Source: “Constructing Wetlands to Sanitize Rivers and Produce Green Energy,” Conservation Maven, March 30, 2010