Graduate student researches new use for wetland model
Published August 23, 2012
Twice a week, graduate student Alex Stalboerger parks on the edge of a dirt road near Embden, N.D. He straps on his waders and carries a cooler through a field to the treatment wetland he built last summer.
The cooler isn’t for refreshments. It’s to keep water samples cool until he can test them in the lab at NDSU.
The wetland is designed to treat water for minerals that are common in North Dakota soil and in agricultural run-off. In high concentrations, the minerals can make humans sick and can make fish die. The water samples show how well the wetland is doing its job.
Used widely in Europe and by some U.S. industries, the treatment wetland model has not been used much by U.S. farmers. Stalboerger, a master’s student in environmental and conservation sciences, aims to change that.
Wetlands and water quality
Wetlands are important because they improve water quality, provide fish and wildlife habitats, store floodwater and maintain surface water flow during dry periods.
Since the 1600s, however, more than half of U.S. wetlands have been drained for other uses, according to the U.S. Environmental Protection Agency. To protect against further losses, the Clean Water Act requires compensatory mitigation if a wetland is lost to some other use, such as agriculture.
The treatment wetland will provide a new method to help North Dakota farmers to meet water quality regulations in a cost-effective way. “We are developing a wetland that a farmer can build onsite as part of the mitigation process,” he says. “But we are designing it in a way where it pays for itself. The costs of water treatment alone will pay for the wetland within a year if they were to be monetized.”
Designed for North Dakota
Treatment wetlands, Stalboerger explains, can be natural or constructed but are always modified to treat specific chemicals, compounds or minerals. The wetland he built is based on research conducted in Ireland by Marinus Otte, professor of biological sciences at NDSU, and one of Stalboerger’s co-advisers.
“The problems in Ireland were excess sulfate in mine drainage water at a major zinc mine and excess phosphate in waste water from a dairy processing plant,” Otte says. “Wetlands are effective in removing both from water and it was one of the areas of research we pursued. In both cases, as here in North Dakota, we constructed wetlands, which were successful in lowering the levels of both pollutants.”
Stalboerger spent summer 2011 constructing the wetland adapted for North Dakota soil and environment. It is made from 13 tons of cinder block as well as soil and decomposed manure, willows, broadleaf cattail plants, pvc pipe and a 200-gallon basin. This spring he started collecting data to see how the wetland is affecting water quality.
At the wetland, he picks his way through long grass and plants to a basin where drainage from the field collects. He submerges a plastic bottle in the water. Samples from that location give him baseline data about sulfate and phosphate levels before the water goes through the treatment cells.
The first treatment cell is a sediment pond. The mucky mixture of soil and decomposed manure removes sulfates. Common in North Dakota soil, high levels of sulfates cause digestive problems, such as diarrhea, in humans.
The anaerobic process that removes sulfates, however, increases phosphates, Stalboerger explained. Excess phosphates cause algae to grow out of control. And excess algae deplete oxygen in the water, causing fish to die.
The second treatment cell, where the second sample comes from, has deeper water where broadleaf cattails and willows oxygenate the water. The oxygen immobilizes the phosphates, preventing them from entering the creek that flows into the river.
Stalboerger said the willows have potential as a biofuel that can be burned for heat or electricity generation. A landowner could either use the energy or sell the biofuel to generate income.
He takes the last two samples from a creek and finally the river.
Ultimately, the goal of the research project is to effectively treat water for sulfates and phosphates as well as build the wetland at a low initial cost to the landowner in a way where it pays for itself and has the potential to generate income. “All of these have to be supported through actual data, which is where I come in,” he said.
The wetland research is funded by grants from the U.S. Department of Agriculture, the Environmental Protection Agency and North Dakota Water Resources Research Institute.
When Stalboerger graduates, he plans to put his knowledge to work for an environmental consulting firm, a government agency or a private company that specializes in natural water treatment systems.
Other NDSU students will continue to use the treatment wetland to conduct field research.
Stalboerger’s other co-adviser is Donna Jacob, research assistant professor of biological sciences.