The 2010 ASHS Annual Conference

Determining the potential for Penstemon barbaris and Canna glauca in horizontal sub-surface flow wastewater treatments

Constructed wetlands offer communities, companies and homeowners aesthetically pleasing and effective treatment possibilities for their wastewater. Plant choices play a large role in the success of a constructed wetland, offering both physical presence and toxin stabilization. The University of Maine chapter of Engineers Without Borders is working on designing a horizontal sub-surface flow wastewater treatment system in Dulce Vivir, Honduras. The plants chosen needed to be native to Central America, and tolerant of both wet and dry conditions, high porosity media, and wastewater exposure. Canna glauca and Penstemon barbaris were grown in closed systems with effluent from the Orono, Maine Wastewater Treatment Plant to simulate the conditions of a constructed wastewater wetland with one of the following treatments: 0% effluent, 50 % effluent, and 100% effluent. Salinity (measured as electrical conductivity) increased 61.9% from 0.39 mS/cm to 0.63 mS/cm in 0% to 100% effluent respectively for P. barbaris, and increased 52.9% from 0.37 mS/cm to 0.70 mS/cm in 0% to 100% effluent respectively for C. glauca. Despite the changes in salinity, all of the plants survived and grew equally well as measured by height, width and root length. The project demonstrated that C. glauca and P. barbaris are good candidates for constructed wetlands through their survival and performance in the experiment.