Richard P. Reaves, Paul J. DuBowy, Don D. Jones, Alan L. Sutton 1
Purdue University is involved in an on-going project to determine the efficacy of utilizing constructed wetlands for the treatment of swine lagoon wastewater. A constructed wetland with 16 parallel cells was built at the Purdue University Animal Science Swine Research Center. Tests were conducted for three hydraulic loading rates and two operating depths. Three replicates were conducted for each combination tested. Cell influent and effluent were analyzed for BOD, fecal coliforms, total nitrogen, total phosphorus, and TSS. Cell vegetation was measured for composition, percent cover, and plant vigor. Comparisons of treatment efficiencies and vegetation performance were conducted to determine the best system operating parameters for a constructed wetland in northern Indiana. First year data indicated an operating depth of 15 cm coupled with a 14 day hydraulic residence time provides better water treatment in the climate of the upper midwest. Greater depths adversely affected plants while shorter residence times reduced treatment. For systems with very high lagoon ammonia-nitrogen levels, an initial unvegetated zone may provide a means of reducing ammonia to a level more easily tolerated by wetland plants. This could allow for better plant growth and enhanced overall system performance.
