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DiPietro, Thomas J.

Plant and Soil Science

2005

MS

Greenhouse experiments were conducted in laboratory-scale, subsurface constructed wetland cells to investigate the effects that aeration and chemical oxygen demand (COD) have on wetland plants and examine microbial community diversity. Species tested were Scirpus atrovirens Willd., Iris versicolor L. and Schoenoplectus fluviatilis (Torr.) M. T. Strong. Measurements of plant biomass and root architecture, including length, surface area, diameter and volume, were taken to characterize plant responses to dairy wastewater and aeration. Water samples were also analyzed to examine the effect that plants and aeration have on wastewater treatment. Supplemental aeration had a varied effect on root growth dependent upon plant species, but a consistent positive influence on reduction of COD. Root growth declined sharply when higher COD wastewater was added to research cells regardless of species. Aeration did not significantly impact plant biomass, however, in some cases increased COD of wastewater significantly reduced plant dry weights. Over a thirty-day period, all species increased root surface area by more than 270 % in cells containing low COD and no aeration. In cells containing high COD and aeration root surface area increased by less than 76% in all species. T -RFLP analysis has shown that twice as many microbial ribotypes are present in cells containing S. fluviatilis as compared to those with synthetic roots and control cells. Fifty-eight microbial ribotypes were found on S. fluviatilis roots, compared to only 21 on synthetic roots. Of these ribotypes, 17 were found on both synthetic and S. fluviatilis roots.