Saturday, 15 July 2006

Feasibility of Using Ornamental Plants to Remove Nutrients From Treated Municipal Wastewater in Constructed Wetlands.

Zhenhua Zhang1, Zed Rengel1, and Kathy Meney2. (1) Soil Science and Plant Nutrition, The Univ of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009,, Perth, Australia, (2) Syrinx Environmental Pty Ltd, 12 Monger St., Perth, Australia

A glasshouse experiment was conducted to test the feasibility of using ornamental wetland species in constructed wetlands to remove nutrients (nitrogen and phosphorus) from secondary treated municipal wastewater and the potential of different species in mixculture. Ten emergent wetland plants, including six ornamental species: Canna indica, Lythrum sp., Alocasia macrorrhiza, Zantedeschia aethiopicia, Iris louisiana, Zantedeschia sp., and four native rush species: Carex tereticaulis, Baumea juncea, Baumea articulata and Schoenoplectus validus were planted in microcosm and fed a synthetic wastewater solution in concentrations similar to the secondary treated municipal wastewater. Allocation of organic matter to above- and below-ground growth and nutrient uptake were compared for all of the tested species. After 98 days growth, significant differences (P < 0.05) in both above- and below-ground biomass were observed, with mean total biomass ranged between 208 and 806 g m-2. The highest above-ground biomass was reached by Alocasia macrorrhiza. Maximum below-ground biomass was recorded for Lythrum sp.. Significant differences among species in accumulations of N (P < 0.05) and P (P < 0.05) were detected in both above- and below-ground tissues. The highest accumulations of N and P in above-ground were Alocasia macrorrhiza, due to its relatively large biomass. In addition, significant differences of pH (P< 0.05) and dissolved oxygen (DO) (P < 0.05) were found in the effluents. The highest pH was recorded in the effluent from microcosm containing Schoenoplectus validus and the lowest in the effluent from microcosm with Canna indica. The highest DO was also found in the effluent from microcosm containing Canna indica. Nonetheless, It was suggested that Schoenoplectus validus and Canna indica might be two suitable candidate species to test in mixed culture in the constructed wetland for more efficient use and removal of both N and P from the wastewater.

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