title: Performance of two macrophyte species in experimental wetlands receiving variable loads of anaerobically treated municipal wastewater.
abstract: Two highly productive emergent macrophytes, Zizaniopsis bonariensis and Typha subulata were established in experimental subsurface flow, sand-based wetlands receiving anaerobically treated municipal wastewater. The hydraulic loading rate was tested in two levels, sequentially, 6.8 cm x d(-1) and 13.6 cm x d(-1), for 70 days each. In the 13.6 cm x d(-1)-loading treatment, among all monitored variables only COD, PO4-Total-P, and Turbidity were removed more efficiently by the planted beds in comparison to unplanted sand beds (P<0.001). When the 6.7 cm x d(-1)-loading rate was applied no significant improvement in removal was found comparing macrophyte beds to unplanted sand beds, except for PO4-P. T. subulata beds were significantly more efficient than Zbonariensis beds for most of the variables. The highest significant differences (P< 0.001) were related to the main effect of the factor hydraulic loading rate, with decreased removal for increased load when considering the variables Total Coliforms (99.4% to 87.7%), Fecal Coliforms (100% to 89.7%). NH3-N (95.8% to 55.2%), NO3(-)-N (-54% to -396%), Total-N (90.4% to 59.6%), and TSS (86.1% to 46.1%). The performance similarity of planted and unplanted wetland beds in the lower loading condition, except for PO4-P, indicates that plants may not be needed under low loading. However aquatic macrophytes improved wetland efficiency under high loading.
authors.affiliation: Instituto de Pesquisas Hidráulicas, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. dmm@iph.ufrgs.br
authors.forename: D M
authors.initials: DM
authors.lastname: da Motta Marques
authors.forename: G R
authors.initials: GR
authors.lastname: Leite
authors.forename: S G
authors.initials: SG
authors.lastname: Giovannini
mesh_terms: D001421:Bacteria, Anaerobic; D005374:Filtration; D009584:Nitrogen / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D006109:Poaceae / Q000502:physiology*; D012822:Silicon Dioxide; D014865:Waste Disposal, Fluid / Q000379:methods*; D014872:Water Movements; D014876:Water Pollution / Q000517:prevention & control
chemical_list: D010758:Phosphorus; D012822:Silicon Dioxide; D009584:Nitrogen