The use of pelletized, stabilized fly ash will beinvestigated as a substrate to enhance phosphorus (P) removal fromwastewater effluents in subsurface flow (SF) emergent plant-basedwetlands. The following experiments are being conducted in PhaseI to demonstrate the feasibility of using fly ash pellets as asubstrate in constructed wetlands for removing P: (1) Pabsorption/desorption isotherms for two sizes of each of twotypes of stabilized fly ash pellets; (2) screening of threeemergent macrophyte species rooted in two types of stabilized flyash for relative toxicity or inhibitory effects on growth,morphology, and foliage-to-rhizosphere oxygen transport; (3)greenhouse study of P removal from a continuous flow of municipalsewage effluent using SF woodland microcosms containing onemacrophyte species rooted in stabilized fly ash pellets; (4)potential leaching of boron, fluorine, arsenic, selenium, cooper,chromium, nickel, and molybdenum from stabilized fly ash pelletsfrom the SF woodland microcosms during nine weeks of exposure tosewage effluent; (5) hydraulic conductivity of the SF woodlandfly ash substrate before and after nine weeks of inundation; and(6) P and trace element uptake by root, rhizome, and shootportions of the emergent macrophytes cultured in the SF woodlandmicrocosms.Anticipated Results/Potential Commercial Applications as described by the awardee:S treatment wetlands with stabilized coal fly ashpellets as the substrate may prove to be cost-effective systems forremoving P from wastewaters prior to discharge. Design,construction, and operation of S woodland systems for use bymunicipalities, industries, and agriculture for treating effluentwastewater streams, process waters, and stormwater runoff arepromising commercial applications.
