AN EVALUATION OF TWO PELLETIZED COAL FLY ASHES AS SUBSTRATES FOR SUBSURFACE FLOW WETLAND WASTEWATER TREATMENT SYSTEMS

THE USE OF PELLETIZED, STABILIZED FLY ASH WILL BE INVESTIGATED AS A SUBSTRATE TO ENHANCE PHOSPHORUS (P) REMOVAL FROM WAS5TEWATER EFFLUENTS IN SUBSURFACE FLOW (SF) EMERGENT PLANT-BASED WETLANDS. THE FOLLOWING EXPERIMENTS ARE BEING CONDUCTED IN PHASE I TO DEMONSTRATE THE FEASIBILITY OF USING FLY ASH PELLETS AS A SUBSTRATE IN CONSTRUCTED WETLANDS FOR REMOVING P: (1)P ADSORPTION/DESORPTION ISOTHERMS FOR TWO SIZES OF EACH OF TWO TYPES OF STABILIZED FLY ASH PELLETS; (2) SCREENING OF THREE EMERGENT MACROPHYTE SPECIES ROOTED IN TWO TYPES OF STABILIZED FLY ASH 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 MUNICIPAL SEWAGE EFFLUENT USING SF WETLAND MICROCOSMS CONTAINING ONE MACROPHYTE SPECIESROOTED IN STABILIZED FLY ASH PELLETS; (4) POTENTIAL LEACHING OF BORON, FLUORINE, ARSENIC, SELENIUM, COOPER, CHROMIUM, NICKEL, AND MOLYBDENUM FROM STABILIZED FLY ASH PELLETS FROM THE SF WETLAND MICROCOSMS DURING NINE WEEKS OF EXPOSURE TO SEWAGE EFFLUENT; (5) HYDRAULIC CONDUCTIVITYOF THE SF WETLAND FLY ASH SUBSTRATE BEFORE AND AFTER NINE WEEKS OF INUNDATION; AND (6) P AND TRACE ELEMENT UPTAKE BY ROOT, RHIZOME, AND SHOOT PORTIONS OF THE EMERGENT MACROPHYTES CULTURED IN THE SF WETLAND MICROCOSMS.