PHOSPHORUS REMOVAL IN AGRICULTURAL RUNOFF USING AN INTEGRATED WETLAND/CHEMICAL SYSTEM

A PROPOSED INTEGRATED WETLAND-CHEMICAL TREATMENT SYSTEM HAS THE POTENTIAL TO BE AN EFFECTIVE, ECONOMICAL, AND ENVIRONMENTALLY ACCEPTABLE TECHNIQUE FOR REMOVING PHOSPHORUS FROM AGRICULTURAL WASTEWATERS. THE PROPOSED SYSTEM CONSISTS OF A SUBMERSED MACROPHYTE POND (SMP) FOR SUSPENDED SOLIDS, DISSOLVED ORGANIC CARBON AND P REMOVAL, AS WELL AS ELEVATION OF WATER COLUMN PH LEVELS. EFFLUENT FROM THE SMP IS PROVIDED WITH ADDITIONAL PH ADJUSTMENTS AND FLUORIDE AMENDMENTS, IF REQUIRED, AND THEN IS FED INTO A SUBSURFACE FLOW LIMEROCK BED WHERE P PRECIPITATIN OCCURS. ANOTHER SMP COMPRISES THE THIRD AND FINAL TREATMENT STEP, PROVIDING FURTHER P REMOVAL FROM THE SATURATED EFFLUENT LEAVING THE LIMEROCK BED. THE MAJOR EMPHASIS OF THE PROPOSED RESEARCH IS ON DETERMINING THE OPTIMUM CONDITIONS FOR P COPRECIPITATION OF PRECIPITATION ON THE LIMEROCK, AND FOR ESTABLISHING SMP DESIGN AND OPERATIONAL CRITERIA FOR PRODUCTION AND "OPTIMUM" WASTEWATER FEED TT THE LIMEROCK FILTER. THE FOLLOWING EXPERIMENTS WILL BE CONDUCTED TO ESTABLISH CONCEPT FEASIBILITY; (I) A SCREENING STUDY ON THE GROWTH OF FOUR SUBMERSED MACROPHYTES IN SUGARCANE FIELD RUN OFF WATER, AND THE EFFECTS OF THE MACROPHYTES ON WATER COLUMN CONSTITUTENT LEVELS (PH, P, DOC, TSS); (II) LABORATORY SHAKER TABLE STUDIES ON THE USE OF LIMEROCK FOR REMOVING P FROM "SOILED" DISTILLED WATER, SUGARCANE FIELD RUNOFF, AND EFFLUENT FROM THE SUBMERSED MACROPHYTE TANKS; AND (III) A LABORATORY MICROCOSM EVALUATION OF THE COMPLETE INTEGRATED P REMOVAL SYSTEM (SMP-LIMEROCK FILTER-SMP), IN WHICH SOME OPTIMIZATION OF DESIGN (RELATIVE SIZES OF SYSTEM COMPONENTS) AND OPERATIONAL (HYDRAULIC RESIDENCE TIMES) CHARACTERISTICS WILL BE EVALUATED. SATURATION INDEXES AND KINETIC PARAMETERS WILL BE CALCULATED TO ASSIST IN IDENTIFYING THE CONTROLLING SOLID PHASE(S) (I.E. CALCITE, AMORPHOUS TRICALCIUM PHOSPHATE, HYDROXYAPATITE, FLUORAPATITE).