4th UF Water Institute Symposium Abstract

Submitter's Name Grant Weinkam
Session Name Poster Session: Water quality protection and treatment
Poster Number 52
Author(s) Grant Weinkam,  University of Florida (Presenting Author)
  Sustainable phosphorus management in land applied reclaimed water scenarios
  Florida leads the nation in waste water effluent/reclaimed water use, at over 700 million gallons per day, and land applies over 75% of this volume. While these effluent waters are treated to reduce pathogen loads, phosphorus (P) concentrations can still be substantial, especially in long term application scenarios. Currently an estimated 3.3 million pounds of P are reintroduced to the landscape yearly (assuming effluent=2 mg P/L), compared to only 50,000 pounds that would be applied if irrigated with ground water (at ground water = 0.03 mg P/L). Research suggests that under long term applications of P receiving systems can reach a state at which they are no longer able to assimilate further loading potentially resulting in landscapes that are actively leaching and eroding P rich particulate matter to receiving hydrologic systems. This statement can be especially relevant given the large proportion of sandy soils in Florida that contain, relatively, low physical/chemical ion exchange capacity and high hydraulic conductivity, thus increasing the potential for water quality impairment. Due to the increasingly stringent allowable surface water P concentrations and many uncertainties regarding the long term fate and transport of P this research seeks to determine how different soil conditions and reclaimed water loading amounts have or can alter the leaching profile in Florida soils. Field sampling and lab studies at different reclaimed water sprayfield sites are used to determine the relative change in P sequestration potential with depth, using soil phosphorus saturation capacity (SPSC) analyses, and potential leaching risk in lab core experiments. The resulting information improves fundamental understanding of soil-phosphorus transport dynamics and provides insights into alternative techniques for the long term environmental sustainability of reclaimed water usage.