Florida Passive Nitrogen Removal Study Additional Sampling Report
The report presents findings from the Florida Passive Nitrogen Removal Study (PNRS), which aimed to investigate alternative methods for nitrogen removal in onsite wastewater treatment systems (OWTS) in Florida. The study was motivated by concerns over nitrogen loading from septic systems, particularly in sensitive environmental areas. The PNRS focused on "passive" systems that minimize mechanical intervention, relying instead on reactive media for treatment.
The experimental phase involved operating three two-stage filter systems over an extended period, using actual septic tank effluent (STE) from a field site in Hillsborough County. The two-stage systems consisted of an unsaturated aerobic filter (Stage 1) followed by a saturated anoxic filter (Stage 2). The study evaluated various media types, including clinoptilolite, expanded clay, and granular rubber, with elemental sulfur used in the denitrification stage.
Key findings included:
- The systems achieved high nitrogen removal efficiencies, with total nitrogen (TN) removal rates averaging 96.8% for clinoptilolite, 95.1% for expanded clay, and 86.6% for granular rubber.
- Effluent TN concentrations were significantly reduced, with average values of 2.2 mg/L for clinoptilolite and 3.2 mg/L for expanded clay.
- The study also monitored biochemical oxygen demand (BOD) and found removal efficiencies exceeding 94% across all media types.
- The report detailed the operational parameters, including hydraulic loading rates, and provided insights into the performance of the media over time.
The report concluded that the two-stage passive systems demonstrated effective nitrogen and organic matter removal, supporting the feasibility of using such systems in Florida's OWTS to mitigate nitrogen pollution.
The Florida Passive Nitrogen Removal Study is significant for its contributions to environmental health and wastewater management practices. As Florida faces challenges related to population growth and the sustainability of centralized wastewater treatment systems, this study offers valuable insights into alternative, cost-effective solutions for managing nitrogen pollution from onsite systems. The findings support ongoing discussions about improving water quality in sensitive ecosystems and provide a framework for future research and implementation of passive nitrogen removal technologies. The report serves as a resource for policymakers, environmental engineers, and public health officials seeking to enhance wastewater treatment practices while protecting Florida's water resources.
