Nitrogen and phosphorus removal by cypress swamp sediments

Removal of nutrients from wastewater (effluent) by sediments in cypress swamps was studied in laboratory leaching columns filled with wet surface sediments. Columns were leached with low-nutrient groundwater, treated wastewater, and treated wastewater amended with nitrate (20 to 30 mg N L^?1) and phosphate (9.5 mg P L^?1) for 21 mo. From 99 to 100% of the nitrate-nitrite and P was removed from the amended wastewater eluants throughout the investigation; average concentrations of nitrate-nitrite and P in effluent from amended wastewater columns did not exceed concentrations in leachate from columns eluted with groundwater. Ammonium removal was approximately 50% in columns receiving treated wastewater. Sediments of cypress swamps have a large capacity to remove nutrients from secondary effluent.