Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/15/1998
Publication Date: N/A
Technical Abstract: Constructed wetlands can be used to remove significant portions of nitrogen from swine wasterwater. Our objectives were to assess the redox conditions of the constructed wetland soil and the limiting factors for denitrification. Platinum electrodes and denitrification enzyme assays were used. The treatment wetlands consisted of six 3.6-m x 33.5-m cells. They contained rush and bulrushes or bur-reed and cattails. Nitrogen loading rates of 3 to 25 kg/ha/day. More than 80% of the applied nitrogen was removed. Denitrification enzyme assays indicated that wetlands contained sufficient carbon for high rates of denitrification and that nitrate was the limiting factor for denitrification. The redox conditions of the wetland soils were highly reducing, generally 100 to -200 mV. These reducing conditions likely hampered nitrification of the wastewater which was predominately in the ammonia form. We are currently investigating methods of pre-wetland nitrification.