NITRIFICATION AND DENITRIFICATION IN AERATED LAGOONS COUPLED WITH ARTIFICIAL WETLANDS

The HiLand Acres Water and Sanitation District in Colorado upgraded an aerated lagoon system and constructed a new subsurface flow (SSF) artificial wetland to improve wastewater treatment performance. Lagoon mixing energy was increased to promote aeration and nitrification. The SSF wetland filters the lagoon effluent, reducing suspended solids and algae prior to discharge to the receiving stream. The coupled lagoon/wetland system reduces BOD5 and TSS to less than 10 mg/L each. Denitrification in the anoxic wetland removes most of the nitrate produced in the aerated lagoon component. The coupled lagoon/wetland process removes over 90 percent of the ammonia nitrogen and more than half of the total nitrogen in the influent wastewater during warm weather.