Nitrogen removal and recovery from lagoon-pretreated swine wastewater by constructed wetlands under sustainable plant harvesting management.

A series of three-stage pilot-scale surface flow constructed wetlands (CWs) planted with Myriophyllum aquaticum were fed with three strengths of lagoon-pretreated swine wastewater to study nitrogen (N) removal and recovery under sustainable plant harvesting management. The CWs had mean removal efficiency of 87.7-97.9% for NH4+-N and 85.4-96.1% for total N (TN). The recovered TN mass via multiple harvests of M. aquaticum was greatest (120-222 g N m-2 yr-1) when TN concentrations were 21.8-282 mg L-1. The harvested TN mass accounted for 0.85-100% of the total removal in the different CW units. Based on mass balance estimation, plant uptake, sediment storage, and microbial removal accounted for 13.0-55.0%, 4.9-8.0%, and 33.0-67.5% of TN loading mass, respectively. The results of this study confirm that M. aquaticum is appropriate for the removal and recovery of nutrients in CW systems designed for treating swine wastewater in conjunction with sustainable plant harvesting strategies.