Nutrients recovery during sewage treatment by aquatic plants: A comprehensive evaluation

Aquatic plants have great potentials for simultaneous sewage treatment and nutrients recovery. Herein, six aquatic plants (Alternanthera philoxeroides [A. philoxeroides], Pistia stratiotes, Eichhornia crassipe, Salvinia natans, Ludwigia adscendens and Myriophyllum aquaticum) were comprehensive evaluated through 15 qualitative and quantitative indicators. According to the evaluation system established using the Analytic Hierarchy Process, A. philoxeroides exhibited the best comprehensive performance. Further analyses revealed that A. philoxeroides showed good growth status and sewage treatment performance at different concentrations of nitrogen and phosphorus in municipal sewage (TN:21.6 mg/L-118.0 mg/L; TP:2.2 mg/L-11.1 mg/L). With the optimized initial planting density of 1944.8 g fresh weight/m2, the maximum relative growth rate (RGR) of A. philoxeroides was 0.06 g/(g•d) on the eighth day and the contribution of plant uptake to nitrogen and phosphorus removal were 34.7% and 66.0%, respectively. In this study, A. philoxeroides was proven to be a promising plant for recovering nitrogen and phosphorus from municipal sewage.