Estimation of plant productivity and nutrient extraction capacity along the length of horizontal subsurface flow constructed wetland treating swine wastewater

Abstract

The plant productivity and extraction capacity of nutrients present in swine wastewater (SWW) were quantified over 60 days in three horizontal subsurface flow constructed wetlands (HSSF-CW) grown with three different plant species (Typha latifolia, Alternanthera philoxeroides and Cynodon dactylon). The results show the decay of the dry matter yield (DMY) and the nutrient extraction capacity (NEC) by the plants throughout the system, which gave rise to the equations that relate these parameters to the hydraulic retention time (HRT) for each species. When possible, general equations that are independent of the plant species were also evaluated. The best model fit for the dry matter yield and N-total, N-ammoniacal, N-nitrate and P extraction by plants as a function of HRT was the decreasing potential and for K extraction was the linear regression. The coefficients of determination of equations for the species Alternanthera philoxeroides and Cynodon dactylon were, for the most part, higher than 0.8. On the other hand, the general equations presented coefficient of determination greater than 90% in all cases.