Capim-tifton 85 cultivado em sistema alagado construído com elevadas taxas de aplicação

Abstract

Constructed wetlands (CWs) have been used for effluent treatment, especially as tertiary units. They present moderate cost of installation and considerable nutrient removal. The vegetation utilized in CWs can be used for animal feeding. In this paper, we evaluate the performance of Tifton 85 grass (Cynodon spp.) for the treatment of swine wastewater. The experiment was conducted for 131 days in three phases. Application rates reached levels of 6335, 464 and 240 kg ha-1 d-1 of COD, TKN and TP, respectively. At each cutting the green and dry mass and the levels of nitrogen, phosphorus and crude protein were quantified. It was found that there was an increase in the concentrations of crude protein, NTK and TP in the Tifton 85 grass tissues with increasing rate of surface nutrient application, but the dry matter yield decreased in the third phase, probably as a result of factors such as decreasing temperature and excess solids retained in the CW. Elevated organic application loadings reduced the development of Tifton 85 grass with respect to dry matter.