Evaluation of Phosphorus and Nitrogen levels in pretreated household effluents to irrigate Axonopus compressus

Abstract

The treated sewage effluent, when used for irrigation, can allow that the soil and plants absorb the nutrients and organic material in that effluent. It can be said that, by absorbing N and P contents present in the effluent, the soil-plant system will serve as a "polishing" system of the wastewater and may improve its quality. This study aims at evaluating total Phosphorus (P) and total Nitrogen (N) levels in the final effluent, leached through the soil-plant system in which the grass Axonopus compressus was the species chosen for the study. The experiments were conducted between June and October 2013, at Cooperative of Energy Distribution Teutônia (CERTEL ENERGIA) and at Regional Cooperative of Development Teutônia (CERTEL). Nine bench tests prototypes (BPs) were carried out in laboratory scale, divided in triplicates. The control samples (T) were irrigated solely with rainwater, the T1 samples were irrigated with 100% of pretreated household effluent, and the treatments T2 with 50% rainwater over 50% household pretreated effluent during 31 days. The grass of Axonopus compressus species contributed to the polishing of the effluent so that the levels of N and P were found in lower concentrations in the final effluent of all treatments. The samples corresponding to the T1 showed higher removal efficiency, being 59.73% for P and 75.06% for N, while the T2 samples only met the emission limits for P and N established by Resolution Number 128/2006, of the State Council for the Environment (CONSEMA).