AVALIAÇÃO DA EFICIÊNCIA DO TRATAMENTO DE ESGOTO DOMÉSTICO POR MEIO DE SISTEMA ADAPTADO DE WETLANDS CONSTRUÍDOS

Abstract

Currently, the implementation of different water and sewage treatment systems is increasing, considering the aspects of public health and environmental sustainability involved. Thus, the present study aims to evaluate the functioning and effectiveness of wetlands system built in terms of hydrodynamics and prediction of the degradation and transformation kinetics of pollutants from domestic sewage. The evaluated parameters were: ammoniacal nitrogen (N-NH4+), chemical oxygen demand (COD), nitrite (NO2-), nitrate (NO3-), orthophosphate (PO4-P) and the monitoring of the parameters “hydrogen potential (pH), dissolved oxygen (OD) and sewage temperature T (°C) ”. This station is characterized by a septic tank (TS) followed by a wetland system built with vertical surface flow (WCFSV), followed by another wetland built with vertical subsurface flow (WCFSSV). The average flow of treated sewage in the systems was equal to (0.377 m³.day-1 ± 0.431). Statistical differences were obtained between the mean concentrations of COD and PO4-P for WCFSV1 and COD PO4-P and OD in WCFSSV2. Through Pearson's correlation, the strongest correlation (-0.590) was found for the parameters PO4-P and OD in WCFSSV2. Through the test with saline tracer, the model that best represented the distribution and stabilization of the values was the point 01 “WCFSV1” with one (R² = 0.89), and which presented a behavior consistent with a complete mixture flow. The system that best removed the COD from the sewer was the WCFSSV2 system (65%). The removal of N-NH4+ from domestic sewage was better represented by the WCFSSV2 treatment system (47%). The WCFSSV2 system showed better capacity for removing PO4-P from raw sewage (42%). In WCFSV1, the mathematical model that best represented the behavior of all parameters was that of Monod Multi, with R² values equal to “COD (0.54), N-NH4+ (0.56), NO3- (0.52) and PO4-P (0.52) ”. The WCSSV2 system presented the best efficiency values for removing pollutants from the affluent sewage, so it was found that compliance with the normal values of kinetics-hydrodynamics of the reactor, influenced the better treatment performance of this system.