Desempenho do Sistema Combinado Tanque Séptico mais Sistema de Alagados Construídos de Escoamento Vertical (TS+SACV) na remoção de poluentes de esgoto sanitário

Abstract

Brazil has been looking for alternatives to sanitary sewage treatment systems that include simplicity of operation and low implementation costs. Nowadays, septic tanks are widely used, however, the system has moderate organic matter removal efficiency, requiring post-treatment to achieve an acceptable degree of removal. As an alternative to improve the removal of sanitary sewage pollutants, constructed flooded systems present themselves as a viable option for septic tank aftertreatment, as they do not depend on large energy or maintenance costs and are capable of ensuring high treatment efficiency. This work has evaluated the performance of combined septic tank system plus built-up vertical flow (TS + SACV) wetland system in the removal of sewage pollutants. The research was carried out at the Federal University of Amazonas facilities in the municipality of Humaitá, with operations beginning on August 17, 2019. The collections were performed at four system points (five repetitions) and took place for three consecutive weeks, always during the period, in the afternoons of October 2019. To verify the performance of the TS + SACV system, the following parameters were carried out: Potential of Hydrogen (pH), Temperature (T), Electrical Conductivity (EC), Dissolved Oxygen (DO), Total Solids (TS), Sedimentable Solids (SedS), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and Total Phosphorus (TP). The combined system resulted in a decrease in pH, T and EC with values of 6.1, 27.7 ° C and 80 μS / cm, complying with the release limits established by CONAMA Resolution No. 430/2011. Dissolved oxygen obtained effluent elevations when circulating through the combined system showing an average value of 5.44 mg / L. The variation of total and sedimentable solids was expressive showing decrease in concentrations and in values of 22.5 mg / L (TS) and 0 mg / L (SedS), demonstrating the damping capacity of TS + SACV system. The treated effluent from TS + SACV system had a decay in BOD and COD concentrations ranging from 128.92 to 22.05 mg / L, and 264.05 to 51.97 mg / L, respectively. The identified phosphorus value after treatment was 2.12 mg / L. The decrease of this nutrient is attributed mainly to SACV performance through the vegetation cover. The combined system presented efficiencies higher than those recommended by the current CONAMA resolution N° 430/2011, with average removal percentages of 85.3% for Total Sodium, 71.4% for BOD, 74.0% for COD and 76.8% for Phosphorus, indicating the feasibility of applying this technology. Thus, it is concluded that the Septic Tank Combined System plus Vertical Runoff Constructed Wetland System is efficient in removing sewage pollutants and capable of meeting effluent release requirements, according to the CONAMA Resolution N° 430/2011 prerogatives.