Implantação e início de operação de uma estação de tratamento de esgoto com wetlands construídos em casa do estudante universitário

Abstract

Decentralized sewage treatment is a viable option, especially in isolated communities and difficult-to-access locations; Therefore, the use of constructed wetlands is an advantageous option, due to the low cost of operation and maintenance and simplicity of operation, in addition to the landscape beautification provided. The objective of the work was to monitor the installation and start of operation of a sewage treatment plant, next to the University Student House, at the Federal University of Santa Maria, in Frederico Westphalen. The station consists of a septic tank, suction well, wetlands constructed of saturated bottom vertical subsurface flow and ultraviolet radiation disinfection. The constructed wetlands have four modules: two have gravel and two have coarse sand as filtering media; one sand module has a saturation height of 0.15 m and the other, a saturation height of 0.25 m, as well as the crushed stone modules. The sand modules operate interspersed and the gravel modules operate simultaneously. Both modules were transplanted with Canna x generalis. The distribution of the influent is carried out by a pump, regulated by a float; each pulse has a volume of 950 liters, which was regulated by the float, with a flow rate of 45 liters/minute and a hydraulic application rate of 13.3 liters/m2 .pulse. The implementation followed current standards, as well as manuals from experts in the field. Necessary adjustments were made to the initial project, adding collection gutters, microbiological samplers and piezometers, to enable physical-chemical, microbiological and hydraulic analyses, respectively. Qualitative and quantitative analyzes were also carried out on the influent and effluent of the wetlands, in addition to establishing an operational routine for the station. The station achieved satisfactory performance, considering the start of operation, in accordance with legal requirements. Greater removal was achieved in wetlands constructed of sand, in all parameters, reaching 86% for chemical oxygen demand, 62% for ammonia nitrogen and 94% for total suspended solids. A drop in the pH value was also observed in wetlands built with sand. The station's operational routine was established, with daily, weekly, monthly and occasional activities. It can be concluded that all the modifications carried out contributed significantly to improving the station's performance and that it presents satisfactory removal rates.