Análise de ciclo de vida de unidade integrada de anaerobiose + wetlands construídos em configurações floating + fluxo vertical + filtro misto tratamento de efluente urbano.

Abstract

The investigation of the technical feasibility of decentralized effluent treatment systems has received considerable attention in recent years, as it seeks to solve the problem of sanitation in contexts in which conventional treatment techniques are not attractive. Constructed Wetlands (CWs) have been considered as a promising technology in this sense, being studied by many researchers around the world and with several successful cases of application in the treatment of effluents at different scales. The study of the environmental sustainability of these systems, through tools such as Life Cycle Analysis, seeks to answer fundamental questions about the impact and potential benefits to the environment arising from the use of wetlands as an alternative to other treatment techniques. Given this context, this work was composed of a bibliometric analysis, reviewing the existing publications about the application of Life Cycle Analysis to Constructed Wetlands systems, followed by the application of a Life Cycle Analysis to an integrated wastewater treatment system composed of an Anaerobic Reactor/Biofilter, floating treatment wetland, subsurface vertical flow wetland integrated with Microbial Fuel Cells, and a Reactive Bed Filter. In the bibliometric analysis, data was obtained from the Web of Science database and analysed with the software VosViewer 1.6.16. The research found 87 articles published between 1999 and 2021, in which terms such as “activated sludge”, “costs” and “pollutant removal” stood out. It was found that several authors agree on the fact that the lack of studies on the economic and social impacts of CWs is a problem. In the application of the LCA, the software SimaPro 8.0.4 was used, with a functional unit of 2.9 m3 week-1 of effluent and a reference flow of 20 years in three scenarios, considering the same equipments. The first scenario considered the use of electric energy to pump the effluent between the equipments, the second scenario considered gravity transport. A third scenario was also considered, comprising the replacement of some of the construction materials by alternatives with less environmental impact. The results showed a contribution of 84.8% (in Single Score - Pt) to the materials needed to build the system on a pilot scale in Scenario 1, as well as 15.2% for the operation of the Scenario 2 system, without the use of electrical energy for pumping, which allowed the conclusion that the difference in operating conditions between the two scenarios was not significant. Scenario 3 showed that replacing materials such as fiberglass reinforced with polyester and high-density polyethylene with alternatives such as fiber cement and recycled polymers can significantly reduce the environmental impact in several impact categories. The results showed the importance of studies of materials and operating conditions of wetland systems built to ensure environmental efficiency, but subsequent studies considering economic and social aspects of this type of system are necessary to better assess its sustainability.