Análise de ciclo de vida do sistema de tratamento de lixiviado em um aterro sanitário municipal

Abstract

The Landfill Leachate Treatment Station (ETL) has the function of treating raw leachate and complying with the release standards required by federal environmental legislation (CONAMA Resolutions No. 357/2005 and 430/2011) and state legislation, in the same in this case, Normative Instruction No. 01/2018 of Alagoas. Despite contemplating launch standards, the legislation does not consider an expanded view of all impacts caused during the operational lifecycle of ETL. In this sense, we sought to assess the environmental performance of the operation of the leachate treatment system from the Benedito Bentes Waste Treatment Center (CTR / BB), in Maceió - AL, through the Life Cycle Assessment (ACV). Six ETL operation scenarios were considered, being a real scenario and five hypotheticals. The real scenario was based on the original design: anaerobic lagoon, preaeration lagoon, aerated lagoon, physicochemical system by coagulation, flocculation and decantation, filtration system by activated carbon and zeolite and nanofiltration system. The hypothetical scenarios were based on the replacement of the biological treatment system for UASB-Wetland, and not using resources and environmental gains, that is, using biogas to generate electricity and reducing greenhouse gases. To carry out the LCA, primary and secondary data were captured in the construction of the Life Cycle Inventories (ICVs), using data from the CTR / BB, as well as from the Ecoinvent v database. 3.5, compiled using OpenLCA software. The chosen evaluation method was the CML - baseline IA - World 2000, which evaluated the following impact categories: open depletion, abiotic depletion, acidification, eutrophication, freshwater ecotoxicity, global warming (GWP100a), human toxicity, marine ecotoxicity, ozone layer depletion, photochemical oxidation and terrestrial ecotoxicity. The results induced that Scenario 6 (hypothetical) was the one that presented the best research performance, becoming the system with the lowest environmental impact. On the other hand, Scenario 1 (actual) presents the worst LCA performance, except for the categories: Global Warming (GA) and Photochemical Oxidation (OF). The research also highlighted Polyaluminium Chloride (PAC) as the main factor causing environmental impact in all scenarios and Methane (CH4) as the second factor for some scenarios. Despite this, Methane feeds greater use of resources and environmental gain, no longer being released directly into the atmosphere to be used as a source of electricity generation. This change caused a decrease in the impact of more than 70% for the AG and OF categories. Thus, an ETL can be optimized in terms of environmental performance, not only by reducing the environmental impacts of the operating system, but also by taking advantage of resources present in the leachate.