Identificação microbiológica em lixiviados de aterro sanitário de diferentes fases de aterramento

Abstract

The municipal solid waste production is part of daily activities, being necessary to have the proper management of these materials. Landfill is one of the main methods of waste treatment and disposal, it is used in several countries, as Brazil. Over time, the organic matter landfilled is degraded, in different processes, by aerobic microorganisms, generating gases and leachate. The characterization of this microbiota allows the biodigestion understanding, also can improve the operational issue of landfills, such as cell optimization, leachate treatment and biogas use. This work intended to contribute with information about the sanitary landfill of São Leopoldo (RS), where leachate from five different phases, with different ages (0 year, 1 year, 4 years, 5 years, 7 years), were sampled in distinct months. According to physical and chemical analyses, landfill phases could be classified as mixed, with acid and methanogenic stages of degradation. The microbial communities diversty was assessed by enrichment and next generation sequencing analysis, using PCR barcoding from 16S rRNA gene, of samples from two landfill phases. Recent phase reactors, enriched with substrate for hydrolytic microorganisms, showed the phylum Bacteroides with higher abundance. The oldest phase reactors, enriched with three different substrates, showed higher abundance for the phylum Proteobacteria and the only one that had Archaea Domain was the reactor enriched with methanol. The sequence analysis of samples without enrichment, directly from leachates of the five phases, presented the phylum Proteobacteria with higher abundance (around 50%), followed by Firmicutes. In contrast, in the most recent phases Firmicutes (around 40%) was the most abundant phlyum, followed by Thermotogae. The phyla Gemmatimondetes and Chloroflexi were observed only in some phases. The Archaea domain was only 0.68% of total sequenced, all belonging to the phylum Euryarchaeota, mainly Methanobacteriales, Methanomicrobiales and Methanosarcinales orders.