Effects of capping on microbial populations and contaminant immobilization in an old unlined landfill

Author(s)

Morita, Alice Kimie Martins ; Sakamoto, Isabel Kimiko ; Varesche, Maria Bernadete Amancio ; Wendland, Edson

• Document type: Journal article
• Source: Environmental Science and Pollution Research; v. 30, n. 26, p. 15-pg., 2023-06-01.

Abstract

This research aimed at evaluating the effects of capping on the mitigation of impacts generated by a closed unlined landfill in SAo Carlos, SP, Brazil. Physicochemical and microbiological analyses (16S rRNA sequencing) of buried solid waste samples were performed, in capped and uncapped areas. Even though leachate pockets could still be encountered in capped areas, the capping construction reduced oxygen availability and created more reducing conditions, propitiating the development of sulfate-reducing bacteria and possibly contributing to the precipitation of the metals Pb, Cd, Ni, Co, As, and Zn as metal sulfides, causing their immobilization. The microbial populations adapted to the anaerobic conditions created under capped zones belonged to the phyla Firmicutes, Chloroflexi, and Euryarchaeota and the genera Methanosaeta, Hydrogenispora, Smithella, and Gelria. Differently, the phyla Acidobacteria, Proteobacteria, Bacteroidetes, and Actinobacteria were more abundant in samples from the uncapped zones, in which the abundance of different genera varied homogeneously. Methanogenic activity was not impaired by the intervention measure, as assessed by the specific methanogenic activity (SMA). Capping of old unlined landfills brings benefits to the immobilization of metals and does not impair microbial degradation, being effective for the mitigation of impacts on soils and water resources. (AU)

• FAPESP's process: 15/03806-1 - Water availability and quality threats in a Guarani Aquifer System outcrop zone
• Grantee: Edson Cezar Wendland
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Thematic Grants
• FAPESP's process: 18/24615-8 - Effects of partial capping in the contaminants mobilization and microbial degradation in a closed waste deposit
• Grantee: Alice Kimie Martins Morita
• Support Opportunities: Scholarships in Brazil - Doctorate