Abstract
Despite solid wastes’ landfill disposal limitation due to recent European legislation, landfill leachate disposal remains a significant problem and will be for many years in the future, since its production may persist for years after a site’s closure. Among process technologies proposed for its treatment, microbial fuel cells (MFCs) can be effective, achieving both contaminant removal and simultaneous energy recovery. Start-up and operation of two dual-chamber MFCs with different electrodes’ structure, fed with mature municipal solid waste landfill leachate, are reported in this study. Influent (a mix of dairy wastewater and mature landfill leachate at varying proportions) was fed to the anodic chambers of the units, under different conditions. The maximum COD removal efficiency achieved was 84.9% at low leachate/dairy mix, and 66.3% with 7.6% coulombic efficiency (CE) at a leachate/dairy ratio of 20%. Operational issues and effects of cells’ architecture and electrode materials on systems’ performance are analyzed and discussed.
Highlights
Municipal solid waste (MSW) disposal is a problem with no easy or unique solution
Microbial fuel cells rely on biological oxidation of wastewater, which effectiveness strongly depends on the nature of the substrate
Observed energy production did not reflect a specific trend correlated to the varying Landfill leachate (LL) fraction in the feed; upon examination of the results, it can be assessed that the most favorable operating condition was observed in phase 4 (15% leachate), where maximum output power peaks were recorded for both microbial fuel cells (MFCs)
Summary
In 2015, 242.3 Mt of MSW was produced in the European Union, 62 Mt of which discarded in landfills. In this context, produced about 29.5 Mt MSW in 2015, of which 7.8 landfilled (ISPRA 2017). Despite the reduction of MSW landfill disposal due to recent European legislation (EU 2018a; EU 2018b), leachate generated from decomposition of MSW in landfills is still a significant problem nowadays and will be for many years in the future, since its production may persist for years after a site’s closure. Leachate characteristics are quite variable, affected by landfill construction and age, local meteorology, waste type, and composition, normally high in COD and ammonia content (Kulikowska and Klimiuk 2008; Youcai 2018). Leachate contains organic constituents that may be degraded by bacteria already within the landfill, but it contains ammonia at high concentrations (Kjeldsen et al 2002), heavy metals, and other refractory organic and inorganic compounds that may accumulate in it, inducing bio-toxicity or bioinhibition (Renou et al 2008; Karrer et al 1997)
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