Domestic low-tech anaerobic digesters in Guiné-Bissau: a bench-scale preliminary study on locally available waste and wastewater
2015
Gallia, Andrea | Veronesi, Davide | Embaló, Umaro Spencer | Pongiglione, Filippo | Adani, Fabrizio | Schievano, Andrea
Solid organic waste (SOW) and sewage (SEW), in developing contexts as Guiné-Bissau, can be converted into biogas in domestic low-tech anaerobic digesters (AD), avoiding their dispersion in the environment (cause of infective diseases) and simultaneously providing local sustainable/clean fuel to substitute firewood (cause of deforestation and respiratory diseases). Here, SOW and SEW, sampled from local markets/households of Bissau City, were processed in a bench-scale reactor, to define the potentials of low-tech mesophilic (30–37 °C) AD in removing pathogen microbial population, responsible for infective diseases spreading through untreated SOW/SEW and in domestic fuel generation in substitution to firewood. Pathogens removal above 99.9 % were obtained for E. coli and Streptococci. Considering a target scenario (4-persons household unit), a low-tech AD of 2.35 m³ functional volume, co-digesting 32 L day⁻¹ of SEW and 8 kg day⁻¹ of SOW, would produce about [Formula: see text] and substitute nearly 11 kg day⁻¹ of firewood for cooking needs, avoiding black carbon particles emissions and inhalation in households. Alternatively, ten biogas lamps could work for 3 h day⁻¹ or a 1-kW electric power generator run for over 2 h day⁻¹, with important socio-economic benefits. Finally, firewood substitution and the use of digestate as soil conditioner can simultaneously contribute in limiting deforestation and desertification, particularly in transition sub-Saharan tropical areas, such as Guiné-Bissau.
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