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 (30-37ºC) 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 d-1 of SEW and 8 kg d-1 of SOW, would produce about 1.5 Sm3biogas d-1 and substitute nearly 11 kg d-1 of firewood for cooking needs, avoiding black carbon particles emissions and inhalation in households. Alternatively, 10 biogas-lamps could work for 3 hours d-1 or a 1-kW-electric-power generator run for over 2 hours d-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.