Onabanjo
Somorin, T., Kolios. A.J., Parker, A., McAdam, E., Williams, L., Tyrrel, S.
Faecal-wood biomass co-combustion and ash composition analysis, Fuel 2013,
781-791
Fuel blending is a widely used approach in biomass combustion,
particularly for feedstocks with low calorific value and high moisture
content. In on-site sanitation technologies, fuel blending is proposed
as a pre-treatment requirement to reduce moisture levels and improve the
physiochemical properties of raw faeces prior to drying. This study
investigates the co-combustion performance of wood dust: raw human
faeces blends at varying air-to-fuel ratios in a bench-scale combustor
test rig. It concludes with ash composition analyses and discusses their
potential application and related problems. The study shows that a
50:50 wood dust (WD): raw human faeces (FC) can reduce moisture levels
in raw human faeces by ∼40% prior to drying. The minimum acceptable
blend for treating moist faeces without prior drying at a combustion air
flow rate of 14–18 L/min is 30:70 WD: FC. For self-sustained ignition
and flame propagation, the minimum combustion temperature required for
conversion of the fuel to ash is ∼400 °C. The most abundant elements in
faecal ash are potassium and calcium, while elements such as nickel,
aluminium and iron are in trace quantities. This suggests the potential
use of faecal ash as a soil conditioner, but increases the tendency for
fly ash formation and sintering problems.
