Energy recovery from human faeces via gasification: A thermodynamic equilibrium modelling approach

Abstract

HighlightsOn dry basis, typical human faeces contain 83 wt.% organic fraction and 17 wt.% ash.The LHV of dry human faeces ranged from 19 to 22 MJ/kg, values similar to wood biomass.Syngas from dry human faeces had LHV of 15–17 MJ/kg at equivalence ratio of ∼0.31.Energy is best recovered from moist human faeces at equivalence ratio above 0.6.Recoverable exergy potential from moist human faeces can be up to 15 MJ/kg.

An experimental investigation of the combustion performance of human faeces

“…The composition results of the three samples are in agreement with composition data of similar samples published elsewhere [23]. Onabanjo et al [23] showed that average composition from a set of 12 different human faeces sample was 51 ± 2 wt.% C, 7 ± 0 wt.% H, 4 ± 1 wt.% N, 21 ± 3 wt.% O and 17 ± 1 wt.% ash (dry basis). In addition, simulant faeces prepared following the same recipe used in this work had similar ultimate composition, i.e.…”

Thermodynamic assessment of human feces gasification: an experimental-based approach

“…Also, biosolids are included since such residue has an important amount of organic matter, with a similar composition to human feces in terms of proximate and ultimate analysis. A few authors refer to human fecal material as a categorized biomass [6,12,14,30], but the high levels of moisture content tend to approximate their classification as a biosolid. Indeed, while eliminating the water levels, the biomass category fits with more accuracy.…”

“…Some authors explored the thermochemical characterization of simulated feces on smoldering combustion [9][10][11], and gasification [6,12], but to reproduce feces is a very complex challenge considering its heterogeneous characteristics. Nevertheless, the results were very encouraging.…”

“…Yet, some contradictory results are found in the literature. For instance, Onabanjo et al [12] reported for real feces an average amount of 51% of ash, 17% of volatile matter and 32% of fixed carbon, and for simulant feces an average amount of 14% of ash, 86% of volatile and 0% of fixed carbon, both analysis on dry basis. Jurado et.…”

“…Ptasinski et al [19] performed a comparative study for the gasification exergy efficiency of different types of biofuels (wood, vegetable oil, sludge and manure) and benchmarked it against the gasification of coal. Pellegrini and De Oliveira [20] and Onabanjo et al [12] performed an exergy analysis of sugarcane bagasse and human feces gasification, respectively. All these works were conducted under theoretical assumptions, applying a thermodynamic equilibrium model with an adiabatic reactor.…”