Abstract

Empirical Buswell’s equation for biohydrogen is a stoichiometric model to identify elemental composition and thermal properties of dark fermentation effluent. Biodegradability index, energy conversion efficiency, and electron conversion efficiency are applied to evaluate the degradability performance of organic matter. Based on empirical Buswell’s equation for biohydrogen, experimental heat of dark fermentation is determined by mass percentages of elements of organic matter and experimental biohydrogen yield. In this study, the calculation of theoretical and experimental heat of dark fermentation for dark fermentation effluent are demonstrated by step-by-step procedures. The macroscopic energy-based metric, heat conversion efficiency, is established and defined as the ratio of experimental heat of dark fermentation to theoretical heat of dark fermentation. The study concludes that: (i) both theoretical and experimental heat of dark fermentation are endothermic reactions, (ii) theoretical higher heating value and standard heat of formation of dark fermentation effluent in kilojoule per gram is greater than those of organic matter, (iii) heat conversion efficiency is identical to biodegradability index, (iv) heat conversion efficiency is less than energy conversion efficiency, and (v) heat conversion efficiency and electron conversion efficiency are identical.

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