Abstract

Biohydrogen is widely generated by dark fermentation and two-stage anaerobic digestion. Anaerobic digestion can be chemically represented by the Buswell’s equation, which is based on elemental composition of organic matter. When compared to Buswell’s equation for biomethane, its equation for biohydrogen has been given less attention. In this article, the nature of Buswell’s equation for biohydrogen is introduced by using the H-atom method. The mean oxidation number of organic carbons is employed as a metric for counting theoretical quantity of biohydrogen and parameters of Buswell’s equation for biohydrogen. Based on an empirical formula and mean oxidation number of organic carbons, the general Buswell’s equation for biohydrogen is developed. The mathematical relationships among mean oxidation number of organic carbons, empirical formula, quantity of biohydrogen, theoretical biohydrogen potential, and biohydrogen percent yield are also established. Biowastes and bio-substrates are chosen to demonstrate this notion.

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