Screening design of nutritional and physicochemical parameters on bio-hydrogen and volatile fatty acids production from Citrus Peel Waste in batch reactors

Abstract Different nutritional and physicochemical conditions to obtain H2 from Citrus Peel Waste (CPW) were evaluated. For this, a screening design was carried out using Plackett and Burman design, in order to verify the main significant conditions of this process. The variables studied were pH (5.5–8.5), temperature (30–44 °C), autochthonous inoculum (0.75–2.25 gTVS.L−1), allochthonous inoculum (1–3 gTVS.L−1) and substrate (5–15 g.L−1), headspace (40–60%) and nutritional medium components, such as yeast extract (0–1 g.L−1), CaCO3, NaCl and peptone (0–5 g.L−1). The most significant operational variables were pH (8.5), allochthonous inoculum (3 gTVS.L−1) and substrate concentration (15 g CPW.L−1), conditions that favored the highest H2 (13.29 mmol.L−1) and acetic acid productions (1340 mg.L−1). Escherichia (34.5%) and Clostridium (29.93%) were the main genera identified under these conditions.