An Integrated Process of Value Addition to Citrus Waste and Performance of Fenton Process for Its Conversion to Biogas

Citrus fruits are commercially important fruit crop all over the world. About 50–60% of citrus fruit is considered waste including peels and its handling is costly at municipal and industry levels. Citrus wastes in general show a low pH (3–4), relatively high water content and organic matter. Its composting is not recommended, as it has inherent low pH and presence of high concentration of limonene in essential oils that slow down its biological decomposition due to inhibitory activity. Anaerobic digestion for biogas production seems to be a technically sustainable way to valorise by suitable pre-treatment methods. Present study shows extraction of essential oil in minimum requirement of water (1:1 w/v) for hydro-distillation that yields about 2% essential oil from fresh peels. Further, pre-treatment of left over de-oiled biomass with of 30% Fenton’s reagent treatment show biogas and methane production up to 322.63 ml biogas/g VS feed and 122.48 ml methane/g VS feed, respectively under mesophilic condition which is superior to conventional treatment.