Chemical pretreatment of Xyris capensis for enhanced methane yield

¹ Department of Mechanical Engineering Science, Faculty of Engineering and the Built Environment, University of Johannesburg, South Africa.
² Process Energy and Environmental Technology Station, Faculty of Engineering and Built Environment, University of Johannesburg, South Africa.

Abstract

This study investigated the impact of various chemical pretreatment methods on the biomethane production from Xyris capensis. The feedstock was treated with NaOH, HCl, H₂O₂, and oxidation using 3, 9, 5, and 75% H₂O₂ + 25% H₂SO₄, respectively. Pretreated and untreated substrates were analyzed for physicochemical characteristics and subjected to anaerobic digestion at a mesophilic temperature in a laboratory-batch experiment. The results show that chemical pretreatment significantly influences the physicochemical characteristics of Xyris capensis. It was noticed that the C/N ratios of 37.15, 37.26, 28.90, 27.63, and 28.02 were recorded for NaOH, HCl, H₂O₂, oxidative pretreatment, and untreated Xyris capensis, respectively. Compared to the untreated substrate, methane generation was enhanced by 20%, 107%, 68%, and 88% for NaOH, HCl, H₂O₂, and oxidative pretreatment, respectively. Therefore, chemical pretreatment presents a promising biotechnological approach for producing methane from lignocellulose feedstocks. The technique is sustainable due to its ability to recover and reuse chemicals, thereby reducing production costs.