Fiber extraction and energy recovery from Cocos nucifera Linn mesocarp residues employing steam explosion and anaerobic digestion

Abstract

Steam explosion of coconut mesocarp was performed in lab-scale and pilot-scale experiment. All products, namely, fiber, dust, and liquid phase, were utilized from a single biomass feedstock. Dry basis yield of the fiber product was around 22–51 %. Effects of steam explosion on coconut mesocarp involved partially degradation of hemicellulose and lignin as well as ash removal, particularly K and Cl. Well-oriented cell structure with dense cell wall area were observed in fiber product implied better strength compared to the original fiber. Tensile strength of the coconut fiber produced from lab-scale and pilot-scale steam explosion was in range of 16−23 MPa at 6–12 % breaking elongation and 41 MPa at 4.5 % breaking elongation, respectively. Thermal conductivity coefficient of the fiber sheet was 0.0486 ± 0.012 W/m‧K. The saturated moisture adsorption was 5.6 % after 9 h, lower than the moisture regain of other plant fibers (8.5–14 %). Biomethane potential test showed that the biogas production from liquid product were 446.0 and 457.2 L/kgCOD (methane concentration of 65 %) for FM ratios of 1:2 and 1:3, respectively. This research proposed the concept of coconut mesocarp conversion by steam explosion that the variety of products can be produced without waste generation.