Development of a novel fractal-like kinetic model for elucidating the effect of particle size on the mechanism of hydrolysis and biogas yield from ligno-cellulosic biomass. (April 2018)

• Record Type: Journal Article
• Authors: Momoh, O.L.Y.; Ouki, S.
• Is Part Of: Renewable energy. Volume 118(2018)
• Page Start: 71
• Page End: 83
• Publication Date: 2018-04
• Subjects: Fractal-like kinetics -- Fractal exponent -- Particle size -- Biogas yield -- Inaccessible regions; Renewable energy sources -- Periodicals; Power resources -- Periodicals; Énergies renouvelables -- Périodiques; Ressources énergétiques -- Périodiques; 333.794
• DOI: 10.1016/j.renene.2017.11.005
• Languages: English
• ISSNs: 0960-1481

Abstract

Abstract: The effect of particle size on hydrolysis and biogas production kinetics from a typical ligno-cellulosic biomass was assessed by studying the anaerobic co-digestion of fixed amount of rice husk and cow dung mixture using a newly developed fractal-like kinetic model. British Standard (BS) sieves were used to obtain varying particles size fractions ranging from 0.150 to 0.212 mm, 0.212–0.300 mm, 0.300–0.600 mm, 0.600–1.000 mm and 1.000–1.700 mm from oven dried, milled rice husk and pulverized, dried cow dung respectively. These particle size fractions from both biomass were mixed in a ratio of 1:1 after which, they were loaded into batch reactors and digested anaerobically at ambient conditions for 75 days. Hydrolysis of ligno-cellulosic biomass was observed to depend on the fractal exponent (h), which indexed the presence of inaccessible regions in ligno-cellulosic biomass. Also, hydrolysis was observed to depend on two other intrinsic factors that comprised of the initial hydrolytic rate ( X o Y k o ′ ) and overall affinity constant ( k o ′ S o ) . Larger particle size fractions were associated with higher affinity but lower initial hydrolysis rate while, smaller particle size fractions were associated with lower affinity but higher initial hydrolysis rate. In addition, the fractal model compared favorably with the popular modified Gompertz equation. Graphical abstract: Highlights: Cumulative biogas yield was inversely proportional to particle size fractions. Smaller particle size fractions were associated with the smaller fractal exponents. Larger particle size fractions were associated with higher fractal exponents. Hydrolytic bacteria showed higher specific affinity for the larger particle size fractions. Higher hydrolysis rate and biogas yield were associated with smaller particle size fractions.