Simultaneous Enzymatic Cellulose Hydrolysis and Product Separation in a Radial-Flow Membrane Bioreactor

Abstract

Hydrolysis is the heart of the lignocellulose-to-bioethanol conversion process. Using enzymes to catalyze the hydrolysis represents a more environmentally friendly pathway compared to other techniques. However, for the process to be economically feasible, solving the product inhibition problem and enhancing enzyme reusability are essential. Prior research demonstrated that a flat-sheet membrane bioreactor (MBR), using an inverted dead-end filtration system, could achieve 86.7% glucose yield from purified cellulose in 6 h. In this study, the effectiveness of flat-sheet versus radial-flow MBR designs was assessed using real, complex lignocellulose biomass, namely date seeds (DSs). The tubular radial-flow MBR used here had more than a 10-fold higher membrane surface area than the flat-sheet MBR design. With simultaneous product separation using the flat-sheet inverted dead-end filtration MBR, a glucose yield of 10.8% from pretreated DSs was achieved within 8 h of reaction, which was three times higher than the yield without product separation, which was only 3.5% within the same time and under the same conditions. The superiority of the tubular radial-flow MBR to hydrolyze pretreated DSs was confirmed with a glucose yield of 60% within 8 h. The promising results obtained by the novel tubular MBR could pave the way for an economic lignocellulose-to-bioethanol process.

Hydrodynamic studies of innovative membrane reactor for enzymatic hydrolysis of lignocellulosic waste

“…A similar concept was applied by Al‐Mardeai et al. [ 24 ] In both cases, the reactor construction ensured a radial circulation direction of the feed. In contrast, Belafi‐Bako et al.…”

“…For example, Al-Zuhair et al [19] developed a jacketed cylindrical continuous stirred tank membrane reactor with vertical sides made of ultrafiltration membrane. A similar concept was applied by Al-Mardeai et al [24] In both cases, the reactor construction ensured a radial circulation direction of the feed. In contrast, Belafi-Bako et al [25] used a tubular membrane reactor with a porous stainless steel tube placed in a cylindrical vessel without mixing.…”