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

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.

Fouling Reduction Via Air Backpulsing in Dairy Wastewater Microfiltration

Membrane fouling mitigation in dairy wastewater microfiltration was investigated through air back pulsing. Flat sheet membrane module with pore size of 0.1 mm was used. The model dairy wastewater was prepared by skim milk diluted with distilled water (milk:water = 1:2). The effect of three parameters, including air back pulsing pressure (pb), back pulsing frequency (f), and back pulsing duration (d) on fouling control was investigated. It was found that high pressures of air in short durations of back pulsing can improve the filtration process and result in higher amounts of permeate. However, it is anticipated that beyond the region of study, very high frequency would not be helpful. Very high frequencies mean short back pulsing durations, and this might result in loss of positive effect of back pulsing. The maximum permeate amount obtained using back pulsing assisted filtration process was 83% higher than the one obtained without back pulsing.

Fouling Reduction Via Air Backpulsing in Dairy Wastewater Microfiltration

Membrane fouling mitigation in dairy wastewater microfiltration was investigated through air back pulsing. Flat sheet membrane module with pore size of 0.1 mm was used. The model dairy wastewater was prepared by skim milk diluted with distilled water (milk:water = 1:2). The effect of three parameters, including air back pulsing pressure (pb), back pulsing frequency (f), and back pulsing duration (d) on fouling control was investigated. It was found that high pressures of air in short durations of back pulsing can improve the filtration process and result in higher amounts of permeate. However, it is anticipated that beyond the region of study, very high frequency would not be helpful. Very high frequencies mean short back pulsing durations, and this might result in loss of positive effect of back pulsing. The maximum permeate amount obtained using back pulsing assisted filtration process was 83% higher than the one obtained without back pulsing.

(Polyphenyl Sulfone - Polyether Sulfone) Blending to Performance Flat Sheet Membrane to Remove Some Heavy and Radioactive Elements from Phosphogypsum Waste

In this research, the traditional version of the phase inversion method was used to fabricate a flat sheet of a blended membrane. The method was involved using a polymer that blends polyether sulfone (PES) varied proportions (0,3,4 and 5 wt.%), and polyphenyl sulfone (PPSU) was 20wt%. It was found that with the addition of PES, the membrane properties increased, the best properties were with 4%wt. The ratio was chosen PES 4wt% to study the effect of time, temperature, and pressure on the rejection of heavy and radioactive elements. The increase in the porosity was with the addition of 4% PES. The rejection of heavy and radioactive elements for thUF membrane increases with increasing of the operating pressure and time. While by increasing the temperature, the rejection of heavy and radioactive elements for thUF membrane decreased. The rejection of K, Th, and Pb are higher than other elements, the order of the rejection is K˃Th˃Pb˃U˃Cd˃Zn˃Cu>Ni.

Recovery of Filtered Particles by Elastic Flat-Sheet Membrane with Cross Flow

After filtration, filtered residue is recovered by a spoon, during which, the structure of the residue is destroyed, and the activity of the microorganism would be reduced. Thus, a more efficient recovery method of filtered residue is required. This study addressed the recovery method of filtered residue by the restoration of an elastic membrane, followed by cross flow. An elastic membrane composed of a copolymer of poly(ethylene glycol) diacrylate and polyacrylonitrile was prepared by photopolymerization. The pore diameter of the obtained membrane was about 10 μm. Silica particle (1 and 10 μm) and Nannochloropsis sp. (2 μm) suspension was filtered, demonstrating that silica particles of 10 μm were filtered perfectly, whereas the filtration percentage of 1 μm silica particles and Nannochloropsis sp. was lower. After the filtration, the applied pressure was released to restore the elastic membrane which moved the filtered particles up, then the filtered residue was recovered by cross flow above the membrane, demonstrating that 71% of the filtered 10 μm silica particles was recovered. The elastic behavior of the membrane, along with the cross flow, has the potential to be used as a technique for the recovery of the filtered residues. This proposed scheme would be used for the particle recovery of ceramics, cells, and microorganisms from a lab scale to a large-scale plant.