The immobilisation of Chlorella vulgaris 211/11B entrapped in combinations of natural matrices to simplify the harvesting process was demonstrated in this study. Three combinations of matrices composed of calcium alginate (CA) and sodium alginate (SA), sodium carboxymethyl cellulose (CMC) and SA, and mixed matrices (SA, CA, and CMC) were investigated. The number of cells grown for each immobilised matrix to microalgae volume ratios (0.2:1-1:1) were explored and compared with using SA solely as a control. The optimum volume ratios obtained were 1:1 for SA, 0.3:1 for CA and SA, 1:1 for CMC and SA, and 0.3:1 for mixed matrices. The immobilised microalgae of mixed matrices exhibited the highest number of cells with 1.72 × 10 cells/mL at day 10 and 30.43% of oil extraction yield followed by CA and SA (24.29%), CMC and SA (13.00%), and SA (6.71%). Combining SA, CA, and CMC had formed a suitable structure which improved the growth of C. vulgaris and increased the lipid production compared to the immobilisation using single matrix. Besides, the fatty acids profile of the oil extracted indicates a high potential for biodiesel production.

Anaerobic digestion (AD) involves a series of biological processes in which organic material is broken down and transformed into biogas. A simulation model of the AD process in treating food waste to produce biogas was developed using Aspen Plus software. The components list, thermodynamic property package, reaction list, reactor model, and process condition were specified in Aspen Plus. Sensitivity analysis was performed to study the effect of hydraulic retention time and changes in food waste composition on the biogas production. The methane composition in biogas decreased when the hydraulic retention time was increased which is due to the reduction of substrate consumption during the AD process. The process model is able to represent the AD process and provides a good approximation on the production of biogas under various process operating conditions.

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Six resins (Amberlite XAD-16, Amberlite XAD-2, Sepabeads SP207, DIAION HP-20, DM11 and H103) were tested for vanillin adsorption in aqueous solution. All of the resins gave more than 95% adsorption rate except for Amberlite XAD-2 and DM11. Resin H103 was selected for the subsequent work due to its high adsorption capacity and low cost. A kinetic analysis revealed that the adsorption process followed pseudo-second-order kinetic model and occurred rapidly. The equilibrium point was reached after 90 minutes of reaction. Adsorption isotherm was also determined at 25 °C and it was fitted to Langmuir and Freundlich equations using linear regression and non-linear regression (sum of squares) methods. The regression shows that the adsorption of vanillin onto resin H103 followed Langmuir model (R 2 = 0.9984) with a maximum capacity of 73.015 mg/g. .my (S. Abd-Aziz).Note: The experiment was done in duplicates at 25 °C and 150 rpm (0.5 g resin, 100 ml of vanillin solution at 50 mg/l). The data were taken after 180 minutes of reaction.

The fiber morphology and elemental composition of pineapple leaf fibers were analyzed to understand their effect on the cellulose content and permittivity value. Cellulose fiber was extracted from pineapple leaf via the alkaline treatment method, and the content was determined using the Kurschner-Hanack method. The permittivity value of the developed cellulose fiber was measured based on the waveguide technique in the G-band. The surface morphology of the developed fiber was examined with scanning electron microscopy. Meanwhile, energy dispersive X-ray (EDX) spectroscopy was used to identify the elemental composition of the pineapple leaf fibers. The findings were that the cellulose fibers with the least diameter and distance between fibers exhibited the highest permittivity value, which was 1.85. The EDX analysis demonstrated that carbon was the commonest elemental in all fibers, and was 55 wt.% of the total element composition. Furthermore, the results showed that the permittivity value increased as the carbon composition increased, and decreased as the oxygen composition increased. Hence, the morphological and elemental studies of the cellulose fiber are useful in determining the permittivity value of the cellulose fiber for material development. The high permittivity value of the pineapple leaf fibers is believed to have great potential for use in electronic components.