Iranian Journal of Chemical Engineering (IJChE)

Abstract This study simulated the production of bioethanol from mixed microalgae to the assess economic feasibility on an industrial scale. For the first time, the kinetic study of the chemical hydrolysis of mixed microalgae was carried out using the AQUASIM software. The chemical hydrolysis for the pretreatment of microalgae was carried out using H₂SO₄ (2.5%, 5%, 10% (v/v)), H₃PO₃ (2.5%, 5%, 10% (v/v)), and NaOH (1%, 2%, 4% (v/v)) at the different biomass concentrations (25 to 100 g/L) at the temperature of 121 ℃ for 70 min. Kinetic constants were calculated using experimental data and the AQUASIM software. It was found that the optimum yield of sugars, which was obtained, was about 93%. From the comparison of the values ​​of the reaction rate constant (k), it was observed that the hydrolysis rate ​​at 50 g/L by using H₂SO₄ 2.5% (v/v), is higher compared to 25, 75, and 100 g/L, and the higher reaction rate constant supports the faster hydrolysis of algal biomass. These kinetic constants were applied in simulating the process on an industrial scale using the SuperPro Designer software. Experimental and simulation results showed that 3.6 g/L of bioethanol is produced from the 9.3 g/L of glucose under optimal conditions. Also, simulation results using the SuperPro Designer software demonstrated that eliminating the algal biomass drying stage has the potential to save up to 713,000 $ in operational expenses.

Abstract In this work, performance of hollow fiber membrane photobioreactor (HFMPB) on the growth of Dunaliella Salina (G26) at various aeration rates (0.1 and 0.2 VVm) and medium re-circulation flow rates (500 and 1000 mL/h) were studied. Cultivation was carried out at both batch and semi-continuous modes in HFMPBs containing neat and hydrophilized in-house fabricated poly ethylene (PE) membranes at fixed light intensity of 300 µmol m-2 s-1and temperature of 30 oC. Microalgae showed better growth in hydrophobic module in both cultivation modes and modules. Maximum biomass concentration, CO2 biofixation and specific growth rates equal with 0.71g L-1, 1.102g L-1 d-1 and 0.224d-1 were obtained for non-wetted membranes, respectively. Comparing the performance of both modules showed that the impact of cultivation mode on the CO2 biofixation rate and CO2 removal is more pronounced than the impact of mass transfer resistance in membrane contactors. The obtained results show that the mean CO2 biofixation rates in semi-continuous cultivation for both neat and hydrophilized modules are higher than that in batch cultivation in all operating conditions. It was also found that the hydrophobic membranes are much preferable than hydrophilic membrane in HFMPBs.