This article presents an engineering study of an integrated system to produce bio-oil from microalgae biomass. The analysis is based on a pilot plant located at Minami-soma Fukushima, Japan, which further simulates 1 ha based-cultivation. Municipal wastewater and flue gases were utilized as nutrient sources for the microalgae culture of the proposed design. A flow sheet diagram of the integrated plant was synthesized by process engineering software to allow simulation of a continuous system. The design and sizing of the process equipment were performed to obtain a realistic estimation of possible production cost. The results demonstrated that nutrient savings was achieved by wastewater and CO₂ utilization to the polyculture of native microalgae. Process simulation gave an estimated CO₂ sequestration of 82.77 to 140.58 tons ha⁻¹year⁻¹ with 63 to 107 tons ha⁻¹year⁻¹ of potential biomass production. The integrated process significantly improved the energy balance and economics of biofuel production and also the wastewater treatment plant (WWTP). The economic analysis confirmed that higher biomass production and technology improvement were required to achieve operational feasibility and profitability of the current microalgae-based bio-oil production.

This study quantitatively analyzed the flow phenomena in model gastric contents induced by peristalsis using a human gastric flow simulator (GFS). Major functions of the GFS include gastric peristalsis simulation by controlled deformation of rubber walls and direct observation of inner flow through parallel transparent windows. For liquid gastric contents (water and starch syrup solutions), retropulsive flow against the direction of peristalsis was observed using both particle image velocimetry (PIV) and computational fluid dynamics (CFD). The maximum flow velocity was obtained in the region occluded by peristalsis. The maximum value was 9 mm s⁻¹ when the standard value of peristalsis speed in healthy adults (U_ACW = 2.5 mm s⁻¹) was applied. The intragastric flow-field was laminar with the maximum Reynolds number (Re = 125). The viscosity of liquid gastric contents hardly affected the maximum flow velocity in the applied range of this study (1 to 100 mPa s). These PIV results agreed well with the CFD results. The maximum shear rate in the liquid gastric contents was below 20 s⁻¹ at U_ACW = 2.5 mm s⁻¹. We also measured the flow-field in solid–liquid gastric contents containing model solid food particles (plastic beads). The direction of velocity vectors was influenced by the presence of the model solid food particle surface. The maximum flow velocity near the model solid food particles ranged from 8 to 10 mm s⁻¹ at U_ACW = 2.5 mm s⁻¹. The maximum shear rate around the model solid food particles was low, with a value of up to 20 s⁻¹.

This paper reports a novel formation method of monodisperse calcium alginate microbeads from water-in-oil-in-water (W/O/W) droplets with an ultra-thin oil phase layer. W/O/W droplets containing sodium alginate in an internal aqueous phase were formed as a template of calcium alginate microbeads using a microfluidic device. The ultra-thin oil phase layer of the W/O/W droplets was ruptured by an osmotic pressure difference between the internal and external aqueous phase. Immediately after the rupture, polyanionic alginate in the internal aqueous phase was cross-linked with calcium ion diffused from the external aqueous phase, and monodisperse and spherical calcium alginate microbeads were formed.