Search Results (3)

This study investigated a phototrophic approach to close nutrient loops by using landfill leachate as a culture medium to produce biomass and polyhydroxybutyrate (PHB) from a thermotolerant strain of Potamosiphon sp. A multi-cycle reuse scheme in which post-culture leachate was partially replenished with fresh leachate and reused in successive cultivation rounds to increase the biomass concentration (g/L) and the intracellular PHB content (% w/w) was tested. Three operational variables were optimized (leachate replenishment percentage, number of reuse cycles, and sanitation method (autoclaving, UV irradiation, or no treatment)) via the Box–Behnken response surface method. Both response variables were modeled with high predictive accuracy (R² = 0.98 for biomass and R² = 1.00 for PHB content). According to the experimental data, leachate replenishment emerged as the key factor influencing nutrient availability—particularly nitrogen and phosphorus—and thus PHB accumulation. The optimized conditions (2.17% v/v fresh leachate, three reuse cycles, and UV sanitation) yielded predicted values of 0.29 g/L biomass and 3.48% w/w PHB. These results demonstrate the feasibility of a controlled multicycle reuse process that integrates effluent treatment and biopolymer synthesis, offering a low-input, circular biotechnological approach for sustainable leachate valorization. Full article

The laser tube bending process (LTBP) process is a thermal non-contact process for bending tubes with less springback and less thinning of the tube. In this paper, the laser tube bending process will be studied experimentally. The length of irradiation and irradiation scheme are two main affecting process parameters in the LTBP process. For this purpose, different samples according to two main irradiation schemes (Circular irradiating scheme (CIS) and axial irradiating scheme (AIS)) and different lengths of laser beam irradiation (from 4.7 to 28.2 mm) are fabricated. The main bending angle of laser-bent tube, lateral bending angle, ovality, and thickness variations is measured experimentally, and the effects of the irradiating scheme and the length of irradiation are investigated. An 18 mm diameter, 1 mm thick mild steel tube was bent with 1100 Watts laser beam. The results show that for both irradiating schemes, by increasing the irradiating length of the main and lateral bending angle, the ovality and thickness variation ratio of the bent tube are increased. In addition, for a similar irradiating length, the main bending angle with AIS is considerably higher than CIS. The lateral bending angle by AIS is much less than the lateral bending angle with CIS. The results demonstrate that the ovality percentage and the thickness variation ratio for the laser-bent tube obtained by CIS are much more than the values associated with by AIS laser-bent tube. Full article

While the circular shape is currently the proven optimum design of the energy collection element (ECE) of a parabolic trough collector, that is yet to be confirmed for parabolic trough concentrating collectors (PTCCs) like trough concentrating photovoltaic collectors and hybrid photovoltaic/thermal collectors. Orientation scheme of the ECE is expected to have significant effect on the optical performance including the irradiance distribution around the ECE and the optical efficiency, and therefore, on the overall energy performance of the PTCC. However, little progress addressing this issue has been reported in the literature. In this study, a thorough investigation has been conducted to determine the effect of the orientation schemes of ECE on the optical performance of a PTCC applying a state-of-the-art Monte Carlo ray tracing (MCRT) technique. The orientation schemes considered are a flat rectangular target and a hollow circular, semi-circular, triangular, inverted triangular, rectangular and rectangle on semi-circle (RSc). The effect of ECE defocus, Sun tracking error and trough rim angle on the optical performance is also investigated. The MCRT study reveals that the ECE orientation schemes with a curved surface at the trough end showed much higher optical efficiency than those with a linear surface under ideal conditions. ECEs among the linear surface group, the inverted triangular orientation exhibited the highest optical efficiency, whereas the flat and triangular ones exhibited the lowest optical efficiency, and the rectangular one was in between them. In the event of defocus and tracking errors, a significant portion of the concentrated light was observed to be intercepted by the surfaces of the rectangular and RSc ECEs that are perpendicular to the trough aperture. This is an extended version of a published work by the current authors, which will help to design an optically efficient ECE for a parabolic trough concentrating collector. Full article