Comparison of mixed and plug flow reactor for enhancing the cell concentration of Haematococcus pluvialis growth

Photo bioreactions are employed for abating carbon dioxide emissions. The economics depends upon the choice of the type of the reactor. Photo bioreactions can be explained similarly to an autocatalytic reaction. A combined reactor mixed flow reactor followed by plug flow reactor could be the best choice. Using the data on cell concentration of Haematococcus pluvialis with respect to time in 2x concentration of Kobayashi’s basal medium available in the literature, it has been proved that the combined reactor could be the best choice. The optimum combination was also determined.

Numerical modeling of hydrogen-rich gas production from gasoline autothermal reforming in a plug flow reactor for electric vehicles

Due to the increase in the greenhouse effect, lowering emissions is becoming a certain issue all over the world. It is a concern to develop alternative options to minimize the spread of exhaust gases. For this purpose, in this study, the plug flow reactor in the system consisting of solid oxide fuel cell (SOFC), reactor, electric motor, battery, burner, and the heat exchanger is considered. Numerical modeling of hydrogen gas generation in a plug flow reactor is studied. The reactor indicated on-board hydrogen gas generation for an electric motor automobile has not been modeled in the literature yet. Autothermal reforming of isooctane is simulated in the COMSOL multi-physics software program in the reactor particularly. Conversion of isooctane and H2O are examined at different overall heat transfer coefficients, input temperatures, and steam/carbon ratios. Also, there are certain differences between adiabatic and non-adiabatic conditions. The produced synthesis gas of hydrogen drastically increases in the non-adiabatic case. The obtained results from the model are compared with experimental data obtained from the literature. H2 production at the end of the autothermal reforming process indicates the power provided from the reactor can operate a motor of an automobile. In the study, the achieved power is 65.8 kW (88 HP) is sufficient for an automobile. Simulation results show that the reactor volume of 75 L supplies 0.18 mols−1 of H2 and 0.08 mols−1 of CO in the non-adiabatic case.

Removal of Antibiotics and Nutrients by Vetiver Grass (Chrysopogon zizanioides) from a Plug Flow Reactor Based Constructed Wetland Model

Overuse of antibiotics has resulted in widespread contamination of the environment and triggered antibiotic resistance in pathogenic bacteria. Conventional wastewater treatment plants (WWTPs) are not equipped to remove antibiotics. Effluents from WWTPs are usually the primary source of antibiotics in aquatic environments. There is an urgent need for cost-effective, environment-friendly technologies to address this issue. Along with antibiotics, nutrients (nitrogen and phosphorus) are also present in conventional WWTP effluents at high concentrations, causing environmental problems like eutrophication. In this study, we tested vetiver grass in a plug flow reactor-based constructed wetland model in a greenhouse setup for removing antibiotics ciprofloxacin (CIP) and tetracycline (TTC), and nutrients, N and P, from secondary wastewater effluent. The constructed wetland was designed based on a previous batch reaction kinetics study and reached a steady-state in 7 days. The measured concentrations of antibiotics were generally consistent with the modeling predictions using first-order reaction kinetics. Vetiver grass significantly (p < 0.05) removed 93% and 97% of CIP and TTC (initial concentrations of 10 mg/L), simultaneously with 93% and 84% nitrogen and phosphorus, respectively. Results show that using vetiver grass in constructed wetlands could be a viable green technology for the removal of antibiotics and nutrients from wastewater.