Utilization of renewable energies in association with energy storage is increased in different applications such as electrical vehicles (EVs), electric boats (EBs), and smart grids. A robust controller strategy plays a significant role to optimally utilize the energy resources available in a power system. In this paper, a suitable controller for the energy resources of an EB which consists of a 5 kW solar power plant, 5 kW fuel cell, and 2 kW battery package is designed based on the linear parameter varying (LPV) controller design approach. Initially, all component dynamics are augmented, and by exploiting the sector-nonlinearity approach, the LPV representation is derived. Then, the LPV control method determines the suitable gains of the states’ feedbacks to provide the required pulse commands of the boost converters of the energy resources to regulate the DC-link voltage and supply the power of EB loads. Comparing with the state-of-the-art nonlinear control methods, the developed control approach assures the stability of the overall system, as it considers all component dynamics in the design procedure. The real-time simulation results demonstrate the performance of the designed controller in the creation of a constant DC-link voltage.

To avoid pollution of transportation applications, renewable energies are deployed. Whereas they are uncontrolled, fully controlled pollution-free energy sources and storage units should be also considered. However, a complicated direct current (DC) microgrid (MG) is obtained, which suffers from nonlinearities, high order, and uncertainties of the power elements. Therefore, it is vital to use advanced nonlinear controllers to assure closed-loop stability and performance of the overall system. In this paper, a neural network (NN)-based adaptive linear parameter varying (LPV) controller is suggested for the whole DC MG power system. The main advantage of the developed controller is that it deploys the operating information of all power energy sources to manipulate each component. This enhances the DC MG stability margin and fast regulation of the power and voltage. Besides, the proposed controller has a systematic and fully offline design algorithm by combining numerical solvers and theoretical theories. The LPV controller is designed via the numerical linear matrix inequality (LMI) approach and the adaptation law for the NN parameters is designed based on the Lyapunov stability theory. A DC MG benchmark including a 5kW fuel cell, a 5kW solar plant, and a 2kW battery package is considered as the case study, which can be utilized in future fully electric boats (EBs). Numerical simulations with different scenarios are conducted to verify the performance of the proposed controller. Furthermore, comparative results are provided to show the advantages of the proposed method dealing with power fluctuations of the solar plant and DC loads over state-of-the-art nonlinear methods.

Light is one of the most critical factors for the growth of microalgae; therefore, optimization and accessibility of light improve productivity and wastewater nutrient removal is important. The flashing light effect allows microalgae to use light effectively through intermittent exposure. Nutrient assimilation and membrane fouling were considered in a reciprocal membrane photobioreactor (RMPBR) and an LED flashing light was provided as a source of illumination. The objective of this study was to bridge the gap between light delivery and RMPBR performance. In this connection, we examined flashing lights with frequencies of 1 Hz and 1000 Hz at a constant duty cycle of 60% along with continuous light. Regarding the effect of the flashing light on RMPBR, the cells which acclimated to flashing light of 1000 Hz resulted in maximum removal of nitrate (97%) and phosphate (70%). However, the culture with the low frequency of 1 Hz was only able to remove nitrate and phosphate up to 68% and 47%, respectively. Furthermore, the reactor with 1-Hz flashing light frequency was fouled earlier within 84 h thereby reaching the highest pore-blocking. Proteins and carbohydrates were recognized as a major cause of fouling in the lowfrequency flashing light. We conclude that high-frequency flashing light (1000 Hz) could be an effective light condition for nutrient uptake in wastewater treatment.

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The membrane photobioreactor (MPBR) is a well‐operated system concerning microalgae cultivation and nutrients assimilation from wastewater effluent. In the present paper, a sample of pulp and paper wastewater was primarily treated by activated sludge system (ACS), and the concentration of nitrate and phosphate decreased as about 26 and 10%, respectively. Then, it was transferred into six flat plate MPBR systems with 5 L capacity and 0.45 μm membrane pore size for the secondary treatment process (nitrate and phosphate assimilation) by Chlorella vulgaris (green microalgae) species during six cultivation periods. In this section, the effects of different light intensities (100 and 300 μmol m−2 s−1) and light–dark cycles (24–0, 16–8, and 12–12) on nitrate and phosphate uptake through the treated pulp and paper wastewater effluent after 24 hr were investigated. The maximum photosynthetic productivity and nitrate‐phosphate removals after 24 hr (nitrate: 57% and phosphate: 43%) were recorded for the culture under 300 μmol m−2 s−1 and 24–0 light–dark regime within the MPBR system.

BACKGROUNDThe membrane photobioreactor is a combination of membrane technology and the photobioreactor system. It is an economic and efficient system for microalgae cultivation. Light cycles and its intensity are significant parameters in the biomass production and synthesis of metabolites, such as protein and carbohydrates, within the microalgae cells. These parameters can, therefore, have a significant impact on the rate and characteristics of fouling in membrane photobioreactor systems.RESULTSIn this work, Chlorella vulgaris (green microalgae) was cultivated within the designed reciprocal membrane photobioreactor (RMPBR) under 24–0, 16–8, and 12–12 light–dark (L/D) cycles. Also, the transmembrane pressure (TMP) and different hydraulic membrane resistances (cake layer, pore‐blocking, and fluid resistances) were investigated. The 16–8 L/D cycle had the fastest fouling time (96 h), highest pore‐blocking resistance (Rp), and the maximum concentrations of protein and carbohydrate in the supernatant and permeate flux. However, the 12–12 L/D recorded the maximum cake layer resistance (Rc), the highest content of protein within the cake layer, and the longest fouling time (226 h). Additionally, the highest carbohydrate concentration within the cake layer was for the 24–0 L/D regime, and it was fouled after 162 h.CONCLUSIONThe Rc for each cycle had the highest values compared to the other calculated resistances. When the membrane is fouled, the mechanical membrane cleaning method employed in the RMPBR, which is in the form of an automatic spongy blade, cleans the cake layer on the membrane and improves its operation up to 80% via decreasing the Rt of the system. © 2020 Society of Chemical Industry (SCI)

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The use of membranes is widely common in bioprocess industry to separate constituents of a liquid, especially during cell clarification process. Many has opted for normal flow filtration mode for this process due to the ease of handling of this technique as compared to tangential flow filtration. Meanwhile, antifoams are chemicals used in upstream process to eliminate the formation of foam throughout the course. It is normally used in conjunction with a nutrient rich broth that is used as a media to cultivate the cells. Some has claimed that antifoam may lead to premature membrane fouling, but some reported that the presence of antifoam may assist and improve the flux rate of the filtration process. This study investigates the effects of organic antifoam presence in a cell-free media on the performance of the filtration process, specifically normal flow filtration process. It was discovered that the presence of organic antifoam may be significant at 1.0% concentration of antifoam loaded in the sample which gives filtration capacity of 250L/m2 while filtration capacity was reported to be at 330L/m2 for samples containing 0.2% and 0.6% antifoam concentration. The flux rate profile has lower percentage reduction that ranges from 18% to 33% which resulted to final flux rate of approximately 700 – 800LMH for initial flux rate of 1000LMH and 27% to 46% reduction that lead to final flux rate of approximately 1000 – 1500 LMH for initial flux rate of 2000LMH.