Parisa A. Bahri

Optimizing photobioreactor (PBR) design is essential for improving the productivity and energy efficiency of microalgal cultivation systems. This study employed Computational Fluid Dynamics (CFD) simulations to assess the hydrodynamic performance of an inclined flat plate PBR for Arthrospira platensis cultivation. The CFD model, validated against experimental data (maximum discrepancy: 8.4 %, R2 = 0.81), reliably predicted biomass productivity and internal flow dynamics. Five sparger configurations and four aeration rates were investigated for their effects on radial velocity, turbulence kinetic energy (TKE), and dead zone formation.

The results highlighted the hydrodynamic advantages of the rear-most sparger position (R). At 0.21 vvm (volume of air per volume of culture per minute), position R achieved a radial velocity of 0.125 m·s−1, a TKE of 4.32 × 10−3 m2·s−2, and a dead zone fraction of 18.23 %, closely matching the middle sparger position at 0.23 vvm. Notably, 0.23 vvm represented the highest tolerable aeration rate experimentally, as exceeding this threshold induced shear-related mechanical stress, negatively impacting microalgal cell integrity and reducing productivity. Thus, sparger position R provided equivalent mixing at reduced aeration, lowering energy demand and operational stress.

The inclined geometry enhanced flow uniformity and turbulence, particularly with rearward sparger placement. Integrating dead zone analysis with velocity and TKE metrics, this study offers a validated framework for optimizing sparger design in inclined flat plate PBRs. These findings have significant implications for improving energy efficiency and scalability in laboratory and industrial scale microalgal cultivation systems.

The microalgae Botryococcus braunii holds significant promise for biofuel generation. This study delves into an innovative B. braunii biofilm cultivation approach to trim energy consumption as well as harvesting costs. The investigation encompassed two distinct processes, i.e., algae turf scrubber (ATS) biofilm and open raceway pond (ORP) systems. The simulation of integrated cultivation, harvesting, and lipid extraction processes was conducted using SuperPro Designer. Furthermore, capital and operational expenses were calculated to be further discussed in terms of techno-economics and profitability. The ATS biofilm reached a notably high biomass productivity of 38 g m− 2 d− 1 when compared to the ORP system (7.5 g m− 2 d− 1). Likewise, the ATS biofilm cultivation demonstrated lesser water consumption by up to 6-fold and facilitated a remarkable 77.3% reduction in total OPEX. Besides, the microalgae cultivation plant using the ATS biofilm system with a lifetime of 12 years leads to an IRR of up to 26.43% with a DPBP of 5.9 y if the biofuel product is sold at 3.7 USD L− 1. Given this potential, biofuel production from B. braunii in the ATS biofilm system can be an attractive option in terms of process reliance and feasibility for future large- and commercial-scale microalgae industries.

Pig face detection plays a crucial role in the field of agricultural farming, especially in precise feeding and disease monitoring. This study proposes a method called adaptive region-based convolutional neural network (A-RCNN) for multiangled dirty pig face detection in outdoor environments. First, in order to address the interference caused by dirty cleaning surfaces, a feature enhancement module (FEM) is designed to improve the network's classification ability. Second, in order to ensure that the anchor points are more in line with the shape of the pig surface, an anchor point selection module (APSM) is introduced to generate high-quality area recommendations. Finally, in response to the interference problem of complex outdoor backgrounds, this article adopts a dynamic training strategy (DTS) to optimize the final detection results using these high-quality region suggestions. This study conducted an in-depth exploration of the publicly available JD dataset, and the experimental results showed that compared with existing methods, this method demonstrated excellent performance, achieving 56.3% mean average precision (mAP) and an improvement of 6.02% compared to the baseline Faster RCNN. In addition, to verify the practical application effect of the model, this article also deployed it on the edge device Raspberry Pi 4B, further confirming the effectiveness and practicality of the model.

Given the urgent need to decarbonise the transport sector, a comprehensive analysis of alternative fuel technologies is essential. This study introduces an innovative freight transport model, incorporating a novel approach to calculating vehicle time costs, refuelling time, and energy intensity, applied to Australia’s freight sector. Findings indicate that under moderate development, battery electric vehicles gain a larger share in light commercial vehicles, while fuel cell electric vehicles dominate the truck segment. In high development scenarios, battery electric and fuel cell electric vehicles achieve closer parity across all vehicle types. The transition impacts refuelling infrastructure, with significant shifts in petrol and diesel station numbers, posing potential investment risks for diesel stations due to fluctuating demand across scenarios. High development scenarios highlight a substantial need for investment, driven by a surge in hydrogen station requirements and battery electric vehicle charger demand peaking at approximately 120,000 units in the internal combustion engine-ban scenario. Emission trends vary by scenario. Under reference and moderate development scenarios, total tank-to-wheel and well-to-wheel emissions increase over time. However, the internal combustion engine-ban and comprehensive scenarios lead to substantial emission reductions, underscoring the environmental significance of policy choices and technological advancements.

Arthrospira platensis has been a dietary staple for decades. While raceway ponds are commonly used for mass cultivation, closed photobioreactors (PBRs) offer higher productivity and reduced contamination risks. Mixing rate is a critical factor influencing microalgal growth and productivity. This study examines the impact of air injection flow rates (0.17–0.27 vvm), corresponding to superficial gas velocities of 0.00315–0.0050 m·s−1, on the growth, productivity, and effective quantum yield (f'q/f'm) of A. platensis in a 140 L self-cooling flat plate PBR with an infrared-reflective thin-film coating that enables passive temperature control and reduces energy demand for cooling.

The optimal gas velocity of 0.00389 m·s−1 yielded an average productivity of 0.126 g·L−1·d−1. Beyond this velocity, at 0.00426 m·s−1, there was neither significant increase in productivity, nor a notable decrease in f'q/f'm. However, at higher gas velocities of 0.00463 m·s−1 and 0.0050 m·s−1, f'q/f'm decreased significantly, by up to 48.6 %, indicating adverse effects on the microalgal cells. Lower velocities (<0.00389 m·s−1) did not affect f'q/f'm but resulted in inadequate mixing, reducing biomass productivity by 16.4 % and 23.8 % for 0.00352 and 0.00315 m·s−1.

A validated growth model accurately predicted A. platensis growth (R2 = 94.5 % for biomass, 81.2 % for temperature). Moreover, Experimental data from Perth, Australia, during spring and winter aligned closely with model predictions. This integration of experimental data and predictive modelling highlights the importance of precise mixing rate optimization in maximizing microalgal productivity and demonstrates the reliability of such models for advancing large-scale algal cultivation.
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Despite their vulnerability to climate change, mining and refining industries significantly provide energy transition materials. However, if no mitigation is implemented, the demand growth will increase direct and indirect emissions in the critical mineral sector. This research aims to comprehensively evaluate the decarbonisation agenda in lithium, nickel, and cobalt industries by profoundly examining the performances, strategies, and risks associated with climate transition. This study examines company reports of 27 players that accounted for at least half of the global lithium, nickel, and cobalt production. This study uses content analysis methodology to reveal patterns in decarbonisation targets, performances and practices. More than two-thirds of the observed companies favour onsite solar and wind generation. At least one-third of the samples mention energy-efficient equipment and electric vehicle adoption. Despite having a well-crafted strategy to reduce operational emissions, more efforts are needed to reduce the value-chain emissions. This study highlights the need for improvement in the carbon inventory and disclosure of scope three emissions by utilising artificial intelligence and maintaining strategic partnerships with stakeholders. Political, economic, social, technological, legal, and environmental (PESTLE) analysis also revealed patterns and linkages among the current decarbonisation challenges and opportunities, of which the industries are vulnerable to demand fluctuation, rising from regulatory and technological changes. This study highlights the current dynamics in the critical mineral supply chain, which may affect decarbonisation strategies in the industry. This study also provides a holistic approach to offer empirical practice for the industries, allowing them to tailor their strategies.

Microalgae present significant advantages as renewable feedstocks with applications spanning food and nutraceuticals, cosmetics, and pharmaceuticals. Microalgae can be used for food supplements, animal feed, fertilizers, biofuels, and bioplastics. However, large-scale utilization is constrained by the lack of sustainable harvesting systems, as harvesting remains the primary bottleneck in terms of both energy demand and economic sustainability. Conventional harvesting methods face limitations in terms of cost, scalability, and applicability. Thus, there is a growing need for low-cost, robust, eco-friendly, and highly efficient dewatering strategies. Magnetite nanoparticles (MNPs) have recently gained considerable attention for microalgal harvesting owing to their large surface-to-volume ratio, high recovery efficiency, time-saving separation, and potential for reuse. MNPs remain stable in suspension and can be easily recovered by applying an external magnetic field, making them a promising option for enhancing both harvesting and dewatering processes. Although magnetic harvesting and dewatering have emerged as promising alternatives to conventional methods, several challenges remain, particularly concerning the recovery, reuse, and overall cost of magnetite nanoparticles (MNPs). Among these, the most critical hurdle is achieving efficient detachment and repeated reuse of MNPs. This review critically evaluates the potential of MNPs for microalgae harvesting, with emphasis on strategies to enhance their stability, harvesting efficiency, economic sustainability, recoverability, and reusability. Current advancements and future perspectives of this technology are also discussed. Furthermore, various approaches for recovering MNPs are examined, focusing on their effectiveness, limitations, and long-term sustainability for industrial scale microalgal harvesting.

The possibility of using microalgae to assimilate nitrogen from agricultural anaerobic digestion effluents (ADE) not only has environmental benefits but also can result in making profit from ADE by converting microalgae to value added products. Here, a techno economic model was developed to study the possibility of producing oil and amino acid concentrate products from microalgae grown on ADE. The results show that it would be possible to produce 14 L biostimulant (amino acid concentrate), 198 g refined oil, and 57 g omega 3 isolate from 1 m3 ADE using microalgae with possible production cost of 0.9 – 2.1 AUD L−1, 86 – 120 AUD kg−1, and 700 – 730 AUD kg−1 respectively depending on the scale. The profitability results at the scale of 500 to 3,000 m3 d−1 ADE capacity indicate that the production of biostimulant, refined oil, and omega 3 isolate products from wastewater grown microalgae can lead to 4 – 15, 6 – 9, and 5 AUD m−3 net profit respectively.

There has been a conversation about developing electric vehicle industries in Indonesia and Australia. While many studies have identified the barriers and opportunities for developing the industry, limited studies have been conducted to estimate the demand and supply of critical minerals to produce electric vehicle batteries, particularly in Indonesia. This study investigates the future demand for lithium, nickel, and cobalt in Indonesia and Australia by considering multiple scenarios and technological options. The study highlights the importance of circular economic intervention, such as material substitution and recycling, to ensure a sustainable supply of these minerals. The result shows that the lithium, nickel, and cobalt reserves will be adequate for developing the domestic electric vehicle industry in Australia. The domestic production will consume between 0.4 per cent and 4.5 per cent of the available reserve. In Indonesia, domestic production will consume up to 1.2 per cent of the available nickel reserve. However, it will consume more than a quarter of cobalt reserve in a scenario where high-nickel cathode dominates the market. Indonesia might also need to import lithium. Therefore, the result emphasises the need to foster bilateral cooperation between Indonesia and Australia to develop a secure and resilient electric vehicle industry in the region. The study concludes that a multifaceted approach, including technological and policy advancement in sustainable consumption and production practices, is essential to mitigate climate change in these countries.

Developing more efficient microalgal photobioreactors (closed cultivation systems) is impelled by increasing interest in microalgal cultivation to produce high-value products. Compared to open cultivation systems closed photobioreactors (PBRs) offer several advantages, including the potential for high productivity in a small footprint, ability to maintain a controlled environment, and their scalability for commercial production. Computational Fluid Dynamics (CFD) provides a powerful tool to simulate flow conditions of microalgal cultivation systems and analyze operational parameters which may affect cultivation key factors such as light (wavelength, intensity, and period of exposure), accessibility to nutrients, and mixing. Besides, geometric modifications employing CFD can accelerate the design process and considerably reduce the need for a thorough, empirical exploration of reactor configurations and the associated costs. This paper provides a comprehensive review of recent updates on the application of CFD in various microalgal cultivation systems with special focus on different geometry optimization of flat plate photobioreactors.

This review examines recent studies that have employed various multiphase and turbulence methods within the CFD framework to simulate fluid flow and turbulence within reactors, aiming to improve flow characteristics and enhance microalgal productivity. Specifically, the application of CFD in optimizing flat plate photobioreactors is explored, with researchers investigating a range of baffles and sparger configurations to enhance microalgal productivity. Additionally, the advantages of adopting CFD are discussed, and the potential future applications of CFD in microalgal cultivation are outlined.