Microalgae cells have the potential to rapidly accumulate lipids, such as triacylglycerides that contain fatty acids important for high value fatty acids (e.g., EPA and DHA) and/or biodiesel ...production. However, lipid extraction methods for microalgae cells are not well established, and there is currently no standard extraction method for the determination of the fatty acid content of microalgae. This has caused a few problems in microlagal biofuel research due to the bias derived from different extraction methods. Therefore, this study used several extraction methods for fatty acid analysis on marine microalga Tetraselmis sp. M8, aiming to assess the potential impact of different extractions on current microalgal lipid research. These methods included classical Bligh & Dyer lipid extraction, two other chemical extractions using different solvents and sonication, direct saponification and supercritical CO₂ extraction. Soxhlet-based extraction was used to weigh out the importance of solvent polarity in the algal oil extraction. Coupled with GC/MS, a Thermogravimetric Analyser was used to improve the quantification of microalgal lipid extractions. Among these extractions, significant differences were observed in both, extract yield and fatty acid composition. The supercritical extraction technique stood out most for effective extraction of microalgal lipids, especially for long chain unsaturated fatty acids. The results highlight the necessity for comparative analyses of microalgae fatty acids and careful choice and validation of analytical methodology in microalgal lipid research.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In the wake of intensive fossil fuel usage and CO2 accumulation in the environment, research is targeted towards sustainable alternate bioenergy that can suffice the growing need for fuel and also ...that leaves a minimal carbon footprint. Oil production from microalgae can potentially be carried out more efficiently, leaving a smaller footprint and without competing for arable land or biodiverse landscapes. However, current algae cultivation systems and lipid induction processes must be significantly improved and are threatened by contamination with other algae or algal grazers. To address this issue, we have developed an efficient two-stage cultivation system using the marine microalga Tetraselmis sp. M8. This hybrid system combines exponential biomass production in positive pressure air lift-driven bioreactors with a separate synchronized high-lipid induction phase in nutrient deplete open raceway ponds. A comparison to either bioreactor or open raceway pond cultivation system suggests that this process potentially leads to significantly higher productivity of algal lipids. Nutrients are only added to the closed bioreactors while open raceway ponds have turnovers of only a few days, thus reducing the issue of microalgal grazers.
Microalgae have been widely reported as a promising source of biofuels, mainly based on their high areal productivity of biomass and lipids as triacylglycerides and the possibility for cultivation on ...non-arable land. The isolation and selection of suitable strains that are robust and display high growth and lipid accumulation rates is an important prerequisite for their successful cultivation as a bioenergy source, a process that can be compared to the initial selection and domestication of agricultural crops. We developed standard protocols for the isolation and cultivation for a range of marine and brackish microalgae. By comparing growth rates and lipid productivity, we assessed the potential of subtropical coastal and brackish microalgae for the production of biodiesel and other oil-based bioproducts. This study identified Nannochloropsis sp., Dunaniella salina and new isolates of Chlorella sp. and Tetraselmis sp. as suitable candidates for a multiple-product algae crop. We conclude that subtropical coastal microalgae display a variety of fatty acid profiles that offer a wide scope for several oil-based bioproducts, including biodiesel and omega-3 fatty acids. A biorefinery approach for microalgae would make economical production more feasible but challenges remain for efficient harvesting and extraction processes for some species.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The presence of a sparse rain gauge network in complex terrain like the Himalayas has encouraged the present study for the concerned evaluation of Indian Meteorological Department (IMD) ground-based ...gridded rainfall data for highly prevalent events like cloudbursts over the northwest Himalayas (NWH). To facilitate the abovementioned task, we intend to evaluate the performance of these observations at 0.25° × 0.25° (latitude–longitude) resolution against a predefined threshold (i.e., 99.99th percentile), thereby initially comprehending the success of IMD data in capturing the cloudburst events reported in media during 2014–16. Further, seven high-resolution satellite products, namely, CMORPH V0.x, PERSIANN-CDR, TMPA 3B42RT V7, IMERG V06B, INSAT-3D multispectral rainfall (IMR), CHIRPS V.2, and PERSIANN-CCS are evaluated against the IMD dataset. The following are our main results. 1) Six out of 18 cloudburst events are detected using IMD gridded data. 2) The contingency statistics at the 99.99th percentile reveal that the probability of detection (POD) of TMPA varies from 19.4% to 53.9% over the geographical stretch of NWH, followed by PERSIANN-CDR (18.6%–48.4%) and IMERG (4.9%–17.8%). 3) A new metric proposed as improved POD (IPOD) has been developed in this work, which takes into account the temporal lag that exists between observed and satellite estimates during an event period. Results show that for an event analysis IPOD provides a better comparison. The IPOD for TMPA is 32.8%–74.4%, followed by PERSIANN-CDR (34.4%–69.11%) and IMERG (15.3%–39.0%). 4) The conclusion stands as precipitation estimates obtained from CHIRPS are most suitable for monitoring cloudburst events over NWH with IPOD of 60.5%–78.6%.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Cumulus convection clouds can produce a lot of rain in a short duration of time over a constrained area. Severe natural disasters like cloudbursts are regularly experienced as heavy rainfall events ...(HREs) in the North-West Himalayan region and during the Indian Summer Monsoon Rainfall season (June–September). These events cause significant losses in terms of life, infrastructure, crops, etc. Therefore, it is crucial to understand and predict such events in order to minimize costs. This study simulates an HRE that occurred in Mandi, India, on August 7, 2015, for a period of 24 h using the Weather Research and Forecasting (WRF) model, a numerical weather prediction system. To study the key elements of HRE, various cloud microphysics (CMP) methods are subjected to a sensitivity analysis. Ten CMP systems (CAM, Goddard, Lin, Milbrandt-Yau, Morrison, Thompson, WDM6, WSM3, WSM5, and WSM6) are taken into account in the sensitivity analysis. To ascertain how well the WRF model with each scheme represents such extreme localized heavy rainfall episodes, the model output is examined. The Indian Monsoon Data Assimilation and Analysis (IMDAA) reanalysis and the Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (GPMIMERG) Final run (V06B) satellite estimate datasets are used to create the observation proxies, which have horizontal resolutions of 12 km and 10 km, respectively. The output examination of the coarser and higher resolutions revealed that the WSM3 method performed very closely to the observation. Additionally, the bias in the simulated rainfall distributions of the Morrison and WSM3 schemes is evaluated for both domains; the WSM5 schemes showed the least error. Several meteorological variables that are connected to rainfall patterns, such as cloud fraction, maximum reflectivity, convective available potential energy, and wind flow field, are also thoroughly examined.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Mountainous regions are often faced with various challenges of monitoring and predicting accurate rainfall due to complex topography. Satellite precipitation estimates serve as rich repositories of ...data, which are highly valuable for varied applications. However, it is essential to prioritize satellite estimates based on their performance in capturing the weather patterns over mountainous terrains like Northwest Himalayas (NWH). The present study has spatially ranked five satellite estimates, namely, APHRODITE-V1901, CHIRPS-V2.0, CMORPH-V1.0, PERSIANN-CDR-V1, and TMPA-3B42-V7 against the Indian Meteorological Department observed data at 0.25° × 0.25° resolution over the period 1998–2018. An ensemble methodology that incorporates the ranking methods like GRA, MAUT, TOPSIS, and WASPAS and the statistical metrics is proposed. The analysis is based on precipitation indices such as consecutive wet days, R20mm, Rx1day, Rx5day, total precipitation, R95p, R99p, and SDII. The results show that, in order to monitor rainfall across the NWH region, APHRODITE-V1901 secured the first ranking, followed by PERSIANN-CDR-V1, while CHIRPS-V2.0 received the last rank. Further, NWH is divided into five regions, i.e., region I, region II, region III, region IV, and region V concerning elevation. The ensemble merged ranking method is applied in each of the classified regions. The results reveal that APHRODITE-V1901 secured the first rank in region II, CHIRPS-V2.0 in region IV, CMORPH-V1.0 in region I, PERSIANN-CDR-V1 in region V, and TMPA-3B42-V7 in region III. The analysis of the extreme rainfall events is performed towards the end using the best satellite estimates for the designated locations.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The main goal of this research is to assess the Indian Monsoon Data Assimilation and Analysis (IMDAA), a recently established high‐resolution (0.12° × 0.12°) reanalysis dataset, for observing ...cloudburst events over the Northwest Himalaya (NWH). In addition, a high‐resolution (0.1° × 0.1°) satellite estimate, the Integrated Multi‐satellitE Retrievals for Global Precipitation Measurement (GPM) version 6 (IMERG‐V06B) (Final run), is validated against the IMDAA. The following is a summary of our significant findings. (1) Reanalysis data from the IMDAA detects 11 out of 16 cloudburst incidences. In addition, 10 events captured in the IMERG‐V06B data are a subset of those captured by IMDAA. According to contingency measures, the probability of detection (POD) of IMERG‐V06B at 99.99th percentile is 33.33%–63.39% along the geographical extent of NWH. When utilizing the improved probability of detection (IPOD) to account for time, the possibility of IMERG‐V06B detecting cloudburst occurrences ranges from 41.24% to 68.25%. (2) According to the finding, the IMDAA accurately detects cloudburst events in Jammu and Kashmir (J&K), where data from the India Metrological Department (IMD) at a resolution of 0.25° × 0.25° have underperformed. As a result, we can deduce that IMDAA can be used to observe extreme events in the Himalayas. IMERG‐V06B is also relevant satellite data for monitoring cloudburst events and validating climate models.
Reanalysis IMDAA is evaluated for cloudbursts over NWH. Efficacy of high‐resolution satellite estimate IMERG‐V06B is tested for monitoring purposes. The study emphasizes the importance of evaluating both the IMDAA and the IMERG‐V06B satellite estimates, both of which have yet to be investigated across the NWH region, particularly for cloudburst events.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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•A superior collector for flotation of marine microalgae is identified.•Control of surfactant solubility is important for cationic flotation of microalgae.•The importance of froth ...stability in microalgae flotation is demonstrated.
Harvesting of oleaginous marine microalgae by dewatering is an important step for cost-effective algal biomass feedstock production. This paper reports separation of marine microalgae (Tetraselmis sp. M8) from aqueous medium by froth flotation using various collectors (surfactants) with equal carbon chain length, such as dodecyl pyridinium chloride (DPC), N-dodecylpropane-1,3-diamine hydrochloride (DN2), dodecyl amine hydrochloride (DAH), and sodium dodecyl sulphate (SDS), at different pHs. Algal hydrophobicity, froth stability, and surfactant precipitation were characterised. The laboratory-scale mechanical flotation tests showed that at natural pH 9.5 and a lower pH, DPC outperformed DAH, DN2 and SDS in separating Tetraselmis sp. M8 from seawater. DPC was capable of rendering the microalgae hydrophobic, producing metastable froth, and dissolving readily in water, which are all desirable features of a collector for flotation separation of microalgae from water. Use of DPC at 15ppm in pilot-scale Jameson cell flotation tests for M8 after outdoor cultivation led to a 23-fold increase in algal concentration with over 99% algal recovery.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Algal hydrophobicity and bubble size are key factors for microalgae flotation.•Algal hydrophobicity can be improved using cationic surfactants at appropriate pHs.•A step-wise optimization of algae ...flotation is demonstrated.
Microalgae harvesting by air flotation is a promising technology for large-scale production of biofuel, feed and nutraceuticals from algae. With an adherence-to-hydrocarbon method and two different types of flotation cells (mechanically agitated cell and Jameson cell), microalgal surface hydrophobicity and bubble size were identified to be critical for effective froth flotation of microalgae. Freshwater alga Chlorella sp. BR2 showed naturally a high hydrophobicity and an ideal response to flotation. However, many marine microalgae possess a low surface hydrophobicity and are thus difficult to harvest. This paper shows that a step-wise optimization approach can substantially improve the flotation of a low surface hydrophobicity marine microalga, Tetraselmis sp. M8, to near full recovery with an enrichment ratio of 11.4.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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