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The influence of various solvents (H2O, CH3OH, and C2H5OH) on product distribution and nature of products during hydrothermal liquefaction of sargassum tenerrimum algae has been examined. Hydrothermal liquefaction was performed using H2O (260, 280 and 300°C) and organic solvents CH3OH and C2H5OH (280°C) for 15min. The use of organic solvents significantly increased the yield of bio-oil. In the case of liquefaction with CH3OH and C2H5OH, the bio-oil yield was 22.8 and 23.8wt.% respectively whereas the bio-oil yield was 16.33wt.% with H2O. GC-MS analysis of the liquid products indicated the presence of various organic compounds including aromatics, nitrogenated and oxygenated compounds and higher selectivity amount of ester compounds were observed in the presence of alcoholic solvents. NMR and FT-IR showed that present of solvents have an effect on the decomposition of sargassum tenerrimum algae.

Nitrogen reduction reaction (NRR) and nitrate reduction reaction (NO3−RR) provide a potential sustainable route by which to produce ammonia, a next-generation energy carrier. Many studies have been conducted over the years, mainly emphasizing material design and strategies to improve catalytic performance. Despite significant achievements in material design and corresponding fundamental knowledge, the produced ammonia is still very limited, which makes it prone to bias. The presence of interferants (e.g., cations and sacrificial reagents), the pH of the solution, and improper analytical procedure can lead to the over or underestimation of ammonia quantification. Therefore, the selection of the appropriate ammonia quantification method, which meets the sample solution condition, along with the proper analytical procedures, is of great importance. In this review, the state-of-the-art ammonia quantification method is summarized, emphasizing the advantages, limitations, and practicality for NRR and NO3−RR studies. Fundamental knowledge of the quantification method is introduced. Perspective on the considerations for selecting the suitable quantification method and for performing the quantification process is also provided. Although non exhaustive, this focused review can be useful as a guide to design the experimental setup and procedure for more reliable ammonia quantification results.

Climate change affects the timing of phenological events, such as the start, end, and length of the growing season of vegetation. A better understanding of how the phenology responded to climatic determinants is important in order to better anticipate future climate-ecosystem interactions. We examined the changes of three phenological events for the Mongolian Plateau and their climatic determinants. To do so, we derived three phenological metrics from remotely sensed vegetation indices and associated these with climate data for the period of 1982 to 2011. The results suggested that the start of the growing season advanced by 0.10 days yr-1, the end was delayed by 0.11 days yr-1, and the length of the growing season expanded by 6.3 days during the period from 1982 to 2011. The delayed end and extended length of the growing season were observed consistently in grassland, forest, and shrubland, while the earlier start was only observed in grassland. Partial correlation analysis between the phenological events and the climate variables revealed that higher temperature was associated with an earlier start of the growing season, and both temperature and precipitation contributed to the later ending. Overall, our findings suggest that climate change will substantially alter the vegetation phenology in the grasslands of the Mongolian Plateau, and likely also in biomes with similar environmental conditions, such as other semi-arid steppe regions.

The Western Rajasthan commonly known as the ‘Indian Thar Desert’ is characterised by harsh climatic conditions with active dunal activities. Precipitation (150–420 mm/yr) is far lower than evapotranspiration potentials (1500–2000 mm/yr). Ground water is limited and often brakish and high (75–100 m) water table. Solar intensity in the region varies from 5.85 to 6.44 kWh/m2/day. Further, peculiarity of the region is that sun is available for 345–355 days in a year, the area being highly scarce in rainfall. On an average, rains occur only for 10.4–20.5 days in a year in the Thar Desert. Therefore, there is high scope to harness solar energy for useful purposes. Considering these solar energy technologies for entrepreneurs, the detailed cost analysis has been worked out and presented. With initial investment of Rs (Indian Rupees) 3.50 lakhs for solar drying projects for handling 60,000 kg fresh vegetables annually (300 working days/yr), the payback period and average net annual returns come to 2.17 years and ...

Abstract Whilst caking occurs via several different mechanisms, absorption and migration of moisture is frequently the most dominant mechanism within the food and pharmaceutical industry. Fully understanding the propensity to cake is important for minimising down-stream process issues, however most characterisation techniques assume that moisture induced caking occurs homogenously through the sample resulting in a uniformly caked powder bed. In this study, the effect of moisture induced caking on powder flowability was investigated using powder rheology. Several materials, including skimmed milk powder (SMP) and sulphated methyl ester (SME) were stored for several days under controlled humidity conditions. The flow energies, a measure of the resistance to flow, were measured at 24 h intervals using an FT4 Powder Rheometer. As the energy is measured as a function of the bed height, variations in the powder bed are also captured. The results demonstrated that caking does not always occur uniformly, instead a caked region (or crust) forms at the air-powder interface and then progresses through the powder bed. Furthermore, the strength of this caked region was shown to increase over several days before stabilising.

Lipid productivity of microalgae depends considerably on the method of its cultivation. In the present study, a two-stage culture strategy was conducted to cultivate Chlorella vulgaris to enhance lipid productivity. In the first stage, C. vulgaris was grown in the synthetic medium to obtain maximum biomass concentration. Wastewater is used as a medium for growing microalgae to have commercial and environmental aptitudes for biomass production. The nutrient removal efficiencies were 80.5% (COD), 70% (TN), and 78% (TP). In the second stage, the synergistic effects of nitrogen and NaCl concentration on the lipid productivity was investigated by response surface methodology (RSM) for 2 days. The optimum conditions for relatively high lipid productivity (up to 80 mg L−1 day−1) were 2.6 mg L−1 of nitrogen, 6.3 g L−1 of NaCl, and 4.9 g L−1 of biomass concentration. The value which was predicted by model was in good agreement with the experimental value, as it was determined by the validation experiments. Saturated fatty acid composition was increased by 27.3% under optimized medium compared with synthetic medium, which is very suitable for biodiesel production. According to the above results, it is concluded that the combination of multiple stress conditions can lead to a cost-effective technology of microalgae lipid production.

Anode with good electrocatalytic capabilities is more specifically required to reduce the ohimic losses during microbial fuel cell (MFC) operation. Highly conductive polymers viz., Polyaniline (PANi) and Polyaniline/Carbon nanotube (PANi/CNT) composite were prepared by in situ oxidative chemical polymerization method. Anodes were fabricated independently by coating PANi and CNT/PANi composites on the surface of SSM. The fabricated electrodes were evaluated as anode against stainless steel mess (SSM) as cathode during MFC operation. Maximum bioelectricity generation was observed in SSM-PANi/CNT-anode with power density of 48 mW/m2 and COD removal efficiency of 80% compared with SSM-PANi-anode (38 mW/m2; 65%) and SSM-anode (28 mW/m2; 58%). Bioelectrochemical characterization of the electrode materials using cyclic voltammetry and electrochemical impedance spectroscopy showed high electrocatalytic activity of PANi/CNT composite electrode. The study concluded the efficiency of PANi/CNT composite electrodes as bioanode in operation of MFCs towards achieving increased bioelectricity production along with wastewater treatment.

A promising route to transition wastewater treatment facilities (WWTFs) from energy-consuming to net energy-positive is to retrofit existing facilities with process modifications, residual biosolid upcycling, and effluent thermal energy recovery. This study assesses the economics and life cycle environmental impacts of three proposed retrofits of WWTFs that consider thermochemical conversion technologies, namely, hydrothermal liquefaction, slow pyrolysis, and fast pyrolysis, along with advanced bioreactors. The results are in turn compared to the reference design, showing the retrofitting design with hydrothermal liquefaction, and an up-flow anaerobic sludge blanket has the highest net present value (NPV) of $177.36MM over a 20-year plant lifetime despite 15% higher annual production costs than the reference design. According to the ReCiPe method, chlorination is identified as the major contributor for most impact categories in all cases. There are several uncertainties embedded in the techno-economic analysis and life cycle assessment, including the discount rate, capital investment, sewer rate, and prices of main products; among which, the price of biochar presents the widest variation from $50 to $1900/t. Sensitivity analyses reveal that the variation of discount rates causes the most significant changes in NPVs. The impact of the biochar price is more pronounced in the slow pyrolysis-based pathway compared to the fast pyrolysis since biochar is the main product of slow pyrolysis.