14 research outputs found
Pervaporation of Aqueous Ethanol Solutions Through Pure and Composite Cellulose Membranes
A procedure for synthesis of pure and composite membranes based on cellulose dissolved in NaOH-urea/ thiourea solutions was developed. The phase inversion method was employed for cellulose solution conversion to supported and non-supported membranes. The use of tetraethyl orthosilicate (TEOS) as precursor in synthesis of composite cellulose membranes produced significant changes in their structure and pervaporation behaviour. The obtained membranes were tested for the pervaporation of ethanol-water system. Pervaporation performances, which were evaluated in terms of total permeate flux, separation factor and pervaporation separation index, strongly depended on TEOS loading, ethanol concentration and operation temperature
Integrated System of Fed Batch ABE Biosynthesis and Solvent Recovery by Pervaporation
Anaerobic fermentation of glucose substrate by Clostridium acetobutylicum bacteria at 34-39 °C produces butanol, acetone, and ethanol solvents as metabolites. In the case of batch and fed batch bioreactors, the control of butanol concentration in the fermentation broth is recommended for diminishing its inhibitory effect on the bacterial system. Solvent recovery from batch or fed batch bioreactors by using an ultrafiltrationpervaporation system could be an efficient solution to improve the process performances. A mathematical model was developed in order to describe the dynamics of solvent production in an integrated system of fed batch fermentation and solvent recovery. Simulations performed under various operating conditions were used for optimizing the biosynthesis process, i.e., for maximizing the solvent production and minimizing the substrate concentration in the fermentation medium. Initial substrate concentration in the bioreactor, feed flow rate, feed substrate concentration, starting time of feed and ultrafiltration-pervaporation, surface area of ultrafiltration and pervaporation units were selected as process control variables
Synthetic aperture radar sensitivity to forest changes: A simulations-based study for the Romanian forests
Natural and anthropogenic disturbances pose a significant threat to forest condition. Continuous, reliable and accurate forest monitoring systems are needed to provide earlywarning of potential declines in forest condition. To address that need, state-of-the-art simulationsmodelswere used to evaluate the utility of C-, L- and P-band synthetic aperture radar (SAR) sensors within an integrated Earth-Observation monitoring system for beech, oak and coniferous forests in Romania. The electromagnetic simulations showed differentiated sensitivity to vegetation water content, leaf area index, and forest disturbance depending on SAR wavelength and forest structure. C-band data was largely influenced by foliage volume and therefore may be useful for monitoring defoliation. Changes in water content modulated the C-band signal by b1 dBwhichmay be insufficient for a meaningful retrieval of drought effects on forest. Cband sensitivity to significant clear-cuts was rather low (1.5 dB). More subtle effects such as selective logging or thinning may not be easily detected using C- or L-band data with the longer P-band needed for retrieving small intensity forest disturbances. Overall, the simulations emphasize that additional effort is needed to overcome current limitations arising from the use of a single frequency, acquisition time and geometry by tapping the advantages of dense time series, and by combining acquisitions from active and passive sensors. The simulation results may be applicable to forests outside of Romania since the forests types used in the study have similar morphological characteristics to forests elsewhere in Europe.Romanian National Agency for Scientific Research and Innovation Authorit
Effects of Marine Residue-Derived Fertilizers on Strawberry Growth, Nutrient Content, Fruit Yield and Quality
An outdoor experiment was performed for six months to evaluate the effects of organic fertilizers obtained from marine residual materials on strawberry plants. Three types of organic fertilizers were used, i.e., cod (Gadus morhua) bone powder, common ling (Molva molva) bone powder, and pellets obtained by mixing small cod bone powder and rockweed (Ascophyllum nodosum) residues. A tabletop system for strawberry cultivation was designed, in which two bare-root strawberry plants of cultivar ‘Albion’ were planted in a peat substrate in each pot. Five treatments were applied, i.e., cod bone powder (F1), common ling bone powder (F2), small cod bone powder and rockweed residue pellets (FA), chemical fertilizer (E), and a control (C). The number of leaves and their nutrient content, fruit yield and quality characteristics of the strawberries grown using the organic fertilizers were similar or better than those corresponding to treatments E and C. Organic fertilizers derived from the residues of fish and macroalgae could be a promising alternative to chemical fertilizers in strawberry production
EVALUATING CULTIVARS FOR ORGANIC FARMING: TOMATOES, PEPPERS AND AUBERGINE IN SOUTH ROMANIA
Organic farming has become a significant objective of the European Commission, and by 2030, EU member countries are required to find solutions to achieve the target of at least 25% of agricultural land being used for organic crops. As the area dedicated to organic farming continues to grow, there is a growing demand for cultivars that are optimized for this type of agricultural environment. Numerous studies have demonstrated that crop phenotypes can react differently when cultivated under different management systems, such as conventional versus organic. This has sparked a worldwide debate about whether we should develop cultivars exclusively for organic farming or if we can select suitable cultivars from conventional varieties for organic growing conditions. At the Vegetable Research Development Station Buzau, we have selected eleven cultivars of tomatoes (Siriana, Ema de Buzau, Flaviola, Ovidia, Hera, Andrada, Măriuca, Darsirius, Chihlimbar, Kristinica, Florina), five cultivars of peppers (Regal, Cantemir, A50, Roial, Decebal), and five cultivars of aubergine (Rebeca, Iarina, Romanița, H13Bz, H2Bz) that are typically suited for conventional farming. These cultivars were tested under organic farming conditions to investigate how genotypes interact in distinct growing systems and how this may impact yield and quality potential. Based on our study, we have drawn several conclusions. Darsirius has exhibited high ecological plasticity in both organic and conventional farming. Regal has shown uniform yields and fruits with high nutritional values in both growing systems. Rebeca has displayed tolerance to pest pathogens and has maintained stable yields under the studied systems. These findings are valuable for the ongoing efforts to develop cultivars that thrive in organic farming conditions and contribute to meeting the EU\u27s organic farming goals. Additionally, they shed light on the adaptability of specific cultivars to different agricultural systems and offer insights into maximizing yield and quality potential under organic cultivation practices
Retrieval of Forest Structural Parameters from Terrestrial Laser Scanning: A Romanian Case Study
Research Highlights: The present study case investigates the differences occurring when tree’s biophysical parameters are extracted through single and multiple scans. Scan sessions covered mountainous and hill regions of the Carpathian forests. Background and Objectives: We focused on analyzing stems, as a function of diameter at breast height (DBH) and the total height (H), at sample plot level for natural forests, with the purpose of assessing the potential for transitioning available methodology to field work in Romania. Materials and Methods: We performed single and multiple scans using a FARO Focus 3D X130 phase shift terrestrial laser scanner at 122 kpts and 0.3:0.15 mm noise compression ratio, resulting in an average point density of 6pts at 10m. The point cloud we obtained underpinned the DBH and heights analysis. In order to reach values similar to those measured in the field, we used both the original and the segmented point clouds, postprocessed in subsamples of different radii. Results: Pearson’s correlation coefficient above 0.8 for diameters showed high correlation with the field measurements. Diameter averages displayed differences within tolerances (0.02 m) for 10 out of 12 plots. Height analysis led to poorer results. For both acquisition methods, the values of the correlation coefficient peaked at 0.6. The initial hypothesis that trees positioned at a distance equivalent to their height can be measured more precise, was not valid; no increase in correlation strength was visible for either heights or diameters as the distance from scanner varied (r = 0.52). Conclusions: With regard to tree biophysical parameters extraction, the acquisition method has no major influence upon visible trees. We emphasize the term “visible”, as an increase in the number of acquisitions led to an increased number of detected trees (16% in old stands and 29% in young stands)