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Adsorption capacity of the biochar obtained from Pinus patula wood micro-gasification for the treatment of polluted water containing malachite green dye

Rubio Clemente, Ainhoa | 2021

In this work, the adsorption capacity of the biochar obtained from Pinus patula biomass micro-gasification was studied using malachite green (MG) as the probe pollutant. For this purpose, the biomass type (wood pellets and chips) was selected to produce two kinds of biochar (BC). Afterwards, the effects of the adsor- bent dose (6, 9 and 12 g/L), the solution pH (4, 7 and 10) and the BC particle size distribution (150–300, 300–450 and 450–600 lm) for the maximization of the MG retention by the selected BC were evaluated using a faced-centered central composite design, as response surface methodology. The results indicated that the BC derived from wood chips (BWC) exhibited a higher MG dye adsorption capacity than the BC obtained from the wood pellets (BWP) gasification under the same operating conditions after having reached the equilibrium. A second-order regression model was built for describing the MG adsorption behaviour by BWC under the considered experimental domain. The model, which was validated, resulted to be statistically significant and suitable to represent the MG adsorption by the studied BC with a p- value of 0.00 and a correlation coefficient (R2) of 95.59%. Additionally, a three-dimensional response sur- face graph and a contour plot were utilized to analyze the interaction effects between the factors influ- encing the adsorption system and to discern the optimal operating conditions for the use of BWC. The maximal MG dye retention (99.70%) was found to be at an adsorbent dose, pH solution and a particle size distribution of 9.80 g/L, 10 and from 150 to 300 lm, respectively. Therefore, the BWC tested can be uti- lized for the treatment of water polluted with dyes, contributing to the establishment of a circular economy.

Numerical and experimental study of hydrofoil-flap arrangements for hydrokinetic turbine applications

Aguilar Bedoya, Jonathan | 2021

In this work, the efficiency of two horizontal-axis hydrokinetic turbines, whose blades were designed with and without multi-element hydrofoil cross-sections, has been numerical and experimentally inves- tigated for tip speed ratio (k) values ranging between 2.5 and 9.0 to compare the experimental rotor per- formance with numerical results. The Eppler 420 hydrofoil was used for the design of the blades applying the blade element momentum (BEM) theory. The variation of the power coefficient curve of the turbines was analyzed by using computational fluid dynamics (CFD) and experimental tests through ANSYs Fluent software with six-degrees of freedom (6-DoF) user-defined function (UDF) method and an open hydraulic channel, respectively. Numerically, for the turbine with a multi-element hydrofoil and without a multi- element (traditional) hydrofoil, maximum power coefficients (CPmax) of 0.5050 and 0.419 (at a k value equal to 7.129 and 6.739, respectively) were obtained. It is worth noting that a reasonable agreement between the numerical and the experimental results was achieved. In this regard, the blade with a multi-element hydrofoil has a positive influence on the hydrokinetic turbine performance; therefore, it can be used for power generation in river or marine systems.

Assessment of the application of two amendments (lime and biochar) on the acidification and bioavailability of Ni in a Ni-contaminated agricultural soils of northern Colombia

Becerra Agudelo, Evelyn | 2022

Soil acidification and increased bioavailability of Ni are problems that affect agricultural soils. This study aims to compare the effects of both lime and biochar from corn stover in soil acidity correction, improving soil physicochemical properties and soil re-acidification resistance. As well as assesseing the impacts on human health risk caused by bioavailability of nickel. A greenhouse pot experiment was conducted for 30 days to determine the effect of biochar and lime on soil physicochemical properties and nickel bioavailability. Afterwards, a laboratory test was carried out to determine the repercussions of both amendments on soil resistance to re-acidification and re-mobilization of nickel. Human health risk was determined using nickle bioavailable concentration. Overall, the results of this study showed that biochar application significantly reduced soil acidity from 8.2 ± 0.8 meq 100 g−1 to 1.9 ± 0.3 meq 100 g−1, this reduction markedly influenced the bioavailability of nickel, which decreased significantly. Moreover, soil physicochemical properties and soil resistance to acidification were improved. Furthermore, biochar significantly reduced human health risk compared to lime application, even under a re-acidification scenario. It was possible to verify that Ni immobilization in the soil was increased when biochar was used. Soil Ni immobilization is associated with co-precipitation and chemisorption. Hence, it was demonstrated that biochar is more effective than lime in reducing soil acidity and remedying nickel-contaminated agricultural soils

Experimental analysis on the performance of a pico-hydro Turgo turbine

Gallego Osorio, Edwin Mauricio | 2021

The Turgo turbine is a relatively cheap, reliable and sustainable type of impulse turbine used in hydro- electric plants, which is generally suited for medium and high head applications. Nowadays, the devel- opment and use of technologies for harnessing very low-head water resources have become highly widespread due to the low negative impact generated on the environment. Additionally, the implemen- tation of small innovative water-related projects can be an economical option for the generation of renewable energy in developing countries. Therefore, a low-cost Turgo turbine for low-head applications was designed and manufactured for evaluating the effects of several geometric parameters involved in the design and, subsequently, in the turbine efficiency. Among these parameters, the nozzle diameter, the number of nozzles and the jet impact location were studied. For this purpose, the response surface methodology based on a Box-Behnken design of experiments was used to determine the optimal operat- ing conditions of the referred geometric factors aiming at the maximization of the turbine efficiency, as well as to investigate the effect of each parameter on the turbine efficiency. From the experimental design, a second-order regression model was generated, which was validated. The obtained findings indi- cated that the nozzle diameter had a considerable influence on the turbine efficiency in comparison with the other evaluated factors. Moreover, the results showed that the maximal experimental turbine effi- ciency was equal to 93.7% under optimal design conditions; i.e., when the nozzle diameter, number of nozzles and the jet impact location were equal to 16.685 mm, 2 and 60 mm, respectively. Therefore, the designed Turgo turbine reported a high efficiency, which could be used for the distributed power generation

Application of a central composite face-centered design in the optimization of an Archimedean hydrokinetic turbine

Betancut, J. | 2021

Currently, in the literature, there are no general guidelines for the optimal hydraulic design of Archimedean screw turbines (AST) used in hydrokinetic applications. Therefore, this study is aiming at selecting the most significant geometric factors, such as the diameter ratio between the inner (𝐷�𝑖�) and the outer (𝐷�𝑜�) diameters (i.e., 𝐷�𝑖�/𝐷�𝑜�), the axle length (𝐿�) and the blade stride (𝑝�), influencing the AST performance by using a central composite face-centered (CCF) experimental design combined with the response surface methodology (RSM). The statistical analysis of variance (ANOVA) test identified with a significance level of 0.05 that the most significant variables on the performance of the turbine were 𝑝� and 𝐷�𝑖�/𝐷�𝑜�. The AST efficiency was evaluated by means of the power coefficient (𝐶�𝑃�), which was calculated by means of computational fluid dynamics (CFD) methods coupled with the 6-degrees of freedom (6-DoF) approach. The second-order polynomial model was used to predict the 𝐶�𝑃� and the coefficient of determination (𝑅�2) was found to be 97.4%. Key words. 6-DoF, response surface methodology, Archimedean screw hydrokinetic turbine, central composite design, numerical optimization.