The aim of the present work was the simultaneous treatment of urban wastewater using microalgae and the energetic valorization of the obtained biomass. Chlorella vulgaris (Cv) Scenedesmus obliquus (Sc) and a naturally occurring algal Consortium C (ConsC) were grown in an urban wastewater. The nutrient removals were quite high and the treated water fits the legislation (PT Dec-Lei 236/98) in what concerns the parameters analysed (N, P, COD). After nutrient depletion the microalgae remained two more weeks in the photobioreactor (PBR) under nutritional stress conditions, to induce sugar accumulation (22-43%). The stressed biomass was converted into biohydrogen (bioH 2), a clean energy carrier, through dark fermentation by a strain of the bacteria Enterobacter aerogenes. The fermentation kinetics were monitored and fitted to a modified Gompertz model. The highest bioH 2 production yield was obtained for Scenedesmus obliquus (56.8 mL H 2 /g SV) which was very similar when using the same algae grown in synthetic media.
To make the coffee activity competitive, some farmers use precision coffee farming. Thus, it is possible to create thematic maps that guide management practices for regions where there are limitation for the plant development. The objective of this study was to identify the spatial dependence of coffee crop yield, in 2012 and 2013. The experimental area is located in a Haplustox in Três Pontas, Minas Gerais. One hundred sampling points were georeferenced for the collection of yield data through manual harvest. The difference of yield between crop seasons was also evaluated. Data were processed using geostatistical analysis. It was possible to identify and characterize the spatial dependence of all variables, as well as to create contour maps. There were differences between the 2012 and 2013 maps, due to the biennial coffee phenological cycle, which can be confirmed by the map of the difference between the crop seasons. It is recommended a crop management that considers the spatial variability of yield for greater economic return.
Chia ( Salvia hispanica ) is an annual oilseed crop of high nutritional value. This study aimed to analyze the performance of chia plants sown at different times and grown under different phosphorus rates. The experiment was conducted under field conditions at the Experimental Farm of the State University of Maringá, Umuarama, Brazil. Treatments were arranged in a randomized split-plot design with three replications. Phosphorus fertilizer was applied at the time of sowing at rates of 0, 40, 80, or 120 kg P 2 O 5 ha −1 . Seeds were sown on four dates at 14-day intervals, starting on March 21, 2017, for the first crop and March 29, 2018, for the second crop. Plant population density, raceme number, shoot dry matter yield, thousand seed weight, seed yield, and seed oil content were determined. It was observed that the end of March is the borderline for chia cultivation, because the low temperature and rainfall conditions occurring after this period compromise chia growth. The best phosphorous rate for chia growth was 80–120 kg ha −1 , which led to optimum vegetative parameters.
Chia (Salvia hispanicaL.) is an annual herbaceous plant considered as natural omega-3 fatty acids source. To quantify this oil in seeds, a time-consuming method involving financial costs with chemical reagents is used. The objective of this work was verifying existence of correlation between the quantification of oil in chia seeds by means of the Soxhlet method with the ash mass of these seeds obtained by calcination in a muffle oven. For this, samples of chia seeds and the oil quantified by Soxhlet were collected. The same samples were calcined in ash. The simple correlation test was performed, obtaining linear regression. To method validation, a completely randomized design experiment was carried out. The treatments were to quantify the oil by the Soxhlet method and calcination in the muffle using the equation obtained. The objective was to verify the existence of correlation between the oil content of chia seeds, obtained by the Soxhlet method with ash content obtained after burning in the muffle and, therefore, the validation of this method of determination. There is a significant positive correlation between the oil content obtained by Soxhlet method and the ash mass of chia seed. By equation Y = -2.5319x + 16.518, it was noted that it is feasible to quantify the oil content
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