Urtubia Urbina, Alejandra Pamela

The analysis of Cu distribution in pre-treated mine tailings after electrodialytic remediation was carried out by using two methods of sequential extraction. The initial content of copper in the tailings was 1109 mg Cu/kg of dry tailing, where close to 40% of the sample in weight corresponded to a soluble fraction. The tailing was treated with a leaching solution for 24 h. Three different solutions were tested: H2SO4 + HNO3 with pH = 1.9; H2SO4 + HNO3 with pH = 4.2; and NH4Cl 0.8 mol/L with pH = 5.5. After that, electrodialytic remediation experiments were carried out using an electric field of 2.7 V/cm for 15 days. The best performance for the complete cell was obtained with H2SO4 + HNO3 solutions, with a copper removal efficiency in the range of 62% to 67% and a current efficiency between 6% and 9%. The results of the remaining copper concentration between anode and cathode, from both procedures of sequential extraction, showed similar trends. The differences were mainly attributed to the use of different extractant solutions and extraction times. Soluble and exchangeable fractions were easily removed, with efficiencies higher than 80%. The lowest copper removal efficiency was obtained with NH4Cl 0.8 mol/L.

Organic nitrogen plays a significant role in the fermentation performance and production of esters and higher alcohols. This study assessed the use of yeast protein hydrolysate (YPH) as a nitrogen source for grape must fermentation. In this study, we prepared an enzymatic protein hydrolysate using yeasts recovered from a previous fermentation of wine. Three treatments were performed. DAP supplementation was used as a control, while two YPH treatments were used. Low (LDH) and high degrees of hydrolysis (HDH), 3.5% and 10%, respectively, were chosen. Gas chromatography and principal component analysis indicated a significant positive influence of YPH-supplementations on the production of esters and higher alcohols. Significantly high concentrations of 3-methyl-1-penthanol, isoamyl alcohol, isobutanol, and 2-phenylethanol were observed. Significant odorant activity was obtained for 3-methyl-1-pentanol and ethyl-2-hexenoate. The use of YPH as nitrogen supplementation is justified as a recycling yeasts technique by the increase in volatile compounds.