title: Aplication of the statistical experimental design to optimize mine-impacted water (MIW) remediation using shrimp-shell.
abstract: Mine-impacted water (MIW) is one of the most serious mining problems and has a high negative impact on water resources and aquatic life. The main characteristics of MIW are a low pH (between 2 and 4) and high concentrations of SO42-and metal ions (Cd, Cu, Ni, Pb, Zn, Fe, Al, Cr, Mn, Mg, etc.), many of which are toxic to ecosystems and human life. Shrimp shell was selected as a MIW treatment agent because it is a low-cost metal-sorbent biopolymer with a high chitin content and contains calcium carbonate, an acid-neutralizing agent. To determine the best metal-removal conditions, a statistical study using statistical planning was carried out. Thus, the objective of this work was to identify the degree of influence and dependence of the shrimp-shell content for the removal of Fe, Al, Mn, Co, and Ni from MIW. In this study, a central composite rotational experimental design (CCRD) with a quadruplicate at the midpoint (22) was used to evaluate the joint influence of two formulation variables-agitation and the shrimp-shell content. The statistical results showed the significant influence (p < 0.05) of the agitation variable for Fe and Ni removal (linear and quadratic form, respectively) and of the shrimp-shell content variable for Mn (linear form), Al and Co (linear and quadratic form) removal. Analysis of variance (ANOVA) for Al, Co, and Ni removal showed that the model is valid at the 95% confidence interval and that no adjustment needed within the ranges evaluated of agitation (0-251.5 rpm) and shrimp-shell content (1.2-12.8 g L-1). The model required adjustments to the 90% and 75% confidence interval for Fe and Mn removal, respectively. In terms of efficiency in removing pollutants, it was possible to determine the best experimental values of the variables considered as 188 rpm and 9.36 g L-1of shrimp-shells.
authors.affiliation: Department of Environmental Engineering, Federal University of Santa Catarina (UFSC), Campus Reitor João David Ferreira Lima, 88040-900, Florianópolis, SC, Brazil. Electronic address: damaris_ng@hotmail.com.
authors.forename: Dámaris
authors.initials: D
authors.lastname: Núñez-Gómez
authors.affiliation: Department of Environmental Engineering, Federal University of Santa Catarina (UFSC), Campus Reitor João David Ferreira Lima, 88040-900, Florianópolis, SC, Brazil; Federal University of Fronteira Sul (UFFS), Rua Jocob Reinaldo Haupenthal, 1580, 97900-000, Cerro Largo, RS, Brazil.
authors.forename: Alcione Aparecida de Almeida
authors.initials: AAA
authors.lastname: Alves
authors.affiliation: Department of Environmental Engineering, Federal University of Santa Catarina (UFSC), Campus Reitor João David Ferreira Lima, 88040-900, Florianópolis, SC, Brazil.
authors.forename: Flavio Rubens
authors.initials: FR
authors.lastname: Lapolli
authors.affiliation: Department of Environmental Engineering, Federal University of Santa Catarina (UFSC), Campus Reitor João David Ferreira Lima, 88040-900, Florianópolis, SC, Brazil; Federal University of Santa Catarina (UFSC), Rua Pedro João Pereira, 150, Mato Alto, 88900-000, Araranguá, SC, Brazil.
authors.forename: María A
authors.initials: MA
authors.lastname: Lobo-Recio
mesh_terms: D000704:Analysis of Variance; D060105:Animal Shells / Q000737:chemistry*; D000818:Animals; D002686:Chitin / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019216:Metals, Heavy / Q000032:analysis*; D008906:Mining; D012107:Research Design; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods / Q000706:statistics & numerical data
chemical_list: D019216:Metals, Heavy; D014874:Water Pollutants, Chemical; D002686:Chitin
keywords: Acid mine drainage; Chitin; Metal ions; Remediation; Sorption; Statistics