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In this study, a new approach to predicting the ability of a hydrometallurgical process to simultaneously remove metal(loid)s, pentachlorophenol (PCP), and polychlorodibenzodioxins and furans (PCDD/F) from contaminated soil is developed. The remediation process consisted of attrition and alkaline leaching steps applied for the coarse (> 0.250 mm) and fine (< 0.250 mm) fractions, respectively. First, a contaminant granulometric distribution-CGD model was established from granulo-chemical analyses performed on 5 selected sampling points collected from the contaminated site to estimate the levels of metallic and organic (PCP, PCDD/F) contamination in the coarse (> 0.250 mm) and fine (< 0.250 mm) fractions of the entire sample (24) and reduce the analytical costs. The accuracy of the CGD model for each contaminant in both fractions was then evaluated by cross-validation. The CGD model, sequential Gaussian simulation (SGS), and linear regression analyses were combined to predict the ability of the attrition and leaching processes applied to the coarse (> 0.250 mm) and fine (< 0.250 mm) soil fractions to simultaneously remove As, PCP, and PCDD/F from contaminated soil, respectively. The results showed that the attrition process could effectively remove the contaminants below the regulation standards to allow the industrial use of the rehabilitated site, as the coarse fraction represents an average proportion of 84 ± 2% of the total soil. However, the leaching process was ineffective in decontaminating the fine fraction (< 0.250 mm), which represented an average proportion of 14 ± 1% of the total soil. Based on these results, the most suitable strategy for this site can be established and a methodological reference for similar studies in risk assessment can be provided. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate, at a pilot scale, the performance of an attrition process for removing As, Cr, Cu, pentachlorophenol (PCP) and polychlorodibenzodioxins and furans (PCDDF) from a 1-4 mm soil fraction. A Box-Behnken experimental design was utilized to evaluate the influence of several parameters (temperature, surfactant concentration and pulp density) and to optimize the main operating parameters of this attrition process. According to the results, the concentration of surfactant (cocamidopropylbetaine-BW) was the main parameter influencing both PCP and PCDDF removal from the 1-4 mm soil fraction by attrition. The behavior of each 2,3,7,8-PCDD/F congener during the attrition process was studied. The results indicated that the concentration of surfactant had a significant and positive effect on the removal of almost all of the dioxin and furan. The removal of 56%, 55%, 50%, 67% and 62% of the contaminants were obtained for As, Cr, Cu, PCP and PCDDF, respectively, using the optimized conditions ([BW]= 2% (w.w−1),T= 25°C and PD = 40% (w.w−1)). These results showed that attrition in the presence of a surfactant can be efficiently used to remediate the coarse fractions of soil contaminated by As, Cr, Cu, PCP and PCDDF. [ABSTRACT FROM PUBLISHER]

BACKGROUND Several techniques have been proposed to recover chitin from shrimp waste using large amounts of freshwater and chemicals. The standard chemical recovery of chitin was first compared by replacing fresh water with seawater. In addition, a biotechnological process with Bacillus subtilis ( B1) and Bacillus licheniformis ( B2) using seawater during all steps of chitin extraction was studied. RESULTS The demineralization rate ( DM) was statistically significant when using seawater ( P=0.000020) and chemical recovery in comparison with deproteinization ( DP). Increasing HCl concentration (from 1 to 1.28 mol L−1) and reaction time (from 60 to 90 min) resulted in DM similar to fresh water ( P>0.05). Highest DP rates were obtained with crude protease ( B1; DP ≈74%) and ( B2: DP ≈84%), when fermentation was carried out for 24 h at an enzyme/substrate ratio of 2. Maximum DP was reached (≈79% for B1 and ≈ 82% for B2) after 15 days, while DM ranged between 55 and 60%. CONCLUSION Combined enzymatic DP (with B2) followed by a chemical DM process was used to produce chitin ( DP≈84%, DM≈94%) which, on transformation to chitosan, showed a degree of deacetylation equivalent to ≈ 71%. This combined approach using seawater could transform crustacean waste into chitin products of commercial value. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]