Process development options for electronic waste fractionation to achieve maximum material value recovery

Revised legislation and bans on imports of waste electrical and electronic equipment (WEEE) into many Asian countries for treatment are driving the need for more efficient WEEE fractionation in Europe by expanding the capacity of treatment plants and improving the percentage recovery of materials of economic value. Data from a key stakeholder survey and consultation are combined with the results of a detailed literature survey to provide weighted matrix input into multi-criteria decision analysis calculations to carry out the following tasks: (a) assess the relative importance of 12 process options against the 6 industry-derived in-process economic potential criteria, that is, increase in product quality, increase in recycling rate, increase in process capacity, decrease in labour costs, decrease in energy costs and decrease in disposal costs; and (b) rank 25 key technologies that have been selected as being the most likely to benefit the efficient sorting of WEEE. The results indicate that the first stage in the development of any total system to achieve maximum economic recovery of materials from WEEE has to be the selection and application of appropriate fractionation process technologies to concentrate valuable components such as critical metals into the smallest possible fractions to achieve their recovery while minimising the disposal costs of low-value products. The stakeholder-based study has determined the priority for viable technical process developments for efficient WEEE fractionation and highlighted the economic and technical improvements that have to be made in the treatment of WEEE.

Bioleaching of valuable and hazardous metals from dry discharged incineration slag. An approach for metal recycling and pollutant elimination

Recycling of process wastes will be in future an essential step to meet the demands for valuable metals of a growing market. Depending on their particle sizes incineration slags are already used to recover metals but particle size fractions below 4 mm are still difficult to recycle. Therefore, different particle size fractions (mesh size 2 and 4 mm, high energy grinded) of dry discharged slags were used for bioleaching with and without the pure cultures Acidithiobacillus ferrooxidans or Leptospirillum ferrooxidans or a mixture of Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans in batch cultures. Regarding Al, Cr, Cu, Ni, Mn and the rare earth elements Ce, La and Er, bioleaching was significantly more successful with iron oxidizing bacteria compared to abiotic controls. Metal mobilization for Al, Cu, Mn, Cr and Er with bacteria was between 70 and 100% and for Ce, Ni and La around 50% almost after 7 days, making an industrial application for the high concentrated metals like Al and Cu feasible. In addition to the recovery of valuable metals, a reduction in cost of landfilling was identified. After treatment of the slag with the microorganisms, concentrations of harmful substances in the residues could be reduced and thus a classification in lower safety levels regarding the LAGA or EU regulations was calculated.

Effects of OCT1 polymorphisms on the cellular uptake, plasma concentrations and efficacy of the 5-HT(3) antagonists tropisetron and ondansetron

After uptake into liver cells, the antiemetic drugs tropisetron and ondansetron undergo metabolic inactivation by cytochrome P450 2D6 (CYP2D6). We investigated whether the hepatic organic cation transporter 1 (OCT1; SLC22A1) mediates cellular uptake and whether common OCT1 loss-of-function polymorphisms affect pharmacokinetics and efficacy of both drugs. Both tropisetron and ondansetron inhibited ASP(+) uptake in OCT1-overexpressing HEK293 cells. Overexpression of wild-type, but not OCT1 loss-of-function variants, significantly increased tropisetron uptake. Correspondingly, patients with two loss-of-function OCT1 alleles had higher tropisetron plasma concentrations (n=59, P<0.04) and higher clinical efficacy (n=91, P=0.009) compared with carriers of fully active OCT1. Overexpression of OCT1 did not increase ondansetron uptake. Nevertheless, OCT1 genotypes correlated with pharmacokinetics (n=45, P<0.05) and clinical efficacy (n=222, P<0.02) of ondansetron, the effect size of OCT1 genotypes on pharmacokinetics and efficacy was greater for tropisetron than for ondansetron. In conclusion, in addition to the known effects of CYP2D6, OCT1 deficiency may increase efficacy of tropisetron and potentially of ondansetron by limiting their hepatic uptake.