Thiourea leaching of gold from processed municipal solid waste incineration residues

Incineration is one of the key technologies in disposal of municipal waste, which produces municipal solid waste incineration (MSWI) residues with high valuable metal contents. The recycling strategy for the MSWI residues is typically focused on the recovery of scrap metals yielding processed municipal solid waste incineration residues (PIR) as the main byproduct. However, the PIR still contains valuable metals, particularly gold, which cannot be extracted by conventional methods. Here, we evaluated the feasibility of using the 0.5–2.0 mm grain size fraction of PIR containing 28.82 ± 1.62 mg/kg of gold as raw material for a two-stage extraction process. In the first stage the alkalic fine-grained PIR was acidified with a solution of 20% (v/v) of HCl-containing flue gas cleaning liquid that is obtained by the municipal waste incineration plant itself as a waste product. In the second stage we leached the acidified fine-grained PIR by thiourea with Fe³⁺ as an oxidant. Application of the thiourea-Fe³⁺ leaching system resulted in recovery of 16.4 ± 1.56 mg/kg of gold from the fine-grained PIR within 6 h of incubation. Due to high gold market prices, upscaling of the suggested technology can represent a suitable strategy for gold recovery from PIR and other MSWI residues.

     

Does the antidiabetic drug metformin affect embryo development and the health of brown trout (<Emphasis Type="Italic">Salmo trutta</Emphasis> f. <Emphasis Type="Italic">fario</Emphasis>)?

Background

Due to the rising number of type 2 diabetes patients, the antidiabetic drug, metformin is currently among those pharmaceuticals with the highest consumption rates worldwide. Via sewage-treatment plants, metformin enters surface waters where it is frequently detected in low concentrations (µg/L). Since possible adverse effects of this substance in aquatic organisms have been insufficiently explored to date, the aim of this study was to investigate the impact of metformin on health and development in brown trout (Salmo trutta f. fario) and its microbiome.

Results

Brown trout embryos were exposed to 0, 1, 10, 100 and 1000 µg/L metformin over a period from 48 days post fertilisation (dpf) until 8 weeks post-yolk sac consumption at 7 °C (156 dpf) and 11 °C (143 dpf). Chemical analyses in tissues of exposed fish showed the concentration-dependent presence of metformin in the larvae. Mortality, embryonic development, body length, liver tissue integrity, stress protein levels and swimming behaviour were not influenced. However, compared to the controls, the amount of hepatic glycogen was higher in larvae exposed to metformin, especially in fish exposed to the lowest metformin concentration of 1 µg/L, which is environmentally relevant. At higher metformin concentrations, the glycogen content in the liver showed a high variability, especially for larvae exposed to 1000 µg/L metformin. Furthermore, the body weight of fish exposed to 10 and 100 µg/L metformin at 7 °C and to 1 µg/L metformin at 11 °C was decreased compared with the respective controls. The results of the microbiome analyses indicated a shift in the bacteria distribution in fish exposed to 1 and 10 µg/L metformin at 7 °C and to 100 µg/L metformin at 11 °C, leading to an increase of Proteobacteria and a reduction of Firmicutes and Actinobacteria.

Conclusions

Overall, weight reduction and the increased glycogen content belong to the described pharmaceutical effects of the drug in humans, but this study showed that they also occur in brown trout larvae. The impact of a shift in the intestinal microbiome caused by metformin on the immune system and vitality of the host organism should be the subject of further research before assessing the environmental relevance of the pharmaceutical.

     

Prenatal testing for imprinting disorders: A laboratory perspective

Imprinting Disorders (ImpDis) are a group of congenital syndromes associated with up to four different types of molecular disturbances affecting the monoallelic and parent-of-origin specific expression of genomically imprinted genes. Though each ImpDis is characterized by aberrations at a distinct genetic site and a specific set of postnatal clinical signs, there is a broad overlap between several of them. In particular, the prenatal features of ImpDis are non-specific. Therefore, the decision on the appropriate molecular testing strategy is difficult. A further molecular characteristic of ImpDis is (epi)genetic mosaicism, which makes prenatal testing for ImpDis challenging. Accordingly, sampling and diagnostic workup has to consider the methodological limitations. Furthermore, the prediction of the clinical outcome of a pregnancy can be difficult. False-negative results can occur, and therefore fetal imaging should be the diagnostic tool on which decisions on the management of the pregnancy should be based. In summary, the decision for molecular prenatal testing for ImpDis should be based on close exchanges between clinicians, geneticists, and the families before the initiation of the test. These discussions should weigh the chances and challenges of the prenatal test, with focus on the need of the family.     

Land cover transitions and effects of transhumance on available forage biomass of rangelands in Benin

This study examined the effects of transhumance pressure on total abavoe-ground biomass and forage availability on rangelands in Benin. We also investigated the implications of land cover transitions on rangelands over a 31-year period. Our work was carried out in three regions of Benin representing distinct phytogeographic regimes: Ketou, Tchaourou, and Sinende. Ground-truthing and biomass sampling of the herbaceous and phanaerophyte strata were carried out between the 2016 peak vegetation period and the onset of the 2017 rainy season. Herbaceous biomass was determined by destructive sampling, and biomass of shrub and trees was estimated using non-destructive sampling and allometric equations. Historical and present-day Landsat data allowed an analysis of land cover change for the 1986–2002 and 2002–2017 periods. Land cover analyses yielded evidence of significant expansion of agricultural areas, especially in the latter period. The data also revealed progressive landscape fragmentation and transformations to a land cover of reduced total phytomass. There were no long-term effects of transhumance on trees, but likely on herbaceous biomass. Land cover changes in the study regions seem primarily the result of population pressure, infrastructural changes, persisting norms, and traditions regarding environmental management and the increasing popularity of livestock keeping as an insurance strategy. Rangeland transformations had negative impacts on transhumant herds’ mobility and forage availability. As rangeland stability and consent between agricultural and pastoral land users are at a tipping point, informed policies, and land use planning that foster compromises among all stakeholders are needed.

     

Groundwater Flow Model Calibration of a Coastal Multilayer Aquifer System Based on Statistical Sensitivity Analysis

Environmental Modeling & Assessment - The identification of the hydrological processes taking place at coastal systems and the interaction between aquifers and the sea have been key features...