Suchergebnisse

Abstract
Background
Fly ashes from municipal solid waste incineration contain significant amounts of (technology critical) elements. Processes to recover Cu or Zn are already in practice, but it still remains difficult to evaluate the full secondary resource potential of the ashes. One reason is the absence of a worldwide comparable analytical basis for detailed market analyses. To encounter this, (i) an advice on how to analyse 65 elements after microwave-assisted digestion by ICP-OES and ICP-MS is delivered, (ii) the heterogeneity (hours to annual cycle) is evaluated for a incineration plant, (iii) leaching efficiency with three different eluents and (iv) the market potential of the elements as commodities are evaluated.

Results and conclusions
Aqua regia digestion was found to be sufficient to evaluated the recovery potential; except for the mass constituents Al, Si, Sn, Ti and the trace components Cr, Hf, Nb, U and W, for which HF-containing digestions delivered better recoveries. On different time scales, ashes were very homogenous and HCl- as well as H2SO4-supported leaching delivered, satisfying results within an hour (exceptions are, e.g., Bi and Sb). By applying characterisation factors of the life cycle assessment impact category "Resource depletion—minerals and metals" supplemented by the list of critical raw materials of the EU: Ag, Bi, Cd, Ga, In and Sb are most interesting elements to be recovered in future activities.

91 Páginas, 4 Tablas, 6 Figuras ; Optimal supply of trace elements (TE) is a prerequisite for microbial growth and activity in anaerobic digestion (AD) bioprocesses. However, the required concentrations and ratios of essential TE for AD biotechnologies strongly depend on prevailing operating conditions as well as feedstock composition. Furthermore, TE in AD bioreactors undergo complex physico-chemical reactions and may be present as free ions, complex bound or as precipitates depending on pH, or on the presence of sulfur compounds or organic macromolecules. To overcome TE deficiency various commercial mineral products are typically applied to AD processes. The addition of heavy metals poses the risk of overdosing operating systems, which may be toxic to microbial consortia and ultimately the environment. Adequate supplementation, therefore, requires not only appropriate knowledge about the composition, but also on the speciation and bioavailability of TE. However, very little is yet fully understood on this specific issue. Evaluations of TE typically only include the measurement of total TE concentrations but do not consider the chemical forms in which TE exist. Thus detailed information on bioavailability and potential toxicity cannot be provided. This review provides an overview of the state-of-the-art in approaches to determine bioavailable TE in anaerobic bioprocesses, including sequential fractionation and speciation techniques. Critical aspects and considerations, including with respect to sampling and analytical procedures, as well as mathematical modelling, are examined. The approaches discussed in this review are based on our experiences and on previously published studies in the context of the 'COST Action 1302: European Network on Ecological Roles of Trace Metals in Anaerobic Biotechnologies'. ; This article is based upon work from COST Action 1302 ('European Network on Ecological Roles of Trace Metals in Anaerobic Biotechnologies') supported by COST (European Cooperation in Science and Technology). EvH and GE acknowledge support from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 643071 ('Advanced Biological Waste-to-Energy Technologies – ABWET'). GC acknowledges funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme grant agreement No. 261330. The authors thank the two anonymous reviewers for their comments, which significantly improved the quality of the manuscript. ; Peer reviewed

AbstractWith the nationwide introduction of wastewater treatment the overall water quality improved significantly, but challenges remain, including diffuse pollution, historical sediment contamination and the presence of a multitude of anthropogenic chemical species. The implementation of several EU directives in the twenty-first century led to a stronger focus on improving water and sediment quality and the sustainable management of sediments at river basin scale. Hence, in the last 25 years, not only have the regulatory frameworks significantly changed, but also the scientific backbone of our products, delivered to Germany's federal ministries, practitioners from the German Waterways and Shipping Administration, German federal states and the public. In this respect, approaches such as non-target screening, multi-element analysis, effect-based methods, novel approaches in microplastic and nanoparticle analysis and the benefits from the increase in digitalization and automation are key methods and processes to face future challenges, especially those connected to the global climate crisis.