Applied Tests to Select the Most Suitable Fungal Strain for the Recovery of Critical Raw Materials from Electronic Waste Powder

Abstract

Electrical and electronic wastes (WEEEs) are a potential source of raw materials. The main challenge for scientists is to set up a reliable and eco-friendly process to recycle raw materials and precious elements from WEEEs. Today, we know that fungi could play an active role in green technologies aimed at recycling valuable elements. The bioaccumulation mechanism and bioleaching activity of filamentous fungal species have already been exploited fruitfully in extraction processes. However, not all fungal strains possess the same characteristics, and it is crucial to choose the right strains to use. In this work, we show a method to assess the precious elements’ recovery efficiency from WEEE using fungal strains. A CAS agar screening test for siderophore detection was carried out with three strains. The following plate accumulation test performed on a medium added with 120 ppm of electronic waste powder highlighted the differences in accumulation capability, growth rate, and biomass production. Among the elements in tested waste, yttrium, copper, and palladium show the highest bioconcentration factor. The results confirm the biotechnological potential of fungi to recover valuable elements at the bench scale, highlighting the importance of effective screening tests to assess the most efficient strain for each kind of waste.

Impact of Management and Reverse Logistics on Recycling in a War Scenario

“…It is therefore also in the end-of-life phase that the efforts of the WEEE industry should be concentrated, in which the management of reverse logistics assumes relevance, not only for the manifest danger of the substances contained in the equipment, but also for the legal requirements set forth in EU directives. In addition, reverse logistics mainly leverage the economic value that these activities have, particularly with regards to the reintroduction of raw materials in production chains and in reducing environmental impacts, thus producing emerging benefits on the quality of life of populations [59].…”

Fungal Arsenic Tolerance and Bioaccumulation: Local Strains from Polluted Water vs. Allochthonous Strains

“…where W cut is the dry weight of the mycelium of colonies under testing, viz., the colonies of which we want to evaluate the tolerance capabilities; W c is the dry weight of the colonies used as control. The bioconcentration factor (BCF) was estimated as the ratio of the concentration of arsenic present in the dry biomass and the contaminant concentration present in the plates before the fungal inoculation (in our case 1600 µg L −1 ), as suggested by Rosa et al [32][33][34]. The metalloid concentration was evaluated by means of an ICP-MS.…”

“…Indeed, fungi may have different bioconcentration capacities under the same growth conditions. In other works, this parameter was used to select the best performing fungi for bioremediation applications [33]. BCF values larger than 1 give us an indication of the fungal strain's capacity to accumulate metal ions.…”