Assessment of critical factors in waste electrical and electronic equipment (WEEE) plastics on the recyclability: A case study in Finland

Exploring the untapped practices in bacterial-fungal mixed-based cultures for acidic treatment of metal-enriched printed circuit board waste

This study explores the extraction of metals from spent mobile phone printed circuit boards (SMPhPCBs) to address environmental and resource depletion concerns. The challenges in metal recovery from SMPhPCBs arise due to their complex composition and high metal content. While previous research has primarily focused on using bio-cyanide, bio-sulfate, and bio-ferric compounds from acidophilic bacteria, the potential of bio-oxalic acid for SMPhPCBs treatment and the alteration of their complex structure has not yet been explored. Additionally, this study suggests evaluating the untapped potential of Aspergillus niger in oxalic acid production through mixed cultures with bacteria, marking a pioneering approach. A unique culture of Bacillus megaterium and A. niger was created, inducing bio-stress by bacterial metabolites, including gluconic acid (2683 mg/l) and live/dead bacterial cells in a medium with glucose deficiency. Results demonstrated reducing sugar consumption and oxalic acid over-production in mixed cultures compared to pure cultures, ranging from 1350 to 4951 mg/l at an initial glucose concentration (IGC) of 10 g/l and 4276 to 7460 mg/l at IGC 20 g/l. This over-production is attributed to proposed fungal signaling mechanisms to bacteria. Metal extraction using organic acids and siderophores at 10 g/l pulp density, 24 h, and 60 °C yielded Mn (100 %), Pt (100 %), Pd (70.7 %), Fe (50.8 %), Co (48.3 %), Al (21.8 %), among others. The final valuable residue containing copper, gold, and silver holds potential for future recycling. The study concludes with XRD and FTIR analyses to assess the bioleaching effect on the bio-leached powder.

The Effects of Bromine Additives on the Recyclability of Injection Molded Electronic Waste Polymers

Excessive waste amounts, such as waste electrical and electronic equipment (WEEE) and plastic waste, have increased simultaneously with the development of society. Despite the increased material amounts, the recycling rates are too low and those have a great potential to contribute actions toward a circular economy. A certain restricted factor for recycling is the heterogenous nature of materials, such as WEEE-included additives. This study investigates the effects of a WEEE polymer including bromine on recycling ability, analyzing its physical and mechanical features. The study demonstrates that polymer sorting is profitable for WEEE polymers from the material qualitative perspective, because various processability and material features are achieved in the study between material categories, and especially unidentified polymers have the weakest features in the studied tests. The separation of bromine concentration is also recommended because bromine-free materials have more advanced features that can be confirmed by statistical analyses. The achieved results support the idea that novel circular economy actions have the potential for effective, efficient WEEE polymer recycling processes with technological innovations, especially when all variables (e.g., recycling cycles and process parameters) are observed and it enables an option to reduce the need for virgin plastic.

Insight into Bioaccumulation of Decabromodiphenyl Ethane in Eisenia fetida Increased by Microplastics

The rise of electronics inevitably induced the co-pollution of novel brominated flame retardants (NBFRs) and microplastics (MPs). However, studies on how they interact to influence their bioavailability are scarce. Here, we explored the influence mechanism of acrylonitrile butadiene styrene (ABS)-MPs on the bioaccumulation of decabromodiphenyl ethane (DBDPE) in soil-earthworm microcosms. The influence exhibited a temporal pattern characterized by short-term inhibition and long-term promotion. After 28 days of exposure, DBDPE bioaccumulation in a co-exposure (10 mg kg-1 DBDPE accompanied by 1000 mg kg-1 ABS-MPs) was 2.61 times higher than that in a separate exposure. The adsorption process in the soil, intestines, and mucus introduced DBDPE-carried MPs, which had a higher concentration of DBDPE than the surrounding soil and directly affected the bioavailability of DBDPE. MP-pre-exposure (100, 1000, and 10000 mg kg-1) reduced epidermal soundness, mucus secretion, and worm cast production. This eventually promoted the contact between earthworm and soil particles and enhanced the DBDPE of earthworm tissue by 6%-61% in the next DBDPE-postexposure period, confirming that MPs increased DBDPE bioaccumulation indirectly by impairing the earthworm health. This study indicates that MPs promoted DBDPE bioaccumulation via adsorption and self-toxicity, providing new insight into the combined risk of MPs and NBFRs.

Closed-loop supply network of electrical and electronic equipment under carbon tax policy

Waste electrical and electronic equipment is one of the essential pollutants with significant negative impacts on the environment and human health. In this study, a multi-period mixed-integer linear programming model is developed to design a closed loop supply network for the management of electrical and electronic equipment by explicitly considering the economic and environmental sustainability with a budget constraint. Different recycling options like refurbishing, disassembling, remanufacturing, and disposal centers are considered in the design of the network. The model minimizes the total costs of the network and the total carbon emission tax. The literature review shows that the introduced model is more comprehensive than the other existing models because it simultaneously determines the location of facilities, the capacity of facilities, type of manufacturing technologies, variety of vehicles, and the allocation and transportation of materials and products. The model was applied to a real-life case study in Iran and could provide a profit of IRR 245,509,165 M during the planning periods. The carbon tax policy with different echelons is applied to control the environmental impacts in which the carbon tax increases as carbon emissions increase. The results show a nearly linear relationship between the total costs of the network and the carbon tax. The carbon tax of equal to or more than 10,800 IRR/t CO₂ can be a deterrent factor for the electrical and electronic equipment manufacturer in Iran to diminish emissions through investment in green technologies.

Stakeholder Analysis of the Waste Electrical and Electronic Equipment Internet Recycling Industry

With the acceleration of the digitization process and the popularization of the internet, the recycling of waste from electrical and electronic equipment (WEEE) has become a potential and emerging recycling method. Stakeholders in the WEEE internet recycling industry have different roles which need to be clarified. The stakeholder structure and relationships, and stakeholder characteristics, lie at the core of recycling system governance. Therefore, it is necessary to identify stakeholders in the existing WEEE Internet recycling industry. This study selected 10 important stakeholders and classified them into key, potential, and marginal stakeholders using the Mitchell scale while analyzing their characteristics and interactions. The results showed that internet recycling companies, government, residents, and traditional recyclers are key stakeholders that are important for promoting the development of the industry. Based on the above analysis, policy advice is proposed to provide directions for the improvement of the WEEE industry.