Companies’ E-waste Estimation Based on General Equilibrium The­ory Context and Random Forest Regression Algorithm in Cameroon: Case Study of SMEs Implementing ISO 14001:2015

Given the challenge of estimating or calculating quantities of waste electrical and electronic equipment(WEEE)in developing countries,this article focuses on predicting the WEEE generated by Cameroonian small and medium enterprises(SMEs)that are engaged in ISO 14001:2015 initiatives and consume electrical and electronic equipment(EEE)to enhance their performance and profitability.The methodology employed an exploratory approach involving the application of general equilibrium theory(GET)to contextualize the study and generate relevant parameters for deploying the random forest regression learning algorithm for predictions.Machine learning was applied to 80%of the samples for training,while simulation was conducted on the remaining 20%of samples based on quantities of EEE utilized over a specific period,utilization rates,repair rates,and average lifespans.The results demonstrate that the model’s predicted values are significantly close to the actual quantities of generated WEEE,and the model’s performance was evaluated using the mean squared error(MSE)and yielding satisfactory results.Based on this model,both companies and stakeholders can set realistic objectives for managing companies’WEEE,fostering sustainable socio-environmental practices.

Managing economic and social profit of cooperative models in three-echelon reverse supply chain for waste electrical and electronic equipment

In addition to maximizing economic benefits, reverse supply chains should further seek to maximize social benefits by increasing the quantity of waste electrical and electronic equipment （WEEE）. The paper investigates cooperative models with different parties in a three-echelon reverse supply chain for WEEE consisting of a single collector, a single remanufacturer, and two retailers based on complete information. In acldition, the optimal decisions of four cooperative models and the effect of the market demand of remanufactured WEEE products and the market share of two retailers on the optimal decisions are discussed. The results indicate that optimal total channel profit and recycle quantity in a reverse supply chain are maximized in a centralized model. The optimal total channel profit and recycle quantity increase with an increase in the market demand of remanufactured WEEE products. The three-echelon reverse supply chain consisting of duopolistic retailers maximizes total channel profit and recycle quantity in a reverse supply chain fbr WEEE.

Comparative studies on hydrometallurgical treatment of smelted low-grade electronic scraps for selective copper recovery

A comparison of three hydrometallurgical methods for selective recovery of copper from low-grade electric and electronic wastes was reported. Scraps were smelted to produce Cu？Zn？Sn？Ag alloy. Multiphase material was analyzed by SEM？EDS and XRD. The alloy was dissolved anodically with simultaneous metal electrodeposition using ammoniacal and sulfuric acid solutions or leached in ammonia？ammonium sulfate solution and then copper electrowinning was carried out. This resulted in the separation of metals, where lead, silver and tin accumulated mainly in the slimes, while copper was transferred to the electrolyte and then recovered on the cathode. The best conditions of the alloy treatment were obtained in the sulfuric acid, where the final product was metal of high purity （99% Cu） at the current efficiency of 90%. Ammoniacal leaching of the alloy led to the accumulation of copper ions in the electrolyte and further metal electrowinning, but the rate of the spontaneous dissolution was low. Anodic dissolution of the alloy in the ammonia？ammonium sulfate solution led to the unfavorable distribution of metals among the slime, electrolyte and cathodic deposit.

Recovery of Metals from Anodic Dissolution Slime of Waste from Electric and Electronic Equipment（WEEE） by Extraction in Ionic Liquids

The recovery of metals from a multi-component alloy obtained by crushing, melting and anodic dissolution of waste from electric and electronic equipment（WEEE） was investigated. The anodic dissolution of the alloy was carried out in an electrolysis cell with one copper cathode and a central cast anode, immersed in the electrolyte formed by choline chloride-ethylene glycol-iodine. The temperature of the electrolyte during the process was 343 K. Depending on the electrolysis parameters（current density and cell voltage）, cathodic deposits of Sn, Pb and Zn of 〉99% purity were obtained. Cyclic voltammetry was used in order to determine the deposition potentials of the studied metals. The obtained metallic deposits were subject of determination of XRD, SEM/EDX and AFM in order to evidence the deposits structure and morphology. The experiments performed demonstrated the possibility of separating/selective recovery of metals from the multi-component alloy resulted from the waste from electrical and electronic equipment by anodic dissolution in ionic liquids.

Methodology for Precious Metal Recovery in Computer Printed Circuit

The life of electronic equipment is becoming increasingly shorter and its replacement always generates a quantity of waste increase, giving rise to a problem of environmental character and still needed new options of solid waste management that will contribute to global sustainable development. Parts of these waste are TCI （the card＇s printed circuit） which containing dangerous elements and turns them into a polluting material from the soil, water and air, being harmful to human health if there is to proper and responsible way, so the recycling of TCI to obtain precious metals is an example of industrial materials that can be recycled. Despite this, large quantities of these are not recycled and some others are not considered. The objective of this work is to present a systematic and ecological methodology for the recovery of valuable materials contained in parts of used in computers, circuit boards using a leaching process. The method determines a set of variables to evaluate the kinetics of the reaction and the leaching of metals that form the substrate of metal and to establish the parameters that affect the rate of leaching of metals through a sensitivity analysis, to identify design alternatives. It determines the quantity and percentages that constitutes the motherboard, processor, video cards, accelerator graphics, network and memory cards RAM, among others and its content of metals such as Cu, Fe, Ag, Au and Pt.

An updated review and conceptual model for optimizing WEEE management in China from a life cycle perspective

Waste electrical and electronic equipment （WEEE） is a rapidly growing category of solid waste. China is now facing WEEE problems from both growing domestic generation and illegal imports. Currently, the amount of WEEE formally treated has increased steadily in China. The layout of the formal sector has been basically completed. Meanwhile, by controlling illegal disassembly activities, the informal sector has been gradually transformed to formal one. Beginning with the overview of the WEEE recycling industry in China, this paper first lists the latest progress in WEEE management from such aspects as the new edition of China RollS Directive （Restriction of Hazardous Substances Directive）, the updated WEEE Treatment List, the updated WEEE fund standard, the revised National Hazardous Waste List, and a brand-new plan on extended producer responsibility. In so doing, we elucidate the current challenges on WEEE management in detail： the imbalance between fund levies and subsidies, the gap in the supervision scope, the homogenization of recycling industry and the lack of life cycle approaches. Finally, a conceptual framework for integrated management of WEEE is proposed from a life cycle perspective. Overall, the life cycle management of WEEE includes three aspects： developing life cycle information for decision-making, implementing life cycle engineering with life cycle tools, and improving WEEE legislation based on life cycle thinking. By providing specific operating strategies, this life cycle framework should help to optimize WEEE management in developing countries where legislation is imperfect and the recycling system is relatively immature.

Comparison on End-of-Life strategies of WEEE in China based on LCA

As the Electrical and Electronic Equipment （EEE） are upgraded more frequently in China, a large quantity of Waste Electrical and Electronic Equipment （WEEE） was and will be generated. It becomes an urgent issue to develop and adopt an effective End-of-Life （EoL） strategy for EEE in order to balance the resource recovery and environmental impacts. In an EoL strategy hierarchy for EEE, reuse strategy is usually deemed to be prior to materials recovery and other strategies. But in practice, the advantages and disadvantages of different strategies are always context-dependent. Therefore, main EoL strategies for EEE in China need to be evaluated in environment and resources aspects from the life cycle perspective. In this study, the obsolete refrigerator and Power Supply Unit （PSU） ofdesktop PC are both taken as the target products. Life Cycle Assessment （LCA） is applied to assess the environmental impacts of different EoL scenarios in China： Unit Reuse Scenario （URS）, Component Reuse Scenario （CRS） and Materials Recovery Scenario （MRS）. The LCA results show that the EoL strategies hierarchy is reasonable for the part＇of computer, bui not necessarily suitable for obsolete refrigerators. When the policy makers promote or demote one EoL strategy especially reuse, it is necessary to take subsequent impacts into consideration.

Pyrolysis of WEEE plastics using catalysts produced from fly ash of coal gasification

Catalytic pyrolysis of thermoplastics extracted from waste electrical and electronic equipment （WEEE） was investigated using various fly ash-derived catalysts. The catalysts were prepared from fly ash by a simple method that basically includes a mechanical treatment followed by an acid or a basic activation. The synthesized catalysts were characterized using various analytical techniques. The results showed that not treated fly ash （FA） is characterized by good crystallinity, which in turn is lowered by mechanical and chemical treatment （fly ash after mechanical and acid activation, FAMA） and suppressed almost entirely down to let fly ash become completely amorphous （fly ash al^er mechanical and basic activation FAMB）. Simultaneously, the surface area resulted increased. Subsequently, FA, FAMB and FAMA were used in the pyrolysis of a WEEE plastic sample at 400~C and their performance were compared with thermal pyrolysis at the same temperature. The catalysts principally improve the light oil yield： from 59 wt.% with thermal pyrolysis to 83 wt.% using FAMB. The formation of styrene in the oil is also increased： from 243 mg/g with thermal pyrolysis to 453 mg/g using FAMB. As a result, FAMB proved to be the best catalyst, thus producing also the lowest and the highest amount of char and gas, respectively.

Improvement potential of today＇s WEEE recycling performance： The case of LCD TVs in Belgium

Waste of electrical and electronic equipment （WEEE） constitutes one of the most relevant waste streams because of the quantity and presence of valuable materials. However, there is limited knowledge on the resource potential of urban mining WEEE, as data on material composition, and the efficiency of current recycling treatments are still scarce. In this article, an evaluationof the recycling performance at a national level for one of the fastest growing e-waste streams： LCD TVs is carried out through the following four steps. Firstly, material characterisation is performed by means of sampling of the waste stream. Secondly, a material flow analysis is conducted by evaluating the separation performance of a recycling plant in Belgium..Thirdly, the recovered economic value and avoided environmental impact （EI） of the analysed recycling system is assessed. Finally, the potential of urban mining for Belgium is forecasted. The analysis shows that while recycling performance for ferrous metals and aluminium are relatively high; there is substantial room to better close the material loops for precious metals （PM） and plastics. PMs and plastics account for 66 % of the economic value in LCD TVs and 57% of the El. With the current, commonly applied recycling technology only one-third of the PM and housing plastics are recycled; meaning that for＇these material＇s, at a national level for Belgium, there is a potential for improvement that represents 3.3 million euros in 2016 and 6.8 million euros in 2025.