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.

Impact of Electronic Wastes Recycling on Environmental Quality

Objective To evaluate the environmental quality of Guiyu, Guangdong impacted by the electronic waste recycling industry. Methods The surface water, ground water and sediment samples taken separately from two sites that recycle E-wastes and other rubbish relevant to the E-waste recycling, and an agricultural area, were analyzed, and the data were used to evaluate the impact of E-waste recycling on the environmental quality of Guiyu based on environmental quality standards in China. Results The concentrations of lead and iron in the surface water samples significantly different in the three locations. The maximum value of lead in the first site was 8 times higher than the threshold of environmental quality standards for surface water. The concentration of iron in polluted sample was 22 times that of the background sample. Manganese and iron also showed a significant difference in ground water samples between the three sites. The amount of iron was 22 times that of the threshold of the quality standard for ground water, and 120 times that of the background sample. Moreover, the results of all the eight heavy metals showed significant differences among the sediment samples. The concentrations of copper, cadmium, nickel, and lead in the polluted samples were above the median benchmarks of National Oceanic and Atmospheric Administration （NOAA）. The copper concentration of 2670 mg/kg was 10 times that of the median benchmark. Conclusion E-waste recycling has led to the severe pollution Guiyu.

Selective Adsorption of Ag(I) from Electronic Waste Leachate Using Modified Silk Sericin

A novel biosorbent was synthesized by grafting bisthiourea(BTU)on a silk sericin(SS)matrix.This biosorbent was denoted as BTU-SS and characterized by Fourier transform infrared spectroscopy(FTIR),zeta potential measurements,elemental analysis,and X-ray photoelectron spectroscopy(XPS).As revealed by the adsorption experiments,both BTU-SS and SS showed low affinity towards coexisting base metallic ions in Ag(I)-Cu(II)-Zn(II)-Ni(II)-Pb(II)electronic waste leachate mixtures,while their adsorption capacities towards Ag(I)reached 30.5 and 10.4 mg∙g-1 at a pH of 5.0,respectively.BTU-SS showed higher selectivity towards Ag(I)than SS,as revealed by the Ag(I)partition coefficients between the biosorbents and the leachate(16634.6 and 403.3,respectively).As further demonstrated by column experiments,BTU-SS allowed the separation of Ag(I)from an electronic waste leachate.Thermodynamic studies showed that the adsorption of Ag(I)was exothermic and spontaneous,while adsorption kinetic experiments revealed that chemisorption dominated the adsorption process with activation energies of 47.67 and 53.27 kJ∙mol-1 for BTU-SS and SS,respectively.FTIR and XPS analyses of fresh and Ag(I)-loaded BTU-SS further revealed an adsorption mechanism mainly involving electrostatic and coordination interactions.

Review of Soil Environmental Contamination Caused by Heavy Metals from Electronic Wastes

The reports about soil environmental contamination from heavy metals in electronic wastes were reviewed. The production, sources and disposition of electronic wastes were introduced. The negative impacts of electronic wastes on the environment were analyzed, and soil pollution from electronic wastes in several typical districts were discussed and summarized.

Contamination and Remediation of Heavy Metals in Soils near E-waste Recycling Area

In order to assess heavy metals pollution in agricultural soil after renovation in typical e-waste recycling areas, 212 soil samples were col- lected and the mass fractions of 7 kinds of heavy metals （Cd, Cr, Cu, Hg, Ni, Pb and Zn） were analyzed. The results indicated that heavy metals pollution in agricultural soil was commonly existed in the study areas, and the soil was slightly contaminated by Pb but was moderately or critically polluted by Cd and Cu. However, the carcinogenic risk and non-carcinogenic risk status by heavy metals pollution were beyond acceptable levels, and soil remediation was quite necessary. After some investigations of bioremediation, we found that saponin as washing agent could highly strenqthen the behavior of heavy metals desorption from soil ,which had a good prospect of engineering practice.

Interference-Free Determination of REEs in Electronic Waste Using ICP Optical Emission Spectroscopy

Recently, the demand for REEs （rare earth elements） has been heavily increasing, as they are used in many high-tech products （e.g., because of their specific magnetic behavior）. As a result, the supply situation for REEs is worsening and the world market is depending on Chinese exports, so that it may be worthwhile to recycle e-waste （electronic waste） in European countries. This article describes an analytical method to analyze REEs in different kinds of e-waste with the help of a simultaneous ICP-OES （ICP optical emission spectrometer）. The task is challenging because samples show significant differences in terms of major, minor and trace element concentrations. Depending on the field of application, the level of matrix elements and target elements differs completely, resulting in a wide variety of spectral interferences. The method presented in this article allows an accurate quantification of REEs as well as a high sample throughput. In addition to REEs, other elements of economic interest can be determined in the same way. The development of a sample preparation process is another important issue and considered as well.

Efficiency of Crude α-Cyclodextrin in Gold Recovery from Electronic Waste and Soil

In this study, the metal coordination ability of alpha-cyclodextrin (α-CD) was employed to complex gold and thus isolate and extract it from different matrices of acid-digests of electronic waste and soil. The crude α-CD used was extracted from cassava and yam starch of the non-edible plant species using E. coli α-cyclodextrin glucanotransferase (α-CGTase), with yields ≥ 62%. The reaction was monitored progressively by ultraviolet-visible spectroscopy and checked with infrared spectroscopy (IR) for the presence of α-CD. The crude α-CD extract without need for purification was refluxed with gold containing-electronic waste and soil predigested in a mixture of NaBr/HNO3 for 4 - 7 days. Recoveries of up to 22.9% and 70.8% gold were achieved from electronic waste and soil, respectively using 0.1 M α-CD. This approach is cheap, effective, and environmentally benign.

A study of factors influencing consumers' behavior in recycling waste household electronic appliances

The innovation of technologzv and the improvement of people＇s living standard accelerate the replacement of consumer electronic appliances, resulting in a significant increase of waste household electronic appliances （WHEA）. To address the environmental problems of WHEA, many countries have enacted legislation according to WHEA management, including collecting, processing and recycling. The regulations on the management of WHEA were also drafted in China and pilot programs of WHEA recycling management encountered difficulties in collecting WHEA. The success of a recycling scheme is dependent on people＇s willingness of participating in the scheme, This paper applies Ajzen＇s theory of planned behavior to seek the main factors to engourage consumers to participate in WHEA recycling management in China. Data from a survey conducted with a sample of 633 consumers show that service motivation is the first predictor of participation behavior intention, followed by environmental behavior attitude, economic motivation, subjective norm. and perceived behavior barrier. Environmental knowledge is found not to be the predictor of behavior intention in this recycling scheme. Study results also suggest that publicity is the key situational factor in the WHEA recycling management. Recycling network and policy have little influence on changing consumers＇ current behavior intention and participation. Implications of the findings are discussed and future research directions are suggested in the end.

Effect of Partial Replacement of Coarse Aggregate with Electronic Waste Plastic in Light Weight Concrete

This study assessed the usefulness of the replacement of coarse aggregate partially with electronic waste(e-waste)plastic in lightweight concrete since developing countries have been challenged with management of e-waste as well as high cost of coarse aggregates for concrete production.Coarse aggregates were replaced with e-waste plastic in concrete at 5%,10%,15%,and 20% for a concrete class of C20.The particle size distribution of the e-waste plastic aggregates was determined as well as the slump,compressive strength,water absorption and bulk density of the concrete.Generally,the slump decreased as the e-waste increased.The compressive strengths decreased for the 5%and 10%replacement of coarse aggregates with e-waste but increased for the 15% and 20% replacement of coarse aggregate with e-waste.0% water absorption was obtained for the 15% and 20% e-waste content while the 10%e-waste concrete obtained 0.01% and the 5% e-waste obtaining of 0.013% after 28days of curing.The densities of 5%,10%,15% and 20% e-waste plastic content decreased as compared to the 0% e-waste plastic content.The values of compressive strength obtained showed that coarse aggregate replacements by e-waste plastic at 15% and 20% may be appropriate for lightweight concrete of class C20/25 since compressive strengths ranged between 16.09 Nmm^(-2) and 22.87 Nmm^(-2).This implies that partial replacement of coarse aggregate with e-waste plastic may be useful for lightweight concrete as well as helping in eradicating the environment of the menace of e-waste plastic.

Electrical and Electronic Waste in Northwest Mexico

The waste derived from Electrical and Electronic Equipment (WEEE) is of interest now worldwide, in some countries due to the rapid technological development and in others due to technological dependence through the acquisition of second hand equipment. Therefore it is necessary to implement strategies for the sustainable management of electrical and electronic equipment at the end of its useful life. This paper presents the results of an investigation that was conducted in a city located in the Northwest of Mexico, which seeks to understand the management practices of household WEEE generators. A survey was applied to a representative sample of the population with a confidence level of 90%. Six home appliances were quantified and it was found that approximately 21% of them are disposed directly as part of the household flow of Municipal Solid Waste (MSW), while 79% are storage for a latter sale, repair or reuse. The results obtained support the need to develop evaluations and to implement possible scenarios for the sustainable management of Electrical and Electronic Waste.

Recycling of Electronic Waste, Using Basic and Acid Leaching

This recycling of printed circuit board (TCI) for the production of metals, given the environmental degradation that can cause toxic substances of these, is the reuse of valuable materials recovered from the TCI, this being an economic engine that promotes the recycling of this waste. This paper presents a methodology for evaluating the reaction kinetics and leaching of metals that form the metal substrate, which have environmental and energy advantages, so the generation of new recovery techniques metals from the TCI low environmental and energy impact is increasingly necessary, for it is essential to establish the parameters affecting the reaction rate and identify design alternatives to determine whether or not sustainable, economically viable and that does not pollute. The method adopted was a leaching acid samples, where the full factorial method employed two experimental levels to evaluate the influence of: leaching time, temperature of the aqueous leach solution, reaction kinetics and solid/liquid, on the percentage of metal extraction. Subsequently, the metals are obtained by calcining and smelting the resulting salts by addition of acid liquor.

THE EFFECTIVENESS OF ELECTRICAL AND ELECTRONIC WASTE RECYCLING AND ITS IMPLICATIONS TO GREEN BUILDING:Empirical Studies in India and Switzerland

The life of consumer electrical and electronic(E&E)devices is relatively short,and decreasing as a result of rapid changes in equipment features and capabilities.This creates a large waste stream of obsolete E&E equipment.Even though there are conventional disposal methods for E&E waste,these methods have disadvantages from both economic and environmental viewpoints.This paper examines the existing recycling situations and collection methods of E&E waste in India and Switzerland.Questionnaire survey,interview discussions and case studies are conducted.Their E&E waste scenario and technologies applied for E&E waste are investigated.It is found that India performs better in E&E intensity per service unit and employment potentials,while Switzerland performs better in occupational hazards and emissions of toxics.Recommendations to improve the existing E&E waste recycling situations and its implications to green building are also given.

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.

Kinetic studies of gold recovery from dilute aqueous solutions using Fe^(2+) chloride ions

The kinetics of Au3＋ chloride complex ions reduction using Fe2＋ chloride ions was investigated by stopped-flow method. The influence of initial concentrations of Au3＋ chloride ions, Fe2＋ ions, chloride ions, neutral salt （NaC104）, pH of the solution and temperature was investigated. Activation energy was determined to be 42.36 kJ/mol. Moreover, the kinetic equation was postulated. Obtained solid phase was analyzed using SEM techniques. Particles size varies in the range from 0.5 to 5 gm. It was shown that gold can be removed from the solution by the reduction ofAu3＋ chloride ions and filtration of precipitant.

Processing, Recovery and Analysis of Precious Metals Using Molecular Recogntion Technology

IBC Advanced Technologies' Molecular Recognition Technology(MRT) products,trade named SuperLig,selectively and rapidly bind with target metal ions to remove them from solution.The MRT process can produce a high purity separation product of maximum added value at low cost.In this paper,applications of MRT in the precious metals industry,including selective commercial separations involving Au,Pd,Pt,Rh,and Ru,are described and discussed.Application of MRT to the analytical determination of precious metals is presented.Potential use of MRT in recovering precious metals from end-of-life(EOL) products is discussed.

Atmospheric PCDD/Fs in Southeastern China

Air samples were collected simultaneously at Guiyu （an electronic waste recycling site）, three urban sites in Hong Kong and two urban sites in Guangzhou, southeast China on August 20, 2004 and January 24, 2005, respectively. Seventeen congeners of PCDD/Fs （polychlorinated dibenzo-p-dioxins dibenzofurans） were measured. The results showed that the concentration of PCDD/Fs in Guiyu was 6,721 fg/m3, which was 1.5 times of Guangzhou and 3.1 times of Hong Kong sites. TEQ （total toxic equivalent） of Guiyu, Guangzhou and Hong Kong air samples were 598, 202 and 137 fg I-TEQ/m3, respectively. A clear seasonal variation of PCDD/Fs in the air was found in both Guangzhou and Hong Kong sites. The concentration of 2,3,7,8-TCDD （2,3,7,8-Tetrachlorodibenzodioxin） in Guiyu was 54 fg/m3, higher than the whole year standard of 30 fg/m3 imposed by USA （Indiana, Kansas and Washington）. This was primarily due to the incomplete combustion of e-wastes （e.g., plastic chips, wire insulations, PVC （polyvinyl chloride polymer） materials and metal scraps）.

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.

Products Made from Nonmetallic Materials Reclaimed from Waste Printed Circuit Boards

Printed circuit boards （PCBs） are in all electronic equipment, so with the sharp increase of electronic waste, the recovery of PCB components has become a critical research field. This paper presents a study of the reclaimation and reuse of nonmetallic materials recovered from waste PCBs. Mechanical processes, such as crushing, milling, and separation, were used to process waste PCBs. Nonmetallic materials in the PCBs were separated using density-based separation with separation rates in excess of 95%. The recovered nonmetals were used to make models, construction materials, composite boards, sewer grates, and amusement park boats. The PCB nonmetal products have better mechanical characteristics and durability than traditional materials and fillers. The flexural strength of the PCB nonmetallic material composite boards is 30% greater than that of standard products. Products derived from PCB waste processing have been brought into industrial production. The study shows that PCB nonmetals can be reused in profitable and environmentally friendly ways.

Consumption of rice and fish in an electronic waste recycling area contributes significantly to total daily intake of mercury

Mercury is a global pollutant due to its widespread use,emission,and long-range transport（Blum,2013;Pacyna et al.,2010）.It is considered a priority pollutant due to its neurological toxicity,persistence,and bioaccumulation（Pacyna et al.,2010;Sharma et al.,2015）.Mercury pollution can occur when products that contain mercury are improperly disposed of and mercury is released into the air,water,and soil（Zhang and Wong,2007）.An estimated 22%of the annual world usage of mercury is in electrical equipment such as batteries,thermometers,and discharge lamps,and electronic devices such as monitors and

Electrochemistry during efficient copper recovery from complex electronic waste using ammonia based solutions

Leaching selectivity during metal recovery from complex electronic waste using a hydrochemical process is always one of the generic issues. It was recently improved by using ammonia-based leaching process, specifically for electronic waste enriched with copper. This research proposes electrodeposition as the subsequent approach to effectively recover copper from the solutions after selective leaching of the electronic waste and focuses on recognising the electrochemical features of copper recovery. The electrochemical reactions were investigated by considering the effects of copper concentration, scan rate and ammonium salts. The diffusion coefficient, charge transfer coefficient and heterogeneous reaction constant of the electrodeposition process were evaluated in accordance with different solution conditions. The results have shown that electrochemical recovery of copper from ammonia- based solution under the conditions of selective electronic waste treatment is charge transfer controlled and provide bases to correlate the kinetic parameters with further optimisation of the selective recovery of metals from electronic waste.