Colloid-facilitated release of polybrominated diphenyl ethers at an e-waste recycling site: evidence from undisturbed soil core leaching experiments

Polybrominated diphenyl ethers (PBDEs), a class of persistent organic pollutants, have been frequently detected in soil at e-waste recycling sites. However, the key factors controlling the transport of PBDEs from surface soil to the vadose zone and groundwater are unclear. Here, colloid-enhanced leaching of PBDEs from undisturbed soil cores collected at an e-waste recycling site in Tianjin, China, is reported. Spatially heterogeneous release of colloids and PBDEs was observed in all the tested soil cores under chemical and hydrodynamic perturbations, indicating the presence of preferential flow paths. Colloid concentration in the effluent significantly increased as ionic strength decreased (from 10 to 0.01 mmol/L), probably due to the stronger electrostatic repulsion between colloidal particles and the soil matrix at lower ionic strength. In contrast, colloid mobilization was not significantly affected by the changes in pH of the influent (from 4.0 to 10.0) and flow rate (from a Darcy velocity of 1.5 to 6.0 cm/h). The concentrations of 2,2′,3,3′,4,4′,5,5′,6,6′-decabromodiphenyl ether (BDE-209), the predominant PBDE congener at the site, detected in the leachate (ranging from 1.09 to 3.43 ng/L) were much lower than previously reported results from packed column leaching tests, and were positively correlated with colloid concentrations. This indicates that remobilization of colloids at e-waste recycling sites can promote the leaching and downward migration of PBDEs from surface soil. The findings highlight the potential risk of surface soil PBDE contamination to groundwater quality and call for further understanding of colloid-facilitated transport for predicting the fate of PBDEs at e-waste recycling sites.

Integrating the valence theory and the norm activation theory to understand consumers’ e-waste recycling intention

Electrical and electronic waste(e-waste)is a growing challenge,matching the widespread boom in the use of information and communication technology.Opposite to an alarming increasing amount of e-waste,a low rate of consumer engagement in ensuring the proper disposal of such materials intensifies the pressure on the exist‐ing e-waste crisis.To deal with this thorny problem,it is of great interest to grasp consumers’disposal and re‐cycling behavioral intentions.Therefore,this study attempts to understand complementary perspectives around consumers’e-waste recycling intention based on the integration of the valence theory and the norm activation theory.Four data mining models using classification and prediction-based algorithms,namely Chi squared automatic interaction detector(CHAID),Neural network,Discriminant analysis,and Quick,unbiased,efficient statistical tree(QUEST),were employed to analyze a set of the 398 data collected in Vietnam.The re‐sults revealed that the social support value is by far the most critical predictor,followed by the utilitarian value,task difficulty,and monetary risk.It is also noteworthy that the awareness of consequences,education background,the ascription of responsibility,and age were also ranked as critical affecting factors.The lowest influential predictors found in this study were income and gender.In addition,a comparison was made in terms of the classification performance of the four utilized data mining techniques.Based on several evalua‐tion measurements(confusion matrix,accuracy,precision,recall,specificity,F-measure,ROC curve,and AUC),the aggregated results suggested that CHAID and Neural network performed the best.The findings of this research are expected to assist policymakers and future researchers in updating all information surround‐ing consumer behavioral intention-related topics focusing on e-waste.Furthermore,the adoption of data min‐ing algorithms for prediction is another insight of this study,which may shed the light on data mining applica‐tions in such environmental studies in the future.

Comparative Study on the E-waste Recycling Systems in Japan and China

This study aims to identify processes, current situations and issues of recycling systems for four home appliances, namely, air conditioners, television receivers, refrigerators, and washing machines, among e-wastes in China and Japan for understanding and comparison of their characteristics. In accordance with results of a literature search, review of information disclosed online, and questionnaire survey conducted, the findings of this study are summarized in the following two points： （1） The results show that in Japan most of the home appliances mentioned above have been collected through home appliance recycling tickets, resulting in an issue of ＂requiring some effort＂ in treatment and recycling stages, and most plants have contracted out their e-waste recycling; （2） It is found out that advantages of the recycling system in Japan include easiness to monitor concrete data and thorough environmental friendliness ensured while its disadvantages include illegal dumping and export. It becomes apparent that advantages of the recycling system in China include a high reuse rate, low treatment cost, and fewer illegal dumping while its disadvantages include less safe reused products, environmental pollution caused by e-waste treatment, illegal import and difficulty in obtaining data.

Developing an Extended Theory of Planned Behavior Model for Small E-Waste Recycling:An Analysis of Consumer Behavior Determinants

WEEE(Waste Electrical and Electronic Equipment),also called e-waste,has become the world’s fastest-growing waste stream but only has a 17.4%recycling rate according to the Global E-waste Monitor 2020.The collection rate for sWEEE(Small WEEE),e.g.,used mobile phones,is even lower than 10%due to stockpiling at home and improper disposal via the general waste or private informal channels.The purpose of this paper was to(a)review how the TPB(Theory of Planned Behavior)was applied in the literature related to consumer behavioral intention for WEEE recycling and determine the most significant TPB predictors by comparing their standardized influence coefficients across various studies,and(b)identify additional behavior determinants specific to sWEEE recycling and thus develop a new TPB-sWEEE theoretical framework by integrating the TPB model with these new determinants in order to improve the predictability of consumers’sWEEE recycling behavioral intention.This paper reviewed over 30 peer-reviewed studies from Scopus and high impact factor journals and led to the following three key findings:(a)More variables of recycling behavioral intention determinants such as the size of WEEE need to be considered;(b)Eight sWEEE-specific behavioral determinants have been identified and included in the newly developed TPB-sWEEE model,including consumers’Sentimental Attachment,Data Security Concern,Economic Incentives,and How-to Knowledge;(c)For some sWEEE-specific determinants,their extent of influence differs across various regions and countries.This paper contributes to the sWEEE-specific consumer recycling behavior theoretical framework to fill the existing gap in the literature and provides recommendations through the new model for research-based behavioral intervention strategies and policy designs globally.

Thoughts on e-waste recycling

This paper summarizes the situation of e-waste recycling in China, points out several key problems, identify the causes and draw lessons and experiences abroad about e-waste management, propose systematic suggestions from the production side, the recovery side, consumers side, government departments and thelegislation.

Current State, Shortcomings, and Strategies to Improve China’s Waste Recycling Network: Optimization of Regional Site Selection for Waste Disposal Systems Based on Supply Chain Management

Based on the basic supply chain model,the status quo of waste recycling in China is examined by analyzing and comparing the changes in the waste recycling network and the problems of siting in relation to China’s waste disposal system.

Knowledge, Practices, and Environmental and Occupational Health Risks Associated with Electronic Waste Recycling in Cotonou, Benin

Objective: The e-waste recycling is increasing worldwide, yet there remain outstanding environmental and occupational health concerns. Most research conducted on e-waste recycling has focused on only few countries (e.g., China, Ghana), thus there is a need to increase understanding of e-waste workers’ (recyclers’) knowledge and practices in other locations, that is purpose of this study. Methods: In a cross-sectional study conducted in Cotonou, Benin, 45 e-waste recyclers were interviewed from September to November 2018. Survey data was collected concerning their demographics, professional practices, and knowledge of occupational and environmental risks associated with e-waste recycling. Results: Most participants reported the following methods of material recovery of electronic items in declining orders: dismantling (97.8%) > sorting (91.1%) > incinerating (88.9%). Only 44.2% of the recyclers reported wearing ≥ 1 piece of personal protective equipment (PPE). More than 90% of e-waste workers noted that they disposed the e-waste in natural sites. About half, 46.7% believed that e-waste can pollute water and 71.1% considered that it can pollute air and soil. Recyclers reported several diseases including respiratory (67.4%), heart (62.8%), eye (65.1%), kidney (41.9%) and cancers (30.2%) could be linked to their work, respectively. Interestingly, we also found associations between the number of electronic items dismantled per month and self-report symptoms from the e-waste recyclers such as finding blood in urine and stool, wounds, dizziness, and itchy skin. Our results also indicated associations between the number of hours worked per day and blood in urine, dizziness, itchy skin and airway obstruction. Conclusion: To our knowledge this is the first study to interview e-waste workers in Benin. Doing this increase understanding of their work practices and knowledge to help inform intervention and prevention activities.

Evaluating the treatment of E-waste──a case study of discarded refrigerators

Disassembly and recycling of E-waste creates a series of environmental problems. The selection of a technologically reliable, environmentally friendly, economically affordable and socially acceptable recycling technology for E-waste is a significant question. This study establishes a Monte-Carlo mathematical model of cost minimization, given the constraints of environmentally sound handling of the e-waste, in the context of Crystal Ball risk assessment and evaluation software. By following the streams of the different treatment processes, which consist of various technologies including disassembly, recycling and disposal, the econom-ics of various possibilities were identified and the optimal recycling technology proposed. The key factors of the proposed scenarios were determined by using sensitivity analysis. The results of this study show that, for discarded refrigerators, the operating life span plays the key role. The model supports maintenance and resale of the short lived refrigerators. For the longer lived refrigerators material recycling is recommended by the model. Sensitivity analysis shows that purchase cost, plastic sale price, condenser sale price and disassembly costs are the main effects. This study provides a significant technical support for policy making in E-waste management.

Review: Current Status of Recycling of Waste Printed Circuit Boards in India

Printed Circuit Boards (PCBs) are an integral part of any electronic equipment. The growth of e-waste as end-of-life electronic equipments at an exponential rate is producing large quantities of discarded PCBs. In India, current recycling and processing of PCBs is managed almost entirely by the informal sector or the unskilled labor (95%). The crude recycling activities cause irreversible health and environmental hazards and the loss of valuable materials due to the poor recovery of base and precious metals. With the disclosures of the recycling being done by unskilled labor, alternative recycling strategies are being sought with the aim of higher recovery of materials in an environment friendly manner. There is an urgent need to establish effective and efficient methods for recycling the metals presented in the waste PCBs. In this study, the existing methods practiced for recycling of waste PCBs in India and the management strategies for handling them are assessed.

Recycling valuable cobalt from spent lithium ion batteries for controllably designing a novel sea-urchin-like cobalt nitride-graphene hybrid catalyst: Towards efficient overall water splitting

Along with the continuous consumption in lithium-ion batteries (LIBs), the price of cobalt is inevitably going up in recent years. Therefore, recycling valuable Co element from spent devices, and boosting its service efficiency are becoming two indispensable approaches to promote the utilization of Co in various energy conversion/storage devices. Herein, we realize the recovery of Co from spent LIBs and synthesize a three–dimensional (3D) sea-urchin-like cobalt nitride composite material (labeled as CoN-Gr-2), which is used as a bi-functional catalyst for water splitting. Benefiting from the intrinsic high conductivity, larger surface area and unique 3D sea–urchin–like architecture, CoN-Gr-2 shows an excellent electron transfer efficiency, highly exposed active sites as well as the superior mass transport capacity. The CoN-Gr-2 catalyst exhibits low overpotentials of 128.9 mV and 280 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which are comparable to the commercial 20 wt% Pt/C and RuO_(2) catalysts. Moreover, when adopting CoN-Gr-2 as both anode and cathode materials for overall water splitting (in 1.0 M KOH electrolyte), the assembled cell achieves a current density of 10 mA cm^(−2) at 1.61 V, which almost close to that of Pt/C||RuO_(2) benchmark (1.60 V), demonstrating its superior water-splitting efficiency. Meanwhile, the CoN catalysts exhibit strong chemical interaction with the Gr support, suppressing the aggregation of CoN catalysts and maintains their high activity during HER and OER reactions. So, the cell exhibits a high current retention of 97.3% after 40 h. This work successfully develops an industrial chain from recycling Co wastes in spent energy devices to controllably designing 3D sea-urchin-like CoN-Gr with high water splitting efficiency. Therefore, it could further promote the efficient utilization of valuable Co element in various energy devices.

Electrical and electronic waste (e-waste) recycling and management strategies in South Asian region: a systematic review from Sri Lankan context

Electrical and electronic waste(e-waste)has become a global crisis.Managing this ever-growing problem has become very critical and yet challenging,especially in the South Asian region;otherwise,it may undermine the sustainability of development and growth of numerous industries.Hence,to explore the current context of e-waste management,recycling,and strategies in Sri Lanka,we conducted a systematic literature review process using peer-reviewed research articles retrieved from Google Scholar Database.We searched for articles containing keywords such as“e-waste”,“management strategies and recycling”,and“Sri Lanka”.We screened out papers(n=20)selected from papers(n=327)initially retrieved over a 17 period of time(2005–2022).The analysis of the screened articles showed that the main challenges to successful e-waste management were a lack of management strategies,policies,and inadequate recycling practices as well as identifying the potential and opportunities to actively enhance the comprehensive awareness,collection,storage,proper disposal,and other e-waste management steps in Sri Lanka.Further,the study identified technological,financial,socio-economic,and institutional sectors as fundamental sectors to formulate a strategic plan for e-waste management.Also,the study suggests that enacting laws to practice and adopt e-waste management,establishing central command and management institutes to control all e-waste management bodies,providing financial assistance to informal e-waste collectors and recyclers,and introducing e-waste management to school curricula are some of the possible actions that can be taken along with enhancing the awareness of e-waste management.

基于人工蜂群算法的快递循环包装回收中心选址方法

近年来,快递循环包装的使用量越来越多,不仅消耗了大量成本,循环包装材料对环境造成的影响也越来越大。与此同时,对快递循环包装回收的整体规划却还不完善,回收工作还存在难度大、效率低的问题,给回收中心进行选址能够有效解决这一问题。因此本研究提出了一种快递循环包装回收中心选址的方法,以成本和碳排放为优化目标,采用人工蜂群算法(ABC)进行优化求解,并与其他优化算法进行了对比。经过实验验证,本研究提出的方法在优化速度和优化结果上都表现出了显著的优势,通过本研究提出的方法,可以有效地确定最佳的快递循环包装回收中心选址方案,从而降低循环包装回收过程中的成本和对环境的不良影响。在未来的研究中,可考虑更多社会影响因素,以促进循环包装回收的可持续发展。

沥青路面就地热再生混合料再生剂用量及级配优化

为提升再生沥青混合料级配、新沥青混合料掺量的准确性,保障再生沥青混合料的综合性能,从旧沥青混合料的沥青含量、回收沥青的性能、旧混合料的级配方面进行了深入剖析,采用骨架密实设计法设计了再生沥青混合料级配,试验了新沥青混合料的用量,最后开展了再生沥青混合料高温、低温、水稳定性试验。通过就地热再生沥青混合料的优化设计,确认再生沥青混合料的合成级配宜采用骨架密实型且较低空隙率的混合料,再生剂用量为旧沥青混合料质量的4%,混合料的高温、低温、水稳定性能均与热拌沥青混合料性能相当,最后提出了施工过程中级配变异时应及时采取变异策略。

新型乳化再生剂制备与性能测试及路面应用效益分析

针对传统沥青再生剂对沥青改性效果较差的问题,制备一种新型乳化再生剂,并对乳化再生剂再生后沥青的性能进行研究。试验结果表明,经过质量分数为8%的乳化再生剂处理的老化沥青,在粘度、针入度和延度方面均能达到新沥青标准,低温抗裂性能和弹性性能均得到很好的改善,各项路用性能均满足JTG D50-2017标准,可以在路面工程中发挥作用。通过就地热再生技术使用再生后沥青对老化路面进行修复,道路各项性能均满足JTG 3450—2019规范值,具备较好的平整度、抗滑性能和抗渗性能,满足路面行车要求。

渤海绥中X油田修井机升级改造设计及现场应用

渤海油田开发进入中后期,部分老油田需要设计实施调整井来挖潜剩余油。绥中X油田F平台由于HXJ60修井机能力不足且服役时间较长,不能满足侧钻作业的要求,需升级改造为HXJ180修井机。经论证,确定了修井机升级改造采纳置换、回迁方案,改造设计中主要包括对原修井机实施拆卸回收,对新修井机实施安装调试等方案内容。现场应用表明,升级改造后的HXJ180修井机验收合格,各项性能指标均能达到相关标准,具备了实施调整井作业的能力,为油藏后期开发提供了保障。

Airborne PCDD/Fs in two e-waste recycling regions after stricter environmental regulations

Since the 2010 s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling activities. In this study, ambient air and indoor dust near different kinds of e-waste recycling processes were collected in Guiyu and Qingyuan to investigate the pollution status of particles and polychlorinated dibenzo-pdioxins and furans（PCDD/Fs） after stricter environmental regulations. PM_（2.5） and PCDD/Fs both showed significantly reduced levels in the two regions compared with the documented data. The congener distribution and principal component analysis results also confirmed the significant differences between the current PCDD/Fs pollution characterizations and the historical ones. The estimated total intake doses via air inhalation and dust ingestion of children in the recycling region of Guiyu ranged from 10 to 32 pg TEQ/（kg·day）, which far exceeded the tolerable daily intake（TDI） limit（1–4 pg TEQ/（kg·day）. Although the measurements showed a significant reduction of the release of PCDD/Fs, the pollution status was still considered severe in Guiyu town after stricter regulations were implemented.

Toys, Décor, and More: Evidence of Hazardous Electronic Waste Recycled into New Consumer Products

Hazardous chemicals used in electronic and electrical consumer products can re-enter commerce when these products are recycled. The objectives of this study were to 1) identify the possible sources of unexpected chemicals and elements in consumer products, including the use of recycled E-waste plastics and 2) demonstrate bromine detection with nondestructive spectroscopy as an indicator of brominated flame retardants contaminating new products via recycled waste streams. More than 1500 consumer products of diverse types purchased in 2012-2014 were examined using X-ray fluorescence spectroscopy for correlations between bromine and other elements. New electronic products were much more likely than new non-electronics to contain greater than 1000 ppm bromine, consistent with intentionally added flame retardants, while non- electronic products were more likely to contain between 5 and 100 ppm bromine, suggesting unintentional contamination. A typical suite of elements present in E-waste was found in a majority of plastic products. Two product categories, vinyl floor tiles and beaded necklaces/garlands, were explored in more detail. Specific flame retardant chemicals in bead samples were identified by mass spectrometry and their distribution in beads was studied using scanning electron microscopy and energy dispersive spectroscopy. Five brominated chemicals typically used as flame retardants, including BDE-209, were identified in 50 of 50 Mardi Gras beads analyzed.

基于K-means聚类算法与重心法的故障共享单车回收中心选址优化

共享单车已日渐成为人们短途出行的重要交通工具,但共享单车市场一贯采用“重投放,轻维护”的发展模式,而共享单车使用中的正常损耗及人为破坏等造成的故障车数量却十分庞大,对其回收修复或报废的任务繁重,这也成了共享单车市场逆向物流亟待解决的难题。该文立足武汉共享单车市场,通过对故障共享单车报废点的聚类分析,基于运输成本导向,使用重心法探寻回收中心最佳选址点,以解决故障共享单车回收成本和效率问题。对模型的模拟验证表明,优化后的回收中心选址点不仅能降低故障共享单车回收成本,而且相比武汉市现有的三个分布较远的回收中心,其总体运营成本更低,故障共享单车回收效率更高,便于共享单车的分区域运营管理。事实证明,基于K-means聚类算法与重心法确定回收中心选址问题不仅操作简单,可行性高,而且方便快捷,相较于现实中单一考虑成本等的选址方式,此模型更能兼顾多方面因素,优势明显。基于K-means聚类算法与重心法来确定回收中心选址,适用于城市的各个区域,选点精确又方便高效,模型具有较强的实用性。

某高速公路服务区餐厨垃圾就地资源化技术研究与示范

针对高速公路服务区地域分散、餐厨垃圾产生量小的特点,采用就地资源化技术开发出一套高效环保、绿色节能、产出优质的餐厨垃圾智能一体化处理设备并进行示范。该技术采用绿色循环理念,融合微生物一体化设备及云平台管理,产出有机肥基质及毛油,减量率达85%以上,运行成本约为130元/t,成规模后单位产品经济附加值约为40元/t。该技术的成功示范每年可有效处理该高速服务区餐厨垃圾182.5 t,实现了餐厨垃圾就地无害化处理和资源化利用,可在我国具有分散性、不便集中处理的餐厨垃圾处理市场进行复制推广。

沥青路面就地热再生施工工艺及质量评价研究

为了提升城市道路再生沥青路面施工水平,文章以东莞市元美东路为研究对象,探讨了旧沥青路面加热、翻挖、再生剂喷洒、再生沥青混合料的摊铺和碾压、接缝处理等施工工艺要点,并在再生沥青路面施工完成后制订检测方案,以压实度、平整度作为指标来评价其施工质量。