E-Waste Unplugged: Reviewing Impacts, Valorization Strategies and Regulatory Frontiers for Efficient E-Waste Management

Abstract

Augmented consumerism has propelled electronic innovation, leading to unprecedented growth in e-waste. Mishandling of e-waste poses environmental and human health hazards that necessitate a review of existing technologies and regulatory frameworks for effective e-waste management. Over the years, advancements in e-waste treatment technologies have addressed challenges uncovered in conventional e-waste treatment methods. This review comprehensively discusses valorization, regulations, and the environmental and health hazards imposed by e-waste mismanagement. The review adopted the novel VIRE framework to justify the research question and followed PRISMA analysis to filter the research basket. This study highlights that progressive policy frameworks are less efficient until inhibiting factors for successful implementation are addressed, especially in developing countries. The informal sector dominates in impeding the successful implementation of e-waste regulations, requiring integration with the formal sector as an initiative to reduce unlawful e-waste handling. Moreover, e-waste holds significant potential for economic value through precious metal recovery. An integrated approach of thermal techniques followed by bioleaching could be a cost-effective alternative for enhanced metal recovery from e-waste. There exists ample opportunity for further advancement in treatment technologies through the integration of discrete techniques, reframing regulatory frameworks to minimize unauthorized processing, and cooperative international agreements for collective action on sustainable e-waste management.

1. Introduction

The advancement of modern lifestyles has driven the development of futuristic and smart devices aimed at enhancing daily convenience. Electrical and electronic equipment are vital for upscaling life standards and uplifting societal status. Consequently, development in this sector, fueled by innovation in advanced materials, polymers, synthetic organic materials, etc., has significantly improved the quality of products and their efficiency [1]. Over the decades, population increase and rapid industrialization have significantly heightened the production demand for such equipment globally [2]. Consequently, waste electronic and electric equipment (WEEE), or e-waste, has increased considerably, and it is expected to further rise at an unprecedented rate in the upcoming years. For instance, nearly 53.6 million tons (MTs) of e-waste was generated worldwide, which was ~20% more than the e-waste produced 5 years back [1]. According to the latest statistics from the United Nations Institute for Training and Research (UNITAR) under the Sustainable Cycles (SCYCLE) program, a staggering 62 MTs of e-waste was generated in 2022—an 82% increase compared to 2010 levels. This figure is projected to rise by a further 32%, surpassing 82 MTs by 2030 [3]. Correspondingly, the E-waste management market sector is climbing and is estimated to grow at a CAGR of 6.6% from 2024 to 2030, making the E-waste management sector one of the fastest-growing sectors from a market point of view [4]. In accordance with the International Criminal Police Organization (INTERPOL), the market value of e-waste produced is roughly 21 to 25 billion dollars per annum, according to the estimated value per ton of e-waste as 500 dollars [5]. Although the market for electronic and electric devices continues to expand rapidly, the lifespan and replacement cycle of these devices are steadily declining due to rapid technological advancements [1]. For example, the average replacement period for personal computers and central processing units (PC-CPUs) has decreased from 4 years to 2.5 years between 1997 and 2015, driven by continuous innovation and upgrades [6].

The entire e-waste domain comprises a variety of electronic and electrical equipment covering domestic appliances (washing machines, freezers, refrigerators, televisions, etc.), information and communication technology (ICT) devices (radio, mobile/cell phones, computer monitors, network system hardware, small satellite systems, etc.), lighting equipment (tungsten bulbs, compact fluorescent lamp (CFL), light-emitting diode (LED), etc.), monitoring devices (CCTV cameras), and other consumer electronic products [7,8]. These devices function by using vital components such as batteries, wires, cable wires with coatings, printed circuit boards (PCBs), synthetic polymer covers, cathode ray tubes (CRTs), energy storage components, semiconductors, diodes, capacitors, soldering material, end-of-life vehicles (ELVs), etc., [1,9,10]. Most electronic devices are based on PCBs, which control the signal processing. Global production of PCBs is rising by about 8.7% yearly, with increases of 11% and 14.5% in Southeast Asia and China, respectively [11]. With the current emphasis on shifting from conventional energy sources and the promotion of electric vehicles, the production of electric and electronic equipment is expected to rise considerably in the near future [12]. Several studies have shown that increased demand for electric vehicles has directly influenced the production demand of end-of-life batteries and, consequently, lithium (Li) metal [13]. Further, developing countries target to promote the use of energy-efficient lights such as LEDs or CFLs to meet energy budgets, thereby again reinforcing the enhancement in the production of such devices [14]. Depending on the source of e-waste, metal contents vary, thereby differentiating their post-recovery economic values. For example, household e-waste is inferior in precious metals to that of e-waste from the telecommunications sector. Metals found in e-waste are generally classified as precious and toxic metals depending on their fate and influence. In general, a typical composition of e-waste includes metals (60%), plastics (15%), screens (12%), metal-plastic mix (5%), pollutants (3%), circuit boards (2%), cables (2%) and other components (1%) [15]. While electronic devices indeed enhance human convenience and comfort, their viability remains a complex question—especially when considering their high production rates, long-term environmental and health impacts, and the widespread mismanagement of the resulting waste.

Understanding the challenges imposed by e-waste is vital in the current era of adopting sustainable development goals (SDGs). The components required for manufacturing electrical and electronic equipment are mostly developed using synthetic organic polymers, heavy metals, rare earth elements, flammable materials, and other recalcitrant elements [16]. Due to the presence of recalcitrant complex organics, heavy metals, and other persistent elements and their harmful impact on human health, e-waste is classified as hazardous waste. In addition, e-waste contains plentiful toxins such as metals (Pb, Cd, Hg, Ni, Cr, Li, Be, Zn, Mn, etc.), polycyclic aromatic hydrocarbons (PAHs), chloro-fluorocarbons (CFCs), flame retardants, new flame retardants (NFRs), polybrominated diphenyl ethers (PBDEs), polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), per- and poly-fluoroalkyl substances (PFAS), and others [17,18]. Since some of the electronic products involve the usage of precious metals and rare earth metals, e-waste also contains gold, silver, platinum, etc., and rare earth metals (neodymium, europium, terbium, etc.) [19]. Moreover, the plastic fraction in e-waste, such as acrylonitrile–butadiene–styrene (ABS), high-impact polystyrene (HIP), polycarbonate (PC), and polypropylene (PP), which are harmful to the ecosystem if not recovered, is also increasing because of manufacturing advancements [20]. All these constituents of e-waste impose serious threats to the environment and human health if not treated as per established protocols or not disposed of in an environmentally sound manner.

Systematic recovery of precious metals, plastics, glass, and synthetic polymers is transforming the e-waste stream into a valuable component of the ‘Waste to Resource’ paradigm. Plentiful quantities of precious metals are found in waste PCBs with a metallic composition of around 30%, and the rest are non-metals, including plastics, ceramics, and resins [21]. Waste PCBs comprise a high amount of copper (~20%) as the main metal component, which comprises 10–12 times more than that found in high-grade metal ores [22]. The heavy metals/metals/rare earth elements hold significant economic value; for example, regular gold content in e-waste typically ranges between 80 and 250 g/ton, which is substantially higher than the concentration found in most natural gold ores. Recovery of precious metals and rare earth elements could be critical for sustaining the recycling supply chain of e-waste. However, supervised recycling by a competent authority is essential to ensure environmentally sound treatment, secure landfilling of non-recoverable residues, and ban illegal trafficking of recovered materials [23]. Furthermore, systematic recycling of e-waste is vital for secondary resource extraction within the circular economy framework. Hence, appropriate legislation and strict supervision are mandatory for e-waste management units. Various countries have adopted rules derived from common conventions or have framed their own legislations for respective e-waste management and transboundary movement for processing and disposal. Developed countries have imposed strict regulations on e-waste movement and its illegal processing to protect against potential environmental contamination. However, in developing countries, laws are not effectively enforced to prevent e-waste mishandling, thereby the risk of environmental contamination and human health hazards persists [24]. E-waste generation followed unprecedented growth in various regions across the world, based on economic growth and policy enforcement in various countries. The Asia Pacific region, being immensely populated and leading among the fastest developing regions, produces extraordinary e-waste. More than 50 MTs of global e-waste generation was recorded in 2019 itself, out of which the Asia Pacific region alone accounts for ~25 MTs [15]. However, according to Forti et al. (2020) [25], many countries, including those in the Asia-Pacific region, are improperly managing e-waste, thus entailing the urgent need for more intelligent and sustainable approaches to the global production, consumption, management, and disposal of e-waste. In the era of digitization, India has progressed to become the world’s third-largest e-waste-producing country after China and the USA, generating more than 3.23 MTs of e-waste per year [26].

This state-of-the-art review critically discusses various aspects of e-waste including—addressing current status, perspectives, and challenges associated with e-waste; e-waste fundamentals, classification, detailed compilation of its composition (Section 3); the impact of e-waste associated contaminants (heavy metals and emerging contaminants) on human health and environment (Section 4), conventional and advanced E-waste treatment technologies (Section 5 and Section 6) and a comparative assessment of legislations based on e-waste handling and operations in various developed and developing countries, including transboundary movement and SDGs (Section 7). The conclusions and perspectives are discussed in Section 8. The entire workflow is depicted in Figure 1. The cardinal novelty of this study lies in encompassing diverse aforementioned aspects, inter-relationships, and recent developments in e-waste regulatory frameworks, which thoroughly provide collective insights on material and resource recovery coupled with existing laws around the globe. Despite the large volume of R&D conducted in the aforementioned areas of e-waste management, notably, there remains a lack of all-inclusive review. This article will assist R&D efforts in the installation and scale-up of e-waste treatment plants.

2. Methods: Review Structure Development

2.1. Research Question Development: VIRE Framework

The development of research questions in this review was structured using the VIRE framework, which warrants organized and concentrated inquiry. The VIRE model incorporates four essential components: Viewpoint (V), Issue (I), Restriction (R), and Evaluation (E). The Viewpoint (V) corresponds to the perspective of concerned stakeholders in the context of e-waste management; the Viewpoint includes both environmental sustainability and policy effectiveness. The Issue (I) centered around the core questions being addressed, such as environmental, health, economic, and regulatory challenges linked to haphazard e-waste handling and disposal. The Restriction (R) distinguishes the scope and perimeters of the review to sustain relevance and feasibility. This part was ensured by restricting the search for peer-reviewed journal publications between 2005 and 2024, focusing on e-waste impacts on the environment and human health, valorization technologies, and regulatory frameworks in both developed and developing countries. Further, the Evaluation (E) belongs to the critical appraisal of e-waste mismanagement, treatment techniques, and the practical implications of different regulatory interventions, as discussed in various sections. Based on the aforementioned structure, a tailored VIRE framework was adopted to organize the review systematically and represent research questions clearly. The customized VIRE framework stands for—Valorization (V), Impacts (I), Regulations (R), and Environment (E). In this review, research questions are explained through these components. Here, Valorization (V) discusses techno-economic approaches for resource recovery from e-waste; Impacts (I) addresses environmental and human health consequences imposed by e-waste; Regulations (R) encompasses policy and legal frameworks, and Environment (E) highlights the wider ecological context within which e-waste management strategies operate. This dual VIRE framework signifies a systematic approach for defining research questions that are precise, answerable, and meaningful, and hold the importance of addressing for building long-term perspectives in the advancement of e-waste management systems.

2.2. Review Structure Development

The review adopts a qualitative approach to explore and identify issues pertaining to e-waste in selected developing and developed countries, their respective regulatory frameworks, and treatment technologies for resource recovery. A deductive thematic approach was followed to narrow down the scope of the review. Initially, a comprehensive literature survey was conducted across various repositories, including Scopus, Web of Science, and Google Scholar, using appropriately developed strings using truncation (e.g., manag* for management), wildcards, and Boolean operators (AND, OR, NOT, etc.). Broad coverage of keywords including “e-waste”, “WEEE”, “e-waste management”, “e-waste recycling”, “e-waste regulatory framework”, “e-waste in developing countries”, “WEEE disposal methods”, etc., as mentioned in

Table 1. Literature search strategy across databases using strings and operators.

Database	Search String	Operators/Techniques Used
Scopus	(“E-waste” OR “Electronic waste” OR “WEEE”) AND (“management” OR “valorization” OR “recycling”) AND (“policy” OR “regulation”)	Boolean (AND, OR), Truncation (recycl*), Phrase search (“ “)
Web of Science	(“e-waste” OR “WEEE”) AND (“impact” OR “environmental burden”) AND (“recovery” OR “valorization”)	Boolean (AND, OR), Phrase search
Google Scholar	allintitle: (“E-waste management” AND “valorization” AND “regulatory framework”)	Boolean, Keyword matching

. Further, the search was limited by applying restrictions like document types to journal papers, peer-reviewed conference papers, book chapters, and institutional data articles, and the publication period from 2005 to 2025. The next phase of the review involved the selection of the final collection for detailed analysis via the removal of duplicate articles. For the removal of articles and establishing the eligibility criteria, expert opinion was taken from authors’ affiliated organizations and their collaborations, involving suggestions from 50 experts working in the field of environmental engineering, waste management, landfilling, disposal, policy establishment, environmental forensics, and municipal officers. The PRISMA flowchart depicts (Figure 2) the overall process followed for collecting literature and narrowing it down for detailed analysis.

3. Understanding the Sources, Composition, and Classification

3.1. Definition

E-waste refers to electrical and electronic equipment, either absolutely or partially thrown as garbage by individuals or bulk consumers, as well as the ones rejected from production, renovation, and repair procedures. In terms of its chemical and physical composition, E-waste is distinct from other types of waste; therefore, it necessitates a suitable disposal method. E-waste must be reused and recycled to prevent the loss of valuable materials to landfills or incinerators. Additionally, prior studies have shown that the disposal of e-waste in landfills or through incineration has significant negative impacts on the environment and human health [27].

3.2. Cardinal Sources of E-Waste

Electronic equipment, solar cells, and electric vehicles are major sources of e-waste. Although they aid in driving exponential expansion in the IT industry, automotive, and renewable energy sectors, thus contributing positively to the country’s economic performance. The introduction of new technologies to the market by both public and commercial sectors is leading to the replacement of outdated electronic items, hence escalating the generation of e-waste. Household appliances, small and large organizations, computer manufacturers, institutions, and many other sectors generate domestic e-waste. Households contribute the least compared to mobile phones and laptops. Interestingly, in several countries, the disposal of such products is prohibited, resulting in challenges related to electronic waste management. The increase in prohibited e-waste imports is attributed to reduced processing costs, decreased labor expenses, and insufficient enforcement of environmental regulations. There is no reliable method to quantify the generated e-waste since the total production and the volumes imported and exported to other countries remain unknown [27].

3.2.1. Households’ E-Waste

Considering that a smaller percentage of e-waste is produced at home, accurately quantifying total e-waste generation remains challenging. A study claims that household appliances such as computers, refrigerators, generators, and similar products do not make a substantial contribution to the output. Approximately 20–21% of other industries are accountable for the production of e-waste [28].

3.2.2. Organizational E-Waste

This sector includes government agencies, public and private enterprises, multinational corporations, etc., and is considered the primary contributor to e-waste generation. According to the report, they account for around 79% of all installed PCs, the greatest proportion across all industries. Approximately 1.38 million obsolete PCs are discarded annually by this sector and households [28].

3.2.3. E-Waste from Manufacturers and Retailers

Discarded electronic equipment and components are generated and managed in large part by manufacturers and sellers. Hazardous compounds, including lead, mercury, and cadmium, present in the waste stream pose a threat to health and the environment [28].

3.3. Processing of E-Waste

Pretreatment, final processing, and collection are the three main phases of e-waste recycling. Every stage is necessary for the recycling sector and metal recovery. The collection of E-waste is facilitated by appropriate government regulations, effective public awareness campaigns, and the provision of distinct collection facilities in public spaces. When functional electronic components are put back into the consumer supply chain, end-of-life components are sorted at the collection facility. One crucial step in the recycling process is preparing e-waste.

There is no precise method to quantify the generated e-waste since the total production and the volume of imports and exports to other countries remain unknown [29]. As depicted in Figure 3, e-waste is either formally collected or recycled, discarded as waste, or handled by self-employed individuals and waste companies for material recovery.

3.4. Categorization of Diverse E-Waste Streams

E-waste, or electronic waste, denotes discarded electrical and electronic equipment (EEE) that has reached the end of its functional lifespan. It comprises diverse materials, including metals, polymers, and hazardous substances. E-waste categorization may be based on various criteria, including equipment type, components, and materials. Large and small household appliances, consumer electronics and IT equipment, electrical and electronic tools, lighting equipment, medical devices, automated dispensers, and vending machines are the main categories [30] as shown in Figure 4.

3.5. Composition of E-Waste

E-waste is a heterogeneous mix of materials including metals, plastics, glass, and hazardous materials. The composition depends on the type of electronic device, the era of manufacturing, and the materials used. Broadly, the composition is divided into a few important categories:

3.5.1. Metals

Metals constitute a major portion of e-waste, containing both valuable and toxic elements:

• Precious metals: Circuit boards and connectors use gold (Au), silver (Ag), platinum (Pt), and palladium (Pd).
• Base metals [Cu, Al, Sn]: These materials are used for wiring, casings, and soldering, respectively.
• Heavy metals: Older components such as CRT monitors, batteries, and circuit boards contain Lead (Pb), Cadmium (Cd), and Mercury (Hg).

3.5.2. Plastics and Polymers

A significant portion of e-waste is made up of plastics, in components such as casings, insulation, and circuit board laminates. Common types include the following:

• Polyvinyl chloride (PVC): Used in cables and insulation.
• Acrylonitrile butadiene styrene (ABS): Used in keyboards and casings.
• Polycarbonate (PC) and Polypropylene (PP): Used in structural components.

3.5.3. Glass, Ceramics, and Silica

Glass is mainly found in display screens such as cathode-ray tubes (CRTs), liquid crystal displays (LCDs), and modern OLED displays. CRT screens contain high amounts of lead, making their disposal environmentally hazardous while silicon (Si) is a primary component in semiconductor chips, microprocessors, and integrated circuits. Other ceramic materials are commonly used for capacitors, resistors, and insulating parts.

3.5.4. Toxic and Hazardous Substances

Many components of e-waste contain hazardous substances, which can pose environmental and health risks if improperly disposed of. A few examples are mentioned below:

• Brominated flame retardants (BFRs): Used in circuit boards and plastic casings to reduce flammability but they can release toxic compounds when burned.
• Polychlorinated biphenyls (PCBs): Found in older transformers and capacitors; these have been banned in many countries due to their high toxicity.
• Chlorofluorocarbons (CFCs): Present in the cooling systems of old refrigerators and air conditioners, and are known to contribute to ozone layer depletion.

3.5.5. Batteries and Other Components

• Lithium-ion batteries: Used in laptops, smartphones, and power banks, and contain lithium (Li), cobalt (Co), and nickel (Ni).
• Nickel-cadmium (Ni-Cd) and lead-acid batteries: Older devices may still contain these batteries, which pose environmental hazards.
• Capacitors and resistors: Found in circuit boards, often containing rare earth elements.

4. Impact of E-Waste on Humans and Ecosystem

4.1. Effects on Human Health

Human health is the cardinal ecosystem sector that is negatively impacted by e-waste due to a lack of awareness and improper management [31]. E-waste management, especially in developing nations, primarily involves the informal sector and public participants, directly exposing people to potentially harmful materials found in e-waste. Such wastes comprise plentiful hazardous entities such as heavy metals (Pb, Ni, Cd, Hg, Cr, etc.), complex organic compounds—typically known as emerging contaminants including flame retardants, chloro-fluorocarbons (CFCs), polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs), polychlorinated bisphenols (PCBs) and poly-chlorinated dibenzo-p-dioxins and furans (PCDD/Fs) [24,25,32,33]. Although the treatment process of e-waste includes the recovery of precious metals, prolonged exposure to the aforementioned heavy metals could be hazardous to human health. Exposure to e-waste among people in the vicinity occurs through various complex pathways. Types and durations of exposure (direct or indirect) to E-waste, and their synergistic or additive effects, could impact human health [17,34]. However, it is problematic to determine the impact of exposure to an explicit e-waste-related substance in isolation. Workers residing in nearby e-waste processing sites could experience dermal infections and ingestion of toxic substances through contact with contaminated water, soil, air, or vegetation nearby [7]. Commonly observed diseases among people living near e-waste processing sites include asthma, neurological disorders, obesity, and a disordered digestive system [35].

Informal sectors in developing countries are often leniently monitored or audited by competent authorities, causing severe pollution in air, soil, and water bodies and harming the environment and, finally, human health in the long term [6,36,37,38]. Various studies have reported exposure to such toxic heavy metals and emerging contaminants in natural ecosystems and have even proved to be carcinogenic for humans [39,40]. Exposure to heavy metals, especially Pb, causes severe health impacts in preschool children contributing to increased mortality rates in recent years [41,42]. Long-term exposure to Pb from e-waste disposal sites can lead to brain tumors, abnormal brain growth in developing nuclei, and even sensory integration difficulties in young children [43].

Chemicals leaching out from e-waste can affect unborn children if pregnant women are exposed to in-utero contamination, leading to lymphocyte formation in the umbilical cord and epigenome [44]. They reported that heavy metals, if present in high concentrations, can cause irregular methylation of 79 genes in DNA, which are required for various biological processes such as ion binding, cell adhesion, embryonic morphogenesis, apoptosis, vital signaling pathways, and others [44,45,46]. Another important study demonstrated an increase in urinary metabolites of PAH in women, reduction in body weight, imbalanced body mass index (BMI), misoriented head circumference, and Apgar 1 score in newborn babies [47]. Various other investigations have demonstrated a wide range of health problems in individuals exposed to e-waste-derived contaminants such as heavy metals—Pb [41,43,44,48,49]. Cd [44,45,46,50,51]. Hg [46], Mn [44,52,53], Cr [45,53,54,55], PAHs [31,47,55,56]. PBDEs [36,57,58], PCBs [59,60,61,62], new flame retardants (NFRs) [63,64], as well as PFAS [18,65,66]. A detailed summary reflecting the adverse effects of toxic constituents of E-waste can be found in

Table 2. Impact of contaminants (heavy metals, persistent organic pollutants, emerging contaminants) released from haphazard processing of e-waste on human health.

S. No.	Contaminant	Component of E-Waste as Source	Health Effects	Reference(s)
1.	Lead (Pb)	Cathode ray tubes (CRTs) of TVs, computer monitors, light lamps, CFLs, circuit boards, and batteries.	Brain damage in children, mutated nervous system, damage to reproductive system, anemia, neurological disorders in adults and children, and kidney damage.	[41,43,44]
2.	Mercury (Hg)	Liquid-crystal display (LCD) screens for TVs and monitors, CRTs, Printed Circuit Boards (PCBs), temperature sensors, computer screens, and CFLs (~1–2 g per unit).	Brain damage, neurological disorders, Methylmercury disease (brain and spinal cord damage), Minamata disease, anemia, chronic neurological diseases (insomnia, cognitive dysfunction, and neuromuscular defects)	[46,67]
3.	Chromium (Cr, Cr (VI))	Anti-corrosive coating in metal bodies of electronic devices, floppies, CDs, Emerald green glass, pigmentation, and data tapes.	Highly toxic and carcinogenic metal, lung cancer (long exposure), eye damage, muscular contraction, causes Genotoxicity (DNA mutation, mutation of cells, and cancerous tumors), affects reproductive organs and endocrine functions.	[53,54,55]
4.	Nickel (Ni)	Power storage devices (batteries), anti-corrosive plating, electron gun in CRTs, electrical connectors, circuit breakers, Ni alloys (Nickel 270, NILO alloy, and NILOMAG alloy 77) in transistor and anode plates and shanks.	Skin diseases (Ni allergy or dermatitis), rashes/itching upon direct contact; Ni fumes cause lung fibrosis and respiratory cancers (long exposure); cardiovascular diseases, high blood pressure.	[51,53]
5.	Lithium (Li)	Lithium-ion batteries (phones, laptops, tablets, electric vehicles, etc.), Heart pacemakers, and electronic toys.	Inhalation via air is toxic, causing nausea, digestive system damage, fatigue, chemical burns, eye irritation, and corneal damage.	[67,68,69]
6.	Cadmium (Cd)	Batteries (Cd-Ni), rechargeable storage, stabilizers, pigment agents, solar cells, wireless power banks, and laptops.	Kidney damage, skeletal and respiratory system defects, fever, muscular pain, lung diseases (lung emphysema and cancer), and reproductive organ damage.	[44,45,46]
7.	Barium (Ba)	Used as Barium titanate (BaTiO3) in capacitors, and in transducers, optical devices, CRTs, and CFLs.	Paralysis upon long-term exposure affects heart rate, respiratory illness, cardio-muscular diseases, digestive system damage, and cardiac arrhythmias.	[34,70]
8.	Zinc (Zn)	Light-Emitting Diodes (LEDs), Batteries, solder joints, sensors, piezoelectric devices, conductive films, and varistors.	Diarrhea, copper deficiency, damage to the pancreas, respiratory illness, anemia, and neurological disorders.	[54,67,70]
9.	Beryllium (Be)	ICT equipment—cellular phones, computers, Power storage devices, X-ray machines, ceramic parts of electronic equipment.	Lung damage/cancer, Skin disease—Beryllium sensitization, chronic beryllium disease (CBD)—chest pain, cough, breathing loss, fatigue, weight loss, fever.	[71]
10.	Polycyclic aromatic hydrocarbons (PAHs)	Organic semiconductors, organic fuel cells, bio-photonics, bio-imaging devices, UV spectroscopy.	Highly toxic, immunotoxicogenic, carcinogenic, and teratogenic, causing kidney and liver damage, jaundice.	[31,44,56]
11.	Polychlorinated dibenzo-p-dioxins (PCDDs)	Smelting and soldering of electronic components having synthetic polymer bodies.	Skin diseases—Chloracne; immune system damage, reproductive diseases, endocrine disruption, cancerous, developmental abnormalities, gastrointestinal organ damage.	[72,73]
12.	New flame retardants (NFRs)	Plastic covers in electronic devices, PCBs, Wire insulation, Electric connectors, and components	Neurological damage in children, cancerous, endocrine damage, neurotoxicity, and reproductive organ damage.	[63,64]
13.	Per- and Polyfluoroalkyl Substances (PFAS)	Electrical components, semiconductors, thermal insulation applications, and water-resistant coatings in electronic devices.	Highly cancerous compounds—testicular and kidney cancers, Liver damage, immune system damage, and low birth weight.	[18,65,66]
14.	Polybrominated Diphenyl Ethers (PBDEs)	Used in flame-retardant wires and plastic coatings.	Thyroid, ovarian dysfunction, cancerous, affects glucose metabolism, affects neurodevelopment, and endocrine rupture.	[40,57,58]

.

4.2. Effects on Environmental Systems

The e-waste treatment and processing activities impose considerable risks for possible environmental pollution. Informal recycling of e-waste and precious heavy metals recovery from e-waste poses significant environmental risks as the release of toxic substances is highly susceptible [37,54,74]. Since e-waste contains a wide range of heavy metals, emerging contaminants of concern, and other hazardous substances that carry health risks, it is obligatory to prevent these chemicals from penetrating into environmental systems and prohibit their bioaugmentation into human bodies [65,73]. Despite such facts, achieving completely efficient recycling and environmentally sound disposal has been really challenging owing to leniency in legislation, law enforcement, personal interests of stakeholders, and lack of strict supervision, particularly in developing countries [23]. Thus, the dispersion of hazardous and toxic chemicals occurs, releasing them into environmental systems such as water, soil, and air. Such scenarios are frequently observed while e-waste recycling is carried out mostly by informal sectors in sub-standard infrastructure, residential complexes, and unregulated commercial units [65,68]. In such cases, e-waste is processed by hazardous processes including open burning, manual dissembling, smelting, pulverizing, acid dissolving, cyanide salt leaching, and mercury amalgamation, which release hazardous pollutants into natural ecosystems and cause degradation in the qualities of air, water and soil, groundwater contamination and pollutant bioaugmentation [17,50,71].

It is worth noting that most of the pollutants released from e-waste are persistent pollutants, non-biodegradable, and pertain to hazardous impacts when exposed to biological systems [18,64]. Contamination of environmental systems is directly linked to health hazards caused by pollutants released through the mismanagement of e-waste. Figure 5 consolidates the effects of the improper disposal of e-waste on the environment and human health.

Table 3. Concentrations of contaminants released from various global e-waste sites into different environmental systems and their reported hazards.

S. No.	Contaminant	Country	E-Waste Site(s)	Targeted Environmental System (Soil/Air/Water)	Contaminant Concentrations and/or Remarks	Reference(s)
1.	Heavy metals (Cu, Pb, Cr, Mn, Ni, Zn)	China	Six sites in Longtang, China (burning, dumping, acid-leaching, paddy field, farm field, reference sites)	Soil and water	In Burning and acid-leaching sites: Cd (>0.39 mg kg−1) & Cu (>1981 mg kg−1), exceeded permissible limits. Cd: 0.62 mg/kg; Cu: 329 mg/kg (Paddy field).	[75]
2.	As, Cu, Co, Cd, Cr, Ni, Fe, Zn, Pb, and Ba	India	E-waste dismantling sites at Chandigarh and Ludhiana, Punjab, India	Soil (sand, dust, dermal samples)	Soil concentrations: As: 39.98 mg/kg; Cr: 287.19 mg/kg; Cu: 14,543.4 mg/kg; Pb: 1615.8 mg/kg. Hazard index for soil: As = 1.69, Cr = 1.38, Cu = 4.5 and Pb = 5.82 and dust samples: Pb = 2.97. High concentrations of Cr, Pb, and Zn in dermal samples.	[76]
3.	Pb, Cr, Mn, Fe, Co, Ni, Cu, and Cd	India	E-waste site at Sangrampur, West Bengal	Soil	Pb: 125.86–577.64 ppm; Cr: 50.47–219.41 ppm; Mn: 1083.89–4674.92 ppm; Fe: 1238.33–12,987.56  ppm; Co: 33.43–49.04  ppm; Ni: 84.52–157.35 ppm; Cu: 505.58–1156.18  ppm; Cd: 17.37–178.97  ppm The non-carcinogenic risk for a child was more than for an adult. Carcinogenic risks: 6.1 × 10−7 (child); 1.57 × 10−7 (adult)	[77]
4.	Pb, Cd, Cr, Ni, As	Viet Nam	E-waste processing sites at Bui Village and Nhuan Trach Village, Northern Viet Nam	Soil, rice, and drinking water samples	Bui Village (highest concentration only): Soil: Pb = 460.43 mg/kg; cooked rice: Ni = 9.57 mg/kg; water: Ni = 2.55 μg/L Nhuan Trach Village: Soil: Cr = 35.75 mg/kg; Cooked rice: Ni = 2.21 mg/kg; Water: Ni = 4.13 μg/L	[78]
5.	Pb, Cu, Ni, Cr, and Mn	Bangladesh	Nimtoli and Elephant Road areas, Dhaka, Bangladesh	Dust and air samples	Health quotient (HQ) and hazard index (HI) for heavy metals: Severe range The geo-accumulation index (Igeo) for the analyzed heavy metals was moderate to severe range.	[79]
6.	Cr, Zn, Cd, Pb, Ni, As, Ba, Cu, Ge, Pb, Se, and Zn and Cu	Nigeria	Ibadan, Lagos, and Aba (major E-waste recycling cities in Nigeria)	Soil and dust samples	All analyzed heavy metals were found to exceed the limits of Nigerian standards. Cu: 9420 mg/kg; Zn: 4533 mg/kg; Pb: 3810 mg/kg	[41]
7.	Cu, As, Cd, Sb, and Pb	Ghana	Agbogbloshie site, Accra, Ghana	Soil samples	analyzed heavy metals were bio-accessible in the gastric and intestinal systems, posing a human health risk. Percentage of these metal(loid)s: - Cu: 1.3–60, As: 1.3–40, Cd: 4.2–67, Sb: 0.7–85, Pb: 4.1–57	[80]
8.	Heavy metals (Cu, Cr, Zn, As, Cd, Sb, Pb, Hg, V, Co, Au); PBDE, PAH	Ghana	Agbogbloshie sites (dismantling, reference, ICT dismantling, oil collection workshop, printer dismantling, CRT dismantling), Accra, Ghana	Soil and groundwater samples	Based on contamination factors and potential ecological risk coefficients, heavy metals were found in the ‘very high’ range, in both soil and groundwater. Recycling of CRT and ICT devices has resulted in an 85% reduction in heavy metals. Cu, Pd, Cd, Sb, and Au are considerably high in topsoil.	[16]
9.	PAHs	China	E-waste recycling site, Longtang, South China	Soil and Plant (shoots, roots) samples	PAH concentrations (soil): 133 to 626 ng/g PAH concentrations (plants): 96 to 388 ng/g (shoots) and 143 to 605 ng/g (roots) Daily intake of PHA through vegetables: 99 and 22 ng/kg/day	[81]
10.	PAHs, Heavy metals	India	Four Indian metropolitan cities: Delhi, Kolkata, Mumbai, Chennai	Dumpsite soil samples, E-waste sites	PAHs and copper (Cu) were dominant in E-waste sites. e.g., PAH concentration: (1259 ng/g-New Delhi, E-waste site) PAH concentration: (1029 ng/g-New Delhi, dumpsites)	[82]
11.	PBDEs	China	Taizhou City, Zhejiang Province, China	Air, crop, and soil samples	PBDEs concentration: 91.9 μg/kg (dry weight)—soil samples; 27.8–25.1 pg/m3 (air) and 664–1380 pg/g (crop samples)	[83]
12.	PBDEs	Vietnam	E-waste-processing site, Bui Dau, Hung Yen Province, northern Vietnam	Soil samples, river sediments	PBDEs concentration (soil): 37–9200 ng g−1 PBDEs concentration (sediments): 23–6800 ng g−1	[84]

reflects the concentrations of contaminants emitted from several e-waste sites into various environmental systems and their associated risks.

Various instances have been reported of soil and water contamination by e-waste disposal [16,75,76,77,78,85]. Soil contamination poses hazards through direct exposure or long-term transport of leached pollutants through soil strata [86]. Soil possesses a vital function in the hydrological cycle and acts as a filtration medium that retains water and permits it to enter groundwater based on soil characteristics such as porosity, morphology, and permeability [77,87]. If soil strata in the proximity of the e-waste processing site are permeable enough, groundwater contamination is most likely to occur due to the infiltration of persistent contaminants [73].

There are various studies available that report soil and groundwater contamination because of e-waste disposal. Recently, ref. [88] have reported a considerable increase in heavy metals (Al, Cu, Cd, Pb, and Zn) concentrations in soils of multiple places in Delhi, India, due to open processing of e-waste; they recommended phytoremediation as the best option for soil remediation. At these sites, major categories of e-waste included computers, TVs, mixer–grinders, freezers, refrigerators, washing machines, ACs, and mobile phones [88]. Apart from heavy metals and metalloids, organic pollutants (PAHs, PBDEs, PCBs, and chlorinated paraffins (CPs)) were also found in high concentrations in soil samples from the West African sites of Agbogbloshie (Ghana) and Kingtom (Sierra Leone) [89]. Indeed, ref. [89] observed elevated levels of organic pollutants and heavy metals (Cu, Pb, Ni, Cd, Ag, and Hg) due to e-waste contamination, particularly through burning, open disposal, and direct soil contamination. Burning of e-waste on the soil surface also impacts soil microorganisms and engineering properties of soil by affecting their physico-chemical properties, ultimately hampering crop yield and growth of native vegetation [90].

Leached contaminants from open e-waste dumps contaminate surface and groundwater sources. Numerous instances of contamination in aquatic environments, including groundwater and surface waters, have been reported, more frequently in developing countries [23,75,85,91,92,93]. In Thailand, water contamination due to open disposal of e-waste led to the bioaccumulation of heavy metals (Fe, Mn, Zn, Cu, Cr, Ni, As, Pb, Cd, and Hg) in surface waters, sediments, gastropods, and Khorat snail-eating turtle’s (Malayemys khoratensis) blood making it harmful for aquatic ecosystem and human health [87]. Recently, similar observations of heavy metal bioaccumulation in Atlantic killfish (Fundulus heteroclitus) due to e-waste leachate contamination were also reported [94]. In China, persistent organic pollutants (PAH and PBDE) released from e-waste were reported to co-exist in e-waste recycling sites and possess a considerable risk of contaminating groundwater [38]. Moreover, they also reported that phenanthrene is more soluble than BDE-209, which tends to adsorb onto soil organic matter.

The illegal burning of e-waste releases highly toxic pollutants into the open atmosphere. The informal sector of e-waste recycling in developing countries accounts for about 95% of total e-waste recycling, making it susceptible to the illegal burning of e-waste components [88]. Since the informal sector lacks law enforcement and strict supervision, precious metals are recovered by local recyclers through open burning, during which toxic heavy metals, PAHs, PCDDs, particulate matter (PM10, PM2.5), and other volatile organic compounds are released into the atmosphere [95]. The open burning of e-waste is recognized as a global concern and a vital factor affecting the population and environment, as air is the most significant medium for the transportation of contaminants across the continents [31,55,80]. However, burning cable wires for recovery of copper and other components from other WEEE products is often recommended due to ease of operation [80], yet controlled burning is mandatory to prevent unwanted pollutants.

It should be emphasized that uncontrolled open burning of e-waste in Northern Uttar Pradesh, India, impacted air quality by increasing PM10 and heavy metals concentrations in selected residential sites; hypoxemia and hypertension were observed as frequent health problems in habitants nearby [57]. Another study conducted in the Kano metropolis, Nigeria, demonstrated that among all the analyzed heavy metals (Cd, Cu, and Pb), Pb had the highest mean concentration of 0.0693 ppm in air samples, followed by 0.00525 ppm (Cu) and 0.0042 ppm (Cd) [31]. Further, ref. [95] analyzed temporal PM10 and PM2.5 concentrations from the 1 km periphery of Agbogbloshie e-waste site, central Accra, Ghana, and found that PM10 concentration (1-h average) near to source exceeded 2000 μg/m³ sometimes, which was in the range of 145–214 μg/m³ at upwind and downwind sites. The PM2.5 levels ranged from 31 to 88 μg/m³ in the same vicinity. In summary, e-waste recycling and disposal have a direct impact on environmental elements and are ultimately connected to human health and ecosystems.

5. Conventional E-Waste Processing Pathways

Traditional e-waste processing techniques aim to recover valuable resources and remove hazardous components. Conventional methods, however, pose significant risks to human health and the environment.

5.1. Collection and Sorting

Electronic devices are collected from homes, companies, and disposal facilities as part of the first step in the processing of e-waste [96]. Both formal (government-regulated) and informal (unregulated sectors, especially in low-income nations) collection mechanisms are possible and are in operation. Sorting is often performed by hand, with employees disassembling gadgets to find reusable parts and separating potentially dangerous items such as batteries and cathode-ray tubes (CRTs). E-waste management techniques can be voluntarily improved by setting goals, imposing penalties, or providing incentives to communities for collecting rubbish. All parties engaged in the collection and processing of e-waste should be required to provide periodic reports to a central body in order to improve the effectiveness and control of e-waste management. E-waste management transactions must be carried out with traceable bank accounts or cards to guarantee accountability and transparency. A central registry should be created and maintained to date in order to collect data and regularly monitor activity [25,97].

5.2. Mechanical Processing

Mechanical processing is a key step in e-waste recycling that involves size reduction and material separation. In the refining stage, mechanical procedures are usually used to shred or pulverize the different metals and minerals present in E-waste. Following size reduction, the materials are separated into specified output fractions according to their unique physical properties, including weight, size, shape, density, and electrical and magnetic properties. The most widely used sorting techniques include gravity separation (heavy media floating, water or ventilation tables, and sieving), eddy current separation (electric conductivity) of aluminum, and magnetic separation of ferrous elements. The final output streams include an aluminum fraction that is sent to aluminum smelters, a copper fraction that is sent to a copper smelter, a magnetic fraction that is sent to a steel facility for additional processing, a clean plastic fraction that is occasionally produced, and a fraction of non-recyclable waste. The components are usually extracted in their entirety [98].

Polymers and other organic compounds included in PCBs can be transformed into flammable gases using thermal energy. In some recycling facilities, this is currently one of the main energy sources. The recovery of plastic materials and other non-metallic components for different uses, however, has become more important in recent years. In order to preserve valuable metals, the physical recycling process seeks to recover nonmetallic materials in their original condition. Since the form, size, and size distribution of the particles determine how well they separate, the degree of liberation plays a crucial role in the physical separation process [99].

5.3. Metallurgical Treatment

Metallurgical techniques extract valuable metals from e-waste through various chemical and thermal methods [100].

5.3.1. Pyrometallurgy

Pyrometallurgical processing encompasses high-temperature gas-phase operations, drossing, sintering, melting, incineration, and smelting in a blast furnace or a plasma arc furnace. Refractory oxides and some metal oxides make up the slag phase that is created when the crushed leftovers are burned in a furnace or molten bath to remove polymers [101]. Pyrometallurgy is one of the most traditional approaches. The benefit of pyrometallurgy is that it can use any kind of electronic waste as an input, but controlling the product stream is challenging. During the smelting process, many metals are lost in the slag or the slurry because refining methods are not selective in nature. Additionally, dioxin generation and toxicity release are risks associated with pyrometallurgy, especially if an efficient off-gas treatment and a particle containment/filter system are not used [102].

5.3.2. Hydrometallurgy

The initial phases of hydrometallurgical processing involve a series of solid materials leached with acid or caustic. The solutions are subjected to various separation and purification procedures, such as ion exchange, solvent extraction, adsorption, and impurity precipitation, in order to isolate and concentrate on the target metals. To recover the metals, the solutions are then subjected to electrorefining, chemical reduction, or crystallization [103,104]. The process of recovering metals is challenging, as hydrometallurgical processes produce solutions that contain a variety of metals. Among the main techniques for recovering metals are copper electrowinning, solvent extraction using lixiviants, and the cementation of zinc granules and sodium borohydride. Despite these well-established procedures, including cementation, solvent extraction, and precipitate techniques, there are still several obstacles to overcome for recovering metals from the leached-PCB solution [102].

5.4. Landfilling

Landfilling is one of the oldest methods to dispose of diverse waste, and it is still the main disposal pathway in developing nations. The product is disposed of at landfill sites where it persists permanently. The polymers in electronic garbage decompose very slowly, particularly in arid environments, which commonly prevail in landfills. The extremely harmful compounds included in many components of E-waste may contaminate land and groundwater through leached heavy metals and toxic compounds. Recently, landfill-mined waste has been valorized via anaerobic digestion to generate biogas [105]; however, no studies have been reported for e-waste mined from landfills.

As seen in Figure 6, inappropriate disposal techniques, consisting of landfilling and uncontrolled dumping (if not within the circular economy framework), are among the factors that lead to air and water pollution, which in turn has a detrimental effect on human health. The contamination of soil and water by toxic compounds derived from e-waste causes long-term harm to the environment. A circular economy strategy, on the other hand, encourages the collection, recycling, and recovery of precious metals from discarded electronic devices. This environmentally responsible approach lessens the effect on the environment while simultaneously promoting resource efficiency and the recycling of electrical equipment.

5.5. Recycling vs. Recovery of Reusable E-Waste Components

E-waste encompasses both recyclable materials and reusable components, each offering various economic and environmental benefits. Recyclable materials include metals, plastics, and glass. A recent finding concluded that 1 metric ton of mobile phones can yield approximately 350 g of gold (~INR 2 million), 150 kg of copper (~INR 120,000), and 100 g of palladium (~INR 400,000) [106]. Plastics like ABS, HIPS, and PC, which contain around 20–25% of the total e-waste mass, can be mechanically separated and reused, though contamination reduces recovery efficiency to around 60–70% [107].

However, reusable constituents, including hard drives, RAM, CPUs, and screens, retain functional value. Studies estimate that up to 15% of e-waste contains components suitable for refurbishment or direct reuse, yet less than 10% is currently recovered in India [108]. For example, refurbished laptops and smartphones can be resold for INR 5000–15,000, offering a circular economy model that reduces material extraction and energy use. Efficient recovery demands customized techniques, such as mechanical shredding and hydrometallurgical extraction for recyclables, diagnostic testing, and reinventing infrastructure for reusables. Combining both streams could strategically maximize resource recovery, economic returns, environmental benefits, and sustainability outcomes in e-waste management systems, as mentioned in

Table 4. Description of efficient extraction methods for recovery of respective metals and corresponding environmental impact.

Material	Extraction Method	Efficiency	Environmental Impact
Gold, Palladium, Silver	Hydrometallurgy (aqua regia, cyanide leaching)	High (~95%)	Moderate; needs wastewater management
Copper, Aluminum	Pyrometallurgy (smelting)	High (~90%)	High emissions; energy-intensive
Plastic	Mechanical separation (shredding, density separation)	Medium (~60–70%)	Low environmental impact if sorted properly
Rare Earths	Ion exchange, bioleaching	Emerging	Environmentally safer, but lower yields currently

.

6. Advanced Treatment and Recovery Technologies

This section discusses various pathways to process and valorize e-waste, including biochemical and thermochemical technologies. A schematic (Figure 7) reflects these technologies along with metallurgical methods that are usually considered conventional.

6.1. Biochemical Pathway

A novel development in e-waste recovery is the deployment of biological methods to remove metals such as Au and Cu from steels. This new method breaks down the waste and metal ores using microorganisms. Metals from ores, concentrates, and wastes are transformed into soluble salts in liquid media via biological processes. Ore bioleaching is usually categorized as either “direct” or “indirect” bio-oxidation. Most of the research has been conducted on indirect bio-oxidation. Microorganisms supply chemical oxidants for these processes, according to the research findings. Bacteria such as Acidithiobacillus ferrooxidans, Leptospiral ferroxidase, and Acidithiobacillus thiooxidans remove metals from trash as depicted in Figure 8 [109]. The aforementioned bacteria are chemolithoautotrophic mesophilic cultures that depend on inorganic elements (SO₄²⁻ and Fe²⁺) for energy harvesting and require an adequate temperature (28–37 °C) and carbon dioxide for cell synthesis [110]. A bioleaching experimentation study on waste PCBs using Acidithiobacillus ferrooxidans demonstrated that this bacterial culture not only increases the Cu recovery but also prevents the development of inhibitory byproducts such as libethenite (Cu₂(PO₄)(OH)), which decelerates metal recovery [111]. In quantitative terms, the tenfold recovery of Cu (41 to 413 ppm) was recorded within 7 days of the bioleaching experiment. Mixed culture has higher bioleaching capacity than that of individual acidophilic chemolithotrophic bacteria and acidophilic heterotrophic bacteria [110]. Certain moderate thermophilic bacteria yielded higher rates of bioleaching than intense mesophiles. For instance, a bioleaching study by Ilyas et al. [112] shows that Al³⁺ (0.65 ± 0.08%), Cu²⁺ (1.88 ± 0.05%), Fe²⁺ (2.50 ± 0.07%), Pb²⁺ (27.0 ± 0.08%), Ni²⁺ (0.22 ± 0.05%), Sn²⁺ (74.0 ± 0.07%), and Zn²⁺ (0.10 ± 0.01%), can be recovered from the selected E-waste source using Sulfobacilllus thermosulfidooxidans and Thermoplasma acidophilum. In another study, Ilyas et al. [113]. Sulfobacillus thermosulfidooxidans consortia with Thermoplasma acidophilum and Sulfobacillus acidophilus were cultured at 45 °C and employed in e-waste for metal recovery analysis through bioleaching. Interestingly, Cu, Al, Ni, and Zn were, respectively, recovered by 85%, 75%, 80%, and 80% when Sulfobacillus thermosulfidooxidans and Thermoplasma acidophilum were utilized.

Metal recovery via biotechnology is considered one of the most promising methods. Major global corporations have expressed significant interest in bio-metallurgy, indicating its potential to be a major technological advancement in the materials and minerals industry. In recent years, there has been a growing number of studies focused on understanding the biochemical processes involved in metal treatment. Many metals, such as copper, nickel, cobalt, zinc, gold, and silver, are currently the subject of research and development [101].

6.2. Thermochemical Treatment

Thermal processing techniques such as incineration (complete combustion), pyrolysis (devolatilization), and gasification (partial oxidation) are employed to process diverse e-waste streams and recover resources from them. Recently, advanced thermochemical pathways such as thermal plasma-assisted technologies have also been explored, employing different plasma sources such as DC arc, microwave, radio frequency, etc., to retrieve metals from e-waste [36]. Thermal cracking can also be employed to valorize plastics extracted from e-waste [114].

6.2.1. Incineration

Incineration and combustion are the burning of waste with an ample supply of oxygen or air. A thin coating of copper foil, which is laminated on motherboards is removed using the pit burning technique. This technique is employed after the separation of the remaining components. The copper, which contains some carbon impurities, is transferred to another recycling facility once the ash has been rinsed away. The defective condensers and integrated circuit chips, which have no resale market, are burned in small enclosures with chimneys to extract the metallic components [27,115].

Incineration, as opposed to smelting, does not result in the development of melts, particularly oxide ones such as slags. When treating electronic waste with high concentrations of valuable metals on a small scale for subsequent hydrometallurgical processing, this method proves advantageous. On the laboratory scale, stationary fluidized beds have also been assessed for the incineration of electronic trash, although conventional rotating furnaces seem to be most useful in such processing. The samples of PCBs were heated to 840 to 850 °C with 6.2 vol% oxygen for 3 min, resulting in approximately 21% of weight decrease. Incineration produced a brittle compound that could be processed further chemically or mechanically [116]. The incineration of e-waste has been practiced in various ways, including rotary furnaces and static fluidized beds [117]. Woynarowska et al. [118] conducted incineration of PCBs at 840–850 °C for 3 min and at 6.2 vol% of oxygen, leading to 21% of original material loss and resulting post-incineration substance as brittle, which has potential for chemical and mechanical processing. Further, this post-incineration product was subjected to a leaching test, which led to 99.6% and 97% recovery of copper and silver, respectively. In the case of incineration for e-waste treatment and recovery of metals, using conventional or municipal solid waste (MSW) incinerators could be dangerous. For instance, Cu acts as a catalyst for dioxin formation when flame retardants are in combination with MSW [119]. This was one of the prime reasons for Hg (36 tonnes/year) and Cd (16 tonnes/year) release in the open environment in the EU region in the early 20s [119]. Furthermore, incineration being conducted in the presence of oxygen, readily oxidizable metals may get oxidized, potentially reducing the efficiency of metal recovery. This limitation has motivated researchers to explore alternative methods.

6.2.2. Pyrolysis

The thermochemical breakdown of organic matter at high temperatures in the absence of air or oxygen is known as pyrolysis. It entails modifications to the physical and chemical structures. A fraction of organic material present in the waste stream is broken down into molecular compounds (such as bio-oil or fuel-gas) during the pyrolysis process that can be used, for example, as fuel. When organic materials undergo pyrolysis, a solid residue rich in carbon (along with other inorganics and metals) is left behind, along with gas and liquid products. The substance being pyrolyzed and the parameters of the process determine the proportions of solid, liquid, and gas yields [120]. Various studies have been conducted targeting precious metal recovery from e-waste using pyrolysis. Investigations into the vacuum pyrolysis of used PCBs at 240 °C were conducted by Zhou and Qiu [121]. About 69.5% of the experiment’s yield was solid, 27.8% was liquid, and 4.4% was gas. Glass fiber, electronic parts, metals, and other inorganic materials that may be recycled for additional processing made up the solid residue. The process produced a gaseous product that was abundant in CO, CO₂, CH₄, H₂, and other elements. Moreover, Jadhao et al. [122] adopted an integrated approach for metal recovery from e-waste through pyrolysis at 500 °C for 30 min, followed by ultrasonication for 30 min and reported 90% wt% efficiency for metal fraction recovery along with 18% gas yield (calorific value: 30 MJ/m³) and 5% of oil yield with energy potential of 34 MJ/kg. This integrated approach opened the scope for the simultaneous production of high calorific value oil and gas along with precious metals. Research work by Mir and Dhawan [123] demonstrated the efficacy of pyrolysis (300–700 °C) followed by leaching for metal recovery from integrated circuits installed in PCBs, which summarizes heavy metal recovery efficiencies of 96.9% (Cu), 89% (Fe), 64.6% (Ni), 57.1% (Pb), and 33% (Ag). Huang et al. [124] investigated the effects of microwave and conventional pyrolysis as pretreatments of waste PCBs prior to the acid-leaching process for recovery analysis of copper and gold and reported 96% and 75%, respectively. Microwave pyrolysis resulted in higher weight loss of waste PCBs, facilitating better metal recovery. Since pyrolysis occurs in the absence of oxygen and comparatively at lower temperatures (400–600 °C), metals usually do not change their states over the process, unlike incineration, thereby making this process more efficient for metal recovery.

6.2.3. Gasification

Unlike pyrolysis, which occurs without any oxidant, gasification is characterized as a process that requires an additional agent known as a gasifying agent. It is the partial oxidation of the waste stream to produce syngas and a solid residue usually known as char [120]. Sometimes, the feedstock is pretreated before gasification to enhance the process efficiency [105]. According to published research, gasification and pyrolysis are not established techniques for recovering metals from electronic waste. On the other hand, it was determined that gasification was a legitimate technique for handling municipal solid waste. The gasification of PCBs in molten carbonates using steam was recently tested in a laboratory, where pyrolysis followed by steam conversion of polymers from PCBs resulted in hydrogen production [125]. In a recent pilot-scale study targeting the mechanical recycling of e-waste, precious metals, including copper, gold, and palladium recovered by approximately 26%, 45%, and 14%, respectively, under various combinations of gasification conditions [126]. Gasification and its slag could be effective treatment options for precious metals recovery from e-waste. For example, Nie et al. [127] conducted a recovery study of gold from PCBs using waste coal gasification slag (CGS) as adsorbents and concluded that the increased absorption capacity of CGS was up to 40.3 mg/g. Since gasification is often used for thermal treatment of biomass for syngas production [128]. Co-gasification of e-waste and organic waste could provide two-way advantages in terms of biofuels and rare earth metals (REMs) from e-waste. In this regard, Parveg et al. [129] proposed a recycling pathway for co-gasification of e-waste and biomass, following which they attained the recovery of Neodymium (Nd), Dysprosium (Dy), Praseodymium (Pr), Terbium (Tb), Gadolinium (Gd) and Samarium (Sm) as REMs from hard drives, computers, and e-vehicles. Moreover, gasification decoupling with another thermochemical treatment method could be efficient for metal recovery and energy saving. In this regard, Khaobang et al. [130] conducted e-waste pyrolysis and decoupling biomass gasification and reported metal recovery of 83.8% and 89.8% from PCB char and PCB ash, respectively. Conclusively, the co-gasification strategy of biomass and e-waste could be an energy-efficient alternative for syngas production and precious metal recovery.

6.2.4. Advanced Thermal Plasma Technology

Currently, the utilization of thermal plasma in diverse studies has expanded to extract metals from waste due to its intrinsic benefits, including elevated temperatures that facilitate the separation of slag metal and the presence of reactive species that enhance reaction kinetics and decrease reaction duration. For example, a few researchers utilized a direct current (DC) extended arc plasma torch system with a capacity of 35 kW to process e-waste (in crushed form) through pyrolysis. The reactor was operated at temperatures ranging from 1675 to 1875 K utilizing argon. In this treatment process, the e-waste was subjected to melting, after which the metals (Cu, Al, and Fe) in a mixed state were leached using HCl in conjunction with H₂O₂ as a depolarizer [120]. A study by Samal and Blanco [131] demonstrated the application of thermal plasma arc systems in treating various wastes, including e-waste, for metal recovery from PCBs. The plasma processing of waste PCB led to ~76% of metal recovery for precious metals, including Ag, Au, Cu, Pb, Pd, and Sn, along with the release of a significant amount of carbon monoxide. Moreover, Szałatkiewicz [132] utilized a plasmatron plasma reactor equipped with three 20 kW arc plasmatrons for processing 36 kg of waste PCBs at an operating temperature of 1750 °C and attained average recovery rates of 76% for precious metals (Ag, Au, Pd, Cu, Sn, and Pb) reporting only shortcoming of excessive energy requirement (2 kWh per kg of waste) for processing.

Advanced metal extraction technologies offer innovative solutions for sustainable resource recovery, each with distinct advantages and challenges. While these technologies show promise, further research is needed to optimize their feasibility and industrial applicability as discussed in

Table 5. Comparison of advanced metal extraction technologies: Processes, benefits, and challenges.

Technology	Process	Advantages	Limitations	References
Bioleaching	uses microorganisms to extract metals	Environmentally friendly, low energy consumption	Slow process; requires controlled conditions	[133]
Supercritical Fluid Extraction	Uses supercritical CO2 to dissolve and extract metals	No toxic chemicals, high-efficiency	High equipment cost, complex operation	[134]
Plasma Arc Recycling	Uses high-temperature plasma to break down E-waste	High metal recovery rate, minimal emissions	Energy-intensive, expensive setup	[135]
Ionic Liquid Extraction	Uses ionic liquids to selectively dissolve metals	High selectivity, reusable solvents	High cost, limited scalability	[136]
Electrodialysis	Uses electric potential to separate metals	Efficient metal separation, low waste generation	High energy consumption, requiring pure solutions	[137]

.

7. Regulations Vis-à-Vis E-Waste Movement, Management, Handling, and Disposal

7.1. Transboundary Movement of E-Waste and SDGs

International trends have demonstrated that e-waste is one of the fastest-growing waste streams across the globe. The e-waste production is observed in accordance with the socio-economic status of a country or region and demands engineered disposal considering their serious health and environmental concerns [138]. Despite an enormous generation of e-waste and its impact due to open disposal in various countries, its recycling is often not carried out at its origins. Nevertheless, the movement of e-waste has gathered significant attention over the years, which involved the transboundary movement of e-waste from developed countries (EU, USA, Australia, Japan, Korea, etc.) to developing countries (India, China, etc.), where economic e-waste treatment and disposal are prevailing [38,139]. Transboundary movement of e-waste is mainly due to the economic treatment, ease of regulations, and poor enforcement of e-waste management rules in developing countries [140].

It should be emphasized that comparatively stringent laws (Restriction of Hazardous Substances (RoHS) 1 and 2-directives) prevail in China to restrict the reuse of certain hazardous matters in electrical/electronic equipment, thereby reinforcing to look for alternative transboundary treatment in the West African countries due to leniency in e-waste handling rules [33,78,84]. Moreover, in view of the e-waste movement for its affordable treatment and to avoid its illegal shipment, the European Commission prescribed recommendations as a part of the Countering WEEE Illegal Trade (CWIT) project (2013–2015) [141]. Under the aforementioned project, ref. [141] observed that 1.5 million tonnes of e-waste were anticipated to be exported from Europe, containing approximately 26.67% of total e-waste as undocumented exports and 1/3^rd as used electronic equipment. Such eye-opening findings strongly call for a more accountable e-waste management framework at the regional and global levels.

Another promising reason for opting transboundary movement of e-waste by developed countries is that the cost of recycled metals and extraction costs from e-waste in origin countries are tremendously huge, which often comes out to be much less than the potential value produced from metals [6]. Also, developed countries have already enforced stringent environmental regulations and extraction taxes in the recycling process, making e-waste treatment and handling uneconomical [142]. On the other hand, developing countries possess cheaper labor costs, diluted taxes, and poorly regulated yet economically favorable [143]. However, considering severe environmental impacts and socio-economic factors, the inter-country movement of e-waste could be promoted under the strict supervision of e-waste handling, management, treatment, and disposal laws.

Sustainable Development Goals (SDGs) are linked with e-waste management and eco-friendly disposal, hence [144] recommends that inter-country movement of e-waste can be adopted to achieve complementary SDGs in needful countries including Goal 3 (good health and well-being), Goal 11 (sustainable cities and communities) and Goal 12 (responsible consumption and production). Since the SDGs aim to integrate environmental, economic, and social horizons for overall development, e-waste management is vital for environmental protection and generating resources. Among the aforementioned SDGs, specific goals 3.9, 11.6, 12.4, and 12.5 are linked to e-waste management issues. These specific goals relate to interlinked impacts between human health and the environment, with the handling of hazardous substances containing complicated life cycles [145]. The reuse and recycling of e-waste is recommended to bridge the digital gap to maintain accessibility for information and communication technologies (ICT) between underprivileged and rich countries and communities [142].

It should be stressed that the cardinal challenge is to reduce waste material, as ~3/4^th of total e-waste is discarded for disposal in landfills or open dumps in developing countries, which in turn contribute to environmental and human health issues [78]. Bifurcation of e-waste and reusable electrical and electronic equipment is vital here to reduce such waste, that again creates newer challenges due to different legal interpretations and ban regulations [80]. For example, shipped e-waste pertains to electronic parts with little functioning life, but are discarded in the receiving country due to legal or socio-economic reasons, leading to disposal without complete recovery. Hence, considering Agenda 2030, if transboundary movement of e-waste is practiced, achieving SDGs would require establishing relevant e-waste management laws and regulations, promoting education, and their effective enforcement.

In view of the transboundary movement of e-waste, multiple regulations at the international level have been developed and implemented for its monitoring and control. The Basel Convention, adopted in 1989 and enforced in 1992, is a treaty on hazardous waste containing e-waste. Its prime aim is to safeguard the environment and human health from the generation, mishandling, movement, and disposal of hazardous and toxic wastes [146]. It is framed to control e-waste movement, preferably to prevent its uncontrolled transfer, excluding radioactive substances from developed countries to developing countries with regulations to permit the reuse and recycling of shipped waste [146]. Presently, 178 members of the Basel Convention’s Conference of Parties (COP) recommended several verticals to reinforce environmentally sound management (ESM). In 2002, the ‘Mobile Phone Partnership Initiative’(MPPI) was launched to improve consumer attitudes, opting best reuse, refurbishing, recovery, recycling, and disposal solutions with the cooperation of political governance. Furthermore, in 2008 and 2011, the Partnership for Action on Computing Equipment (PACE) and technical guidelines on the transboundary movement of e-waste were affirmed, respectively. The parties of the Basel Convention also adopted the Nairobi Declaration for ESM of e-waste in 2006, followed by the Cartagena Declaration 2011 for preventing, minimizing, recovering, and eco-friendly management of hazardous waste, including e-waste [144].

7.2. International Initiatives/Regulations on E-Waste Management

Apart from the Basel Convention, there are several initiatives undertaken at the country, regional, and international levels for the sustainable and environment-friendly disposal of e-waste. The European Union (EU) framed the E-waste directives (Directive 2002/96/EC, February 2003), which recommend preferring the reuse of e-waste, if possible, rather than its recycling. As per Section 4 of these directives, generators are responsible for collecting and treating their end-of-life electronic and electrical equipment [147]. After implementing these e-waste directives, the EU retained nearly 67% of e-waste as unaccounted for and plausibly exported illegally to developing countries, processed by inferior treatment options, or sent to landfills for disposal [148]. For rectification of such issues, the EU amended the directives as the WEEE Directive (2012/19/EU, February 2014) aimed to handle elevated volumes of e-waste produced [149]. As a part of initially proposed directives, i.e., “RoHS Directive (2002/95/EC) [150]”, the use of hazardous materials in e-waste is prohibited and even restricted for recycling, which later on recommended to go for safer alternatives to hazardous substances present in e-waste such as heavy metals (Pb, Hg, Cd, Cr, etc.), flame retardants, polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) [149].

The G-8 countries are mandated to establish ‘3Rs’ involving reduce, reuse, and recycle initiatives (Japan, 2005) in existing waste management systems. It is oriented to build a sound-material-cycle society by implementing the 3Rs and changing manufacturing and utilization behaviors. The 3Rs initiative was further ratified at the regional level by a collaboration of the United Nations Centre for Regional Development (UNCRD), and the Ministry of the Environment, Government of Japan, which suggests the inclusion of 3Rs in the e-waste management sector [151].

The StEP initiative run by the Institute for the Advanced Study of Sustainability (Germany) was launched in March 2007 by involving 51 party members worldwide including international organizations, policymakers, NGOs, academic institutions, and business organizations. This initiative recommended promoting research and preparing an action plan for sustainable e-waste management [152].

There are regulations to ensure that e-waste is processed by producers through the procurement of reusable and recyclable materials and further disposed of safely without imposing any environmental concerns [153]. The EPR is considered an indirect European Commission legislation framework to ensure that market competition is connected to attain an aimed environmentally sound management of e-waste [149,154]. These regulations express the importance of e-waste-producing companies to practice their legal duty to retrieve end-of-life products for safer disposal [140]. Regulations of the EPR reflected sincere transformation in environmental regulations and their amendments, worldwide [155]. Such changes are prioritized mainly in the promotion of lifecycle thinking and remedial measures for end-of-life product handling through goal-oriented approaches, which ultimately benefit producers to simultaneously improve their products, processes, and the functioning of after-life treatment units. The policy verticals included under the EPR domain encompass various fees (product, taxes, advance recycling fees, virgin material taxes, and their possible combinations) to enforce the “pay-as-you-throw” concept for the handling of discarded waste to ensure its adequate treatment and safe disposal [154,155]. There are several country-based e-waste legislations comprehensively being practiced in managing e-waste in an environment-friendly manner.

7.3. Perspectives on E-Waste Management Legislations Around the Globe

7.3.1. The United States of America (USA)

In the USA, some instances were reported with leniency in the disposal of discarded e-waste in landfills, without practicing environmental legislation strictly [155]. However, distinct federal states further went on revising regional laws to regulate discarded e-waste to protect the environment [156]. Initially, the Resource Conservation and Recovery Act (RCRA) was enacted in the USA in 1976, which was framed to direct solid hazardous waste disposal in favor of environmental and human health with energy and natural resources conservation aims [157]. Under this act, hazardous e-waste is obligated to be handled properly in accordance with the specific disposal regulations via its identification as per the USEPA criteria as ‘hazardous waste’. Further, in the year 2011, the federal government reinforced the “National Strategy for Electronics Stewardship (NSES)” as fundamental for rectifying the design of electronic items to improve their usability and maintain the lifecycle of electronic equipment environment-friendly [156]. One of the strategies prescribed by NSES is to enhance the collaboration with federal agencies, state governments, and other stakeholders, including industry and the public, to promote safe and sustainable disposal of e-waste. Thus, it covers a wide range of objectives, including greener design of electronic equipment, involvement of federal agencies, and ultimately protecting the environment from adverse effects of e-waste disposal, and to practice safe exports of e-waste to developing countries [155]. The federal government has also launched several initiatives for public awareness, which provide guidance for consumers and businesses. For example, the eCycling initiatives recommend opting for e-waste recycling from certified recyclers approved by the USEPA and describe the donation of e-waste. Moreover, the agency also conducts public awareness campaigns and social events that instigate the involvement of society to take remedial actions for the eco-friendly disposal of e-waste.

7.3.2. Germany

One of the biggest producers of e-waste in Europe is Germany, which produced over 1.6 million metric tons of e-waste in 2022, or one-tenth of all e-waste produced in Europe [158]. In addition to ratifying the Basel Convention, Germany amended the Act Governing the sale, return, and environmentally sound disposal of electrical and electronic equipment (Electrical and Electronic Equipment (EEE) Act-ElektroG), Ordinance on waste electric and electronic materials (ElektroStoffV) and the Cost Ordinance on the Electrical and Electronic Equipment (EEE) Act (ElektroGKostV) to incorporate the European Directive (2012/19/EU) [149] into German law [151]. The Electrical and Electronic Equipment Act-ElektroG mandates EEE manufacturers to enroll their electronic equipment and obtain a WEEE number prior to product launch, to ensure a product design that is easy to disassemble and periodic reporting to the German supervisory authority for waste electronics and electrical equipment [159].

In Germany, the Federal Environmental Agency (UBA) is a supervisory authority which reports annual figures in coalition with clearing houses based on reported quantities in each WEEE category and on how much quantity is to be reused, recycled, recovered, or exported. The transboundary movement of e-waste, categorized as hazardous waste, is only permitted in countries in the Organization for Economic Co-operation and Development (OECD) cooperation [7]. However, if E-waste is characterized as non-hazardous based on the Basel convention, it can be allowed to be exported to other countries, but only when it is compliant with the RoHS Directives and contains a CE mark [160].

7.3.3. China

China, being one of the rapidly growing countries and the largest exporter of ICT products worldwide, even crossing Japan, the EU, and the USA, has contributed to e-waste production considerably [36]. In 2023, China generated more than 1.5 million tons of e-waste, mainly from electrical and electronic manufacturing plants, production of household electric appliances, ICT production units, and imports from other countries for treatment and disposal [161]. At present, China is a vital global player in e-waste recycling by giving employment to more than 2.6 million people (in 2019), mostly creating job opportunities in informal sectors [161].

To address e-waste pollution and safe disposal, the Chinese government has taken multiple remedial actions for abstaining from the illegal import of e-waste and other hazardous waste since the year 2000, via enforcement of the Technical Policy on Pollution Prevention and Control of Waste Electrical and Electronic Products (2006) and the Administrative Measures for the Prevention and Control of Environmental Pollution by Electronic Waste (2007) since 2006 [11]. Moreover, a separate licensing scheme was also launched for the engineered disposal of e-waste after significant recycling in only authorized stations [13]. Similar to the EU’s RoHS directives, the Chinese Ministry of Industry and Information Technology (MIIT) launched in 2006 a new China RoHS-1, which administers the potential pollution caused by WEEE end products. Further, it was ratified as China RoHS-2 in 2016, aimed to reduce the use of hazardous heavy metals (Pb, Cd, Hg, and Cr), and Per- and Polyfluoroalkyl Substances (PFAS) containing flame retardants, even in equipment manufactured for export [145,162]. As per these rules, the same six substances mentioned in the EU’s RoHS directives are permitted to be used in controlled limits [162].

The Chinese legislations mandate the responsibility and roles of producers for e-waste management by imposing fees for the treatment. Manufacturers of household electronic/electrical products are lawfully forced to adopt a “green” design, which is recycle-friendly and easy to reuse [7]. Collection and recycling responsibility is given to manufacturers, retailers, and waste collection entities with appropriate licensing in compliance with government-prescribed standards. The Chinese government’s municipal environmental protection departments are liable for approval of licensed treatment facilities for e-waste recycling practices based on their infrastructure, monitoring systems, compliance, and environmental management efficacy [74]. China aims to achieve an e-waste recycling efficiency of 50% by 2025, as part of its broader circular economy and sustainability initiatives, but 60–80% involvement of the unorganized informal sector, often involving illegal and unsafe recycling practices, is likely to affect recycling efficiency [162]. In regions of Guiyu and Guangdong Province, the informal processing of e-waste has been a significant economic activity, involving numerous workers and small-scale un-engineered operations [163]. Despite advanced regulatory frameworks, the involvement of the informal sector, lack of awareness, and personal interests of informal recyclers are consistently reinforcing to misalign the goals for the successful implementation of regulations.

7.3.4. India

India, the country with the highest population, has been expanding e-waste quantities over the decades and currently stands among the top four nations in producing e-waste [164]. India imports scrap electronic discarded products, including processing units, projectors, computer components, wires, discarded mobile phones, etc., from Western countries [10]. Most of the imported e-waste and discarded electronic devices from India itself are disposed of illegally due to a lack of strict supervision, which obligates the imposition of stringent e-waste management rules [12]. At first, until 2010, e-waste management was lawfully included under the Hazardous Waste (Management and Handling) Rules; later, a separate legislation, the E-waste (Management and Handling) Rules 2011, was launched under the umbrella of the Environmental Protection Act (EPA) 1986 [77]. These regulations encompass manufacturing, commercial, and EE equipment processing units and mandate environmentally sound treatment and disposal of e-waste. These rules involved EPR and were dedicated to vigilance regarding the hazardous elements of the e-waste [165].

It is worth stressing that as an amendment, new rules were introduced as the E-waste (Management) Rules 2016, which extended the duty of producers, collection units, recyclers, and dissemblers, making them responsible for taking care of e-waste collection and environmentally sound channelization up to disposal [12]. Furthermore, in 2018, these rules were amended and introduced as the E-waste (Management) Amendment Rules 2018 to accelerate the process of implementing eco-friendly e-waste management. Although proposed regulations mandate channelized processing of e-waste, successful implementation of the EPR and efficient recycling with appropriate treatment options. Yet, in practice, the current scenario persists astonishingly because of various constraints, including lack of infrastructure, policy enforcement gaps, dominance of the informal sector, lack of public awareness and participation, institutional coordination issues, and techno-economic constraints [166]. According to a recent report, India has only 472 authorized dismantlers and recyclers, which is insufficient to handle the country’s e-waste volume, reinforcing unlawful and excessive involvement of informal sectors [167]. The predominance of the informal sector in E-waste processing, which is 95% in India, limits the enforcement of regulations [26]. Megacities of India, such as Delhi, Mumbai, Kolkata, Chennai, Ahmedabad, etc., have more than 3000 informal e-waste recycling units operating without formal regulatory approval, leading to higher environmental and health hazards [26]. Excessive informal recycling of e-waste also raises the concern of misjudgment of India’s e-waste recycling market, thereby inhibiting successful policy implementation. For example, the formal e-waste recycling market in India was valued at USD 1.60 billion in 2024, with projections to reach USD 2.80 billion by 2033, showcasing growth opportunities if informal and formal sectors are integrated [168]. Integrating the informal sector with the formal e-waste management sector can enhance resource recovery, ensure environmental safety, and provide better working conditions for workers [169]. Thus, for the successful implementation of e-waste management regulations, the socio-economic aspects are mandatory to resolve as the foremost action.

The highest authority for ensuring that e-waste is channeled in an environmentally responsible manner is the Ministry of Environment, Forests, and Climate Change (MOEF&CC), Government of India. For the macro-management of e-waste in their respective regions, other government players include the Director General of Foreign Trade (DGFT), the Port and Custom Directorate, the Urban Local Bodies (ULBs), the Central Pollution Control Board (CPCB), and State Pollution Control Boards (SPCBs). In addition, other stakeholders include private organizations such as NGOs and Public–Private Partnerships (PPPs) as well as academic and research institutions such as the Indian Institute of Technologies (IITs), Indian Institute of Information Technologies (IIITs), National Institute of Technologies (NITs), and National Institute of Electronics & Information Technology (NIELIT) for technology transfer and training to relevant operators. Figure 9 shows several important parties engaged in the management of e-waste in India. In India, the informal sector plays a vital role in e-waste management, including ~90% of e-waste recycling by such units [10].

7.4. Barriers and Solutions Towards Effective Policy Implementation

Despite state-of-the-art initiatives such as the E-Waste Management Rules 2016, EPR, and China RoHS-2 in developing countries like India and China, managing E-waste effectively has been a major challenge over time. In India, informal recycling of e-waste dominates and handles approximately 90% of e-waste, involving around 1% of the country’s population in informal waste management and recycling [170]. In informal recycling with local waste dealers (kabadiwalas), producers prefer to fulfill the personal agenda of making localized post-sale profits, thereby restraining the waste flow to decentralized facilities [171]. Apart from localized recycling by the informal sector, other major barriers that prohibit successful policy implementation in developing countries are as follows: lack of public awareness, limited access, and lack of engineered infrastructure, security, and data concerns [170]. In developing countries, such barriers require tailored solutions based on country-specific regulations, as depicted in Table 6. In addition, a comparison of e-waste legislation prescribed by various developed and developing countries is listed in Table 7.

Economic and cultural differences greatly influence the effectiveness of e-waste management practices and relevant policy interventions. In developed countries, despite the uplifted economic status, higher per capita income, augmented consumerism, and strict policy supervision, e-waste policy enforcement and formal recycling have not been appreciably higher, in most cases. For example, the United States has—high consumer-driven culture, and regionalized regulations hamper cohesive e-waste management. As per a recent case study, despite of high per capita e-waste generation of ~32.1 kg, the recycling rate has been below 16% [172]. In the USA, the e-waste recycling rate fluctuates significantly according to economic class. Higher-income groups generally recycle e-waste, often due to access to recycling units, policy awareness, and risk involvement. Lower- or middle-income households also prefer to resell or donate used electronic devices with mutual preferences or recycling informally due to a lack of awareness, transportation, and knowledge for safe disposal. Such discrepancies advocate the need for an impartial approach to e-waste recycling infrastructure and well-directed awareness programs.

In Germany, a comparatively more structured approach is visible, which is indeed influenced by cultural and economic variables, yet strong environmental consciousness is embedded in household individuals and robust federal policy allied with the EU’s WEEE Directives. The e-waste recycling rates are ~37% because of federal investments in the circular economy and recycling infrastructure development [173]. Government policy awareness regarding recycling and environmental risk is embedded in school-level education and formally organized public campaigns [174]. A recent case study incorporating 30 European countries revealed that per capita GDP is a vital factor which influences the e-waste recycling rate and highlighted that increased household income class in Germany utilizes formal e-waste processing facilities [175]. Among all the EU countries, Switzerland established a global standard in cultural and economic synergy for e-waste recycling and policy enforcement. Switzerland has one of the highest e-waste recycling rates (~63%) with a 23.3 kg per capita per day e-waste generation rate [176]. The augmented socio-economic model, cultural responsibility, and acceptance of formal recycling as a civic duty foster a high-trust and high-compliance culture [175]. Moreover, the ARF charged in retail price is publicly accepted, which indicates economic prediction, while a deeply rooted environmental ethic ensures pronounced public obedience [177]. Similarly, in Sweden, active public participation in e-waste recycling is observed to utilize advanced sorting and processing technologies, leading to high e-waste recycling rates ranging between 74.1 and 86.6% in 2019–20, which sufficiently surpasses the EU’s average recycling rate of 42% [178]. Strong law enforcement, including EPR, end-of-life waste management compliance, and public awareness, are vital factors for such benchmarks. In France, the e-waste recycling rate stood around 32–42% as of the year 2022, aligning with the EU’s average, possibly attributed to high cultural and socio-economic variability [175]. Despite the implementation of the EPR policy, only 1/3^rd of e-waste is formally collected and recycled, while the remaining is stored, improperly discarded, or processed through informal paths. Increasing awareness and intrinsic motivations towards e-waste recycling, environmental impacts could be more significant drivers rather than external incentives.

The socio-economic and cultural disparities are often more profound in developing nations than in developed countries, owing to higher differences in income classes, education, infrastructure, and ethnic diversity. In developing countries, the prevalent practice is storing old e-waste at the household level and negligently delaying the recycling process. For example, in India, e-waste recycling is mostly (90%) handled by informal waste workers or scrap dealers (kabadiwalas) operating illegally and overlooking formal regulations. Moreover, scrap dealers predominantly belong to marginalized communities, including those deprived of income and facing social inequalities, apart from some exceptions in metro cities (Delhi, Mumbai, Jaipur, etc.) where e-waste dealers belong to the Malik community—a trader caste [170]. Moreover, as per a recent study, the lower income groups in Bihar state—earning less than ₹6000 pm. accounting for 34.14% of households, have no access to safe and formal exposure to e-waste recycling services; hence, they opt for localized recycling as an employment opportunity [179]. Women contribute a substantial fraction of the total informal e-waste labor force, but they are often demoted to lesser-salaried, labor-intensive roles, including e-waste collection and manual sorting. They struggle with restricted opportunities for improvement and are underrepresented in decision-making positions for e-waste recycling. In deprived areas of metro cities—for example, in Seelampur, Delhi, around 50,000 individuals are informally employed in e-waste processing units without safety measures, leading to health risks [180].

China—a leading global e-waste producer, also suffers extensively because of 60–80% of informal and underregulated recycling [181]. The informal e-waste recycling sector in China is mostly run by small-scale units, and family-level household workshops practicing rudimentary processing methods such as manual disassembling, open burning, and acid leaching, creating severe local health problems [182]. In small towns, informal e-waste processing and reselling is even practiced as the sole source of income for a family—often unknowingly practiced due to a lack of awareness about policy [183]. However, in urban areas, economic class and social stratification play major roles in affecting rule-wise e-waste processing. In urban centers like Shanghai and Beijing, socio-economic disparity affects behaviors towards e-waste processing. In Shanghai, around 44.2% of households earn less than ¥100,000 annually as compared to 25.8% in Beijing—which limits formal recycling through less exposure to specialized facilities [184]. In the same way, the Guiyu in Guangdong province receives more than 150,000 individuals as migrant workers engaged in illegal e-waste processing—making the city an ‘epicenter’ of informal e-waste recycling, because of lesser individual liability towards city environmental health and opportunity to earn more profit [182].

Table 6. Important barriers in e-waste policy implementation, described with case-specific examples (non-exhaustive and might be valid for other cases too) and policy-based solutions.

S. No.	Barrier to E-Waste Policy Implementation	Description	Country-Specific Example	Policy-Based Solution
1	Low public awareness	Population in developing countries lacks knowledge about environmental and human health imposed by e-waste mishandling because of limited technical outreach.	India: 70% of urban customers using electronics are unaware of collection and processing units [185].	Initiatives such as educational schemes under India’s E-waste (management) rules 2016 mandate awareness training for producers.
2	Limited access and convenience	Developing countries lack formal collection facilities that discourage rule-based recycling.	Kenya: Less than 5% of counties in different states possess formal e-waste collection centers [186].	Kenya’s National E-Waste Management Strategy recommends zonal e-waste collection and processing centers and county-level infrastructure.
3	Concerns for data security and misunderstandings	People in developing countries show concerns over data theft from discarded electronic items.	South Africa: A case study demonstrates that approximately 40% of people show reluctance to data misuse while handing over electronics to formal middlemen. [187].	South Africa’s e-waste policy (National Environmental Management Waste Act 2008) recommends authorized recycling units and engineered processing services.
4	Weak public involvement	Insignificant outreach results in less participation in e-waste management policy acceptance.	Nigeria: Inferior people turnout despite significant campaigns [188].	Nigeria’s National Environmental (Electrical/Electronic Sector) Regulation and NESREA guidelines recommend county authorities for enhanced involvement of community people.
6	Lack of stakeholder coordination and partnerships	Lack of cooperation and coordination between government authorities and non-profit organizations reduces the impact of policy implications.	Ghana: Only 13% of stakeholders are aware of e-waste rules, and overlapping of stakeholders’ roles inhibits regulation implementation [189].	Country-wise supervision of implementation of Ghana’s Hazardous and Electronic Waste Control and Management Act (Act 917) that integrates roles for EPAs and local authorities.
7	Limited use of digital media	Uninterest in social media promotion for e-waste policy sharing and awareness despite extensive use of platforms.	Bangladesh: Almost 70.79% of the country’s population is active on social media but only 29% of them are aware of e-waste management rules [190].	Digital Bangladesh Vision initiative may help in encouraging ICT platforms towards engineered recycling awareness via integration into apps and social media campaigns.
8	Limited financial incentives	Despite knowing recycling income, people hesitate to send WEEE items due to a lack of incentives or appropriate prices as a recycling motivation.	Brazil: Informal collectors provide very low recycling prices (R$0.40 to R$4.00 per kg), making e-waste unattractive for households. Only about ~3.6% of the population’s e-waste is formally recycled [191]	Brazil’s National Solid Waste Policy may include tax incentives or subsidies for e-waste recycling. The EPR amendment may increase subsidies for formal recyclers and fix a compulsory buy-back plan for WEEE-producing households.
9	Lack of community-driven initiatives	Lack of people’s participation weakens accountability and increases ignorance about e-waste policies.	Vietnam: Lack of pilot programs reinforced 81–100% of people in Ho Chi Minh city to go for informal recycling thereby undermining formal recycling policy efforts [192].	Vietnam’s National Strategy on Integrated Waste Management and EPR policy should emphasize community-level awareness and grassroots-level engagements regarding WEEE formal recycling.
10	Disoriented WEEE recycling campaigns and policy promotion	Lack of policy promotion campaigns and inconsistent efforts by authorities impact successful policy implementation.	Pakistan: Despite 98% recycling potential, misalignment of policy and inefficient promotional campaigns affected recycling efforts [193].	E-waste policy campaigns following a bottom-to-top approach would raise public awareness about Pakistan’s Draft E-waste Management Rules, which recommend long-term public cooperation and centralized follow-up of social campaigns.
11	Informal sector dominance	Dependency on informal recyclers following illegal pathways and offering irregular recycling prices ultimately limits successful policy implementation.	China (Guiyu): Informal e-waste recyclers process ~70% of e-waste, undermining formal policy implementation and causing major health risks [194].	China’s 2016 e-waste policy may recommend financial incentives, training programs, and certification campaigns for integrating the informal sector.

Table 6. Important barriers in e-waste policy implementation, described with case-specific examples (non-exhaustive and might be valid for other cases too) and policy-based solutions.

S. No.	Barrier to E-Waste Policy Implementation	Description	Country-Specific Example	Policy-Based Solution
1	Low public awareness	Population in developing countries lacks knowledge about environmental and human health imposed by e-waste mishandling because of limited technical outreach.	India: 70% of urban customers using electronics are unaware of collection and processing units [185].	Initiatives such as educational schemes under India’s E-waste (management) rules 2016 mandate awareness training for producers.
2	Limited access and convenience	Developing countries lack formal collection facilities that discourage rule-based recycling.	Kenya: Less than 5% of counties in different states possess formal e-waste collection centers [186].	Kenya’s National E-Waste Management Strategy recommends zonal e-waste collection and processing centers and county-level infrastructure.
3	Concerns for data security and misunderstandings	People in developing countries show concerns over data theft from discarded electronic items.	South Africa: A case study demonstrates that approximately 40% of people show reluctance to data misuse while handing over electronics to formal middlemen. [187].	South Africa’s e-waste policy (National Environmental Management Waste Act 2008) recommends authorized recycling units and engineered processing services.
4	Weak public involvement	Insignificant outreach results in less participation in e-waste management policy acceptance.	Nigeria: Inferior people turnout despite significant campaigns [188].	Nigeria’s National Environmental (Electrical/Electronic Sector) Regulation and NESREA guidelines recommend county authorities for enhanced involvement of community people.
6	Lack of stakeholder coordination and partnerships	Lack of cooperation and coordination between government authorities and non-profit organizations reduces the impact of policy implications.	Ghana: Only 13% of stakeholders are aware of e-waste rules, and overlapping of stakeholders’ roles inhibits regulation implementation [189].	Country-wise supervision of implementation of Ghana’s Hazardous and Electronic Waste Control and Management Act (Act 917) that integrates roles for EPAs and local authorities.
7	Limited use of digital media	Uninterest in social media promotion for e-waste policy sharing and awareness despite extensive use of platforms.	Bangladesh: Almost 70.79% of the country’s population is active on social media but only 29% of them are aware of e-waste management rules [190].	Digital Bangladesh Vision initiative may help in encouraging ICT platforms towards engineered recycling awareness via integration into apps and social media campaigns.
8	Limited financial incentives	Despite knowing recycling income, people hesitate to send WEEE items due to a lack of incentives or appropriate prices as a recycling motivation.	Brazil: Informal collectors provide very low recycling prices (R$0.40 to R$4.00 per kg), making e-waste unattractive for households. Only about ~3.6% of the population’s e-waste is formally recycled [191]	Brazil’s National Solid Waste Policy may include tax incentives or subsidies for e-waste recycling. The EPR amendment may increase subsidies for formal recyclers and fix a compulsory buy-back plan for WEEE-producing households.
9	Lack of community-driven initiatives	Lack of people’s participation weakens accountability and increases ignorance about e-waste policies.	Vietnam: Lack of pilot programs reinforced 81–100% of people in Ho Chi Minh city to go for informal recycling thereby undermining formal recycling policy efforts [192].	Vietnam’s National Strategy on Integrated Waste Management and EPR policy should emphasize community-level awareness and grassroots-level engagements regarding WEEE formal recycling.
10	Disoriented WEEE recycling campaigns and policy promotion	Lack of policy promotion campaigns and inconsistent efforts by authorities impact successful policy implementation.	Pakistan: Despite 98% recycling potential, misalignment of policy and inefficient promotional campaigns affected recycling efforts [193].	E-waste policy campaigns following a bottom-to-top approach would raise public awareness about Pakistan’s Draft E-waste Management Rules, which recommend long-term public cooperation and centralized follow-up of social campaigns.
11	Informal sector dominance	Dependency on informal recyclers following illegal pathways and offering irregular recycling prices ultimately limits successful policy implementation.	China (Guiyu): Informal e-waste recyclers process ~70% of e-waste, undermining formal policy implementation and causing major health risks [194].	China’s 2016 e-waste policy may recommend financial incentives, training programs, and certification campaigns for integrating the informal sector.

Table 7. Country-wise e-waste management and comparative factsheet involving legislation, directives, export-import, and producers’ responsibility and disposal recommendations.

S. No.	Country	Legislation	Producers Responsibility	Collection and Recycling	Export or Transboundary Movement	Audits and Monitoring System	RoHS Directives	References
1.	United Kingdom (UK)	The Waste Electrical and Electronic Equipment (WEEE) Regulations 2013. The Waste Electrical and Electronic Equipment (Amendment) Regulations 2015	Registration of E-waste under producer compliance scheme. Financing collection, recovery, and eco-friendly disposal of E-waste. Regular recording and reporting of E-waste to competent authorities.	DCFs and PCSs frame setups for E-waste collection via different ways—involvement of local authorities, retail collection stations, and direct collection points. The DEFRA monitors and sets annual targets for E-waste collection.	Permitted under the WSR and TFS rules. E-waste (hazardous or non-hazardous) must follow the import notification by the recipient country. Export of E-waste must be performed only by the approved exporter.	DEFRA is a monitoring agency for the collection and sorting of E-waste under different categories. The compliance scheme charges a one-time fee for monitoring and law enforcement.	Imported E-waste for market practice in the UK must hold compliance under RoHS directives. Mandatory requirements are—CE mark, compliance documents, importers’ details, tradename/mark, contact, and address of exchange partners.	[195,196]
2.	France	The European Directive (2011/65/EU), RoHS directives =	Producers must register in Registre DEEE (French WEEE register). Fund the management of E-waste, inclusive of collection, treatment, and eco-friendly disposal. Proper labeling of E-waste.	Producers organize collections with the cooperation of municipalities. Household E-waste is collected by an authorized agency, OCAD3E. Producers are liable to provide details of e-waste for an appropriate recycling option.	The export of E-waste (either hazardous or non-hazardous) is not allowed outside the OECD.	Third-party audits are conducted by authorized agencies under the supervision of the government to monitor recycling and collection operators.	Not advocated for freight of E-waste that is non-compliant with RoHS directives. Imported E-waste items must follow RoHS directives and carry CE marks for resource recovery and appropriate disposal.	[197]
3.	Japan	Classified based on EEE categories: The Home Appliance Recycling (THAR) Law, 2001—Televisions, Freezers, Air conditioners, and Washing machines. Small Home Appliances Recycling (SHAR) Law, 2013—Mobiles, small E&E equipment	Establishing recovery and recycling arrangements for used EEE. Producers are obligated to fund the collection and recycling of used EEE.	Designation of used products as “old or new” is imposed under THAR law (2001), which enables retailers to recollect consumers’ small, or several times sold products. EEE manufacturers can arrange collection by a third party such as AEHA. In rural areas, collection and recycling services are operated by the local government or AEHA, whichever is operable.	NA	The government has the authority to investigate recyclers anytime. Retailers must provide a special receipt to end users to track down the treatment of the collected used product, under the manifest system.	RoHS directives of Japan are combined with Japanese Recycling Law with the JIS C 0950 standard (J-MOSS) [150]. It also mandates restrictions on the same 6 substances (with the same upper limits) as prescribed by EU RoHS but under 7 product categories.	[198,199]
4.	Australia	The National Television and Computer Recycling Scheme and the Product Stewardship (TVs and Computers) Regulations 2011, Australian Government’s Product Stewardship Act 2011.	Fund the E-waste management (collection to disposal). Provide information to consumers for end-use handling, reselling, or disposal. Obtain membership in an approved co-regulatory system.	End-of-life WEEE from domestic entities or small business units can be submitted to designated collection points. Co-regulatory systems are liable for organizing recycling services in spite of producers. They may even appoint third-party contract services or logistics handling companies for collection but under strict supervision.	Allowed as per Basel, OECD, and Waigani Conventions. A prescribed permit (evidentiary certificate by the government) is mandatory if E-waste is in the hazardous category.	Representatives of the Co-regulatory system must submit an annual audit report which is prepared by the auditor appointed by the company or authorized organization for WEEE audits.	NA	[200,201]
5.	Ghana	Hazardous and Electronic Waste Control and Management, Law, (Act 917) (2016) Hazardous, Electronic, and Other Wastes (Classification) Control and Management Regulations (2016)	Ensure environmentally sound management of E-waste either individual or collaborative. Attaining environmental permits, preserving records, and reporting to concerned agencies. Labeling of products with symbols which prevent disposal of discarded waste into garbage. Financing e-waste management.	Only through informal channels. As per the legislation’s recommendation, collection must be by an authorized agency. Dissemblers and recyclers’ duty is to ensure proper treatment of E-waste in the special facility by employing the best treatment option available.	Most non-hazardous e-waste is allowed to be imported with a permit from competent authority. Used CFLs, refrigerators, Acs, and other ODSs are not permitted for import under any circumstances.	Competent authority has set (technical guidelines) the standard to ensure secure disposal of E-waste. Agency may seek stakeholders’ cooperation for maintaining monitoring data and calculation of market share by individual producers.	Restriction on six substances as recommended by the EU’s RoHS, but only change in product categories and scope. Decrease in utilization of hazardous substances in imported E-waste is opinionated by authority within two years after RoHS enforcement.	[150,202]
6.	Switzerland	Ordinance on Movements of Waste (OWM, 2005), Ordinance on the Return, Take-Back, and Disposal of Electrical and Electronic Equipment (ORDEE, 2022)	Must follow theory of Extended Producer Responsibility (EPR). Customers are charged with advanced recycling fee (ARF), inclusive of retail price, which is taken for operating collection, utilization, and disposal of used products. Treatment and recycling facilities are paid according to an index-system which manifests impartial distribution.	Competent authorities (PROs) designate collection points such as public bus or train stations. Paid pick-up may be arranged for commercial units. Swiss PROs authorized 9 recyclers and 83 dissembling units as of 2018 ending.	The OWM is supervising law for the movement of E-waste. Export is subjected to adoption of Basel and the OECD considerations.	The PRO makes sure that assigned recycling companies perform quality checks and maintain standards for recycling. External audits funded by PROs are also employed to ensure transparency in recycling. The FOEN, acts as environmental monitoring & licensing authority	Trade in used electronic and electric products: The restraints on hazardous materials are same as those indicated by RoHS Directives (RoHS2). Banned materials under Swiss Chemical’s legislation are not exported.	[203,204]
7.	Singapore	Resource Sustainability Act 2019; Resource Sustainability (Composition of Offences) Regulations, 2019; Resource Sustainability (Prescribed Regulated Products) Regulations, 2019	Producers are mandated to register with NEA and keep detailed records (weight and number) of all regulated products. Contribution of funds by licensed producers of regulated consumer products under PRS. Regulated non-consumer product producers must ensure collection, monitoring, management, and disposal of their E-waste by proper tracking.	Only licensed collectors and recyclers authorized by NEA can perform treatment and disposal of E-waste. Collection of E-waste is bifurcated under categories of—regulated consumer products or regulated non-consumer products. Former ones are collected by operators under PRS.	NA	Audit of annual report produced by every licensee is conducted. Licensed recyclers are mandated to maintain the recovery/recycling standards. The NEA is responsible for monitoring collected, recycled, and disposed E-waste.	NA	[205,206]

Table 7. Country-wise e-waste management and comparative factsheet involving legislation, directives, export-import, and producers’ responsibility and disposal recommendations.

S. No.	Country	Legislation	Producers Responsibility	Collection and Recycling	Export or Transboundary Movement	Audits and Monitoring System	RoHS Directives	References
1.	United Kingdom (UK)	The Waste Electrical and Electronic Equipment (WEEE) Regulations 2013. The Waste Electrical and Electronic Equipment (Amendment) Regulations 2015	Registration of E-waste under producer compliance scheme. Financing collection, recovery, and eco-friendly disposal of E-waste. Regular recording and reporting of E-waste to competent authorities.	DCFs and PCSs frame setups for E-waste collection via different ways—involvement of local authorities, retail collection stations, and direct collection points. The DEFRA monitors and sets annual targets for E-waste collection.	Permitted under the WSR and TFS rules. E-waste (hazardous or non-hazardous) must follow the import notification by the recipient country. Export of E-waste must be performed only by the approved exporter.	DEFRA is a monitoring agency for the collection and sorting of E-waste under different categories. The compliance scheme charges a one-time fee for monitoring and law enforcement.	Imported E-waste for market practice in the UK must hold compliance under RoHS directives. Mandatory requirements are—CE mark, compliance documents, importers’ details, tradename/mark, contact, and address of exchange partners.	[195,196]
2.	France	The European Directive (2011/65/EU), RoHS directives =	Producers must register in Registre DEEE (French WEEE register). Fund the management of E-waste, inclusive of collection, treatment, and eco-friendly disposal. Proper labeling of E-waste.	Producers organize collections with the cooperation of municipalities. Household E-waste is collected by an authorized agency, OCAD3E. Producers are liable to provide details of e-waste for an appropriate recycling option.	The export of E-waste (either hazardous or non-hazardous) is not allowed outside the OECD.	Third-party audits are conducted by authorized agencies under the supervision of the government to monitor recycling and collection operators.	Not advocated for freight of E-waste that is non-compliant with RoHS directives. Imported E-waste items must follow RoHS directives and carry CE marks for resource recovery and appropriate disposal.	[197]
3.	Japan	Classified based on EEE categories: The Home Appliance Recycling (THAR) Law, 2001—Televisions, Freezers, Air conditioners, and Washing machines. Small Home Appliances Recycling (SHAR) Law, 2013—Mobiles, small E&E equipment	Establishing recovery and recycling arrangements for used EEE. Producers are obligated to fund the collection and recycling of used EEE.	Designation of used products as “old or new” is imposed under THAR law (2001), which enables retailers to recollect consumers’ small, or several times sold products. EEE manufacturers can arrange collection by a third party such as AEHA. In rural areas, collection and recycling services are operated by the local government or AEHA, whichever is operable.	NA	The government has the authority to investigate recyclers anytime. Retailers must provide a special receipt to end users to track down the treatment of the collected used product, under the manifest system.	RoHS directives of Japan are combined with Japanese Recycling Law with the JIS C 0950 standard (J-MOSS) [150]. It also mandates restrictions on the same 6 substances (with the same upper limits) as prescribed by EU RoHS but under 7 product categories.	[198,199]
4.	Australia	The National Television and Computer Recycling Scheme and the Product Stewardship (TVs and Computers) Regulations 2011, Australian Government’s Product Stewardship Act 2011.	Fund the E-waste management (collection to disposal). Provide information to consumers for end-use handling, reselling, or disposal. Obtain membership in an approved co-regulatory system.	End-of-life WEEE from domestic entities or small business units can be submitted to designated collection points. Co-regulatory systems are liable for organizing recycling services in spite of producers. They may even appoint third-party contract services or logistics handling companies for collection but under strict supervision.	Allowed as per Basel, OECD, and Waigani Conventions. A prescribed permit (evidentiary certificate by the government) is mandatory if E-waste is in the hazardous category.	Representatives of the Co-regulatory system must submit an annual audit report which is prepared by the auditor appointed by the company or authorized organization for WEEE audits.	NA	[200,201]
5.	Ghana	Hazardous and Electronic Waste Control and Management, Law, (Act 917) (2016) Hazardous, Electronic, and Other Wastes (Classification) Control and Management Regulations (2016)	Ensure environmentally sound management of E-waste either individual or collaborative. Attaining environmental permits, preserving records, and reporting to concerned agencies. Labeling of products with symbols which prevent disposal of discarded waste into garbage. Financing e-waste management.	Only through informal channels. As per the legislation’s recommendation, collection must be by an authorized agency. Dissemblers and recyclers’ duty is to ensure proper treatment of E-waste in the special facility by employing the best treatment option available.	Most non-hazardous e-waste is allowed to be imported with a permit from competent authority. Used CFLs, refrigerators, Acs, and other ODSs are not permitted for import under any circumstances.	Competent authority has set (technical guidelines) the standard to ensure secure disposal of E-waste. Agency may seek stakeholders’ cooperation for maintaining monitoring data and calculation of market share by individual producers.	Restriction on six substances as recommended by the EU’s RoHS, but only change in product categories and scope. Decrease in utilization of hazardous substances in imported E-waste is opinionated by authority within two years after RoHS enforcement.	[150,202]
6.	Switzerland	Ordinance on Movements of Waste (OWM, 2005), Ordinance on the Return, Take-Back, and Disposal of Electrical and Electronic Equipment (ORDEE, 2022)	Must follow theory of Extended Producer Responsibility (EPR). Customers are charged with advanced recycling fee (ARF), inclusive of retail price, which is taken for operating collection, utilization, and disposal of used products. Treatment and recycling facilities are paid according to an index-system which manifests impartial distribution.	Competent authorities (PROs) designate collection points such as public bus or train stations. Paid pick-up may be arranged for commercial units. Swiss PROs authorized 9 recyclers and 83 dissembling units as of 2018 ending.	The OWM is supervising law for the movement of E-waste. Export is subjected to adoption of Basel and the OECD considerations.	The PRO makes sure that assigned recycling companies perform quality checks and maintain standards for recycling. External audits funded by PROs are also employed to ensure transparency in recycling. The FOEN, acts as environmental monitoring & licensing authority	Trade in used electronic and electric products: The restraints on hazardous materials are same as those indicated by RoHS Directives (RoHS2). Banned materials under Swiss Chemical’s legislation are not exported.	[203,204]
7.	Singapore	Resource Sustainability Act 2019; Resource Sustainability (Composition of Offences) Regulations, 2019; Resource Sustainability (Prescribed Regulated Products) Regulations, 2019	Producers are mandated to register with NEA and keep detailed records (weight and number) of all regulated products. Contribution of funds by licensed producers of regulated consumer products under PRS. Regulated non-consumer product producers must ensure collection, monitoring, management, and disposal of their E-waste by proper tracking.	Only licensed collectors and recyclers authorized by NEA can perform treatment and disposal of E-waste. Collection of E-waste is bifurcated under categories of—regulated consumer products or regulated non-consumer products. Former ones are collected by operators under PRS.	NA	Audit of annual report produced by every licensee is conducted. Licensed recyclers are mandated to maintain the recovery/recycling standards. The NEA is responsible for monitoring collected, recycled, and disposed E-waste.	NA	[205,206]

8. Case Study Overview on Technologies and Regulations

8.1. India

Reportedly in a case study for e-waste processing and recovery of precious metals from PCBs, the bioleaching process was employed using Acidithiobacillus ferrooxidans, and Leptospirillum ferrooxidans to selectively solubilize the Cu, Zn, Ni from pulverized PCB waste procured from discarded computers from Delhi and Kanpur. The efficiency of Cu (95%) within 12 days under pH 2.0, 30 °C, and 10% pulp density advocates the full-scale practice of bioleaching [207]. Further, the hydrometallurgical technique after acid pretreatment of PCBs to remove base metals, followed by thiourea leaching, was proved to be effective for gold recovery, which yielded up to 88.5% gold recovery within 3 h under mixing conditions involving 0.5 M thiourea and 0.01 M Fe³⁺ as an oxidant [208]. A techno-economic evaluation by them also revealed that bio-hydrometallurgical processing could decrease capital investment by 35% compared to pyrometallurgical alternatives, with the added advantage of minimizing emission of dioxins and heavy metals. The microbial processes also co-align with India’s prominence on promoting low-carbon and efficient resource-recovery techniques under the National Resource Efficiency Policy Draft [209]. Similar studies concluded that a combination of bioleaching and chemical leaching has the potential to further augment material recovery with less economic liability from low-grade e-waste—plausibly being suited for decentralized recycling units with limited thermal infrastructure [210,211]. Moreover, bioleaching and chemical leaching are practically feasible in current scenarios as predominant small-scale units cannot afford high-energy intensive techniques.

Regarding policy intervention in India, a recent case study by [212] in Bengaluru, India demonstrated beneficial impacts of EPR policy. Bengaluru—one of the largest e-waste-generating cities in India—generates ~20,000 tons of e-waste annually owing to clustered IT industries and tech company headquarters. In this city, more than 58 e-waste-producing entities, including major IT companies, have compelled EPR policies through the enforcement of producer responsibility organizations. The implementation of EPR as a compulsory rule led to a sudden increase in formal collection and e-waste recycling. In 2016, 2000 tons of e-waste was formally recycled which raised by 275% and attained 7500 tons in 2020. Similarly, the e-waste collection efficiency also enhanced from 10% to 37% from 2016 to 2020 [212]. Moreover, the development of decentralized e-waste collectors and processing units (E-parisaraa) experienced 8 times higher throughput levels from 1 tpd (2010) to 8 tpd in 2020. The impact of EPR has been socially and environmentally praised as formal recycling considerably decreased release levels of toxic metals and created ~1500 green employments reducing reliance on the informal sector [213].

Despite such advancements in technology and policy enforcement, socio-economic and environmental challenges exist as the informal sector still handles 60–70% of Bengaluru’s e-waste due to higher recovery prices, weak supervision, and localized profit demands [214]. However, EPR when effectively practiced with strict monitoring can improve e-waste processing, decrease environmental pollution, and create organized jobs in India’s urban centers with nationwide coordination and public engagements.

8.2. China

Over the decades, China transitioned from previously being the largest importer of e-waste and the dominant center of informal recycling to more technically progressed and structured recovery channels, primarily in provinces like Jiangsu and Guangdong. One of the most successful establishments of this paradigm hails from the renovation of Guiyu—once recognized for crude e-waste processing and open burning, into a consolidated e-waste industrial park by enforcement of the National Sword Policy 2017 [214]. At China’s Jiangsu Zhongkai Hi-Tech e-waste processing facility, advanced bioleaching and hydrometallurgical systems have been employed at a sub-industrial level to procure Cu, Au, and Pd from pulverized PCBs collected from household discarded televisions, monitors, and smartphones [215]. Bioleaching using the combination of Acidithiobacillus thiooxidans and A. ferrooxidans yielded around 92% Cu from shredded PCBs within 8–10 days at a pulp density of 10% and pH of 1.8–2.2 [216]. In this study, the daily 500–1000 kg of e-waste was fed in leaching bioreactors with combined pH and aeration control mechanisms. In another study, thiourea-based hydrometallurgical extraction yielded 96.4% gold recovery by employing 0.5 M thiourea and 0.1 M Fe³⁺ under mixing at 300 rpm and 25 °C [217]. The case study reported that the hydrometallurgical extraction plant operates in compliance with ISO 14001 standards [217] and China’s more stringent policy—WEEE Collection and Treatment Regulation 2015. Furthermore, environmental monitoring of bio-hydrometallurgical industrial and processing parks equipped with biological modeled reactors demonstrated a nearly 70% reduction in airborne Pb and Cd concentrations in surrounding areas for five years along with 40% lower process energy requirements, and 30% reduced capital costs than that of pyrometallurgical recovery systems [218]. Following this success story in China, other modular industrial parks such as Tianjin and Chongqing WEEE industrial parks emerged with the support of the Ministry of Ecology and Environment and private organizations, e.g., Tianqi Environmental Protection. These plants advocate enhanced practice of bio-hydrometallurgical recovery techniques for their high metal recovery efficiency, feasibility, and scalability under China’s regulatory mechanisms [215].

The case study conducted in Guiyu, Guangdong Province assessing e-waste management practices after enforcement of nationwide EPR policies and financial subsidy measures demonstrated a significant transformation in e-waste handling. Historically, Guiyu town was known for illegal and informal e-waste recycling, which significantly reduced after the introduction of amended policy interventions such as EPR, and WEEE management regulation 2009 (enforced in 2011) which mandated following producer-pays model and contribution to the national recycling fund by electronic manufacturers. This method promoted authorized formal recyclers by providing per-unit subsidies for category-wise e-waste processing. This model channelized direct financial profits and incentives to legal operators and formal recyclers, which motivated informal recyclers to integrate into formal systems [218]. In order to increase formal e-waste recycling practices, the Chinese government established the Guiyu Circular Economy Industrial Park with ¥1.5 billion of investment which centralized e-waste processing and promoted the integration of numerous informal recycling units—resulting significant increase in formal recycling units from 1.2 million (2015) to more than 7.2 million units (2020) with many in transition [219]. Such policy reform increased certified e-waste recyclers in 2020 which handled 1.7 million tons of e-waste with reference to 1.3 million tons in 2016 [220]. The environmental benefits were remarkable as Pb and dioxin levels in Guiyu’s soil and air decreased by 85% and 70%, respectively, between the years 2013 and 2019 [36]. The Guiyu case highlights the efficacy of financially supported EPR policies, infrastructure investment, and regulatory execution in transitioning from unauthorized to sustainable e-waste recycling.

Nevertheless, the challenges pertaining to e-waste recycling are still substantial because of the whopping generation rate, preference for localized household benefits, unawareness in marginalized communities, and higher purchase prices.

9. Conclusions and Perspectives

The review highlights the current scenario of e-waste generation, treatment, and regulations implemented or recommended across the globe for its systematic management. Summarily, a sense of concern must be instilled in different governments about the detrimental effects of improper e-waste disposal and processing, illegal transboundary movement, and weak enforcement of laws that fail to ensure the safety of human health and the environment. Conventional disposal pathways such as open burning and landfills should be replaced with advanced technologies such as biochemical and thermal plasma-assisted pathways to ensure the recovery of useful energy and resources (valuable metals, rare earth minerals, etc.) with minimum or zero impact on the ecosystems.

This paper presents a comprehensive review of recent advancements in both conventional methods (such as landfilling) and emerging treatment technologies (including biochemical and thermal plasma-assisted processes), evaluating their feasibility and effectiveness for resource recovery. The paper sheds light on the origins, composition, and categorization of e-waste and provides a critical analysis of its adverse effects on human health and the environment, aiming to inform strategies for mitigating its harmful impacts. The paper summarizes vital barriers that hinder successful policy enforcement with country-specific examples and enlightens on the possible solutions that can be implemented for policy reforms, particularly for developing countries. The review concludes that socio-economic and cultural variability considerably impact e-waste regulation enforcement depending upon country-specific social structure, preference, and awareness levels. The regulatory framework is deemed essential for safe, eco-friendly, and sustainable E-waste management; hence, the transboundary movement of e-waste and its effects on Sustainable Development Goals, international efforts, and regulatory frameworks are deeply examined to facilitate effective and sustainable valorization in specific regions. E-waste management presents significant promises for energy and resource recovery; yet, it is fraught with issues that must be addressed individually.

The challenge of safe e-waste management needs to be viewed as an impetus to innovate and create advanced methods for e-waste processing, focusing on the recovery of energy and valuable materials. Further research on metal reclamation is necessary for a comprehensive understanding and to guarantee their holistic and sustainable deployment. The establishment of new e-waste processing facilities and the expansion of current ones should be investigated, utilizing advanced technology alongside supportive governmental regulations. A collaborative endeavor among scientists, engineers, environmentalists, and policymakers is essential to guarantee sustainable e-waste processing for an environmentally benign future.