E-waste Recycling and Copper Recovery

• Electronic devices improve living standards but result in increased e-waste, posing environmental and health threats.
• Chemical leaching with aqua regia, a widely used method for e-waste metal recovery, is corrosive and hazardous.
• An iron-based leaching solution provides a safer, environmentally friendly approach to copper recovery from e-waste.
• Combining experimental procedures with computational modeling optimizes copper extraction from printed circuit boards (PCBs).

Experimental Procedure

• PCBs treated with iron-based solutions of varying concentrations tested for effectiveness over two time periods.
• 72.69% recovery rate achieved with a 50:50 ferrous and ferric sulfate mixture over five days.
• Python's SciPy library identifies 5.92 g of PCB as ideal input for the process.

E-waste Recycling Hubs in Dhaka

• Survey of Dhaka's primary e-waste recycling hubs, Nimtoli and Elephant Road, reveals that approximately 1173 tons of e-waste are processed annually.
• Experimental findings and survey data project over 35 million BDT annually through copper recovery.
• Unsafe handling practices endanger workers and the environment and hinder regulatory efforts.
• Stricter regulations, greater public awareness, and eco-friendly methods are needed to ensure safer, effective copper recovery.

E-waste Composition

• E-waste contains hazardous, non-hazardous, and valuable substances.
• Non-hazardous metals include copper (Cu), aluminum (Al), tin (Sn), manganese (Mn), and iron (Fe).
• Hazardous substances include sulfur (S), cadmium (Cd), beryllium oxide (BeO), brominated flame retardants, lead (Pb), lithium (Li), nickel (Ni), and mercury (Hg).
• Other hazardous materials include chlorofluorocarbons, organic substances, and radioactive substances.
• Non-metallic components of e-waste include plastic, glass, ceramics, and wood.

E-waste Metal Content

• Metallic fraction is over a quarter of organic and ceramic elements in waste electric and electronic equipment.
• Global demand has increased for precious metals (Pt, Au, Ag, Pd), base metals (Zn, Pb, Cu, Ni), and rare earth minerals (La, Ce, Nb) in electronic applications.
• E-waste contains over 60 different metals, considered valuable due to total metal content.
• The potential revenue of PCBs was $21,200/ton; an estimated 12.5 MT of recoverable Cu could have a market value of US$ 6.45 per kg.

Environmental and Health Risks

• E-waste contains metallic/non-metallic elements, posing environmental and health risks if not properly managed.
• Informal recycling practices lead to air, soil, water, and dust pollution from hazardous toxicants.
• Agbogbloshie (Ghana) and Guiyu (China) have elevated lead and other contaminants due to unsafe practices.
• Musculoskeletal issues, injuries, respiratory/cardiovascular symptoms, stress, hearing loss, hepatic damage, DNA damage, and epigenetic changes are health impacts from e-waste recycling.

Heavy Metal Pollution in the Lianjiang River

• Heavy metal pollution assessment reveals that arsenic (As) and strontium (Sr) pose developmental and reproductive risks to children.
• Carcinogenic risks are significant from As, chromium (Cr), and cadmium (Cd) through dermal absorption.
• E-waste contributes organic pollutants, including flame retardants, PAHs, PCBs, and dioxin-related compounds.
• PAHs are carcinogens that cause oxidative damage to DNA and lipid content.
• PCBs accumulate in breast milk.

Environmental Threats

• Informal e-waste recycling in Agbogbloshie (Ghana) causes heavy metal and organic pollutant contamination in soil/groundwater.
• High pollution degrees and ecological risks are observed at sites with elevated levels of antimony (Sb), Cd, Pb, and oil-related pollutants.
• Water quality is poor due to heavy metal pollution, with high levels of organic pollutants.
• Toxic dust particles are found in the ambient air.

Addressing E-waste Issues

• The strengthening of formal recycling processes is required.
• Enforcement of regulations to prevent illegal e-waste dumping is needed.
• The promotion of electronics design with longer lifespans and safer materials is important.
• Adherence to agreements like the Basel Convention is crucial.

E-waste Management in Bangladesh

• Global e-waste generation is rising rapidly impacting areas like Bangladesh.
• Only a small portion of e-waste is collected for recycling.
• Innovation and sustainability can transform the global challenge into an opportunity for positive change.

PCBs

• Printed circuit boards (PCBs) connect and support components in electronic devices.
• PCBs are made from epoxy resin or fiberglass coated with thin copper films.
• PCBs contain valuable metals like gold, silver, copper, and palladium; and hazardous substances like gallium arsenide, beryllium, and brominated flame retardants.
• Though PCBs are about 3% of total e-waste by weight, the contain valuable substances

Elemental Concentrations

• Routers have high levels of copper (216,333 ppm), aluminum (54,433 ppm), iron (50,500 ppm), and tin (35,200 ppm).
• Mobile phones have greater copper concentration (342,667 ppm) along with aluminum (19,068 ppm) and nickel (11,600 ppm).
• Smartphones have the highest copper content (395,000 ppm)

Top PCB Elements

• For routers, copper (Cu) constitutes 57.32% of the total concentration.
• For mobile phones, copper comprises 82.75% of total concentration.
• For smartphones, copper also dominates at 82.01% of the total concentration.

E-waste Management Techniques

• Solid waste management for e-waste involves landfilling, incineration, recycling, and reuse.
• Recycling enables recovery of valuable materials and reduces associated environmental impact.
• Metal recovery processes include mechanical processing, chemical leaching, bioleaching, pyrolysis, electrochemical, hydrometallurgical, and bio-metallurgical methods.

Leaching Methods

• Chemical leaching offers high metal recovery rates and preservation of metal quality.
• Common lixiviants like thiourea, thiosulfate, and aqua regia yield varying metal recovery rates.
• Cyanide leaching is effective but poses environmental and health risks.
• Halide leaching offers safer alternatives.

Aqua Regia and Alternative Leaching Agents

• Aqua regia effectively oxidizes metals but poses health hazards due to toxic gas release.
• Iron solutions can serve as less corrosive alternatives to mitigate environmental impact and allow for promising chemical leaching.

Bioleaching

• Microorganisms can extract metals.
• Microbes oxidize and dissolve metals, converting metal sulfides into soluble sulfates.
• Includes one-step, two-step, and spent-medium methods.

E-waste Collection in Dhaka

• Dhaka relies on a mix of formal and informal e-waste management.
• Approximately 70 shops in Nimtoli specialize in manual dismantling, sorting, and crushing e-waste.
• Shops in Elephant Road focus on repairing and reselling e-waste in addition to recycling.
• The survey estimates approximately 120 shops collect between 40 and 2000 kg of e-waste per month.
• Total monthly e-waste accumulation is about 97,750 kg, leading to combined yearly total of 1173 tons in surveyed areas.

Financials of Copper Recovrey

• The experiment achieved 43.77 wt% copper extraction from router PCBs using a 50:50 iron solution in 5 days.
• Approximately 1173 tons of e-waste from surveyed areas could yield about 31 tons of copper.
• Recovered copper could generate more than 35 million BDT annually.

E-waste Management Regulation

• Only 3-5% of e-waste is formally processed, with the remainder going to landfills.
• In Bangladesh shops accumulating and treating e-waste operate under unregulated conditions.
• Regulatory measures and enforcement are needed to improve e-waste management and protect the environment.
• The 'E-waste Management Rules' provide a regulatory framework, promote extended producer responsibility, and aim to build dedicated recycling facilities.

Conclusions of Study

• Optimized chemical leaching offers a greener alternative to traditional metal recovery methods.
• Mixing ferrous and ferric sulfate (1:1) is the most effective leaching agent
• E-waste recyclers should have education about handling e-waste and wear protective gear, as well as the rules being enforced.