Environmental Impact of Processing Electronic Waste – Key Issues and Challenges

Extensive utilization of electric and electronic equipment in a wide range of applications has resulted in the generation of huge volumes of electronic waste (e-waste) globally. Highly complex e-waste can contain metals, polymers and ceramics along with several hazardous and toxic constituents. There are presently no standard approaches for handling, dismantling, and the processing of e-waste to recover valuable resources. Inappropriate and unsafe practices produce additional hazardous compounds and highly toxic emissions as well. This chapter presents an overview of the environmental impact of processing e-waste with specific focus on toxic elements present initially in a variety of e-waste as well as hazardous compounds generated during e-waste processing. Hazardous constituents/ and contaminants were classified in three categories: primary contaminants, secondary contaminants, and tertiary contaminants. Primary contaminants represent hazardous substances present initially within various types of e-waste; these include heavy metals such as lead, mercury, nickel and cadmium, flame retardants presents in polymers etc. Secondary contaminants such as spent acids, volatile/toxic compounds, PAHs are the by-products or waste residues produced after inappropriate processing of e-waste and the tertiary contaminants include leftover reagents or compounds used during processing. A detailed report is presented on the environmental impact of processing e-waste and the detrimental impact on soil contamination, vegetation degradation, water and air quality along with implications for human health. Challenges and opportunities associated with appropriate e-waste management are also discussed

A Novel Recycling Approach for Transforming Waste Printed Circuit Boards into a Material Resource

AbstractThe recovery of materials from urban waste has become progressively more important with wastes providing a variety of resources. This study focuses on the recycling of electronic printed circuit boards (PCBs) from mobile phones, computers, TVs, white goods, and micro-processors etc. that contain significant amounts of hazardous/toxic components along with a variety of metals, ceramics and polymers. Both formal and informal sectors are engaged worldwide in recycling such e-waste to recover precious and other metals (upto 40-70% of value). However poor recycling techniques, especially in developing countries, generate high levels of environmental pollution that affects both the ecosystems and the people living within or near the main recycling areas. Various e-waste recycling methods used in the informal sector include manual dismantling, open burning of PCBs, plastic chipping and melting, burning wires to recover copper, acid & cyanide salt leaching, and inadequate metallurgical treatments. These activities release dust particles loaded with heavy metals and flame retardants into the atmosphere that may re-deposit near the emission site, or be transported over long distances depending on their size. Significant levels of environmental pollution are thus associated with recycling e-waste.This study presents an environmentally sustainable solution to e-waste management and reducing associated pollution during recycling. In this study, waste PCBs were heat treated in the temperature range 1150-1350oC for periods of up to 20minutes in an Argon atmosphere. Key metallic constituents namely Cu, Sn and Pb showed a tendency to segregate out in the form of copper rich and Sn rich metallic balls. Minor elements such as Al, Fe, Mg, Ni, Pd, Pt and Zn segregated along with metallic droplets. Such high temperatures led to the removal of hazardous lead and the recovery of highly concentrated copper alloys and precious metals. Pyrolysis of PCBs also generated a carbon rich residue containing traces of Sn and very low levels of copper. Various ceramic impurities present precipitated out as slag and did not interfere with metal recovery