================================== DOCUMENT 7: SESSION 7 (S7) ================================== POLLUTION ABATEMENT (21CHO105T) Unit 2 - Session 7 I. MULTIPLE CHOICE QUESTIONS (MCQs) 1. Manual dismantling of e-waste involves: ● Answer: B. Separating components by hand ● Explanation: Manual dismantling involves safely disassembling electronic equipment by hand to recover valuable parts, circuit boards, and reusable components. 2. Mechanical processing of e-waste includes: ● Answer: B. Shredding and separation ● Explanation: Mechanical processing utilizes industrial shredders followed by magnetic, density, and eddy current separation to recover metals and plastics from crushed e-waste. 3. Magnetic separation in e-waste processing is used to recover: ● Answer: C. Ferrous metals ● Explanation: Powerful magnetic overband separators extract iron and steel (ferrous metals) from shredded e-waste streams. 4. Chemical recycling of plastics mainly aims to: ● Answer: B. Break polymers into basic chemicals ● Explanation: Chemical (feedstock) recycling depolymerizes plastic waste into basic monomers and chemical petrochemical feedstocks for new polymer synthesis. 5. Pyrolysis of plastic waste produces: ● Answer: C. Fuel oil, gas, and char ● Explanation: Pyrolyzing plastic waste in oxygen-free reactors breaks polymer chains down into valuable liquid fuel oil, combustible gases, and solid carbon char. II. SHORT ANSWER QUESTIONS 1. What is e-waste and why does it require special processing? ● Answer: ○ Definition: E-waste (electronic waste) encompasses discarded electrical and electronic equipment (computers, phones, appliances). ○ Need for Special Processing: E-waste contains toxic heavy metals (lead, mercury, cadmium, beryllium) and persistent organic pollutants alongside valuable precious metals (gold, silver, copper). Special processing prevents toxic environmental leaching while enabling safe resource recovery. 2. Why is plastic waste processing important? ● Answer: Plastic waste is highly persistent in natural environments, causing severe terrestrial and marine pollution. Processing plastic waste through mechanical recycling, chemical depolymerization, or energy recovery conserves petrochemical resources, reduces landfill accumulation, and prevents microplastic pollution. III. LONG ANSWER QUESTION 1. Explain the processing methods used for e-waste management. ● Answer: 1. Collection and Pre-sorting ● Systematic collection of discarded electronic goods and manual sorting into distinct equipment categories (IT equipment, consumer electronics, white goods). 2. Manual Dismantling ● Removal of hazardous components (batteries, cathode ray tubes, capacitors) and recovery of high-value reusable parts, wiring, and circuit boards by hand to prevent contamination and damage. 3. Mechanical Shredding and Size Reduction ● Passing dismantled electronic scrap through heavy-duty industrial shredders to liberate constituent materials (metals, plastics, glass). 4. Physical and Chemical Separation Techniques ● Magnetic Separation: Removing iron and steel. ● Eddy Current Separation: Separating aluminum and non-ferrous metals. ● Density and Air Classification: Separating light plastics from heavy metallic fractions. ● Hydrometallurgical & Pyrometallurgical Refining: Utilizing acid leaching, solvent extraction, or smelting to recover precious metals (gold, silver, palladium, copper) from electronic circuit boards.