Resource Recovery and Solid Waste Treatment

27. What are the functions of a Material Recovery Facility (MRF)?

A Material Recovery Facility (MRF) plays a crucial role in solid waste management by sorting
and processing recyclable materials. Its primary functions include:

1. Sorting and Separation: MRFs use manual and automated processes to separate
recyclable materials like paper, plastics, metals, and glass from mixed waste streams.
2. Processing: Once sorted, materials are processed (e.g., crushed, baled, or shredded) to
prepare them for recycling or resale.
3. Quality Control: MRFs ensure that recovered materials meet quality standards for
recycling by removing contaminants.
4. Resource Recovery: By recovering valuable materials, MRFs reduce the amount of
waste sent to landfills and promote resource conservation.
5. Economic Benefits: MRFs generate revenue by selling recovered materials to
manufacturers and recycling industries.
6. Environmental Protection: By diverting waste from landfills, MRFs help reduce
greenhouse gas emissions and environmental pollution.

28. How materials can be recovered from the drop-off center and buy-back center.

Materials can be recovered from drop-off centers and buy-back centers through the following
processes:

1. Drop-Off Centers:
o Residents bring recyclable materials (e.g., paper, glass, plastics) to designated
locations.
o Materials are sorted by type and stored in separate containers.
o Collected materials are transported to MRFs or recycling facilities for further
processing.
2. Buy-Back Centers:
o Individuals bring recyclable materials to the center and are paid based on the
weight or quantity of materials.
o Materials are sorted, weighed, and processed on-site or sent to MRFs.
o This incentivizes recycling and ensures a steady supply of recyclable materials.

Both systems rely on public participation and efficient logistics to recover materials for
recycling.

29. What types of materials are typically recovered from drop-off centers and buy-back
centers?
The materials typically recovered from drop-off centers and buy-back centers include:

1. Paper and Cardboard: Newspapers, magazines, office paper, and corrugated cardboard.
2. Plastics: Bottles, containers, and packaging materials (e.g., PET, HDPE).
3. Metals: Aluminum cans, steel cans, and other scrap metals.
4. Glass: Bottles and jars of various colors.
5. Electronics: Old computers, phones, and other e-waste (in some centers).
6. Textiles: Clothing and fabrics (in specialized centers).

These materials are sorted, processed, and sent to recycling facilities to be turned into new
products.

30. What are the differences between clean MRF and dirty MRF?

The differences between clean MRFs and dirty MRFs are as follows:

1. Clean MRF:
o Processes pre-sorted recyclable materials (e.g., from curbside recycling
programs).
o Materials are relatively free of contaminants.
o Focuses on separating and processing specific recyclables like paper, plastics, and
metals.
o Higher efficiency and lower processing costs due to less contamination.
2. Dirty MRF:
o Processes mixed solid waste (both recyclables and non-recyclables).
o Requires extensive sorting to separate recyclable materials from general waste.
o Higher contamination levels, leading to lower recovery rates and higher
processing costs.
o Often used in areas without source separation programs.

31. What are the different unit operations in solid waste treatment?

The unit operations in solid waste treatment include:

1. Collection and Transportation: Waste is collected and transported to treatment

facilities.
2. Sorting and Separation: Materials are separated manually or mechanically into
recyclables, organics, and residuals.
3. Shredding and Size Reduction: Waste is shredded to reduce volume and prepare for
further processing.
4. Composting: Organic waste is decomposed into nutrient-rich compost.
5. Incineration: Combustible waste is burned to generate energy and reduce volume.
 6. Landfilling: Non-recyclable and non-compostable waste is disposed of in engineered
landfills.
7. Recycling: Recovered materials are processed and turned into new products.

32. What is recycling, and why is it important in solid waste management?

Recycling is the process of collecting, sorting, and processing waste materials to create new
products. It is important in solid waste management because:

1. Resource Conservation: Recycling reduces the need for raw materials, conserving
natural resources like timber, water, and minerals.
2. Waste Reduction: It diverts waste from landfills, reducing the volume of waste and
extending landfill lifespans.
3. Energy Savings: Recycling consumes less energy compared to producing new materials
from raw resources.
4. Environmental Protection: It reduces pollution, greenhouse gas emissions, and the
environmental impact of waste disposal.
5. Economic Benefits: Recycling creates jobs in the recycling industry and generates
revenue from selling recovered materials.

33. What are the benefits of recycling for the environment, economy, and society?

The benefits of recycling are as follows:

1. Environmental Benefits:
o Reduces landfill waste and associated pollution.
o Lowers greenhouse gas emissions by reducing the need for energy-intensive
production processes.
o Conserves natural resources and protects ecosystems.
2. Economic Benefits:
o Creates jobs in the recycling and manufacturing industries.
o Generates revenue from the sale of recycled materials.
o Reduces waste management costs by diverting materials from landfills.
3. Social Benefits:
o Promotes environmental awareness and responsible consumption.
o Encourages community participation in sustainability efforts.
o Improves public health by reducing pollution and waste-related hazards.
 Final Disposal of Solid Waste
34. What are the environmental and health risks associated with open dumping?

• Environmental risks:
o Soil contamination due to hazardous waste leachate.
o Air pollution from decomposing waste and burning of plastics.
o Water pollution as toxins seep into groundwater and surface water.
• Health risks:
o Spread of infectious diseases due to exposure to hazardous waste.
o Breeding ground for pests such as mosquitoes and rodents.
o Respiratory problems from inhaling toxic fumes and particulate matter.

35. What are the different types of landfills, and how do they differ?

• Sanitary landfills: Engineered sites with liners and leachate treatment to prevent
contamination.
• Controlled dumps: Poorly managed but slightly better than open dumps with minimal
control measures.
• Open dumps: Unregulated disposal areas that cause severe environmental pollution.
• Hazardous waste landfills: Designed specifically for toxic and hazardous waste with
advanced containment systems.

36. What are the different methods of landfilling?

• Trench method: Waste is placed in trenches and covered with soil. Suitable for areas
with deep soil cover.
• Area method: Waste is spread and compacted above ground, covered with soil. Used in
areas with shallow soil.
• Cell method: Waste is placed in lined cells to prevent leachate and gas migration.

37. Draw a sectional view of a sanitary landfill

(A diagram should be included, showing layers such as liners, waste compacted in layers,
leachate collection system, gas collection system, and final soil cover.)

38. What factors need to be considered when selecting a landfill site?

• Environmental factors: Avoidance of water bodies, flood zones, and protected areas.
• Geological factors: Presence of stable soil and absence of high groundwater levels.
• Proximity to population centers: Should be far from residential areas to minimize
health impacts.
• Accessibility: Good transportation routes for waste collection trucks.
• Regulatory compliance: Must meet environmental and legal requirements.
39. What are the different phases of landfill gas generation?

• Phase 1: Aerobic decomposition – Organic waste breaks down with oxygen, producing
CO₂.
• Phase 2: Anaerobic acid phase – Oxygen depletes, and organic acids form.
• Phase 3: Methanogenesis – Bacteria break down acids, releasing methane and CO₂.
• Phase 4: Maturation phase – Gas production declines as waste stabilizes.

40. What factors affect landfill gas generation?

• Waste composition: Organic waste produces more methane.

• Moisture content: Higher moisture increases microbial activity and gas production.
• Temperature: Warmer temperatures accelerate decomposition and gas formation.
• Landfill design: Properly engineered landfills have better gas collection efficiency.
• Age of waste: Gas production declines over time as waste stabilizes.

Public Health, Environmental, and Safety Issues

41. What safety measures should be followed during the storage, transport, treatment, and disposal
of healthcare waste?

• Storage: Use designated, color-coded, and labeled bins for different types of waste (infectious,
sharps, chemical, radioactive). Store waste in leak-proof and puncture-resistant containers.

• Transport: Ensure proper sealing of waste containers. Use covered, dedicated vehicles for
transport. Follow route plans to avoid accidents and spillage.

• Treatment: Use appropriate methods such as autoclaving, incineration, chemical disinfection, or

microwaving based on waste type.

• Disposal: Ensure final disposal in designated sites like sanitary landfills or specialized treatment
facilities. Avoid open dumping or burning to prevent environmental pollution.

42. What are the different types of personal protective equipment (PPE) needed for waste
management tasks?

• Gloves: Protect hands from contamination and hazardous substances.

• Face masks & respirators: Prevent inhalation of harmful pathogens and dust.

• Protective clothing (gowns, coveralls): Shields the body from exposure to infectious waste.

• Eye protection (goggles, face shields): Prevents splashes and airborne contaminants from
entering the eyes.
 • Boots or closed-toe shoes: Protects feet from sharps and spills.

43. What are the potential risks associated with improper use of PPE in waste management?

• Infection and disease transmission: Exposure to hazardous and infectious materials can lead to
infections.

• Chemical exposure: Incorrect PPE use may result in exposure to toxic chemicals.

• Physical injuries: Lack of gloves or boots can cause cuts, punctures, or burns.

• Respiratory issues: Not using masks properly can lead to inhalation of harmful particles or
fumes.

• Cross-contamination: Incorrect disposal or reuse of PPE can spread contaminants.

44. How can efficient solid waste management practices help mitigate the effects of climate change?

• Reducing landfill waste: Proper recycling and composting decrease methane emissions.

• Waste-to-energy conversion: Generating energy from waste reduces reliance on fossil fuels.

• Reducing deforestation: Recycling paper and wood helps conserve forests.

• Lowering carbon footprint: Efficient waste collection and transport systems reduce fuel
emissions.

• Promoting circular economy: Reuse and recycling reduce the demand for new resource
extraction.

45. Discuss the impact of improper waste disposal on climate change and water pollution.

• Climate change:

o Landfills release methane, a potent greenhouse gas.

o Burning waste emits CO₂ and toxic gases, contributing to global warming.

• Water pollution:

o Leachate from landfills contaminates groundwater.

o Dumping waste into water bodies leads to toxic pollution affecting aquatic life.

o Chemical waste can make water unfit for drinking and agricultural use.

46. What are the environmental consequences of improper disposal of solid waste?

• Soil degradation: Hazardous chemicals seep into the soil, reducing fertility.

• Air pollution: Burning waste releases harmful gases, affecting air quality.

• Water contamination: Dumping waste in rivers and lakes leads to the destruction of marine
ecosystems.
• Threat to wildlife: Animals consume plastic waste, leading to health issues and death.

• Spread of diseases: Open dumping fosters breeding grounds for mosquitoes, rodents, and
bacteria.