Waste & Recycling: Environmental Biology Study Notes

Waste & Recycling

Introduction to Solid Waste

Solid waste refers to any discarded material that is not liquid or gas. Understanding the types, sources, and management of waste is essential for environmental biology and sustainability.

• Definition: Solid waste includes household garbage, industrial waste, mining byproducts, and agricultural residues.

• Categories: Waste is classified as Biotic (organic, derived from living organisms) and Abiotic (inorganic, non-living sources).

• Examples: Biotic waste includes food scraps and yard trimmings; abiotic waste includes plastics, metals, and glass.

Global and Canadian Waste Production

Waste production is a major global issue, with billions of tonnes generated annually. Canada contributes significantly to this problem through municipal, industrial, and agricultural activities.

• Global Municipal Solid Waste (MSW): Over 2 billion tonnes produced annually worldwide.

• Canadian MSW: Canadians produced 36.5 million tonnes in 2022, with per capita disposal decreasing by 11% from 768 to 684 kg.

• Mining Waste: Includes tailings, waste rock, and mine byproducts. Oil sands production generates large amounts of toxic tailings.

• Agricultural Waste: Includes plastics (bale wrap, grain bags), manure, and crop residues.

Types and Sources of Waste

Waste can originate from various sectors, each with unique environmental impacts and management challenges.

• Industrial Waste: Byproducts from manufacturing and resource extraction.

• Mining Waste: Tailings, waste rock, and chemical residues.

• Agricultural Waste: Manure, crop residues, and plastic products.

• Municipal Waste: Household garbage, recyclables, and compostables.

Mining Methods and Environmental Effects

Mining produces significant waste and environmental impacts. Different mining methods have varying degrees of ecological damage.

• Solution Mining: Involves injecting fluids to dissolve minerals for extraction. Used for salts and fertilizers.

• Strip Mining: Removes surface layers to expose horizontal mineral deposits. Overburden is replaced after extraction.

• Open-Pit Mining: Large holes are dug to access widely distributed ore.

• Subsurface Mining: Underground extraction, often more dangerous and environmentally damaging.

• Placer Mining: Uses water to separate heavy minerals from river sediments.

• Environmental Effects: Acid drainage, water pollution, habitat destruction, and greenhouse gas emissions.

Waste Management Strategies

Effective waste management reduces environmental impact and conserves resources. Strategies include reduction, reuse, recycling, and responsible disposal.

• 5Rs Approach: Refuse, Reduce, Reuse, Recycle, Rethink.

• Product Design: Manufacture products to use less material, last longer, and be easier to repair or recycle.

• Zero Packaging: Promote products with minimal or no packaging.

• Government Policies: Bans on single-use plastics and incentives for recycling.

Methods of Waste Disposal

Waste disposal methods vary in effectiveness and environmental impact. The main methods are landfilling, incineration, and shipping.

• Landfilling: Most common method; waste is buried in lined pits. Risks include leachate, methane production, and groundwater contamination.

• Incineration: Burns waste to reduce volume and generate energy. Produces air pollution and toxic ash.

• Shipping: Exporting waste to other countries, often with environmental justice concerns.

Recycling and Composting

Recycling and composting are key to diverting waste from landfills and reducing environmental impact.

• Recycling: Converts waste materials into new products. Includes open-loop (different products) and closed-loop (same product) recycling.

• Composting: Decomposes organic waste to produce humus, improving soil quality and reducing landfill use.

• Biogas Production: Anaerobic digestion of organic matter produces methane for energy and fertilizer.

Hazardous Waste and Detoxification

Hazardous waste contains toxic chemicals and requires special handling and treatment to prevent environmental harm.

• Sources: Household cleaners, automotive fluids, pesticides, batteries.

• Detoxification Methods: Physical separation, chemical treatment, bioremediation (using bacteria or enzymes).

• Example: Phytoremediation uses plants to absorb toxins from soil and water.

HTML Table: Comparison of Mining Methods

The following table compares major mining methods and their environmental impacts.

Mining Method	Description	Environmental Impact
Solution Mining	Inject fluids to dissolve minerals	Water contamination, subsidence
Strip Mining	Remove surface layers	Habitat destruction, erosion
Open-Pit Mining	Dig large holes for ore	Landscape alteration, acid drainage
Subsurface Mining	Underground extraction	Acid drainage, worker safety risks
Placer Mining	Separate minerals from river sediments	Water pollution, sedimentation

Key Equations and Concepts

• Greenhouse Gas Emissions: Waste decomposition produces methane ($CH_4$) and carbon dioxide ($CO_2$).

• Acid Drainage Reaction: $2FeS_2 + 7O_2 + 2H_2O \rightarrow 2Fe^{2+} + 4SO_4^{2-} + 4H^+$

• Biogas Production: $C_6H_{12}O_6 \rightarrow 3CO_2 + 3CH_4$ (Anaerobic digestion of glucose)

Summary Table: Waste Management Methods

Method	Advantages	Disadvantages
Landfilling	Low cost, large capacity	Leachate, methane, slow decomposition
Incineration	Reduces volume, energy recovery	Air pollution, toxic ash, high cost
Recycling	Resource conservation, pollution reduction	Requires sorting, contamination issues
Composting	Improves soil, reduces landfill use	Limited to organic waste, odor issues
Shipping	Reduces domestic waste	Environmental justice concerns

Conclusion

Waste management is a critical aspect of environmental biology, requiring integrated approaches to reduce, reuse, recycle, and responsibly dispose of waste. Understanding the sources, impacts, and treatment methods is essential for sustainable development and environmental protection.