Resource Recycling Methods

• Our world faces increasing waste, environmental pollution, and depletion of natural resources.
• Resource recycling helps solve these issues and achieve sustainable development.
• Resource recycling is the process of reusing materials and converting them into new products or energy instead of disposing of them as waste.

Methods of Resource Recycling

• There are several methods to recycle resources including mechanical, energy and chemical recycling.

Mechanical Recycling

• Mechanical recycling is the most common method worldwide.
• It involves collecting non-decomposed remains of materials.
• The collected materials are re-introduced into the same industry for manufacturing.
• It is used to obtain a new product of the same type of used remains.
• Recycling fabric and plastic scraps is an example of mechanical recycling.
• Separated, non-decomposed remains of substance are collected.
• These remains are cut into flakes.
• Pellets are obtained from the flakes.
• Pellets are used to obtain new products.
• Glass recycling is another example of mechanical recycling.
• Glass waste is collected and ground.
• The ground glass is melted in special furnaces.
• The melted glass is reshaped into new products.
• Aluminum recycling is a third example of mechanical recycling.
• Bauxite is extracted from aluminum using electrolytic cells, which requires high electrical energy.
• Used aluminum is melted and reshaped during recycling, requiring less energy than producing aluminum from bauxite.
• Resource recycling reuses energy already present in raw materials.
• Recycling aluminum saves about 95% of the energy required to produce aluminum from bauxite ore.
• Energy saved when recycling a specific product instead of producing it from raw materials is called conserved energy.
• Conserved energy = Energy used in original production - Energy used in recycling.
• Producing 1 ton of aluminum from raw materials requires 15000 kWh and recycling the same amount requires 750 kWh.
• The amount of conserved energy is 14250 kWh (15000 kWh - 750 kWh).
• The percentage of conserved energy is 95% ((14250/15000) x 100).

Energy Recycling

• Energy recycling is when solid waste such as plastic is burned as fuel to generate heat energy.
• This heat is used in power plants to generate electrical energy.
• The heat can also be used for warming buildings.
• Energy recycling reduces waste amounts and restores energy.
• Energy recycling results in negative impacts such as air pollution from burning waste.
• Burning or heating requires restricted procedures to reduce harmful emissions.

Chemical Recycling

• Chemical recycling is a process where waste is decomposed into main components using chemical reactions to obtain new substances or energy.
• Chemical processes include chemical decomposition, chemical neutralization, pyrolysis, and biochemical reaction.
• Chemical decomposition separates precious metals like gold and copper from electronic waste using chemicals like acids.
• Acids or bases decompose expired drugs into harmless substances.
• Chemical neutralization is a chemical reaction that neutralizes acids or bases in chemical waste to produce a neutral solution.
• Hydrochloric acid (HCl) can be neutralized by basic substances like sodium hydroxide (NaOH) to form sodium chloride (NaCl) which is called "complete neutralization reaction"
• Sodium carbonate (Na₂CO₃) to form a neutral solution of sodium chloride (NaCl) and carbon dioxide gas is evolved.
• Pyrolysis is used to recycle solid waste like organic or plastic waste.
• This process heats waste to high temperatures in the absence of oxygen, leading to decomposition.
• Products of pyrolysis include low density liquids (bio-oils), combustible gases, and solid materials.
• Solid materials produced during pyrolysis can be a source of energy or raw materials in other industries.
• Biochemical reaction uses living organisms or enzymes to convert organic waste into usable materials like fertilizer (compost) and biofuel.
• Biodegradation (bio-decomposition) converts organic waste (food scraps) into fertilizer through chemical reactions with microorganisms.
• Specific bacteria can convert organic waste into biofuels such as ethanol.

Effect of Recycling Processes in Keeping Ecological Balance

• Resource recycling has positive impacts on the environment.
• It reduces the consumption of natural resources.
• It reduces the need to extract new raw materials, decreasing environmental impact from mining.
• It reduces the amount of waste dumped in landfills.
• It limits environmental pollution.
• It maintains the health of ecosystems and biodiversity.
• Recycling 1 ton of paper protects 17 trees.
• Recycling 1 ton of paper saves 70% of the energy needed for the same amount of new paper.
• Recycling 1 ton of paper saves 85% of the water required for the same amount of new paper.
• If all newspapers were recycled, it would reduce about 20 million tons of carbon dioxide emissions annually, equivalent to removing 5 million cars.