Waste Management

Waste Management - SQA Key Definitions : 

• Circular economy - Products are designed to be completely reusable, with explicit planning on how the products can be returned to the point of origin and then remade, with nothing going to waste.

• Closed-loop recycling - A recycling process in which a product can be recycled indefinitely back into itself without any impact on its quality.

• Energy recovery - The incineration of waste in specialised facilities to generate electricity or heat. 

• Food use-by date - Dates applied to food representing the window of peak quality. Can be removed from a food product to reduce food waste. 

• Incineration - The burning of waste, either to generate energy in terms of 'waste recovery'  or as a 'waste disposal' technique. 

• Landfill - A disposal site for solid waste, in which the waste is placed in a lined hole in the ground, sealed and covered with topsoil. 

• Life cycle analysis - The examination of the total environmental impact of a product through every step of its life, from obtaining raw materials to disposal. 

• Linear economy -  Products are made from raw materials, sold to a consumer, and then become waste (usually in a landfill).

• Obsolescence - The process by which a product becomes unusable, outdated, or no longer desirable, leading to its disposal.

• Open-loop recycling - A recycling process in which a loss of quality often occurs with each recycling cycle, limiting the number of times the material can be recycled. 

• Planned obsolescence  - The deliberate shortening of a product's lifespan by the manufacturer to ensure consumers buy a replacement sooner.

• Psychological obsolescence - Occurs when a product is still perfectly functional, but the consumer is convinced it is 'outdated' through marketing and social pressure.

• Technological obsolescence - Occurs when a new technology is much better or cheaper than the old version, making the old version impractical.

• Waste disposal - The use of landfill or incineration without energy capture, as a final waste management option, when all other options have been exhausted. 

• Waste hierarchy - A ranking of waste management options according to what is best for the environment.

• Waste prevention - Techniques to prevent waste from being generated in the first place as part of waste management. 

• Waste recovery - Materials which cannot be recycled are incinerated in specialised facilities to generate electricity or heat.

• Waste recycling - The process of recovering materials from waste and processing the materials to form new products. 

• Waste reuse - The process of using an item again for its original purpose, instead of discarding or recycling it. 

Global Waste Production

Waste is generated through the production of goods and the consumption of goods. There is usually waste in all parts of the manufacturing process.

As discussed previously, the global Human population has increased massively in recent times. This has put huge pressure on waste management, as the increased population will inevitably produce more waste : 

Life Cycle Analysis (LCA)

'Life Cycle Analysis' examines the total environmental impact of a product through every step of its life, from obtaining raw materials to disposal. 

It is a systematic process, identifying and quantifying all inputs (materials, energy, fuels) and outputs (products, waste, emissions) for a whole life cycle or for individual stages. Manufacturers can then evaluate the results and consider where changes might be made. 

The diagram below shows a 'Life Cycle Analysis' of a cotton t-shirt (within the box), showing the inputs & waste at each stage (outside the box) :  

Circular and Linear Economic Models

In traditional production, the path taken by a product is known as a 'Linear Economy'. The product is made from raw materials, sold to a consumer, and then becomes waste (usually in a landfill). This method of production is unsustainable and is now being addressed by looking to move towards a much more sustainable path, known as a 'Circular Economy'. 

In a 'Circular Economy', all products are designed to be completely reusable, with explicit planning on how the products can be returned to the point of origin and then remade, with nothing going to waste. 

Below are two examples of the Circular Economy in action within Scotland :

Waste Management : The Role of SEPA

Waste management activities in Scotland are regulated by SEPA to prevent pollution and harm to human health. SEPA regulates these activities through a system of licences and permits. If a company wishes to dispose of waste, it has to be done in a regulated way, it cannot just be dumped or released into the environment. 

The videos below show an overview of SEPA, as well as a summary of a multi-agency project on waste management and waste crime that SEPA is a part of:-

Waste Generation : Globalisation of Supply Chains

The globalisation of supply chains has acted as a double-edged sword: while it has driven down costs and increased the variety of goods available, it has fundamentally transformed waste generation from a local management issue into a complex, international issue. 

There are three main issues for waste generation in terms of globalisation : 

• Long Distance Food Wastage - Roughly 13% of food globally is lost between harvest and the retail shelf. Long-distance shipping reduces the shelf-life of a product due to transit time, as well as the risk of temperature fluctuations and handling errors, increasing food waste. 

• Protective Packaging - Products travelling across continents require multiple layers of protection, much of which is non-recyclable plastic. Plastic packaging accounts for ~33% of all plastic waste globally. 

• 'Pollution Haven' Effect - Polluting industries can relocate their production to jurisdictions with weaker environmental regulations to reduce compliance costs.

The diagram below shows the extensive supply chain required for the manufacturing of semiconductor chips, waste will be generated at each point, including transport between : 

Waste Generation : Obsolescence

Obsolescence is the process by which a product becomes unusable, outdated, or no longer desirable, leading to its disposal. 

There are three key types of obsolescence : 

• Technical Obsolescence - Occurs when a new technology is much better or cheaper than the old version, making the old version impractical.

• Planned Obsolescence - The deliberate shortening of a product's lifespan by the manufacturer to ensure consumers buy a replacement sooner.

• Psychological Obsolescence - Occurs when a product is still perfectly functional, but the consumer is convinced it is "outdated" through marketing and social pressure.

All of these present a problem as all three cause waste to be generated.

Waste Generation : Packaging

Packaging is used to facilitate the transport and storage of products and to protect them from damage. It is used to display products such as food and technological gadgets. Packaging protects against unnecessary waste through product damage, but is itself considered waste. 

Packaging is the source of ~40% of all plastic waste generated, with nearly 142 million tonnes of plastic packaging waste generated in 2019 alone :  

Pressure from government and society is forcing the packaging industry to consider how its products can be made more sustainable. 

In addition to reducing the volume of packaging, focus is on use of renewable energy in sourcing, manufacturing, transporting and recycling processes; use of renewable or recycled source materials; and amending production practices.

Waste Generation Case Study : Bioplastic 

When most people think of plastic, they are thinking of plastic made from Crude oil. But the definition of 'Plastic' in chemistry is much wider than that. 

A Plastic is defined as:-

"A synthetic or natural substance that is made from a Polymer (a repeating chain of small molecules)  that can be molded into a new fixed shape." 

Examples of natural polymers (natural plastics)  are:-

• Spider Silk (used for making webs)

• Keratin (makes the structure of nails/horns) 

• Latex (Sap of the Rubber tree) 

• Cellulose (makes the structure of plant material)

By looking to biological sources for plastics, plastic production can be made more sustainable, as these plastics will biodegrade in the environment and do not require fossil fuels (as a raw material at least) to produce. Any 'Plastic' made from a biological source is known as a 'Bio-Plastic'. 

Bio-Plastics can be made from a wide range of natural sources : 

Bio-Plastics support a sustainable 'circular' economy as any waste produced is used as nutrients for the growth of further raw materials :

The videos below show examples of specific products that are being produced using Bio-Plastics :

Waste Hierarchy

The 'Waste Hierarchy' is a ranking of waste management options according to what is best for the environment :

The waste hierarchy moves from prevention (the best choice) down to disposal (the last resort). 

Prevention

The best way to manage waste is to never create it in the first place. This can involve creating products that use fewer raw materials, choosing items with minimal packaging, removing unnecessary life limits (such as 'use-by' dates), educating, and acting to prevent obsolescence. 

Reuse

Before an item is discarded or recycled, it should be used again for its original purpose. This can involve using refillable glass bottles, donating clothes to second-hand stores, or repairing equipment instead of buying new. This can be as a whole item or the refurbishment and reuse of parts. This saves the energy and emissions that would be required to manufacture a new product.

Recycle

If an item cannot be reused, its materials should be recovered and processed into new products. This can involve melting down plastic to make new products, composting waste food or processing scrap metal. While better than simply disposing of the item, recycling is energy-intensive and the resulting products may not be of the same high quality as the newly made item. 

There are two distinct types of recycling : 

• Open Loop Recycling - In open loop recycling, a loss of quality often occurs with each recycling cycle, limiting the number of times the material can be recycled. An example is plastic, which is reprocessed into a lower-grade product each time. Eventually, it will not be recyclable and will become waste.

• Closed Loop Recycling - In closed loop recycling, a product can be recycled indefinitely back into itself without any impact on its quality. An example is aluminium. Recycling aluminium requires approximately 5% of the energy needed to produce it from bauxite, reducing waste, resource depletion, and anthropogenic greenhouse gas emissions.

Recovery (Energy) 

When materials cannot be recycled (like certain contaminated plastics or organic waste), they are often incinerated (burned) in specialised facilities to generate electricity or heat, in a process known as 'Waste-to-Energy'. This is better than a landfill because it captures some value, but it is still lower on the hierarchy because the original material is destroyed and can no longer be used in the economy. WtE schemes also must deal with the carbon dioxide produced in the burning process, as well as any other toxic gases generated. 

Disposal

This is the bottom of the pyramid, the least environmentally friendly option. This should only be done as a last resort, when all other options above have been exhausted. 

There are two distinct types of disposal : 

• Incineration without energy recovery - The burning of waste where the heat is simply vented into the atmosphere as a disposal technique is highly polluting, due to the waste gases generated. Also, the ash that remains is high in heavy metals and other contaminants, so it must then be sent to a landfill itself. 

• Landfill - Traditionally, waste is just dumped into a large hole in the ground, then covered with topsoil, though this process will have a range of impacts on the environment. In a modern landfill site, the bottom and sides are lined with compacted clay and high-density plastic to prevent leachate (a waste chemical-laden fluid) from seeping into the water table. A network of pipes collects the liquid that drains through the waste. This liquid is then pumped out and treated like industrial sewage. At the end of each day, it is covered with soil or foam to reduce odours and prevent pests (birds, rats, etc.) from spreading disease. Once full, it is sealed with an impermeable cap and covered with soil and vegetation to prevent rainwater from entering.

While the 'Waste Hierarchy' places it at the very bottom, landfills remain the most common waste management method globally, at ~38% of all waste going to landfills. The graph below shows the waste sent to landfills in the U.S. alone : 

Impact of Waste on the Environment

As human populations have increased, so has the amount of waste that is entering the environment. Waste can come from many sources and cause damage to a wide variety of ecosystems, sometimes thousands of miles from their source. 

Land Pollution Case Study : Clothing Waste 

For humans, clothing serves as a versatile tool that helps us adapt to our environment, protect or express ourselves, and connect with others. As human society evolved, the uses of these materials changed as Humans developed ways to improve the natural properties of the materials, such as improving strength or versatility. This includes processes such as the spinning of cotton or the weaving of flax to make linen. In modern times, the invention of plastic fibres for clothing such as polyester, nylon and elastane has led to numerous environmental issues, as these do not degrade naturally, unlike traditional fibres. 

While the technology exists to recycle almost every type of plastic fibre, less than 1% of clothing is recycled into new clothing, with ~80% globally going to landfill. Even when recycled, most 'recycled' textiles are actually downcycled into lower-value items like car insulation, mattress stuffing, or industrial rags. 

One of the major environmental issues in the global clothing market is the illegal dumping of clothing. The Atacama Desert in Chile is home to one of the world's largest illegal textile dumps, consisting of mountains of discarded clothing that are actually visible from space. Every year, ~60,000 tonnes of used and unsold clothing arrive at the port of Iquique, with ~39,000 tonnes being dumped illegally in the desert because they are unsellable or local landfills refuse them due to chemical toxicity. Most of the clothing is from Western 'Fast Fashion' brands (H&M, Zara, Shein, etc.) and over 60% are synthetic (polyester/nylon), meaning they are essentially plastic and will take up to 200 years to biodegrade : 

Air Pollution Case Study : Particulate Matter (< 2.5 µm)

In waste gas emissions, microscopic particles of whatever is being burnt is released. Of particular concern to health is particles that are smaller than 2.5 micrometers in size (PM2.5). This particulate matter is so small can penetrate deep into the alveoli of the lungs and can cause short-term health effects such as eye, nose, throat and lung irritation, as well as effect lung function and worsen medical conditions such as asthma and heart disease.

The two images below show the atmospheric carbon monoxide concentration at sea level for East Asia & North America on the 23rd of March 2023 :

In Northern China on the 23rd of March 23, the PM2.5 particulate level was 84 µg per cubic meter. This is more than 7 times higher than the 'clean air limit' and is at a level at which the risk of aggravation to the heart and lungs of the general public (not just those with sensitivities) is increased. 

Water Pollution Case Study : Marine Plastic Waste

When first invented, Plastic was seen as a 'wonder material', something with nearly infinite applications, cheap and easy to produce, durable and long-lasting. But it is these very properties that make plastic so polluting in our environment. 

Plastic waste in the marine environment presents a high level of impact, including :

• Plastic Consumption -  Animals often mistake colourful plastic fragments or floating bags for prey (like jellyfish). This leads to 'false fullness', where the stomach is physically full of indigestible material, causing the animal to starve to death despite having a full stomach.

• 'Ghost Fishing' - Discarded or lost plastic fishing nets continue to trap marine life, killing hundreds of thousands of whales, seals, and turtles annually. 

• Microplastics - Microplastics absorb Persistent Organic Pollutants (POPs) from the surrounding seawater. When a small organism eats the plastic, these toxins enter its tissues. Also, many plastics contain additives like BPA and Phthalates, which are known as 'endocrine disruptors'. In marine species, these have been linked to reduced fertility and developmental abnormalities

Once plastic enters the environment, it can take 100s of years (if ever) to fully decompose. The diagram below shows some of the average decomposition times from common products in the ocean : 

Even once a plastic product has 'decomposed', it still exists in the form of 'Micro-Plastics', fragments of plastic smaller than 5mm in size. The potential risks to living organisms due to microplastics are not well understood and are an area of current research. What is known is that microplastic contamination can be found everywhere in the environment : 

The diagram below  further shows the extent of the Plastic Waste issue :