Each year, the global economy produces more than one billion tons of solid waste, composed primarily of paper, plastics, metals, organics,and many other by-products. Today, we generate more annual waste than ever before. By 2025, global waste generation is expected to grow by an additional 70%, driven in large part by growing populations, rising median incomes, and the accelerating pace of urbanization.

Though waste management efforts have significantly improved over the past 40 years, there are still many opportunities for improvement. Traditionally, solid wastes are discarded after use, and disposed to the environment. Treatment of solid wastes eventually evolved from a reactive approach to management of wastes. A similar linear economy model that was conventionally followed by manufacturers and industrial processes is described as the “take-make-dispose”approach. However, the improper disposal of solid wastes results in pollution, and causes diverse and adverse environmental and health effects.

Recent efforts to improve waste management practices are often limited to better treatment of waste through prominent principles like the 3Rs (Reduce, Reuse, and Recycle). These efforts do not maximize the potential value of solid waste. In contrast to improved waste management or treatment practices that still send resources to landfills, circular economy principles seek to maximize the use value of materials through the creation of a closed-loop economy.

Significant Value in Solid Waste

One person’s waste may be another person’s useful material. Or a product such as a mobile phone that is already at the end-of-life for certain users can still be used by another user. These solid wastes can either be a resource or a pollutant, or both. For example, lead found in computer circuit boards can be recycled to recover the lead, or it can contaminate the environment if left untreated. There are local governments and businesses which have started to consider end-of-life products as secondary resources. For example, in recent years, e-wastes have been receiving attention as secondary sources of metals because they contain precious metals (e.g., gold, silver and palladium) and special metals (e.g. indium, selenium, tellurium, tantalum, bismuth and antimony).

Circular Economy

According to the Ellen MacArthur Foundation (EMF), Circular Economy (CE) is defined as “an industrial system that is restorative or regenerative by intention and design; it replaces the‘end-of-life’ concept with restoration, shifts towards the use of renewable energy, eliminates the use of toxic chemicals, which impair reuse, and aims for the elimination of waste through the superior design of materials, products,systems, and within this, business models”

Moreover, circular economy principles have the potential to significantly reduce our use of natural resources despite the growing global population. Research from the Ellen MacArthur Foundation and the McKinsey Center for Business and Environment estimates that if the world transitioned to a circular economy, we could reduce consumption of new materials by up to 32% within 15 years and more than 50% by 2050.

Solid Waste Generation

Solid waste generation and management are closely tied to fundamental changes in the global environment and economy. Rising or highly variable raw materials costs, combined with increased consumer demand for more environmentally friendly products, have driven companies to improve their waste management practices. These linkages have given rise to the increased emphasis placed on effective waste management strategies as a means to improve companies’ bottom line. Key trends driving the increase of global solid waste include:

1. Urbanization: Urban residents produce about twice as much waste as their rural counterparts since they are, on average, wealthier and purchase more.
2. Competition for natural resources: Scarcity of natural resources has incentivized the implementation of more effective waste management practices. Businesses have also incorporated broader system analysis to understand the link between resource consumption and market opportunities for their products.
3. Technological change: The rapid invention and adoption of new technology across consumer goods and manufacturing is outpacing the rate of reuse infrastructure. As a result, more and more new products are ending up in landfill.
4. Climate change and pollution: Solid waste is a significant contributor to greenhouse gas (GHG) emissions. Over 5,000 chemicals are produced in volumes of over 1 million tons per year, which lead to drinking water contamination and other associated public health issues around the globe.

Solid Waste-Management Practices

Some waste management practices are more costly than others, and integrated approaches facilitate the identification and selection of low-cost solutions. Some waste management activities cannot bear any charges; some will always be net expenses, while others may produce an income. An integrated system can result in a range of practices that complement each other in this regard. This means that the integrated solid waste management hierarchy cannot be followed strictly since, in particular situations, the cost of a prescribed activity may exceed the benefits, when all financial, social, and environmental considerations are taken into account. The MSW practices can be divided into four main activities:

1. Sorting and collection: Waste sorting is the process of separating MSW into different types. Waste sorting can occur before or after the waste is collected. The collection process involves collecting waste from households, from community and street bins,or from bulk generators in large containers or vehicles. It extends to activities such as driving between stops, idling, loading, and on-vehicle compaction of waste.
2. Recycling: After waste sorting, recyclables are reprocessed into products.
3. Transfer and transportation: This process involves the delivery of collected waste to transfer stations or treatment facilities.
4. Treatment and disposal: Waste treatment is the process of disposing of waste after collection. Waste can be buried at landfills or burned through an incineration process. Non-recyclable waste items can be converted into compost or energy as various forms of usable heat, electricity, or fuel.

Strategies in Solid Waste Management

Waste management follows a widely recognized hierarchy, developed and promulgated by the U.S. Environmental Protection Agency (EPA) as well as other organizations such as the World Bank. In these frameworks, the preferred solution is source reduction: solutions that eliminate waste creation. When the creation of waste cannot be avoided, recycling or composting is the next best strategy, followed by energy recovery. Disposal is the least preferred option for waste management, as it precludes reincorporating materials into another stream.

1. Sell: As natural resources become scarcer and demand for commodities increases, corporations have found buyers that are transforming their waste into new revenue streams. Waste products can also be converted into new raw materials or inputs for other manufacturing processes.
2. Eliminate: By applying circular economy principles, companies can streamline processes and minimize the volume of raw materials used, resulting in profit-maximizing opportunities.
3. Prepare: It is vital that companies remain proactive, rather than reactionary, regarding waste management and the circular economy. Companies should continuously strive to transform waste products and processes into improvements in their bottom line.

Conclusion

A circular economy is essential because the current waste management system will not support the rising supply of solid waste. Price for recovered materials, contamination from other waste streams, and energy costs all limit how much waste can be recycled or recovered. Rising global incomes and consumer spending will increase overall levels of solid waste and will lead to increases in solid waste that require higher levels of processing, which in turn generates more waste.

Solid waste is a growing issue that is getting increasing attention from consumers and policymakers alike. Barriers to transition from waste management to a circular economy include the lack of a clear starting point, a potential lack of ideas, or nonexistent executive support; all of these barriers have potential solutions. Waste accounting should be addressed from the demographic point of view as well, since high-income regions have a more comprehensive account compared to low-income regions. Embracing a sustainability journey toward the circular economy can start from an understanding of waste and the best way to manage it.

Source: https://onlinelibrary.wiley.com/doi/10.1002/tie.21968

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