These days, it's impossible not to be aware of the environmental issues associated with the accumulation of waste. However, it's still difficult to grasp their full extent, as the way our daily waste is processed renders it invisible once it's thrown in our bins. We're facing an exponential growth in the volume of waste. The urgency is particularly acute with plastic, which is now everywhere but has serious environmental consequences.
Recycling is often presented as the solution to this problem. But what is the reality? How is our waste treated? Is recycling a sufficient solution to break energy dependency? Is the dream of the circular economy achievable?
A quick update on where we are and development options such as bioplastics.
The accumulation of waste, an alarming reality
In France, we throw away an average of about 1 kg of waste per person per day, or 354 kg per year. This figure rises to 568 kg per year per inhabitant if we include municipal waste, which comes from the city's economic activities and follows the same collection and treatment process as household waste. Adding in all waste from businesses and industries, we arrive at a total of 13.8 tonnes of waste per year per inhabitant.
According to the CNIID , in France on average 30% of our waste is incinerated, 36% is sent to landfills, 14% goes to composting or methanization (organic waste) and the remaining 20% is revalued through recycling.
Thus, two-thirds of household waste is still buried or burned, which contributes to water, soil, and air pollution and direct greenhouse gas emissions. Landfills alone account for approximately 16% of our country's methane emissions and a significant portion of soil and water pollution.
Although combustion is used to create energy, producing heat and electricity, the incineration of waste generates a considerable amount of CO2, and combustion results in the formation of solid residues, notably clinker, a compound of highly toxic pollutants that no management method currently really allows to prevent from polluting the soil and groundwater.
In the West, household waste production has doubled in 40 years. For plastic alone, it took 30 years, between 1950 and 1980, to produce the first billion tons of plastic. Since then, an additional billion tons of plastic have been produced every three years, and about half of this plastic is intended for single-use items. This exponential increase in waste is challenging countries' capacity to process it. For years, the United States, Canada, and Europe have been exporting thousands of tons of waste daily to China, the Philippines, Malaysia, and Indonesia for recycling. But the processing capacities of these countries are also reaching saturation point: our exported waste often ends up in open-air illegal dumps. To avoid this, Southeast Asian countries are refusing, one by one, to accept waste from the West.
Recycling is now widely accessible, everyone talks about it, and everyone knows about sorting. But once our trash is collected, what happens to our household waste?
Waste recycling, where are we now?
All recyclable household waste follows the same process. It begins with home sorting, then the bins are sent to a sorting center where professionals separate the waste by composition. Once the waste is finely sorted, it can be processed and recycled.
Paper, glass, plastic, and steel are the main categories of recycled waste. But, when it comes to recycling, not all waste is created equal. Indeed, some materials are easier to recycle than others.
Some recycling waste treatment channels are also more developed than others, which allows for better management of our waste.
Recycling paper/cardboard
According to ADEME , paper and cardboard are 92% recycled and recyclable. In 2018 in France, we recycled 68% of paper and cardboard. Paper, cardboard or food packaging are first crushed then mixed in a large tank filled with water to separate the cellulose fibers from the other materials. The resulting slurry is freed from its impurities, plastic, varnish, glue, staples, aluminum, in a sort of sieve. Then the pulp is washed to remove the ink, spread out and dried to be put into reels. These will then be transformed by specialized companies to become books, newspapers, toilet paper, wallpaper, paper napkins, gift wrap, kraft envelopes, or even furniture thanks to the transformation into chipboard panels!
Steel recycling
Steel can be recycled endlessly without altering its properties or losing weight, which makes it a very good candidate for recycling. It is also very well managed by French sectors: 100% of steel is revalued, which represents the equivalent in steel of 1,200 Eiffel Towers! Aluminum recycling is lower, since only 44% is recycled ( CITEO ). Steel and aluminum arrive at recycling centers in the form of cans, tins, aerosol cans, etc. These objects are first crushed then pass through a low-temperature furnace to remove impurities, lacquer, varnish, or labels, then through a high-temperature furnace to melt them at 1600°C. The molten steel or aluminum is then drawn on a table: steel in the form of plates, coils, bars or wires, aluminum in the form of plates or ingots. They will then be processed by specialized companies. The steel will be transformed into tin cans, beverage cans, household appliances, concrete reinforcement, metal structures, and automotive parts. The aluminum will be transformed into tin cans, beverage cans, aluminum foil, trays, aerosol cans, windows, doors, gutters, kitchen utensils, and automotive parts.
Steel recycling brings clear environmental benefits: one tonne of recycled steel saves more than twice its weight in raw material, 70% of its weight in energy, and avoids 57% of the CO2 emissions and 40% of the energy consumption required to produce one tonne of primary steel.
Glass recycling
Glass is also one of the best materials for recycling because it can be reused endlessly. In France, three-quarters of glass packaging is recycled ( ADEME ). But this excludes crystal, mirrors, Pyrex dishes, and even glass tableware, which are mixtures of materials. Recycling therefore always begins with a professional sorting step to remove objects that are not made of pure glass. Mechanical sorting then removes capsules, earthenware and porcelain debris, corks, and paper. Then the glass is crushed and transformed into cullet. The latter is melted in a furnace at a temperature of 1400°C, combined with silica, soda, limestone, and colorants. The molten paste passes into a mold where it is blown into the shape of bottles, jars, or flasks, before cooling.
Plastic recycling
Plastic packaging bearing the recyclable symbol is multiplying, but what's behind this logo? Because plastic is a complex material, there are many different types. Only five types of plastic are recyclable: PVC, polyethylene, polystyrene, PET, and polypropylene. Currently, only PET plastic is 100% recyclable without compromising quality.
Household waste mainly contains polyethylene (PE). There are two types:
- Transparent PE: PET (Polyethylene Terephthalate). It is impact resistant, lightweight, impermeable to water, gases and aromas.
- Opaque PE: HDPE (High Density Polyethylene). It is opaque or translucent, rigid, resistant to shocks, grease and chemicals.
To be recycled, PE bottles are first cleaned with steam to peel off the labels and remove impurities. The bottles and caps are then crushed into flakes. These are then washed to remove the glue. Placed in water, where the two types of plastic can be distinguished: HDPE will float, while PET will sink. The PET flakes are then pressed and dried, and the HDPE flakes are melted and then cut into gray granules. The flakes and granules will then be processed by specialized companies into new bottles, polyester fibers for fabrics, carpets, fleeces, and wadding for stuffing anoraks, duvets, and pillows.
Every year, 5 million tons of plastic are used in France. But when it comes to household packaging, only 26% is recycled.
This rate is still low because plastic is not yet collected everywhere in France and the infrastructure still needs to be modernized to increase the volume managed.
But collection is not the only problem: plastic packaging is often made from mixtures of different types of plastics, and today, we do not yet know how to separate these materials from each other.
For metal, the iron extraction process is extremely polluting because the separation of the ores requires chemicals that are stored in retention basins representing long-term pollution risks.
When it comes to glass, the transportation of silica sand from quarries has the greatest environmental impact. One ton of recycled glass saves over 500 kg of CO2. Glass is an excellent material for recycling because it doesn't degrade and is very well managed by the recycling sector in France.
It is urgent to reduce the pressure of human activities on the ecosystems from which we draw most of our materials to preserve our drinking water supply and air quality. Recycling is an essential solution to achieve this because it saves the natural resources needed to produce our everyday objects: oil for plastic, wood for paper, iron for steel and aluminum, and silica sand for our glass objects.
For example, one ton of recycled plastic avoids the use of 800 kg of crude oil. Similarly, recycling paper and cardboard prevents the felling of tens of thousands of trees each year. Producing an A4 sheet of paper consumes an average of 5 liters of water.
This is an essential saving when we know that 90% of global energy consumption is based on non-renewable resources and that it is urgent to reduce our dependence on fossil fuels.
It also helps to limit global warming by reducing pollution caused by incineration and landfilling of waste.
However, recycling as it is carried out today does not allow us to take care of all our recyclable waste, which takes us further away from the ideal of the circular economy.
The limits of recycling
Despite significant progress, most of what could be recycled still isn't. There are several factors that explain this.
First, waste management costs. These have exploded in recent years, while the price of oil has rarely been so low. Manufacturing new materials therefore appears much cheaper than developing the recycling sector.
Added to this are the many sorting errors that remain, whether intentional or unintentional. Recycling instructions are sometimes complex and vary by region, and therefore remain poorly understood by many households.
On the other hand, a large proportion of materials degrade during recycling, until they become completely unusable. They are then no longer recyclable and are sent to incineration or landfill. Only glass and metal can truly fit into a circular economy concept because they can be recycled endlessly.
However, even for glass and metal, this remains nuanced. A recycled aluminum object can rarely retain the same use. For example, an aluminum can will rarely give rise to other aluminum cans because the process alters the quality of the material and the manufacture of cans requires the use of very pure metals. Ultimately, aluminum, supposedly one of the most easily recyclable materials, can only be integrated here in an open loop, that is, mixed with other materials following its recycling to form less demanding parts.
Packaging is evolving. New materials are entering the market, including biodegradable plastics.
What about bioplastics?
The term bioplastic covers bio-sourced plastics derived from wheat, corn, beets, sugarcane, and potatoes. The most common are bioPE (polyethylene), bioPET (polyethylene terephthalate), and PLA (polylactide). Biodegradable plastics are also used, as they are supposed to degrade into elements such as carbon, hydrogen, and oxygen when placed in industrial composting.
Bioplastics currently only represent 1% of the mass of plastic produced, but they are generating a lot of buzz.
They would represent an ecological solution to the problem of pollution because they come from renewable natural resources.
But this poses a problem in itself: growing food for bioplastic production. If bioplastic production increases, food crops and plastic crops will compete.
While bioplastic cultivation is certainly renewable, it doesn't have all the advantages. These crops involve the use of pesticides and fertilizers , even GMOs, and are also extremely water-intensive. According to the Plastic Atlas, to produce one ton of PLA, 2.39 tons of corn are needed, which requires 0.37 hectares of land and 2,921 m3 of water.
Ultimately, the overall environmental impact of bioplastics is no better than that of their petroleum-based counterparts. While they may have a lower carbon footprint, their overall ecological impact is greater.
Bioplastics are often credited with the advantage of being biodegradable, but among the bioplastics produced today, less than half (44%) are actually biodegradable due to the chemical transformations they have undergone.
When bioplastics are actually compostable, industrial conditions are required. Therefore, waste should never be disposed of in nature, where it will never degrade.
To be destroyed, bioplastic must be heated to 60°C for several weeks to produce usable compost. Composting and recycling of biodegradable bioplastics is still marginal because collection channels are less developed than those for conventional plastics and it is expensive to develop them. This waste is therefore often incinerated.
Bioplastics can be interesting for diversifying raw materials, limiting dependence on oil (by using renewable materials) and allowing natural “recycling” if they are biodegradable.
But bioplastic isn't a miracle solution. Throughout its life cycle, it generates environmental impacts just as harmful as its conventional counterpart. It's important to remember that using disposable products consumes resources and energy for their production and transportation, even when they're made from bioplastics and compostable.
Furthermore, bioplastic carries the risk of a perverse effect: by continually presenting it as ecological and safe for the environment, bioplastic could well generate a rebound effect and slow down our efforts to reduce our plastic production. Because this is the main strategy to adopt.
We must first strive to use as little plastic as possible, even "organic" plastic; to ban single-use plastic even if these disposable items are biodegradable. Only then can we resort to bioplastics, preferably not derived from food crops.
Bioplastics, like plastics and other waste, urgently need to be reduced. To do this, we can apply the three Rs pyramid: reduce, reuse, recycle. Reduce: by finding substitutes (metal straws, wooden cutlery). Reuse: stop single-use and extend the lifespan of our objects. Recycle: recycling must become a systematic reflex. Even if habits gradually change, we still have a lot of room for improvement: the plastic recycling rate in Western countries is estimated at between 25 and 30%, and the world's plastic recycling rate would not exceed 10% according to the World Bank in 2019.