Making money out of waste: the compost made in Paris and the pioneers behind it

Les Alchimistes collects bio-waste in the French capital with reduced carbon emissions and social inclusion. The waste is turned into compost, to be sold to urban agriculture and gardening. Relying on investments from a variety of institutions, including the city of Paris, it has Foundation Cartier as its first double client: paying for waste collection and buying the fertiliser. 

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Collecting and composting bio-waste within cities’ limits with reduced carbon emissions and social inclusion. Food scraps become soil, nature, money. That’s the alchemy crafted by Les Alchimistes, the first company to treat waste inside Paris.

The French start-up plans to collect organic waste from restaurants, supermarkets, schools and companies and compost within 3 km from where it was produced. By doing that, Les Alchimistes will drastically reduce waste mileage and collecting costs. Less km means less Co2, especially since the alchemists will collect waste by bicycles or electric vans. Au revoir, smelly garbage trucks!

“There are two movements we are interested in: the circular economy, which is how can we create resources from waste, and urban agriculture, which is to re-grow nature in cities. In order to make nature grow in cities, we need soil. So we are really in the connection between both movements”

tells Alexandre Guilluy, co-founder of Les Alchimistes.


Alexandre, one of the founders, collecting bio-waste riding an electric bike with their partner La Tricyclerie, in Nantes

In France, regulation obliges institutions and businesses that generate more than 10 tons of bio-waste per year to sort and recover the waste, through composting or energy generation. Les Alchimistes proposes to those organisations the waste collection service and will make a compost from it, which will also be sold. In short, the start-up expects to make revenues on both ends.

To do its alchemy, the start-up relies on electromechanical composters and on the bacteria naturally present in food scraps. Les Alchimistes plans to sell the natural fertiliser produced by those machines to local urban agricultures and gardeners.

“We have been concreting cities for decades and today we realize that we need nature to come back to cities. Our compost will facilitate this nature’s comeback”

says Alexandre.


Mathieu, the business developer, ensuring the quality of Les Alchimistes’ compost

So it will be the first commercial compost “made in Paris” and will be consumed…in Paris. We can also expect a compost “made in Lille, Bordeaux or Nantes”, as the start-up wants to conquer la France, according to its business developer, Mathieu Therial.

The trick is that unlike community composters that only process vegetable scraps and eggshells, the machine is able to treat meat and dairy products in a closed system, avoiding undesirable smells and animals. So not only does it fit well with dense cities, but it also delivers a nutrient-richer natural fertiliser. Not to mention that the electromechanical composter consumes little energy and requires relatively little space.

Let the alchemy begin

The experiment idealised by Alexandre and his partner Fabien-Kenzo Sato has just started. Les Alchimistes’ first machine was installed this Summer at the Grands Voisins, a temporary occupation at the heart of Paris connecting hundreds of socially vulnerable people, startups and associations from the solidarity economy and sustainable development sector.

The composter machine, made in England, has the capacity to treat 200 kg of waste per day. Every 90 minutes, a propeller turns slowly, pushing forward the scraps and aerating the system. The oxygen is needed to keep alive the bacteria responsible for the composting. About 12 days later, the food waste becomes a fresh compost. More five weeks of maturation outside, and the compost is ready for use.

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The first composter was installed at Les Grands Voisins, at the heart of Paris

For this first test, Les Alchimistes counts on investments and loans from a variety of institutions, including the City of Paris and Région Île-de-France. The start-up estimates that 150 to 200 machines with capacity to treat 2 tons per day each would be needed in order to compost all bio-waste produced in Paris. “But if we get to have 15 to 20 waste treatment sites in Paris we would be already very happy”, reveals Alexandre. He evaluates that it could happen within 6 or 7 years.

Riding bicycles, the alchemists have already begun collecting bio-waste. One of their first clients is the Foundation Cartier for the contemporary art, which also plans to buy

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Foundation Cartier, client for waste collection and Les Alchimistes‘ compost

their compost to boost its gardens. For that, the start-up will need to succeed in an upcoming test: to prove to French authorities that its compost is good and safe enough, following sanitary rules. So far, the machine seems to work well and deliver a proper fertiliser.

By the end of September, Les Alchimistes will try to get the certification required to sell the compost in France. If everything goes well, we may find soon their product on the shelves of Biocoop, a French network of organic and fair trade shops, which is already a client of their waste collection service.

Eyes and minds

Besides economic and environmental benefits, collecting and composting in the city raises awareness on the waste issue. Today trash is collected, put into a truck and sent far away. Once out of sight, most citizens forget about the problem and their responsibility.

“Recreating the proximity with waste mobilizes citizens on its management. When we treat waste in cities, people stop, ask questions and realize that is possible to make valuable things from it”

believes Alexandre.

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Kenzo, one of the founders, explains how the machine works and raises awareness on waste management

Aware of the potential of many resources that currently end up being burned our buried, more people may start to sort correctly the waste they produce. Les Alchemists’ co-founder recalls that if we put the waste into the right bin at the beginning, later it is easier. But if we put everything mixed, it’s super complicated to value the material afterwards.

“Composting close to citizens, in visible and visitable places is important. We want that people and young students can come, see, understand the waste issue and change their behaviours”, expects Alexandre.

Social inclusion

Les Alchemists aims to work with people from social reinsertion programs. Not only they want to create job opportunities for those who don’t have many, but they will also train their employees as to provide them with more skills and a larger scope. In partnership with the social non-profits Halage and Études et Chantiers, also its co-founders, the start-up will train workers to deal with clients during the waste collection and to operate the composters.

“We will create added value jobs, similar to a super neighborhood caretaker (concierge de quartier). Instead of simply pick up the garbage in a bin and put it into a truck, the employee will be in contact with the restaurateurs, people from the primary schools and green spaces. And he will remain in the neighbourhood, close to the citizens”, explains Alexandre

Composting used baby diapers

The start-up’s next frontier will be to compost used baby diapers in its machines. In order to recover this waste, Les Alchimistes will lead a two-year research and development project in association with CNRS (French National Center for Scientific Research), other research centers and the industry.

“Today baby diapers, which are 80% composed by water and urine, are burnt. And burn water is not very smart”

recalls the founder of Les Alchimistes.

After separating the plastic, used baby diapers are composed of cotton, excrements, urine and absorbent polymers. All that improves plant’s growth and, according to Alexandre, the absorbent polymers – with a high capacity to retain water – could be very useful, especially in deserts, regions with little water or in roofs. Now the question to be answered through this research is wether compost from diapers is safe for the environment.

About 3,5 billion of used baby diapers are thrown away every year only in France, being burned or buried. Imagine worldwide. Thus a solution to recover this challenging waste will help us to pave the way towards a more sustainable society.

As a hit from Jorge Ben Jor, a famous Brazilian singer, goes: “os alquimistas estão chegando”, which means that the alchemists are coming. Hope they will stay for long.

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