Les Alchimistes



Web: alchimistes.co
Contact: contact@alchimistes.co
Location: L’Ile-Saint-Denis (93)
Sector: End of Life
Date of creation: December 2016
Date of analysis : June 2020
Maturity of project: Perennial

A solution for the local recovery of bio-waste from companies and communities.


Created in 2016, Les Alchimistes is a company that collects and composts urban bio-waste. Historically, the idea of the project was to develop a collection and composting chain for baby diapers. However, this project is still in the experimentation phase – see the dedicated section for more information – and the company has therefore mainly reoriented towards composting bio-waste. Indeed, bio-waste represents a third of the French population’s residual garbage [1]; it is therefore a significant source that must now be diverted from disposal. The Alchemists have therefore put in place a relevant and innovative solution: reorganizing the treatment of bio-waste in urban areas and short circuits in order to achieve a circular economy of organic matter.

Their first composting site was launched in the summer of 2017 in Les Grands Voisins, a former hospital in the heart of Paris transformed into a cultural space hosting associations, craftsmen and young companies. At the time, they had a composting capacity of 30 tons per year… compared with nearly 800 tons in the Paris Region today! Indeed, the Alchemists now have about twenty employees on 3 sites in the Paris Region, and about thirty people are part of their network. The project is currently being developed in other cities (Toulouse, Toulon, Marseille and Reunion Island) as a franchise for Les Alchimistes. In addition, Les Détritivores in Lyon merged in January 2020 with Les Alchimistes to become Les Alchimistes Lyon.

In addition, the project also has a strong social dimension, with the employment of people in integration. Les Alchimistes have thus obtained ESUS (Entreprise Solidaire d’Utilité Sociale) approval, which allows them to be recognized as a social and solidarity enterprise (ESS) and to obtain aid and funding.

  • 700 T of bio-waste composted on one site / year
  • 150-200 T of compost generated / year
  • established in 6 cities
  • short circuit collection: 15 km radius
  • Recycling

As a reminder, ADEME defines recycling as “any recovery operation by which waste, including organic waste, is reprocessed into substances, materials or products for their original function or for other purposes”. 2] The Alchemists are part of this recycling process by using bio-waste from professionals in cities to make compost.
What is compost?
Compost is a natural fertilizer formed from organic waste. Once mature, it can be mixed into the soil and is an excellent fertilizer that promotes plant growth. It can also be used as mulch directly on the soil to nourish and protect plants.
The Alchemists produce compost under anaerobic (oxygen-free) conditions. Unlike conventional composters in aerobic (with oxygen) conditions, they are microorganisms that decompose organic matter through exothermic (heat-generating) reactions.
Their process can recover up to 700 T of bio-waste – fruit, eggshell vegetables and even fish and meat remains – per year and per site. Most often in France, this waste is incinerated (or buried). The Alchemists’ process thus makes it possible to recover them while limiting the carbon dioxide emissions linked to the life management of “classic” waste (transport to sorting centers at least 70 km from Paris, then landfill or incineration). This approach is part of the Grenelle 2 law which aims to eradicate the incineration of bio-waste by 2025. For more information on bio-waste and compost, Zero Waste France has created a site dedicated to informing citizens and professionals. This site explains very clearly why and how to recycle biowaste, and presents an observatory of initiatives in France and abroad.

  • Sustainable Supply

Les Alchimistes’ compost, produced from urban bio-waste, is a local product and labeled “Made in Paris” and NFU 44 051 standard, rich in organic matter and nutrients.
Their compost is then distributed in the city according to the needs of each person: bulk purchase by weight, by bag or in “big bags”. The Alchemists are thus responding to a strong demand from urban development projects, urban agriculture or shared gardens that do not have access to quality compost in sufficient quantity and proximity.

project operation

The Alchemists are currently located on the LIL’Ô site on Ile-Saint-Denis (93).
This site, which is currently being rehabilitated, is a former backfill storage area whose soils had become completely infertile.
The company shares the 3.6-hectare site with the association Halage, which specializes in integration via landscape trades. On the LIL’Ô site, the association has set up projects to restore the soil and biodiversity as well as flower cultivation. In particular, they plan to provide flowers for all the bouquets for the 2024 Olympic Games in Paris. The association Halage has also signed a contract with the Alchemists, which provides them with compost for 1 year in order to amend the soils.
The Alchemists have installed their first electromechanical composter with a composting capacity of 700 T per year.


The LIL’Ô site, where the Alchemistes and the association Halage work

The Alchemists have for vocation to develop only in short circuit. Thus, the bio-waste collected comes from company restaurants, restaurants, florists, school canteens and supermarkets less than 15 km from the composting site.

a. The collect
The Alchemists thus recover bio-waste from their customers using “soft” transport: small trucks, bicycles and even on horseback.
The employees of Les Alchimistes exchange full bins for empty bins, which are washed by Les Alchimistes (this service is very much appreciated because customers do not have to wash their bins). Each bin is scanned and weighed, which allows a detailed follow-up of the quantity and quality of waste for each customer.

Bio-waste collection bins

b. The sorting

The bin is then dumped on a sorting table, where a visual check is made to ensure that the compost contains only organic materials (fruits, vegetables, fish, large bones, coffee and tea, eggs, leftover meat plates) and no plastic, glass, metal, food packaging, paper towels or cardboard. Guests are rated according to the quality of the compost, and this rating will increase or decrease the price to be paid by the biowaste producer. It is an incentive pricing system that makes customers aware of food waste and the quality of sorting. It is based on three criteria:

  • actual weight of the bin (the lighter the bin, the less food waste, the less customers pay)
  • quality of the sorting (the more the sorting is respected, the less customers pay)
  • fixed price for bin collection

Sorting machine of the bio-waste

c. Pretreatment
Wood shredded from unused Rungis pallets is then added to the compost. The shavings provide carbon to balance the nitrogenous material, absorb moisture and structure the material to make it less compact. The material is then crushed and pressed to extract the excess juice from the mixture, which is sent for methanization.
The mix thus formed feeds the electromechanical composter little by little: about 2 tons are added every day.

Bio-waste shredding and pressing machine

d. Electromechanical Composter
The electromechanical composter at the LIL’Ô site, produced by Tidy Planet, has a composting capacity of 700 T / year. It allows to optimize the composting process in aerobic (presence of oxygen) by thermophilic bacteria (the compost reaches temperatures between 70 and 80°C). Oxygen is injected continuously, and an auger allows mixing the compost in order to oxygenate it uniformly. This semi-enclosed system avoids odour nuisances thanks to a bio-filter, and the intrusion of rats or insects.
As the compost contains animal foodstuffs, strict measures are followed to verify that pathogenic bacteria do not develop (e.coli…). This hygienization is done by maintaining the compost at a temperature of at least 70°C for 1 hour and then testing batches of compost.
The bio-waste remains on average between 1 and 2 weeks in the compost bin. Every 30 minutes, a conveyor belt transfers the material from the electromechanical composter to the compost maturation areas.

An electromechanical composter

Screen for the supervision of the electromechanical composter

e. Processing and maturation stage

The compost matures between 4 and 5 weeks in the open air; instead of 6 months to 1 year with conventional composting. Then, the compost is screened to separate the wood shavings and obtain a fine compost (2 different calibers according to the recipients of 10 and 20 mm). The compost is then conditioned and sold to individuals and professionals. 

Maturation of compost in the open air

The Alchemists’ initial objective was to find channels for ultimate waste (non-recoverable waste that is nowadays either buried or incinerated). They thus launched into the development of a collection and composting system for baby diapers. In France alone, 3.5 billion baby diapers are thrown away every year and no recovery has yet taken place!
This project is still being tested because of strict regulatory and sanitary restrictions that limit the possibility of composting human excrement on a large scale. The Alchemists are working in particular with ADEME and the City of Paris to provide proof that the composting process they have set up does not present any health or environmental risks.

sustainable approach

The short circuit model set up by the Alchemists provides a significant environmental gain: it limits the transport of bio-waste outside cities. The soft logistics used during the bin exchange tours also helps to reduce transport-related CO2 emissions.
Composting has several environmental virtues, including :

  • the recovery of organic waste that would be incinerated or landfilled
  • improvement of soil quality (nutrient and structural)
  • the increase of biodiversity in the soils (this favours the presence of decomposer fauna and flora)
  • substitution of chemical fertilizers

In France, since January 1, 2012, people who produce or hold a significant quantity of biowaste are required to sort this biowaste and have it recovered in appropriate channels (such as composting or methanation). 3] Since January 1, 2016, professionals producing more than 10 tons per year of biowaste, and 60 liters per year for oils, are concerned. Les Alchimistes has therefore entered the market of waste collection and management service providers and offers them a competitively priced solution (the service is around 250-300 €/T).

As for the sale of compost by the Alchemists, its use has undeniable economic benefits: it avoids the purchase of chemical inputs. However, the compost is sold at a much higher price (x10) than the market price (see Reproducibility section). This high price can be explained in particular by the fact that it is a rare product in the city and of much higher quality than conventional compost produced from green waste and not from food waste.
Les Alchimistes’ solution allows integrated management of bio-waste for professionals, with complete and integrated management of the life cycle of its transformation. Les Alchimistes, it is also a close and long term relationship with the consumers of compost.

Les Alchimistes is above all a company with a social and societal purpose. Thanks to its ESUS status (social utility solidarity enterprise), it can employ people from social integration and help them regain a taste for work and financial and moral stability, by accompanying them in their personal journey. The employees are satisfied with their rewarding work because they follow the entire composting cycle, from waste to compost.
The Alchemists also aim to promote local compost in the city. They create visible and visitable sites to raise awareness among the general public and elected officials about the challenges of organic waste management in urban areas.

Replicability & future developments

The company has been very successful, as evidenced by the fact that franchises are beginning to develop in several major cities in France. Many of their customers have come to them to benefit from their services. Indeed, professionals are obliged to sort their waste and entrust them to approved service providers. Les Alchimistes have therefore entered the market of waste collection and management service providers at a competitive price (the service is around 300 €/T).
Compost is sold at around 250-300 €/T on average for professionals (about 10 times the market price for traditional compost). Compost is sold at around 3€ per kg (also around 10 times the market price).
Sale of compost in bags for individuals


The double-entry model set up by the Alchimistes Ile-de-France enables the company to be economically viable and to employ 12 people, including 8 compost collectors, employees from the integration program.

Thus, the Alchemists have the will to set up in cities where there are strong constraints (neighborhood, lack of space) that do not allow the installation of methanizers or conventional industrial composting platforms. Indeed, their installations do not require a lot of space, do not present any olfactory or sound nuisance, and do not attract rodents and insects thanks to their closed system.
For large cities, it is possible to set up several modular composters at different locations in the city, to reduce the travel distances between customers and the composting site as much as possible.

One of the obstacles to their installation is the agreement of the cities, which can sometimes be long to set up.

Other similar companies offer organic waste collection and management in cities, such as Moulinot. These are their most head-on competitors. However, while the Alchimistes compost 99% of the bio-waste collected (the rest is non-compostable waste), Moulinot offers different types of recovery (compost, vermicompost, energy and fertilizers).

On the LIL’Ô site, there are still a lot of improvements to be made, including ponds for making shoreline plants and flowers, as well as a training center for urban agriculture.
Halage is also developing its activity to be able to supply the 2024 Olympic Games in Paris with flowers.
In addition to the development of franchises in several major cities in France, the Alchemists will open two new sites in the Paris region:

  • 1 site in Chilly Mazarin (91) which will be a test area for composting in the electromechanical composter but with forced aeration directly during the compost maturation stage.
  • 1 site in Stains (93) where the compost will be made from the bio-waste of the households of a whole district via a voluntary contribution.

The Alchemists aim to develop 10 composting sites in Ile-de-France within 2-3 years, and more than 1,000 sites in France within 30 years.

We really enjoyed visiting this composting site, which is different from conventional industrial composting. The micro units of industrial composting proposed by the Alchemists are more adaptable, more modular and more responsible alternatives.
They would be particularly adapted to cities that do not yet have a conventional composting center.
The energy transition law for green growth now requires communities to offer all inhabitants a solution for sorting bio-waste at source, and the Alchemists could be an answer to this need!

Copyright CirculAgronomie 2020