Coffee grounds are not only left over in our coffee machines, they are also produced in enormous quantities in the production of soluble coffee. Now researchers are working to recycle these residues. In this way, cellulose for paper production could be obtained from the coffee grounds. Chemical base materials for bioplastics, chemical additives or oils can also be produced from coffee grounds.
Coffee is one of the most popular beverages worldwide, and correspondingly large amounts of coffee grounds are produced – an estimate of around six million tons a year. These remnants not only come from coffee machines and private households, but are also produced in the production of soluble coffee variants and beverages containing coffee. For example, producing one kilogram of instant coffee produces two kilograms of wet coffee grounds.
Oil and chemicals from coffee bean residues
So far, the coffee grounds have mostly ended up in waste – although the powdery substance still contains many valuable ingredients. In fact, there are already initial approaches to use the coffee grounds, for example, as a fertilizer, as an additive in animal feed or even as an absorber material for gases. Researchers around Inna Bretz from Fraunhofer UMSICHT are currently working on the extraction of valuable raw materials from the coffee grounds in the project “InKa – Intermediate from industrial coffee grounds”. The aim is to find methods with which the coffee grounds can be converted into high-quality chemical raw materials for bio-based products and for industrial processes. For this, the coffee grounds are broken down into different parts step by step.
It starts with the extraction of the oils contained in the coffee grounds. The coffee oil is not suitable for consumption, but it can be converted into a valuable chemical intermediate. To do this, the oil is first chemically modified by reaction with alcohol and separated from the rest of the material. Further chemical processing can then be used to obtain various chemicals from this substance that can be used as basic building blocks for bio-based plastic additives, but also as raw materials for other chemical processes. In their project, the researchers want to develop and optimize appropriate processes for this. “The desired process as a whole is highly innovative and makes an important contribution to the use of bio-based raw materials in the context of the bioeconomy,” explains Bretz. “We develop the technical process from the laboratory to industrial scale-up.”
Can also be used in papermaking
Valuable raw materials can also be obtained from the de-oiled coffee grounds. “The de-oiled coffee can be a good raw material supplement for special types of paper and cardboard,” explains Jürgen Belle from BellePapier GmbH, who as project partner will carry out the application tests of the intermediate products developed by the researchers. “The coffee grounds contain cellulose – similar to the pulp from which paper is made.” Therefore, de-oiled coffee grounds could be used as an additive to the pulps used in paper and cardboard manufacture after they have been comminuted. “The coffee grounds could also be interesting as a process aid. We are very curious about what other uses this material could offer, ”said Belle.
Source: Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT