Lombriz Nadando is an affordable and straightforward coffee wastewater filtration system based on vermifiltration, which utilises earthworms in an aerobic treatment process. Specifically designed for small coffee farms, it effectively minimises the environmental impact.

Why Coffee Pollution?

Coffee pollution is an underrated problem within the coffee industry and occurs during the washing process at coffee plantations. And the most two important factors is water consumption and contamination.

Some wet-milling processes use up to 1200 litres of water or more for each hundred-weight bag of coffee cherry, which may produce as little as 8 kg of export-ready green coffee.
The wastewater or honey water is one of the leading contaminants in local water sources as it lowers pH levels and creates an anaerobic environment to kill life. The mucilage is loaded with sugars and pectin which will be fermented into acetic acid when released into local waterways. In addition, coffee cascara, or pulp, accounts for 2/3 of the weight of the whole coffee cherry. The most common way to treat the pulp is compost. However, some farms also discard it directly near the field, but it contains caffeine and alkaloid-rich leachate which is bad for the soil.
Technology & Maintenance Lack of maintenance is the most common issue with the existing solution, the SMTA system. This may result in an over flow, blockage and a low removal rate. The lack of knowledge and feedback from the system provider may also result in frustration among coffee producers
Economic Most farms in Cauca don’t use any water treatment due to the cost compared their farm size and production. Moreover, electricity and water supplies are unstable.

Coffee cherry washing and sorting, Finca Patio Bonito

La Alejandria and the abandoned water treatment system, Caldono, Cauca

The fresh coffee cascara, Finca Patio Bonito

Interview with Rodelfi Betancurt, El Mirador, Caldono, Cauca

Interview

Design for small coffee farms

In Colombia, Cauca Department, famous for specialty washed coffee, 99.4% coffee farms can be considerate as small farm, they worked individually, and most producers own roughly only one hectare of coffee.

What is vermifiltration?

Vermifiltration is a biological treatment process during which earthworms and microorganisms reduce the organic compounds inside the waste water.

A series of experiments were conducted to validate the worm dynamics and tolerance to honey water and cascara. In addition, a comparison experiment showed that vermifiltration was superior in digesting and purifying water as compared to that without worms, demonstrating a rise in pH, a decrease in °Brix, as well as a better ability to transmit water.

Prototype in Colombia

Prototyping

The prototype in Pescador, Colombia

The very first vermifiltration system for coffee waste was build at Finca Patio Bonito, Pescador, Cauca, Colombia. This system is a practice for Lombriz Nadando to test in an actual context by sourcing the majority of materials locally and validating the design by using honey water and compost fresh coffee cascara.

The prototype was built on the hillside next to the washing space so it can use the gravity to let the waste water to run through the pipe and filter tanks and finally the water can be absorb by soil tank or be used for irrigation. There are still some problems to be solved in the future, such as monitoring the load rate over a long period of time and finding the optimal variety of earthworms.

This is a system can compost the coffee cascara and purify the coffee fermentation wastewater at the same time. Using the solar panel to power the spray system. Due to its modular design, the system can be expanded in the future.

The small scale prototype in London studio

Green Concept Award Nominee 2024

Learn more

Thanks to

Paola Trujillo and her family, Finca Patio Bonito, Coffee Producer in Cauca, Colombia

Prof. Michael Templeton, Civil and Environmental Engineering, Imperial College

Dr Laure Sioné, Civil and Environmental Engineering, Imperial College

Elsa Germain, Civil and Environmental Engineering, Imperial College

Nestor Campo, Member of CAFICAUCA, Colombia

Lucia Solis, Coffee processing expert

CATA Export, Green coffee export / dealer

Jon Townsend, AST & Adviser

And

Alma Castro, Finca La Sierra, Cajibío, Cauca / Olga Lopez, La Alejandria, Caldono, Cauca / Hugo Trujillo, Las Orquídeas, Caldono, Cauca / Rodelfi Betancurt, El Mirador, Caldono, Cauca / Camila & Blanca Trujillo, Finca La Colina, Caldono, Cauca / Merly Joyas, Los Pinos, El Tambo, Cauca / Richard Velasco, El Porvenir, El Tambo, Cauca