August 3, 2017

Green Coffee: How Wet Processing Is Becoming More Eco-Friendly


Just like any other industry, coffee production has an environmental cost. With wet processing, it comes in the form of water pollution and waste byproducts – things that can ruin the local ecology, farmland, and in some places, even the drinking water.

Fortunately, the industry is also working towards becoming more sustainable at every level. I reached out to Alvaro Gaitán, Director of Cenicafé, Colombia’s National Research Centre, and Dr. Carlos Oliveros, Leader of Post-Harvest Strategies at Cenicafé. They agreed to speak to me about the different ways wet/washed processing can be more eco-friendly.

Spanish Version: Café Verde: ¿Puede el Beneficio Húmedo ser Eco-amigable?

coffee beans

Washed coffee beans dry on a raised bed. 

Why Focus on Washed Processing?

There are many ways to get coffee seeds, or beans, out of the coffee cherries. Yet out of all the main processing methods, washed/wet uses the most water.

However, it’s also one of the most popular methods. It results in a clean, consistent cup. For coffee producers, it offers reliability. And while natural and honey coffees can be just as good, they need a lot more quality control.

And even though the industry is becoming more open-minded about alternative processing methods, washed still does the best in competitions and awards.

Improvements here could make a significant difference to the coffee industry’s environmental footprint.

coffee beans

Coffee beans being washed.  

Water Pollution: One of Coffee’s Worst Side-Effects

From depulping to fermenting, traditional methods of washed processing use water at every phase. According to Cenicafé research from 2015, it takes 40 litres of water to process just one kilo of parchment coffee like this.

What’s more, Carlos tells me that water contamination is a major issue. The sugars from the coffee cherries end up in the water and ferment, becoming acetic acid. And where does this acidic wastewater go? In many cases, straight back into the local waterways.

Through something called self-purification, waterways can handle small levels of pollution. But there’s a limit to this, and pollution from coffee mills tends to exceed it. According to the Specialty Coffee Association of America (SCAA) in 2013, “the pollution load in the wastewater from the wet milling of coffee can be 30 to 40 times greater than the one found in urban sewage”.

In fact, the International Coffee Organisation (ICO) go so far as to say that “one of the main problems for some regions is water pollution arising from wet processing”.

coffee beans

Dry coffee beans.

Reducing & Purifying Wastewater

Carlos tells me that there are ways to both reduce water use and purify polluted water, especially with the right equipment. The first step is to reduce the amount of water used. For example, Cenicafé has developed demucilagers that use as little as 0.3 litres per kilo of parchment coffee.

Alvaro also highlights the ability to purify polluted water. He tells me they developed an anaerobic treatment (Sistema Modular de Tratamiento Anaerobio/SMTA) that uses plant-based biofilters and can be applied after fermentation.

In addition, Carlos recommends reusing the wastewater instead of releasing it back into the waterways. He tells me that byproducts, such as the mucilage and exocarp of the coffee cherry, can be composted for use as a biofertiliser. In Cenicafé’s Belcosub (beneficio ecológico de manejo de subproductos), the wastewater can be added to the pulp for composting.

coffee cherries

Harvested coffee cherries ready for processing.

Using Byproducts

It’s not just the wastewater that can be reused. Only a small amount of the coffee cherry is consumed as coffee: the rest is often just discarded. However, it doesn’t have to be. Carlos tells me that reusing byproducts not only reduces the environmental impact but can also create opportunities.

The main byproducts from producing and processing coffee are the layers of coffee cherry, defective beans, and wood from stumped trees (something that is done to encourage new, better growth). The pulp alone, according to Cenicafé, represents 2.25 tonnes per hectare every year in Colombia.

So how can these byproducts be reused? Well, we’ve already looked at biofertilisers. Other options include biofuel and biomass for energy.

We’ve also seen a growing market for consumer products made with byproducts: coffee flour, coffee cups, and – the most well-known – cascara tea. As the Mintel report 2017 Foodservice Trends states, “Consumers are concerned about food waste and chefs are finding new ways to repurpose ingredients to reduce overall waste. One beverage that fits into this trend is the coffee/tea hybrid cascara, a beverage created by the discarded skin of coffee cherries.”

These types of products can offer consumers a new way to experience coffee and provide producers with additional income, on top of helping to make coffee a more eco-friendly industry.

“In the future,” Carlos tells me, “there may be new products that can evolve into new industrial opportunities.”

coffee waste

Biofertiliser made with coffee waste. Credit: Karla Quiñones

SEE ALSO:  Honey vs Natural Micro-Lot Coffee: 3 Ways to Avoid Water Pollution

A Greener Coffee Industry

Sometimes, it can be hard to find the motivation to invest in sustainability. The impact seems invisible. Yet small changes can have large impacts.

Carlos tells me that, in Colombia, these measures represent a saving of 20 million cubic metres of water annually. If that’s hard to picture, he says it’s comparable to the amount of water consumed every year by Pereira, a city of 474,356 inhabitants.

Alvaro adds that we shouldn’t feel we can neglect water conservation just because we live in places with easy access to it. He tells me that, in Colombia, it’s rainier than many other producing countries. This can lead us to think of water as an unlimited resource – but water pollution, he argues, still impacts Colombians.

“We need to be responsible with our water use,” he says. “Moreover, the coffee-producing areas in Colombia are the main areas through which water passes through before reaching the cities.”

coffee beans

Green coffee beans ready for roasting.

Coffee’s environmental impact cannot be overlooked. Water must be treated as a precious resource, and the value in reusing byproducts must be acknowledged. Fortunately, through technology, equipment, and entrepreneurialism, it’s possible to create a much more sustainable coffee industry.

All interviews conducted in Spanish and translated into English by the author.

Please note: Café de Colombia is a sponsor of Perfect Daily Grind.

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