Waste Bacteria Help Coffee Farmers Purify Water

A new technology funded in part by the Dutch government uses bacteria from animal waste to purify the wastewater from coffee processing, which is highly acidic and poses a severe threat to the environment.

The $20,000 anaerobic biodigester "works by transferring wastewater from the [coffee] pulping process into a collection tank. A mesh gauze filters out the largest pieces of solid waste," according to The Guardian.

Technical expert Leonardo Sánchez, director of Costa Rican environmental consultancy Aceres, explained how the process works.

“The collection tank is where hydrolysis begins, resulting in the initial decomposition of complex organic and inorganic substances,” he said, per the report.

Next, the wastewater moves to the central biodigester. There is a layer of animal waste in this compartment. Bacteria from the waste "decompose any remaining organic matter," according to the report.

Sánchez explained that the bacteria function by feeding "on the contamination found in the coffee wastewater which they eat and [transforming] into a product they then excrete. Through this process of transformation, the bacteria takes the energy it needs to live, move and multiply,” he said, per the report.

After 12 hours, the treated effluent makes its way into another tank, and then into lagoons.

“We are just entering our second harvest using the biodigester, but in the first year our calculations show that the system reduced the levels of contamination by 81.3%”, said Marvin Mairena, the coffee farm's agronomist.

Wastewater from coffee processing poses a threat to the environment.

It "has a really high content of organic matter and acidity,” said Vera Espindola of UTZ, a Dutch certification entity that participated in the project. “When it’s discharged directly into waterways, it can kill aquatic plants and wildlife by depriving them of essential oxygen.”

According to a Catholic Relief Services blog, "The wastewater from the [coffee] wet milling process is one of the leading contaminants of local water sources in coffee-growing communities."

UTZ is taking a lead role in addressing the effects of coffee waste.

UTZ Certified's project, "which began back in 2010, aims to address environmental and health problems caused by the wastewater produced in the coffee industry. The Energy from Coffee Wastewater project has proven that is possible to generate energy, tackle climate change and protect water resources by treating discharges from coffee mills," according to PFSK.