Coffee Wastewater Through the Lens of an Environmental Engineering Graduate

Counter Culture CoffeeBy William Garde

In the winter of 2009, I was in South Africa with a missionary—little did I know the short trip we were about to take would change my career path. Piling into the Land Rover, we soon passed a sign that read “Zimbabwe.” Only ten years had passed since I had visited Zimbabwe, but I did not recognize the city of Bulawayo upon my return. After trudging through the derelict city, we found my father’s childhood home. It was in disrepair and clearly abandoned: the once well-groomed gardens had overtaken the sides of the house.

“Careful, raw sewage runs in those trenches, and cholera is a nasty disease,” my guide warned. This reminded me of a similar situation I had experienced a month prior in a remote village in Tanzania. There, I was instructed not to use any outhouses because occupants regularly fell through the rotten wooden floors and drowned. These experiences lead me to pursue a career in civil and environmental engineering, but I had no idea that they would also lead me into the world of coffee. Every coffee geek has their reason to obsess over freshly-brewed beans—mine was a girl. At the time, I wasn’t interested in coffee; but then I met Allison. She loved to spend time in coffee shops sipping London Fogs, and I desperately scrambled to find some item I could sip alongside her. After my first mocha, I never turned back from coffee (or the girl). Around the same time, I ran into a specialty coffee guru, Chris Bean. Chris worked as a campus minister at the University and introduced me to the ways of the barista. But he didn’t just show me how to pull a great shot and pour latte art, he taught me how coffee and hospitality work in tandem to improve the lives of others. He modeled this by packing up a one-group Spaziale into the back of his minivan, driving to campus, and deploying the portable caffeine dispensary during finals week. This is what specialty coffee meant to Chris: hospitably sharing his craft with others. I was hooked—coffee was a craft beverage that connected me to others.

During my last undergraduate semester, I researched industrial waste. Of course, I had to turn this project into something about my obsession—coffee. I stumbled upon a blog I had never heard of: Catholic Relief Services (CRS) Coffeelands. Michael Sheridan had written a blog post on coffee wastewater, highlighting how little the coffee industry actually knew about this subject. It was at this moment that my two worlds—engineering and coffee—fused into something completely unexpected: I came to the realization that the coffee industry, like all industries, has environmental challenges and a very real environmental impact.

Coffee Management SystemsOnce I became aware of the environmental hazard of untreated coffee wastewater, I found myself constantly wondering how the coffee industry could address this issue. This led to my decision to pursue a master’s degree in environmental engineering—with an ulterior motive to use this knowledge to positively impact coffee. In 2015, I found myself at the SCAA Symposium, thanks to the Fellowship program. Being awarded a Fellowship was a pivotal moment for my career. That Symposium was when water became its own topic, and Paul Hicks presented on the state of pollution from coffee milling and depth of our water ignorance. I left Symposium that year more motivated than ever to pursue treatment research.

Unfortunately, it is a difficult field to study. High quality academic research is difficult enough on its own. Add an exotic waste stream not encountered in the United States and an extremely limited base of peer-reviewed information and you’ve already started out far behind in the research world—not to mention my need for coffee wastewater to experiment with. My creative solutions (coffee from the zoo, shipping cherries from Nicaragua, etc.) didn’t come through, and I realized I’d have to go to the source.

That’s when I heard from Fred Cowell, the general manager of Kauai Coffee. He was interested in the research and wanted to develop research relationships with universities. So with that, I was on a plane to Kauai a few weeks later.

Coffee wastewater is unique: it’s not well characterized, but research does show it is extremely high in organic content. This wreaks havoc when directly discharged into surface water, as microbes suck out oxygen in the water to breakdown the organics, leaving none for larger aquatic life. But it is not all doom and gloom—coffee wastewater can actually be useful too. As my advisor always says, “Pollution is just a resource out of place.”

A popular option for treating coffee wastewater is a biogas reactor. These reactors use microbial activity to digest wastewater
and breakdown the large organic compounds, producing valuable sludge and biogas. The sludge can be potentially used as fertilizer,
and the biogas as fuel for heat and cooking. However, biogas reactors can be costly and complex. However, over the past few years there have been some successes using biogas reactors, and they will almost certainly play a major role in reducing the impact of coffee wastewater.

Another option is constructed wetlands. These are engineered systems that use vegetation, soil, and microbial activity to treat wastewater. They are a popular option for treating highway runoff in the United States as they can be aesthetically pleasing. Recently, they have been adopted to treat coffee wastewater and have had success, but wetlands do have limitations. They require a moderate amount of flat space, considerable time (up to 30 days for treatment), and significant capacity for wastewater.

Joe DriscollMy research focused on using a naturally derived coagulant to remove organic compounds. The coagulant causes the particles floating around in the wastewater to collide and group together, eventually falling out
of the solution and forming a sludge on the bottom of the container. This is very similar to a cloudy swimming pool: after a chemical coagulant is added, the water becomes crystal clear with a small layer of dirt on the bottom that the pool owner can vacuum up. I had some success, but what I discovered is that most of the problem-causing organics were dissolved into the wastewater and could not be removed through coagulation or filtration. Hence, another difficulty in treating coffee wastewater.

Ultimately, it’s going to take additional research to tackle the issue of coffee wastewater. Some basic questions remain unanswered,
such as, how much treatment is enough? Some countries’ standards limit chemical oxygen demand to 200 mg/l—coffee wastewater is roughly 30,000 mg/l. That’s 99% removal! We would be lucky to achieve that in the United States! But in order to begin answering these important questions, as an industry, we’ll need to begin working together: we need farms willing to be research sites, entities willing to fund projects, and universities willing to research this topic. The lack of studies—and access to those studies—is a hindrance to the coffee industry, especially the farmers and producers who deal with coffee wastewater every day.

So, do we have a wastewater problem? Yes. But where there are problems, opportunities for solutions exist. The people that make up the coffee industry are not ones to turn a blind eye to problems, and I am excited what innovative solutions emerge through research for treating and utilizing coffee wastewater.

Garde_WWill lives in Houston, Texas
with his wife Allison. He started his coffee journey in high
school as a barista and poured
 lattes all the way through his
 degree in civil engineering. He
 had the opportunity to pursue
his master’s degree in environmental engineering specializing in hydrology, with a focus on researching coffee processing wastewater and alternative treatment options for his thesis. He would like to continue using his engineering skills to further sustainability and water resource management in the coffee industry.