Rum production produces rather nasty wastewater which needs to be disposed of some how. The Serrallés Rum Distillery in Ponce, Puerto Rico produces DonQ, its main brand of rum, which is the most popular rum in Puerto Rico. It is one of the largest rum distilleries in the Caribbean with an annual output capacity of 15 million proof gallons. The company has spent a decade and $16 million on a new filtration system.

Serrallés used to dump its wastewater into nearby fields, but during rainy season the waste would run off and the distillery would have to shut down when flooding starting which cost the company $200,000 a year. A Fast Company article claims that Serrallés has turned the “$75 million distillery into one of the cleanest in the world.”