BioBrew uses vermifiltration—a low‑cost, bio‑based method where earthworms and microbes clean coffee wastewater and turn pulp into nutrient‑rich fertiliser. The two-stage system works as follows:
Compost Tank: Wastewater enters a gravel-and-organic media tank. Worms digest solids, producing compost and partially clarified water.
Circulation Tank: This water is sprayed over a worm‑sawdust filter. Worms and microbes remove remaining pollutants and balance pH. A solar‑powered pump circulates the flow, and the treated water is safe for irrigation or discharge.

Key Features:
Scalable & Modular: Fits farms of any size (e.g., 500 L + 1 500 L tanks).
Local, Low‑Cost Materials: Built with PVC, gravel, and organic fibres.
Open‑Source DIY: Farmers assemble and maintain the system.
Solar‑Powered: Cuts energy costs and emissions.

Field tests in Cauca, Colombia, showed major drops in organic pollutants, improved water quality, and high‑quality compost production. Iterative tweaks have made BioBrew robust in real‑world conditions.