Bocas del Toro Research Station

Research Projects


Excavating for an anaerobic tank

Sebastien Tilmans

U.S. Fulbright Scholar
B.E. Civil Engineering, The Cooper Union for the Advancement of Science and Art
Masters Student, Environmental Engineering, Stanford University

Wastewater treatment in Bastimentos: a comprehensive approach to Bocas’ ecological and infrastructure challenges

Tying the rebar cage around the tank’s inside form

I am interested in harnessing wastes as resources to achieve multiple environmental, economic, and social benefits for a community. In Bocas, I am developing decentralized sanitation systems that are appropriate for the islands’ isolated, low-energy conditions. Bocas’ diverse communities and ecosystems depend on each other and on the water around them. Recent development from tourism is an economic boon----yet it threatens to disrupt the harmonies that sustain the region. Untreated wastewater from growing populations poses significant ecological and public health dangers, while the region’s isolation and general lack of water, sewage, and power infrastructure make it difficult or impossible to implement traditional wastewater treatment solutions.

As an alternative, I am building and monitoring low-cost, low-energy anaerobic-aerobic wastewater treatment systems that can be built and maintained using locally available materials. The advantage of anaerobic digestion (decomposition of organic matter in the absence of oxygen) is that it doesn’t require energy-consuming aerators like many aerobic systems, but instead generates energy in the form of biogas. The gas can be used in cooking to help replace fossil-fuel butane, which contributes to greenhouse gas emissions. Combined with a gravity-fed aerobic post-treatment system, anaerobic digestion is very well suited for tropical climates like Bocas’.

Mixing concrete

I built such systems at four houses around a stream in the town of Old Bank, Bastimentos, in a team effort with the Junta Communal de Bastimentos and environmental engineer Eric Nyman. To supplement this “hard” infrastructure, we stabilized and restored the stream with tropical plants to reduce erosion, remove any remaining nutrients from the water, and restore biodiversity inside town. We are monitoring these four systems for their long-term performance, and working to expand this concept throughout the community.

Installing the lid on the Finished Tank

Our long-term objective is to set up a self-sustaining sanitation and watershed conservation network in Bastimentos that will champion the potential benefits of environmental conservation in an island community.

The First Completed Wastewater Treatment System, Before Backfilling

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