A sustainable sewage treatment plant for Isabela

Isabela is one of the four inhabited islands in Galapagos and is home to the town of Puerto Villamil. With around 3,500 permanent residents and over 80,000 tourists visiting the island each year, solutions to the increasing strains on the town’s sewage system are crucial to ensuring a thriving ecosystem. One major issue threatening both local inhabitants and wildlife was the leaching of bacteria, metals, plastics, pesticides and sludge into the surrounding ecosystems as there was no treatment system in place. In order to tackle this, in 2016 WWF contracted an expert to design a low-cost and low-maintenance solution for the municipality of Puerto Villamil, which included updating an existing naval tank with a new filtration system to reduce environmental contamination. The project involved Caduceus, Orcatec, the Isabela Municipality, the National Bank of Ecuador, the Galapagos Consejo de Gobierno and the Galapagos National Park.

The refurnished naval tank now serves as a septic tank, which separates out sewage water from the sludge, as well as other solid components such as plastics, sand and gravel. The separated sewage water is then passed into five newly created wetlands, providing vital nutrients for several endemic and native species of plants. These species, as well as many other plant species, are crucial for wildlife in the area, including birds, insects and reptiles. One of the plants that was planted is Xanthosoma sagittifolium, known locally as the ‘otoy’ plant, which the Galapagos National Park wanted to be planted in order to feed the giant tortoise population at the local breeding centre.

Additional achievements include: 

• the retrofitting of a 182 m³ sewage tank with a modern filtration system, which can treat the sewage water of up to 1,500 people a day. 
• the creation of 6,000 m² area of wetland on the adjacent land to the tank into which the treated water is released. 
• Treated sewage water compliance with local environmental standards for discharge into the surrounding environment. 

The new system also has benefits for local residents, as the treated water can be used for everyday tasks such as gardening, cleaning cars and general municipal tasks. Additionally, reusing sewage water reduces the strains placed on freshwater sources on the island by local residents. The entire system also requires very little maintenance, with the wetlands needing just one hour of maintenance a day, and the treatment system needs checking just once a week. This treatment plant is the biggest of its type in Ecuador and the plan is to implement this sort of design throughout the entire island of Isabela and other islands in Galapagos. Going forward the municipality of Santa Cruz is seeking to recreate a similar design for sewage water treatment in the highlands of Bella Vista. The project has been a perfect example of how we can learn from nature to apply natural, low-cost and highly effective systems that can benefit local wildlife and people.