How a favela in Rio got its clean water back, for $42,300

RIO DE JANEIRO — Butterflies and waxbills fly through the enchanted valley just outside the Tijuca Forest National Park in Rio de Janeiro. There are fruit trees, a nearby waterfall and impressive views over the Atlantic Ocean. But for decades, something has spoiled the idyll: the stench of raw sewage.

Electricity arrived in the low-income Enchanted Valley community in the late 20th century — which takes its name from a nearby housing project — but the utility never connected it to the city’s sewage network. Waste polluted the local environment and endangered the health of residents.

So the community set out to solve the problem itself by building a biodigester and an artificial wetland to handle all the wastewater generated by all of its 40 families.

It became fully operational in June and is the first independently built biosystem for an entire Brazilian favela, according to Theresa Williamson, executive director at Catalytic Communities, a nonprofit that supports underserved communities. And it could serve as an example for rural hamlets throughout Brazil. According to official data, 45% of Brazilian wastewater is not collected.

The Enchanted Valley project is years in the making. In 2007, the president of the local residents’ association, Otávio Barros, took a group of tourists to a waterfall that was going downhill and when they wanted to bathe in the water, he said they couldn’t; all of the community’s sewage flowed through that waterfall. However, the seed of an idea was planted and he began to rally support.

“It was harder then to raise awareness, show that everyone would benefit,” he told The Associated Press as he walked through the community.

He found allies among researchers at the Pontifical Catholic University of Rio de Janeiro, where he had worked as an administrative assistant. They received funding from the Rio State Foundation to support research to complete a first phase in 2015, and more recently from the German and Brazilian non-profit organizations Viva Con Agua and Instituto Clima e Sociedade to connect each home. , with additional funding from Catalytic Communities.

Barros worked with five other residents in the area for months, including about three weeks during which they just broke through rocks to create a path for new pipes. They lead to the dome-shaped biodigester, where wastewater is taken up by anaerobic micro-organisms. Residual liquids then snake under the landscaped wetland and are cleaned by fertilizing the plants above.

The full price of the system was about 220,000 reais ($42,300). That’s a quarter of what it would have cost to run pipes through the forest to the existing sea-level sewage network, according to Leonardo Adler, co-founder of Taboa Engenharia, which oversaw the engineering side of the works.

The federal government has a plan to improve sewage treatment across Brazil, which it is pursuing through private concessions from major urban areas. But that approach doesn’t help small, isolated communities like Enchanted Valley, where the smell of sewage is now gone and the nearby waterfall is clean to bathe in.

“I’m very happy because it was a very difficult stage to bring in partners, get the community involved to collect the wastewater and clean it back into the environment,” said Barros. “It’s part of a dream coming true. We have others for the Valley.”

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