In a house at the top of a hill, a nanosensor is dropped into a toilet bowl. The device’s mission is to flow through the sewer along a predetermined perimeter and, while passing by Bluetooth spots previously installed, register all the information it comes across: the size of the pipes, the drainage volume, the locations likely to clog. Then comes a team of specialists, composed of designers and architects, who cross this data with a map of the terrain, created with the help of lasers, and create a 3D digital model of the entire structure. The goal is to find ways to prevent flooding and reuse water.

It sounds like science fiction, but this initiative has already been implemented in the Vidigal community, in Rio de Janeiro, and should soon migrate to the capital of São Paulo. The project’s author is Pedro Henrique de Cristo, 34, with a Master’s in public policy from Harvard, whose dissertation inspired a course in the world’s most prestigious university. “Mauro Quintanilla [a community leader from Vidigal] and I are working to green São Paulo’s downtown, redrawing and transforming public space with a focus on integration and sustainability,” explains De Cristo.

A man smiles at the camera and shows the palms of his hands stained black. He has white skin, short, wavy blond hair, is wearing a white t-shirt and has a watch with a black rubber wristband on his left wrist. In the back are the unfinished structures of walls and a ceiling, covered by roof tiles, and a few more men spread out.

Pedro Henrique De Cristo, creator of the system to map the sewers using nanotechnology (De Cristo’s Personal Archive)

A partnership is already in place with the National Nanotechnology Laboratory at Universidade Estadual de Campinas (Unicamp) to implement a solution in São Paulo  this year. The project is also being conducted in Brooklyn, New York, and in other cities around the world, a cosmopolitan synergy of ideas on sustainable urban alternatives. “It’s cheaper to do this kind of technology here than in the United States, on the same scale and for the same number of people,” claims De Cristo. The total cost to produce the system in Brazil is 300,000 reais ($114, 000 USD), a fraction of the cost of developing the system on U.S. soil, where the cost can be close to 1.5 million dollars.

On the upper left corner, the title "How Technology Works to Map the Sewers," in uppercase, and the subtitle "The challenge is to know the underground terrain, in order to uncover possible clogging and to reuse water," are written in black. Below is a drawing of a lawn, with underground tubes connecting 4 pink circles, containing the following words, respectively: "1. The surface is mapped by a laser beam that generates an accurate 3D drawing."; "2. A sensor is launched by the toilet to cover the sewage and send data to the Bluetooth located at defined sites of network maintenance."; "3. The sensor passes through the Bluetooth, sending information about the circumference of the pipe and the distance travelled."; "4. The device follows the route and passes through the other Bluetooth points completing the network mapping." On the lower right corner of the illustration are the following credits: Source: Pedro Henrique de Cristo/Design com propósito - 2017.; Artwork: Marina Lang/Believe.Earth.

The mapping done by the sensors and Bluetooth points shows the specialists how the sewer waters can be reused. In the case of clogs during storms, it is also possible to see the blockage locations in the pipes. “You can know exactly where the issues are and fix these problematic spots,” says De Cristo.

A four-part grid has the following text, starting from the upper left square and ending in the lower left square: "Errors in the collected data are corrected on the computer by architects and designers"; "A 3D digital geometrical model is built"; "The flow of water is simulated in the 3D model of the pipes: it's possible to see the path the water takes"; "From there it is possible to predict blockage during storms, manage water reuse, and understand the dynamics of flooding. There are many possible uses for this technology." On the lower right corner of the illustration are the following credits: Source: Pedro Henrique de Cristo/Design com propósito - 2017.; Artwork: Marina Lang/Believe.Earth.

RJ-SP AXIS
The biggest challenge, both for Rio de Janeiro and São Paulo, is that, with climate change, the concentration of rainfall in short periods has led to erosion. With gradual rainfall, there is little damage to the soil and reservoir levels go up. But when too much rain falls at once, the soil suffers, becomes sandy, erodes, and causes problems like flooding and landslides. “We started to deal with erosion in Vidigal, which didn’t use to happen. Of course, human action also contributes, but we had floods that would drag away cars,” recalls De Cristo.

The biggest problem with the floods in São Paulo is the lack of adequate urban planning – over 200 rivers cross the city, and the majority of them were paved over for the construction of avenues and buildings. One heavy rain is enough to overflow the creeks. On the other hand, although it seems contradictory, Brazil’s largest city has also suffered from a lack of water. “The Rio-SP axis is the largest macroregion on the planet, with 45 million residents. These cities create a mass of hot air, of high pressure,” explains De Cristo. “When the rain comes, the humidity bumps against this mass and it rains somewhere where it’s not supposed to rain.”

There is another experiment conducted in Vidigal that will be implemented in the city of São Paulo: a system to capture, treat, and redistribute rain water, like one that in use in a square in Vidigal’s ecological park. “Almost 100% of the rain goes into an organic, natural filtering system that purifies the water and redistributes it to the community and the park,” says De Cristo.

All of these initiatives are part of what Pedro calls “essentialism” a trend that defends urban integration through social democratic action and sustainability.