The Buriganga River is the main waterway that provides environmental resources, shipping, and transportation for the city of Dhaka, Bangladesh. Dhaka is home to more than 10 million people who rely on the river for drinking water and economic properties. Today, more than 20,000 tons of tannery waste, including toxic materials are released into the river each day. Additionally, 60,000 cubic meters of toxic waste including textile chemicals and pharmaceuticals are released into the river, along with sewage from the city (80% of which is untreated). This waste comes from industrial areas outside of the city with no sewage treatment plants of their own. The sewage seeps much further than the limits of Dhaka due to high soil permeability.
While the city of Dhaka once shared a peaceful relationship with the Buriganga River, their interactions today are harsh and sudden. A form that was perpendicular to the land resembles the current relationship. By placing the tower on the banks of the river, it sits at a place of confluence and junction. At this place, the natural and human projections bend up the vertical element, reflecting how the two elements must work together to live symbiotically. The result is a human construction that is fused with nature.
The tower is designed around a water filtering system that filters the river and produces electricity, crude oil from algae bioreactors, and drinking water for the population. Through a system that feeds off the energy of the moving river and the toxic material in the water, wastewater is pumped through the entire building, feeding algae and regenerating power like a small hydroelectric dam. The dynamic skin acts as shading and a water collector, and the structural elements eventually carry clean water out into the city. By morphing out of the built fabric, the forms express the people’s reality by rising vertically and latching onto the existing infrastructure.
The first stage of the system is an initial filter that is sunk into the river on the bank. Water flow is controlled with gates that adapt to changing water levels. There are two primary stages at this level, but of which are crude sedimentation basins designed to rid the water of large-scale impurities and trash. Passing through agitators allows the water to receive two basic cleanings before it ever enters the tower. On the far side of the basins turbines stick out into the river, collecting electricity to fuel the pumping.
Once the wastewater reaches the top of the tower and begins to move down with gravity, it will enter fuel cells that clean and purify the water, as well as produce CO2 and bio-waste. The CO2 is then used to feed algae bioreactors in the form of tubes, while the waste is processed in another tube. Algae, when fed proper amounts of sunlight and CO2, can produce crude green oil for use in industrial application. This oil can be used to offset the energy costs of the filtering utilities.
The final stage gains return on the energy spent pushing the water to the top story. Acting like a micro-dam, hydroelectric generators and turbines use the embodied energy in the form of pressure to create electricity that powers the building and puts energy back into the grid. These hydroelectric systems then redirect the water out into the city or back into the river. Some of the water will never reach the hydroelectric system, and instead goes through complete filtration processes to be distributed on site for drinking and bathing. The folding elements of the facade carry clean water far into the interior of the city.
