Floating underwater filter captures plastic pollution in rivers

Edit Hook
The Floating Coconet is a design that aims to collect and direct free flowing plastic pollution in rivers before it has a chance to reach the ocean. It uses rows of fins inspired by the manta ray and basking shark to collect small pieces of plastic.  The design is set up in a modular way, and the team is aiming to deploy multiple “Coco-Trees” on the river bed, lined up in a specific pattern to optimise their functionality. The Coconet has a rigid shell  to protect it from the underside of passing boats. These shells will be made from recycled plastic. The Coconets are linked together with a rope, which makes it possible to rotate the Coconets in order to replace the filled-up nets.

Challenges Solved

The plastic pollution in our ocean has unprecedented effects on our world. It is said that all sea creatures, from the largest to the microscopic organisms are, at one point or another, ingesting plastic or swallowing sea water containing toxic chemicals from plastic decomposition. Many organisms mistake coloured plastics for food. Eating these plastics gives them a sense of being full, when in fact they aren’t. Along with the organisms living inside our oceans consuming and being harmed by what we are leaving behind, plastics take years to break down and decompose, becoming micro-plastics. This decomposition release greenhouse gases, which contribute to climate change. Scientists fear that chemicals in plastics and also chemicals which attach themselves to plastic in the natural environment could cause poisoning, infertility and genetic disruption in marine life, and potentially in humans if ingested in high quantities.

Biomimicry Story

Floating Coconet looked at manta rays and the basking shark. Manta rays are considered to be a filter feeding species. The fins on the front of its body enable the manta ray to funnel the water containing food particles into the mouth. Unlike other filter-feeding organisms, manta rays have modified gill-rakers to filter the food from the water. As expelled water flows though the gill-rakers, it forms into swirling eddies that causes food particles to ricochet off the lobes back into the mouth. This strategy has two different advantages: First, repelling the particles instead of trapping them, meaning that the system is resistant to clogging. Secondly, it enables the manta ray to capture prey that is smaller than the gaps in the gill-rakers. Similarly, The basking shark filter feeds by having a beak lined with tiny bristle-like hairs. When swimming, water will pass through these bristles. Due to the shape of the bristle, the water will become turbulent and the little food particles/plankton will fall in between these bristles. The water then exits the gills and the food is left behind. This inspired the gills in our design and the modified gill rakers to collect micro-plastics as well.
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