Every year, around 18 billion pounds of plastic enter the world’s oceans. Much of this plastic is carried out to sea from the interiors of continents by river currents. As can be seen in the map accompanying River Plastics Emissions to the World’s Oceans, a paper published in Nature last year, few of the worlds coastlines are free of this phenomenon. Asia, with its high population density, historical trend of importing plastic waste from the west for reuse, and high concentration of rivers, is a hotspot for river transport of plastics to the oceans.
The movement of plastics through rivers is bad for the local environment, but it has one major advantage – the rivers concentrate the plastics into a single stream. This fact has inspired entrepreneurs to try to come up with an effective way to capture the plastics concentrated in river flows.
Entrepreneurs Step up to the Challenge
Anne Marieke Eveleens, a Dutch amateur sailor-turned-entrepreneur, was inspired to solve the problem of plastic entering the North Sea from the many rivers that reach the sea in The Netherlands. Now one of the major innovators in the field, she has recently begun development of a novel application of a technology typically used in the oil and construction industries – the bubble barrier.
Bubble barriers consist of a thick screen of bubbles rising from the riverbed in a line extending across the entire river. The bubbles are created by forcing pressurized air through a pipe laid across the bed of the river or lake. As the bubbles come out, they entrain solid materials or viscous materials such as oils. Today, they are primarily used for two purposes: reducing the effects of shock waves associated with underwater blasting and construction and stopping the spread of oil spills. These applications typically involve still water, not flowing water.
A New Use for an Old Tool
Eveleens hopes to use the barriers for a different purpose. The plan is to create a bubble barrier that extends diagonally across the river’s current. As plastic waste becomes entrained in the rising bubbles, the river current will push the plastics along the diagonal barrier to one side of the river, where the waste can be collected and recycled or disposed of.
The idea, called “The Great Bubble Barrier”, seems to hold promise. In 2016, Eveleens and her team won a Dutch government plastics waste management competition. As a prize, the government provided funding for a pilot project, which was conducted over the course of a month on the river Ijssel.
The results were promising – the bubble barrier could remove many plastic objects ranging in size from 1 mm to 1 metre. Perhaps in the coming decades bubble barriers will become widespread on the world’s major rivers.