The Great Bubble Barrier

(A cartoon representation of the Great Bubble Barrier. Source: The Great Bubble Barrier)

As mentioned in a previous post, between 1.15 and 2.41 million tonnes of plastic enters the oceans per year via rivers. Although, a novel method which was thought up three years ago and is getting more and more traction, could drastically reduce this number in the coming years. It has minimal impact on aquatic life and shipping as it just pumps bubbles from the river bed up to the surface creating a curtain which catches the plastic on its way downstream. It is positioned diagonally so that the river current pushes the debris to the bank's where it can be easily collected. Below is a video of the Bubble Barrier in action.

The team estimate that 70-80% of plastic floating on the surface will be collected and 50% of plastic underwater. Although heavier plastics that roll along the river bed are expected to bypass the barrier.

(An aerial image of the Bubble Barrier. Source: The Great Bubble Barrier)

The pilot Bubble Barrier was undertaken in the IJssel river (the fastest flowing river in the Netherlands) back in November and the results will be released to the press next month. It will hopefully show how accurate these above estimates are and exactly which types of plastic are caught or not caught.

Whilst this method will be good for collecting macroplastics (over 5mm in size), microplastics under 3mm will not be caught by the system, highlighting the need for another approach to best deal with this. Although collecting these sub 3mm microplastics, as anyone can imagine, is a tough task with sufficiently innovative technology seemingly lacking.

However,
- How effective will it be during times of high river flow in storm conditions?
- What exactly is the impact on shipping? and,
- Will it affect the natural flow of organic material, leading to a deficient down stream environment?

Well I got in touch with Francis Zoet, CTO of the Great Bubble Barrier, who shed some light on these questions.

She told me that the effectiveness of the barrier could be reduced during times of high river flow and that the barrier is designed for optimal use at average discharge levels.

In terms of shipping disruption, it has been observed that the manoeuvrability of boats in lochs where air curtains are used to prevent the mixing of salt and fresh water, is slightly affected. So Francis identifies the need for more in depth research if barriers were to be put near bridges or lochs. She also suggests the need for more research into the nutrient distribution element of these barriers as the barrier allows past organic material on the river bed but it is bound to get caught up in the collection if it's flowing on the surface or in the main water column

Other than the element of disruption to nutrient flow being perhaps one of the major drawbacks of this project, this seems like an incredibly good solution to the plastic problem and hopefully they reach their crowdfunding target of €100,000 to launch a fully operational Bubble Barrier!

Keep up to date with their progress through their website.