Macau Matters | River Trash Collection

Richard Whitfield

One of the things I love about the World Wide Web is how you can serendipitously find interesting information and technologies. I especially like finding things that can potentially have application in Macau and its hinterland.

I recently ran across a great article (www.weforum.org/agenda/2019/11/bubble-barrier-amsterdam-canal-plastic-pollution-waste-river-ocean-sea/) about how perforated pipes can be laid diagonally across the beds of rivers and have air pumped through them to create “barriers” of bubbles. Trash floating downstream gets caught in the bubble barrier and is moved to the edge of the river where it can be easily collected. Tests in the Netherlands have shown that this technology can catch around 85% of the trash floating downstream in a river.

Bubble barriers have previously been used to contain oil spills and to reduce underwater noise around seabed construction sites but this is the first time the idea has been adapted to collect waterborne trash. Fish can simply swim through the bubbles and boats can float across them without harm. As well as being a great river trash collector, the bubble barriers also oxygenate the water making it better for fish and discouraging the growth of harmful river algaes. It is also already well known that bubble barriers reduce man made underwater noise to reduce the stress on fish and other marine animals.

It is estimated that each year over 8 million tonnes of plastic and other trash floats down rivers and storm water systems and ends up in the sea where it accumulates in huge mid-ocean gyres causing untold damage to marine ecosystems. Several international cleanup initiatives are now going on to try and resolve this major global problem. Surely, cleaning trash from waterways should be a cost effective way to help solve the problem – prevention is always better than cure!

Now, garbage boats collect and remove about 42 tonnes of rubbish from Amsterdam’s waterways each year. Bubble barriers could be a more cost effective way to do this work. I would be very interested to know how much rubbish is collected from Macau’s beaches and waterways each year – I bet it is a lot. If you spend any time traveling round the waterways in the Pearl River Delta you will see huge amounts of rubbish that ends up in the sea. You will also see great efforts made to beautify the countryside so that it is clearly unacceptable to spoil these efforts with rubbish running rampart.

How about a school competition throughout the Delta where kids go out to identify and document heavily polluted waterways. Universities could then be contracted to develop and experiment with bubble barriers and other methods for collecting rubbish from the worst polluted waterways and document the improvements achieved. In this way we could gradually clean up all the Delta’s waterways and scientifically determine the most cost-effective cleanup approaches, and disseminate this information globally. We could even take it a step further to trace back to where the rubbish first enters the waterways and take action to eliminate these pollution sources. Such a long term project would not be expensive, and would provide substantial practical and educational benefits.