School of Engineering


UKZN and The Ocean Cleanup Partner to Tackle Umgeni River Plastic Pollution

UKZN has teamed up with The Ocean Cleanup – a Dutch non-profit organisation that is developing advanced technologies to rid the oceans of plastic – to investigate the mechanisms of plastic pollution in the Umgeni River and its transportation through all seasons.

The project will span three years (2021 to 2024), mapping plastic pollution hotspots and fluxes in the river and along the Indian Ocean coastline.

‘This is a project about mapping, trapping, collecting, processing, testing, modelling and engaging,’ said South African Research Chair (SARChI) for Waste and Climate Change, Professor Cristina Trois, who is the Lead Investigator on the project along with colleague, Dr Thomas Mani from The Ocean Cleanup.

‘How many plastic items have you used today already? Are you possibly using one just now? The answers are very likely “many” and “yes”,’ said Mani.

Trois said that this was not surprising considering plastic’s roaring success across global markets starting in the 1950s. Today, more than 400 million tons of plastic products are purchased every year worldwide.

Trois said that, while these materials have brought many benefits to the modern world – for example in sterile medicine, lightweight automotive and aviation – at the end of their use, plastics pose a vast environmental problem. ‘Of the total of over eight billion tons of plastics produced to date, a staggering 80% have already ended up in landfills or the environment. Once lost, plastics will fragment into smaller pieces – microplastics (<5 mm) – and pose a threat to ingesting organisms.’

Rivers are believed to be major pathways for plastic waste on land to reach the oceans. A new global modelling study indicates that 0.8 – 2.7 million tons of plastics are transported towards the oceans each year, with small urban rivers among the most polluted. According to this study, five major streams in the Durban area alone may carry as much as 1 340 tons towards the Indian Ocean. Among these is the beautiful but plastic infested Umgeni River (an estimated 380 tons per year).

Mani said that the anthropogenic and environmental mechanics which drive this riverine plastic transport are still largely a mystery. ‘For this reason, empirical physical evidence is needed to support the current model data. When and how do plastics spill into the Umgeni? How fast and how far will they be flushed downstream? How much and when will the plastics reach the river mouth and the Indian Ocean? What happens after these drink bottles, shopping bags and lunch-boxes reach the ocean?’

These are some of the main questions that Trois, her team of researchers and Mani, Lead River Field Scientist in the research department at The Ocean Cleanup seek to answer.

‘Driven by the belief that one needs to understand a problem to be able to truly solve it, The Ocean Cleanup pursues a strong research emphasis in line with its mission to rid the world’s oceans of plastic by deploying mechanical clean-up devices in the offshore ocean as well as in rivers,’ said Mani.

With the use of satellite imagery, airplanes and drones, river cameras, floating GPS trackers, “litter-boom” waste characterisation, underwater sampling and beach litter characterisation, this research partnership seeks new insights into the seasonal dynamics of plastic waste transport through the Umgeni River system and aims to provide a replicable model for cities in the West Indian Ocean (WIO) region.

To kick-off this exciting research voyage, a workshop was held for stakeholders including UKZN, The Ocean Cleanup, the National Department of Science and Innovation (DSI) through the Research Development and Innovation (RDI) Waste Roadmap, eThekwini Municipality, The Bateleurs, Durban Green Corridors, and Sustainable Seas Trust (SEAS).

A team from The Ocean Cleanup including Mani joined UKZN researchers for the initial mapping flight over the Umgeni River catchment on 27 May with a light airplane provided by The Bateleurs, a non-profit group of volunteer pilots who avail their aircraft for conservation causes.

Words: Sally Frost

Photograph: Supplied