Floating rubbish bins are being used by the City of Melbourne to stop litter washing into the Yarra River at Docklands.

Five Seabins were installed at Yarra’s Edge Marina in December, following a successful trial in early 2019.

“Unfortunately an estimated 1.4 billion pieces of rubbish flow into Port Phillip Bay from the Yarra and Maribyrnong rivers each year,” Lord Mayor Sally Capp said in a statement.

The Seabins were created in 2014 by Pete Ceglinski and Andrew Turton, who are Australian boat builders and surfers.

“The plastic in our waterways is everybody’s problem, and so everybody has a responsibility to be part of the solution,” Mr Ceglinski told Government News.

The City of Melbourne decided to install the bins after approaching the Seabin team for a trial.

“The mariners at Yarra’s Edge have a lot of pollution that comes into it from upstream, gets captured and it’s quite hard to get out,” Mr Ceglinski said.

“After the first six weeks, they got like three, four hundred kilos of plastic out of the water and they’re like ‘this is amazing, we’re gonna put it through the system’.”

“The plastic in our waterways is everybody’s problem, and so everybody has a responsibility to be part of the solution.”

The Seabin is the size of a domestic rubbish bin and works like a pool skimmer. The surface of the water is skimmed and then gets pumped out the bottom via a submersible water pump.

In the middle, a filter is used to capture bigger items such as 2L Coke bottles, 4L oil cans, micoplastics, oil and plastic fibres.

Mr Ceglinski says a single units collects about four kilos of rubbish a day, with 600,000 litres of water getting pumped through.

“From this, it doesn’t seem like a lot, but over the period of a year, it’s about one and a half tonnes that each unit on average collects,” he said.

Fish occasionally get caught in the Seabins as there is no way to ensure that only litter gets filtered through.

However, Mr Ceglinski says the amount of fish that gets captured is minimal because the Seabins only skim the surface of the water and fish rarely stay on the surface. Captured fish are later released back into the ocean.

“The probability is less than one per cent by volume, so if you get 100 kilos of pollution, then less than one per cent of that will be bycatch,” he says.

“So, every now and then we do collect some bait fish. Generally, at the end of a period of a week, there might be like two or three or four, less than the size of your little finger.”

To ensure that units don’t float away, they are tied to floating docks in the mariners.

“The mariner staff come around, and they’ll do a visual inspection,” Mr Ceglinski says.

“And if it’s full, they’ll turn it off, empty the filter, put it back in, and it just keeps going.”

The Seabins are emptied twice a day and data is manually collected by Seabin staff or volunteers.

The Seabin team is working to build sensors into the units to measure pH levels and water temperature. They also hope to eventually achieve higher levels of automationn via   optic measurement systems.