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Sanitary products contribute to 'river of rubbish'

Sanitary waste makes up over a fifth of waste discovered submerged along the river bed of the upper Thames Estuary according to new research. Thousands of pieces of plastic have been discovered by researchers at Royal Holloway University of London and the Natural History Museum, but more than 20% of waste was made up of sanitary products.

What lurks beneath: sanitary waste collected during river sweepWhat lurks beneath: sanitary waste collected during river sweep

The most contaminated sites were in the vicinity of two Thames Water sewage treatment works – Crossness and Long Reach. The site with the greatest proportion of sanitary products was Erith Rands with 24.24%; Crossness and Littlebrook had 22.69% and 22.76% sanitary products respectively. The most commonly found sanitary items were the backing strips from sanitary towels and used condoms.

A spokesperson for Thames Water said: "The drains connected to homes were not designed to cope with anything other than wastewater, toilet tissue and human waste. Even the products labelled ‘flushable’ do not break down in the sewer, and sanitary products should never be flushed.

"But, quite simply, London has outgrown its Victorian sewer system. The proposed Thames Tideway Tunnel and Lee Tunnel, currently under construction, are essential to capture the tens of millions of tonnes of sewage and whatever else is flushed down the toilet that currently overflows untreated into the tidal River Thames every year.

"This is a big and growing environmental hazard that needs and is getting urgent attention." 

The scientists say that the sheer amount of plastic recovered shows there is an unseen stream of rubbish flowing through London which could be a serious threat to aquatic wildlife. The findings, published online in Marine Pollution Bulletin, highlight the cause for concern, not only for ecosystems around the river but for the North Sea, into which the Thames flows.

Using fyke nets designed to catch Chinese mitten crabs, the scientists documented rubbish collected during a three-month trial. More than 8,000 pieces of plastic were collected, including large numbers of cigarette packaging, food wrappers and cups.

However, speaking to WWTonline, Dave Morritt, a senior lecturer in marine biology at Royal Holloway and co-author of the study, said that larger items like nappies and smaller items like cotton-bud sticks would not have been captured due to the design of the nets, so the real quantity of litter is still unknown.

Dr Morritt said: “The unusual aspect of the study is that these nets are originally designed to trap fish and crabs moving along the river bed, so we can see that the majority of this litter is hidden below the surface. This underwater litter must be taken into account when predicting the amount of pollution entering our rivers and seas, not just those items that we can see at the surface and washed up on shore.”

Morritt told WWTonline that he was “taken aback” by the quantity of litter picked up on such a short section of the Thames and “how much must be rolling up and down the river on a daily basis.”

He said: “The potential impacts this could have for wildlife are far reaching: not only are the species that live in and around the river affected, but also those in seas that rivers feed into. The waste collected for the study is only a small snapshot of the volume of litter which may exist at the bottom of the Thames.”

Paul Clark, a researcher at the Natural History Museum and co-author of the study said: “All of this waste, which was mostly plastic, was hidden underwater so Londoners probably don’t realise that it’s there. Plastic can have a damaging impact on underwater life.

“Large pieces can trap animals but smaller pieces can be in advertently eaten. This litter moves up and down the river bed depending on tides.

“The movement causes the pieces of plastic to break down into smaller fragments. These are small enough to be eaten by even the smallest animals, which are in turn eaten by larger fish and birds.

“Once digested, plastic can release toxic chemicals which are then passed through the food chain. These toxic chemicals, in high doses, could harm the health of wildlife.”

The researchers are surprised at the direction their research has taken and delighted at the media and public interest.

“The feedback has been amazing,” Morritt said. “It has opened many people’s eyes.”

They are now pressing for changes to both policy and consumer behaviours as the dangers of plastics become more apparent.

Reference: David Morritt, Paris Stefanoudis, Dave Pearce, Oliver Crimmen, Paul Clark, "Plastic in the Thames: A river runs through it", Marine Pollution Bulletin, 

Author: Natasha Wiseman, Water & Wastewater Treatment Find on Google+
Topic: Sewer Networks
Tags: sewage , wastewater , River pollution , thames tideway project

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