'Tampon tests' could be used to track sewage in rivers
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Version 0 of 1. Glow-in-the-dark tampons could be used to show where sewage is seeping into rivers, scientists have suggested. A study has found that tampons absorb even tiny amounts of “brighteners” found in detergents, toothpaste and shampoo and subsequently glow under UV light. A team at the University of Sheffield has shown that “tampon tests” can be used to track down which houses sewage is coming from at river locations where a problem has been identified. David Lerner, a professor of environmental engineering at the University of Sheffield who led the study, said: “Sewage in rivers is very unpleasant, very widespread and very difficult to track down. Our new method may be unconventional, but it’s cheap and it works.” Prof Lerner’s team is focussing on how to pinpoint housing developments in which waste water pipes are incorrectly linked to the water network. Most new housing is built with separate pipes for sewage and other wastewater, such as rainfall in drains, that can be sent directly into rivers. “All you need is for someone to have a cowboy builder and connect their appliances to the wrong drain and you have sewage going into the river,” said Prof Lerner. Defra estimates that around 5% of homes have misconnections that result in sewage being pumped into streams or rivers, rather than being sent to treatment plants, and scientists believe this is a significant contributor to water pollution in Britain. Just 17% of England’s rivers are judged to be in good health, according to Environment Agency figures released last week. The problem is identifying where sewage is coming from as most existing tests are complex and expensive. The latest study, published today in the Water and Environment Journal, reports that when tampons are dipped for just five seconds into diluted detergent (at a concentration 300 times less than expected in a surface water pipe) optical brighteners could be identified immediately and continued to be visible for the next 30 days. Lerner said one of his students identified tampons as the ideal detector because, unlike most cotton products, they are untreated and do not contain optical brighteners. The test was trialled in the field by suspending tampons on rods for three days in sixteen surface water outlets running into streams and rivers in Sheffield. When they were checked under UV light, nine of the tampons glowed, confirming the presence of optical brighteners - and therefore sewage pollution. Working with Yorkshire Water, the team followed the pipe network back from four of the nine polluted outlets they’d identified, dipping a tampon in at each manhole to see where the sewage was entering the system. They were able to successfully isolate the sections of each network where the sewage originated, narrowing down the households which would need to be inspected in more detail. A visual inspection in one area immediately revealed a house where both a sink and soil stack were connected to the wrong waste pipes. Currently, the only way to be sure a house is misconnected is by using a dye test - putting dye down a sink or toilet and seeing where the coloured water appears. “It’s clearly impractical for water companies to do this for all the households they supply, but by working back from where pollution is identified and narrowing it down to a particular section of the network, the final step of identifying the source then becomes feasible,” said Lerner. The team are now running a larger-scale trial aimed at identifying sources of sewage pollution on the Bradford Beck, which runs through central Bradford. |