Study Finds Sewage Discharge by UK Water Companies the Top Polluter of UK Rivers

A new study by scientists at Oxford University has shown the extent of the sewage discharge problem in the UK.

The research paper titled 'The combined effects of treated sewage discharge and land use on rivers' found that sewage released by UK water companies was more damaging to the rivers than agricultural waste.

This comes at a time when the world including the UK is gearing up to celebrate World Rivers Day on September 24.

The study published in the journals of Global Change Biology and Ecological Solutions and Evidence highlights how sewage discharge is affecting UK rivers, especially the decline in water quality and its impact on plants and animals dependent on it. The effect can also be felt on the surrounding lands along the polluted waters.

Although UK rivers are critical in the global water cycle, biodiversity and human health, the UK water companies are allowed to pollute the rivers with treated and untreated wastewater, especially during heavy rains. These polluted waters are a health risk if used for drinking, agriculture or other human activities.

The team of UK researchers at Oxford analysed three sources of polluted waters - treated sewage discharge, agriculture and urban run-off. Four rivers in England were tested for three months at different times of the year. Both upstream and downstream flow of sewage was analysed.

The results of the study revealed that treated sewage discharge had more nutrients and algal bloom. They also contained more sewage fungus than agricultural waste and urban run-offs.

Call for better wastewater plant regulation to prevent sewage discharge

Speaking about the matter, Dr Dania Albini from the Oxford University team of UK researchers said: that the sewage discharge study calls for the urgent need for action to address the issue.

Dr Albini called for more stringent regulations for wastewater plants to safeguard the integrity of UK rivers and ensure the safety of the ecosystems and humans.

Another author of the study Dr Michelle Jackson said that the study dispels the debate regarding the impact of sewage discharge on rivers. The results from the study clearly showed the strong influence of sewage discharge on the river ecosystem.

Dr Jackson called for better conservation and management of the UK rivers based on the data available from the study.

A key indicator of polluted waters is the presence of algae like cyanobacteria which are known to produce toxic chemicals harmful to aquatic organisms. The study found an abundance of cyanobacteria in areas of treated sewage discharge. This could degrade the ecosystem, making way for the loss of species, explained Dr Jackson.

Dr Jackson further elaborated on how the presence of insect groups like stoneflies, mayflies etc. in areas of agricultural waste is a cause of concern. Although the problem is severe in treated sewage discharge areas, agricultural pollution should also be controlled, said Dr Jackson.

This comes at a time when a recent report by The Observer found 90 per cent of UK freshwater habitats to be polluted by raw sewage, agricultural waste or water abstraction.

Early detection of sewage fungus to reduce the sewage discharge problem

The UK researchers investigating the sewage discharge problem in the country also created a new method of analysis of polluted water. Scientists have devised a method for early detection of sewage function in water.

Sewage fungus is a complex mixture of harmful aquatic microbes – fungus, algae and bacteria which is an indicator of deteriorating water quality. This large mass of microbial outgrowth happens when the nutrient levels in water are high as in sewage discharged water.

It's a smelly unpleasant mass of microbial growth which is usually detected visually once they have grown to a larger extent and reduced the oxygen levels of water, killing fishes and other aquatic animals.

Through machine learning and cutting-edge imaging techniques sewage fungus particles were detected in water. According to the scientists, this will help reduce their spread and protect UK rivers.

Dr Michelle Jackson termed the new method of sewage fungus particle detection "a canary in the coal mine" as it can be used by both environmental agencies and UK water companies to limit water pollution.