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In exceptional circumstances, water companies in the U.K. are permitted to discharge raw sewage into bodies of water, but data shows excessive releases.

News of excessive sewage spills comes as government plans overhaul of system

Wastewater treatment facilities in the United Kingdom are facing pressure after recently revealed data showed an average of 1,000 sewage spills per day were detected there in 2021. Data from England and Wales has shown that sewage systems released raw sewage into the environment 372,533 times last year, with an aggregated spill duration of more than 2.6 million hours.

Although the U.K.’s sewage discharge problem is nothing new, the 2021 figures seem to be a tipping point.

The government is now planning the most extensive overhaul of the U.K. sewer system since the 1990s, calling it “a step change in how water companies tackle the number of discharges of untreated sewage.”

The Challenge of Storm Overflows

The bulk of the problem comes from storm overflows. During heavy and prolonged rainfall, sewage systems have storm overflows which prevent them from being overloaded. Instead of contaminating waterways and damaging ecosystems, however, the sewage can overflow onto streets and properties.

While U.K. water companies are permitted to discharge raw sewage in exceptional circumstances, the government now acknowledges that the 2021 figures show water companies have been using storm overflows more than they should. U.K. environment secretary George Eustice said:

We are the first [U.K.] government to set out our expectation that water companies must take steps to significantly reduce storm overflows. Today, we are setting specific targets to ensure that those storm overflows are used only in exceptional circumstances — delivering on our Environment Act and building on wider work on water quality.

The planned cleanup aims to eliminate the environmental impacts of 3,000 storm overflows (75%) by 2035, and 80% of total discharges by 2050. Between 2020 and 2025, the government plans to spend about $9 billion (7.1 billion pounds) for sewage infrastructure ugrades. Moving forward from 2025, the cost of the overhaul will raise average water bills approximately $15 (12 pounds) anually. Eustice said:

I know that’s an additional cost but obviously it’s a big investment undertaking to deal with this Victorian infrastructure, people want to see our water quality improving and it’s a cost that won’t present itself until after 2025.

While it is clear the investment is warranted, there are cost-effective strategies that could lessen the need to replace all existing infrastructure and reduce the load on centralized plants.

Dealing With Water Infrastructure Needs

How can water companies reinforce wastewater treatment systems to minimize storm-related overflow? Complete replacement of aging infrastructure is often too expensive to be feasible.

One proven technology that can play a part is the membrane aerated biofilm reactor (MABR), which uses simultaneous nitrification-denitrification and passive aeration to increase effluent quality and cut aeration costs.

Fluence provides MABR in several products, including SUBRE, MABR units that are stacked and submerged in existing wastewater treatment plants for a performance and capacity boost.

Systems contemplating upgrades also have the option of adopting a new treatment paradigm altogether. Decentralization, or installing smaller-scale infrastructure at the point of need, adds flexibility and resilience to treatment systems. By employing packaged plants, you can reduce the load on the main centralized plant. Fluence offers Aspiral™ modular MABR wastewater treatment plants to fill this need.

Fluence is a global company active across Europe with years of wastewater experience and a catalog of adaptable packaged solutions. Contact Fluence — our water experts are here to help.

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