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What’s the worst thing found in a UK sewer? What problems do we create when we flush pills and cotton buds down the toilet? How does your washing machine harm fish? And what can we do to make our wastewater systems work better for people and planet? Professor John Williams shows that nature has answers – if we’re willing to harness its power.

Freeing us from fatbergs and floods

"I’ve got a gruesome story," says Professor John Williams.

He describes a recent visit to a sewage works, with a group of students from the ��������.

There, he gave a lecture about the screens which are the first stage of a typical wastewater treatment works.

They’re designed to allow water to flow through for treatment, while catching objects that shouldn’t be there – from wet wipes, to deceased pet goldfish.

When John finished his explanation, a student turned to the process scientist who had shown the group around.

The student asked, "What’s the worst thing you’ve found on the screens?"

After a second’s thought, the scientist answered, "Fingers."

John is a Professor of Environmental Technology at the University. His research focuses on water engineering, with a particular emphasis on water quality.

He and his colleagues have done a lot of work around understanding how wastewater systems are abused by the public.

You may have heard about “fatbergs” which build up and block sewers. Some of the stories in the media resulted from research done at ��������.

Fatbergs are often simplistically described as fat which has solidified. In fact, what happens is that fats, oils and greases from domestic and commercial kitchens undergo complex biochemical transformations when they’re poured into the sewage system.

They react with calcium and other ions that are present in sewage, and create a form of soap. Not that you’d want to scrub your face with a fatberg.

"People put all kinds of things down the drain which they shouldn’t," John explains. "It’s because we have a flush-and-forget mentality.

"People don’t understand what the infrastructure is for and how they connect with the environment. The classic at the moment is cotton buds, which are a particular problem, because a cotton bud just passes through a 6mm screen.

"As they’re not removed, they can end up either in rivers or seas during storms."

A particular challenge is that we are not even aware of some of the harmful things we introduce into wastewater. That’s because, not only are they too small for the screens to stop them, but they’re also too small for us to even see.

Examples include traces of pharmaceuticals which pass out of your body in urine, and microplastics – tiny synthetic fibres which are stripped from clothing in the turbulence of your washing machine, and drain away with dirty water.

A �������� PhD student is currently working on a nationwide project to develop ways of finding out what happens to these microplastics during sewage treatment, and where they end up in the environment (which includes attracting all kinds of pollutants, before being swallowed by fish).

As for John’s own research, he says:

"Breaking through the public awareness barrier is key. We had a big media response when a research paper was picked up by the media as a Christmas story about how turkey fat contributes to the build-up of fatbergs.

"People can relate that back to what they’re doing in the kitchen. If they then start pouring fat into a container instead of down the drain, that’s a step forward."

As important as it is to prevent problems from occurring, much of John’s research looks at developing solutions. He specialises in low impact, sustainable technologies.

This has taken him around the world – from developing technologies to clean up oil fields in Kuwait, to examining contaminated sediments in the Niger Delta. Some of biggest projects happen in the UK.

At ��������, John has a particular advantage. The University has a permanent presence at a full-scale operational sewage treatment works. This enables him and his colleagues to run pilot trials using real sewage, create large data sets and analyse samples in on-site labs.

The power of reeds

In Egypt, South America and the UK, John has done a lot of work with constructed wetlands, using reed beds for wastewater treatment. He explains:

"These are technologies which don’t have the same intensity of energy use, and don’t require so much mechanical plant.

"So, they have applications in rural locations, maybe in the UK, and also in less developed countries where infrastructure is not around to support more energy intensive, mechanically intensive activities."

Right now, John and his team are working with the company Southern Water, exploring the challenges they face at small sewage works in England.

These sites may only treat water for a few hundred people. What’s more, they are often in isolated rural locations, without a lot of infrastructure. Yet modern legislation, including the Water Framework Directive, calls for stringent action to tackle the presence of nutrients, such as phosphorus, in water that is treated.

John says, "The technologies involved have very high requirements for chemicals and storage, which call for large, expensive infrastructure and a lot of energy.

"Across hundreds of small sites, this is not environmentally optimal. Some of these sites don’t have electricity or water supplies, and some are at the end of winding country paths where it’s difficult to get chemical tankers in.

"So we are looking at other ways to ensure compliance with legislation, but which are more economical and sustainable."

The solution is to work with natural processes – harnessing what nature does best, to benefit people and the environment alike. John explains why reed beds often hold the answer:

"Reeds are just incredible for our environmental engineering purposes. They’re incredibly tough and resilient, but more importantly they can grow in flooded conditions.

"So, they can grow hydroponically in gravel, because they have a mechanism to transfer oxygen from their leaves down to their roots.

"Also, reeds can modify their root zones. This means the roots become very intensive sites of microbial activity. If you plant reeds in a swamp which has no oxygen in it, the reed roots will become oxidised, and that usually promotes the breakdown of organic compounds."

These amazing natural capabilities have enabled the �������� to play a part in reed beds becoming a common method of treating wastewater – an ideal, environmentally-friendly solution for small rural sewage works.

John and his team also use the power of reeds to heal contaminated sites:

"We’ve had reeds growing in what we believe are UK record levels of pollution for sediments in terms of petroleum hydrocarbons. Over 100,000mg per kg, and the reeds still grow happily in there.

"As they grow, they’re cleaning up the sediment by stimulating microbial activity. In that environment, it will take decades for reeds alone to clean up. But on a smaller scale, in sewage treatment or a sustainable drainage system, it’s a different story."

Nature does it best

Sustainable drainage is the other side of John’s research. So what is it?

The design of traditional drainage is based around one key factor: getting water away from where it falls, as quickly as possible. Housing developments mustn’t get flooded.

But water doesn’t drain through tarmac surfaces the way it did through the soil that’s now underneath. Instead, it stays on the surface. Solution? Put in a big pipe to carry the water away.

The trouble is, that creates other challenges. Downstream, where the drained water is released, the potential of flooding and pollution is greatly increased. You’ve just moved the problem from one place to another.

By contrast, sustainable drainage is about mimicking the predevelopment hydrology – in simple terms, looking at what happened to the water before you built the houses, road or other infrastructure, and finding a way to recreate that around your development.

One solution is to add open spaces, wetlands and ponds into developments, where water can drain naturally. As John explains, there are multiple benefits to this:

"As well as flood control, you’ve got water quality improvement as it passes through, so improving river water quality and downstream habitat.

"Also, I’ve found people like having habitat within a housing development. Having green space also encourages people to be more active. It improves air quality, too – the benefits can go on and on and on."

But there is a sticking point. Even though UK government guidance and the 2010 Flood and Water Management Act suggest that all new development should have sustainable drainage, the reality is that systems have not been put in place to ensure this.

And developers often prefer economic solutions to ecological ones – for example, it might be less environmentally friendly, but you can build more houses using a giant underwater tank for water storage, whereas you have to build fewer houses if you leave space for wetlands.

John and his team received a green infrastructure innovation grant from the Natural Environment Research Council (NERC). They looked at ways to help developers understand the benefits of sustainable drainage early in the planning stage.

"We delivered 3,000 surveys to residents living on estates with sustainable drainage, to understand their perceptions of the technology, the benefits and the problems.

"We’ve looked at the effect green infrastructure has on house prices and sales. I’ve worked together with quantity surveyors and valuation surveyors at the University, to look at the role of sustainable drainage, and the costings.

"More recently, we’ve developed multidisciplinary teams with colleagues to look at the economic and social aspects."

John enjoys multidisciplinary working. While he’s a scientist by background, many of his projects draw in chemists, biologists, geographers and civil engineers.

Ultimately, what he’s always looking for is greater understanding and proof that concepts work. He doesn’t develop products, but housing developers and water companies can use the knowledge he generates to make a tangible difference in the world.

"We’re using research methodologies to address real world problems," he says. "I’ve always been at the applied end of the spectrum.

"Going back to my PhD, the original motivation for my research was to use natural processes to improve water quality, with all the associated implications for the general environment, and the quality of rivers and habitats.

"I still get such a buzz when I find out something nobody has found out before."

As a result of the NERC project, John hopes that the team’s findings will be adopted into professional guidance by the Royal Institution of Chartered Surveyors. If this happens, it stands to greatly influence the recommendations surveyors make. Given their important role in the development process, this could be the beginning of widespread change.

Understanding and acceptance

John recognises that making change happen is, in many ways, a challenge of psychology.

"In lower income countries," he observes, "people have a much greater connection with the environment, because they’re in contact with it more and using the resources more directly.

"Whereas, in the UK, there’s a barrier. People have switched off from the idea of living with water. There’s a sense that we’ve managed it."

That means, sometimes, when potential buyers visit a housing development which has ponds and wetlands for sustainable drainage, and they find out why those things are there, they are put off.

Why? Because they assume this means the houses will flood – rather than recognising that, in fact, those features are there, in part, to make such a thing less likely.

In considering solutions, John has to think beyond the realms of science and civil engineering.

For example, when it comes to sustainable drainage, while many people say they like nature, it turns out they would rather not see it where they live. They prefer to see neatness, such as trimmed edges of lawns.

"We’re looking at developing some guidance around how you might make something as natural as possible, while still giving visual cues that it’s being cared for.

"Even if you don’t want to get in there and cut down vegetation in the middle, at least trim the grass around the edge and then people might be more accepting. There are some interesting ideas coming out of that research."

As for demonstrating the importance of treating wastewater more mindfully, John is talking to colleagues at the University’s Faculty of Creative & Cultural Industries about putting together an immersive, virtual reality sewer experience:

"We’re trying to understand the ways in which people can make the connection – to realise that when you pull that flush, it’s not the end."

Indeed, for John Williams, it’s just the beginning.