
In a startling discovery, a colossal fatberg weighing 130 tonnes and stretching over 250 metres was unearthed in the East London sewers in 2018. Composed of congealed fats, oils and non-biodegradable waste like wet wipes, this monstrous blockage threatened the sewer system, with an extensive removal operation taking nine weeks. The fatberg underscored the need for public awareness regarding what waste to put down the drain.

Hi. I’m Arno. I’m with the Aquanauts.
We’re wild about water and how to make sure there’s enough for everyone who needs it now and in years to come.
Here at Aquanaut HQ, we’re diving into FOG! No, not the misty weather – Fats, Oils and Grease are some of the yucky stuff that ends up in our sewers and why it’s a big challenge for the future.

While fats, oils and grease might seem harmless, once they’ve been used, they cool, solidify and stick to whatever they against.
If that’s the inside of a pipe, well… that can restrict the flow and lead to blockages which not only disrupt where we live and work but also affect the environment, polluting rivers and harming wildlife.
Using detergents and bleach to get rid of blockages might appear to help but often it’s only a temporary measure as the FOG soon turns back to thick solid mass.
It’s a problem that’s not going away. As more and more people eat out, the number of food outlets increases and the amount of FOG entering our sewers rises.
Aquafact – 75% of sewer blockages in the UK – that’s around 200,000 every year, are caused by Fats, Oils and Grease – costing millions of pounds to clear.

Technology is helping solve the problem.
Interceptors or Grease Traps, can be installed in drains to catch FOG before it can cause problems. There’s a huge number of different types. There’s compact units under sinks which slow water flow, allowing grease to float and solids to settle.
Then there are larger tanks used by restaurants and commercial kitchens which have baffles to control flow, allowing more effective separation of grease. A third type are really heavy-duty, in-ground units for high-volume use like in hotels, hospitals and by industry. These can even filter and recycle water for reuse. One thing all these traps have in common is that the collected fat has to be removed often by hand.

Alongside the traps, food outlets can install macerators which chop and grind food into small pieces to help easier disposal. There’s still a risk of blockages, so basically, it’s always better to put food waste in the bin and not down the drain.
Aquafact – Enzyme Dosing Systems use special bacteria-produced enzymes that breakdown the FOG in the grease traps.
When we think about waste water, it’s important to get an idea of the scale of the problem. Even producing the food we eat creates an enormous amount of waste water which can contain a lot of pollutants. This needs to be treated to avoid damaging the environment, and that might mean biological and physical-chemical methods such as flotation, filtration, coagulation, as well as aerobic and anaerobic digestion. It’s not just food that causes problems in the water system.
There are all sorts of pollutants that make their way into our water supply… chemicals from factories, small molecules of heavy metals and even microplastics from everyday items. They all cause problems and harm the environment.
Aquafact – Exciting new technology is using genetically modified bacteria to detect pollutants in the water supply with an electrical device, which is much quicker than having to do complicated tests in a laboratory.
Something that’s meant to make us better can actually cause harm to ourselves and the environment… and that’s medicines!
Medicines can be a big problem in that they can hang around in water for a long time. Scientists have found that they can affect aquatic life in really dramatic ways – antidepressants have been found in fish brains altering their behaviour, whilst hormones from contraceptives have caused fish to develop both male and female characteristics. In time, these pollutants might also make it harder for humans to reproduce.

But how do the medicines get into the water supply?
Medicines enter water systems when we wash or go to the toilet. People might also dispose of unwanted pills and liquids down the drain. They can also enter as by-products from the factories and laboratories that produce them.
The good news is that there are advanced wastewater treatment technologies in development. These include steps such as activated carbon filtration where pollutants are absorbed into the carbon.
One way your grown-ups can help you become Aquanaut is by taking unused medicines back to the pharmacy so they can be safely disposed of. For fats oils and grease, don’t pour them down the drain, put them in the rubbish bin! Aside from anything else, you’ll avoid getting a mini fatberg blocking your sink!
You can also explore a career in water engineering and technology.
Water Workers

There’s a wide range of jobs across the water sector and today’s water worker is Mechanical Engineers!
Mechanical engineers design power-producing machines, such as electric generators, internal combustion engines, and steam and gas turbines, as well as power-using machines, such as refrigeration and air-conditioning systems. They also design other machines inside buildings, such as elevators and escalators.
The water industry relies on lots of processes that use machinery – from interceptors and traps to filtration plants and the tech needed to shift fatbergs! These are all designed, built and maintained by mechanical specialists.
Take the challenge!
The Mini Sewage Treatment Plant activity demonstrates the fundamental process of water filtration, helping you understand how sewage treatment plants clean wastewater before it is released back into the environment. Ready? Download here!
Want to know more?
‘This is Engineering’ is an initiative led by the Royal Academy of Engineering in partnership with EngineeringUK and major engineering organisations to encourage young people from all backgrounds to consider a career in engineering. Click HERE to find out more… or perhaps visit the Museum of Engineering Innovation.
Stick with us… we’re going to be helping you understand the challenges ahead, and discover some of the cool engineering and careers that are helping solve the issues. We’re also going to find out how we can all make a difference with more tips on how you can become an Aquanaut and help engineer our water future!
