To fight the fatbergs, we need to reinvent the sewers

Mmm, tasty. A flusher holds a piece of fatberg under London in 2014. Image: Getty.

A 250m-long, 130 tonne, “fatberg” was recently discovered clogging up the sewers below Whitechapel in east London. Fatbergs are made up of solidified fat and oils combined with wet wipes, nappies and sanitary products that are disposed of in sinks and toilets.

This wasn’t a unique find: another monstrous fatberg was found in a London suburb in 2013 and, a week after Whitechapel, a slightly smaller “berg” was found under the city’s Chinatown. No doubt there are many more fatbergs still out there, blocking up the sewage system and waiting to be discovered.

There is a simple way to avoid the build up of fatbergs and it relates to everything listed above: bin it, don’t flush it. But many people inevitably adopt the mentality of “out of sight out of mind” and assume it’s not their problem as someone else will sort it. The reality is that clogged-up sewers affect us all, sometimes even causing road closures and flooding.

The UK government has called on London to update its Victorian-era network of pipes and tunnels as, after heavy rainfall, lots of sewage is spilling out into the Thames. To help the capital’s creaky infrastructure cope with a growing population, Thames Water, the local utility, has started work on a huge £4.5bn pipeline that will follow the river through the heart of the city.

But this entire model of large centralised sewers and treatment plants is already starting to look outdated. London’s sewers don’t just need updating – the city needs an entirely new approach to reducing the strain on its sewers.

The problem with big sewers

The key flaw to standard sewers systems is they combine all different kinds of waste into one big mixing pot of chemicals, bacteria and organic waste. A typical household, for instance, has one wastewater stream from the toilet which contains dangerous pathogens, another from the kitchen sink with food waste, and a third from the dishwasher which contains chemicals. All of these require different types of treatment before it is safe to put the water back into the environment.

It’s actually relatively easy to treat one specific highly-concentrated waste stream. Dishwasher waste, for instance, will be around eight to 15 litres of water containing a variety of chemicals to make your cutlery sparkle and, in this concentrated form, UV or ozone treatment can be used to easily remove 99 per cent of them.

But when dishwasher water is combined with all other sorts of waste it then creates a complex cocktail that is much more difficult to treat. Currently, the next step is to dilute everything with rainwater, which vastly increases the volume of water that needs all these elements removed. By the time the waste reaches the treatment plant, dangerous chemicals or substances may make up just one part in a billion of water particles. For instance, a typical sewage works may have to identify and remove just a single raindrop’s worth of benzene, a known carcinogen commonly found in laundry detergents, from a tank of toilet waste the size of a swimming pool.

A sewage works near you

But if treatment was decentralised, with lots of smaller sewage works rather than one big one, most of the contaminants could be removed while they were still in high concentrations. This in turn means waste becomes more useful. Wastewater with lots of food and faeces contains high amounts of energy that can be extracted as “biomethane” gas which can be used for heating or cooking just like regular gas. But when this wastewater is combined with other sources, its energy content is diluted making it more difficult and less efficient to extract.

The solution is to build small treatment plants in new developments or renovations that service smaller areas. A variety of new technologies are being developed: some use electricity to combine different waste particles together into larger clumps so it can be extracted, while others use UV light to breakdown all the chemicals. Some designs let friendly bacteria breakdown the organic compounds producing methane or hydrogen, while others heat up the waste to extremely high temperatures turning it into a gas that can be used to produce electricity or to cook your dinner.

Depending on the needs of the site they could focus on recovering energy or removing chemicals and they could be designed to produce different qualities of water depending on its final use. These small plants could be completely sealed to stop the smell escaping, and quick treatment times would avoid large amounts of smelly waste being stored near the communities.

This way, waste wouldn’t need to travel for miles, mixing with other sources. Instead, it could be treated locally, providing both sustainable energy and clean water.

The ConversationSewage networks were invented by the Victorians and ultimately changed society for the better. But everything evolves and improves with time, and Britain’s water infrastructure should be no exception.

Thomas Philip Fudge is a PhD Researcher in sustainable wastewater treatment at Brunel University London.

This article was originally published on The Conversation. Read the original article.


12 things we learned by reading every single National Rail timetable

Some departure boards, yesterday. Image: CC-BY-SA

A couple of weeks ago, someone on Twitter asked CityMetric’s editor about the longest possible UK train journey where the stations are all in progressive alphabetical order. Various people made suggestions, but I was intrigued as to what that definitive answer was. Helpfully, National Rail provides a 3,717 page document containing every single timetable in the country, so I got reading!

(Well, actually I let my computer read the raw data in a file provided by ATOC, the Association of Train Operating Companies. Apparently this ‘requires a good level of computer skills’, so I guess I can put that on my CV now.)

Here’s what I learned:

1) The record for stops in progressive alphabetical order within a single journey is: 10

The winner is the weekday 7.42am Arriva Trains Wales service from Bridgend to Aberdare, which stops at the following stations in sequence:

  • Barry, Barry Docks, Cadoxton, Cardiff Central, Cardiff Queen Street, Cathays, Llandaf, Radyr, Taffs Well, Trefforest

The second longest sequence possible – 8 – overlaps with this. It’s the 22:46pm from Cardiff Central to Treherbert, although at present it’s only scheduled to run from 9-12 April, so you’d better book now to avoid the rush. 

  • Cardiff Central, Cardiff Queen Street, Cathays, Llandaf, Radyr, Taffs Well, Trefforest, Trehafod

Not quite sure what you’ll actually be able to do when you get to Trehafod at half eleven. Maybe the Welsh Mining Experience at Rhondda Heritage Park could arrange a special late night event to celebrate.

Just one of the things that you probably won't be able to see in Trehafod. Image: Wikimedia/FruitMonkey.

There are 15 possible runs of 7 stations. They include:

  • Berwick Upon Tweed, Dunbar, Edinburgh, Haymarket, Inverkeithing, Kirkcaldy, Leuchars
  • Bidston, Birkenhead North, Birkenhead Park, Conway Park, Hamilton Square, James Street, Moorfields
  • Bedford, Flitwick, Harlington, Leagrave, Luton, St Albans City, St Pancras International

There is a chance for a bit of CONTROVERSY with the last one, as you could argue that the final station is actually called London St Pancras. But St Pancras International the ATOC data calls it, so if you disagree you should ring them up and shout very loudly about it, I bet they love it when stuff like that happens.

Alphabetical train journeys not exciting enough for you?

2) The longest sequence of stations with alliterative names: 5

There are two ways to do this:

  • Ladywell, Lewisham, London Bridge, London Waterloo (East), London Charing Cross – a sequence which is the end/beginning of a couple of routes in South East London.
  • Mills Hill, Moston, Manchester Victoria, Manchester Oxford Road, Manchester Piccadilly – from the middle of the Leeds-Manchester Airport route.

There are 20 ways to get a sequence of 4, and 117 for a sequence of 3, but there are no train stations in the UK beginning with Z so shut up you at the back there.

3) The longest sequence of stations with names of increasing length: 7

Two of these:

  • York, Leeds, Batley, Dewsbury, Huddersfield, Manchester Victoria, Manchester Oxford Road
  • Lewes, Glynde, Berwick, Polegate, Eastbourne, Hampden Park, Pevensey & Westham

4) The greatest number of stations you can stop at without changing trains: 50

On a veeeeery slow service that calls at every stop between Crewe and Cardiff Central over the course of 6hr20. Faster, albeit less comprehensive, trains are available.

But if you’re looking for a really long journey, that’s got nothing on:

5) The longest journey you can take on a single National Rail service: 13 hours and 58 minutes.

A sleeper service that leaves Inverness at 7.17pm, and arrives at London Euston at 9.15am the next morning. Curiously, the ATOC data appears to claim that it stops at Wembley European Freight Operations Centre, though sadly the National Rail website makes no mention of this once in a lifetime opportunity.

6) The shortest journey you can take on a National Rail service without getting off en route: 2 minutes.

Starting at Wrexham Central, and taking you all the way to Wrexham General, this service is in place for a few days in the last week of March.

7) The shortest complete journey as the crow flies: 0 miles

Because the origin station is the same as the terminating station, i.e. the journey is on a loop.

8) The longest unbroken journey as the crow flies: 505 miles

Taking you all the way from Aberdeen to Penzance – although opportunities to make it have become rarer. The only direct service in the current timetable departs at 8.20am on Saturday 24 March. It stops at 46 stations and takes 13 hours 20 minutes. Thankfully, a trolley service is available.

9) The shortest station names on the network have just 3 letters

Ash, Ayr, Ely, Lee, Lye, Ore, Par, Rye, Wem, and Wye.

There’s also I.B.M., serving an industrial site formerly owned by the tech firm, but the ATOC data includes those full stops so it's not quite as short. Compute that, Deep Blue, you chess twat.

10) The longest station name has 33 letters excluding spaces

Okay, I cheated on this and Googled it – the ATOC data only has space for 26 characters. But for completeness’ sake: it’s Rhoose Cardiff International Airport, with 33 letters.

No, I’m not counting that other, more infamous Welsh one, because it’s listed in the database as Llanfairpwll, which is what it is actually called.


This sign is a lie. Image: Cyberinsekt.

11) The highest platform number on the National Rail network is 22

Well, the highest platform number at which anything is currently scheduled to stop at, at least.

12) if yoU gAze lOng into an abYss the abySs alSo gazEs into yOu

Image: author's own.

“For I have seen God face to face, and my life is preserved”, said Thomas.

Ed Jefferson works for the internet and tweets as @edjeff.

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