Developing sense around ‘fatbergs’
UCD engineer Dr Tom Curran is on a mission to stop ‘fatbergs’ from clogging up sewers. He spoke to Dr Claire O’Connell about developing new technology to fight the build-up of hidden fat.
Fatberg alert! A gigantic, greasy lump creeps along the sewers under a city, clogging the pipes and forcing foul-smelling sewage out above ground. It sounds like the script of a horror movie, but it’s an event that is all too real for the cities where it has happened. Fatbergs form when households and restaurants put fats, oils and grease (FOGs) into the dishwasher or down the sink, and flush products such as nappies and wet-wipes down the toilet.
The congealed waste mounts silently in wastepipes, and the resulting fatberg can restrict the flow of wastewater and sewage until the problem spills out above ground. Then the fat mountain often needs to be manually shovelled and power-hosed away so that the waste can flow freely again.
But UCD engineer Dr Tom Curran is on the case. He and colleagues are looking at interventions that prevent or minimise the impact of fatbergs, and his newest project will develop a suite of sensors to warn of impending clogging so that action can be taken quickly.
“A fatberg blocking a sewage pipe is like a blockage in an artery,” explains Dr Curran, a lecturer in UCD School of Biosystems and Food Engineering and Director of the MSc in Environmental Technology Programme at UCD. “And just like in the body, if the blockage occurs in a major artery, or pipe in this case, the results can be quite serious, with gas and sewage backing up and emerging into streets and premises.”
The resulting mess can not only damage roads and gardens and pollute rivers, but fatbergs can also potentially risk the health and lives of humans who need to physically climb into sewers and remove the troublesome blockages with shovels and high-pressure jets.
Some fatbergs are enormous – in September this year a 250-metre blockage that gummed up a sewer in East London weighed an estimated 130 tonnes (the equivalent mass of 19 African elephants, according to The Guardian). Last summer, the ‘Dublin Road’ fatberg in Belfast congealed close to fast-food outlets and crews had to shovel the blockage out over a number of Sunday mornings.
This year, Dr Curran and colleagues published a review in the Journal of Environmental Management of international measures to tackle fatbergs. They include educational campaigns such as ‘Cease the Grease’ in the USA and ‘Bin it – Don’t block it’ in the UK, he explains: “The awareness around fatbergs tends to peak when there is a problem in the local sewers.”
Dublin has had much success in preventing the formation of fatbergs thanks to stipulations that restaurants need to install and maintain a grease trap to hold back the fatty materials before they get into the sewer.
“Dublin is one of the leading cities in the world for these preventive measures,” says Dr Curran. “In 2008 Dublin City Council implemented rules about managing fats, oils and grease and it has reduced the fatberg problem in Dublin by about 95 per cent. It made a big difference.”
Dr Curran is now working with a FOG stakeholder group in the UK to develop free, easy-to-understand visual instructions so that kitchen staff know how to avoid adding to the fatberg problem, and his group in UCD partners with award-winning Irish start-up SwiftComply, which offers restaurants an online platform to manage their fat, oil and grease waste.
By their nature fatbergs are an invisible problem, but the chaos they ultimately cause can be extreme and costly, from environmental problems to traffic diversions. “Often we only find out a fatberg is there when it starts to cause damage,” says Dr Curran, who wants to develop a sensor-based ‘early warning’ system to alert when trouble is brewing.
Building on his previous research funded by the Irish Research Council, he has now won a prestigious Fulbright TechImpact Award to work with Professor Joel Ducoste in North Carolina State University on a fatberg detection system.
They have been very helpful with their expertise in electronics and they have helped me to use a dedicated ‘Internet of Things’ network for the project that Science Foundation Ireland is rolling out on Irish campuses, including UCD
“In the first instance, we want to identify areas of high risk,” explains Dr Curran. “So we will map out where restaurants are in relation to sewers, taking into account the diameter and conditions of the sewers, and calculate ‘hotspots’ where fatbergs are more likely to occur.”
This information will determine where a suite of sensors could be stationed to monitor the sewer for early signs of trouble, and Dr Curran is preparing to put such sensors through their paces starting early next year.
“I’m looking to put sensors under manhole covers so we can monitor the level of sewage, which would start to rise if there was a blockage, as well as the flow rate, which would slow if a fatberg is forming and also an increase in the levels of gases from a build-up of waste material,” he explains.
All the right connections
While Dr Curran had expected to have to review off-the-shelf sensors to determine the best types to use, a conversation with another Fulbright awardee, Dr Jacek Kibilda, and his colleagues from the CONNECT Centre in Trinity College Dublin have helped Dr Curran to leapfrog over that search.
“They have been very helpful with their expertise in electronics and they have helped me to use a dedicated ‘Internet of Things’ network for the project that Science Foundation Ireland is rolling out on Irish campuses, including UCD,” says Dr Curran. “In return, I can help their work by collecting data using the sensors I will put in place under manhole covers for my test projects.”
Dr Curran hopes that the fatberg sensor system could ultimately give authorities a warning that a blockage is forming. “If they know that, then crews could be dispatched early to deal with it before problems arise,” he says. “And this would help to protect the health of those crews and the wider environment.”
How not to build a fatberg
Prevention is better than cure, and when it comes to fatbergs that clog up sewers, the idea is to avoid loading fats, oils, greases and sanitary products into sewers in the first place.
Dr Tom Curran has some expert advice to heed in the kitchen when cooking with fats and oils and cleaning up afterwards. “If you are having a fry, let the pan heat up so you use less oil,” he says. “That will save you money too.”
Then once you are ready to wash up, be sure to let any fats, oils or grease cool, and don’t be tempted to wash them directly down the sink with hot water to speed their passage. “As a rule, fatbergs tend to occur around 300 metres from the point of discharge because fats have had a chance to cool down and harden,” says Dr Curran.
Instead, he recommends that you wipe fats off pans, utensils and crockery into the bin for food waste.
As for the bathroom, be aware that not everything that seems flushable is good for sewers, he cautions. “Wet wipes have become a big problem in last 10 years,” he says. “People often think they can be flushed down the toilet and some say they can be on the pack. But while a lot of things are flushable, they are not suitable and they can contribute to the fatberg problem.”