So how can we prevent fatbergs?

Eww: a piece of fatberg in the streets beneath London. Image: Getty.

Fatbergs – enormous solid masses of oil, grease, wet wipes and other hygiene products that congeal together to cause major blockages – are wreaking havoc on the sewers of cities around the world. A 130 tonne specimen described as a “monster” recently caused backups in sewers in London’s Whitechapel, and the cities of Baltimore, Singapore and Dannevirke, New Zealand have also all experienced similar issues in recent weeks.

Fatbergs are not a recent phenomenon, but have attracted increased attention in recent years as old sewerage systems struggle to cope with an increased consumption and disposal of everyday products like fats, oils and greases from cooking. This is a particular issue for cities like London with Victorian systems. The visceral disgust that runs alongside the image of fatbergs lingering under the city, and the potential impact they will have on local flooding, means that they will remain a topic that demands attention.

Strategies are already being put in place in order to prevent sewer fatbergs. Current water industry tactics tend to focus on removing sewer blockages and reducing the fats, oils and greases that enter sewers from commercial sources (such as restaurants). But around three quarters of the fats, oils and greases in sewers comes from domestic sources, making household disposal a key priority for change.

Awareness campaigns directed at the public currently focus on what people put down the kitchen sink. Current advice is that cooking fats, oils and greases should be disposed through food or solid waste recycling. But there is little information on how we can dispose of other products – like that fatty off milk at the back of the fridge – without pouring it down the sink. The mucky complexities of how people actually deal with fats, oils and greases in the home suggests that the solution might need to be more complex than awareness campaigns.

In a recent report we suggest that changing people’s broader behaviour related to food waste and disposal of fatty products is not going to be easy to change – and that we also need to look beyond the plughole.

Down the plughole

Fats, oils and greases are changeable, often smelly, visceral materials. The way we dispose of them is tied to attempts to reduce their impact on our kitchens and in our lives, and this becomes entrenched in our everyday habits and routines.

They can be troublesome materials to handle. The fact that they are liquid at cooking temperatures, and often at room temperature, makes them simpler to dispose of via liquid waste than via solid waste channels, yet their tendency to solidify and accumulate in the specific physical and chemical conditions of drains and sewers makes this disposal highly problematic. Fats, oils and greases are not only difficult to deal with, but many also find it unpleasant.

Evidence from research into food waste and disposal suggests that when food begins to deteriorate, its material properties – and the bodily reactions caused by its appearance, smell and feel in the people handling it – play an important role in how it is discarded. The more effectively and reliably it can be sealed off and ejected from the home with minimal human contact, the better.

Our research suggests that if the same is true of householders’ reactions to leftover fats then successful interventions to divert fats, oils and greases from sewers will mean providing an alternative, yet similarly effective, option for quick and seemingly hassle-free disposal than the kitchen sink.

These ideas of disgust, dirt, smell, and convenience are also likely underpinning similar dynamics for the disposal of wetwipes, nappies, and other hygiene products down the toilet rather than the bathroom bin.

Beyond the kitchen sink

But crucially, fats, oils and greases do not end up in our sewers purely due to decisions related to disposal at the kitchen sink. Rather, actions throughout the stages of food provisioning – including shopping, food preparation, cooking, dealing with leftovers, and clearing up – leads to fats, oils and greases entering sewers.

Another way of thinking about the issues is in regards to tracing the numerous decisions that occur in the process of carrying out routine household tasks: moments in which resources are used up and waste is produced. This is broader than just individual behaviours and involves a consideration of all of those moments where waste fat is indirectly or directly produced – such as when we are choosing what to cook; how much oil to use; whether to reuse that rendered meat fat from the Sunday roast in the next meal we cook or discard it.


Insights into what shapes behaviour at these points lead to a range of implications and recommendations for policies and intervention programs. For example, there needs to be a recognition that disposal of products like fats, oils and greases is part of a wider set of kitchen practices that are in turn shaped by wider systems of food provision (supply chains, retail, and so on) as well as waste disposal facilities.

Interventions that influence household behaviour therefore don’t just need to target the household but could involve product innovations that reduce likelihood of excess fat oil and grease production – for example, fryers that use less fat. Retail environments and packaging could be used as means of changing social norms. Sewerage systems could be rethought. Effective alternative waste fat and oil disposal infrastructures could be envisioned.

The ConversationRather than fatbergs just being seen as a water industry issue there needs to be greater collaboration across sectors (water, energy, food) to deal with the problem. Potential solutions need to range from the level of the household right through to new infrastructures that are experimenting with turning this mucky fatberg problem into energy and biofuel.

Alison Browne, Lecturer in Human Geography and the Sustainable Consumption Institute, University of Manchester and Mike Foden, Postdoctoral Research Associate, Keele University.

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

 
 
 
 

What can other cities learn about water shortages from Cape Town’s narrow escape from ‘Day Zero’?

Cape town. Image: Pixabay/creative commons.

Cape Town was set to run dry on 12 April, leaving its 3.7m residents without tap water.

“Day Zero” was narrowly averted through drastic cuts in municipal water consumption and last-minute transfers from the agricultural sector. But the process was painful and inequitable, spurring much controversy.

The city managed to stave off “Day Zero,” but does that mean Cape Town’s water system is resilient?

We think not.

This may well foreshadow trouble beyond Cape Town. Cities across the Northern Hemisphere, including in Canada, are well into another summer season that has already brought record-setting heat, drought and flooding from increased run-off.

Water crises are not just about scarcity

Water scarcity crises are most often a result of mismanagement rather than of absolute declines in physical water supplies.

In Cape Town, lower than average rainfall tipped the scales towards a “crisis,” but the situation was worsened by slow and inadequate governance responses. Setting aside debates around whose responsibility it was to act and when, the bigger issue, in our view, was the persistence of outdated ways of thinking about “uncertainty” in the water system.

As the drought worsened in 2016, the City of Cape Town’s water managers remained confident in the system’s ability to withstand the drought. High-level engineers and managers viewed Cape Town’s water system as uniquely positioned to handle severe drought in part because of the vaunted success of their ongoing Water Demand Management strategies.

They weren’t entirely mistaken — demand management has cut overall daily consumption by 50 per cent since 2016. So what went wrong?


Limits to demand management

First, Cape Town’s approach to water management was not well-equipped to deal with growing uncertainty in rainfall patterns — a key challenge facing cities worldwide. Researchers at the University of Cape Town argued recently that the conventional models long used to forecast supply and demand underestimated the probability of failure in the water system.

Second, Cape Town’s water system neared disaster in part because demand management seemed to have reached its limits. Starting late last year, the city imposed a limit on water consumption of 87 litres per person per day. That ceiling thereafter shrunk to 50 litres per person per day.

Despite these efforts, Cape Town consistently failed to cut demand below the 500m-litre-per-day citywide target needed to ensure that the system would function into the next rainy season.

The mayor accused the city’s residents of wasting water, but her reprimanding rhetoric should not be seen as a sign that the citizens were non-compliant. The continuously shrinking water targets were an untenable long-term management strategy.

Buffers are key to water resilience

In the end, “Day Zero” was avoided primarily by relying on unexpected buffers, including temporary agricultural transfers and the private installation of small-scale, residential grey-water systems and boreholes in the city’s wealthier neighbourhoods. The former increased water supply and the latter lowered demand from the municipal system. These buffers are unlikely to be available next year, however, as the water allocations for the agricultural sector will not be renewed and there is uncertainty in the long-term sustainability of groundwater withdrawals.

For more than a decade, Cape Town has levelled demand, reduced leaks and implemented pressure management and water restrictions. This made Cape Town’s water system highly efficient and therefore less resilient because there were fewer reserves to draw from in times of unusual scarcity.

The UN Water 2015 report found that most cities are not very resilient to water risks. As water managers continue to wait for climate change models to become more certain or more specific, they defer action, paralysing decision-makers.

If we really want our cities to be water-resilient, we must collectively change long-held ideas about water supply and demand. This will require technological and institutional innovation, as well as behavioural change, to create new and more flexible buffers — for example, through water recycling, green infrastructure and other novel measures.

Although Cape Town avoided disaster this year, that does not make it water-resilient. Despite the arrival of the rainy season, Cape Town is still likely to face Day Zero at some point in the future.

The ConversationThere’s a good chance that the city is not alone.

Lucy Rodina, PhD Candidate, University of British Columbia and Kieran M. FindlaterUniversity of British Columbia.

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