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But this entire model of large centralised sewers and treatment plants is already starting to look outdated.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.


To fix the housing crisis, we need to decide what success would look like

Building houses in Ilford, 1947. Image: Getty.

Recent years have seen growing public and political recognition that there is a crisis in housing. This has led to a widening debate on the causes and potential solutions.

However, within this debate there has been little in the way of a consensus view of what constitutes the current housing crisis – or what a “crisis-free” housing system might look like. There seems little clear idea of any measurable goal. The nearest we have as a target to aim at has been a series of aspirational numbers for new-build homes, with limited clarity on what to expect if we were to hit those numbers.

Clarity about what success would look like is essential. Without a framework for what we need and want from housing, our ability to understand and fix it appropriately will be compromised. A lack of clarity also increases the risk of unintended consequences from misguided policy interventions.

The current housing debate is, to quote UCL’s Michael Edwards, “bedevilled by rival simplifications”. There are several, quite often competing explanations for why we have a housing crisis. For many it is our failure to build homes at the same rate as projected household formation. This failure might be assigned to the planning system, the greenbelt, housebuilder business models, the land market, or NIMBYs.

For others, the crisis is a result of falling interest rates, rising credit supply, low income growth, wealth and income inequality, tax incentives, or simply our fixation on house price growth. For some, there is no shortage of homes, rather a poor distribution. And for others there isn’t really a housing crisis.

Despite the apparent contradictions in this mix of positions, each of the arguments that support these various views may hold significant elements of truth. Housing is a complex and interconnected system within the economy and society. There is no simple single housing market: there are multiple markets defined by location, property type, tenure, and price. Therefore, there is no simple single housing crisis. Instead we have multiple overlapping issues affecting different parts of the country in different ways and to varying degrees.

There may be factors that influence all housing markets across the UK, indeed across much of the globe. There will be others that impact more locally and within specific housing sectors.

So, for instance, there is growing acceptance by many experts that the cost and availability of credit has been one of the biggest, if not the biggest, drivers of increases in national house prices over the last twenty years.

But it is not the only factor. The growth in buy-to-let has contributed to the financialisation of housing, with homes increasingly thought of as an investment rather than a place for people to live. A lack of supply is predominantly an issue for London and its surrounds, but there are localised shortages elsewhere, particularly of specific types or tenure of homes.

Planning (including a lack of) and the land market limit the responsiveness of supply to rising demand. Housing is unevenly distributed, mostly across generations but also spatially and within generations. Some areas don’t need a net increase in housing but desperately need existing poor-quality homes improved or replaced. In many areas the biggest issue is low (or negative) income growth and employment insecurity.

All these issues and others play a part in defining “the housing crisis”. Having a framework for what we need and want from housing, combined with an understanding of the complexities and interactions that run through the housing market, is essential to resolving the problems they create.

The problem with ‘households’

A misunderstanding of the complexities of housing can be found in one of the most frequently stated explanations for the crisis: a lack of new supply compared with household projections.

Unfortunately, this argument is flawed. Household projections are not a measure of housing demand. The effective demand for new housing is determined by the number of people or companies willing and financially able to buy property. Meanwhile new supply only accounts for around 12 per cent of total transactions and probably less of available homes for sale.

Importantly, even if some analysis may suggest there is no shortage of supply, that does not mean there is no need for new supply. Household projections are a statistical construct based on the past, not a direct measure of future housing demand. But they are still important if used appropriately within a framework for what we need and want from housing.

If we are more explicit about the role of household projections in measuring housing need and the assumptions they contain, then the ‘supply versus household projections’ argument might be recast as a debate on changing household sizes and the consumption of housing (both in terms of space and multiple properties).

This then implies that we should be clearer about the minimum acceptable amount of housing people need, while also accounting for what they want. Should younger people still expect to form households at the same rate and size as their parents? The assumptions and projections around future household sizes should be moved from the background, where they are typically only discussed by planners and researchers, to the centre of the debate.

They should be just one part of a framework for success that explicitly states what we need and want from housing – not just in terms of size but also cost, tenure, quality, security, and location – and better defines the minimum we are prepared to accept. That will provide a clearer understanding of where housing is failing to meet those requirements and help set objectives for how to fix it. These could then be applied appropriately across different markets.

“Rather than trying to return to the relatively short-lived 20th century ideal of mass home-ownership, perhaps we should be focussing our efforts on making renting cheaper”

If measurement against the framework shows that households are not able to form at an appropriate rate and size relative to what they need, then we probably need to increase supply while possibly encouraging older households to move out of larger homes. If rents are too expensive then we may need to reform the rental sectors and increase supply. If housing quality is poor, then we need to work harder at improving and replacing existing stock. If many areas are struggling due to low (or negative) income growth and employment insecurity, then we probably need to look beyond just housing. It might even question whether we need to rebalance the economy and infrastructure investment away from London and its commuter zone.

Having a framework for success may even highlight which issues we can fix and which we can’t. For example, it looks likely that we are stuck with a low interest rate and hence high house price to income market. Under those conditions, prospective first-time buyers will continue to struggle to raise a deposit and access home-ownership irrespective of how much new supply can be realistically delivered.

Rather than trying to return to the relatively short-lived 20th century ideal of mass home-ownership, perhaps we should be focussing our efforts on making renting cheaper, higher quality, and more secure as a long-term home. Increasing new supply would be an important tool in achieving that outcome.

When we have a framework for what success could look like, our ability to understand and fix housing appropriately will be dramatically improved. It would be an important step towards making housing available, affordable, and appropriate for everyone that needs it. It would also be more useful than simply setting a nice round number national target for new homes.

Neal Hudson is an independent housing analyst, who tweets as @resi_analyst. This article originally appeared on his blog.