Happy Thought for 29 November 2024

Have a Happy Thought:  

 

One huge benefit of living in modern cities is the infrastructure, often unseen or ignored by many, that keeps our cities clean, and us healthy. Even if we do know about things like sewers and stormwater pipes, (Yes, I know that many of my readers are VERY aware of this critical infrastructure – but today’s post might still be news even for you!) we don’t often know the history of why we have what we have, today. 

 

For example, I recently learned how bird poo led to combined sewer systems. (Combined sewers are very common in the modern western world, although many are being replaced now with separated stormwater and sewage/wastewater systems. They’ve probably been in your local news in the last year.) 

 

A VERY simplified agriculture and history lesson first: plants need food to grow – we usually call this “fertilizer”. A very good source of fertilizer, if properly used, is human waste – often throughout history this was called “nightsoil”. If nightsoil is not properly used (or collected or otherwise contained), it can spread lots of disease. As cities grew larger and more crowded, and further separated from agricultural land, “nightsoil” really started to contaminate rivers, streets, water sources (wells), etc.  

 

By the mid 1800s in England especially, the situation was pretty dire, and engineers were finally financed to fix the problem. And this is where things started to improve... but they could have been so much better. 

 

Many of you will have heard of John Snow, the epidemiologist who proposed (without fully knowing it) a germ-theory for cholera. He went against the prevailing theories that cholera, and other diseases, were simply caused by miasma – or bad smells. Because most of society believed that smells were the problem, the best solution seemed to be to divert all the bad smelling stuff into the river and get it away from people as quickly as possible.  

 

There were two main competing designers to remove sewage from the city streets:  

• Joseph Bazalgette, wanted a combined brick-lined sewer system 

• Edwin Chadwick, who wanted to capture human waste separately for use as fertilizer 

 

Here’s where bird poo comes into the story. The other major factor that led to people devaluing “nightsoil” was... guano.  This is extremely nutrient-rich bird droppings, and also has the benefit of not carrying some human-specific diseases that need to be carefully managed when it comes to using human nightsoil as fertilizer on food crops. Basically, in the mid 1800s it was easier to ship guano to England from South America and Africa than to collect local human waste. There were even books written and advertisements about the wonders of guano! 

 

By Allison & Addison - http://scriptorium.lib.duke.edu/eaa/ephemera/A02/A0291/A0291-01-72dpi.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=10360515 

 

Between the ubiquity of guano for fertilizer, and Joseph Bazalgette’s superior social skills (Chadwick seems to have “fallen out” with supporters, politicians, engineers, ratepayers, the list goes on...), the combined sewer system was given the nod in London. And most of modern cities ended up copying this basic design. (Before we judge our past city planners too harshly, there are a lot of benefits to combined sewer-stormwater systems, such as the fact that heavy rains will “flush” a sewer system – which will not happen in fully separated pipes. Also, having sewers really did save a LOT of lives, and continue to do so, to this day!) 

 

And in case you’re still not sure that infrastructure is worth spending your time thinking about, let this Hollywood-style movie trailer with big-name stars convince you 😊 

https://youtu.be/Wpzvaqypav8?si=B-EopZ9VDNbCY9lj&t=1064 

 

Thanks to the Rare Earth podcast https://www.bbc.co.uk/programmes/m001wrhm for bringing this to our attention! 

Thanks to John Oliver and Last Week Tonight for highlighting modern cities’ unsung heroes. 

 

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Also posted to:    

cymittw.blogspot.com