What we are talking about here is how we, Society, deal with our Sh1t! And how it has evolved over last 300 years or so. A little history lesson of the commercialisation of sh1t moving. Sh1t (human) believe it or not, was 300 years ago and up to a point now is very valuable.
The night soil men of old dug out the human dung from the privy carted it away in a horse and cart during the hours of darkness and sold it to the local farmers to spread on the land as fertiliser.
Proving the old adage, "Where there’s Muck, there’s Brass!”
This process of usage continued and could be described as a closed loop sustainable system – you eat - you shit - it gets moved back onto the land to fertilise it - which grows crops to perpetuate the system again.
The system with some tinkering continued up and until the take off of the Industrial Revolution and the Victorian Age. This age marshalled in a plethora of Public Health initiatives primarily because people were now living in very close proximity to each other in their 1000s, causing illness, disease and death to run rampant. Colah being one of the worst killers through human faeces just being thrown or drained right into the streets contaminating the available drinking water supplies. We’ve all seen the period dramas of the Piss Pots being just thrown from the upper windows into the street below.
The Victorian fathers recognising through increased and growing knowledge of how illnesses etc spread through the population realising they needed to do something to stop the impacts on the ever-growing population. That something was to create the Sewage System below ground, much of which is still with us today.
The systems they created where and still are in most cases combined sewers. Combined meaning they took domestic, industrial and rainwater in the same pipes to the same place. The same place in the early days being the local river. The hiatus of what they had done wrong was what is known as the Thames Stink and why MPs have summer recess. The smell of the river was that bad and nauseating they vote not to sit during high summer. Being MPs, they failed to return to sitting when the stink was irradicated.
They then included rudimentary sewage works to treat the water before it was released into the river. As most rivers that ran through major conurbations mirrored what was happening on the Thames, sewage works were created in and around those conurbations. A mention here should be made that at the same time as these “improvement” to the sewage system were being done, so to was the supply of clean water for drink, cooking etc and the creation of reservoirs to hold the water needed for the growing populations of the UK.
The creation of sewage treatment and disposal was a double-edged sword in the sense it broke the closed loop of the preindustrial revolution. It introduced vast volumes of water into the system via flush toilets, where prior to it the only water in the system was possibly urine. Which in itself was a valuable commodity, as it was used in the tanning industry and was collected and sold to that industry. The introduction of water into the system and running it into the rivers killed off much of the life in rivers around the conurbations, a legacy we lived with until the 1980s when the river systems biologically started to improve. The reverse of which has been happening since around 2010.
In creating this wholly water bases system of a combined sewers we have made it very difficult to get on top of river pollution for these two reasons.
The water has to be got rid of somewhere and given the volume it the rivers and sea were the only option. Contained within that water are chemicals that can’t be taken out and are lethal or sublethal to aquatic life.
We must move away from the water bases sewage system. Whilst it is true, in a small way we have started to move away from some water going down the pipes to the sewage treatment works (STWs) by making every new houses built use what is called SUDS (Sustainable Urban Drainage System) for rainwater. Effectively, the rainwater runs to soak-a-way either in a purpose built pond on a housing estate or around the house and into the ground. It may be a sound or not principle, it’s to early to tell, as it not been running long enough to show up any medium to long term problems. What it clearly does do is leave the remaining water in the system concentrated with the contaminants it has. Ergo the really nasty stuff from industry and domestic household products.
Moving on to what to do with the sludge from the STW, which is highly concentrated with very few of the toxins from the above sources remove. I heard it suggested it could be used as fertilizer on farmland. The Problem with that is you can only apply 3 applications to the land because of the toxins/chemicals in it as it is now. Those I’d suggest would need to be lowered because you have concentrated them by reducing the overall water volume of the sludge.
Incinerate them perhaps? Not if you want to reduce your CO2 levels you can’t! The nature of some of those toxins/chemicals they must be burnt at 1300c plus.
I even heard CEO of a new company/process on the radio the other day waxing on about how his process could turn sludge into pellets and put back on the land as fertilizer. Never occurred to him or the presenter that the pellets would have all the inherent toxins/chemicals problems of spreading wet sludge on the land.
The problem of disposing of Sewage is as near an intractable one to say the least. Is it an insurmountable one? Probably not but will cost a large amount of money to remedy but that should not be a barrier to doing it.