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History of ecosan - Causes for abandoning recovery of nutrients from human excreta (and Wikipedia article on ecosan)
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- neilmacleod
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- Consultant in water and sanitation, Honorary Research Fellow at UKZN
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Re: Reply: History of ecosan - Causes for abandoning recovery of nutrients from human excreta (and Wikipedia article on ecosan)
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You need to login to reply- KumiAbeysuriya
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- Independent sustainable development researcher with a passion to enable developing countries and communities to ‘leap frog’ to the leading edge of sustainable urban sanitation services.
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Re: History of ecosan - Causes for abandoning recovery of nutrients from human excreta (and Wikipedia article on ecosan)
Thank you for initiating this topic!
I can add a little more background to how the miasma theory contributed to the abandonment of nutrient recycling in England. It was a confluence of several historical factors - the state of scientific knowledge, colonisation that enabled alternative guano-fertilizer to be sourced, the abundance of water at the time …
(I’m copying from an article I wrote, and attaching a diagram that shows how the timing made this possible).
A series of cholera epidemics ravaged London in the 1800s focusing public attention towards solving urban public health problems. The well established medical theory about the cause of these and other diseases was the inhalation of miasmas or malodorous disease-causing vapours, so that removal of decomposing miasma-causing substances as promptly as possible appeared a logical strategy for improving public health. To use water as a transport medium for effecting this rapid removal was feasible, since water resources were abundant due to relatively high precipitation rates in Europe at the time, and stormwater drainage canals already installed in early industrialising cities could be used for movement of wastewater. Water-carriage technology was also desirable, because its automation represented advancement in scientific and economic terms, since economic growth has generally been equated with the substitution of human energy by other forms of energy. Finally, although the dilution of nutrients in large volumes of water made agricultural reuse difficult, the availability of alternative fertilizers in imported guano and nitrates around this time made it possible to abandon attempts at recycling wastes for agriculture.
The timing of the contextual factors had a vital influence on the outcome of the sanitary revolution, and it is intriguing to speculate how a different context might have turned out. In particular, if the germ theory had been established at the time, whether mixing and dispersing disease-causing germs in water might have appeared less logical. Or, whether discarding excreted nutrients would have been possible, if alternative fertilizers had not become available right at that time.
Warm regards,
Kumi
Independent Consultant
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You need to login to reply- joeturner
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Re: History of ecosan - Causes for abandoning recovery of nutrients from human excreta (and Wikipedia article on ecosan)
adlib.everysite.co.uk/adlib/defra/conten...doc=262994&id=263072
Of course, as discussed above, sewage sludge is not the same as fresh excreta, there is an issue with metals and other contaminates and so on. But there is a genuine agricultural value in reusing the treated sludge from an industrial sewage works.
Also, of course, the characteristics of urine or untreated (or differently treated) excreta is going to be different.
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You need to login to reply- joeturner
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Re: History of ecosan - Causes for abandoning recovery of nutrients from human excreta (and Wikipedia article on ecosan)
Peak Phosphate is discussed as (opposed to Peak Nitrogen) because of the different way that the nutrients behave in the environment. Nitrogen is indeed high in urine as urea, but unlike phosphate there are other ways to get nitrogen ions into the soil (for example some plants are able to get it directly from the atmosphere). In contrast, phosphate can only be obtained from rock phosphate (ie mined) or reused.
In one sense the Peak Phosphate discussion is an economic one (about the future supply of rock phosphate) which is a bit irrelevant, given all of the phosphate which is being washed into the seas and causing an environmental problem - and which could be collected and reused. Even if it doesn't run out, there is still a big negative in terms of the Planetary Boundary of inefficient use.
Another point is that the excreta needs to supply the needs of the plants. Many soils are actually short of P, so the limiting factor for plant growth might be P rather than N. Applying more that is actually being used may just lead to the nutrients being washed out of the soil (or lost to the atmosphere) and causing a problem somewhere else.
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You need to login to reply- joeturner
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Re: History of ecosan - Causes for abandoning recovery of nutrients from human excreta
Interestingly, that link suggests that the waste was collected by a night-soil man.
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You need to login to reply- Elisabeth
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Re: History of ecosan - Causes for abandoning recovery of nutrients from human excreta
I should perhaps start a "history" section on the page about "dry toilets":
en.wikipedia.org/wiki/Dry_toilet
(rather than putting everything only in the history section of the ecosan page:
en.wikipedia.org/wiki/Ecological_sanitation#History)
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Re: History of ecosan - Causes for abandoning recovery of nutrients from human excreta
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You need to login to reply- bracken
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- Working throughout Africa since 1996 in development cooperation. Involved with sustainable sanitation systems since 2002. Currently working for the AHT GROUP AG (a private consultancy office in Germany).
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Re: History of ecosan - Causes for abandoning recovery of nutrients from human excreta
Firstly, the introduction of water flushed sewers made the reuse of excreta in agriculture more difficult due to the massively increased volumes of material and the very nature of the wastewater transported (mixed flows of unknown origin). Even the sewage farms (which were not a universal part of early wastewater treatment systems) had problems dealing with the volumes. And what were originally farms using wastewater transformed with time into something else and were not used for agricultural production. Here is a good example: beddingtonfarmlands.org.uk/1998-2008/4535562136
Secondly, sewage sludge spreading is again something different from using wastewater for irrigation and a pretty controversial topic. I personally see it more as a poor solution for the solid waste problem for wastewater treatment plants and certainly not a convincing example of nutrient recovery from human excreta.
And thirdly, the fact that the social reformers were not willing to accept the fact that lives were cheap is what lead to the end of the terrible social and working conditions of the time. These poor conditions and the political will to change them drove change.
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Re: History of ecosan - Causes for abandoning recovery of nutrients from human excreta
bracken wrote:
Regarding sewage farms, the sewage collected in Victorian London was actually discharged into the Thames estuary and not reused on farms. ("Contrary to Chadwick's recommendations, Bazalgette's system, and others later built in Continental Europe, did not pump the sewage onto farm land for use as fertilizer; it was simply piped to a natural waterway away from population centres, and pumped back into the environment." from en.wikipedia.org/wiki/Sewage_treatment).
Sewage certainly was pumped into the sea, but several sewage farms were in operation in London and Royal Commissions from the 1850s actually recommended reuse on the land to protect waterways. See this: www.sewerhistory.org/articles/trtmnt/1910_abs503/article3.pdf
The sewage farms were used towards the end of the 19th Century rather for inland towns where disposal at sea or into a water body was not an option - it was not the direct application of human faeces on fields but the use of sewage effluent on fields, which is something quite different I would contest.
True. And indeed throughout the 19 century the worry was as much about managing the industrial effluents in the sewage rather than the faeces itself.
Even these though became overloaded as the population increased and the land many of them occupied was then used to build more efficient sewage works (and possibly retained the name "sewage farm" although no farming continued on the site).
It is not clear what you mean here. Landspreading of sewage sludge from sewage works is a common disposal mechanism of treated faeces in England.
I would dispute that people were that cheap in Victorian London, given the political power of the social reformers, including Chadwick, and writers such as Dickens, and the way in which society was transformed by them.
Well, I'm sorry that is just wrong. Throughout the 19 century the working poor were seen as disposable and were engaged in occupations which it was known would lead to serious illness and death.
For example in the matchmaking industry, Dickens highlighted the damaging effects of white phosphorus matches in the 1850s but they were continuously manufacturered through to 1910 - even though there was much evidence of health damage to workers. There were many occupations where conditions were so dangerous that people were expected only to survive for a few years.
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You need to login to reply- bracken
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Re: History of ecosan - Causes for abandoning recovery of nutrients from human excreta
Regarding sewage farms, the sewage collected in Victorian London was actually discharged into the Thames estuary and not reused on farms. ("Contrary to Chadwick's recommendations, Bazalgette's system, and others later built in Continental Europe, did not pump the sewage onto farm land for use as fertilizer; it was simply piped to a natural waterway away from population centres, and pumped back into the environment." from en.wikipedia.org/wiki/Sewage_treatment). The sewage farms were used towards the end of the 19th Century rather for inland towns where disposal at sea or into a water body was not an option - it was not the direct application of human faeces on fields but the use of sewage effluent on fields, which is something quite different I would contest.
Even these though became overloaded as the population increased and the land many of them occupied was then used to build more efficient sewage works (and possibly retained the name "sewage farm" although no farming continued on the site). I would dispute that people were that cheap in Victorian London, given the political power of the social reformers, including Chadwick, and writers such as Dickens, and the way in which society was transformed by them.
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Re: History of ecosan - Causes for abandoning recovery of nutrients from human excreta
The stink and the idea of miasma led to the construction of sewers in London but I think this was more of a transportation issue than because they understood it in terms of it as a source of pathogens. People were cheap in Victorian England, and people were still required to work the faecal wastes on farms.
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You need to login to reply- bracken
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- Working throughout Africa since 1996 in development cooperation. Involved with sustainable sanitation systems since 2002. Currently working for the AHT GROUP AG (a private consultancy office in Germany).
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Re: History of ecosan - Causes for abandoning recovery of nutrients from human excreta
Just to clear up what you said in your second point.
The discoveries of Snow (1854) and Pasteur (also mid 1800s) almost certainly DID NOT initially contribute to the collapse of the reuse system, as the germ theory was not widely accepted at the time that Bazalgette's work on London's sewer began (subsequent to the Great Stink of 1858). Just check out the Lancet's own editorial on Snow's discovery:
www.ph.ucla.edu/epi/snow/reactionandcommitteeaction.html
It was the Great Stink that moved the British Parliament to commission the construction of the first modern sewer, not the Broad Street Pump affair and discovery that cholera was water borne. And the modern, water flushed sewer is something that made nutrient recovery much more difficult.
I would agree though that germ theory did eventually (certainly by the turn of the century) lock in the water-borne sewer and encourage widespread "faecophobia".
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