circularity, its practical results led to low circularity, which started to be challenged
by wet management of human excreta.
2.2 Successful Mutualism (1868–1905)
According to its supporters, the first experiments of sewage spreading on agricultural
land were successful. The community of sewage spreading enthusiasts grew larger
but still had many opponents: doctors who feared that diseases would be widely
spread, fertiliser-makers subjected to competition, owners of buildings who feared
the costs of connection to the sewer, the municipalities who were to receive sewage
on their lands and of course cesspool emptiers who could see their activity disappear
[11]. At the international hygiene congress of 1882 in Geneva, French doctors and
hygienists were among the only people to express fears about mixing human excreta
with sewage water. London had already launched combined sewers in 1858, and
Berlin had made it mandatory in 1874 [12].
The challenge of managing night soil by dry means was also becoming increasingly acute. Between 1868 and 1885, the population had increased by 30% and
collected night soil volumes by 50%. Night soil was becoming more and more
diluted and less and less convenient to convert to fertiliser. Whereas London had
implemented flush toilets and combined sewers without spreading sewage on agricultural land, circularity was considered a sine qua non condition for adopting flush
toilets connected to a sewer in Paris because the Seine had to be protected and the
human excreta recycled.
An intermediary solution adopted in Paris is worth mentioning: the tinette
filtrante (Fig. 4). It consisted of a filtering device installed on a downpipe. It
provided the convenience of having a flush toilet at home with the possibility of
recycling organic matter. The tinettes filtrantes had two major flaws: they were
subject to clogging, leading to overflows; they retained mostly solid matter, such as
faeces or paper, but probably let most of the N, contained in the urine, flow to the
sewer and then to the river. Nevertheless, in the 1880s, tinettes filtrantes peaked at
18% of buildings being equipped with in Paris.
Collection of human excreta in sewers together with spreading on fields finally
came into practice in the 1880s. The connection of houses to sewers was made
optional in 1885 and mandatory after the 1894 tout-à-l’égout law. This law stated
that all houses that were served by the sewer network were compelled to discharge
their excreta in the sewer within 3 years (Fig. 5). The connection rate rose but not as
fast as expected due to various oppositions. There was less than 1% connection in the
1880s, 10% connection in 1895 and already 55% connection in 1905 (Fig. 8).
In a few decades, Paris had shifted from dry collection of human excreta to a
prevailing collection in sewers. Sewage farms increased in size, covering 5,000 ha in
the 1900s (Fig. 6). During this decade, the mean proportion of sewage water spread
on land was 74%. Sewers were collecting more water due to the rise in the
population and water consumption but also more organic matter and nutrients due
126
F. Esculier and S. Barles
by wet management of human excreta.
2.2 Successful Mutualism (1868–1905)
According to its supporters, the first experiments of sewage spreading on agricultural
land were successful. The community of sewage spreading enthusiasts grew larger
but still had many opponents: doctors who feared that diseases would be widely
spread, fertiliser-makers subjected to competition, owners of buildings who feared
the costs of connection to the sewer, the municipalities who were to receive sewage
on their lands and of course cesspool emptiers who could see their activity disappear
[11]. At the international hygiene congress of 1882 in Geneva, French doctors and
hygienists were among the only people to express fears about mixing human excreta
with sewage water. London had already launched combined sewers in 1858, and
Berlin had made it mandatory in 1874 [12].
The challenge of managing night soil by dry means was also becoming increasingly acute. Between 1868 and 1885, the population had increased by 30% and
collected night soil volumes by 50%. Night soil was becoming more and more
diluted and less and less convenient to convert to fertiliser. Whereas London had
implemented flush toilets and combined sewers without spreading sewage on agricultural land, circularity was considered a sine qua non condition for adopting flush
toilets connected to a sewer in Paris because the Seine had to be protected and the
human excreta recycled.
An intermediary solution adopted in Paris is worth mentioning: the tinette
filtrante (Fig. 4). It consisted of a filtering device installed on a downpipe. It
provided the convenience of having a flush toilet at home with the possibility of
recycling organic matter. The tinettes filtrantes had two major flaws: they were
subject to clogging, leading to overflows; they retained mostly solid matter, such as
faeces or paper, but probably let most of the N, contained in the urine, flow to the
sewer and then to the river. Nevertheless, in the 1880s, tinettes filtrantes peaked at
18% of buildings being equipped with in Paris.
Collection of human excreta in sewers together with spreading on fields finally
came into practice in the 1880s. The connection of houses to sewers was made
optional in 1885 and mandatory after the 1894 tout-à-l’égout law. This law stated
that all houses that were served by the sewer network were compelled to discharge
their excreta in the sewer within 3 years (Fig. 5). The connection rate rose but not as
fast as expected due to various oppositions. There was less than 1% connection in the
1880s, 10% connection in 1895 and already 55% connection in 1905 (Fig. 8).
In a few decades, Paris had shifted from dry collection of human excreta to a
prevailing collection in sewers. Sewage farms increased in size, covering 5,000 ha in
the 1900s (Fig. 6). During this decade, the mean proportion of sewage water spread
on land was 74%. Sewers were collecting more water due to the rise in the
population and water consumption but also more organic matter and nutrients due
126
F. Esculier and S. Barles