The addition of chemical disinfectants is another option to consider. More
recently, full-size experiments were conducted in one of the Paris WWTPs by adding
performic acid. Performic acid degrades very rapidly, producing free radicals that
inactivate microorganisms. Reduction rates up to 2.5 and 2.7 log units have been
obtained for E. coli and IE, respectively, with a concentration at the outlet much
lower than 100 bacteria per 100 mL for each of the FIBs (unpublished data).
Endocrine disruption tests on amphibian and fish larvae (up to 4 days exposure)
did not show any significant additional impact of the chemically oxidized water.
These encouraging results, for chemical and UV disinfection, must be confirmed by
an analysis of their potential for degradation of viruses and other pathogens given
that many of them require a more stringent treatment for the same efficacy.
A second source of fecal contamination to rivers is poor connection to sewers.
This most important issue will both affect base dry weather contamination fluxes and
contribute to the contamination brought by rain events. Solving this problem
requires a very detailed, time-consuming, and complex project to check all connections, starting from the most impacting catchments and organizing the proper
reconnection of identified the buildings identified, which is under the responsibility
of private individuals. It is certainly a highly delicate challenge for the recovery of a
sufficient microbial water quality in the Marne and Seine rivers. Meanwhile, a
complementary effort is needed to reduce urban runoff by infiltration or storage of
rain water.
10 Conclusion
The water quality of the rivers that cross urban spaces is a concern for all
[66]. Affected in their quality of life and their need for “nature,” Parisians and the
Ile-de-France region’s inhabitants wish to reclaim the river to satisfy their needs and
participate in new leisure and sports activities. The idea of a “swimmable city” was
born in 2015 [67] with considerable interest on the part of local actors along the
Marne River. In Paris and in its region, it became a strong political issue for the
mayor of Paris and in the perspective of the 2024 Olympic Games. The expected
activities also involve mobilization of all users of the Seine and Marne rivers (e.g.,
boatmen, industrialists, sports associations) to better preserve the quality of water
and avoid conflicts of use.
This approach is part of a geopolitical context (competition between major cities
regarding the attractiveness of the living environment and the development of the
sustainable city) and local politics (institutional power related to the reorganization
of the area, economic development, etc.). Meeting the demand of the population in
their desire to win back the Seine and Marne rivers without compromising their
health is one of the mobilizing issues of all the actors involved, from scientists to
managers, as well as users and decision-makers, all responsible for the quality of the
Seine and Marne rivers and their usage.
Bathing Activities and Microbiological River Water Quality in the Paris. . .
349
recently, full-size experiments were conducted in one of the Paris WWTPs by adding
performic acid. Performic acid degrades very rapidly, producing free radicals that
inactivate microorganisms. Reduction rates up to 2.5 and 2.7 log units have been
obtained for E. coli and IE, respectively, with a concentration at the outlet much
lower than 100 bacteria per 100 mL for each of the FIBs (unpublished data).
Endocrine disruption tests on amphibian and fish larvae (up to 4 days exposure)
did not show any significant additional impact of the chemically oxidized water.
These encouraging results, for chemical and UV disinfection, must be confirmed by
an analysis of their potential for degradation of viruses and other pathogens given
that many of them require a more stringent treatment for the same efficacy.
A second source of fecal contamination to rivers is poor connection to sewers.
This most important issue will both affect base dry weather contamination fluxes and
contribute to the contamination brought by rain events. Solving this problem
requires a very detailed, time-consuming, and complex project to check all connections, starting from the most impacting catchments and organizing the proper
reconnection of identified the buildings identified, which is under the responsibility
of private individuals. It is certainly a highly delicate challenge for the recovery of a
sufficient microbial water quality in the Marne and Seine rivers. Meanwhile, a
complementary effort is needed to reduce urban runoff by infiltration or storage of
rain water.
10 Conclusion
The water quality of the rivers that cross urban spaces is a concern for all
[66]. Affected in their quality of life and their need for “nature,” Parisians and the
Ile-de-France region’s inhabitants wish to reclaim the river to satisfy their needs and
participate in new leisure and sports activities. The idea of a “swimmable city” was
born in 2015 [67] with considerable interest on the part of local actors along the
Marne River. In Paris and in its region, it became a strong political issue for the
mayor of Paris and in the perspective of the 2024 Olympic Games. The expected
activities also involve mobilization of all users of the Seine and Marne rivers (e.g.,
boatmen, industrialists, sports associations) to better preserve the quality of water
and avoid conflicts of use.
This approach is part of a geopolitical context (competition between major cities
regarding the attractiveness of the living environment and the development of the
sustainable city) and local politics (institutional power related to the reorganization
of the area, economic development, etc.). Meeting the demand of the population in
their desire to win back the Seine and Marne rivers without compromising their
health is one of the mobilizing issues of all the actors involved, from scientists to
managers, as well as users and decision-makers, all responsible for the quality of the
Seine and Marne rivers and their usage.
Bathing Activities and Microbiological River Water Quality in the Paris. . .
349