Environmental Engineering Reference
In-Depth Information
Microbial Contaminants Removal
in a Stormwater Pond
Thomas J.R. Pettersson and Johan Åström
Introduction
Stormwater contaminants discharged from urban areas are often considered as
threats limited to the receiving waters since the contaminants mainly being viewed
as environmental degradation agents rather than, for example raw water degrading
agents. To reduce the load of stormwater contaminants the most efficient action in
a long-term perspective is the practice of source control, but when acute short-term
remediation actions is needed stormwater ponds have showed to be a good measure
to reduce contaminants and to achieve cleaner and healthier water bodies [1] favor-
ing the implementation of the European Water Framework Directive where all
waters including rivers, lakes, coastal waters and ground waters should reach “good
status” by December 2015 [2] . The pollution reduction efficiency of stormwater
ponds mainly depend on the physical processes that govern the sedimentation of
particulate bound pollutants [1] . This is also valid to the removal of microbial con-
taminants in stormwater ponds, and of great significance to prevent drinking water
sources from pathogens carried in stormwater. To ensure drinking-water safety,
microbial as well as chemical and physical hazards need to be assessed. In a public
health perspective the microbial contaminants may be of more importance for the
society compared to chemical and physical contaminants [3] . Pathogens in natural water
catchments may originate from various human and animal sources, and cause water-
borne infections through consumption of contaminated drinking water. The management
of faecal contaminants from human and animal sources in urban catchment areas
depends on the type of sewer system. For separate sewer systems, animal faeces from
roads and impervious areas may be transported in the stormwater and enter the
receiving water without further treatment. Stormwater is known to carry substantial
amounts of faecal bacteria [4, 5] and a few studies have reported the presence and
survival of pathogen in wetlands and stormwater ponds [6-8] .
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