Water, Sewage & Effluent March April 2019 | Page 10

City’s ‘untreated’ sewage destroying marine life
“All the chemicals that we use in our
daily lives go with the grey water, faeces
and urine that are mixed together and
disposed of into the sea,” added Petrik.
She said the research had been an effort
to investigate and monitor shore-based
pollution at Camps Bay and Green Point,
possibly caused by the sewage outfall.
Recently they had found several
dangerous chemical compounds such
as diclofenac, an anti-inflammatory
agent, in snoek and other fish bought
from Kalk Bay harbour. Petrik says
that dilution of pollution was no
solution, especially since these
chemical compounds bioaccumulate
and move up the food chain. “If you
are discharging sewage to the ocean,
you are going to cause a great deal
of ecological destruction because of
the very problematic chemicals that
are in the sewage. The fish stocks are
collapsing, and this may not be because
of overfishing and climate change but
because of chemical contaminants,
yet nobody talks about the impact that
these chemicals have on the fertility of
marine organisms. The level of these
compounds is not being monitored,”
said Petrik.
Water
and
Waste
Mayoral
Committee (Mayco) member Xanthea
Limberg said: “In all but three of the
city’s 20-plus wastewater treatment
plants, tertiary treatment methods
are employed. The remaining three
employ only preliminary treatment
and dispose of wastewater via a long
pipe extending out to sea, called a
long marine outfall. The outfall dilutes
the effluent to reduce contaminant
concentrations far below what can be
achieved with even advanced sewage
treatment, and the distance to the coast
ensures that bacteria are dispersed or
die before they can come into contact
with bathers.
“Long-term scientific monitoring, in
terms of the water quality standards
applied to the city’s beaches, has
confirmed that the city’s outfalls do not
pose a significant risk to human health
and that the environmental impact
is confined to the area within the
immediate vicinity of the outfall pipe.
“Incidences
of
substandard
water quality at beaches are mainly
attributable to pollution events such
as blocked/overflowing sewers, or
stormwater ingress — especially
after rainfall where pollution from the
streets is washed into the stormwater
pipes and eventually out to sea. In our
decades of testing, it has emerged that
low water quality is strongly correlated
with rain, especially the first rain of the
season,” said Limberg.
Source: IOL 
Cape Town’s seas and its creatures are
exposed to a high volume of harmful
bacteria, chemicals, pharmaceutical
drugs — including antibiotics — as well
as cleaning agents.
This is according to Professor Leslie
Petrik of the University of the Western
Cape’s chemistry department, who
tested the water and sea life off the
city’s coast.
Petrik said there was a continual
release of chemicals, with the
sewage being poured into the ocean
daily, which could endanger marine
organisms. The sewage pollution also
had a negative impact on the fertility
of the marine organisms. “This has
been ongoing research. The pollution
[happens when] disposing the sewage
from all the city’s premises — from
offices, hospitals, and homes.
“All the sewage that is collected from
the central city is being discharged
at the Green Point marine outfall. All
the sewage from Camps Bay is being
discharged through the marine outfall
in Camps Bay and all the sewage that
is collected from Hout Bay is being
discharged through a marine outfall in
Hout Bay,” explains Petrik. “This means
that the sewage is not treated but is just
being screened to remove big objects
like nappies; everything else goes to the
ocean without treatment.
With Cape Town’s sewage being poured into the ocean daily, and with it the continual release of chemicals, marine organisms could
be endangered.
8
Water Sewage & Effluent March/April 2019
www.waterafrica.co.za