Water Sewage & Effluent May/June 2018
innovations
Chris Braybrooke, Veolia
"As conventional sources of
freshwater become increasingly
strained in the face of increasing
urbanisation and population
growth, cities will need to look at
alternative sources of ensuring
their future water security."
resource. As conventional sources of
freshwater become increasingly strained
in the face of increasing urbanisation
and population growth, cities will need
to look at alternative sources of ensuring
their future water security. Water reuse,
which can be treated to a wide spectrum
of quality grades for industrial or potable
use, is a critical component of these
strategies.”
The technologies exist to clean and
treat even the dirtiest of wastewater
to a potable standard. That is achieved
by the Goerengab Plant, which uses
sludge treatment technologies and
processes to recycle wastewater and
semi-purified sewage to a standard that
is 100% safe for human consumption,
and which supplies approximately a
third of the City of Windhoek’s potable
water supply.
The 47.5Mℓ/day of municipal and
industrial effluent recycled by the DWR
plant, on the other hand, is treated purely
for industrial reuse by the industrial
processes of the city’s high-volume
water users like SAPREF and Mondi.
“This water is supplied at half the cost
of conventional bulk water, reducing
these customers’ overall water costs
while freeing up a significant volume of
potable water, which allowed the city to
expand its existing bulk infrastructure to
previously unserviced communities in the
greater metropolitan area,” Braybrooke
explains.
Industrial
facilities
are
also
implementing their own on-site
wastewater treatment plants to
treat and recycle waste streams for
internal reuse in a drive to achieve
zero liquid discharge (ZLD). As such,
they are reducing their dependence
on municipal wastewater works,
optimising water use costs, increasing
self-sufficiency in guaranteeing a
stable water supply, and minimising the
risk of environmental contamination.
Water is not the only precious
resource that can be produced
from sludge, however, and, more
and more, dewatered solids from
the sludge treatment process that
were previously destined for landfill,
are being selectively harvested
and reused.
At Ambatovy Mine in Madagascar,
Veolia technologies are used to
extract over 200 000 tons of ammonium
sulphate per year, which is sold to the
agricultural industry.
“What was initially conceived of as
a significant, potentially harmful
solid waste ‘problem’, is now a
secondary revenue stream for the
mine that offsets production costs
and thus improves profitability,”
says Braybrooke.
High COD waste streams contain
latent, usable energy through the
BioThelys plants use biological sludge reduction technology.
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