Hard issue
The Orano desalination plant supplies Swakopmund and mines like
Rössing and Husab with water. In picture is the water pipeline that
runs from the plant inland where NamWater taps into the supply.
The brine stream from the plant is a mixture of the brine from
the RO units, the backwash water from the UF units, and flush
water from the screens. Roughly 70% of the seawater pumped
to the plant is returned to the sea as brine.
Costs of desalination
According to Baillie, the major costs in operating the
desalination plant are the cost of membranes, maintenance,
and electricity. “It is an extreme environment that we operate
in, and therefore the maintenance costs are high,” he says.
He adds that one of the biggest challenges is dealing with
the algal blooms, red tides, and sulphur events that happen
frequently along the Namibian coast. “Because of the
currents, we often experience sulphur outbreaks in the ocean
and when this enters the plant, it creates major problems
in the UF and RO sections. Sulphur is very hard to remove
from the membranes — you have to be careful not to damage
the membranes. As soon as we detect high sulphur levels,
we shut down the plant to protect the membranes. It is a
seasonal phenomenon, but it is more prevalent in summer.”
The EDP is a good example of what mines can achieve and
what contribution they can make to the wider society. One just
has to wonder what will happen if Trekkopje eventually does
start producing uranium? b
www.africanmining.co.za
From the intake, seawater is pumped to the screening plant.
The permeate is passed through a bed of limestone to mineralise it
with calcium carbonate.
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