PROJECT
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Block C original layout.
Block C new plant layout.
underfloor tanks in the links. Effluent was pumped from
these tanks to a standard biological reactor wastewater
treatment plant in Block C.
This system was replaced with a vacuum system, which
effectively reduces the water consumed by toilets and
urinals by 80%. The vacuum system has also made
drainage from the kitchen, laboratories, and medical
facility easier and the link tanks and pumps could be
removed, thus eliminating the maintenance problems
experienced with the old systems’ tanks and pumps.
The vacuum pumps (in Block C) pump the effluent into a
receiving (buffer) tank from where it is transferred to the
new packaged (containerised) effluent treatment plant
installed in the hangar area.
The new effluent treatment plant makes use of Martin
Membrane Systems’ technology and incorporates a
mechanical pre-treatment section with centrifuge, flotation
system, anoxic tank, aeration tank, filtration tank (0.1-micron
membranes), fans, pumps, and the like in a single, easily
maintainable package. The new system is considerably
more efficient in purifying the water, ensuring that only
purified water is pumped over the cliff edge. Sludge is
captured in containers and brought back to South Africa for
safe disposal. The new plant also enables a much smoother
transition between summer and winter effluent loads.
Water generation system
A new snow smelter with increased capacity was
installed just below surface level, approximately 200m
east of the base. Particular attention was paid to increase
the thermal insulation of the snow smelter, increasing the
efficiency of the heating system (in-line heaters versus
the old dry elements) and improving the control system.
Vertically configured Wilo pumps are used for
continued circulation of the water between the two
snow smelter tanks and to pump water to the base.
Inside the base, water is stored in six insulated,
stainless-steel storage tanks that have been installed
against the eastern wall of the hangar. Each tank
has a capacity of 6 367ℓ, providing a total storage
capacity of just over 38 000ℓ.
Water is continuously circulated through the base via a set
of bag filters and an in-line heat exchanger. The decision
to use bag filters of 95 micron was based on two criteria:
less space required comparing a bag to a cartridge system
for the flow rate required, and also because replacement
bags are cheaper compared to filter cartridges.
BMS system
The entire control system was replaced with a
Johnson Controls’ building management system
(BMS) employing current technology. The new BMS
Continued on page 65 >>
www.plumbingafrica.co.za
November 2018 Volume 24 I Number 9