project
27
Bespoke water
treatment system
for Old Mutual Wealth
The Estuaries Plaza has installed a bespoke waste water treatment and
purification system, which is self-sufficient and enables a virtually water
neutral facility to operate.
By Ilana Koegelenberg, with input from Sutherland Engineers
The Estuaries Plaza building in Century City, Cape
Town, consists of three floors of general offices
and one level of basement parking. The total usable
area is 3 173m². Each office floor is served by a
set of male and female restrooms as well as a
small kitchenette area. The basement parking also
contains a security office with small kitchenette and
restroom area. Restrooms and kitchens have local
hot water geysers. All drainage water is collected at
the basement level.
A waste water treatment and purification system
(WWTPS) has been installed at the plaza. This
system uses recycled waste water from the building
as well as make-up recycled water from the local
municipality waste water treatment plant at Potsdam
and purifies it to a potable standard. This water is then
reticulated throughout the building using copper piping.
Primary purification occurs through reverse osmosis
filtration and is supported by organic filtration and
treatment processes.
All water usage is monitored by electronic water meters.
The purification plant and water meters are linked
to a GSM-controller for real time control, as well as
monitoring and recording of the building water usage.
Potable water consumption has been reduced by
approximately 88.5% against the Predicted Potable
Water Rating Benchmark.
www.plumbingafrica.co.za
Waste water treatment
and purification system
The WWTPS was installed at basement level. Waste
water from the building is directed to this system, which
purifies the water to potable level and recirculates it for
reuse in the building. The complete water purification
process comprises three primary components: a bio-
digester, an organic media trickle filter (also referred to
as a SOG filter), and a reverse osmosis (RO) plant.
Black water and grey water drainage from the building
is diverted to four bio-digester tanks located in the
basement. The drainage is broken down into methane
gas and treated water. The methane gas is extracted for
use with a gas cooking stove.
The treated water is then directed through a SOG filter.
The SOG filter uses organic peat to filter the treated
water organically. The SOG filter treated water is
pumped into a RO process. Pre-filtration at 100 micron,
20 micron, and finally five micron occurs. The treated
water is then pumped through a membrane filter by
use of a high-pressure pump and diverted by a buffer
tank. This purified potable water is available for reuse
in the building.
In addition to the purified potable water, the RO
discharges a nutrient-rich brine discharge. This mass
flow loss is recuperated by the use of recycled water
from the local municipality waste water treatment plant
Continued on page 29 >>
May 2017 Volume 23 I Number 3