project
31
<< Continued from page 29
1 2
3 4
municipal water — everything comes from the Potsdam
supply, so the building is still off the municipal grid. has a conductivity of less than 30 microsiemens and is
pumped to roof level for reuse.
b) Organic SOG trickle filter
The outflow from the bio-digester system is fed to a SOG or
trickling type organic filter, before being pumped to a feed
tank. This SOG filter is physically comprised of peat-filled
stacked crates within a bund, and makes use of earthworms,
fungi, and bacteria to treat the bio-digester treated sewage
water further. By spreading the type of organism activity, a
larger range of variable flow and load is possible. Organisms
live in the various zones, performing selective functions,
which includes dissolved organic material degradation (COD
reduction), conversion of ammonia to nitrate (nitrification),
and removal of nitrate (denitrification). d) Remote monitoring, feedback, and metering system
Water meters are installed on the municipa l and Potsdam
water supply lines as well as the complete building
and security office. These water meters are connected
to the Airdrive remote monitoring system for real time
monitoring and recording of the complete water usage
of the building via the internet. A control system is also
in place, which detects the water levels within various
holding tanks to ensure correct plant operation and
provides SMS feedback and control.
c) Reverse osmosis water purification plant
The outflow from the SOG filter is pumped into the RO
plant, which filters the liquid down to levels better than
nanofiltration would. The level of purification is so high
that the water has to be re-mineralised after purification
to make it suitable for human consumption. The water
is then pumped through a reverse osmosis membrane
using a high-pressure filter. The resulting purified water
www.plumbingafrica.co.za
1.
2.
3.
4.
Trickling type organic
filter, or SOG filter.
Backflow preventer.
RO plant pre-filtration
and dosing pumps.
Reverse osmosis plant.
In the event of plant failure, or insufficient RO output /
high building demand, the system will automatically and
temporarily switch to municipal water. The water quality
output of the RO plant is also monitored before being
transferred to the building. This system is also connected
to the Airdrive remote monitoring system.
Design conditions
Based on the building gross floor area and
SANS 10252-1, the expected daily potable water
Continued on page 33 >>
May 2017 Volume 23 I Number 3