Water, Sewage & Effluent November December 2018 | Page 34

Warka Water’s water-collecting tower.
Atmospheric water generation
1
China has developed machines to extract water from air,
and with a minimum requirement of 30% humidity, these
machines are the answer to a consistent supply of potable
water. Table 1 illustrates the amount of water that can be
extracted from the various humidity levels.
Table 1 1
Humidity (%) 35 40 50 60 70 80 90
Production capacity (ℓ) 10 14 18 22 25 30 33
Importer H2O Is Life strives to find a variety of renewable
resources for its clients, with the focus on water, ranging
from rainwater harvesting, greywater filtration and AWG,
through to energy generation with solar and wind. The
entry-level machine can produce up to 33-litres of potable
water in a 24-hour period with an operating wattage of 450–
500W and total current of around 2A. Cost per litre is R2.50.
The company has formed partnerships with Air to
Water on the supply of best-of-breed AWG machines and
their brand of bottled water: Flow – For Love of Water.
2
Ancient systems for modern application
Bedouin farmers in Jordan’s Wadi Rum desert region
are using permaculture design systems, which date
back to the ancient Nabateans who once inhabited
the region.
These systems help conserve available water
supplies to successfully grow organic vegetables and
other crops. Permaculture irrigation involves digging
small canals and drip irrigation methods. The systems
used have already been in use extensively in the Jordan
Valley. Mulching around trees such as pomegranates
involves using what is known as a ‘chopndrop’ method
that helps conserve water.
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Water Sewage & Effluent November/December 2018
Available are two countertop units, the A2W 15ℓ and A2W
20ℓ. Both units stand comfortably on a counter and they
blend in nicely with other appliances, producing pure
organic drinking water, while the A2W 33ℓ and A2W 50ℓ
units are stand-alone.
Then for larger capacity needs, there is the A2W SL Series,
designed to meet the requirements of hospitals, hotels,
schools or business, ranging from 500ℓ up to 20 000ℓ daily.
The A2W Mobile units are 20ft ISO containers that can make
up to 5 000ℓ of water within 24 hours, while the A2W CWP
Aquafer can supply an entire community with water, even if
no water provision solution is currently in place.
Another low-tech invention for harvesting water from
the air is the Italian-designed Warkawater Tower, designed
to collect water in countries like Ethiopia during evening
hours when the air becomes cooler. Named after the warka
tree, native to Ethiopia, special plastic mesh in bamboo
frameworks collect dew, which then drips down to a
collecting pan. This method requires no external energy and
is well suited for arid countries like Ethiopia where night-time
temperatures are often very cool, allowing dew to form.
3
Fog harvesting
Fog harvesting involves collecting water droplets
created in locations where dense fog often blankets
areas during certain times of the year. Also known as
fog drip, this method of collecting water is now being
used in Middle East countries like Yemen, Oman, and
Saudi Arabia, where annual monsoons create dense
fog, known as ‘Khareefs’, which blanket southern
coastal regions.
In this method, fog-created water droplets are
captured on special plastic mesh, which then drips
down into a special reservoir located below the mesh.
A collector of four 20-metre-wide, 3-metre-tall nets is
placed at opposite ends of a reservoir that is capable
of holding 400 cubic metres of water.
www.waterafrica.co.za