Environmental Engineering Reference
In-Depth Information
that these contaminants can leach out and ind their way back into the groundwater, con-
taminating the local aquifers. This particularly happens for arsenic where the acidic or
reducing conditions in the landill can break apart the arsenic ferric oxide complex, releas-
ing the toxic arsenic into the ground.
Using nanotechnology, researchers worldwide are looking for better and more cost-
effective ways for treating metallic contamination and alternatives for reverse osmosis
for conserving water while treating it for brackishness. Use of nanotechnology provides
a means for increasing the effectiveness and loading capacity of adsorbents by deposit-
ing nanoscale particles on a substrate. These adsorbents need to be further developed
to allow recovery of metallic material such as arsenic from the spent adsorbent so that
they provide a more cost-effective way of producing metallic arsenic that can ind uses
in the semiconductor industry, in medicines for treatment of cancer, or in metallurgical
applications for improving alloy properties.
22.4 Other Challenges
WaterHealth is addressing drinking water needs of communities, whether rural, peri-
urban, or urban, by installing treatment centers, some or most of its installations can be in
remote areas that have challenges of their own. Any new technology that is developed to
address the water treatment needs of population residing in these areas also has to over-
come these challenges for the technology to be practical and viable. The following sections
enumerate some of these challenges.
22.4.1 Temperature, Humidity, and Dirt
To keep the energy required to a minimum, dwellings are generally not designed with any
air conditioning and are generally kept open to allow circulation of air. In India, average
ambient temperatures in the summer can reach over 45°C; at times during peak sum-
mer, temperatures may touch 50°C. In the arid regions and in regions where vegetation
has been removed, winds can kick up a cloud of dust. During monsoon season, humid-
ity can be over 95% accompanied by high temperatures. These environmental extremes
place undue stress on electronic components. Generally, if water is drawn from the source
and treated immediately, system temperatures may not reach the severe environmental
temperatures due to cooler water temperatures. However, if the water is stored outside in
plastic tanks that are blackened on the outside, water temperatures may be higher than
the environmental temperature, and if used, can subject the piping, vessels, and treatment
media to these elevated temperatures, requiring that the materials used in the water treat-
ment system maintain their integrity and functionality at elevated temperatures and in
most cases compounded by elevated pressures.
22.4.2 Accessibility
It is not given that all communities will have accessibility by wide or paved roads.
Invariably, one may have to travel by dirt washboard roads that are narrow and bumpy.
Water treatment equipment needs to be rugged and compact to withstand the transporta-
tion as well as allow passage through narrow crowded roads.
