Environmental Engineering Reference
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energy requirement. Also, with NF pretreatment, the second stage SWRO was no longer
required, which further reduced the capital cost, in addition to the higher productivity.
The energy consumption and cost per unit production (m
3
) at commercial-scale of the
NF-SWRO were estimated to be 23% and more than 46% lower than that of the
conventional RO process, respectively, while at the full scale the savings on energy
consumption and cost were expected to reach 39% and 68%, respectively (Hassan et al.,
2002).
The above review clearly indicated that an effective pretreatment system could
remove not only suspended solids, colloidal materials and organic matters, but also
microorganisms and scalants to enhance the performance and the life-span of the RO
membranes, while reducing overall capital and operating costs.
Advanced research and development will lead to an increase in applications of
nanomembranes not only for the benefits of increasing the product water of a better
quality but also enhanced the possibility of recovering useful materials from the waste
stream. Thus far, nanomembranes have found its applications in potable water
production without the need to remineralize the product water, water reclamation and
recovery of useful materials in industrial wastewater such as dyes and heavy metals, and
reducing the cost for seawater desalination by reducing TDS and hardness prior to RO
membrane. However, many of these applications are still in the R & D stage and would
require further improvements in terms of:
1)
selectivity in the rejection/recovery of materials;
2)
resistance to adverse conditions such as pH, chloride and adverse chemicals
conditions which may be present in the feed water;
3)
durability, stability and reliability of the membrane materials under long term
applications at full-scale; and
4)
lower production cost to provide an affordable option.
The increase in world's population and the decrease in available clean water
sources with the pressing need for energy efficient systems will be the driving force to
provide a sustainable solution in the water beneficiation program. Nanomembranes are
foreseen to be the membrane of the future due to its potential to reduce the energy
requirement for high quality water production.
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