Recently, many large-scale seawater desalination
plants were built in water-stressed countries to increase water resources. The
development of desalination technologies can attain either by process
performance improvement or by using of hybrid systems. Renewable energies can
be combined with desalination (thermal or reverse osmosis) to produce more
NF–MSF and NF–RO–MSF combination with power plant can
reduce capital costs, and enhance the plant efficiency. Dual-stage NF process is a promising seawater desalination technology.
In addition, by comparing with two stage RO process, RO/NF hybrid process has
lower investment costs and electric energy. Ion exchange–nanofiltration
desalination is advanced low energy process, but its applications is limited
till now due to higher costs and lower working life of ion exchange resins.
The recent concept of coupling FO with another
process to realize hybrid FO-based systems for desalination has been proposed
to capitalize FO in a more advantageous way. FO/RO hybrid system for desalination is a
promising system in case of high TDS draw solution (such as seawater) but it is
not benefit in case of low TDS draw solutions (such as brackish water). The use
of a hybrid FO system integrated with distillation column for desalination of
high salinity shale gas produced water with specific energy consumption lower
than other thermal distillation methods.
Solar desalination units can eliminate carbon
emissions and produce water with minimal impacts on environment and highly
suitable for rural areas where power is not possible. Solar powered RO technique
solve the problem of high electrical energy cost of RO process, in addition,
PRO/RO hybrid system was can simultaneously overcome water and energy shortage. While, integrated membrane system which comprises
multiple membrane types is an efficient way of improving the overall process
performance by decreasing; fouling, energy consumption, and operating cost.