Keywords Membrane · Porous · Nonporous · Pressure-driven · Thermal gradient ·
Electrically driven · Reverse osmosis · Ultrafiltration · Nanofiltration · Forward
osmosis · Size enhanced ultrafiltration · Electrodialysis · Liquid membrane · Hybrid
membrane processes · Water recovery and recycle · Wastewater treatment ·
Membrane bioreactors · Membrane solvent extraction · Value recovery · Point-ofuse device
8.1 Introduction
In the current scenario, water has become a scarce commodity compared to its free
availability as a natural resource. The transformation is basically triggered by
increase in population and the consequent growth in industries, agriculture, and
lifestyle conveniences. Further, the supplies have dwindled due to a variety of
reasons including climate change resulting in skewed rainfall pattern, inefficient
use of water, pollution, overexploitation of groundwater, etc. This calls for an
approach whereby demand is decreased and supply is increased. Demand can be
reduced by improving water use efficiency, economizing specific consumption on
various products and activities, quality use linkages, and recovery and reuse of water
from spent streams. Supply augmentation can be achieved by improving the collection and storage efficiencies of natural resources including rain harvesting, linking
the different sources of water to guard against avoidable overflows, and using
desalination technologies in coastal areas.
Water being a universal solvent carries along with a variety of chemical species,
essential minerals, and toxic components both in dissolved and suspended states. It is
necessary that humans get safe water and the industries get water as per their
requirement. Since most of the sources are contaminated physically, chemically,
and biologically, water treatment is necessary. The contaminants of natural water can
be either geo-genic or anthropogenic in origin. The former depends on the local
geology, while the latter depends on human activities surrounding the water source.
Conventional method of water treatment is primarily point-of-source treatment
requiring chemicals and large footprint area. The treatment process is also quite
sensitive to operating parameters such as pH, efficiency of mixing, and dosage of
chemicals and generates significant amount of sludge for disposal.
The early 1980s witnessed the induction of large-scale commercial desalination
plants based on reverse osmosis, and the subsequent phenomenal growth of membrane desalination over the conventional thermal processes has triggered the development of membrane applications in other areas of water treatment. The entire water
treatment scenario has changed consequently with reference to time, efforts, and
costs for both domestic and industrial uses. Since the late 1990s, a variety of
membrane processes have been developed to suit different streams of water requiring much less footprint area and chemical requirement. These membrane processes
8 Role of Membranes in Wastewater Treatment
249
Electrically driven · Reverse osmosis · Ultrafiltration · Nanofiltration · Forward
osmosis · Size enhanced ultrafiltration · Electrodialysis · Liquid membrane · Hybrid
membrane processes · Water recovery and recycle · Wastewater treatment ·
Membrane bioreactors · Membrane solvent extraction · Value recovery · Point-ofuse device
8.1 Introduction
In the current scenario, water has become a scarce commodity compared to its free
availability as a natural resource. The transformation is basically triggered by
increase in population and the consequent growth in industries, agriculture, and
lifestyle conveniences. Further, the supplies have dwindled due to a variety of
reasons including climate change resulting in skewed rainfall pattern, inefficient
use of water, pollution, overexploitation of groundwater, etc. This calls for an
approach whereby demand is decreased and supply is increased. Demand can be
reduced by improving water use efficiency, economizing specific consumption on
various products and activities, quality use linkages, and recovery and reuse of water
from spent streams. Supply augmentation can be achieved by improving the collection and storage efficiencies of natural resources including rain harvesting, linking
the different sources of water to guard against avoidable overflows, and using
desalination technologies in coastal areas.
Water being a universal solvent carries along with a variety of chemical species,
essential minerals, and toxic components both in dissolved and suspended states. It is
necessary that humans get safe water and the industries get water as per their
requirement. Since most of the sources are contaminated physically, chemically,
and biologically, water treatment is necessary. The contaminants of natural water can
be either geo-genic or anthropogenic in origin. The former depends on the local
geology, while the latter depends on human activities surrounding the water source.
Conventional method of water treatment is primarily point-of-source treatment
requiring chemicals and large footprint area. The treatment process is also quite
sensitive to operating parameters such as pH, efficiency of mixing, and dosage of
chemicals and generates significant amount of sludge for disposal.
The early 1980s witnessed the induction of large-scale commercial desalination
plants based on reverse osmosis, and the subsequent phenomenal growth of membrane desalination over the conventional thermal processes has triggered the development of membrane applications in other areas of water treatment. The entire water
treatment scenario has changed consequently with reference to time, efforts, and
costs for both domestic and industrial uses. Since the late 1990s, a variety of
membrane processes have been developed to suit different streams of water requiring much less footprint area and chemical requirement. These membrane processes
8 Role of Membranes in Wastewater Treatment
249