3. Since the concentration of the heavy metal species are so low, the consumption of
additives would be very small,
4. Ultrafiltraton is backwashable, and hence the complex can be recovered as such in
a backwash cycle.
5. Further, most of the complexation or adsorption processes are sensitive to
pH. Hence, after size enhancement and separation of heavy ions, the size
enhancement can be reversed by altering pH or other conditions, enabling the
separation and recovery of metal ion species as well as the complex for reuse.
Removal of copper, nickel, and chromium has been extensively studied using
a variety of complexing agents such as polyethylenimine (Sarkar et al. 2013;
Kadioglu et al. 2010), carboxymethyl cellulose (Kavitha et al. 2018), and
chitosan derivative (Kavitha et al. 2019). The removal of cesium and strontium,
the radioactive contaminants of nuclear waste from the supernatant solution (after
cesium was co-precipitated along with copper ferrocyanide and strontium as
phosphate), indicated that size-enhanced ultrafiltration can be used as a last
mile separation process (Rao et al. 2000) because of the fact that even the original
waste, before precipitation, would contain less than a ppm even though the
radioactivity would be high.
8.4.5 Membrane Contactors
Unlike other membrane processes which are driven by external energy for the
separation, membrane contactors do not need external energy for membrane role
in the separation process. It enables the conventional techniques of separation in
somewhat convenient manner with reference to environment, capacity, and resource
requirements. Membrane contactors are porous barriers. The contactors can exhibit
different functions: filters for the removal of colloids/suspended matter, interphase
contactor in liquid–liquid extraction, absorber for gaseous separation, barrier in
membrane bioreactors, and immobilizer of solvent in supported liquid membrane.
Membrane bioreactors, solvent extraction, gas absorption, and gaseous separation
are some of the examples where membrane contactors have been used. With
reference to water treatment, membrane bioreactors play a very critical role both in
the industrial and domestic wastewater treatments. Membrane solvent extraction is a
developing process which can help in recovering the organics or heavy metal species
from effluents.
Membrane Bioreactor
A membrane bioreactor combines the activated sludge process with a membrane
separation process. The membrane process could be either microfiltration or ultrafiltration. The membrane acts as a barrier filter which enables it to hold the microorganisms and allow the transport of nutrients, oxygen, and degradation products
8 Role of Membranes in Wastewater Treatment
269
additives would be very small,
4. Ultrafiltraton is backwashable, and hence the complex can be recovered as such in
a backwash cycle.
5. Further, most of the complexation or adsorption processes are sensitive to
pH. Hence, after size enhancement and separation of heavy ions, the size
enhancement can be reversed by altering pH or other conditions, enabling the
separation and recovery of metal ion species as well as the complex for reuse.
Removal of copper, nickel, and chromium has been extensively studied using
a variety of complexing agents such as polyethylenimine (Sarkar et al. 2013;
Kadioglu et al. 2010), carboxymethyl cellulose (Kavitha et al. 2018), and
chitosan derivative (Kavitha et al. 2019). The removal of cesium and strontium,
the radioactive contaminants of nuclear waste from the supernatant solution (after
cesium was co-precipitated along with copper ferrocyanide and strontium as
phosphate), indicated that size-enhanced ultrafiltration can be used as a last
mile separation process (Rao et al. 2000) because of the fact that even the original
waste, before precipitation, would contain less than a ppm even though the
radioactivity would be high.
8.4.5 Membrane Contactors
Unlike other membrane processes which are driven by external energy for the
separation, membrane contactors do not need external energy for membrane role
in the separation process. It enables the conventional techniques of separation in
somewhat convenient manner with reference to environment, capacity, and resource
requirements. Membrane contactors are porous barriers. The contactors can exhibit
different functions: filters for the removal of colloids/suspended matter, interphase
contactor in liquid–liquid extraction, absorber for gaseous separation, barrier in
membrane bioreactors, and immobilizer of solvent in supported liquid membrane.
Membrane bioreactors, solvent extraction, gas absorption, and gaseous separation
are some of the examples where membrane contactors have been used. With
reference to water treatment, membrane bioreactors play a very critical role both in
the industrial and domestic wastewater treatments. Membrane solvent extraction is a
developing process which can help in recovering the organics or heavy metal species
from effluents.
Membrane Bioreactor
A membrane bioreactor combines the activated sludge process with a membrane
separation process. The membrane process could be either microfiltration or ultrafiltration. The membrane acts as a barrier filter which enables it to hold the microorganisms and allow the transport of nutrients, oxygen, and degradation products
8 Role of Membranes in Wastewater Treatment
269