removal and compactness, the absence of chemical additives and relatively low
energy costs (He and Jiang 2008). In fact, despite low driving pressures, the major
part of the energy consumed is used to maintain a high cross-flow velocity in order to
prevent clogging and concentration polarization (IAEA 2004). In turn, this high
velocity allows a very simple design for the treatment train (Sect. 1.5). Typically,
less than 10% of the filtered volumes are needed for membrane cleaning operations
(Degrémont 2005). Irreversible membrane clogging is reduced by using more or less
aggressive chemicals such as acids, bases, oxidizing agents, which should be
cautiously used (Rabuni et al. 2015). For the hydrophobic solutes in micelles or
microemulsions separation, the rejection rates for contaminants in the range 85–99%
are maintained all over the range of surfactant concentrations, thanks to adsorption
and sieving effect at low and higher concentrations, respectively (Chakrabarty et al.
2010). In contrast, recovery rates for surfactants in filtrates is very dependent on their
concentration, solute–membrane and solute–solute interactions (Hanafiah et al.
2018), ranging from about 100% at C S lower than the CMC for hydrophilic
membranes to few percents for highly concentrated wastewater (Azoug et al.
1998; Jönsson et al. 2006). UF of contaminated GW during surfactant soil-flushing
operations carried out using surfactant concentrations lower than the CMC was
investigated for PCBs (Ang and Abdul 1994) and BTEX removal (Sabatini et al.
1998). Surfactant-recovery yields in the range 46–80% were reported. In the latter
case, pervaporation was used first in order to remove the volatile contaminants from
the contaminated GW, while UF was dedicated to surfactant reconcentration before
reinjection. UF has also been successfully tested for the recovery of cyclodextrins
from PAHs-contaminated soil leachates using colza oil microemulsions for the PAH
retention (Petitgirard et al. 2009). Despite ultrafiltration being widely investigated
for the removal of ions and chelated metal using micellar enhanced ultrafiltration
(MEUF) for example (Baek et al. 2003; Jung et al. 2008; Rivas et al. 2011; El
Zeftawy and Mulligan 2011), few studies have been reported for the treatment of
metal complexes-contaminated wastewater with ligand recovery (Zamariotto et al.
2010).
1.4.2 Physicochemical Treatments
1.4.2.1 Sorption
Sorption is a physicochemical process in which a solute becomes attached to a solid.
Many materials have been proposed as sorbents, mostly because of their high
specific surface area. Well-known sorbents are activated carbon, resins, iron
oxyhydroxides, zeolites, but there are many others like biopolymers (e.g., cotton)
and waste materials since costs for production and regeneration is a critical parameter. There is a variety of processes through which sorption occurs, e.g., ion
exchange, adsorption, absorption, and complexation. The regeneration pathway of
sorbents depends on the physicochemical properties of the bound contaminant.
36
N. Fatin-Rouge
energy costs (He and Jiang 2008). In fact, despite low driving pressures, the major
part of the energy consumed is used to maintain a high cross-flow velocity in order to
prevent clogging and concentration polarization (IAEA 2004). In turn, this high
velocity allows a very simple design for the treatment train (Sect. 1.5). Typically,
less than 10% of the filtered volumes are needed for membrane cleaning operations
(Degrémont 2005). Irreversible membrane clogging is reduced by using more or less
aggressive chemicals such as acids, bases, oxidizing agents, which should be
cautiously used (Rabuni et al. 2015). For the hydrophobic solutes in micelles or
microemulsions separation, the rejection rates for contaminants in the range 85–99%
are maintained all over the range of surfactant concentrations, thanks to adsorption
and sieving effect at low and higher concentrations, respectively (Chakrabarty et al.
2010). In contrast, recovery rates for surfactants in filtrates is very dependent on their
concentration, solute–membrane and solute–solute interactions (Hanafiah et al.
2018), ranging from about 100% at C S lower than the CMC for hydrophilic
membranes to few percents for highly concentrated wastewater (Azoug et al.
1998; Jönsson et al. 2006). UF of contaminated GW during surfactant soil-flushing
operations carried out using surfactant concentrations lower than the CMC was
investigated for PCBs (Ang and Abdul 1994) and BTEX removal (Sabatini et al.
1998). Surfactant-recovery yields in the range 46–80% were reported. In the latter
case, pervaporation was used first in order to remove the volatile contaminants from
the contaminated GW, while UF was dedicated to surfactant reconcentration before
reinjection. UF has also been successfully tested for the recovery of cyclodextrins
from PAHs-contaminated soil leachates using colza oil microemulsions for the PAH
retention (Petitgirard et al. 2009). Despite ultrafiltration being widely investigated
for the removal of ions and chelated metal using micellar enhanced ultrafiltration
(MEUF) for example (Baek et al. 2003; Jung et al. 2008; Rivas et al. 2011; El
Zeftawy and Mulligan 2011), few studies have been reported for the treatment of
metal complexes-contaminated wastewater with ligand recovery (Zamariotto et al.
2010).
1.4.2 Physicochemical Treatments
1.4.2.1 Sorption
Sorption is a physicochemical process in which a solute becomes attached to a solid.
Many materials have been proposed as sorbents, mostly because of their high
specific surface area. Well-known sorbents are activated carbon, resins, iron
oxyhydroxides, zeolites, but there are many others like biopolymers (e.g., cotton)
and waste materials since costs for production and regeneration is a critical parameter. There is a variety of processes through which sorption occurs, e.g., ion
exchange, adsorption, absorption, and complexation. The regeneration pathway of
sorbents depends on the physicochemical properties of the bound contaminant.
36
N. Fatin-Rouge