and 99.9%, and that TPH in filtrates was approximately 0.9 mg l
À1 , it must be
highlighted that only 3.5 g of hydrocarbons were reinjected into the treated soil with
the reused solutions.
On average the volumetric flux of filtrate was 170 m
3 h
À1 (80% of that for pure
water) and a volume reduction factor of about ten was reached before discharging the
concentrates. The latter can be recycled as substitute fuel for cement production,
because their HHV were about 34000 MJ ton
À1 . The highly biodegradable filtrates
were treated in the municipal sewage treatment plant, since the COD value was too
high for a direct release into the natural environment. Thanks to this strategy, 10% of
costs for chemicals and water were saved. However, they amounted only 6% of the
operational costs. The energy cost represented between 2 and 50% of the chemical
costs (depending on whether electricity or gasoline was used as energy sources) and
was mainly dedicated to operate the wastewater treatment. Finally, it must be
emphasized that the amount of surfactant lost in soil, nature, and concentration of
compounds in the wastewater, and the hydrophilic character of the UF membrane
play critical roles in surfactant recovery (Hanafiah et al. 2018). This highlights the
importance of detailed treatability studies before field works and we think that
surfactant recovery rates can be increased twice through parameters optimization.
1.6 Conclusion and Recommendations
SL deals essentially with hardly degradable or nondegradable as well as low or
nonvolatile compounds. The simultaneous removal of several contaminants is possible (especially for in situ treatments), but it may require the use of expensive
extracting agents and the implementation of complex wastewater treatment technologies. The recovery of the leaching solutions with the aim to reuse them is driven by
environmental, economic, and sustainable considerations. It should involve waste
recycling as much as possible in the form of raw materials suitable for economic
activities, yet in the frame of very restrictive regulations and specifications.
0,0
0,5
1,0
1,5
0
2000
4000
6000
8000
10000
Water
TPH (mg l
-1
)
Surfactant concentration (mg l
-1
)
PV ext
LB
TPH
LB-solution
0
200
400
600
800
1000
Fig. 1.16 Profiles for total
petroleum hydrocarbon
(TPH) extraction and
surfactant recovery in soil
leachates as a function of the
pore volumes extracted
(PV ext ). The different phases
of the soil treatment are
shown by arrows
48
N. Fatin-Rouge
À1 , it must be
highlighted that only 3.5 g of hydrocarbons were reinjected into the treated soil with
the reused solutions.
On average the volumetric flux of filtrate was 170 m
3 h
À1 (80% of that for pure
water) and a volume reduction factor of about ten was reached before discharging the
concentrates. The latter can be recycled as substitute fuel for cement production,
because their HHV were about 34000 MJ ton
À1 . The highly biodegradable filtrates
were treated in the municipal sewage treatment plant, since the COD value was too
high for a direct release into the natural environment. Thanks to this strategy, 10% of
costs for chemicals and water were saved. However, they amounted only 6% of the
operational costs. The energy cost represented between 2 and 50% of the chemical
costs (depending on whether electricity or gasoline was used as energy sources) and
was mainly dedicated to operate the wastewater treatment. Finally, it must be
emphasized that the amount of surfactant lost in soil, nature, and concentration of
compounds in the wastewater, and the hydrophilic character of the UF membrane
play critical roles in surfactant recovery (Hanafiah et al. 2018). This highlights the
importance of detailed treatability studies before field works and we think that
surfactant recovery rates can be increased twice through parameters optimization.
1.6 Conclusion and Recommendations
SL deals essentially with hardly degradable or nondegradable as well as low or
nonvolatile compounds. The simultaneous removal of several contaminants is possible (especially for in situ treatments), but it may require the use of expensive
extracting agents and the implementation of complex wastewater treatment technologies. The recovery of the leaching solutions with the aim to reuse them is driven by
environmental, economic, and sustainable considerations. It should involve waste
recycling as much as possible in the form of raw materials suitable for economic
activities, yet in the frame of very restrictive regulations and specifications.
0,0
0,5
1,0
1,5
0
2000
4000
6000
8000
10000
Water
TPH (mg l
-1
)
Surfactant concentration (mg l
-1
)
PV ext
LB
TPH
LB-solution
0
200
400
600
800
1000
Fig. 1.16 Profiles for total
petroleum hydrocarbon
(TPH) extraction and
surfactant recovery in soil
leachates as a function of the
pore volumes extracted
(PV ext ). The different phases
of the soil treatment are
shown by arrows
48
N. Fatin-Rouge