some of them have been summarized with the results published in scientific journals
(see Table 2.5). In most cases, nanoparticles were prepared directly on site using
reduction of ferric salt by borohydride and only small amount of nZVI (less than
20 kg) was applied. The researchers focused not only on the remediation efficiency
of nanoparticles (Glazier et al. 2003; Bennett et al. 2010; Chowdhury et al. 2015) but
also on their migration ability and influence on microbial communities (Bennett et al.
2010; Kocur et al. 2014, 2015).
A pilot-scale application of nZVI in Marine Corps Depot former dry cleaners on
Parris Island, South Carolina, was unique by its scale among other published pilot
tests. Total amount of 275 kg of RNIP nZVI was emulsified with corn oil and
surfactant in order to enhance its mobility in the subsurface. The emulsion was
applied deploying two methods—pneumatic injection and direct injection. The
authors described the effects of nZVI on CHCs levels in the first paper (Su et al.
2012), and transport and transformation of the nanoparticles in the second one
(Su et al. 2013).
The use of nZVI for Cr(VI) reduction in a pilot in situ remediation was recently
reported (Němeček et al. 2015). The polluted site is located in the northern part of the
Czech Republic where potassium dichromate spread from the leather processing
plant. Prior to the treatment of the site, the Cr(VI) concentration in the soil,
accounting for up to 46 mg/kg, prevailed over those in the groundwater (3 mg/L).
The contaminated aquifer is situated in the quaternary sands and gravels with clayey
admixtures and the water table was found 4.5–5.5 m bgl (aquifer thickness about
5 m). The groundwater flows with a velocity 0.2–2 m per day and discharges into a
river 500 m away. In August 2012, 120 kg of nZVI (NANOFER 25 from NANO
IRON s.r.o., Czech Republic) was applied to the saturated contaminated zone
through three injection wells situated perpendicularly to the groundwater flow with
spacing of 2.8 m (i.e., configuration of the injected geochemical barrier). Another
four monitoring wells (1 of them up-gradient and 3 down-gradient) has been drilled
at the site and the evolution of selected physico-chemical parameters and changes in
Cr(VI) contamination level were monitored before and after the nZVI. The nZVI
application resulted in an immediate decrease in the redox potential down to
À484 mV (within 1 day), followed by a rapid decrease in the concentration of
both Cr(VI) and total Cr. The rapid reductive effect of nZVI was observed at a
distance of 7 m down-gradient.
A similar approach, which seems to be highly promising due to the partial
regeneration of the applied nZVI through successive abiotic and biotic reduction
steps, was applied by the same authors at another site in the Czech Republic
(Němeček et al. 2016). In this case, the aquifer is located in quaternary sandy gravel
with silty admixtures and overlaid by clay and clayey loam. It is approx. 4 m thick
and drained by the groundwater flow equal to 1.5 m per day into a river at the
distance of 430 m. The groundwater was contaminated with Cr(VI) (4–57 mg/L) and
TCE/cis-DCE (400–6000 μg/L of sum of CHCs) as a consequence of the historical
chromium coating industrial activities. Two types of nZVI particles (20 kg of
NANOFER STAR followed by another 20 kg of NANOFER 25S, both from
NANO IRON s.r.o., Czech Republic) were applied by direct push technology during
40
T. Phenrat et al.
(see Table 2.5). In most cases, nanoparticles were prepared directly on site using
reduction of ferric salt by borohydride and only small amount of nZVI (less than
20 kg) was applied. The researchers focused not only on the remediation efficiency
of nanoparticles (Glazier et al. 2003; Bennett et al. 2010; Chowdhury et al. 2015) but
also on their migration ability and influence on microbial communities (Bennett et al.
2010; Kocur et al. 2014, 2015).
A pilot-scale application of nZVI in Marine Corps Depot former dry cleaners on
Parris Island, South Carolina, was unique by its scale among other published pilot
tests. Total amount of 275 kg of RNIP nZVI was emulsified with corn oil and
surfactant in order to enhance its mobility in the subsurface. The emulsion was
applied deploying two methods—pneumatic injection and direct injection. The
authors described the effects of nZVI on CHCs levels in the first paper (Su et al.
2012), and transport and transformation of the nanoparticles in the second one
(Su et al. 2013).
The use of nZVI for Cr(VI) reduction in a pilot in situ remediation was recently
reported (Němeček et al. 2015). The polluted site is located in the northern part of the
Czech Republic where potassium dichromate spread from the leather processing
plant. Prior to the treatment of the site, the Cr(VI) concentration in the soil,
accounting for up to 46 mg/kg, prevailed over those in the groundwater (3 mg/L).
The contaminated aquifer is situated in the quaternary sands and gravels with clayey
admixtures and the water table was found 4.5–5.5 m bgl (aquifer thickness about
5 m). The groundwater flows with a velocity 0.2–2 m per day and discharges into a
river 500 m away. In August 2012, 120 kg of nZVI (NANOFER 25 from NANO
IRON s.r.o., Czech Republic) was applied to the saturated contaminated zone
through three injection wells situated perpendicularly to the groundwater flow with
spacing of 2.8 m (i.e., configuration of the injected geochemical barrier). Another
four monitoring wells (1 of them up-gradient and 3 down-gradient) has been drilled
at the site and the evolution of selected physico-chemical parameters and changes in
Cr(VI) contamination level were monitored before and after the nZVI. The nZVI
application resulted in an immediate decrease in the redox potential down to
À484 mV (within 1 day), followed by a rapid decrease in the concentration of
both Cr(VI) and total Cr. The rapid reductive effect of nZVI was observed at a
distance of 7 m down-gradient.
A similar approach, which seems to be highly promising due to the partial
regeneration of the applied nZVI through successive abiotic and biotic reduction
steps, was applied by the same authors at another site in the Czech Republic
(Němeček et al. 2016). In this case, the aquifer is located in quaternary sandy gravel
with silty admixtures and overlaid by clay and clayey loam. It is approx. 4 m thick
and drained by the groundwater flow equal to 1.5 m per day into a river at the
distance of 430 m. The groundwater was contaminated with Cr(VI) (4–57 mg/L) and
TCE/cis-DCE (400–6000 μg/L of sum of CHCs) as a consequence of the historical
chromium coating industrial activities. Two types of nZVI particles (20 kg of
NANOFER STAR followed by another 20 kg of NANOFER 25S, both from
NANO IRON s.r.o., Czech Republic) were applied by direct push technology during
40
T. Phenrat et al.