14.2.4 Pilot Field In Situ Application
For an in situ pilot validation of results obtained from the laboratory tests, an area of
Czech industrial factory aimed at metal production was chosen. Groundwater at this
locality was contaminated mainly with CEs. For the pilot verification of results
employing the in situ approach, the borehole in strongly contaminated area was
chosen. An average level of ΣCEs in this borehole ranged from tens to hundreds
mg/L. The in situ pilot application was carried out in three application rounds from
February to May 2014. The application procedure was as follows:
1st application round (February 27, 2014)
In the first step, 1500 g of commercial ferrates was dissolved in 700 L of distilled
water and the concentrated ferrate solution was applied directly to the application
borehole. The water column in the borehole was subsequently mixed by a submersible pump. In the second step, approximately 1 h after the first injection, the pH in the
borehole was adjusted to ca value 3 by ca 0.5 L of 50% H 2 SO 4 . After this, 15 L of
30% H 2 O 2 was applied and mixed by submersible pump.
2nd and 3rd application round (March 27 and May 13, 2014)
During these next two application rounds, only 15 L of 30% H 2 O 2 was applied.
14.3 Results and Discussion
14.3.1 Results of Laboratory Tests
Groundwater from two different localities (denoted as A and B) was used for the
laboratory tests. Both of these localities were selected also for the subsequent pilot
test. During the laboratory tests, changes in the concentration of priority contaminants, depending on the reaction time and the type of the prepared sample, were
monitored:
• total concentration of CEs (ΣCEs) in the case of locality B (Fig. 14.1)
• total concentration of benzene, toluene, ethylbenzene, and xylenes (ΣBTEX) in
the case of locality B (Fig. 14.2)
The zero point on “Reaction time” axis represent initial values, i.e., values of raw
water before the start of the test. The graphs in Fig. 14.3 show the overall removal
efficiency of the target contaminants after 24 h for each of the prepared samples.
The results obtained from the laboratory tests showed that neither ferrates nor
hydrogen peroxide exhibit significant efficiency in the removal of the targeted
contaminants, in comparison with the blank (sp. 4, 5, and 6). The reason for the
low removal efficiency is high pollution of the tested groundwater, where oxidative
effects of ferrates were consumed by easily oxidizable ballast substances present in
14 Field Study V: Combined Oxidation Technology Using Ferrates (Fe
IV–VI
). . .
321
For an in situ pilot validation of results obtained from the laboratory tests, an area of
Czech industrial factory aimed at metal production was chosen. Groundwater at this
locality was contaminated mainly with CEs. For the pilot verification of results
employing the in situ approach, the borehole in strongly contaminated area was
chosen. An average level of ΣCEs in this borehole ranged from tens to hundreds
mg/L. The in situ pilot application was carried out in three application rounds from
February to May 2014. The application procedure was as follows:
1st application round (February 27, 2014)
In the first step, 1500 g of commercial ferrates was dissolved in 700 L of distilled
water and the concentrated ferrate solution was applied directly to the application
borehole. The water column in the borehole was subsequently mixed by a submersible pump. In the second step, approximately 1 h after the first injection, the pH in the
borehole was adjusted to ca value 3 by ca 0.5 L of 50% H 2 SO 4 . After this, 15 L of
30% H 2 O 2 was applied and mixed by submersible pump.
2nd and 3rd application round (March 27 and May 13, 2014)
During these next two application rounds, only 15 L of 30% H 2 O 2 was applied.
14.3 Results and Discussion
14.3.1 Results of Laboratory Tests
Groundwater from two different localities (denoted as A and B) was used for the
laboratory tests. Both of these localities were selected also for the subsequent pilot
test. During the laboratory tests, changes in the concentration of priority contaminants, depending on the reaction time and the type of the prepared sample, were
monitored:
• total concentration of CEs (ΣCEs) in the case of locality B (Fig. 14.1)
• total concentration of benzene, toluene, ethylbenzene, and xylenes (ΣBTEX) in
the case of locality B (Fig. 14.2)
The zero point on “Reaction time” axis represent initial values, i.e., values of raw
water before the start of the test. The graphs in Fig. 14.3 show the overall removal
efficiency of the target contaminants after 24 h for each of the prepared samples.
The results obtained from the laboratory tests showed that neither ferrates nor
hydrogen peroxide exhibit significant efficiency in the removal of the targeted
contaminants, in comparison with the blank (sp. 4, 5, and 6). The reason for the
low removal efficiency is high pollution of the tested groundwater, where oxidative
effects of ferrates were consumed by easily oxidizable ballast substances present in
14 Field Study V: Combined Oxidation Technology Using Ferrates (Fe
IV–VI
). . .
321