“ Federico II ”
Department of Hydraulic, Geotechnical and Environmental Engineering
Stevens Institute of Technology
Center for Environmental Systems
Master thesis in Environmental Engineering ABSTRACT
Removal of organic contaminants using zero valent iron: treatment of wastewaters from Insensitive
Munitions Explosives (IMX) manufacture
Supervisors : Author :
Prof. Massimiliano Fabbricino Amalia Terracciano Prof. Xiaoguang Meng Matr. M 67/59
Academic Year 2012/2013
1 ABSTRACT
The aim of the present work was to study the applicability of Zero-Valent Iron (Fe0) to treat wastewater produced by Insesitive Munition Explosives (IMX) manufacture. The study included batch tests, column tests and field tests aimed at investigating the potentiality of the treatment for NTO, NQ, DNAN and RDX removal, mainly focalized on process optimization in terms of operative conditions. The last part of the study was dedicated, instead, to the evaluation of best options for iron removal from treated wastewater.
Results of batch tests are summarized in Figures 3.1-3.4.
0 200 400 600 800 1000 1200 1400
0 20 40 60 80
NTO (ppm)
Time (min)
PH=3 pH=4 pH=5 pH=3
0 100 200 300 400 500 600 700
0 20 40 60 80
N Q ( pp m )
Time (min
)
PH=3 pH=4 pH=5 pH=3
Fig 3.1 NTO concentration vs time for Batch 1,2,3
0 20 40 60 80 100
0 20 40 60 80
R D X ( pp m )
Time (min)
PH=3 pH=4 pH=5 pH=3
Fig 3.2 NQ concentration vs time for Batch 1,2,3
Fig 3.3 RDX concentration vs time for Batch 1,2,3
0 50 100 150 200 250 300
0 20 40 60 80
D N A N ( pp m )
Time (min)
PH=3 pH=4 pH=5 pH=3
Fig 3.4 DNAN concentration vs time for Batch 1,2,3
2
0 2 4 6 8
0 200 400 600 800 1000 1200
0 100 200 300
Effluent pH
IM X ( pp m )
Time(h)
NTO NQ
DNAN RDX
pH
As showed, DNAN, RDX and NTO were easily removed at pH 3 even if the reaction rate was different for the three compounds: the degradation of NTO was clearly more rapid than the degradation of RDX and DNAN, whose removal was not reached within one hour. On the contrary NQ was only partially removed: the reaction rate was more rapid for pH 3 than pH 4 and 5, but in all cases the percentage of degradation was below 60%.
Column tests confirmed some of the previous results, and allowed to individuate the principal operative parameters to be used for full scale applications.
0 2 4 6 8
0 200 400 600 800 1000 1200
0 25 50 75 100
Effluent pH
IM X ( pp m )
Time(h)
NTO pH
0 2 4 6 8
0 200 400 600 800 1000 1200
0 20 40 60 80
Effluent pH
IM X ( pp m )
Time(h)
NTO pH
0 2 4 6 8
0 200 400 600 800 1000 1200
0 100 200 300
Effluent pH
IM X ( pp m )
Time(h)
NTO NQ
DNAN RDX pH
0 2 4 6 8
0 200 400 600 800 1000 1200
0 100 200 300
Effluent pH
IM X ( pp m )
Time(h)
NTO NQ
DNAN RDX pH
Fig 3.5 Column 1, NTO and effluent pH vs time Fig 3.6 Column 2, NTO and effluent pH vs time
Fig 3.7 Column 3, IMX and pH effluent vs time Fig 3.9 Column 4, IMX and pH effluent vs time
3
0 2 4 6 8
0 200 400 600 800 1000 1200
15 65 115 165 215
Effluent pH
IM X ( pp m )
Time(h)
NTO NQ
DNAN RDX pH
As it can be deduced from Figures 3.5-3.10 the ZVI showed a good efficiency in terms of NTO, DNAN and RDX removal, with an EBCT of 1 hour. NQ removal was once more limited.
Field test was characterized by varying values of EBCT and influent pH value (Figures 3.13 and 3.14).
Obtained results were used to repeat lab test to optimize process performances (Figures 3.16-3.23).
Fig 3.10 Column 5, IMX and pH effluent vs time
0 1 2 3 4 5 6
0 100 200 300 400 500 600 700
0 50 100 150 200
E B C T (h)
IMX (ppm)
Time(h)
NTO NQ
RDX DNAN
EBCT
2.5 2.7 2.9 3.1 3.3 3.5
0 100 200 300 400 500 600 700
0 50 100 150 200
R aw pH
IM X ( pp m )
Time(h)
NTO NQ
RDX DNAN PH Raw
Fig 3.13 Field Column, IMX and EBCT vs time Fig 3.14 Field Column, IMX and Raw pH vs time
4
2 3 4 5 6 7 8
0 100 200 300 400 500 600 700
20 40 60 80 100 120
Effluent pH
IMX (ppm)
Time (h)
First stage NTO NQ
RDX DNAN
PH
2 3 4 5 6 7
0 50 100 150 200 250 300 350 400 450 500
0 20 40 60 80 100 120 140 160
Effluent pH
IMX (ppm)
Time (h)
NTO NQ
RDX DNAN
PH
2 3 4 5 6 7 8
0 100 200 300 400 500 600 700
20 40 60 80 100 120
Effluent pH
IMX (ppm)
Time (h)
Second Stage NTO NQ
RDX DNAN
PH
2 3 4 5 6 7
0 50 100 150 200 250 300 350 400 450 500
0 50 100 150 200 250 300 350 400 450
Effluent pH
IMX (ppm)
Time (h)
NTO NQ
RDX DNAN
PH
2 3 4 5 6 7
0 50 100 150 200 250 300 350 400 450 500
13.5 33.5 53.5 73.5
Effluent pH
IMX (ppm)
Time (h)
NTO NQ RDX DNAN PH
2 3 4 5 6 7
0 50 100 150 200 250 300 350 400 450 500
0 150 300 450 600 750
Effluent pH
IMX (ppm)
Time (h)
NTO NQ
RDX DNAN
PH
Fig 3.16 First stage column, IMX and effluent pH vs time Fig 3.17 Second stage column, IMX and effluent pH vs time
Fig 3.18 Column 1(i) , IMX and effluent pH vs time Fig 3.19 Column 2(i) , IMX and effluent pH vs time
Fig 3.20 Column 3(i) , IMX and effluent pH vs time Fig 3.21 Column 4(i), IMX and effluent pH vs time
5
2 3 4 5 6 7
0 50 100 150 200 250 300 350 400 450 500
0 20 40 60 80 100 120 140 160 180 200 220
Effluent pH
IMX(ppm)
Time (h)
NTO NQ
RDX DNAN
PH
2 3 4 5 6 7 8
0 50 100 150 200 250 300 350 400 450 500
10 30 50 70 90 110 130 150 170 190 210
Effluent pH
IMX (ppm)
Time (h)
NTO NQ
RDX DNAN
pH
Results of iron removal tests are finally reported in Figures(3.24-3.26). Aeration (Test A) showed a very low efficiency for iron removal. The water had a light clarity after the treatment, but still a heavy red color, index of a high concentration of ferric ions (Fe
3+). Combined use of calcium oxide and aeration (Test B) allowed to improved the final efficiency. The samples showed a greater clarity after the treatment but the color was still yellow, sign of a significant persistency of soluble iron. Final oxidation with Sodium Hypochlorite (Test C) allowed to obtain a good removal of iron.
Fig 3.22 Column 5(i), IMX and effluent pH vs time Fig 3.23 Column 6(i), IMX and effluent pH vs time
Fig 3.24 Test A, aeration treatment Fig 3.25 Test B, Calcium Oxide Fig 3.26 Test C, NaClO
6
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
0.5 1 1.5 2 2.5 3
Soluble Iron Conc(ppm)
Sodium Hypochlorite dosage (ml)
