Science and Technology Journal,
Vol. 3
Issue: 1
ISSN: 2321-3388
Remediation of TNT and RDX from Ground Water using BiocharAlginate beads by in-situ and ex-situ Column Reactors Worked on Siphon Principle Hoon Roh1, Lakshmi Prasanna Lingamdinne1, Yu-Lim Choi1, Janardhan Reddy Koduru2, Yoon-Young Chang1 and Jae-Kyu Yang3,* 1
E-mail: *
[email protected] Abstract—
biochar-alginate beads (ATLB-AB) were used for the treatment of TNT ground water. In order to study the practical applicability of ATLB-AB in a large scale waste
R2 and TNT (R (KTh
2
Keywords: Biochar beads,
INTRODUCTION unds (Fig. 1), may enter into the environment during military and industrial applications. These activities would lead to a serious pollution problem
drinking water [1]. strong demands for clean up these contaminants using costeffective technologies.
including
munitions and their discharge into environment resulting in contamination of groundwater, surface water, marine, and terrestrial environments. The USEPA has proposed a
Fig. 1: Structure of Explosive Compounds, TNT, HMX and RDX
Remediation of TNT and RDX from Ground Water Among the various conventional water-treatment
at 700°C, by typical procedure reported in our previous research paper [10]. The prepared biochar-alginate beads
the removal of environmental pollutants due to its high column studies in the present study. and cost effectiveness. The biomass of plant materials
EXPERIMENTAL METHODS use of biomass material can cause undesired problems due overcome the associated problems of biomass and in search for new treatment technologies, biochar prepared under heat treatment conditions can be an effective approach for the adsorption of environmental pollutants. o
material produced from the varieties of biomass by pyrolysis [4], which is a carbonization process in which the content of carbon increases with temperature accompanied by a
C. All
Several studies have been reported for removing metals
(ATL) biochar powder has been used for the [8, 9]. adsorbent materials in large scale waste water treatment, there is a need to focus on the preparation of low-cost and eco-friendly adsorbents for facile and effective removal of pollutants in wastewaters. Considering the above factors, biochar-alginate beads (ATLB-AB) were prepared using (ATL) biochar pyrolysis
Shredding and Pyrolysis
Web Beads Fig. 2: Schematic Representation of
Preparation of ATLB-AB beads was carried out by our previous reported procedure [10]. In the typical procedure, the biomass, was air-dried at room temperature. Biomass was then placed in ceramic
(Thermolyne 48000). The pyrolysis temperature was raised to the selected values of 700o 10o
Biochar
Prepared Beads
33
Bead Manufacturing Equipment
Nozzles Preparation
biochar samples were allowed to cool to room temperature %) was incorporated with sodium alginate
allowed to harden for 1 hr and rinsed with deionized water and then dried at room temperature. The visual images of buffalo weed raw (ATL), biochar (ATLB) and biochar alginate beads (ATLB-AB) and schematic representation
ATLB-AB
reactor that stimulate real sites. Then the groundwater was constant groundwater level was maintained in the semithe reactor packed with bio-beads using a pump. After
was measured by siphon principle. The concentrations of
for the column reactor are summarized in Table 1. The upwards from a reservoir or ground in the lower regions and over a barrier and then down to lower level with the
reactor. Table 1: Design Parameters for the in-situ Column Reactor Packed with ATLB-AB
rate by utilizing the natural hydraulic head difference between two points. The permeable treatment media can
Parameters Amount Pore volume Porosity Apparent density
ATLB-AB 11.5 kg
Field Soil 96.4 kg
0.5
0.4
or permanent. It was applicable to any contaminant, but it
ATLB-AB depends on the velocity of the water and diameter of the pipe. So for applying the siphon principle needs to optimize the contaminated groundwater was continuously circulated maintained constant in the semi-circular reactor. After turn-on the pump, ground water was initially introduced inside was certain to be positive in the groundwater level range. After turn on the pump, ground water was initially introduced in the reactor and then allowed the water could
continuously by siphon principle. When continuous water
well was passed through the reactor (15 cm diameter and 70 cm height) packed with ATLB-AB. The concentration of outlet (top) position of the column reactor as a function of
34
Remediation of TNT and RDX from Ground Water
the breakthrough curves and to determine the column characteristics. Table 2: Design Parameters for the ex-situ Column Reactor Packed with ATLB-AB Parameters Packed amount of ATLB-AB Pore volume Porosity
Conditions 5.8 kg 6.18 L 0.5
RESULTS AND DISCUSSION
The physical and chemical characterization of biocharalginate beads were discussed in our previous paper [10].
in Brunauer, Emmett and Teller (BET) method, which was higher than calcium alginate beads surface area [8, 9], which may due to calcium and sodium ions are coated SEM (SEC, Nano eye SNE-1500 M) morphology of ATLB-AB (Fig. 4(a)) [10] where the morphology was different with bare biochar. The pore diameter of the obtained biocharUnion of Pure and Applied Chemistry (IUPAC)), which was
Siphon Set-up
discussed in our previous reports [10].
reported in our previous reports (Fig. 4(b)) [10], indicated 0
represents a low pattern in 0
0
suggest formation of turbostratic carbon crystallites
Fig. 3: (a) Total Experimental Set-Up of Simulated Underground Model of the Ex–Situ Filtration System Packed Sand and Field Soil and (B) Closed View of Underground Model Ex-Situ Column Reactor Experimental Set-Up. The White Circle Indicates Sampling Points
beads were well used as sorbent.
-1
) stretching vibrations
from adjacent hydrogen in biochar-alginate beads. It also -1 -1
-1
-1
) groups,
indicating the presence of aromatic carbonyls or ethers or curves were plotted between ratio of outlet (top) and initial concentration of adsorbates (C/C C/Co) vs vs time (hr). Thomas 35
AB was good adsorbent.
(a)
(b)
(c) Fig. 4: SEM Morphology of Biochar (ATLB)/ Biochar-alginate Beads(ATLB-AB) (a), X-ray Diffraction Pattern (b) and FT-IR Spectrum of Biochar-alginate Beads (ATLB-AB) (c)
36
Remediation of TNT and RDX from Ground Water
st, the water level in the semi-circular reactor packed ) was maintained at a constant level. Then groundwater was introduced in the reactor using a pump. After identifying the introduction of water, pump was the reactor was measured by siphon principle. 1200
siphon tube on the discharged amount of water was studied.
1000
Four tubes having different diameter such as 4, 6, 8 and 10
800
mm were used and the discharged amount of groundwater
600
(b)
400 200
groundwater was decreased as the pipe diameter of siphon decreased. Since the discharged amount of groundwater was greatly decreased with 4 mm diameter tube at any slope, the diameter of siphon should be at least 4 mm. The discharged amount of ground water was linearly correlated frictional force as the pipe diameter of siphon decreased as well as the decreased discharge amount of groundwater
0 0.00
0.05
0.10
0.15
0.20
Hydraulic gradient
Fig. 5: Variation of Discharged Amount of Water at Different Slope and Pipe Diameter of Siphon (Soil: Joomoonjin Sand) (a) and a Linear Correlation Between Discharge Amount of Groundwater and Variation of Hydraulic Grade (dh/dl), y = 5638.6x, r2 = 0.963 (b)
at low slope due to a low hydraulic gradient (dh/dl) (Fig. 5(b)). As the ground water was discharged from soil by siphon principle, ground water level was varied initially and then reached to a constant level. Thus discharged amount of ground water at all conditions was linearly well correlated with hydraulic gradient (dh/dl) (r result suggests a constant hydraulic conductivity in soil
instead of Joomoonjin sand was packed into the same reactor used previously. Then groundwater was initially
(Joomoonjin sand). Table 3: Variation of Discharged Amount of Water at Different Slope and Pipe Diameter of Siphon (Soil: Joomoonjin Sand) Slope 18°
45°
4 mm 54 54 54 55
Flow Rate (ml/min) 6 mm 8 mm 440 480 400 500 540
10 mm 700 800 1,000
37
rate of discharged water from the reactor was measured by diameter of siphon on the discharged amount of water was studied. Four pipes having different diameters such as 4, 6, 8 and 10 mm were used (Fig. 6 (a)) and the discharged amount of groundwater was measured at four different o (Table 4). The discharged
soil was not much different with that from the reactor packed with Joomoonjin sand. Discharged amount of groundwater
1200 1000
of the discharged amount of groundwater from the reactor
(b)
800
that from the reactor packed with Joomoonjin sand. This result indicates that pipe diameter is a major factor affecting discharged amount of groundwater. This trend was obviously observed when soils having low hydraulic conductivity were
600 400 200 0 0.0
soil has three times low hydraulic conductivity compared to Joomoonjin soil, indicating increased resistance. This result clearly suggests that discharged amount of groundwater by siphon is greatly affected by the resistance of pipe than the slope of pipe. As the pipe diameter decreased, resistance decreased, hydraulic grade decreased, causing decreased discharged amount of groundwater. When groundwater was discharged by siphon principle, groundwater level was varied initially and then reached to a constant level at steady state. Considering the discharged amount of ground water at all conditions, a good linear correlation (Fig. 6 (b)) (r (dh/dl) and discharged amount of ground water. It means that hydraulic conductivity of soil (Joomoonjin sand) was constant.
0.2
0.4
0.6
0.8
Hydraulic gradient
Fig. 6: Variation of Discharged Amount of Groundwater at Different Slope and Pipe Diameter (Soil: Field Soil Near Shooting Range) (a) and a Linear Correlation between Hydraulic Grade (dh/dl) and Discharged Amount of Groundwater (y=1638x, r2=0.8462) (b)
bed in-situ column reactor, Thomas model and bed depth service time (BDST) model were applied. Thomas model is a dynamic model used to describe adsorption process in the
applied to favorable and unfavorable adsorption isotherm. Table 4: Variation of Discharged amount of Groundwater at Different Slope and Pipe Diameter (Soil: Field Soil Near Shooting Range) Slope 18°
45°
4 mm Flow Rate (ml/min) 46 47 50 55
6 mm Flow Rate (ml/min)
400
8 mm Flow Rate (ml/min) 680 700 740
size and adsorbent amount considering concentration of diffusion limitation is not described in this model. A linear
10 mm Flow Rate (ml/min)
940 960 1,000
In
co c
kTh
qo M
k T h cov
(1)
where, C0 and C adsorbate at inlet and outlet, respectively. kTh a Thomas rate constant. Q q0 M (g), V M V (L) is
volume, respectively. kTh and q0 can be calculated from the slope of ln[(C C0/C)-1] vs V (Fig. 7). A major limitation for the V Thomas model is that it is based on the second-order kinetics and assume that adsorption is not limited in chemical reaction as well as mobility of interference is controlled. and regression results are shown in Table 5. Breakthrough The q0 lower than that observed in the small column reactor which
38
Remediation of TNT and RDX from Ground Water was reported elsewhere [10]. Table 5: Regression Results of Thomas Model for the B Reactor Flow rate (ml/min) 50
C0 (mg/l)
KTh (m3/g.h) 0.0045
q0 (mg/kg)
TNT
r2 0.7454
(a)
Groundwater Fig. 9 (b)), concentration at initial
(b)
(a) Fig. 7: Breakthrough of TNT (a) and RDX (b) from in-situ Column System Packed with ATLB-AB (a Line Represents Model Prediction)
(b)
Fig. 9: Variation of TNT (a) and RDX (b) Concentration at Different Sampling Point of the ex-situ Column Reactor
middle and outlet point.
39
ACKNOWLEDGEMENT packe This investigation was supported by Korea Ministry of reason for this trend may be different removal pattern of system, discharged groundwater from soil layer can Kwangwoon University, Seoul, South Korea
REFERENCES 1. stu Bunluesin, S., Kruatrachue, M., Pokethitiyook, P., Upatham,
CONCLUSION 1. The applicability of prepared and characterized ATLB-AB was evaluated by developing of in-situ and
temperature and inorganic matter on combustion
4.
siphon principle was well optimized by studying at
5. derived biochar effectively sorbs lead and atrazine. Environ.
The in-situ laboratory scale column adsorption of
6.
7. 1-naphthol by biochars of orange peels with different
R2
8.
(R2
biochar for cadmium (II) and lead (II) adsorption in single
and Thomas constants (KTh) were 0.0045 and 9.
4. 10.
by biochar-beads. Biochar-beads can be well 11.
5. column reactor was higher than that by in-situ column reactor.
40
Remediation of TNT and RDX from Ground Water 16. fungal biomass. Biochem. Eng. J. 8(1): 51-59. 17. 14. waste ‘wheat bran’ for the biosorptive remediation of
Surface functionality and carbon structures in lignocellulosic-derived biochars produced by fast pyrolysis
15. violet by Artocarpus heterophyllus (jackfruit) leaf powder.
BIOGRAPHY Professor Jae-Kyu Yang
remediation of surface and groundwater as well as development of new adsorbent and reactive materials. and national conferences.
41
