Geoscience Reference
In-Depth Information
MOBILE PHASE
Na
+
, K
+
, Ca
2+
, Mg
2+
,
Mn
2+
, Fe
2+
, Cl
-
, O
2
,
NO
3
-
, CH
2
O
MATRIX PHASE
MnO
2
, Fe(OH)
3
,
SOLID PHASE
Na
+
, K
+
, Ca
2+
,
Mg
2+
, Mn
2+
, Fe
2+
BIO PHASE
X1, X2, X3, O
2
, NO
3
-
,
Mn
2+
, Fe
2+
, CH
2
O,
MnO
2
, Fe(OH)
3
Fig. 1.
Conceptual model.
The one-dimensional mass transport equation is represented by Eq. (1)
when the
y
-coordinate is taken along the depth of the experimental
apparatus.
θ
w
D
L
∂
[
C
i
]
∂y
+
S
i
,
∂
[
C
i
]
∂t
∂
[
C
i
]
∂y
1
θ
w
∂
∂y
+
v
=
(1)
where
θ
w
is the water content,
v
the pore velocity, and
D
L
is the lon-
gitudinal dispersion coecient that is calculated by the product of the
longitudinal dispersion length and the pore velocity.
Following equations represent the Fe
2+
concentration change in each
phase.
Mobile phase
d[Fe
2+
]
mob
d
t
∂
[Fe
2+
]
mob
∂t
∂
[Fe
2+
]
mob
∂y
Fe
2+
:
+
v
=
θ
w
D
L
∂
[Fe
2+
]
mob
∂y
+
T
b
(1
1
θ
w
∂
∂y
−
n
)
=
a
θ
bio
√
D
L
θ
bio
+
θ
w
([Fe
2+
]
bio
−
[Fe
2+
]
mob
)+
S
3
Fe
,
·
(2)
Solid phase
∂
∂t
(
θ
w
[Fe
2+
]
im
)=
Fe
2+
:
−
θ
w
S
3
Fe
(3)
(1
−
n
)
ρ
s
θ
w
[Fe
2+
]
im
=
m
Fe
.
(4)
