McKay, Donald. "Front matter" Multimedia Environmental Models ...

Table 8.2 Summary of D Value Equations
Advection or flow D = GZ = UAZ G is medium flow rate (m3/h)
and may be given
as a product of velocity U (m/h) and area A m2.
Reaction D = VZk V is volume (m3)
and k is rate constant (h–1).
Diffusion D = BAZ/Y B is molecular or effective diffusivity (m2/h).
A is area (m2)
and Y is path length (m).
Mass transfer D = kAZ k is mass transfer coefficient or velocity (m/h).
Growth dilution D = ZdV/dt = VZk dV/dt is growth rate (m3/h),
and k is the growth
rate constant (h–1)
or (dV/dt)/V.
In all cases, Z refers to the medium in which the process occurs.
The rate is Df (mol/h).
For series processes 1/D = S1/Di.
For parallel processes D = SDi.
Characteristic times are VZ/D (h) where V and Z refer to the source phase.
Half–times are 0.693 VZ/D (h).
Rate constants are D/VZ (h–1).
©2001 CRC Press LLC
KD
= yOC
KOC
L/kg KSW
= KD(
rS/1000)
ZS
= ZWKSW
KOC
can be estimated as 0.41 KOW
(Karickhoff, 1981) or as 0.35 KOW
plus or minus
a factor of 2.5 (Seth et al., 1999). Note that KOM
is typically 0.56 KOC,
i.e., OM is
typically 56% OC. KQA
can be estimated as 6 ¥ 106/PS,
where PS
is the liquid vapor
pressure, or from other correlations using vapor pressure or KOA
as described in
Chapter 5.
8.2 LEVEL I, II, AND III MODELS
These models have been described earlier in Chapters 5, 6, and 7. These programs
are available from http://www.trentu.ca/envmodel in two formats. First are BASIC
models, which can be run directly on DOS systems or using GWBASIC or QBASIC.
Second are more user-friendly Windows
®
models in which input parameters are
more easily changed, and output is available on the screen, and it can be printed or
saved to a file. The code of the BASIC models can be changed, and they can serve
as a template for building other models. The calculations in the Windows models
cannot be modified by the user. In all cases, the code can be inspected; it is fully
transparent.
The following BASIC models are available.
LEVEL1A
A Level I program treating four compartments. It prompts for chemical properties
and amount. The phase volumes and properties can be changed by editing the
program.