Lecture series 12 - Civil and Environmental Engineering | SIU

CE 510
Hazardous Waste Engineering
Department of Civil Engineering
Southern Illinois University Carbondale
Instructor: Dr. L.R. Chevalier
Lecture Series 12
Design of Selected Pathway Applications
Course Goals
 Review the history and impact of environmental
laws in the United States
Understand the terminology, nomenclature, and
significance of properties of hazardous wastes
and hazardous materials
Develop strategies to find information of
nomenclature, transport and behavior, and
toxicity for hazardous compounds
Predict the behavior of hazardous chemicals in
surface impoundments, soils, groundwater and
treatment systems
Assess the toxicity and risk associated with
exposure to hazardous chemicals
Application of scientific principles of hazardous
wastes to their design, management,
remediation and treatment
Sorption by GAC
 Has along history of use as a treatment
for municipal, industrial, and
hazardous waste streams
 Is a relatively non-specific adsorbent
and is effective for removing many
organic and some inorganic
contaminants from liquid and gaseous
Sorption Design Application
GAC Contactors
 Design Procedures:- outcomes of
design effort are:
Mass and volume of carbon necessary to
treat a given volume of water before
regeneration is required
System configuration (number of columns
in series
Proposed dimension of the system
Sorption design Application
C/Co vs. service time
Time in operation
Sorption design Application
 GAC Design Methods
Mass loading or Isotherm Data method
 Uses loading values (isotherm data) for specific
 Does not account for non-equilibrium
Operating line method
 Accounts for mass transfer and diffusion into
pores within the carbon
Finite Element Method
 Accounts for mass transfer, dispersion and
competitive sorption by different contaminants
Schematic of a GAC system
Source: USEPA
Pilot column Studies
 Effective procedure for designing full-scale
GAC contactors
 Relative contaminant concentration is
measured as a function of time
 Water to be treated is pumped through a
series of columns that are 5-10 cm in
diameter and 2-3 m deep.
 Contaminant concentration is measured as a
function of time, and the data are converted
to relative contaminant concentration.
System configuration of pilot
scale GAC evaluation
Analysis of Pilot System Data
 Most common method is the graphical
analysis of the breakthrough curve.
 Bed Depth-Service Time (BDST) analysis is
used in drinking water and industrial
hazardous waste treatment
 Horizontal lines are drawn through each
curves at C/Co=0.10 and C/Co=0.90 which
represent break-through and exhaustion
points respectively.
Analysis of Pilot System Data
Analysis of Pilot System Data
 The horizontal distance between the exhaustion line
and breakthrough line is defined as the height of the
adsorption zone (D).
t = ax + b
Analysis of Pilot System Data
 From the fit of the data, the constants a and b may be analyzed
further to develop parameters that can be used for full-scale
 The slope, a is defined as

N = sorptive capacity of the carbon
Co = influent contaminant concentration (mg/L)
 = superficial velocity through column [m3/(m2-h)]
Analysis of Pilot System Data
 The intercept, b is defined as
 =  ℎ = (
)x ln[
− 1]

Where, K = the adsorption rate constant [m3/(kg-h)]
C = contaminant concentration at breakthrough (mg/L)
The minimum column depth to obtain an acceptable effluent
concentration, the critical bed depth, is found from the intercept of the
C/Co=0.1 line where t=0.

ℎ  ℎ =

  ( )


.   . ( 3)

System Scale-Up
The total number of columns in series (based on the height of the

adsorption zone), n, is:  = + 1

Where, D = height of the adsorption zone (m)
d = height of the pilot columns (m)
The loading rate on the pilot columns is calculated as:  =

This loading rate may be used to calculate the area of the full
scale columns as:  =

Where; V = column loading rate [m3/(m2-day)]
Qp = pilot column flow rate (m3/day)
Ap = cross sectional area of the pilot columns (m2)
Qf = full-scale flow rate (m3/day)
Af = area of full-scale contactor (m2)
Class Example

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