FACTORS TO CONSIDER WHEN TREATING DYE WASTES
WITH GRANULAR ACTIVATED CARBON
Paschal B. DeJohn, Project Leader
ICI United States, Inc.
Specialty Chemicals Division
Wilmington, Delaware 19897
INTRODUCTION
It has been demonstrated that activated carbon is an effective method for removing
color and other pollutants from textile and dye wastes [1-4].   This paper will discuss the
treatment of these wastes by granular activated carbons manufactured from lignite and
bituminous coal.
Information will be provided to aid in the evaluation and selection of granular carbon
for textile and/or dye wastes.   Data will be presented showing
the effect of wastewater storage on carbon performance.
the major design parameters needed to size a granular carbon system.
the effect of temperature on carbon adsorption.
• the relationship of dye molecular weight on carbon adsorption (% color removal
and carbon loading).
• comparative adsorption performances of lignite and bituminous coal carbons on
dye wastes.
• the effect of thermal regeneration on carbon performance.
• system design cautions.
GRANULAR CARBON EVALUATION USING STORED SAMPLES
The granular carbon evaluation process usually involves isotherm work followed by
column studies.    Isotherms are run to
• determine if carbon can reduce the impurity level to the desired quantity.
• determine the relative size of the pollutant molecules in a given waste (comparative isotherms).
• obtain an approximation of the maximum quantity of impurity that can be
adsorbed by a unit weight of carbon.
• get an idea of how difficult it is to adsorb a given pollutant (estimated from
the slope of the isotherm).
• get an idea of the relative adsorbability of the pollutants in a mixed component
waste (the slope of the isotherm will not be a straight line-instead it will be a
series of broken lines).
• determine if it is worthwhile conducting time-consuming column studies.
Column studies are run to develop data for designing a granular carbon system.    The
major design parameter for the adsorption portion of the system is the contact or residence time between the carbon and the wastewater.    The optimum residence time determines the size of the adsorbers and volume of the carbon bed.    Residence time
information cannot be obtained from an isotherm.
There are two major design parameters needed to size the regeneration portion of a
granular carbon system.    They are the carbon usage or exhaustion rate and the residence
time of the carbon in the furnace.    The carbon usage rate tells one how much carbon
must be reactivated per day.   This can be determined from the column study.    The
furnace residence time will depend on the type and amount of organics that the carbon adsorbs.    This design parameter is obtained either from running regeneration tests
or from the furnace manufacturer directly.
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