Treatment and Sludge
Disposal of Wastes from the
Manufacture of Activated Carbon
S. A. LaROCCA, Supervisor of Sanitary Engineering
Central Engineering Department
Atlas Chemical Industries, Inc.
Wilmington, Delaware
W. W. ECKENFELDER, JR., Professor
J. F. MALINA, JR., Associate Professor
University of Texas
Austin, Texas
INTRODUCTION
A variety of raw materials and processes are used to make activated carbons.
Waste characteristics from plant to plant will vary accordingly.
This paper is concerned with the wastes generated from the activated carbon
manufacturing facilities of Atlas Chemical Industries, Inc. , at Marshall, Texas,
and more specifically to the removal of inorganic suspended solids, with emphasis
on the concentration and dewatering of the resultant sludge.
WASTE WATER GENERATED
Strip-mined lignite is the raw material used in the Atlas Darco plant. The
lignite is crushed to particles less than one in. in size and activated in rotary kilns
at temperatures in excess of 800 C. Acid and waterwashing precede final drying,
grinding and grading.   The process is shown diagrammatically in Figure 1.
The process steps remove various impurities from the lignite and promote ad-
sorptive pores in the carbon particles. The impurities can be generally classified
as: volatile matter, non-volatile silaceous ash and non-volatile inorganic elements and compounds.
The high temperature activation removes the volatiles as gases and generates
fly ash, which is subsequently trapped in draft seals and dust collectors by wet
sluicing systems. The inorganic impurities, mainly calcium, iron, magnesium
and aluminum, are extracted by washing. Inorganic acids are the principal wash
media.
The resultant taw waste stream, as indicated in Figure 1, is comprised mainly
of the following: fly ash suspended solids, activated carbon suspended solids from
production losses and dissolved salts of calcium, magnesium, iron and aluminum.
The wastes pH range is about 2. 0 to 4. 0.
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