Removal of
COD from Wastewater by Fly Ash
PRODIP K. DEB, Project Engineer
ALAN J. RUBIN, Assistant Professor
Civil Engineering Department
University of Cincinnati
Cincinnati, Ohio
ARTHUR W. LAUNDER, Sanitary Engineer
Monsanto Company
St. Louis, Missouri
K. H. MANCY, Assistant Professor
School of Public Health
University of Michigan
Ann Arbor, Michigan
INTRODUCTION
Considerable emphasis has been placed on research concerned with the removal of biologically resistant material from polluted waters. The evaluation of
processes capable of performing such treatment is based on the efficiency of removal and economic feasibility. Among the several currently known physical,
chemical and biological methods used for the removal of organic refractory materials from wastewater, adsorption has been indicated as the most promising
technique (1).
The literature on adsorption reveals that activated carbon is more frequently
used as an adsorbent than any other material. The high organophilic character of
activated carbon makes it an efficient scavenger of organic refractories in wastewater renovation operations and so it has found its largest market in industrial and
municipal water purification (2).
However, activated carbon has several disadvantages; the powdered forms
cost from seven to nine cents per pound, and the granular types cost from 25 to
50 cents per lb (3). In addition, an economical regeneration process for the
costly adsorbent is yet to be developed.
These economic drawbacks of active carbon have initiated an interest in low
cost, but less efficient, adsorbents. Many investigators have studied the feasibility
of using such substances, including a variety of clays, minerals, and industrial
by-products (4,5).
With the advent of modern coal firing methods, large quantities of a solid
combustion by-product has come into being. Commonly designated fly ash, this
by-product has created a disposal problem for many utilities, including the electric power industry. While fly ash is a disposal problem to such utilities, the need
for an economical adsorbent, available in large quantities, is a need faced by
many wastewater renovation programs.
Literature survey has revealed that fly ash has been used in a variety of applications,  including the construction of roads, dams and bridges, the making of
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