Secondary Treatment of Wastes from
An Alum Tannery
EDWARD L. THACKSTON, Associate Professor
Environmental and Water Resources Engineering
Vanderbilt University
Nashville, Tennessee 37203
INTRODUCTION
In 1967, the Caldwell Lace Leather Company, of Auburn, Kentucky, was awarded
research and demonstration grant No. WPRD 25-01, by the Federal Water Pollution
Control Administration, now part of the Environmental Protection Agency (EPA), to
develop and demonstrate methods for the treatment of tannery wastes.
This tannery is unusual, and possibly unique, in that all three major tanning processes
— chrome tanning, alum tanning, and vegetable tanning — are carried out at the same
location. Thus, there was an opportunity to work with a wide variety of waste streams, and
to determine the effect each would have on the waste treatment process. In addition to the
actual tanning processes, the waste treatment plant would also be required to handle the
wastes from the leather finishing operations, such as fat liquoring and dyeing.
The tannery is located on the bank of Black Lick Creek, a small stream which rises
about 0.5 miles south of the town of Auburn. The stream then flows northward through the
town and adjacent farmland for about three miles until it disappears in a series of sinkholes
and enters the underground water streams which flow through the cavernous limestone
which underlies most of central Kentucky.
In the first phase of this project, the Caldwell Lace Leather Company awarded a
contract to Vanderbilt University, of Nashville, Tennessee, to investigate the characteristics
of the different waste streams and to develop treatment methods. This "research phase" of
the project was completed in September, 1967, and the results were reported by Tomlinson,
Thackston, et al (1, 2).
The consulting firm of Howard K. Bell and Associates, of Lexington, Kentucky, was
retained to design a treatment plant embodying the concepts and features recommended by
the research team. The treatment plant design was approved by the Kentucky Department
of Health and bids for construction were called for. Because of difficulties in construction
unrelated to the treatment process or the plant design, completion of construction was
delayed until December, 1970.
Difficulties in start-up were also encountered, and it was May, 1971, before the
treatment plant began functioning smoothly. In November, 1971, a team from the EPA
conducted a survey of operation of the treatment plant to determine the effectiveness of the
treatment being provided.
WASTE LOADS
The leather production facilities of Caldwell Lace Leather Company generally could
be described as typical of a small tannery. The manufacturing processes are conducted by
use of conventional lime pits, fleshing and unhairing machines, rotary drums, and rocker
vats (for vegetable tanning). Approximately 85 percent of the leather production at this
plant at the time of the study was by the alum tanning process, with chrome-tanned leather
and vegetable-tanned leather accounting for approximately equal fractions of the
remaining 15 percent. Figure 1 is a schematic representation of the alum tanning process.
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