ANAEROBIC TREATMENT OF TANNERY WASTE
David G. Bailey, Research Leader
Michael H. Tunick, Research Chemist
Eastern Regional Research Center
U.S. Department of Agriculture
Philadelphia, Pennsylvania 19118
Alexander A. Friedman, Professor
Department of Civil Engineering
Syracuse University
Syracuse, New York 13210
George B. Rest, Project Engineer
O'Brien and Gere Engineers, Inc.
Syracuse, New York 13211
INTRODUCTION
Tannery wastewaters are notoriously difficult to treat due to the presence of high concentrations
of slowly biodegradable proteins, high levels of sulfide and extreme pH values. The combination of
the high strength organics and other objectionable constituents often create problems for on-site treatment and for discharge of untreated effluents to publicly owned treatment works (POTWs). Energy
and space intensive aerobic processes are necessary for existing on-site treatment prior to direct discharge. Issuance of the 1979 proposed effluent limitations by the Environmental Protection Agency
[1], which contained stringent tannery discharge standards, have served as the impetus for seeking
more effective and economical methods for treating tannery wastes. This paper describes the results of
two companion studies that were designed to evaluate: (1) anaerobic roughing treatment of tannery
wastewaters; and (2) the amenability of resulting anaerobic effluents to subsequent aerobic polishing.
The first of these bench-scale studies used beamhouse wastewater pretreated to remove sulfide as substrate for anaerobic filters (AF), followed by aerobic rotating biological contactor (RBC) polishing of
the filter effluent. The second study used tannery wastewater without pretreatment as substrate for an
anaerobic contact reactor followed by activated sludge treatment for the polishing step. While the
results of these studies may be applied directly to the treatment of tannery wastewaters, the operational findings may have significance for the anaerobic treatment of other industrial waste streams
with similar constituents.
NATURE OF LEATHER MANUFACTURE
The domestic industry is currently projected to tan approximately 15 million of the 38 million
hides produced in this country in 1983. There are approximately 180 tanners which U. S. EPA has separated into nine distinct categories. Category 1 is the largest group and consists of tanners that chemically dissolve the hair, tan with chromium and produce finished leather as a final product. Fifteen of
the 180 tanners are direct dischargers and must meet the 1985 regulations as promulgated in November of 1982 [2]. The remainder are indirect dischargers and must meet at least the pretreatment mini-
mums described in the same document. State and local regulations are already more stringent in some
cases.
Tanning is the general term for the process by which hides and skins are converted into leather.
The first six steps of this process are carried out in batch operations where aqueous solutions of a vari-
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