Bio-Oxidation of
Concentrated Board Machine Effluents
T. P. QUIRK, Assistant Professor of Civil Engineering
Manhattan College
Bronx, New York
R. C.  OLSON, Manager
Process Engineering
Wood Conversion Company
Cloquet, Minnesota
G. H. RICHARDSON, Chemist
E. H. Ruble & Associates
Duluth, Minnesota
INTRODUCTION
The biological oxidation of pulp and paper mill effluents has been the subject
of considerable basic and applied research. Both fixed bed trickling filters, and
fluid bed activated sludge systems have been employed in numerous designs (1, 2,
3,4, 5). In general, full scale operating experience has been limited to relatively
dilute effluents with five-day BOD concentrations ranging from 150 to 750 ppm.
The process feasibility of bio-oxidation for these effluents has been well established.
Available cost information varies widely depending upon the degree of BOD
removal, the treatment process employed, and the number of unit operations included in the system design. For a specified BOD reduction and treatment system
annual costs per pound removed may be expected to vary inversely with the BOD
concentration of the feed wastes. Published data indicate removal cost for secondary treatment ranging from less than $2 per hundred lbs removed to more than $7
per hundred lbs for primary effluent concentrations varying from 200 to 500 ppm
(5,6,7).
Water conservation procedures are therefore essential in reducing organic
losses as well as the volume of liquid handled. Experience has demonstrated,
however, that a limit may be reached where the total quantity of dissolved solids
discharged remains essentially constant. Additional machine close-up increases
the concentration of oxygen consuming materials in proportion to the decrease in
effluent volume. The treatment characteristics and cost requirements of these
concentrated effluents require individual evaluation.
This paper describes the results of a laboratory scale study conducted to determine the feasibility of bio-oxidation of concentrated machine wastes from the
production of mineral and wood fiber insulating boards. The study is part of an
overall program of pollution control designed to evaluate the relative costs of in-
mill conservation measures and external treatment systems.
WASTE CHARACTERISTICS
The Cloquet, Minnesota, mill of the Wood Conversion Company, manufactures decorative and insulating boards from mineral and wood fiber raw material.
Effluent waters are discharged into the St. Louis River. Wastes originate primarily from pulping and machine room operations and vary widely depending upon
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