Aerated Stabilization of Board Mill
White Water
HERMAN R. AMBERG, Manager
Chemical and Biological Research
Central Research Division
Crown Zellerbach Corporation
Camas, Washington
INTRODUCTION
Stabilization basins are widely used by the pulp and paper industry as a form
of secondary treatment. Early experimental work conducted by the National
Council for Stream Improvement (1) showed that white water from paper or board
mills was amenable to stabilization and any degree of BOD reduction within reason
could be attained depending upon the retention. The importance of surface adsorption of oxygen was clearly shown in these studies. In general, most of the
BOD reduction was accomplished in the upper layers of the stabilization pond and
it is accepted today that depth should not exceed three to five ft. The importance
of periodic or continuous aeration was also demonstrated in the early studies (1,2).
For example, low rate aeration for a period of four days resulted in a BOD reduction in excess of 90 per cent while an unaerated waste was reduced only 40 per
cent after 14 days of storage.
These stabilization basins are not strictly dependent upon aerobic microorganisms but depend upon both aerobic and anaerobic microorganisms for efficient
purification. For these reasons loading is extremely critical if nuisance problems
are to be avoided. It has been found by field studies that nuisance problems associated with hydrogen sulfide generation and other putrefactive odors can be kept
under control by limiting the BOD load to about 25 to 50 lbs/acre/day. This
readily points to the need for tremendous space requirements which normally
are not available at existing mill sites. Since natural reaeration is not adequate
to supply the required oxygen for high rate treatment, higher loadings can only be
attained by supplemental aeration.
Over the past ten years, waste treatment measures have been initiated at the
Baltimore Division of Crown Zellerbach Corporation at Baltimore, Ohio, designed
specifically to improve water quality of the receiving stream, Little Walnut
Creek. This mill produces about 150 to 200 tons per day of board and corrugating
medium using waste paper as furnish. The major source of BOD containing waste
is the white water from the two paper machines.
In 1950, the first unit of the present treatment plant, a Marx Saveall was installed to remove settleable solids. Additional treatment facilities were installed
In 1955 and 1956 consisting of two primary settling lagoons and a stabilization
lagoon. Recirculation pumps were also installed to recirculate the oxidation lagoon contents. Ratliff (3) reported on the efficiency of the oxidation lagoons and
calculations indicated that the recirculating oxidation lagoon was removing about
2000 lbs/BOD/day at a BOD load of about 1100 lbs/acre/day. In 1957, a trickling filter and a final settling lagoon were installed and a portion of the treatment
plant effluent was pumped to a 15-acre irrigation field. This treatment plant was
capable of removing about 70 to 75 per cent of the applied BOD load.
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