Oxidation Pond Study for
Treatment of De-inking Wastes
RUSSELL O. BLOSSER, Resident Engineer
National Council for Stream Improvement
Kalamazoo College
Kalamazoo, Michigan
There has been a substantial amount of research and development work
in the paper industry employing low rate biological oxidation processes. The
application of the low rate processes was demonstrated in the laboratory about
ten yrs ago by Moggio and Amberg in a search to find methods that would accelerate the BOD removal obtained in long time storage of effluents (1), (2).
Essentially their work showed that the rate of biological decomposition was
influenced by the amount of dissolved oxygen furnished the system, the rate
increasing as the liquid approached a true aerobic state. The rate was influenced by the nitrogen and phosphorous level present. The rate was also
improved by the increase of micro flora and fauna present as a result of
seeding.
The application of one or more of these three fundamental factors has led
to the development of low rate biological systems that accomplish BOD removal at a greater rate than is possible by storage or lagooning of effluents
under quiescent conditions. Since quiescent storage of effluent from the paper
industry must depend on surface absorption as a source of oxygen, a source
normally not adequate to maintain a dissolved oxygen residual in the system,
supplemental aeration by some mechanical means must be practiced to accelerate biological oxidation.
When dissolved oxygen is maintained in the system and aeration periods
exceed about one day these systems have been called aerobic stabilization
systems to differentiate them from an activated sludge process.
There is no established procedure for operation of aerobic stabilization
systems. In almost all cases a good job of primary sedimentation is mandatory
prior to the aeration period if large deposits of sludge are to be avoided in the
aeration basin. The degree of mixing provided for high suspended solids effluents must be high if excessive sludge deposits in the aeration basin are to
be avoided. There is usually sufficient biological coagulation and an accumulation of biological sludge which will settle in the aeration basin if not
kept in suspension, or which may be removed in a secondary clarifier.
The laboratory work in the development of the aerobic stabilization
process for de-inking waste was conducted by the National Council and the
process was pilot planted at Hamilton Paper Company in a project sponsored
by the Kalamazoo River Improvement Company.
LABORATORY INVESTIGATION
An acclimated seed was prepared by four-day aeration of a mixture containing 20 per cent effluent from the activated sludge process and 80 per cent
settled de-inking waste. At the end of the aeration period the mixture was
settled and the supernatant added to clarified de-inking waste at a seed to
feed rate of one to four.
- 87 -