Amenability of a Mixture of
Sewage, Cereal, and Board Mill
Wastes to Biological Treatment
Thomas P. Quirk, Sanitary Engineer
Malcolm Pirnie Engineers
New York, N. Y.
The design of waste disposal plants receiving domestic and industrial
discharges invariably requires special consideration of the treatment
process selected, the type of process equipment required, and the particular operational problems associated with the combined wastes. When
the design of these treatment systems envisions the use of aerobic biological treatment, the functional requirements of certain industrial effluents become even more vital to the proper operation of the system. The
nature of aerobic biological systems is such that the stability and continued operation of the process is dependent upon maintaining a state
of dynamic equilibrium among a host of variables, many of which are
not subject to the direct control of the system operator. This tenuous
balance requires investigation in the light of the characteristics of the
industrial discharges expected. It is not uncommon for combined industrial and domestic effluents to require waste treatment systems of such
a size and nature that their cost becomes prohibitive.
By the same token, however, the presence of certain industrial wastes
may give properties to the composite discharge which allow the required
treatment units to be significantly reduced in size when compared to
the standards applicable to normal domestic sewage. In addition, the
combined waste may exhibit characteristics which materially enhance
the operation of the entire system.
It is generally advisable, then, to conduct specific pilot-type investigations when the lack of operational experience with the particular waste
leaves many of these questions unanswered. Full pilot-plant scale investigations, while providing the most reliable form of operational data, can
be costly as well as time consuming. In many instances laboratory-scale
studies can provide valuable information concerning process feasibility,
system operation and stability. The knowledge gained from these studies
may justify limiting pilot-plant investigations, if they are required, to
specific areas.
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