BORON IN INCINERATOR QUENCH WATER
Nathan C. Burbank, Jr., Professor
School of Public Health
University of Hawaii
Honolulu, Hawaii 96822
INTRODUCTION
In the design and operation of solid waste disposal facilities the incinerator has long
held a unique position in that the reduction of volume was maximum and heat recovery
could be practiced with the accepted engineering techniques. Often it could be located
in an industrial-zoned area within excellent hauling distance from the sources of generation and a reasonable distance from the ash disposal site. Further, and most important,
the wastewater generated by the process could be easily discharged to the municipal sewer
and, when diluted with domestic sewage, the waste posed no problems for usual sewage
treatment processes.
In Honolulu the 600-ton/day city and county incinerator was located at a point considered the most convenient from the standpoint of projected population centers in Wai-
pahu, a sleepy sugar mill settlement located on the shore of the West Loch of Pearl
Harbor, the very area where the oysters grow.   The untreated incinerator waste was directed into the sewage collection system which went to a newly constructed oxidation pond.
From the day of startup the oxidation ponds suffered.   The incinerator waste was
clearly defined as a significant contributor to the problem and an effective method of
treatment of the waste was determined [ 1 ].   As an immediate correction measure, the
waste stream was removed from the sewer system and discharged indirectly to a ditch
leading to Pearl Harbor.   Surprisingly enough, there were no repercussions either from the
oysters, the fish or the conservationist watchdogs of the area.
With the prospect of an increase in size of the incinerator, enforcement of more stringent air pollution control measures and an increase in waste flow investigations were undertaken to determine if the wastewater could be further recycled in-plant and any waste
resulting treated for land disposal.   A municipal golf course nearby was currently being
irrigated with potable water so reuse and operational savings were excellent prospects.
SOURCES OF INCINERATOR WASTE (LIQUID)
Wastewater emanates from an incinerator at several points:   the fly ash handling system,
the gas scrubbers and the residue quench system.   Further, on cleanup, there may be additional wash water used for flushing the wet scrubbers, either venturi or wet baffle or
shower type.
The liquid wastes from incinerators have been investigated and in general the pH varies
from 3.9 to 11.2 with the majority of wastes in the highly alkaline range.   Total solids is
high-usually in the order of 3000-5000 mg/1; suspended solids are in the range of 150-500
mg/1.   The 5-day BOD is usually very low, while the COD may vary from 450 to 3000
mg/1.   Dependent on the operation of the unit, the alkalinity may vary from a low of
5 mg/1 to as much as 1000 mg/1.   Chlorides may vary from as low as 100 to as much as
1000 mg/1.   Hardness (as CaC03) may range from 100 to as much as 2000 mg/1.   Usually the waste contains quantities of trace elements such as zinc, nickel, copper, arsenic,
selenium, chromium, silica and boron.   These combined with sodium and potassium are
often significant if the wastewater is to be utilized in connection with any biological
activity.   Table I shows the analysis of the Waipahu Incinerator Process Wastewater as
discharged.
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