TM 5-814-8
--Segregation.
be generated by the marketing of reclaimable
--Recirculation and recycling.
substances such as oils or solvents.
--Disposal of concentrated residuals.
(4) Pretreatment. Isolated waste streams may
--Pretreatment.
be treated locally for removal of specific constitu-
--Reduction in volume or waste load.
ents before discharge to the main collection
--Process modification.
system. Such pretreatment is possible in a vehicle
(1) Segregation. Segregation means isolating
maintenance area by installation of an oil/water
the waste streams originating from various
separator on the sewer which collects floor wash-
sources or types of sources from others. Segrega-
ings. A number of treatment processes may be
tion usually involves controlling the manner in
used for pretreatment as illustrated in table 5-1.
which wastes are collected. Often, segregation of
(5) Reduction in volume or waste load by
waste streams is the key to implementing in-
better housekeeping. A close examination of most
plant control because each source may require
processes will reveal a number of operations
individual consideration. Segregation may be nec-
which result in unnecessary dumping to the
essary before any of the other in-plant controls
sewer. Needless flushing of spilled materials,
can be exercised. For example, in order to reclaim
emptying of old or used containers, running of
waste oils, it is necessary to collect used oil
unused hoses, and leaking of worn equipment are
before it enters the sewer. Thus, segregation is
all examples where reduction can be effective. In
the key to oil reclamation. Potential undesirable
many cases, good housekeeping practices, proper
effects of segregation should also be considered.
management, adequate supervision and everyday
These arise whenever two streams which are
common sense can be applied to reduce waste
complimentary in some respect are segregated.
discharges.
When an acidic stream is segregated from a basic
(6) Process modification. In considering the
in-plant controls, a frequently overlooked method
stream pH adjustment problems may intensify.
is modification of the operation which generates
Similarly, warm and cold streams are sometimes
the waste. Modification can occur by either chang-
better treated when combined due to temperature
effects on treatment efficiency. A nutrient con-
ing or replacing the equipment or materials
taining waste stream is desirable in a mixture of
employed in the operation. Equipment modifica-
predominantly carbonaceous waste and should,
tion could involve repair, renovation or replace-
therefore, not be segregated. All these and similar
ment of existing process machinery. An example
factors should be considered whenever segrega-
of this would be to replace a wet scrubber with a
tion is contemplated.
cyclone or fabric filter to remove cinders from a
(2) Water recirculation and recycling. In-
waste paper incinerator. The replacement of chem-
plant control by recirculation and recycling refers
icals and materials used with ones having less
to the reuse of wastewaters from some operation
pollutional impact can also have a significant
either within that operation or within another
in-plant control.
operation. Recirculation and recycling may re-
(7) Combined sewers. Many sewer systems
quire some form of local treatment in order to
have served as combined sewers handling both
render the wastewater recyclable. An example of
sanitary and storm flows. In some instances, this
a case where treatment is not necessary would be
was purposely planned to eliminate the need for
heat recovery from laundry wastewater to preheat
two separate systems. However, this practice was
boiler water. An example of a waste that requires
implemented prior to the time when any signifi-
treatment before reuse would be the filtering of
cant waste treatment was required. Today, com-
water in a wet spray booth scrubber before
bined sewers do not exist to a significant extent
recycling. These operations will result primarily in
on military installations and are prohibited in new
construction. If a combined sewer is encountered
reduced hydraulic loading of the treatment plant.
during modification of an existing facility, the
(3) Disposal of concentrated residuals. In
stormwater flow should be separated from the
some instances, wastes can be collected in a
process flow.
semi-dry or otherwise concentrated state and
(8) Cooling water. Water used for indirect
recovered for reuse or separate disposal. Potential
cooling purposes (such as shell and tube heat
benefits of special disposal are enhancement of
exchangers) normally contains essentially no BOD
e n d - o f - p i p e treatment due to a reduction in
or suspended solids. Once-through cooling waters
pollutional load or by elimination of toxic or
can be diverted from the sanitary sewer system.
otherwise hazardous material which may be detri-
For recirculating evaporative cooling systems,
mental to end-of-pipe treatment. Income can also
5-6
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