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| Pretreatment Manual |
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For more
information, contact David Eppstein by email at
deppstein@masco.harvard.edu,
or by calling 617-632-2860.
3.0 STEP-BY-STEP APPROACH TO DISCHARGE COMPLIANCE
A
facility that experiences a problem complying with sewer
discharge limits should develop a plan of action. As mentioned
in the previous section, some facilities can achieve compliance
with all discharge requirements by implementation of a source
reduction program within the facility. For other facilities, a
source reduction program must be combined with a wastewater
pretreatment system to achieve compliance.
While
no one plan of action to achieve compliance will be appropriate
for all facilities or situations, the following generic
step-by-step approach may be considered. The approach is
depicted in Figure 1, Ten Steps Toward Industrial Wastewater
Discharge Compliance. The first eight steps of the generic
approach can be considered source reduction activities.
As
shown in Figure 1, the first step is to study the possible
pollutant sources within the facility. Each process activity
should be examined for chemical or reagent usage and discharge.
Verifying and quantifying pollutant sources (Step 2) can
sometimes be completed by contacting the chemical or reagent
manufacturers and reviewing their product data.
Tracking
pathways of pollutants within the facility (Step 3) can involve
the facility architectural design drawings and can be assisted
by the development of flow diagrams for each industrial process
and the building waste piping systems. Targeted monitoring to
find pollutant pathways in the facility (Step 4) can require the
installation and use of sampling ports in waste piping systems
at points upstream of the final regulated discharge location.
Information generated by the targeted monitoring can be fed back
to Step 3 to help track pollutant pathways and further back to
Step 1 to supplement the inventory of known pollutant sources.
With
the information generated, candidate source reduction options
can be developed and investigated (Step 5). The source reduction
options that are found to offer good pollutant reductions and
cost savings should be implemented. Since certain source
reduction actions may require changes to current operating
procedures, employee training might be needed for effective and
continuing implementation of these actions (Step 6). Experiences
gained from the training program can feed the further
development of source reduction options (Step 5).
In
addition to such source reduction activities, it may be
appropriate to conduct a wastewater characterization study (Step
7) to more fully define the nature of the wastewater being
discharged. The results of the study can be used to feed the
further development of source reduction options (Step 5) and to
define pretreatment requirements and possible interfering
pollutants (Step 9). Wastewater characterization is discussed in
Section 6.0 of this Manual.
The
information derived from pollutant tracking and the wastewater
characterization study can be used to identify specific
wastestreams that are already meeting discharge standards. Other
specific wastestreams might be identified that could cause
problems for a specific pretreatment technology. The least cost
solution to these situations could be to segregate the complying
and problem wastestreams from the main wastewater stream (Step
8). These types of wastestream segregations can favorably affect
the size, performance, and cost of the pretreatment system. If
implemented, the wastestream segregations may also affect the
available source reduction options (Step 5) and the character of
the main wastewater stream (Step 7). Coordinating source
reduction, source segregation, and pretreatment is discussed in
Section 7.0 of this Manual.
Pretreatment
technologies can be evaluated and implemented if required (Step
9). The steps of a pretreatment technology evaluation process
are discussed in later sections of this Manual. Once the
pretreatment system is selected, designed, and installed, the
effluent from the pretreatment system should be monitored to
meet discharge permit requirements and evaluate system
performance (Step 10). The results of these evaluations can be
used to optimize operations of the pretreatment system and can
be fed back to help in the development of additional
pretreatment process steps (Step 9) and source reduction options
(Step 5). The evaluations can also help in the regular review
and inventory of pollutant sources in the facility (Step 1).
This
step-by-step approach to achieving discharge compliance can be
an iterative process. Feedbacks during the source reduction,
wastewater characterization, and pretreatment steps can
dramatically affect the results. In particular situations, some
of the above steps may be skipped or combined, and the order of
some steps can be reversed. An experienced consulting
engineering firm can provide invaluable services in the
execution of this process. For more information, refer to the
following sections of this Manual.
FIGURE
1
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