Environmental Engineering Reference
In-Depth Information
5
ChaPTer
WasTeWaTer ColleCTion
and PreliMinary
TreaTMenT
In the late 1970s and early 1980s, under the Code of Federal
Regulations (CFR), 40 CFR Part 403 was established to help Publicly
Owned Treatment Works (POTW) control industrial discharges to sew-
ers. These regulations were designed to prevent pass-through and inter-
ference at the treatment plants and interference in the collection and
transmission systems.
Pass-through
occurs when pollutants literally
“pass through” a POTW without being properly treated, resulting in
an effluent violation for the POTW or an increase in the magnitude or
duration of a violation.
Interference
occurs when a pollutant discharge
causes a POTW to violate its permit by inhibiting or disrupting treat-
ment processes, treatment operations, or processes related to sludge
use or disposal.
5.1 inTroduCTion
Figure 5.1 shows a basic schematic of an example wastewater treat-
ment process providing primary and secondary treatment using the
activated sludge process
. This is the model, the prototype, the para-
digm used in this handbook. Although secondary treatment (which pro-
vides BOD removal beyond what is achievable by simple sedimentation)
commonly utilizes three different approaches—trickling filter, activated
sludge, and oxidation ponds—our focus throughout this handbook, for
instructive and illustrative purposes, is on only the activated sludge
process. Figure 5.1 allows the reader to follow the treatment process
step by step as it is presented (and as it is actually configured in the
real world) and to assist in demonstrating how all of the various unit
