TM 5-814-8
Table 5-4 Cent'd
8.
Process Flexibility -
Lack of flexibility refers to the
unavailability of
valves,
piping and other appurtenances
required to operate in various modes or to include or exclude
existing processes as necessary to optimize performance. Poor
flexibility precludes the ability to operate an activated
sludge plant in the contact stabilization, step loading or con-
ventional modes and the ability to bypass polishing ponds or
other downstream processes to discharge high quality secondary
clarifier effluent. Either the lack of or inadequate process
flexibility was noted as the leading cause of poor performance
at three plants and was a factor at 37 facilities.
90
Ineffective O&M Manual Instruction - This situation, existing
at 40 plants, was judged serious although the adverse effect
was moderate.
The poor quality of most plants' O&M manuals
undoubtedly has contributed to operators' general lack of
understanding of the importance of process control and the
inability to practice it, but a competent staff could use other
available information sources.
10. Aerator Design - Deficiencies in aerator design were the major
cause of poor performance at six facilities and were less
significant factors at an additional 21 plants.
Deficiencies
were noted in the type, size, shape, capacity, and location of
the unit and were of such a nature as to hinder adequate treat-
ment of the waste flow and loading and stable operation.
ers, dissolved or induced air flotation system,
(4) Upgrading to provide increased organic
filtration units, and oil/water separators.
loading capactiy. Biological units are most af-
(a) Reducing volumes. Hydraulic overload-
fected by organic overloading. Specifically, waste
ing may be caused by peak flows in excess of
stabilization ponds, activated sludge systems,
plant design or by average flows exceeding plant
trickling filters, and rotary biological contractors
design capacity. Peak flows may be remedied by
are among the more easily affected systems. In
installing equalization basins which will dampen
these systems, organic overloading often results
the peaks to acceptable average flow levels.
in poor sludge settleability, sludge bulking and
Average loading in excess of hydraulic capacity
odor problems. Increased secondary sludge pro-
may be remedied in many cases by elimination of
duction caused by overloading could result in
infiltration and inflow. Decreased industrial water
problems with sludge thickeners, digesters,
use or water recycle may also help to eliminate
dewatering and disposal facilities. When over-
hydraulic overloading.
loaded, many biological systems not only exhibit
(b) Process modifications. Process modifica-
decreased removal efficiencies, but in severe or-
tions may be used to increase the hydraulic
ganic overloading situations they may fail com-
capacity of an existing system. The addition of
pletely. Aerobic systems may become anaerobic
chemical coagulant greatly enhances the effi-
and/or the organisms may become completely
ciency of most hydraulic based units. Equipment
unsettleable due to filamentous bulking. In acti-
has been developed to increase hydraulic capacity
vated sludge systems, organic overloading may
in some units, such as, tube settlers in clarifiers
sometimes result from inadequate mixing which
and corrugated plate interceptors in oil/water
leads to sludge settling in the aeration basin thus
separators. If none of these methods provide
reducing the effective biomass in the system.
sufficient increases, construction of parallel units
may be necessary.
This problem can be solved by increasing the
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