Sludge Management Strategy - ProMinent DULCOMETER PH-501 Assembly And Operating Instructions Manual

Operation & Maintenance Manual
Sewage Treatment Plant
December 2018
modules are continually air scoured to induce flow of mixed liquor over the flat sheet membrane surface
and prevent fouling and buildup of solids on the membrane surface without the use of chemicals. The
mixed liquor is then transferred to the inlet of the biological treatment to maintain even distribution of
solids throughout the system and to introduce activated biology to the raw sewage. Newterra
MicroClear membranes are produced with true ultrafiltration membrane material with 0.04 μm pore size,
which blocks all bacteria and most viruses. Secondary disinfection is not required to exceed effluent
requirements. Figure 9 presents a schematic view of the UF process.
Figure 9 – Membrane filtration concept
2.1.3

Sludge Management Strategy

As solid-laden sewage enters the system and solid-free effluent is discharged, the suspended solids
concentration in the mixed liquor suspended solids (MLSS) will increase. To maintain the proper level
of MLSS, solids must be removed from the system as Waste Activated Sludge (WAS) which is mixed
liquor discharged from the aerobic tank at approximately 0.8% dry. WAS is discharged to a tank for
holding and decanting. The holding tank is aerated to maintain an aerobic environment to reduce odors.
In the decanting process the WAS is allowed to settle and supernatant is pumped off, and returned to
the MBR, thickening the sludge in the holding tank. By thickening the sludge to approximately 2% dry
solids by weight, the total volume that must be disposed of is decreased, extending holding time and
reducing operational costs. Level control in the tank indicates when the tank should be decanted or a
vacuum truck should be scheduled to dispose of the WAS.
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