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Biological System Water Treatment
Process Description
Biologic system pretreatment wastewater comes
from several sources. Small communities, strip malls, industrial
parks, septic tank haulers, and industrial companies that do not have
sanitary sewer available, and therefore have to treat their own
wastewater. The wastewater is generated when domestic wastewater
and light industrial wastewater are combined and have to be treated
together. For example a strip mall on a rural highway that has a
motel and a coffee shop or maybe a bakery, or an industrial park
with light industrial. The DAF is used to remove some solids,
floating material and oils and reduce suspended solids prior to the
biologic system to reduce the load. This enables the biologic
system to be smaller, produce less sludge and avoid
performance issues due to the presence of oils and greases.
Biologic System Pretreatment wastewater is
treated by simply processing direct to the DAF or by adding a
flocculent. The goal of the DAF here is
to to produce a consistent waste stream and reduce the load on the biologic system.
The typical method to treat Biologic System
Pretreatment wastewater is as follows:
Stage 1 - Flash Mix:
The wastewater is introduced to the flash mix zone where a polymer
flocculent is added. This stage maximizes flocculent dispersion
throughout the wastewater.
Stage 2 - Flocculation:
The wastewater is now introduced to the slow mix zone to agglomerate
the floc into larger particles suitable to be enmeshed with the air
bubbles.
Clarifier, Dissolved Air Flotation (DAF):
The flocculated wastewater is introduced into the DAF inlet where
the floc particles are comingled with a pressurized dissolved fine
bubble recycle stream. The floc particles attach to the bubbles and
float to the surface where they are mechanically skimmed into the
float scum sludge chamber. The clarified treated water then exits
the end of the DAF and flows downstream to sewer or further
treatment if necessary. The DAF system bubbles come from a Recycle
Air Dissolving system that takes a portion of treated effluent,
pressurizes it and introduces air to be dissolved. The dissolved
air comes out of solution and forms a fine bubble stream when the
pressure is released at the DAF entrance in the presence of floc
wastewater.
DAF
Sludge Handling:
The resulting DAF waste scum/sludge is removed from the DAF
automatically as the scum accumulates and is pumped to the biologic
solids tank and handling equipment.
Sludge Dewatering:
The sludge should be processed with the biologic system sludge and
disposed of in accordance with environmental regulations.
APPLICATIONS:
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