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Raw wastewater (called influent) from the sewer system
enters the treatment plant at the headworks. Here, the
wastewater passes through two mechanical bar screens
that remove large debris, rags, sticks or other objects
that may damage equipment used in the treatment process.
The Influent then flows through two Parshall flumes which
measure the flow rate and the total amount of wastewater
treated by the plant. Wastewater is then pumped to the
Grit Chambers which removes sand, gravel and metallic
objects. The removal of solids improve treatment efficiency
and help protect the equipment against excessive wear. |
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The odor control facility reduces odors emitted by
wastewater. The primary treatment areas (headworks, grit
chambers and primary clarifiers) are covered to trap
these odors. The trapped odors are then vacuumed and
treated by a chemical process which reduces the pollutants.
Treated air is then released into the atmosphere. |
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The clarifiers remove floatable and settleable materials
from the wastewater. The water is detained in the clarifier
for 2.5 hours. This allows the majority of solids (sludge)
to separate from the liquid portion and collect at the
bottom of the tank. The solids or sludge is then mechanically
collected and pumped to the digesters. Meanwhile, the
floatable waste (or scum) is skimmed off the top of the
water and is also pumped to the digesters. The remaining
liquid portion flows by gravity to the trickling filter. |
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Wastewater is distributed over the honeycomb-like
plastic filter media which is covered with a thin bacterial
growth. Microorganisms grow on the media and absorb much
of the organic content found in the wastewater. When
the growth becomes too large, it breaks off and is passed
to the next phase of treatment. |
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This is the final treatment step. The
secondary clarifiers provide a quiescent condition
which promotes settling of the bacterial growth from
the trickling filters and also any solids or scum not
removed during primary sedimentation. The collected
sludge and scum is pumped back to the headworks to
repeat the treatment process. |
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The lagoon equalizes the daily peaks
in flow to the downstream disposal systems by providing
temporary storage. It also provides a habitat for water
loving fowl. |
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At the final effluent pump station,
treated wastewater flows to either the Interstate-5
pipeline or one of the four storage reservoirs. The
Interstate-5 pipeline transports the effluent to a
4,700 acre restricted farm operation located southwest
of Bakersfield. It is operated by the City of Los Angeles. |
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Sludge collected from the primary clarifiers
is pumped to the digesters for treatment. Sludge from
the secondary clarifiers is routed back to the headworks
and will repeat the treatment process. No sludge is
collected in the trickling filters. |
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Collected sludge is pumped into heated tanks called
Digesters. Anaerobic (absence of oxygen) bacteria thrive
in the digesters, and convert raw sewage sludge to an
inert material (digested sludge), methane gas and carbon
dioxide. This process takes about two to three weeks. |
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Digested sludge, from the digesters, is distributed
to the sludge drying beds. The liquid portion of the
sludge is evaporated or decanted and returned back
to the headworks to repeat the treatment process. When
the
sludge has dried it is tested for pollutants. When
approved, the sludge will be spread on the City’s
farm land where only restricted crops are grown (non-human
consumption).
The dried sludge is categorized as Grade B quality;
it is safe and relatively odor free |
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Digester gas (approximately 60% methane, 40% carbon
dioxide) is produced by anaerobic bacteria in the digesters.
The gas is collected and fuels an engine generator which
produces 200 kilowatts of continuous electrical power
for use in the treatment plant. Waste heat recovered
from the engine is used to heat the digesters. |
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The operations building provides a central location
for plant personnel. It contains the main control room
which is used to operate and monitor the treatment process.
In addition, it houses offices, a laboratory, and the
lunch/training room.
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The City’s Treatment Plant 3 laboratory maintains
a Department of Health Services, Environmental laboratory
Accreditation Program (ELAP) Certificate No. 1884 in
fields of testing # 16 and # 17 for conventional pollutant
and heavy metal analysis. Influent, Pri-Effluent, and
Final Effluent are analyzed frequently to confirm the
treatment plant is operating as designed. |
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The Standby Generator has a capacity of 800 kilowatts
and burns diesel fuel. The standby power can run all
essential processes in the event of a power failure. |
