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WASTE WATER TREATMENT (PRIMARY TREATMENT (Pre-treatment/screening (traps…
WASTE WATER TREATMENT
PRIMARY TREATMENT
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Pre-treatment/screening
traps things like vegetable matter, paper, cloth & plastics
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sedimentation
following the pre-treatment, the water moves on to a clarifier or settling tank
under very calm conditions, sewage solids settle to the bottom of the tank
Not all of the solids are removed in the primary clarifier
-very small, light particles take too long to settle.
The solids collected at the bottom of the tank which are called primary sludge are then pumped from the tank for treatment elsewhere in the plant
TERTIARY TREATMENT
the removal of special contaminants such as organic chemicals, nutrients & pathogens
the final cleaning process that improves wastewater quality before it is reused, recycled or discharged to the environment
removes remaining inorganic compounds, and substances, such as the nitrogen and phosphorus
Bacteria, viruses and parasites, which are harmful to public health, are also removed at this stage
SECONDARY TREATMENT
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Activated Sludge
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The level of oxygen in the wastewater is changed at different stages
- to produce aerobic & anaerobic environment
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different 'communities' of bacteria remove different 'pollution' components from the water during the treatment processes
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Typically aerobes, which can degrade pollutants 10-100 times faster than anaerobes, are utilized most frequently in this treatment process
Clarifier
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Some of the solids collected in the secondary clarifier are sent back to the aeration tank for re-treatment
The excess (waste activated sludge) is pumped to another location in the plant for further treatment.
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