Wastewater treatment refers to the process of removing pollutants from water previously employed for industrial, agricultural, or municipal uses. The techniques used to remove the pollutants present in wastewater can be broken into biological, chemical, physical and energetic. These different techniques are applied through the many stages of wastewater treatment.
Primary treatment usually includes the removal of
large solids from the wastewater via physical settling or filtration.
The first step in primary treatment is screening.
Secondary treatment typically removes the
smaller solids and particles remaining in the wastewater through fine
filtration aided by the use of membranes or through the use of microbes,
which utilize organics as an energy source. Energetic techniques may
also be employed in tandem with biological techniques in the secondary
phase to break up the size of particles thus increasing their surface
area and rate of consumption by the microbes present. A common first
step in the secondary treatment process is to send the waste to an aeration tank.
Tertiary treatment involves the disinfection of
the wastewater through chemical or energetic means. Increasing the
number of steps in a wastewater treatment process may insure higher
quality of effluent; however employing additional technologies may incur
increased costs of construction, operation, and maintenance.
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