Do you want to learn more about the mechanics behind a wastewater treatment plant? Read more about anaerobic digestion here!

1. Understanding Wastewater
Treatment

2. Wastewater treatment is the process through
which contaminants are removed from household,
municipal, or industrial sewage and water is made
safe for release into the environment. In natural
settings water purification is accomplished
through dilution and decomposition; wastewater
treatment is an industrialized and standardized
variation of natural processes that uses a
combination of physical, chemical, and biological
procedures. There are five components to
wastewater treatment, though the extent of the
processing in any given system will vary by
location and government. The process of
wastewater treatment includes: pretreatment,
primary, secondary, and tertiary treatment, and
polishing.

3. Pretreatment allows large debris like trash or tree
limbs to be removed from wastewater prior to
entering the more sensitive mechanized stages of
processing.

4. The first stage of treatment is the physical removal
of biological solid wastes from wastewater.
Biological solids include such items as hair, food,
or feces. This first stage of treatment collects
wastewater for a regulated period of time during
which solid materials will settle to the bottom; fats
and oils rise to the top. Physical implements then
physically separate the wastewater from both
solids and oils.

5. Secondary treatment is typically a biological
process and closely approximates what occurs in
nature. Various native bacteria and microbes are
cultivated to decompose the organic compounds in
wastewater. This stage can be accomplished
through the use of aerated basins, constructed
wetlands, or soil biotechnology.

6. Tertiary treatment is most frequently used in areas
where there is a concern of excess nutrients from
treated wastewater entering the environment. This
level of processing removes excess phosphorous
and nitrogen from water through chemical or
biological means. An excess of nutrients could
result in eutrophication, i.e. algal bloom, and
cause impaired environmental conditions for many
oxygen-sensitive species.

7. Polishing is a fifth level of wastewater treatment.
It is chemical disinfection, often via chlorination.