Secondary treatment is designed to substantially degrade the biodegradable organic matter and suspended solids.
The majority of municipal plants treat the settled sewage liquor using aerobic biological processes.
This pollution mainly derived from human waste, food waste, soaps, detergent etc.
To be effective, the biota requires both oxygen and food to live. The bacteria and protozoa consume biodegradable soluble organic contaminants. (e.g. sugars, fats, organic short-chain carbon molecules, etc.) and bind much of the less soluble fractions into flocs. The final step in the secondary treatment stage is to settle out the biological floc or filter material through a secondary clarifier and to produce sewage water containing low levels of organic material and suspended matter.
- Diffuser different style for aeration.
- Mixer for mixing and avoiding of sedimentation
- Scraper different style to collect and remove settled sludge
- Scum and oil removal [Skimmer] for removal of floating material