Sewage Treatment Plant

Sewage Treatment Plant

A sewage treatment plant (STP) is a facility designed to remove contaminants from wastewater, primarily from household sewage, before releasing the treated effluent into the environment.

The treatment process typically involves several stages:

• Preliminary Treatment:
  • Screens remove large objects like sticks, rags, and plastic.
  • Grit chambers allow sand and small stones to settle out.
• Primary Treatment:
  • Wastewater flows into large tanks where solids settle to the bottom.
  • Oils and greases rise to the surface and are skimmed off.
  • This process removes about 60-70% of suspended solids.
• Secondary Treatment:
  vBiological processes break down dissolved and suspended organic matter
  • Commonly uses activated sludge process or trickling filters.
  • Bacteria and other microorganisms consume organic matter.
  • Secondary settling tanks remove microbial biomass.
• Tertiary Treatment (Advanced):
  • Further removes nutrients like nitrogen and phosphorus.
  • May include filtration and disinfection (e.g., chlorination, UV light).
• Sludge Treatment:
  • Solids removed during treatment are processed separately.
  • May involve digestion, dewatering, and potential reuse as fertilizer.

The treated water, meeting environmental standards, is then discharged into water bodies or reused for irrigation or industrial purposes.