The primary principle of a Sewage Treatment Plant (STP) is to
treat wastewater from domestic and industrial sources to remove contaminants and produce an
effluent safe for release into the environment or for reuse.
Process:
Preliminary Treatment :
Removes large debris, grit, and floating materials.
Primary Treatment :
Settling of solids (primary clarifiers) to reduce suspended solids and organic
material.
Secondary Treatment :
Biological treatment using microorganisms (e.g., activated sludge) to further
degrade
organic matter.
Tertiary Treatment :
Advanced filtration, disinfection (chlorination, UV), and other methods to further
purify
the water.
B. Effluent Treatment Plant (ETP)
Effluent Treatment Plants are designed to treat industrial effluents
to reduce the environmental impact of discharged wastewater, meeting regulatory standards.
Process:
Pre-Treatment :
Removal of large solids, oils, and grease.
Primary Treatment :
Physical and chemical separation (sedimentation or flotation).
Secondary Treatment :
Biological processes (such as activated sludge) or chemical treatments to reduce
organic load.
Tertiary Treatment :
Advanced filtration, reverse osmosis, or ion-exchange methods.
C. Zero Liquid Discharge Plant (ZLD)
Zero Liquid Discharge (ZLD) plants aim to minimize wastewater
discharge by treating and recovering all water from the wastewater. The goal is to achieve a "zero"
discharge of liquid waste, and all effluents are treated, recovered, and reused.
Process:
Pre-Treatment :
Removal of large solids and chemicals.
Evaporation :
Wastewater is evaporated to separate water from solid residues.
Reverse Osmosis (RO) :
Concentrated waste is further treated with RO to recover clean water.
Crystallization :
Final solid waste is turned into crystallized salts, ensuring minimal liquid
discharge.
D. Desalination Plant
Desalination is the process of removing salts and minerals from
seawater to produce fresh, potable water.
Process:
Pre-Treatment :
Removal of debris, organic material, and suspended solids.
Reverse Osmosis (RO) :
Seawater is forced through semi-permeable membranes to remove salts.
Post-Treatment :
Minerals like calcium and magnesium are added to make the water suitable for
consumption.
E. Water Reclamation Plant
Water reclamation involves the treatment and reuse of wastewater for non-potable or potable purposes, significantly reducing fresh water consumption.
Process:
Primary Treatment :
Removal of large particles and debris.
Secondary Treatment :
Biological treatment to degrade organic material.
Tertiary Treatment :
Advanced filtration, reverse osmosis, and disinfection to ensure the water meets the required standards for its intended use (e.g., irrigation, industrial processes, or potable water).
Crystallization :
Final solid waste is turned into crystallized salts, ensuring minimal liquid
discharge.
