It is the initial step which involves following steps: Preliminary Treatment. Screening. Grit Chamber. Sedimentation.
To separate and remove large matter which might negatively affect the efficiency of later treatment procedures
Grit chambers are to remove the inorganic particles like stones, sand etc
Is a physical water treatment process using gravity to remove suspended solids from water.
It is the second process in which 90% of organic matter remove by microbial activity. Types: Lagoons Trickling Filter Activated Sludge
An lagoon or aerated basin is a holding and/or treatment pond provided with artificial aeration to promote the biological oxidation of wastewaters.
A trickling filter has inert materials like rocks, gravel, slag, etc. over which the wastewater flows Bio-film is formed Wastewater sprayed over the inert material having microbes which decompose the waste matter in water
In activated sludge sewage is treated using air and microbes composed of bacteria and protozoa.
It involves chemical process for pollutants which are left after primary and secondary treatment. Extremely costly.
◦ Processes: Bleaching to remove coloration Disinfection to kill pathogens Coagulation-sedimentation with alum Adsorption using activated charcoal Electro-dialysis for salt removal Nitrogen Control Biological Phosphorus Control Carbon Adsorption