Effluent Treatment Plant

Industries through waste liquor into rivers, canals etc. Before flowing this liquid to outward, the plant which treats this effluent to a harmless form for the environment is known as Effluent Treatment Plant (ETP). ETP not only covers the mechanisms but also the processes, to used treat water that have been polluted in some way by man-made industrial or commercial activities prior to its release either into the environment or re-use.

The ETP designed to treat effluent coming from different areas of the plant. The treatment of different effluents varies with the characteristics of effluent. Wastewater treatment consists of a combination of physical, chemical, and biological processes and operations to remove solids, organic matter and, sometimes, nutrients from wastewater. General terms used to describe different degrees of treatment, in order of increasing treatment level, are preliminary, primary, secondary, and tertiary and/or advanced wastewater treatment. In some countries, disinfection to remove pathogens sometimes follows the last treatment step.

Preliminary treatment

The objective of preliminary treatment is the removal of coarse solids and other large materials that are found in effluent. Removal of these materials is necessary to enhance the operation and maintenance of subsequent treatment units. Preliminary treatment operations typically include coarse screening, grit removal and, in some cases, breaking of large objects into the smaller objects.

Primary treatment

Primary treatment usually includes the removal of large solids from the wastewater via physical settling or filtration.

The objective of primary treatment is the removal of settleable organic and inorganic solids by sedimentation, and the removal of materials that will float (scum) by skimming. Approximately 25 to 50% of the incoming biochemical oxygen demand (BOD5), 50 to 70% of the total suspended solids (SS), and 65% of the oil and grease are removed during primary treatment. Some organic nitrogen, organic phosphorus, and heavy metals associated with solids are also removed during primary sedimentation but colloidal and dissolved constituents are not affected. The effluent from primary sedimentation units is referred to as primary effluent.

Secondary treatment

The objective of secondary treatment is the further treatment of the effluent from primary treatment to remove the residual organics and suspended solids. Secondary treatment typically removes the smaller solids and particles remaining in the wastewater through fine filtration aided by the use of membranes or through the use of microbes, which utilize organics as an energy source. In most cases, secondary treatment follows primary treatment and involves the removal of biodegradable dissolved and colloidal organic matter using aerobic biological treatment processes. Aerobic biological treatment is performed in the presence of oxygen by aerobic microorganisms (principally bacteria) that metabolize the organic matter in the wastewater, thereby producing more microorganisms and inorganic end-products (principally CO2, NH3, and H2O). Several aerobic biological processes are used for secondary treatment differing primarily in the manner in which oxygen is supplied to the microorganisms and in the rate at which organisms metabolize the organic matter.

Tertiary and/or advanced treatment

Tertiary treatment is the next wastewater treatment process after secondary treatment. This step removes stubborn contaminants that secondary treatment was not able to clean up. Wastewater effluent becomes even cleaner in this treatment process through the use of stronger and more advanced treatment systems

Individual treatment processes are necessary to remove nitrogen, phosphorus, additional suspended solids, refractory organics, heavy metals and dissolved solids. Because advanced treatment usually follows high-rate secondary treatment, it is sometimes referred to as tertiary treatment. However, advanced treatment processes are sometimes combined with primary or secondary treatment (e.g., chemical addition to primary clarifiers or aeration basins to remove phosphorus) or used in place of secondary treatment (e.g., overland flow treatment of primary effluent).


Disinfection normally involves the injection of a chlorine solution at the head end of a chlorine contact basin. The chlorine dosage depends upon the strength of the wastewater and other factors. Ozone and ultra violet (uv) irradiation can also be used for disinfection but these methods of disinfection are not in common use.

Electro plating industry
Iron and Steel (involving processing from ore/ integrated steel plants and or Sponge Iron Unit
Fermentation Industry (Distilleries, Maltries and Breweries)
Milk processing and dairy products (integrated project)
Food Industries
Automobiles industries (Integrated facilities)/ Automobiles servicing, repairing and painting (excluding only fuel dispencing)
Pulp and Paper industry
Thermal power plants
Slaughter House, Meat & Sea Food Industry
Food and Fruit Processing Industry
Tanning industry
Metal industry
Textile Industries/ Man-made fiber (synthetic)/ Woolen Mills/Cotton/Yarn/ textile processing involving any effluent/ emission- generating process ,bleaching, dyeing, printing and scouring
Rice Mills with boiler/furnance and dry rice mills
Cement Plants
Fertilizer Industry
Pesticide Manufacturing and Formulation Industry
Paint Industry
Hotel Industry (Hotels (10 rooms and above) /Restaurants having 30 chairs & above)
Inorganic Chemical Industry
Glass Industry
Ceramic Industry
Edible Oil & Vanaspati Industry
Pharmaceutical industry
Soda Ash Industry (Solvay process)
Lead acid battery manufacturing (excluding assembling & charging of acid lead batteries.
Ferrous and Non ferrous metal extraction involving different furnaces through melting, refining, reprocessing, casting and alloy making
Synthetic fibers including rayon, tyre cord, polyster filament yarn
Health care establishment (20 Beds & Above)
Manufacturing of Paints, Varnishes, pigments and intermediate (excluding blending/ mixing) etc.