Process Flowchart of Effluent Treatment Plant (ETP)

Last updated on February 21st, 2024 at 07:19 pm

Effluent can be defined as the excess chemical liquor which is discharged after using original operation.

Effluent is defined by the United States Environmental Protection Agency as “wastewater – treated or untreated – that flows out of a treatment plant, sewer, or industrial outfall. Generally refers to wastes discharged into surface waters”. The Compact Oxford English Dictionary defines effluent as “liquid waste or sewage discharged into a river or the sea”.

Effluent Treatment Plant is a plant that is used to treat the effluent and make it environment friendly. The process flow chart of ETP is shown in the following fig:

Steps of the Effluent Treatment Plant

Steps	Description
Screening	Screening is the first unit operation in ETP plant. The screen is a perforated device that is used to retain the coarser materials found in wastewater. When the solid materials come in contact with the screen they stack and are removed manually or mechanically. This process is called Screening.
Flow Equalization	Flow equalization is a system which is used to reduce the operational problems created by flow variations, to accelerate the downstream process. In case of any process failure in the treatment process, it is also used as an emergency tank to equalize the effluent. It ensures the constant or nearly constant flow rate of the effluent.
Coagulation	It takes place in rapid mix basins which is very rapid. The key function of the rapid mix basin is to disperse the coagulant so that it contacts all of the effluents.
Flocculation	It is done to form aggregates from the finely divided matter. The flocculation of effluent is done in two ways. One is mechanical and another is agitation. In both mechanical and air agitation systems, it is common practice to taper the energy input so that the aggregates initially formed will not be broken as they leave the flocculation facilities.
Neutralization	Generally, industrial wastewater contains acidic or alkaline components which should be neutralized before discharge or treatment. Especially sulphuric acid, lime, etc. are used to neutralize the wastewater.
Primary Clarifier	The primary clarification is a physical treatment process. In this process, solids are removed before the biological process. After the basic screening, it is the most cost-effective way to remove these solids. When the process water enters the clarifier tank, floatable solids are removed from the surface by skimmers while settleable solids are collected at the bottom by a rack and are removed via a sludge removal system.
Biological Treatment	There are many biological processes that are used for wastewater treatment. The processes can be divided into five major groups: aerobic process, anoxic process, anaerobic process, combined aerobic anoxic and anaerobic process.

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Steps of the Effluent Treatment Plant

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