Industrial waste water ( Effluent ) treatment describes the process used for treating waste water produced by industries as an undesirable by-product. After treatment, the treated waste water may be reused or released to a Sanitary sewer or to a surface water in the environment.
FEATURES:
- To remove all inorganic & organic through physical, chemical and biological process
- To clean industry effluent and recycle it for further use.
- To reduced the usage of fresh/potable water in industries.
- To cut expenditure on water procurement.
- To meet the standards for emission or discharge of environmental pollutants from various industries set by the government and avoid hefty penalties.
- To safeguard environment against pollution and contribute in sustainable development
Design of ETP:-
The design and size of the ETP depends upon:
- Quality and quality of the industries discharge effluent.
- Land availability.
- Monetary consideration for construction, operation & maintenance.
Treatment Levels & Mechanisms of ETP:–
Treatment Levels:
- Preliminary
- Primary
- Secondary
- Tertiary ( or advanced )
Treatment Mechanisms:
- Physical
- Chemical
- Biological
Preliminary Treatment Level:
Purpose: Physical separation of big sized impurities like cloth, plastics, wood logs, paper, etc.Common physical unit operations at Preliminary level are:
Screening : A screen with openings of uniform size is used to remove large solids such as plastics, cloths etc. Generally maximum 10mm is used.
Sedimentation: Physical water treatment process using gravity to remove suspended solids from water.
Clarification: Used for separation of solids from fluids.
Tertiary / Advanced Treatment:
Purpose :- Final cleaning process that improves wastewater quality before it is reused, recycled or discharged to the environment.
Mechanism:- Removes remaining inorganic compounds, and substances, such as the nitrogen and phosphorus. Bacteria, viruses and parasites, which are harmful to public health, are also removed at this stage.
Methods:-
- Alum : Used to help remove additional phosphorus particles and group the remaining solids together for easy removal in the filters.
- Chlorine contact tank disinfects the tertiary treated waste water by removing microorganisms in treated waste water including bacteria, viruses and parasites.
- Remaining chlorine is removed by adding sodium bisulphate just before it’s discharged.
Primary Treatment Level:
Purpose: Removal of floating and settleable materials such as suspended solids and organic matter.
Method: Both physical and chemical methods are used in this treatment level.
Chemical unit process:
- Chemical unit processes are always used with physical operations and may also be used with biological treatment process.
- Chemical processes use the addition of chemicals to the waste water to bring about changes in its quality.
- Example: pH control, coagulation, chemical precipitation and oxidation.
pH Control:
- To adjust the pH in the treatment process to make wastewater pH neutral.
- For acidic wastes ( low pH ): NaOH, Na2Co3, CaCO3 or Ca(OH)2.
- For alkali wastes ( high pH): H2SO4, HCL.
Chemical coagulation and Flocculation:
- Coagulation refer to collecting the minute solid particles dispersed in a liquid into a larger mass.
- Chemical coagulants like AL(SO4)3 { also called alum } or Fe2(SO4)3 are added to wastewater to improve the attraction among fine particles so that they come together and form larger particles called flocks.
- A chemical flocculent ( usually a polyelectrolyte ) enhances the flocculation process by bringing together particles to form larger flocks, which settle out more quickly.
- Flocculation is aided by gentle mixing which causes the particles to collide.
Secondary Treatment Level:
Methods: Biological and chemical processes are involved in this level.
Biological unit process:
- To remove, or reduce the concentration of organic and inorganic compounds.
- Biological treatment process can take many forms but all are based around microorganisms, mainly bacteria.
Aerobic Processes:
- Aerobic treatment processes take place in the presence of air ( OXYGEN ).
- Utilizes those microorganisms ( aerobes ), which use molecular/free oxygen to assimilate organic impurities i.e. convert them into carbon dioxide, water and biomass.
Anaerobic Processes:
- The anaerobic treatment processes take place in the absence
- Utilizes microorganisms (anaerobes) which do not require air (molecular/ free oxygen ) to assimilate organic impurities.
- The final products are methane and biomass.

Ongoing Effluent Treatment Plant Projects
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