Effluent Treatment Plant

By Author: Pawan
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Effluent Treatment Plant
Effluent Treatment Plant (ETP) is wastewater treatment method which is particularly designed to purify industrial wastewater for its reuse and its aim is to release safe water to the environment from the harmful effect caused by the effluent.
Industrial effluents contain various materials, counting on the industry. Some effluents contain oils and grease, and a few contain toxic materials (e.g., cyanide). Effluents from food and beverage factories contain degradable organic pollutants. Since industrial wastewater contains a diversity of impurities and thus specific treatment technology called ETP is required.
The ETP Plant works at various levels and involves various physical, chemical, biological and membrane processes to treat wastewater from different industrial sectors like chemicals, drugs, pharmaceuticals, refineries, dairy, ready mix plants & textiles, etc.
Benefits of ETP:
1. to wash industry effluent and recycle it for further use
2. To reduce the usage of freshwater in industries
3. To preserve the natural environment against pollution
4. to ...
... satisfy the standards for emission of pollutants set by the govt & avoid heavy penalty
5. To reduce expenditure on water acquisition

2. Industrial Effluent Treatment Process:
The treatment of various effluents varies with the sort of effluent. Wastewater enters the effluent or sewage treatment plant and goes through several processes before effluent goes into the environment. Industrial effluent treatment enation includes the subsequent stages:
a. Preliminary Treatment: Its objective is the physical separation of large-sized contaminants. For example, cloth, paper, plastics, wood logs, etc. This level/process include:
Screening: this is often the primary unit operation that happens in wastewater treatment plants. A screen may be a device with uniform openings and its purpose is to get rid of large floating solids.
Sedimentation: it's a physical water treatment process using gravity to get rid of suspended solids from water.
Grit Chamber: The wastewater that moves into the grit chamber removes the dense inorganic solids like gravel, metal fragments, and sand which have made their way into the sewers. Removal of grit can prevent damaging of pumps & operational difficulties.
Clarifiers: These are tanks built with mechanical means for continuous removal of solids being deposited by sedimentation before biological treatment.

b. Primary Treatment: Its aim is that the removal of floating and settleable materials like suspended solids and organic matter. In this treatment, both physical and chemical methods are used. It includes:
Flocculation: Flocculation may be a physical process and does not involve the neutralization of charge. It involves the addition of destabilized particles together into large aggregates in order that they will be easily separated from the water.
Coagulation: may be a process during which coagulants are added for the aim of rapid settlement of minute solid particles during a liquid into a bigger mass. It permits particle removal by sedimentation and for filtration.
Neutralization: the most purpose of this process helps in maintaining the pH range of 6-9 to satisfy the wants of various processing units within the ETP system.
Primary Clarifiers: These are wont to slow the speed of the water to some extent where organic solids will settle to rock bottom of the tank and it contains equipment that's wont to remove floating solids and greases from the surface.

c. Secondary or Biological Treatment: the target of this treatment is that the further treatment of the effluent from primary treatment to get rid of the suspended solids and residual organics. In this step, biological and chemical processes are involved.
Activated Sludge Process: this is often used for treating industrial wastewater using air and a biological floc composed of bacteria.
Aerated Lagoons: This is a treatment pond provided with artificial aeration to promote the biological oxidation of wastewater.
Trickling Filters: Trickling filters, also referred to as sprinkling filters, are commonly used for the biological treatment of domestic sewage and industrial wastewater.
Rotating Biological Contactor: It involves allowing the wastewater to return in touch with a biological medium to get rid of pollutants within the wastewater before the discharge of the treated wastewater to the environment.
d. Tertiary/advanced/disinfection treatment: the aim of tertiary treatment is to supply a final treatment stage to boost the effluent quality to the specified level before it's reused, recycled, or discharged to the environment.
Chemical Coagulation and sedimentation: it's wont to increase the removal of solids from effluent after primary and secondary treatment.
Filtration: The clarified wastewater is first skilled the adjacent filtration plant which contains large filter blocks to make sure high-quality water.
Reverse Osmosis: In this process, the pressure is used to force effluent through a membrane that retains contaminants on one side and allows the clean water to pass to the other side.
UV Disinfection: It is considered as an ideal disinfectant for industrial wastewater. It leaves no residual disinfectant in the water by ensuring the water quality. It does not produce any disinfection by-products.