Effluent from various manufacturing industries, such as pharma, chemical, food, textile, and tanneries, is contaminated and toxic and must be treated before discharge into the environment. Effluent Treatment Plants (ETP) or Common Effluent Treatment Plant (CETP) are the treatment systems or plants used to treat industrial effluent. Wastewater Treatment Plant is another name for Effluent Treatment Plant (WWTP).
When space is limited in industrial clusters, Common Effluent Treatment Plants (CETP) are used. CETPs reduce operational costs, save space, and have a higher diluting potential, resulting in more amenable degradation and organised disposal of Treated Water.
The design of ETP is dependent on Physical, Chemical and Biological parameters of Wastewater. These parameters include:
Physical Parameters such as the presence of suspended solids, temperature, and color.
Chemical Parameters such as Total Dissolved Solids, Organic/ Inorganic matter present, Alkalinity, Hardness, Nutrients present, Heavy metals, Fluorides, Chlorides, Dissolved Oxygen & Nitrogen and pesticides or other toxic chemicals.
Biological Parameters include the presence of microbial pathogens in wastewater such as Bacteria, viruses, Protozoa. Microscopic flora and fauna present possesses a potential threat to life.
Design of ETP or Common Effluent Treatment Plant is dependent upon Physical, Chemical, and Biological Parameters of the Effluent and required parameter of the treated water. As a result, ETP can be divided into the following levels.
- Preliminary Level
- Primary Level
- Secondary Level
- Tertiary or Advanced Level
1. Preliminary Treatment
Physical separation of large-sized impurities such as poly bags, cloths, wood logs, and so on is performed at this level. Screening (generally with a maximum size of 10 mm), Sedimentation, and Clarification are the physical units used in this process..
2. Primary Treatment
Floating and settleable material such as suspended solids and organic matter screened at this stage using both physical and chemical processes. Coagulation, precipitation, flocculation, and dissolved air flotation enlists some of the chemical processes used.
3. Secondary Treatment
Secondary Treatment level involved removal of a biologically degradable material and suspended matter from wastewater using biological and chemical processes. Therefore, the bacteria-based biological processes allows removal or reduction of organic and inorganic matter concentration.
3. Tertiary or Advanced Treatment
Additionally this stage involves the removal of nitrogen, phosphorus, and other pathogens. This stage includes Reverse Osmosis, Ultra Filtration, Micro-filtration, and other units.