Design an ETP for Edible Oil Refinery Industry
Effluent treatment plants (ETPs) are an essential part of the edible oil/ vegetable oil/ cooking oil/ refinery industry. In this blog, we will discuss the design of an effluent treatment plant for this industry. We will provide a process flow diagram and explain the working functions of each stage in detail.
Design Basis:
The design of the effluent treatment plant is based on the following parameters:
- Inlet flow rate: 100 m3/h
- Inlet COD: 4000 ppm
- Inlet BOD: 1500 ppm
- Inlet TSS: 500 ppm
- Inlet oil and grease: 200 ppm
- Inlet pH: 6.5 - 8.5
- Inlet temperature: 40°C
- Discharge limit: COD - 250 ppm, BOD - 50 ppm, TSS - 30 ppm, oil and grease - 10 ppm, pH - 6.5 - 8.5
Process Flow Diagram:
The effluent treatment plant for the edible oil/ vegetable oil/ cooking oil/ refinery industry consists of the following stages:
Working Functions:
- Screening and Grit Removal: The screening and grit removal stage involves the removal of large solids and grit from the wastewater. The wastewater is passed through a bar screen and a grit chamber. The bar screen removes large solids while the grit chamber removes grit and sand from the wastewater.
- Equalization Tank: The equalization tank is designed to receive and store the wastewater from the screening and grit removal stage. It helps in maintaining a consistent flow rate and pH. The equalization tank will have a volume of 30 m3 and a retention time of 2 hours.
- Chemical Treatment: The chemical treatment stage involves the addition of chemicals such as alum and polymer to the wastewater. These chemicals help in the removal of suspended solids and organic matter. The wastewater is then mixed in the flocculation tank.
- Flocculation Tank: The flocculation tank is designed to mix the wastewater with the chemicals added in the chemical treatment stage. The tank is equipped with a mixer to ensure proper mixing of the wastewater and chemicals.
- Sedimentation Tank: The sedimentation tank is designed to allow the solids to settle to the bottom of the tank. The clear water on top is then transferred to the dissolved air flotation unit. The sedimentation tank will have a retention time of 2 hours.
- Dissolved Air Flotation: The dissolved air flotation unit is designed to remove the remaining suspended solids, oil and grease from the wastewater. The wastewater is mixed with air and chemicals in the flotation tank. The air bubbles attach to the suspended solids and oil droplets, causing them to float to the surface.
- Biological Treatment: The biological treatment stage involves the use of activated sludge to remove the organic matter from the wastewater. The wastewater is mixed with activated sludge in an aeration tank. The aeration tank is equipped with a blower to supply oxygen to the microorganisms.
- Secondary Sedimentation Tank: The secondary sedimentation tank is designed to allow the activated sludge to settle to the bottom of the tank. The clear water on top is then transferred to the tertiary treatment stage. The secondary sedimentation tank will have a retention time of 2 hours.
- Tertiary Treatment: The tertiary treatment stage involves the use of filtration and disinfection to remove any remaining impurities and pathogens from the wastewater. The wastewater is passed through sand filters to remove any remaining suspended solids. It is then disinfected using chlorine to kill any remaining pathogens.
- Disinfection: The final stage of the effluent treatment plant is disinfection. The effluent is disinfected using chlorine to ensure that it meets the discharge limits. The chlorine is added to the effluent in a contact tank, and the effluent is then held for a minimum contact time of 30 minutes.
- Effluent Storage and Discharge: The final stage of the effluent treatment plant is the storage and discharge of the treated effluent. The treated effluent is stored in an effluent storage tank before it is discharged into the receiving water body. The discharge of the effluent must comply with the discharge limits.
Conclusion:
The design of an effluent treatment plant for the edible oil/ vegetable oil/ cooking oil/ refinery industry requires careful consideration of the inlet flow rate and quality, discharge limits, and the specific treatment processes required. The process flow diagram and working functions provided in this blog provide a comprehensive overview of the design of such a plant.
It is important to note that the design of an effluent treatment plant may vary depending on the specific requirements of the industry and the regulations in the area. Therefore, it is important to consult with a qualified professional and obtain the necessary permits before designing and constructing an effluent treatment plant.
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