What are the main stages in an effluent treatment plant process?

Introduction

Effluent Treatment Plant (ETP) is an important system that is used by industries and factories to manage wastewater before it is released into the environment. These plants make sure that all the harmful pollutants are removed from the wastewater. The effluent treatment plant process ensures that the treated water is safe and compliant with environmental standards.

To make the optimal use of these plants, it is important to understand its main stages. 

Effluent Treatment Plant Process

Let’s understand the steps followed by the ETP for wastewater treatment:

1. Preliminary Treatment

This is the first stage of wastewater treatment, whose main objective is to remove the large solid particles and debris from the water that could damage the equipment. 

This stage typically includes:

• Screening: In this stage, screens are used to remove large objects such as sticks, leaves, plastic, etc. from the water. This leads to smoother functioning of the process and plant.
• Grit Removal: This stage is usually carried out to remove sand, gravel, or any other heavy particles from the water using the descenders and degreasers. 

2. Primary Treatment

This is the second stage whose main objective is to remove the part of suspended solids and organic matter. It mainly focuses on removing settleable and floatable materials. 

This stage consists of:

• Sedimentation: In this phase, wastewater is allowed to settle in large tanks called primary clarifiers. With the help of this process, settleable solids form sludge at the bottom, whereas grease and oils float on the surface and are removed. 
• Sludge Removal: The formed sludge at the bottom of the tank is removed and sent for further treatment or disposal. 

During this process, some chemicals such as coagulants and flocculants can also be added to improve the sedimentation of solids and remove phosphorus. Moreover, in some cases, bases and acidic agents are also used to neutralize the water’s pH.

3. Secondary Treatment

The main objective of secondary treatment is to remove dissolved organic matter and nutrients such as nitrogen and phosphorus from the water. 

This treatment mainly focuses on biological processes such as using bacteria and microorganisms to break down organic pollutants. 

This stage includes the following process:

• Aeration: This stage involves mixing wastewater with air to provide oxygen that promotes the growth of aerobic bacteria that decompose the organic matter. For this process, aeration tanks or bioreactors are used. 
• Biological Treatment: Using a variety of processes such as the activated sludge process, trickling filters, and bio-towers, bacteria eat organic matter to produce biomass, carbon dioxide, and water. 
• Secondary Clarification: The treated water is then passed through secondary clarifiers where the activated sludge settles down in the tank, and the clear water is collected on top for further treatment.

4. Tertiary Treatment

The main objective of tertiary treatment is to remove the residual contaminants and pollutants. 

This is the last stage of cleaning wastewater which includes:

• Filtration: In this process, sand filters and membrane filters are used to remove the remaining suspended solids and microorganisms.
• Disinfection: Different methods like chlorination, ultraviolet radiation, or ozonation are used to kill the remaining pathogens.
• Nutrient Removal: Processes like biological nutrient removal are used to remove excess nitrogen and phosphorus, which can cause eutrophication in receiving waters.

5. Sludge Treatment and Disposal

The main objective of sludge treatment is to safely dispose of produced sludge during primary and secondary treatments.

The sludge treatment includes:

• Thickening: In this process, sludge is thickened by reducing the water volume to be treated. 
• Digestion: The mixed sludge is digested by aerobic or anaerobic processes to stabilize the growth of bacteria and to remove them.
• Dewatering: In this process, water is removed from the digested sludge, making it easier to handle using techniques like centrifugation. 
• Disposal: This dewatered sludge is disposed of in landfills, or used as fertilizer if it meets safety standards. 

Conclusion

Effluent treatment plants play an important role in protecting our water bodies by treating wastewater released by industry. Each stage that is followed by the plant is designed to remove different types of contaminants, making sure that the wastewater is purified before releasing into the environment or for reuse.  

In addition, industries should understand this process to make the optimal use of the plant and contribute to making a sustainable environment.

At Mentor Water Experts, we provide different solutions for wastewater treatment, such as installation services, operator training and many more. 

If you are looking for any AMC services for your effluent treatment plant or looking to install an effluent treatment plant, contact us at 735 100 2123 and get a free consultation on your first visit.