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The Two Main Steps of the Wastewater Treatment Process

Wastewater treatment is an extremely important part of making sure that humans treat the earth with respect. The proper treatment of wastewater is essential not only for the environment; due to the use of several chemicals throughout the process, a safe process also keeps employees and your facility safe. Wastewater treatment is usually broken down into two sections: primary treatment, which removes grease, dirt, gravel, and floatable waste, and secondary treatment, which removes even more suspended solids and pollutants by using biological processes.

Primary Treatment

During primary treatment, 40-50% of solids are removed from wastewater. This process usually involves large screens that let water pass through, but not floatable trash and other pollutants. These materials are collected and then properly disposed of. The next part of primary treatment involves the filtration of water through a grit chamber, which allows for the removal of coarse solids like bits of rock, metal, bone, and other larger pieces from the water. This is done for two primary reasons: to keep the water clean, and to prevent the grit from causing damage to the equipment used in wastewater treatment. The last step of primary treatment involves sedimentation, which causes the physical settling of matter. Sedimentation often uses chemicals like flocculants and coagulants.

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Secondary Treatment

The second of the main steps of wastewater treatment is usually the final step to wastewater treatment. It generally removes 85-90% of all the pollutants. During secondary treatment, water flows through a secondary sedimentation tank that allows both solid wastes and microorganisms to form clumps and settle out of the water that is being treated. This step in the process of wastewater treatment uses various types of bacteria to treat water. A part of the mixture of solid wastes and microorganisms that join together can be mixed with air and reused: this combination is called “activated sludge.” Activated sludge can be used to help improve crop soil or as a component of the process of making methane gas.

Once the water moves past this stage, it enters into the disinfection stage. During this part of the wastewater treatment process, chemicals like chlorine and sodium hypochlorite are added to the wastewater to remove harmful pathogens that cause cholera, polio, typhoid, and other diseases. Once the wastewater finishes its treatment, it can be returned safely to waterways in the vicinity where it will become a part of the natural environment and provide a home for fish and other types of water-based plants and animals.

Tertiary Treatment

These main steps of wastewater treatment are the most important, but there is a third step known as tertiary treatment. It is not as common as the other two steps, but tertiary treatment is capable of removing over 99% of all impurities from wastewater. Unfortunately, tertiary wastewater treatment is also relatively expensive.

Ensuring Safety During The Treatment Process

These main steps of wastewater treatment are critical for maintaining a safe natural environment. Now that you know more about wastewater treatment, it is important that you do everything in your power to help this process. By operating your wastewater plant in a safe way, you can help ensure you are running a more effective wastewater treatment plant, while keeping your facility, your employees, and the environment safe.

One of the best ways to ensure safety of the people and environment around you is to think through proper chemical storage. Our best advice is to start with the chemical you will be storing. You’ll be using different chemicals for at least five different reasons throughout the process, and each chemical requires specific storage guidelines be met.

To learn more about this process, we invite you to download our comprehensive guide to safe and effective wastewater treatment. 

Download Our Wastewater Chemical Guide

Topics: Applications