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A Breakdown on Tertiary Wastewater Treatment

What is Tertiary Wastewater Treatment?

What is tertiary wastewater treatment? Let's examine the process and operation of tertiary wastewater treatment plants and the modern progression of wastewater treatment.


The majority of tertiary wastewater treatment systems include at least two major treatment processes. Secondary wastewater treatment can also be used, but may require additional methods. Primary wastewater treatment removes 50% to 70% of the suspended solids from wastewater.


This uses physical processes such as filtration and settlement to remove grit and debris. To break down suspended and dissolved biosolids, secondary wastewater treatment uses biological processes such as activated sludge and aeration.

Tertiary wastewater treatment is the third and more rigorous level of treatment. Secondary and primary treatment usually makes wastewater safe enough to be released into the environment. Tertiary wastewater treatment can purify water to make it safe for reuse in water-intensive or drinking water processes.


Some wastewater treatment plants do not use tertiary wastewater treatment. Secondary and primary treatments can often be sufficient for multiple purposes. Tertiary wastewater treatment is used by those who have to maintain a higher standard of cleanliness in order to comply with the strict standards for water reuse, particularly in public water supplies. When facilities have to discharge water into fragile aquatic ecosystems, such as estuaries or slow moving river waters, tertiary wastewater treatment can be a benefit.


Tertiary wastewater treatment works better than either primary or secondary wastewater treatment to remove unwanted color from wastewater. This is especially important in communities with textiles industries and industrial pulp and paper production.



The Process of Tertiary Wastewater Treatment

In the process of tertiary wastewater treatment, it is often a combination physical and chemical processes that remove microbiological contaminants from wastewater. This usually involves additional disinfecting treatment and filtration processes. Sometimes, additional specialized treatments may be required such as lagoon storage, biological nutrient removal, and removal of nitrogen and phosphorous.



Tertiary Wastewater Treatment Filters

There are many materials that can be used in tertiary filtration. Filters can contain activated carbon and sand, as well as fine woven cloth. There are many types of filters available, including drum filters, bag filters, and disc filters.


  • Bag filters: Bag filter are perfect for wastewater treatment plants who need to reduce contaminants to a certain micron rating. You can make them from felt or mesh for use as depth media. They can be used with a variety of equipment and treatment plants.

  • Drum filters A drum filter is a drum that has a filter cloth around it. The central drum is used to send wastewater into the filter. The drum houses media that separates the water from the solid particles. After the drum is turned, the filtered water flows through the media to the tank. To ensure that the media components continue to function after the separation is completed, you can backwash them.

  • Disc filters A disc filter is a combination of a central drum and multiple discs with cloth filters. In an inside-out flow, gravity pushes wastewater into the filters from the drum. On each disc, media are mounted to separate the solid particles from the liquid. After the media have become saturated with particles, clean water is pumped into a collection tank.



Disinfecting - Tertiary Wastewater Treatment

Tertiary disinfection can take many forms:

  • Chlorine treatment.Chlorine, a disinfectant that is cost-friendly, simple to use, and highly effective, is one of the most popular in wastewater treatment. To kill microorganisms such as bacteria and viruses, wastewater treatment plants can add chlorine to the wastewater. Chlorinated wastewater must be dechlorinated before it is released into the environment. However, chlorine can cause harm to aquatic ecosystems. Chlorine can react with organic material to form potentially cancer-causing compounds such as trihalomethanes or mutagen.

  • Ultraviolet treatment: UV light is used in tertiary disinfection. The UV light sterilizes microorganisms and flows through wastewater. Although ultraviolet light doesn't kill bacteria and viruses, it makes them infected impossible to spread to humans or animals. Because any residual organic matter may protect the microorganisms against the UV light, it is necessary that the effluent has undergone a thorough treatment. Lamps also need to be maintained at a high level.

  • Ozone treatment Another method is to use Ozone - an organic compound made by using electricity to add another oxygen atom to the standard diatomic O 2 - to disinfect. Ozone is extremely reactive and can kill most microorganisms that it comes in contact with. Ozone is safer than chlorine as plants can produce it on-site, rather than store it for long periods and risking toxic leakage. It will not create harmful byproducts in water. However, the equipment can be quite costly to maintain.



Tertiary Wastewater Treatment Discharge

After the wastewater has been treated, it can be discharged back into the environment. Many municipalities have strict regulations regarding the discharge of treated water. Tertiary wastewater treatment should suffice to meet these standards and protect human health.



Reuse after Tertiary Wastewater Treatment

Tertiary wastewater treatment is a process that water treatment plants employ to make it safe for human consumption. The water is safe to drink after the tertiary wastewater treatment. Tertiary treated water is suitable for many operations, including industrial and manufacturing processes, as well as utilities cooling, and agricultural practices such irrigation.


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