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  • Writer's pictureIn-Pipe Technology

Why Tertiary Wastewater Treatment Is So Important

When it comes to fully understanding the process of how communities get clean drinking water, how sewer systems stay maintained, and how public bodies of water don't get contaminated and become toxic for animals and humans alike, you must first have a basic understanding of why tertiary wastewater treatment is so important to begin with.

Why drink boxed water when communities can have clean drinking water through the tertiary wastewater treatment process? When done properly, and by professionals, tertiary wastewater treatment can mean a cleaner environment for animals which means a better ecosystem for humans. So how is this accomplished and what is the process of tertiary wastewater treatment in our local communities and municipal cities? We'll walk you through the basics so that you have a better understanding of it all.

There are three main stages of treatment for wastewater (or sewage) that include the primary treatment, the secondary treatment, and then the tertiary wastewater treatment. Tertiary wastewater treatment is used to improve effluent water quality after the primary and secondary stage of wastewater treatment. After the tertiary wastewater treatment step in the process, the water can then be safely released into the environment (water bodies such as rivers and lakes) but only after the tertiary wastewater treatment process. It can then be used for industrial purposes, agricultural uses, and in most cases, for domestic purposes.

Tertiary Wastewater Treatment

To be clear, even after the wastewater has reached the tertiary wastewater treatment stage, it still contains suspended matter and fine particles. It also contains a high amount of nutrients like nitrogen and phosphorus, as well as microbes and an odor. Different methods can be used to remove any contaminants or properties from the wastewater during the tertiary process.

Filtration is the first stage in the tertiary wastewater treatment process, which helps to remove suspended matter from the wastewater. This is usually done using sand filtration. Sometimes residual toxins can be found in wastewater and activated carbon is used to absorb these toxins and then is removed from the wastewater.

Some fine particle matter can still be found in wastewater after the tertiary wastewater treatment filtration step. In cases such as this, the wastewater is then treated further by being transferred to lagoons equipped with filter feeders. Further removal of fine particle matter is possible in the lagoon's biologically rich environment. However, the wastewater could still contain high levels of nutrients, which means that it is not potable.

High concentrations of phosphorus and nitrogen are common in wastewater. If untreated, this can lead to excessive illness and even death. The amount of oxygen in the wastewater from bacterial activity is reduced by the death of algae, which makes it less suitable for aquatic life. It is important to reduce the nitrogen and phosphorus levels with tertiary wastewater treatment before wastewater is released into water bodies.

Both nitrogen and phosphorous can be removed by biological processes that involve different bacteria. Ammonia, which is nitrogen, is first oxidized into nitrates. Then nitrates are converted to nitrogen gas. However, phosphorus can also be removed biologically with chemical precipitation using salts of iron or aluminum when implementing the tertiary wastewater treatment process.

A high amount of phosphorus can be accumulated by bacteria, and the biomass can also be used as fertilizer. The phosphate-rich sludge, which is formed during chemical treatment to remove phosphorus, has good value as fertilizer. Before releasing the wastewater into the environment, the final steps of tertiary wastewater treatment are to remove any unwanted microbes and also eliminate odors.

The tertiary wastewater treatment stage is crucial for the effectiveness and efficiency of the disinfection process. It is important that wastewater is clear and not cloudy. There are many disinfection agents that can be used, depending on the wastewater condition (pH and clarity), hence why implementing the tertiary wastewater treatment process.

The most popular disinfection agents are chlorine, ozone, and ultraviolet (UV) lights. Each has its advantages and disadvantages. The effectiveness of chlorine as a disinfection agent has been proven time and time again. But, prolonged use and unregulated dosages may lead to the formation of chlorinated-organic chemicals from the chlorination residual organic matter in water. These compounds can be carcinogenic without tertiary wastewater treatment.

If the water is going to be used for drinking, it is necessary to de-chlorinate it using the tertiary wastewater treatment process. The ultraviolet light treatment for disinfection doesn't leave behind any compounds or residues in the water, but it is important that the wastewater be clean for it to work.

For long-term UV light usage, it is important to maintain the equipment and lamp properly. Ozone can also be used as a disinfection agent. It doesn't need to be stored and can be made on-site with the appropriate equipment. The main cause of wastewater odor is the release of gases such as hydrogen sulfuride from wastewater treatment plants.

Carbon reactors can be used to regulate the levels of hydrogen peroxide and calcium nitrate. It can be used to reduce the odors in wastewater and manage hydrogen sulfide. After the tertiary wastewater treatment step, the wastewater can be allowed to flow into the environment for further reuse. This, of course, is the ultimate goal.

For more articles like this one on subjects like tertiary wastewater treatment, sewer odor control, and FOG control programs, click here.

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