What Is The Wastewater Treatment Process?



Wastewater sludge can cause environmental devastation unless it is treated to remove harmful minerals, metals, pathogens, and organic contaminants. Treatment is a complex yet effective process that protects environments by ensuring that water is safe. Here’s what is involved to remove the most harmful elements so that water can either be safely disposed of, or treated further for reclamation and reuse. 

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1) Bar Screening

Large, coarse, and presenting a formidable barrier to debris, bar screens remove large objects and debris from wastewater. The bars are typically spaced between 1 and 3 inches apart, enabling them to capture chunks of plastics, metals, animal faeces, and other solids from the water. This stage is also known as ‘pre-screening’. 

2) Grit Removal

The headworks of wastewater treatment plants contain sand, silt, and grit. Grit can cause widespread damage to sensitive wastewater treatment equipment, so these abrasive particles are removed at the beginning of the process. Grit is sifted by a durable filter so that the sharp particles do not erode the system components. 

3) Primary Clarifier

Also known as sedimentation, the primary clarification process separates solids from the rest of the liquid to create a ‘sludge’ layer at the bottom of the treatment tank. During primary clarification, coagulation and flocculation agents change the chemistry of the water so that particles clump together, making them easier to separate and remove. 

4) Aeration

All wastewater contains microbial growths. By pumping oxygen into the tank, ammonia (NH3) is converted into nitrates (NO3), and this supercharges the microbes to consume contaminants. The process is very similar to aerating an aquarium, and enables a range of chemical processes that accelerate healthy bio-degradation. One of the most popular methods is ‘activated sludge’, which is where sludge is forced to create its own ammonia. 

5) Secondary Clarifier

After aeration, the water is full of thriving colonies of bacteria and biological growth. During the second clarification process, these are stimulated to clump together so that they can be filtered and removed or selectively destroyed. Known as ‘flocs’, these lumps of biological material can be recycled back into the system to continue the aeration process. 

6) Chlorination

Chlorine is deadly to bacteria, but only at precisely the right volume and pH. A large dose of chlorine removes any remaining bacteria such as E. coli and C. difficile, and is then dissolved into a harmless state. 

7) Water Analysis And Testing

Water is an active chemical solution, and successful water treatment involves altering the chemical balance. To ensure water safety, the pH level, ammonia concentration, and nitrate concentration must be checked. If they are not correct, the water is not safe to release into the environment. 

8) Effluent Disposal

If each stage has been followed correctly, the result will be water that is clean and healthy. As such, the effluent can either be disposed of or repurposed as industrial grey water for various non-potable applications.  

What Next?

Wastewater treatment is a crucial part of protecting the environment and conserving water use in industrial and agricultural applications. For more information about our water management products and services, please call 01778 562810 today.

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