What Is the Wastewater Treatment Process?
Monday, August 10, 2020

Wastewater treatment is a necessary process done to protect both human health and the environment. According to the United States Geological Survey (USGS), untreated wastewater harms fish and other wildlife, leads to oxygen depletion, and limits water usage.

But how is exactly is wastewater treated?

Keep reading to learn more about the 8 steps of the wastewater treatment process.

1. Screening for Large Items

The process begins with equipment screening incoming wastewater for any large items, including wood fragments, rags, plastics, and grease. This is done to prevent damage to pumps, valves, and other facility equipment.

Materials are washed, pressed, and then sent to a landfill.

2. Screening for Grit

After the initial screening, the wastewater then moves to a grit chamber. There, equipment screens the water again, but this time for finer materials, such as gravel and sand.

Anything found is also sent off to a landfill.

3. Primary Clarifier

After the screening, circular tanks known as clarifiers separate the wastewater from solid organic material.

Solids, known as sludge, sink to the bottom of the clarifiers and are then pumped out. Any grease or other materials at the top are also skimmed off. The sludge is regularly emptied and used as fertilizer.

4. Aeration

In rivers and lakes, bacteria and other microorganisms naturally break down organic materials. This process, however, takes years.

To expedite it, wastewater treatment plants pump oxygen into tanks in a process known as aeration. This encourages the growth of bacteria through the conversion of NH3 to NO3.

Bacteria then efficiently break down any organic material present.

5. Secondary Clarifier

After aeration, wastewater flows into secondary clarifiers where it is again treated for any remaining solids.

These remaining solids are smaller and called activated sludge. They primarily consist of activated bacteria.

At this stage, the wastewater is over 90% treated.

6. Disinfection

As aeration substantially increases the presence of bacteria, disinfectant is then added to kill any that remains.

Chlorine is one type of chemical used, but UV disinfection and ozone are becoming more popular.

Testing then checks the chemical levels of the water and ensures that it can safely be sent into the environment.

7. Water Analysis and Testing

Wastewater is tested throughout the entire sewage treatment process, but one final comprehensive test ensures that the water is ready to leave the wastewater treatment plant.

Tests can look at a variety of parameters, such as chlorine levels, pH level, and dissolved oxygen.

8. Effluent Disposal

After testing finishes, the water is ready to return to the environment. This treated liquid waste is known as effluent.

If a water treatment plant discharges effluent before it meets certain regulations, it may be subject to a fine. The operator in charge may also face legal ramifications.

The Wastewater Treatment Process: An Essential Operation

The wastewater treatment process is important for both human health and the wellbeing of the environment.

Wastewater enters treatment plants and goes through a series of steps. After the facility removes solids and treats the water, it then returns into the environment as treated effluent.

Contact us today for help with any of your wastewater management needs.