What is Wastewater Treatment Plant?

Water is a renewable resource, but sometimes it needs to be treated to use it again. Water treatment is the process of turning used or dirty water into something that can be used for some other purpose. Wastewater treatment is a complicated process and can only be done effectively in a wastewater treatment plant. This treatment removes all the unwanted particles and turns them into environmentally acceptable water.

Pre-treatment

Pre-treatment is the process that removes all of the easily removable particles from the wastewater. The particles that are removed during pre-treatment include fats, oils and greases, sand, gravel, rocks, rags, feminine hygiene products, and other larger solids that can easily be filtered out.

Primary Treatment

In this stage, the wastewater flows through the primary clarifiers that have large tanks. These tanks are large so that the sludge can settle, and all of the floating material like grease and oils rise to the surface where they can be skimmed off. They have mechanical scrapers that help to collect sludge into a hopper.

Secondary Treatment

The secondary treatment is the stage where human waste, food waste, soaps, and detergents are broken down and composted using an aerobic biological process. After it is composted, it goes through a series of filters that clean out other small particles such as bacteria and algae. There are different kinds of filters including trickling filters, biological aerated filters, and many more. Trickling filters are where the settled sewage liquor is spread onto the surface of a deep bed made of carbonized coal, limestone chips, or specially fabricated plastic media. The liquid is made to pass through the purifier to filter out all the biological films such as bacteria, protozoa, and fungi. The sand filtration removes residual matter, and activated carbon filtration removes the presence of toxins.

Nutrient Removal and Disinfection

Wastewater contains some nutrients such as nitrogen and phosphorus that are harmful in large doses. Nitrogen is removed from the water using oxidation that converts it to nitrate and then into nitrogen gas that is removed from the water by releasing it into the air. Phosphorus is removed by using chemicals such as salts of iron or aluminum. The final step in wastewater treatment is the disinfection stage, where chlorine or ultraviolet light is used to disinfect the water. With this last step, the water is transformed from a contaminated liquid into reusable water.