Biological Helpers
Activated sludge treatment can remove up to 90 percent of pollutants from wastewater in only one step, without going through the trickling filter, clarifier, biodisc, clarifier sequence. Its introduction into the DeKalb plant helped to handle the increasing demands made by the growing population of our area.
Alternate Route for Secondary Biological Treatment
In 1998, the DeKalb Sanitary District added this newer type of secondary treatment process to its plant, providing an alternate route for the wastewater to move through the cleanup process. This increased the amount of sewer water that the plant could treat, which was necessary because of the great increase in the population of the area.
Activated Sludge
In the Advanced Secondary Treatment section of the plant, wastewater is combined with bacteria that are kept in suspension with fine air bubbles in tanks called "aeration tanks." The mixture of nitrifying bacteria and air bubbles is called "Activated Sludge."
Aerobic Bacteria Eat Pollutants
A mixed population of many different kinds of organisms (like those found in nature) use the organic materials in the wastewater as their main food supply. These "aerobic" bacteria need oxygen to do their work, and the rich supply of oxygen in the activated sludge facility makes them happier, healthier, and more efficient.
Secondary Clarification
After the bacteria have consumed both organic matter and ammonia nitrogen, the result is carbon dioxide and a bigger population of bacteria. The mixture is separated in clarifiers. Then the wastewater moves on to the next process, while the activated sludge is returned to the head of the aeration tank to begin the feeding process again.