Oneonta Utilities Board

Wastewater Treatment

Wastewater treatment is accomplished by using a Sequencing Batch Reactor, or “SBR” treatment process to clean the water. When the wastewater reaches our treatment plant, it immediately flows through a static screen to remove large items such as trash, plastic, rags, sticks, and other similar items. It is then piped to one of three large storage lagoons where it is held until it can be treated in the SBR.

The SBR has five main operational steps that it goes through in order to treat the wastewater. The first step is the “Fill” cycle, which is exactly what its name implies. During this cycle, the reactor is filled with raw sewage to its maximum operating capacity. We have two reactors that operate on a staggered time schedule to allow for the maximum operational efficiency. Each reactor is a large concrete tank in which the wastewater treatment occurs.
Once the reactor is full, it enters the “React” cycle. During the React cycle, large amounts of air are added to the wastewater in order to activate the microorganisms that stabilize the wastewater through chemical reactions of oxidation and synthesis.

Once the microorganisms have had time to react, the air is turned off and the reactor enters the “Settling” cycle. In the Settling cycle, the heaviest solids settle to the bottom of the reactor and the cleanest water is left on top.

After enough time settling, the water is clean enough to enter the “Decant” cycle, during which the cleanest water from the top is removed through a floating mechanism called a “decanter”. When the clean water has been removed from the top of the reactor, the process enters the final step, known as “Idle”. During the Idle phase, the water from the bottom of the reactor, which contains the heaviest materials known as sludge are pumped out of the tank. Some of this sludge is pumped back into the reactor later and some of it is pumped to a holding area until it can be reused or disposed of.

The clean water that was removed during the Decant cycle is purified even more by flowing through a filtration system that was installed in 2006. After being filtered, our water is disinfected using chlorine. Then the clean, disinfected water can be returned to the environment.