Secondary TreatmentThe actual biological treatment process takes place in tanks known as aeration basins. The result of this process is a reduction of the dissolved and colloidal matter. Biological treatment involves a variety of ‘bugs’. The aerobic ‘bugs’ or microorganism population, in the presence of oxygen, uses the organic material to sustain their life processes of growth, metabolism, and reproduction. It is therefore the priority of the wastewater operator to maintain conditions that are favorableto these ‘bugs’. Motorized aerators and mixers supply the needed aerobic conditions.
The aeration process results in a high concentration of biological solids in suspension. This suspension then goes through a liquid-solids separation process. This sedimentation process occurs in what is known as a clarifier.
The end result of this process results in the clear water known as supernatant or effluent.
The Covington WRF uses one aeration basin (w/mixers and aerators). One of three clarifiers used in the settling process is shown above.