Unformatted text preview: tewaters, the primary buffer is the bicarbonate carbonate system. Step 3:C o a g u l a t i o n and Flocculation The chemicals cling to substances like dirt and bacteria that are in the water. These particles stick together to form larger particles which look like small brown tufts of cotton wool. This process is called flocculation and the brown particles are called flocs. The addition of dirt and bacteria to water are colloidal in nature. The two primary ways of destabilizing are Coagulation and Flocculation. Coagulation reduces the net electrical repulsive forces at particle surfaces by electrolytes in solution while flocculation is aggregation bridging between particles. by chemical Step 4:S e d i m e n t a t i o n The water and floc passes into tanks. The floc settles to the bottom and is removed from the water. These tanks may be circular or rectangular. They are often called clarifiers. Sedimentation is the removal of solid particles from a suspension through gravity settling. In water treatment, sedimentation is used to remove particulate matter, flocculated impurities and precipitates which are formed in operations such as water softening or iron removal. In wastewater operations, it is used to remove both organic and materials which are settleable. inorganic Step 5:F i l t r a t i o n
After sedimentation, the water flows through filters. Filters are made of layers of sand and gravel. Sometimes other substances such as anthracite coal, and activated carbon are used in the filter. The filters are used to remove any particles remaining in the water. Filtration = is an operation to separate suspended matter from water...
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- Winter '11