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This sampling method for testing raw water at the Pilot Plant has been used for several semester's research. Alum or PAC is used as a coagulant and the dose can be set using process controller. Raw water running through flocculation tank can be sampled at any desired location by placing the tube settlers there. Sampling lines run to turbidimeters from the tube settlers. The tube settlers mimic sedimentation. Additionally a sampling line runs from the raw water inlet to a turbidimeter. Turbidity data is stored in a excel spreadsheet using process controller.
Alum Coagulant Dosing
Because the pilot plant takes water directly from the stream, environmental conditions change all the time and affect the incoming turbidity to the plant as well as the chemical composition of the particles causing turbidity. It is incredibly important to determine the best alum or PAC dose for each day of testing to ensure the formation of good flocs and collect appropriate data. The alum dose can also be related to the plant's PAC dosage using the relationship 1 part per million is equivalent to 0.182 mg/L.
Tube Settlers are used to mimic sedimentation before the turbidity of water in the flocculator is measured. They can be moved to different locations along the flocculator in order to examine effluent turbidity at various stages of flocculation.
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