Sampling Method

Overview

Alum is used as a coagulant, the dose can be set using process controller. Raw water running through flocculation tank can be sampled at any desired location. Sampling lines run to turbidimeters from three mobile 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 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 therefore necessary to determine the best alum dose for each day of testing to ensure the formation of good flocs.

Tube settlers

Tube settlers are used to test effluent turbidity at different locations. The tube settlers were designed to mimic the sedimentation tank that would traditionally follow the flocculator. Tube settlers were chosen because they provide an inexpensive way to sample and create a minimal disturbance within in the tank. Using this method, different locations of the tank can be sampled. Data gathered can be used to assess how each stage of the tank is affecting the final effluent turbidity. The three glass tube settlers used were of 60 cm length and 2.5 cm diameter. A peristaltic pump was used to transport the water to the three turbidimeters.

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