Sampling Method
There is a hole in both of the sedimentation tanks located at the same level as the effluent launderer, from which it is possible to run a small tube to a turbidity meter with the assistance of a pump. The turbidity is then read in NTU and can be recorded through process controller in a Microsoft Excel file. This provides a continuous measurement; however, only one tank can be tested at a time. Because the conditions of the incoming water should not be changing significantly, it is assumed that this time delay from one tank's measurements to the next tank's measurements is not significant either.
The turbidity meter needs to be cleaned out before any measurements are taken though, since flocs tend to build up in the small testing unit. If left uncleaned, the turbidity will be far too high, and will not reflect the current state of the tanks.