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Incrementing G, Turbidity, and Gtheta
Dye Test
There are two bottles of fluid, one contains red dye and the other contains distilled water. Each bottle has one valve in front of it so that we can switch the flow from red dye to water and inversely. Then pipe is connected to a pump and then directly to the tube. This is where a variation occurs. When using the manufactured cap, we have to connect the inlet and outlet to the top of the tube. However, with the new tube, as in the picture, we connect the inlet to the bottom and the outlet to the top of the tube so that we can accommodate to the new cell-flush stage of the flocculator, which is flushing the tube from the bottom.
In order to the use the measurement device as a small tube comes out of the spectrophotometer meter, we put in a T-three-way connection near the end of the outlet. The tube from the machine in put into one of the open connection so that it can pump the sample into the machine. The rest of the output flow is put into waste.
Next, we open the spectrophotometer application in the computer. First, we need to establish a reference point. In other word, we have to define the zero value for the concentration of red dye. In order to do this, we pump into the sampling cell distilled water. This step needs to be done each time we open the application, and before running any test. When it is done, we need to create a set of standard for various concentrations. The purpose of this is to create data points for the program so that it can interpolate the test result using the same standard set. This step is done by pumping red dye solution at different concentration into the sampling cell. In our experiment, we use a set of four standards including clean water, or 0 concentrations, and 10, 20, 40 mg/L concentrated solution. Unlike the reference point, the standard can be saved as a file, and loaded later when we want to re-open the application.
After the preparation, we start running the test and collecting data. First, we open the red dye container while close the water container and turn on the pump. Thus, the red dye solution will be pump through the pipe and eventually fill up the tube. Then, we close the red dye valve and open the water valve at the same time as we collect data. As the cleaning begins, the water will flow into the tube, mixes with the red dye inside the tube and then outflow to the waste. The data will be collected near the exit of the outflow.
Initially, we started the dye test using the old cap for the small tube. However, as we collecting the data, no change was observed in the dye concentration of the tube. In other words, even thought the data showed that the concentration was decreasing, the fluid inside the sample tube showed little change in color, meaning that tube was not getting washed out at all. It was discovered later that because the entrance and exit inside the cap were horizontal and too close to each other, the flow of cleaning water actually came straight from the inlet to the outlet rather than dropped into the tube. Also, because we sampled near the exit of the outflow rather than inside the tube, the change in the data we collected might not have any relevance to the actual concentration inside the tube.
Realizing that the old cap was not effective, we switched back to the manufactured cap where the inlet is put vertically, which caused the flow to mix better inside the tube. We did nine in total tests by varying the flow rate and the initial concentration. The time scale during those tests was set as 1.2 second for each data point collected.
Also, as we observed, there is about 2 second of lagging time. It is the time it takes for the flow to travel from the container to the tube. We will need to take this time into account when using it for the programming of Process Controller.
Heat Test
The experimental setup was run using Process Controller software. A Process Controller method was modified so that we can compare the settled turbidity values for the case with the light left continuously on with the case of the light only turned on briefly at the end of the Settle state. It automatically looped through four states: "1- Clean Flocculator", "2- Clean Effluent Turbidimeter", "3- New Flow and Sample", and "4- Settle State." In this first sequence the turbidimeter was left on throughout states 3 and 4 to measure the settled turbidity throughout the first sequence. Then, the method was extended to replicate states one through three as states five through eight. A ninth state was added called "9- Measure Settled Turbidity." State nine was created to allow the turbidimeter to be turned off for the duration defined by set point "Off Time" in state eight and turned on for the "On Time" of two minutes. After the tests are run the data measured during the "On Time" in "9- Measure Settled Turbidity" and the last two minutes of "4- Settle State" were compared.
The raw water flow rate was 2 mL/s. The clay and alum flow rates are determined by the afore-mentioned flow rate, their respective tubing sizes, the stock turbidity or concentration, and a goal influent turbidity which was set at 100 NTU. Clay stock turbidity was set at 2800 NTU and alum stock concentration was 5 mg/L. A 12-inch glass tube was used in this experiment, and PVC pipe was fitted to cover the exposed part of the effluent turbidimeter sample tube to minimize the affects of ambient light in the lab affecting the turbidity readings.