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I have conducted a literature review of scientific journal articles and research reports on the properties of PACl and alum as coagulants for water treatment. Specifically, properties of interest that I focused my research on were viscosity and solubility, both important factors for mixing solutions of either material. Slightly later on in the semester, we carried out another literature review, this time with a focus on mixing systems. We found a lot of material that relates to using impellers for mixing. We found that impellers may be viable for large tanks. From the literature we realized that typical impeller mixing revolution rates were on the order of 300 rpm. This type of rotational speed is achieved using electric motors, something that AguaClara does not have access to. However, information was found that may be useful to future teams.
I developed the design for the mixing reactor (the "double bucket") that our team tested early on in the semester. One benefit of using this mixing reactor is the fact that no matter what the inflow is (even if it is zero) , the coagulant will stay saturated. In addition, this design has the potential to achieve very high concentrations of coagulant (upwards of 300 grams/liter). This is an important benefit as it would allow operators to achieve necessary levels of coagulant concentration during treatment operations with smaller batch sizes.
Unfortunately, we discovered that the head pressure necessary to push the coagulant solution through the pores was to high to allow for reasonable use in AguaClara plants. If we were to increase the pore size, undissolved granules of coagulant could potentially make their way into the stock tank. We later discovered that this mixing reactor was not pertinent to the coagulant PACl. PACl granules are quite easy to dissolve as they are very fine. The problem with PACl was the concentration gradients that PACl solutions would form.
Together with my teammates, I worked on the 'upflow' mixing reactor design and testing. I worked with my teammates on the 'simple stirrer' design. I, along with my teammates, created a MathCAD file that calculated the potential energy difference between a fully homogenized solution of PACl and an unmixed solution of PACl (a solution with a strong concentration gradient). This MathCAD file also calculated the energy input of the stirrer given the dimensions of the stirrer.
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In addition to the above, I have helped my team create reflection reports, the teach-in, final report, final presentation and other course related documents. I also helped proofread documents that other team members composed.
Our team only had three members. Because of this, we almost always combined our efforts worked towards the same goals at the same time. Every team member worked extremely hard this semester and certainly and each member certainly was a huge benefit to the team.