Collective Conclusion

Group Analysis

The original vision for our experiment was simple: attempt to make a low-budget, gravity-fed sand filtration system and check how well it filtered a solution of water. While water filtration ultimately has a widespread number of uses, our experiment focused on plants as agriculture is one of the largest uses of fresh water in the nation and is a common cause of water shortages (“U.S. Freshwater”). Designing a filter that would facilitate the process of inexpensively turning water currently considered 'waste water' into water usable for agriculture would theoretically issues caused by water shortages.

The experiment was broken down into three parts for each of the respective sciences: Physics was in charge of designing a filter and testing its efficiency — a very real-world concern. Chemistry was tasked with measuring how the filtration system altered the concentration of a baking soda solution. And Biology had arguably the most important role: testing how well aquatic plants responded to the filtered water versus the unfiltered solution.

Experiment Summaries

Physics

Research Question:

How does time affect the flow rate of water through a gravity-fed sand filtration system?

Hypothesis:

The original hypothesis of the experiment was that flow rate will gradually decrease as time increases.

Conclusion:

The trendline appears to support the experiment’s original hypothesis that as time increases the flow rate of the filtration system will decrease. This is, of course, because the supply of water was poured in once rather than being kept steady over time. Regardless, the results are not very accurate and as such the trend line fits through very few data points. This could be improved by taking both more measurements and recording the volume of water filtered to a higher degree of accuracy. It would also be helpful to test how the amount of solution put into the filter affects the total time for filtration or to run more trials for the current amount of solution to record more accurate data.

Chemistry

Research Question:

How effective is a sand filtration system in filtering baking soda, NaHCO3(s), from a 0.5M baking soda solution, NaHCO3(aq)?

Hypothesis:

Filtering a baking soda solution, NaHCO3(aq), through a sand filtration system will decrease the concentration of baking soda solution, and thus be an effective filtration system.

Conclusion:

Refuting the hypothesis, the molarity of the NaHCO3 solution increased. This was perhaps due to the mixing with sand and the passing of the small NaHCO3 molecules through the filter. Although there wasn’t any significant conclusion made with respect to the molarity of the NaHCO3 solution, a marked difference was noted in the pH of the solution. The pH of the solution decreased from 10.36 to 9.40. This difference explains that although the filter did not necessarily filter any of the NaHCO3 solution, it did make the solution more acidic, and thus, more neutral.

Biology

Research Question:

What is the effect of the presence of the chemical Sodium Bicarbonate (NaHCO3) on the amount of oxygen or photosynthetic output released by the aquatic plant, Cryptocoryne wendtil over time, and how does the variation of this effect show the effectiveness of the filtration process?

Hypothesis:

The presence of the chemical Sodium Bicarbonate would increase the amount of oxygen or photosynthetic output released by the aquatic plant, Cryptocoryne wendtil. Also, the more the time the plant stays in the environment, the more oxygen will be released. This is predicted due to the fact that plants produce oxygen over time and Sodium Bicarbonate can increase oxygen levels. Similarly, the filtered solution is projected to display a median oxygen level, assuming the filtration process affected the presence of Sodium Bicarbonate in the sample procured.

Conclusion:  

In conclusion, the results and data were expected and followed the initial hypothesis precisely. However, when the chemical solution was filtered, there was more oxygen present. This may have been due to oxygen being present upon the rocks and materials used during the filtration of the liquid when the Physics portion of the project/experiment was conducted. All in all, however, the change in oxygenation prior to and including the addition of the aquatic plant Cryptocoryne wendtil changed very similarly in all three samples. This indicates that the filtration system showed no significant difference in the rate of the photosynthetic output of the plant. This could signify a limited experiment- and there were, indeed, issues within the experiment that could indicate a potential for error- but it is also possible to conclude that the filtration system was neither a hindrance nor a help to the welfare of the vitality of the aquatic plant.

General Conclusion

As it can be seen from each science's respective conclusions, the experiment did not go according to plan. The filtration system itself leaked too much of its own sand into the final solution, masking any possible changes by this unexpected change.

So why did the experiment not go according to plan and how could it be improved? After much talk, we have come to conclude that the filter worked too quickly and the water did not pass through enough sand. Perhaps the largest issue, though, was the abundance of sand which escaped through the filter into the collection beaker. Both of these issues could be fixed by making a slightly more complex pipe design which would take more time but allow the extra sand particles to settle out first.

The filtration of sodium bicarbonate was a pressing issue that was derived from the reported issues that sodium, especially with bicarbonates, causes in soils. The most detrimental effect being that soil treated with water containing high sodium content will breakdown the soil. Moreover, the soil will become “hard and compact when dry and increasingly impervious to water penetration” ("Irrigation Water Quality Standards and Salinity Management Strategies”). Through distillation, it was found that the concentration of the sodium bicarbonate did not decrease, but rather tended toward neutral pH through acidification.

Of course there are real world sand filters that work, however the effectiveness of those sand filters is more in their ability to filter biological living hazards instead of contanements. After all, for the millions of people around the world who do not have access to industrially filtered water, biological dangers are very real when drinking from local water sources.According to the CDC (Center for Disease Control and Prevention), common sand filtration with a biological layer have shown 99.98% protozoan, 90-99% bacterial, and variable viral reduction in lab effectiveness studies. Most sand filters around the world are used for that very purpose, to filter biological hazards.  We tested our filter for the filtration of Sodium biCarbonate, estimated a rough optimization for best volumetric flow out, and at the end concluded that the filter did little to to alter the amount present per mL and more to neutralize the water to a more ideal pH (7).  

But are there other real-world uses for our defunct sand filter/acidifier? Yes…! Maybe. It has been shown that our low-budget sand filter is capable of releasing sand into a solution. Because our solution was basic and the sand acidic, this meant that our final solution was at least somewhat more neutral than the unfiltered solution. Of course, these results were only slightly different and are yet to be verified. Further experimentation is necessary. The filter constructed, unfortunately, may make little to no difference on the welfare of plant life, assuming its job it to remove pollutant. The change in water oxygenation was not greatly affected by the use of the filter, nor was the photosynthetic output of the plants significantly altered by the filtered solution. However, issues with the filter itself could be rectified on a larger scale and could yet be made to support the betterment of the environment.

Approximate Hours

Alec Emser: 15 hours

Arber Muharemi: 17 hours

Gabriel Orion Johnston: 19 hours

Juan Manuel Alzate Vanegas: 22 hours

Emily Basara: 18 hours

Samantha Jones: 18 hours

Works Cited

Distillation Apparatus. Digital image. Rhodium. Erowid, n.d. Web. 1 Mar. 2015.

Fipps, Guy. "Irrigation Water Quality Standards and Salinity Management Strategies." (n.d.): n. pag. Texas A&M Agrilife Extension. Texas A&M University System. Web. 27 Feb. 2015.

Perlman, Howard. "What Is Most of the Freshwater in the U.S. Used For?" What Is Most of the Freshwater in the U.S. Used For? Water Science Questions and Answers, from the USGS Water Science School. United States Geological Survey Water Science School, 14 Mar. 2014. Web. 15 Feb. 2015. <http://water.usgs.gov/edu/qa-usage-freshwater.html>.

"Fluid Volumetric Flow Rate Equation - Engineers Edge." Fluid Volumetric Flow Rate Equation - Engineers Edge. Web. 4 Mar. 2015. <http://www.engineersedge.com/fluid_flow/volumeetric_flow_rate.htm>.

"Slow Sand Filtration." Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 2 May 2014. Web. 4 Mar. 2015. <http://www.cdc.gov/safewater/sand-filtration.html>.