Week 1
In lab this week, our group decided to do the water filtration project. Groups had to choose their top choices, and only select ones were able to get top decisions. The water filtration project is to be aimed for consumption by farmers over in Thailand who do not have access to clean water. The specifications are that the water filtration devices that is being made is able to purify around 20 liters per day, with a filter life of about 500 liters before it is to be replaced. Our group got together and brainstormed ideas after completing the specifications chart. The most important specifications are that the water is purified to a pH around 7 and all harmful as well as visible debris is removed. Also the water container must carry at least 2 liters, but ideally 3 liters.
The best idea we had was a pump filter where the user pulls the water up through a syringe like device. A rough sketch is below.
The only way this plan falls short is the carrying of 3 liters.
UV filtration- the use of electricity to kill all harmful bacteria. Downside is will not remove dirt.
Chlorine- Effective in killing bacteria, but water will have a bad taste. The group consensus was that people would rather drink dirty water that tasted good than clean water that tasted bad.
Sand Filter- Effective in removing bacteria and dirt; however, it is not very portable since the layers of sand have to be perfectly set. The filter works through layers shown below. Each layer filters out dirt and bacteria, and would be effective for the water in Thailand.
Activated Carbon- This is used inside brita filters, and will most likely be the route chosen for our design supplemented by something to keep the dirt out of the filter because the activated carbon does not get rid of that.
The concept tree was made to outline all of the possible ideas, and what it specifically does to filter water.
The best idea we had was a pump filter where the user pulls the water up through a syringe like device. A rough sketch is below.
Week 2
This week was dedicated to researching different ways to filter water, and finding the best method.
UV filtration- the use of electricity to kill all harmful bacteria. Downside is will not remove dirt.
Chlorine- Effective in killing bacteria, but water will have a bad taste. The group consensus was that people would rather drink dirty water that tasted good than clean water that tasted bad.
Sand Filter- Effective in removing bacteria and dirt; however, it is not very portable since the layers of sand have to be perfectly set. The filter works through layers shown below. Each layer filters out dirt and bacteria, and would be effective for the water in Thailand.
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| Sand Filter |
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| Concept Tree |
Week 3
This week was dedicated to determining which five concepts are the most feasible for the water filter. After considering over 12 concepts, the five we determined were the best for filtration based on the scenario are activated carbon, chlorination, biological film, cloth filtration, and sand filtration. After using a Pairwise Decision Matrix to determine which the best were, the final results revealed that the cloth filter and the activated carbon filter are the most feasible options. It has been decided by the group that our final design will incorporate activated carbon to filter macromolecules, while a cloth with small pores will disinfect the water by capturing bacteria. E. Coli is a common bacteria found in the water in Thailand, the size of the bacteria being on the order of several microns. By using a cloth that has pores of only one micron, the bacteria can be captured, thereby disinfecting the water. These two filtering agents are planning to be incorporated in a gravity-based filter, but the final design is yet to be decided upon. Some ideas have included a filter attached to a belt so that the farmers can carry it easily, in addition to an armband attached to the filter which the farmers can strap to their arm. Finally, another design is simply a cylindrical container which will house water which will be filtered using gravity. One important aspect of this project is the cost-efficiency of the filter. The team has researched several sites for the filtering materials in order to determine the cost. Seen below are the cloth and activated carbon (including how activated carbon works) materials which are going to be purchased online, in addition to the links to these materials below. The cloth is a felt filter which has pores of 1 micron. A 36” by 72” sheet is only $18.50, while 40 oz. of activated carbon is only $15.49. While this is over the five dollar cost intended for the filter, the amount of material purchased is able to be used for several filters.
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| Type of cloth to filter out large bacteria and dirt |
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| Activated Carbon we plan on purchasing. |
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| This picture Shows one of the pores in activated Carbon. When all the pores are full the carbon needs to be replaced |
Week 4
In Week Four Groups got together to finalize which design concepts and ideas they were going to use while building prototypes. Our group decided that we were going to use a system of nano cloth filtering as well as activated carbon. We decided that since activated carbon and the botch filtering both have a very good capacity to remove all types of biological chemicals and other elements from the water, as well as being cheap, that they would be the best types of filtration. This week we created a 3D creo model of the filter that we wanted to use, maximized cost efficiency for the different types of materials we were going to use, and completed the design proposal write-up. The design that we came up with is similar to that of a normal water jug used for water, but with a small cylindrical center that has cloth covering one end, is filled with activated carbon, and has another cloth filter on the other end. We decided that the best way to contain the water would be a larger reservoir under the filter, with a small valve, similar to that of a Gatorade Jug used by athletes.
Week 5
This week we started the design process. Our intention is to use activated carbon and filter cloth that has small enough pores to filter out all dirt and bacteria. Using these materials, the plan is to make a basic filter using a water bottle, activated carbon, filter cloth, and duct tape. We will put activated carbon between two pieces of cloth, and tape the cloth to the outside of the water bottle, packing the activated carbon in between the two cloths. Using water from the Schuylkill river to pour through our filter prototype, we will determine whether the filter is successful in eliminating waste. The design and testing of the prototype will be done in week 6. We plan to utilize the water lab available to us to test the filtered water to determine whether the filter is effective on the micro scale. We will evaluate the results from that point, and determine whether the filter components are adequate to be used in the final design. The figure below is the filter designed. There is 100 grams of activated carbon held in by a filter cloth along the bottom. Also there is a filter cloth at the bottom of the nozzle.
Below is the schuylkill river water test. It showed that the starting pH was 7.2, the salinity was 174ppms and the dissolved solids was 2.59 ppm. The coliform colony count was 170. The salinity is what is most worrisome, but the stats are actually not that bad. The water can actually be drunk.
Below is the test of the filtered water using 300 g of activated carbon, and two filter cloth layers. The tests were not good enough because there are still 13 coliform colonies.
Week 6
This week was used to acquire a sample of water from the schulykill river, and then test the sample in the water lab. The water sample was tested for pH, bacteria concentration, and debris concentration. The test turned out to show that the water is relatively good. However, in the water lab was a sample of water from Thailand. Since our water filtration device is to be utilized in Thailand, we decided to use that water to test our prototype.
Below is the schuylkill river water test. It showed that the starting pH was 7.2, the salinity was 174ppms and the dissolved solids was 2.59 ppm. The coliform colony count was 170. The salinity is what is most worrisome, but the stats are actually not that bad. The water can actually be drunk.
Week 7
We returned to the water lab this week to test our prototype with the Thailand water. The filter worked in terms of visually getting rid of debris, but it did not filter enough bacteria. To solve this we plan to put a double chamber, so that the water is filtered twice. This should work because the filter cloth is small enough to catch the bacteria in certain direction. It is like a stick going through a hole. If the stick is straight up it will fit through, but if it is sideways it will get stuck. The double filter should work because the water is going through at a slower rate, and the filter has a second chance to catch the remaining bacteria.
Below is the test of the filtered water using 300 g of activated carbon, and two filter cloth layers. The tests were not good enough because there are still 13 coliform colonies.
Week 8
This week was dedicated to researching and redesigning for the final product. The filter cloth needs to be used more than in the previous design because the cloth is able to catch smaller bacteria than the carbon can. Also the carbon will be packed in tighter because we want the water to flow through the carbon pellets, not around it. Lastly a more fine carbon will be used in the final design, so that it can be packed in tighter and filter out more particulates.
These refined ideas were incorporated in the final design, which will be manufactured durring week 9. Week 8 was also used to cut out a piece of plexiglass that will be used to separate the filter from the container. At first a razor blade was used for the cutting, but it was not effective enough and the glass would crack. Instead, a small circular saw was used, which was far more effective.
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