Project Proposal And Feasibility Study. Team 6. Lucas DeJonge Neal Kruis Dan Nieuwenhuis Chris Zandstra

Transcription

1 Project Proposal And Feasibility Study Team 6 Lucas DeJonge Neal Kruis Dan Nieuwenhuis Chris Zandstra December 7, 2006

2 Table of Contents 1. Abstract Introduction Project Introduction Team Introduction Background Design Approach Design Norms Cultural Appropriateness Transparency Stewardship Caring Design Alternatives Water Filtration Slow Sand Filtration Small Particulate Cloth Filtration Large Particulate Wire Mesh Filtration Water Disinfection Reverse Osmosis Distillation Pasteurization Chemical Additives Ultra Violet Power Solar Biomass Electricity Gravity Design Conclusion Filtration Disinfection Power Prototype Design Slow Sand Filter UV Collectors Feasibility Study Water Quantity Required Energy Water Quality Cost Analysis Conclusion Feasibility Conclusions Further Design Considerations

3 Table of Figures Figure 1 - Typical Slow Sand Filter Design Figure 2 - Absorption Coefficient of Water with Respect to Wavelength Figure 3 - System Flow Diagram Figure 4 - Compound Parabolic Reflector Profile Figure 5 - First and Second Generation UV Array Figure 6 - Third Generation Slow Sand Filter Design Figure 7 - Third Generation UV Array Figure 8 - Current Design Figure 9 - Current Design Figure 10 - Project Task Specifications and Timeline

4 Table of Appendices Appendix A - EES Calculations Appendix B Design Progression Appendix C Cost and Bill of Materials Appendix D Preliminary Time Schedule Appendix E Research and Reference Bibliography Nomenclature CPC...Compound Parabolic Collector MCF...Mully s Children s Family RO...Reverse Osmosis UV... Ultra Violet WHO...World Health Organization 4

5 1. Abstract This paper describes the design considerations of a prototype water purification and disinfection system for use in an orphanage in Kenya. The final prototype design employs a slow sand filter and an ultraviolet (UV) disinfection system working in series. The result is a system that purifies roughly 122 L/day. The slow sand filter performs the double tasks of (a) particulate filtration and (b) biological disinfection. For the prototype, a 3 m (10 ft) tall, 25.4 cm (10 in) diameter PVC tube will be used as a small-scale model of the final slow sand filter. After passing through the slow sand filter, the water is stored temporarily until it is pulled by gravity through the UV system. The UV disinfection system consists of aluminum reflectors which redirect UV light on the water passing through Pyrex tubes. There are 16 reflectors lined up side by side each measuring 8 cm wide and approximately 1.2 m (4.0 ft) long. The result is a UV system which lowers the concentration of common bacteria by a factor of A combination of research and analysis shows that it will be feasible to make the prototype in the spring semester of 2007 within the $500 budget. 5

6 2. Introduction 2.1 Project Introduction The purpose of this project is to design a water purification system which creates roughly 7,000 L of clean water each day. This report discusses the feasibility of the prototype design chosen to model the final system. This is assessed from four perspectives: water quality, water quantity, required energy, and cost. The largest obstacle to overcome is the water quality. Since the engineers involved in the project are trained from a mechanical perspective, water treatment is a foreign topic. As a result, research in the areas of hydraulics and environmental engineering was required. Major methods of water filtration and disinfection have been researched and weighted with design norms to find the most culturally appropriate design. In addition to designing a large scale model that creates 7,000 L/day, a small scale model which produces 122 L/day will be built. This prototype will be a proof of concept which will aid in the design of the final system to be implemented in Kenya. The prototype design is limited mainly from a cost perspective, as a budget of $500 has been designated. 6

7 2.2 Team Introduction From left to right: Neal Kruis, Lucas DeJonge, Chris Zandstra, Dan Nieuwenhuis The team members for this project are four senior mechanical engineers at Calvin College who are completing this report as a requirement of ENGR 339, a senior capstone course. This team was formed because each of the members had a desire to improve the lives of those who do not have the same resources available to them. God has blessed everyone with unique gifts and talents which they are called to use in service to God. The members of Pristine Potables has many different gifts and talents including analytical skills as well as fabrication skills which will mesh well in designing an engineered system which will meet the goal of bringing clean water to those who need it. 7

8 3. Background From the beginning of the project, the team members of Pristine Potables felt that they wanted to make an impact on the quality of life in an underdeveloped area. Several of the members regularly attend Ada Bible Church where numerous global mission operations are based. Through Ada Bible Church the members became aware of a situation in Kenya where there was a need for clean water. Charles Mully operates a collection of orphanages throughout Kenya called Mully Children s Family (MCF). Ada Bible Church works with Mr. Mully to help provide for the growing number of children at his orphanages where a recent drought has created an increasing need for clean water. When Pristine Potables met with Mr. Mully, he specified that that contaminated water is available to use in the designed system. The team is very excited to work with Mr. Mully throughout the course of the project to ensure that all needs and design requirements are met. Team 6 with Charles Mully at Ada Bible Church 8

9 4. Design Approach 4.1 Design Norms Cultural Appropriateness Cultural Appropriateness is the most important design norm for this project. As the location is an underdeveloped area, the materials, resources, and skills used to construct and maintain the system must be locally available. The first phase of the design incorporates a slow sand filter for the filtration of the water. A slow sand filter uses sand as its filtering medium, concrete as its filter container, and various materials can be used for the piping system. All of these materials are readily available in Kenya. A slow sand filter is very simple to construct and maintain. The second phase of the design incorporates a UV collector to disinfect the water. The UV collector uses aluminum to reflect the sun s UV rays taking advantage of the ample sunlight in Kenya. Water flows through the UV collector in a series of clear glass tubes. All of the material required for these collectors is available in Kenya Transparency The large scale model for this project will be constructed in Kenya by members of MCF. As a result, the final design of the system must be easy to understand and fairly simple to construct. Graduates of MCF are trained in trade skills such as construction and welding, so the skills available are wide ranged. One way in which Pristine Potables will ensure transparency is through detailed documentation and extensive work instructions. English is one of the official languages in Kenya; therefore each child will be educated and fluent in English. Also, in talking with Charles Mully, it has been conveyed that the children would be ambitions and eager to work on this project. They are very talented scholars who have a great knowledge base and enthusiasm for learning Stewardship As with any project, there are many ways to complete the task. Pristine Potables decided early in the experiment that alternative and sustainable energy would play a large part in either powering or disinfecting within the system. With the selection of a slow sand filter, it utilizes natural resources and does not require any additives to operate. Kenya is located on the equator; therefore it was important that this system utilized the sun in its operation. The UV collectors that are used for disinfection employ this vast resource. At the orphanages, water is currently pumped into a tower to create adequate pressure; the design of the purification system will make use of the potential energy by making the entire system gravity fed, eliminating the unnecessary use of additional energy. The system will be set-up with the slow sand filter at the highest point allowing the water to travel through the system thus eliminating the need for electric pumps. 9

10 4.1.4 Caring In recent years a drought has severely affected the area where Pristine Potables hopes to implement their project. Pristine Potables hopes to be a part of the solution to this problem and provide for the basic needs of the people at MCF. Currently, the water quality at MCF is very poor. They have no filtration system at all; the only purification that they perform is through boiling the water for cooking. This limited cleaning of the water does not prevent many diseases that infect people in the community. Through this project, clean and healthy water will be made available to the children and will improve the quality of life at MCF. 4.2 Design Alternatives Water Filtration Slow Sand Filtration Slow sand filtration is an effective method of removing particulate and pathogens from larger quantities of water. The largest downfall of such a system is that while it can filter out larger impurities, some of the smaller viruses can still survive the process. For the purpose of this project, this option may well be the most appropriate considering the quantity of clean water required Small Particulate Cloth Filtration While this option may effectively remove even the smallest of pathogens, the largest concern with a small mesh cloth filter is the amount of head loss which results. Another issue with the small particulate cloth filter is that it would have to be maintained on a very regular basis and could be easily damaged by larger particulate. This option was not considered in the prototype design because a slow sand filter is far more effective and requires less maintenance Large Particulate Wire Mesh Filtration This form of filtration may be a necessary pre-process to remove large debris from the system. The quality of the water being pumped from the river to the holding tower which will be the supply for the slow sand filter will determine whether or not a filter of this nature is employed Water Disinfection Reverse Osmosis Reverse osmosis (RO) is an extremely effective method of producing clean water, however a large amount of water is wasted and very high pressures are needed. Another downfall of this type of system is the membrane used for filtration. This membrane is usually made of Gore-Tex which is an expensive material and if the membrane in an RO system is damaged the system is no longer effective and replacement of the membrane is difficult. The previously mentioned issues are the reasons why a RO system was not considered to be viable. 10

11 Distillation Distillation produces very clean and pure water; however, the process is very energy intensive and would require fuels that are either limited or unavailable in the area of application. Due to the alternative energy aspect of this project, obtaining the energy needs required to boil and recondense large amounts of water is very difficult. This process was the first method considered for the project; however, once the energy requirements were determined it was no longer feasible Pasteurization Raising the temperature of water above ~60 C begins the process of pasteurization. Pasteurization is a function of temperature and time. The higher the temperature, the lower the amount of time needed to disinfect the water. One of the downsides to this method is that it does not remove chemical contamination or salts and minerals. Though the water would be safe to drink, it may not be aesthetically pleasing Chemical Additives The use of chemical additives is probably the most common practice in more developed areas, but the processing required and low availability of the resources to implement this practice in more rural areas makes its application too limited. This option has been considered for minimal usage in the storage of the water produced by the system to inhibit any contamination; however the availability of substances such as chlorine is still being researched Ultra Violet Ultraviolet (UV) radiation in the 200 to 400 nm range of wavelength is effective in killing pathogens and other contaminants in the water. UV disinfection is used in many large cities for municipal water treatment. In these systems, water is exposed to large UV lamps for a specified resonance time achieving excellent water quality. In a system designed for a developing region, the sun can be used as a significant source of UV radiation, but daily and seasonal solar behavior makes such a system more difficult to design. Using solar UV requires the construction of a large array of Compound Parabolic Collectors (CPC s) shaped specifically to concentrate light on the flowing water. In this application, turbulent flow or forced mixing of the water is desired for maximum UV exposure, but lower volumetric flow rates and the precise design of the CPC s makes this difficult to achieve Another option would be to use smaller scale UV lamp systems. There are companies who produce systems that would disinfect the amount of water required for this project. Some concerns with the use of UV lamps are the cultural appropriateness of such systems, the availability of replacement parts, and the high cost of such a system. 11

12 4.2.3 Power Solar Ideally the filtration and disinfection processes would be powered by renewable energy. Solar radiation can be used to either distill the water or to simply heat it to an adequate temperature to kill pathogens. Recent research indicates that heating the water with solar energy might require collectors on a scale larger than what is reasonable for the scope of this project. It has been determined that using UV radiation will contribute to a feasible system. An average dosage of 1600 J of UV radiation for every liter of water is needed to decrease the concentration of pathogens by one log 10 scale (i.e. 1 ppm to 0.1 ppm). This dosage requirement can easily be obtained in the design location Biomass Using wood or manure to power a distillation/heating processes might also be an appropriate option. Both fuels are renewable and locally available; however, there is the concern about the emissions that would result from the combustion of the fuels. From further research and discussion, it was determined that biomass is a very complex system which is difficult to use and maintain, and would challenge the transparency of the design Electricity Using an electric pump will provide a way to move the water through the system. This option may be utilized if the design does not function well with gravity alone Gravity The water needs to continually move through the system. Gravity eliminates the need for pumps which could break down and require maintenance. With the system designed to use gravity it simplifies the system and eliminates maintenance and breakdown issues. Using gravity incorporates stewardship and transparency design norms in the project. 4.3 Design Conclusion Filtration The best option for the filtration part of the system is a slow sand filter. The slow sand filter is a simple system which requires minimal upkeep and monitoring. In deciding the filtration method it was necessary to keep the customer (MCF) in mind and make sure that the system would accommodate them in their need for clean water. The slow sand filter consists of layers of varying sand and gravel. The layout of the system is shown in Figure 1. 12

13 Figure 1 - Typical Slow Sand Filter Design Disinfection It is necessary for the system to first have a filtration stage followed by a disinfection stage. A filtration system provides mostly clean water; however, a disinfection stage is necessary to deactivate any remaining pathogens and to prevent re-growth. Solar UV (as opposed to UV lamps) is convenient because it is an inexpensive and renewable method of disinfection. Kenya lies directly on the equator so there will be minimal seasonal variation in the effectiveness of a CPC system at the project site. Although East Africa has a rainy season, it usually consists of only a few hours of cloudy skies in the evening which reduces the effectiveness of the UV disinfection. This will require regular monitoring of output water to control the quality of the water. Total output of the system may change slightly, however the water quality and quantity should still be adequate for potable use. The other option for UV disinfection is the use of UV lamps, which are relatively small loads on an electrical system. The performance of UV lamps makes them a more consistent alternative to solar UV, though the cultural appropriateness of this option may be a concern. It is unclear how available UV lamps are in the Nairobi area and how much they would cost. For these reasons, the prototype design will use solar UV for disinfection; however, future research may reveal that UV lamps are a more appropriate for the final design recommendation. Figure 2 illustrates how a very small proportion of the UV light (wavelengths from 200 to 400 nm) is absorbed by the water allowing the necessary amount of UV light to pass through to deactivate and kill waterborne pathogens. Since the tubes in the UV array will be 2 cm in diameter, only a negligible amount of UV light will be absorbed by the water. 13

14 Figure 2 - Absorption Coefficient of Water with Respect to Wavelength Power Gravity is the best option to power this system because it is reliable and simple. For this reason a gravity fed system saves money and uses less energy making it the most appropriate choice in accordance with the design norms. There is a pump on the site in Kenya which draws water into a water tower. Water will flow directly from the water tower into the slow sand filter system. The flow rate of the inlet water from the water tower will be controlled with a device similar to those found in a toilet bowl. When the float falls to a certain level a mechanically actuated valve will open allowing water to enter the top of the slow sand filter until it reaches the desired height. Water exiting the slow sand filter will deposit directly from the weir into intermediate storage elevated high enough above the ground to push water through the UV disinfection component of the system. A simple ball valve will be placed before or after the UV system to regulate the resonance time. 14

15 5. Prototype Design Figure 3 - System Flow Diagram The prototype shown in Figure 3 is designed around 6 major statepoints. The water inlet at statepoint 1 comes from a water tower which allows water in this system to flow with no power inputs. This system also disinfects the water using only solar UV radiation. The intermediate storage tank (between statepoints 3 and 4) is placed 1 m off the ground so that after the system has been primed, the height difference between points 4 and 6 will drive the system to flow due to gravity. 5.1 Slow Sand Filter The slow sand filter will consist of one 24.5 cm (10 in) diameter, 3 m (10 ft) tall PVC pipe which is filled with different layers of medium. The highest layer will consist of unfiltered water and will be approximately 1.3 m (4.27 ft) tall. The next layer is a thin layer of organic matter on top of the sand, called the schmutzdecke, which is formed after the filter has matured for approximately two months. This layer is the workhorse of the slow sand filter from a biological filtration standpoint. The third layer is 1.3 m of sand which is uniform in grain size and cleaner than normal beach sand. This level of sand cleanliness will be obtained by fabricating a sand 15

16 cleanser which will consist of a large drum or container with perforated pipes in the base which will force water up through the sand placed in the drum. This flow of water will push the biological matter up and over flow out of the drum while the clean sand settles on the bottom of the drum. Four smaller sub-layers of gravel lie below the sand, with gravel diameter increasing with depth. An outlet at the bottom of the 25.4 cm (10 in) PVC pipe leads into the weir. On most slow sand filters the weir is designed to regulate the water level in the slow sand filter above the sand, thus keeping the system from running dry. This aspect of the system was designed to flow directly into the intermediate tank where the water is held prior to moving through the UV collectors. 5.2 UV Collectors The UV section of the system draws water from the intermediate storage tank. This storage tank will be elevated approximately 1 m off the ground to induce flow through the system by the force of gravity. The UV array is mounted on a pivotal stand which can be adjusted throughout the day to capture as much solar radiation as possible. To account for varying height, flexible tubing will be used from the slow sand filter storage tank to the UV array and from the UV array to the end user storage tank. The UV system consists of approximately sixteen tubes and reflectors 1.2 m (4 ft) long that run in series, but stack side to side. The tubes in the UV array will be made of Pyrex for maximum transmittance across UV wavelengths. They will have a 2 cm inner diameter and will be placed at the focal point of the reflectors. The reflectors in the UV array will be designed to maximize the amount of energy put through the tube, and will be constructed from aluminum for optimum UV reflectance. The reflectors will be 8 cm from peak to peak and consist of two parabolic type shapes that meet at the center. Figure 4 shows a side profile of one of the reflectors that will be used. Figure 4 - Compound Parabolic Reflector Profile 16

17 6. Feasibility Study All calculations for the feasibility study can be found in Appendix A. Below are the results of research and calculations for individual portions of the system. Various generations of design are illustrated in Appendix B. 6.1 Water Quantity By design, slow sand filters need to run continuously. In this case it is designed to produce 5.07 L/hr which correlates to 122 L/day. This daily volumetric flow is the constraint that the entire system is designed around. The UV collectors only run during daylight, which was determined to be 8 hr/day. As a result the UV collector is built to move a flow rate that is three times as large as the slow sand filter flow rate, which is 15.2 L/hr. 6.2 Required Energy The entire system is gravity fed. This is possible because the water which is input into the slow sand filter is stored in an elevated water tower. The change in elevations throughout the system creates pressure differences which allow this design to work. The use of Bernoulli s energy equation verifies that the UV disinfection system can be completely gravity fed. The frictional losses from the pipe wall as well as bends and turns in the tubes were calculated. Since the final storage height of the water was known (0.85 m) the initial height in order for pump work to be zero (in other words, the height of water which would negate the requirement of a pump) was calculated to be approximately 1 m. In the UV disinfection part of the process, UV energy will be collected using the array of CPC s. The calculations for this section of the process assume that the concentration of bacteria in the water needs to be reduced by a factor of five log scales, or To do this 1600 J of UV energy per liter is needed for each log scale reduction, resulting in a total of energy requirement of 8000 J/L. From research, the UV intensity for the design location was determined to average 30 W/m 2. Using the volumetric flow rate of the system as well as the absorptance, reflectance, and transmittance of the materials being used, it was determined that the required planar area of the UV array was 1.2 m x 1.2 m. The UV array will collect 622 kj of UV energy used to disinfect the water during each 8 hr period of sunlight. 6.3 Water Quality The overall water quality goal is to conform to World Health Organization (WHO) guidelines for potable water. Slow sand filters use sand and gravel to filter out particulate matter while a naturally forming biological layer commonly called the schmutzdecke removes harmful bacteria. The bottom layer of the slow sand filter consists of four different grain sizes of gravel which increase with depth. The sand (gain sizes of 0.15 to 0.35 mm) lays on top of the gravel layers. 17

18 This process is effective in removing a large percentage of coliforms, cryptospridum, and Giardia cysts. The UV system is designed such that it could act as a stand alone disinfection system. In other words, if the slow sand filter did nothing except remove particulate from the water, the UV system would lower the concentration of certain pathogens by a factor of In reality the slow sand filter uses the schmutzdecke to remove a certain percentage of the bacteria in addition to removing particulate. The UV radiation between the wavelengths of 200 to 400 nm can inactivate protozoa, bacteria, bacteriophage, yeast, viruses, fungi, and algae. The team is still waiting on a water sample results from a government lab in Nairobi. Once the sample is tested and the concentrations of different pathogens are known, the system can then be altered according to specific WHO guidelines. 6.4 Cost Analysis The budget given for this project is $500. This budget is a large restriction on the scale of the prototype. The UV system is the largest cost for this project. The cost for the aluminum sheeting which is used to create the CPC is priced at $110 for a 4 ft x 4 ft x 1/16 in sheet. It is necessary for the CPC to be aluminum because of its ability to reflect UV radiation; therefore, this cost is necessary and could not be reduced. The Pyrex tubes that are used in the UV system make a large contribution to the overall cost. The cost of the tubing in the initial design was $520. Tubes of a smaller diameter were used which resulted in a final design of sixteen 2 cm tubes at a cost of $60. For the slow sand filter, the largest cost constraint was the container used to hold the sand and gravel. After several design changes in the size and material used for construction of the slow sand filter, one 10 in PVC pipe was used which eliminated ineffective piping and space. A preliminary budget was estimated at $1,624, and the final budget is set at $384 (see Appendix C). The changes to the design reduced the budget by more than four times the original amount. The final design is expected to output water at a rate of 7,000 L/day and the prototype will output water at a rate of 122 L/day. The cost scale and the volumetric output scale are not linearly related, therefore the full scale model will not cost sixty times more than the prototype budget ($22,000). 18

19 7. Conclusion 7.1 Feasibility Conclusions The water quantity portion of the project is feasible. The flow rate of the system is mainly determined by the size of the slow sand filter. Through research the system flow rate was determined to be 0.1 m/hr for each square meter of the slow sand filter. A 25.4 cm (10 in) diameter tube would then produce 122 L/day. The UV system is designed around this approximation. The energy required for the large scale design was found to be sufficient. The calculations for the UV system included gravity and solar radiation energy inputs. The system is designed to overcome frictional losses with the use of gravity only. The solar intensity that was approximated for UV disinfection was confirmed by research on the weather conditions in Kenya. Water quality is the most important aspect of the design. Research on existing slow sand filters and UV disinfection arrays have shown them to be very effective separately. However, combining the two will provide a higher level of purity. This is a necessary step to improve quality control. Slow sand filters in many cases are assumed to be sufficient for water purification, but in order to ensure that the water quality conforms to WHO standards, the UV system was added in series with the slow sand filter. From a cost perspective this project has been reworked several times to come within the budget. Initial designs put this project well outside of budget, and through multiple generations of redesign the cost has dropped considerably with an increase in system performance. The final budget includes 40% contingency for unknown variations in fabrication of the prototype. 7.2 Further Design Considerations Major design considerations that have yet to be addressed are (a) the exact equations for the parabolic shape of the reflectors (b) the possible implementation of UV lamps in the final design, and (c) testing on the incoming water quality for the Kenyan project. While a general shape is known for the parabolic reflectors, an exact mathematical model has not yet been determined. The feasibility of using UV lamps in Kenya is an issue which must be addressed, but some research has been done in this area with promising results. Soil and water samples should be obtained in the near future to fine tune the design of the system. These should allow replication of the incoming water at the site in Kenya to test the effectiveness of the prototype. 19

20 Appendix A - EES Calculations 20

21 21

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24 Appendix B Design Progression Generation 1 The first generation of design included the use of a square transparent polycarbonate column which would allow the viewing of the various layers within the slow sand filter. The cost of this column combined with the cost of the UV system was far too great to be feasible given the budget. The UV component of the system can be seen in Figure 5. Generation 2 Figure 5 - First and Second Generation UV Array The second generation of design included using 3 55 gallon drums for the slow sand filter and the UV array was carried over from the first generation which can be seen in Figure 5. This design was far larger than was needed for proof of concept. 24

25 Generation 3 The third generation of design included one transparent pipe along with 3 others for the slow sand filter for the purpose of giving a visual understanding of the inner workings of the slow sand filter as can be seen in Figure 6. The UV system was also modified due to EES calculations which had been performed. This can be seen in Figure 7. Figure 6 - Third Generation Slow Sand Filter Design 25

26 Figure 7 - Third Generation UV Array 26

27 Generation 4 Current Design Choice The fourth generation of design includes the same UV array as in generation 3 but has a new design for the slow sand filter. The slow sand filter consists of one 10 in. pipe which will be opaque but another clear pipe will be used to illustrate the contents of the slow sand filter. This can be seen in Figures 8 and 9. Figure 8 - Current Design 27

28 Figure 9 - Current Design 28

29 Appendix C Cost and Bill of Materials Slow Sand Filter Structure Price Per Qty Price Description $ $ " x 10' PVC Pipe (free from Physical Plant) $ $1.59 1" PVC 90 degree elbow (Lowes) $ $2.55 1" x 10' PVC Pipe (Lowes) $ $ oz. Pipe Primer $ $ oz.pipe Cleaner $ $ oz All Purpose Cement (Adhesive) $ $ gal Storage Tank $ $0.00 Wood stand for storage tank (free from wood shop) $ $25.00 Sand $ $ cu ft Gravel (Old Castle Pebble Rock) $19.95 Contingiency (40%) UV Disinfection System $69.82 Total Price Per Qty Price Description $ $5.00 Ball Valve $ $4.00 Fittings $ $4.00 Fauset $ $ " 15ft. Flexible tube $ $1.55 3/4" x 10' PVC Pipe $ $ cm x 4ft Pyrex UV tubes (1.5mm thickness) $ $ ' x 4' x 1/16" Aluminum Sheet $ $0.00 UV Collector structure (free from metal shop) $ $ gal Storage Tank $89.67 Contingiency (40%) $ Total Total System $

30 Appendix D Preliminary Time Schedule The preliminary time schedule setup by Pristine Potables was initially set up at the beginning of the fall semester in At this time Pristine Potables laid out a timeline for the first semester of work, consisting primarily of research and calculations for the project. Now that the initial design is concluded, Pristine Potables has added a rough time schedule for second semester. Figure 10 on the following page shows the project timeframe and major task specifications 30

31 Figure 10 - Project Task Specifications and Timeline 31

32 Appendix E Research and Reference Bibliography Research "Solar disinfection of contaminated water: a comparison of three small-scale reactors." Science Direct (2003). Engineering Index. Hekman Library, Calvin College. 6 Nov "An Introduction to Slow Sand Filtration." (2005). 10 Nov < Vidal, A, and A.I Diaz. "High-Performance, Low-Cost Solar Collectors for Disinfection of Contaminated Water." (2000). Engineering Index. Hekman Library, Calvin College. 4 Nov Standfield, G, M Lechevallier, and M Snozzi. "W.H.O. Water Treatment Efficiency." (2004). Engineering Index. Hekman Library, Calvin College. 4 Nov "Guidelines for Drinking-water Quality - First Addendum to Thrid Edition." 1 (2006). 4 Nov < Calvin College Faculty and Staff Professor N. Nielsen Professor of Engineering Professor D. Wunder Assistant Professor of Engineering Professor M. Heun Associate Professor of Engineering Dave Ryskamp Metal and Wood Shop Supervisor Marc Huizinga Assistant Mechanical Director Physical Plant 32