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An investigation into cistern for rainwater storage and sterilization for the new UBC Student Union Building Salahuddin, Mohammad 2012

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UBC Social Ecological Economic Development Studies (SEEDS) Student Report An Investigation into Cistern for Rainwater Storage and Sterilization for the new UBC Student Union Building Mohammad Salahuddin Murrali Raj Jeyagapal Murtadha Al-Tameemi Vinod Mogan University of British Columbia APSC 262 April 4, 2011 Disclaimer: “UBC SEEDS provides students with the opportunity to share the findings of their studies, as well as their opinions, conclusions and recommendations with the UBC community. The reader should bear in mind that this is a student project/report and is not an official document of UBC. Furthermore readers should bear in mind that these reports may not reflect the current status of activities at UBC. We urge you to contact the research persons mentioned in a report or the SEEDS Coordinator about the current status of the subject matter of a project/report”. An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011     An Investigation into Cistern for Rainwater Storage and Sterilization for the New Student Union Building   Course: APSC 262  Tutorial Instructor: Florence Luo  Authors: Mohammad Salahuddin  Murrali Raj Jeyagapal  Murtadha Al-Tameemi Vinod Mogan  Date Submitted: April 4 th , 2011 An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 2  ABSTRACT  The design of new Student Union Building at UBC is implementing a rainwater harvesting system which includes several major components like collection, filtration, disinfection, storage and distribution. This report looks into the storage system of the rainwater harvesting system in addition to the disinfection approaches applicable to the tank. Moreover, the design of the system needs to cater to the LEED platinum+ Certificate requirements. Underground cistern is made to store water in a tank which can utilize different materials for construction. Materials like galvanized steel, poured concrete and polyplastic have been studied to make a tank of around 22m 3 . Triple bottom analysis was carried out which reflected that concrete is the cheapest option at $250/m 3 and with the least environmental impacts and social implications. Furthermore, chlorination and UV disinfection were chosen to be investigated for possible application to the proposed cistern. Chlorination proved to have low operating cost of only $38/yr but with high initial cost of $1186. For UV disinfection, the capital cost is $600 whereas operating and maintenance costs are close to $70/year. Despite the higher operating cost, UV disinfection is recommended since it has no environmental impacts when used in a tank and no social affects.             An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 3  TABLE OF CONTENTS ABSTRACT....................................................................................................................................2 LIST OF FIGURES.........................................................................................................................4 GLOSSARY ...................................................................................................................................5 LIST OF ABBREVIATIONS..........................................................................................................6 1.0 INTRODUCTION...............................................................................................................7 2.0 CISTERN MATERIAL.......................................................................................................8  2.1 Galvanised Steel.......................................................................................................9   2.1.1 Galvanised Steel Description.......................................................................9  2.1.2 Triple Bottom Analysis for Galvanized Steel..............................................9  2.2 Polyplastic..............................................................................................................10   2.2.1 Polyplastic Description..............................................................................10   2.2.2 Triple Bottom Analysis for Polyplastic.....................................................10  2.3 Poured Concrete.....................................................................................................11   2.2.1 Concrete Description.................................................................................11   2.2.2 Triple Bottom Analysis for Concrete.........................................................11  2.4 Recommended Material.........................................................................................12 3.0 DISINFECTION................................................................................................................13  3.1 Chlorine Disinfection.............................................................................................13   3.1.1 Chlorination Description............................................................................13   3.1.2 Proposed Chlorination...............................................................................13  3.2 Ultraviolet Radiation..............................................................................................15 3.2.1 UV Disinfection Description.....................................................................15 3.2.2 Proposed UV Disinfection System............................................................15 3.3 Triple Bottom Analysis for Disinfection...............................................................16 3.3.1 Environmental Analysis................................................................................16   3.3.2 Social Analysis..............................................................................................16   3.3.3 Economic Analysis.......................................................................................16  3.4 Recommended Disinfection...................................................................................17 4.0 CONCLUSION..................................................................................................................18 REFERENCES..............................................................................................................................19 An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 4  APPENDIX  Appendix A: Reaction for Free Chlorine Formation.........................................................22  Appendix B: Cost Calculation for Disinfection ................................................................23  Appendix C: Disinfection Mechanisms.............................................................................24                            An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 5  LIST OF FIGURES Figure 1: Chlorine Injection System..............................................................................................14 Figure 2: Pellet Chlorination System.............................................................................................14 Figure 3: Schematic of UV disinfection installation upstream of a clearwell...............................15                           An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 6  LIST OF ABBREVIATIONS Abbreviations Expansions CT Contact Time DBP Disinfection By-Products UV Ultraviolet UVC Ultraviolet radiation subtype C O&M Operation & Maintenance Mpa Mega pascal SUB Student Union Building                      An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 7  1.0 INTRODUCTION  The new UBC SUB is projected to be completed by 2014 with an estimated budget of $110 million. Vancouver has an annual precipitation of 1277mm. As a result, the new SUB will be designed with a rain harvesting system that will utilize the approximate 50,000 square feet of available roof surface area in order to collect about 2055 gallons of water per day. The collected rainwater will be filtered and then stored in tank until distributed to the toilet sinks. This report will focus on the cistern that is used to store the filtered rainwater. Furthermore, the scope of the project includes sterilization of the water which is a crucial requirement for water storage. The report will present the several material options available for building a cistern and also the available methods for sterilization. Triple bottom analysis was conducted on each cistern material and sterilization methods. The final decision on the proposed material and sterilization will be based on this analysis taking into account the need to fulfill the requirement for LEED Platinum+ Certificate which is the greenest building rating in North America.                  An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 8  2.0 CISTERN MATERIAL The cistern is a very important component of the entire rainwater harvesting system. The new SUB is expected to harvest and consume roughly 750,000 gallons per year. This large amount of water consumption requires a cistern volume of about 22m 3 . The choice of material for the cistern is an important matter to be considered when making design choices for the new SUB. Among the materials that we are considering for making the cistern are galvanised steel, poly plastic and poured reinforced concrete. These are the three main materials that we found to be the most appropriate ones to make a cistern. Among the factors that have been considered are the environmental impacts, cost, lifetime, density and inertness. Following are the descriptions of why each factor is essential. One of the most important factors to be considered when comparing these materials is their impact on the environment. The new SUB is trying to achieve the LEED Platinum Plus certificate, which requires the design choices to have minimal negative impacts on the environment.. Another important factor is the price of the materials. As this project is to be done in the most sustainable way, having a moderate cost will be helpful in minimising the budget. Not only the material cost is important, but it is also important to consider the lifetime of the materials, since it indirectly reflects the overall cost. The cost is calculated per cubic meter basis. This is because, the volume of a particular material that will be used to build a cistern will be the same regardless of its type. thus by comparing in terms of volume, we can actually observe how expensive or cheap a material is as compared to the others. Certain materials can be cheap but can be used for a short period. This will result in higher long term cost. Next, when building a cistern, it is important to consider its weight. Lighter cisterns can be easily handled during the installation and dismemberment. Thus the material density needs to be considered as well. The reactivity of each material with water and the surrounding is also considered. Rain water, which is being stored in the cistern, can be acidic. Hence, choosing the right material which is inert and non-reactive with acidic water is important. In addition, the material has be to corrosive-free as the collected water will be used for plantation purpose. As a result, these factors have been considered in depth and discussed below for each material. Finally, the response of each material towards fire was also analysed.   An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 9   2.1 Galvanised Steel    2.1.1 Galvanised Steel Description Galvanised steel describes a type of steel which is coated with layers of zinc to prevent metal corrosion. As a result the stored water will not be contaminated due to corrosion. Apart from that, galvanised steel has a lifetime of five years and is considerably cheap. Its tensile strength is also high with the value of 550MPa (Calvert & Farrar, 2008). However, galvanised steel is a heavy material with a density of 7850kg/m 3 (Calvert et al., 2008), which can cause difficulties during installation and dismemberment. Also, in case of fire galvanised steel has the tendency to unbuckle from uneven heating.   2.1.2 Triple Bottom Analysis for Galvanized Steel Environmentally, the use of steel in construction can be viewed as a beneficial choice. One of the environmental advantages of using steel is that it is highly recyclable, with almost 69% of it recycled every year (Barekat et al., 2010). Another advantage is that steel is very efficient when it comes to maintenance; very little energy is required for maintaining steel structures. On the other hand, the use of steel may leave some negative impacts on the environment. The energy used during the process of manufacturing steel is almost twice as much as that of concrete (Barekat et al., 2010). In addition to that, steel cisterns are very heavy, which would require a lot of energy to operate the heavy machinery used to transport and install the cistern. From an economic perspective, choosing steel may not be the cheapest option. As mentioned above, the initial cost of a steel cistern (including transportation and installation) is significantly higher than other alternatives. On average, it costs about $13,816 per cubic meter of steel , which is seven times more than plastic and 55 times more than concrete (MEPS). In addition to that, the corrosive nature of steel makes its lifetime shorter, which requires the cistern to be replaced more frequently. As far as the social impacts go, steel can be beneficial in that it is locally produced. Local communities that make a living from the mining of iron ore that is used in the manufacturing of steel are greatly benefited when steel is consumed. On the other hand, the use of steel in storing water can become poisonous after some time due to the rusting nature of steel. An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 10   2.2 Polyplastic    2.2.1 Polyplastic Description Polyplastics, such as polyvinyl chloride, are another potential type of material that can be used to make a cistern. Polyplastic is chemically inert and does not corrode. It is also ultraviolet stabilised, which means that it does not suffer from the long-term degradation effects due to ultraviolet light, namely sunlight. Polyplastic is also very resistant to cracking and water tight, thus the chances of water leaking out of the cistern are extremely low. In occasions of damage, it is very easy to be replaced and handled as it is light with a density of 1380kg/m3(Calvert et al., 2008). Moreover, polyplastic is relatively cheap and is very durable with a life time of 15 years (UK Cooperative Extension Service, 2005). However, polyplastic tend to have lower effluent level. Water cannot be stored for a long term in a poly plastic cistern tank as it can be toxic. Apart from that, polyplastics also have low tensile strengths. For instance, the rigid polypropylene (PP) has a tensile strength of 35MPa (Calvert et al., 2008). Most types of polyplastic are made from petrochemical compounds, which melt and release toxins in the case of fire.    2.2.2 Triple Bottom Analysis for Polyplastic From an environmental point of view, polyplastic is highly non-recyclable. In addition to that, polyplastic is not biodegradable, which makes it a very environmentally-unfriendly choice. Economically, plastic is relatively cheap. The initial cost for a plastic tank is low when compared to steel; it costs about $2001 per cubic meter of plastic(ICIS.com), which is seven times lower than that of steel. Moreover, plastic has a lifetime longer than that of concrete as well as a lower maintenance cost (UK Cooperative Extension Services). On the other hand, plastic has s cost that is about eight times higher than that of concrete. One of the most important social dangers of using plastic is that it is highly toxic. If water remains in a plastic cistern for a lengthy period, there is a high chance of that water becoming poisonous.    An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 11   2.3 Poured Concrete    2.3.1 Poured Concrete Description Poured reinforced concrete is yet another type of material which can be used to make the cistern. Concrete cistern is long lasting with a life time of 20 years and cheap (UK Cooperative Extension Service, 2005). It is strong and rigid with a high density of 2400kg/m3 (Calvert et al., 2008). In addition, concrete helps lower water acidity level to an extent and has higher effluent levels than a plastics tank. Another added advantage of this material is that the cistern can be made at the exact size and on-site. However, if the concrete wall is not reinforced well, it can crack and can result in leakage. The concrete is susceptible to leak and corrosion, but these can be prevented by having a lining of PVC in the tank. The tensile strength of poured concrete is 40MPa, which is the lowest compared to the other materials being considered (Calvert et al., 2008). Also, if the water has high level of acidity, this can result in reaction between the concrete and the water. Since concrete is a porous material, water can penetrate into concrete through time and can cause corrosion in relation to steel framework. This, however, can be avoided with the usage of liner. In case of fire, the concrete tank has a tendency of exploding.    2.3.2 Triple Bottom Analysis for Poured Concrete From an environmental perspective, concrete has the advantage of being a re-usable material; different applications and structures can afford the use of recycled concrete while maintaining the same standards (Barekat et al., 2010). Since concrete is produced locally, the environmental and financial cost of transportation is relatively low. Economically, concrete may be one of the cheaper options to consider. The initial cost of concrete is lower than that of steel and plastic. It costs about $250 per cubic meter of concrete, which is 55 times lower than that of steel (Service Magic). However, because concrete is susceptible to leaking and corrosion, the maintenance cost for a concrete cistern may be higher than that of other materials. When considering the social impacts of using a concrete cistern, the reactivity of the water with concrete needs to be taken into account. Acidic water is highly reactive with concrete, and could become poisonous if the acidity level is high enough. However, according to Environment Canada, the rain in Vancouver is very unlikely to be highly acidic, since most of An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 12  the wind is coming from the west and acid rain impact is only critical in south eastern Canada (Environment Canada). As a result, the acidity of the water can be safely assumed to be low at most times. On the other hand, concrete structures provide good air circulation, which reduces the likelihood for bacteria to grow inside the cistern (Barekat et al., 2010).   2.4 Recommended Material As was indicated above, each type of material has a set of advantages and disadvantages in each of the three different aspects that were studied. However, some of the costs may be tolerated, while some benefits may not be completely useful to the specific application being investigated under this report.    The highest priority when making a decision regarding which material to choose is the environmental impact. Because the SUB is being considered for a LEED Platinum certificate, the materials used in the building need to be extremely environmentally-friendly. In addition, the ideal choice of material needs to have a positive impact on society, as well as a reasonably low cost.    The process through which we came to choose the most ideal material is by eliminating the least suitable material first. From the information provided above, we can see that polyplastic can be extremely dangerous for its toxicity. This disadvantage is not something that can be tolerated or over-looked. In addition, plastic is not biodegradable or recyclable, which makes it a very harmful choice for the environment. As a result, we chose to eliminate polyplastic. This leaves concrete and steel for consideration. Although steel is a lot more stronger than concrete, this feature is not necessarily useful for the overall quality of the cistern. Moreover, the energy consumed in manufacturing and transporting a steel cistern can be significantly higher than that of concrete one. A concrete cistern does not need to be manufactured in a plant; it can simply be built on-site. Moreover, the initial cost of a concrete cistern is about 55 times lower than that of a steel one. With the above analysis, we propose that concrete is the most appropriate choice of material to use for the cistern. Concrete is cheap, strong, rigid and inert when used with non- acidic water, which is the case with much of the collected rainwater in Vancouver.   An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 13  3.0 DISINFECTION  The filtered rainwater entering the cistern need to be sterilized as they contain harmful chemicals and microorganisms. There are several commercial methods available to sterilize the water like chlorination, ozonation, UV disinfection, chloro-amine, chlorine dioxide, hydrogen peroxide addition. Based on our research, the two best methods applicable to the new SUB are delved in detail.   3.1 Chlorine Disinfection  Chlorine is used for primary disinfection at water treatment plants to meet contact time (CT) requirements for inactivation of Giardia and viruses (Lehr, Keeley & Lehr, 2005). When using free chlorine for disinfection, it is typical to provide a period of free chlorine contact time with a clearwell following filtration. Free chlorine is also widely used for residual disinfection; however, its residual decays more rapidly than a monochloramine residual in the distribution system and free chlorine also typically forms disinfection by-products (DBPs) more quickly than monochloramine (Reynolds & Richard, 1996).    3.1.1 Chlorination Description  When chlorine is added to water it reacts with microorganisms, certain chemicals, plant material, and compounds that can cause taste, odor or color in the water (Letterman, 1999). These components "tie up" some of the chlorine and this is called the chlorine demand. The chlorine demand exerted by organic and inorganic compounds present in the water must be overcome; chlorine is then present as “free chlorine” (Reynolds et al., 1996). If ammonia is present, the chlorine reacts with ammonia to form chloramines (Reynolds et al., 1996). These reactions are substantially the same, regardless of which form of chlorine is used. The disinfecting ability of chlorine is due to its powerful oxidizing properties, which oxide those enzymes that are essential to the cells’ metabolic process (Excel Water Technologies, 2007).    3.1.2 Proposed Chlorination  For the chlorine application in the cistern chlorine cylinders (125-lb cylinders or l-ton containers), evaporators (in some cases), chlorinators, and injectors need to be installed (Lehr et al., 2005). Furthermore appurtenances, such as scales and injection systems are also required. In An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 14  our system, chlorine can be applied in either dry form as a powder or pellets (calcium hypochlorite), illustrated in figure 1 or in liquid form (sodium hypochlorite) shown in figure 2. (Lehr et al., 2005). Both forms of chlorine must be stored in accordance with the manufacturers' recommendations for safety purposes and to maintain the chemical integrity of the product. In the liquid chlorination system using sodium hypochlorite, a fixed amount of chlorine solution is delivered with each pump discharge stroke whereas for pellet system, chlorine pellets are directly dropped into the well. Due to economic and operational considerations of the cistern, liquid chlorination system is recommended.  Figure 1 : Chlorine Injection System (Excel Water Technologies, 2007)   Figure 2 : Pellet Chlorination System(Excel Water Technologies, 2007)      An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 15   3.2 Ultraviolet Radiation  UV is an effective primary disinfectant against Giardia, Cryptosporidium, bacteria, and many viruses (Hatt, Belinda Deletic & Fletcher, 2005). UV systems typically are located downstream of filtration, but UV disinfection can be applied to unfiltered water supplies, surface water, or groundwater with sufficiently high transmissivity.  3.2.1 UV Disinfection Description  UV disinfection is a physical disinfection method; other methods rely on chemical agents. UV light penetrates the cell wall and causes photochemical damage to the cell’s DNA and RNA. UV light is part of the electromagnetic spectrum. Short-wave UV, or UV-C, spans 200 to 280 nm and is the most “germicidal” band of UV light (Lehr et al., 2005). Damage to DNA and RNA effectively inactivates the cell as they carry genetic information for reproduction (Lehr et al., 2005).  3.2.2 Proposed UV Disinfection System  An overview of the proposed UV disinfection system is shown in figure 3 where UV lamp with effective wavelength of 254nm is used for microbial inactivation (Reynolds et al., 1996). The system requires the continuous application of UV light as water passes through the UV disinfection system. Consequently, it also requires a stable and reliable power source.  Figure 3 : Schematic of UV disinfection installation upstream of a clearwell (Lehr et al., 2005) An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 16  3.3 Triple Bottom Analysis for Disinfection  Chlorination and UV disinfectant are both effective disinfectant for the stored cistern water. A detailed triple bottom analysis was performed to choose the best option to implement.  3.3.1 Environmental Analysis.  In chlorination, chlorine dissolves when mixed with water which can further form disintegrated by products that can be harmful to the environment even at low levels. DBP like organochlorines and dioxins remain in the environment as they do not break down readily and therefore bio-accumulate. On the other hand UV does not generate any unwanted DBPs as UV light is not a chemical agent. Furthermore, it is environmentally friendly, no dangerous chemicals to handle or store and no problems of overdosing . However, there is a slight possibility of mercury contamination into the water due to UV lamp leakage. (Reynolds et al., 1996).    3.3.2 Social Analysis.  UV disinfection system handling may lead operators to exposure to radiation which can lead to skin cancer due to immediate mutation or change in immune system. Chlorination also has several social impacts. Water with chlorine concentrations above five parts per million (ppm) are irritating to the nose, throat, and eyes and even in concentrations around 1-3 ppm causes mild eye and respiratory-tract irritation after several hours. (Choi et al., 2010) Chlorine is also known to have long term residual effects on organisms especially living in water and in soil. However, using chlorination will benefit the local chemical industry as the high water consumption for UBC’s new SUB will reflect into greater demands for sodium hypochlorite, ammonia and other associated chemicals.    3.3.3 Economic Analysis  The initial operating cost for chlorination is quite high at $1186 which includes meters, pump, pressure tanks, etc. The high initial cost for chlorination is due to additional pumping, validation testing and evaluation of complex test. This high cost is offset by the low chemical cost of hypochlorite which will be $38/year only. For UV disinfection, initial capital cost is only An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 17  about $600 whereas the UV dose will cost around $56/year and the bulb replacement cost is $15 each year. Detailed calculations in Appendix B.   3.4 Recommended Disinfection  The use of chlorine gas is a well-established, proven approach that is attractive due to its simplicity and cost-effectiveness in the long run. However, obtaining a LEED Platinum+ Certificate will not favour the use of chemicals in the filtered rainwater. On the other hand UV is a chemical free method that is disfavoured only due to high operating cost. The main objective of the SUB is to go greener and the higher UV operating cost is so minute that we recommend UV disinfection for the Cistern Rainwater filtration system.                   An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 18  4.0 CONCLUSION  This report has looked into three different materials that can be used to build a cistern tank. Their properties and effects have been studied. Furthermore, triple bottom analysis was conducted on each type of material to determine the cost and benefits from environmental, economic and social perspectives. From our study, we were able to exclude polyplastic because of its potential to make stored water toxic as well as its non-recyclable, non-biodegradable nature. Steel was also eliminated because of its high initial cost and the high levels of CO2 emissions during the manufacturing process. In the end, we came to the conclusion that concrete is the most suitable option for this application. Concrete is cheap, strong and has minimal negative environmental impacts.  A secondary topic investigated in this report was disinfection of water in the cistern. Two clear effective methods: chlorination and UV disinfection were delved in detail. Further analysis of each process and the target of chemical free environment resulted in choosing UV disinfection for the cistern. It has barely any environmental impacts when used inside a water tank. Furthermore, UV disinfection does not pose any social impacts as well. Initial operating cost is low enough to offset the operating cost over the years and the operation is simple.              An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 19  REFERENCES Barekat, F, Han, DY, Dewan, M, & Qian, A. (2010). An investigation into the use of wood vs.  steel and concrete in construction of the new sub. Student report, Social Ecological  Economic Development Studies, University of British Columbia, Vancouver, Canada.  Retrieved from http://www.sustain.ubc.ca/sites/default/files/seedslibrary/APSC261_  SustainableAlternativesBuilding_Group01_Clean.pdf  Baruth. E. E. (Ed.). (2004). Water Treatment Plant Design. (4th ed.). New York, NY: McGraw-Hill.  Calvert, J.R & Farrar, R.A. (2008). An Engineering Data Book (3rd ed.). Basingstoke: Palgrave  Macmillan  Choi, K., Sun, M., & Terry, B. ((2010). An Investigation into the Water Management for The Proposed New Student Union Building (Degree Student Report). Retrieved from http://www.sustain.ubc.ca/  ENR Construction Cost Index (1908 – 2001). Retrieved from  http://www.sao.wa.gov/EN/Audits/LocalGovernment/LocalGovernmentResources/Docu  ments/ENR%20Construction%20Cost%20Index%20(1908%20-%202001).pdf  Environment Canada. (2008). Measuring Sustainability: Canadian Environmental Sustainability  Indicators. Retrieved on March 15,2011, from http://www.ec.gc.ca/indicateurs-  indicators/default.asp?lang=En  Excel Water Technologies Inc. (2007). Continuous Chlorination. Retrieved from http://www.excelwater.com/eng/b2c/chlorination.php    An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 20   Gadgil, A., Greene, D., & Drescher, A. (1998). Low cost UV disinfection system for developing  countries: field test in south africa. Proceedings of the First International Symposium on  Safe Drinking Water in Small Systems. Retrieved from:NiG _MzFkt9QJ:eetd.lbl.gov/iep/  archive/uv/pdf/LoV-final results.pdf+typical+UV+disinfection+price&hl=en&g  Hatt, Belinda E., Deletic A., and Fletcher T. D. “Integrated treatment and recycling of stormwater: a review of Australian practice.”Journal of Environmental Management 79. 26 Oct. 2005: 102-113. Department of Civil Engineering, Institute for Sustainable Water Resources, Monash University. Retrieved from <www.elsevier.com/locate/jenvman>  ICIS.com. (2011). Polypropylene (PP) Prices and Pricing Information. Retrieved on March 15,  2011, from http://www.icis.com/V2/chemicals/9076429/polypropylene/pricing.html  Lehr, J., Keeley, J. & Lehr, J. (2005). Water Encyclopedia, Volumes 1-5. In Chlorine and  Chlorine Residuals (pp. 127-130). John Wiley & Sons.  Letterman, R.D. (5th ed.). (1999). Water Quality and Treatment - A Handbook of Community  Water Supplies. In Disinfection (pp. 14.1-14.60). McGraw-Hill.  MEPS. (2011). Steel prices online. Retrieved on March 15, 2011, from http://www.meps.co.uk  /world-price.htm  National Service Center for Environmental Publications (NSCEP). (1986, Oct.). <i> Design  Manual Municipal Wastewater Disinfection</i> (EPA/625/1-86/021 ed.).Cincinnati, OH:  Author. Retrieved from http://nepis.epa.gov/<br>  Reynolds, T. D. & Richards, P. A. (2nd ed.). (1996). Unit Operations and Processes in  Environmental Engineering. In Disinfection (pp. 740-754, 766-768). Stamford,  CT:  Cengage Learning.  An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 21  ServiceMagic. (2011). Concrete cost: A Primer. Retrieved on March 15, 2011, from http://www.  servicemagic .com/article.show.Concrete-Cost-A-Primer.14119.html  The economic advantages of chlorine gas disinfection. (n.d.). Retrieved from  http://www.hydroinstruments.com/page.aspx?page_id=38  UK Cooperative Extension Service. (2005). Choosing Cistern Material and Location. Retrieved  from : www.ca.uky.edu/enri/pubs/enri204.pdf+Choosing+Cistern+Material+and  +Location&hl  Water Storage Extras Oasis Design. Includes Water Tank Calculator. Retrieved from:  http://www.oasisdesign .net/water/storage/extras/                  An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 22  Appendix A Reaction for free chlorine formation:   From Cl2 (gas):  Cl2(g) + H2O ↔ HOCl + H + +Cl -  HOCl ↔ H++OCl-   Hypoclorite of calcium (solid):  Ca(OCl)2 →Ca 2+ + 2OCl -    Hypochlorite of sodium (liquid):  NaOCl → Na+ + OCl-                 An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 23  Appendix B Chlorine Chemical Cost Calculation:  Chlorine = $2/pound Scale down factor = 1mgd/0.002055mgd = 486.6 Chlorine required = 4661 pounds @ 1ppm/scale down factor  Chlorine required = 4661/486.6 = 9.57 pounds @  1ppm Chlorine required  @ 2ppm = 9.57 * 2 = 19.14 pounds Total Chlorine chemical cost for a year = 19.14 * $2 = $38/year  UV disinfection operating cost:  At UV dose of 40,000 µW-s/cm2 = $0.02/m 3  of water Per year need to disinfect 750,000 gallons of water or 2839m 3  Total cost of disinfection dose = 2839 * $0.02 = $56/year Bulb replacement cost every 7500 hours = $15             An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Appendix C  Table 1 : Disinfection mechanisms and effectiveness (Lehr et al., 2005). An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 25   Table 1 : Disinfection mechanisms and effectiveness (Lehr et al., 2005). continued  An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 26   Table 1 : Disinfection mechanisms and effectiveness (Lehr et al., 2005). continued  An Investigation into Cistern for Rainwater Storage and Sterilization April 4, 2011  Page | 27   Table 1 : Disinfection mechanisms and effectiveness (Lehr et al., 2005). continued 

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