The UV-Tube Project is part of the Renewable and Appropriate Energy Laboratory (RAEL) at University of California at Berkeley. The project focuses on improving water quality for people in developing areas where other water treatment methods are not applied consistently because of their cost, inconvenience, complexity, or energy requirements. The goal of the UV-Tube Project is to design and promote the UV-Tubean affordable, simple, and easy to use household water disinfection device that uses ultraviolet (UV-C) light to inactivate pathogens. UV-Tubes can be built from materials available in developing areas and thus can be disseminated easily through community workshops hosted by local non-governmental organizations or sold by small-scale entrepreneurs.
The UV-Tube is a design concept. All UV-Tube designs incorporate a germicidal bulb suspended over water in a horizontal tube or covered trough. The water enters at one end through an inlet in the top of the tube, and then flows along the bottom (beneath the germicidal bulb) until it reaches an outlet at the opposite end where it exits. The height of the outlet sets the depth of the water in the tube and regulates the hydraulic detention time. Because the UV-Tube does not require water pressure to operate, it may be connected directly to a faucet or filled with a funnel and bucket, as shown above.
The approach of the UV-Tube Project is to work iteratively alternating between laboratory validation and field testing and refinement. We are developing a variety of well-tested (i.e. safe and highly effective) designs that can be built from widely available parts to be used by individuals and institutions worldwide. Individual households, local NGOs (non-governmental organizations) or local entrepreneurs will have access to instructions to build a UV-Tube for personal use, distribution or sale. There are currently three UV-Tube designs and other related non-tube designs.
The first UV-Tube was made out of widely available PVC pipe. Currently, three materials (stainless lined PVC, concrete, and pottery) and three bulb sizes (36, 18, and 15) are being considered. Each design is tested for germicidal effectiveness, material stability and appropriateness in the field. First, tests are conducted in the Renewable and Appropriate Energy Laboratory at UC Berkeley to determine how well the prototype inactivates pathogens and how well the materials hold up under the high-energy UV-C light. The prototype is then field tested to determine cost, materials availability, and user preferences. Finally, the design is modified based on user feedback and retested in the laboratory, as necessary. The germicidal effectiveness and materials tests have been completed for the PVC lined with stainless steel and field tests are underway in Mexico. We have also begun preliminary testing on UV-Tube prototypes made from concrete and low-fired pottery and are working on building or obtaining new prototypes constructed of high-fire pottery and ferro cement. Eventually, each design that satisfies the laboratory tests will be evaluated for sustainability through field testing in developing communities. As the project progresses, all the designs and test results will be made available on the internet and in printed handbooks, so that each household, community organization, or entrepreneur can choose the design that is most suited to their location and preferences. They will have access to instructions for building a UV-Tube, a parts list and simple brochures explaining operation and maintenance procedures.
In the early 1990s, Dr. Ashok Gadgil, a Senior Staff Scientist at Lawrence Berkeley National Laboratory, designed a community-scale UV disinfection product called UV Waterworks for use in developing countries. Later in that decade, Dr. Lloyd Connelly, while installing several UV Waterworks devices in the Pátzcuaro region of Mexico, found that there was a need for a less expensive and simpler household treatment method. In response, Dr. Connelly downscaled and simplified the technology, creating the UV-Tube for which he later won the World Bank Development Marketplace competition, which provided funding for further testing and field trials of the technology. Design work and laboratory testing based around the stainless steel lined PVC version of the UV-Tube continued throughout 2000 and 2001.
Then, during summer/fall 2001, a preliminary field study on the stainless lined PVC UV-Tube was conducted in Pátzcuaro, Mexico in collaboration with a local NGO, Grupo Interdisciplinario de Tecnología Rural y Apropiada Interdisciplinary Rural and Appropriate Technology Group (GIRA).
During the Summer of 2002, the UV-Tube Project received a grant from the National Collegiate Inventors and Innovators Alliance (NCIIA) which allowed for preliminary testing of the concrete and pottery UV-Tube designs and provided some funding for the full scale field trial of the stainless steel lined PVC design. A trip to Cuernavaca, Mexico in January 2003 established a partnership between the UC Berkeley UV-Tube Project and Instituto Mexicano de Tecnología del Agua, (IMTA), the Mexican Institute of Water Technology. IMTA has validated the stainless steel lined UV-Tube according to the Mexican standard for point of use water treatment devices and is currenlty conducting a field study.
To determine the germicidal effectiveness of each UV-Tube prototype, MS2 bacteriophage was used to determine the average fluence (dose) of UV light at a specified flow rate. First, a fluence-inactivation curve was generated for the MS2 by exposing samples to varied amounts of UV light using a bench-scale quasi-collimated beam apparatus. Water with a UV254 transmittance of 73% was inoculated with MS2 and then passed through the UV-Tube prototype at three flow rates. The log inactivation of the MS2 was compared with the fluence-inactivation curve to determine the fluence (dose). Results are shown below on a plot of inactivation data for pathogens of concern (compiled from various sources). All designs, at the flow rates tested, provide a fluence which exceeds the 38 mJ/cm2, as required by the National Sanitation Foundation standards (NSF/ANSI 55 Ultraviolet Microbiological Water Treatment Systems).
Vertical lines correspond with the following test results:
620 J/m2: Large Stainless Steel Lined PVC at 8 L/min
630 J/m2: Medium Pottery at 5 L/min
920 J/m2: Large Stainless Steel Lined PVC at 5 L/min
980 J/m2: Large Concrete at 5 L/min
More information on the bioassay procedure and results
Tracer studies help to characterize the flow dynamics of the UV-Tube and reveal potential problems. A standard absorbance curve at 550 nm is developed for Rhodamine dye using a spectrophotometer. Rhodamine dye is then injected into the inlet of the UV-Tube tube design while the water is flowing at a specified flow rate. Samples are taken every 3 seconds and the absorbance is measured on the spectrophotometer. Exit age distribution, E(t) and cumulative age distribution, F(t) curves are determined and the experimental mean residence time, tbar is calculated. Significant short circuiting, wide E(t) curves, or large differences between the theoretical hydraulic residence time, and tbar would suggest that some microorganisms passing through the reactor may not receive sufficient UV fluence (dose) to be inactivated.
UV-Tube materials and designs were filled with water and exposed to UV light. The water was then analyzed to determine if any potentially harmful products were formed. All tests were conducting conservatively, assuming a long residence time. These tests helped to determine that unlined PVC would not be a suitable material. The PVC lined with stainless steel design was tested by collecting water from the inlet and outlet and analyzing it for 72 common volatile organic compounds (VOCs). The results indicated that the UV-Tube should only be turned on for use and water should be drained after use. Flow through samples were non detect for all 72 compounds. However, after a 16 hour exposure the water contained 160 micrograms per liter acetone. While this amount of acetone is well below the EPA oral reference dose, it was still considered better to avoid.
More informationon material degradation testing procedure and results
Manufacturers recommend that UV bulbs warm up for 10 minutes before use and that they remain on continually to ensure provision of their rated UV output for 1 year. However, these conditions are not ideal for UV-Tubes operated where electricity is intermittent, expensive, or provided by solar or battery power. Also, turning the ss-PVC UV-Tube off between uses reduces the risk of PVC by-product formation. Because little information is available from the manufacturer on bulb UV output and lifetime under non-ideal operating conditions, we are conducting bulb studies with the following goals:
|1.||To determine the effect of cycling (switching on and off) on the lifetime of the bulb.|
|2.||To determine the effect of cycling on bulb UV output as a function of time and number of cycles.|
|3.||To observe the fluctuation of bulb output during the warm-up period and how long it takes for the irradiance to stabilize.|
We are interested in the technical, economic, and social viability of each UV-Tube design in the field. We hope to better understand the efficacy and durability of the UV-Tube under real-use conditions, for a prolonged period. UV-Tube durability and frequency of replacement will affect its environmental sustainability (generation of solid waste) and economic feasibility for the users (replacement costs). Also we investigate the appropriateness of the design and how it is-or is not-accepted by the users. Finally, we compare possible dissemination methods to determine if a sense of ownership plays a role in the success of in-home trials of the UV-Tube and assess potential users' ability and willingness to pay for a UV-Tube.
Initial field work returned to the location where the UV-Tube was first developed by Dr. Connelly, in the villages surrounding Lake Pátzcuaro in Mexico. In collaboration with a local NGO, Grupo Interdisciplinario de Tecnologías Rurales y Apropiadas Interdisciplinary Rural and Appropriate Technology Group (GIRA), during the summer/fall of 2001, volunteers at a community workshop in Pátzcuaro each assembled a UV-Tube using a PVC pipe lined with stainless steel.
We provided GIRA with background materials on UV disinfection and the UV-Tube and assisted in purchasing materials and planning a community education and construction workshop. GIRA identified a group of participants who were willing to take part in the workshop, install the UV-Tube they built, and allow us to test the UV-Tubes performance biweekly. The one-day workshop, shown in photograph below, combined discussion of the water/health connection and construction of a UV-Tube. Each volunteer was provided with parts, tools and an illustrated construction manual. Each successfully constructed their own UV-Tube. These UV-Tubes were installed in residences and tested for water quality, durability, and user-friendliness. The users provided suggestions for improving the design. Because this field study was conducted at an intermediary step, before full confirmation of the safety and effectiveness of the design, participants were requested not to drink the water from the UV-Tube.
Haiti Outreach: Pwoje Espwa (H.O.P.E.) promotes grassroots development by providing technical, educational, and financial support in the community-defined priority areas of health, education, and economic development to the areas surrounding Borgne, a rural town on the north coast of Haiti.
Three commercial ultraviolet drinking water disinfection units were installed in Borgne in 2000. One is located at the clinic and two were installed with a local development group and are operated by water committees. The systems provide safe drinking water to neighborhoods in and outside of Borgne for a minimal fee.
Diagnostic data from the H.O.P.E. Health Clinic indicate that at least a quarter of all patients come to the clinic suffering from preventable waterborne illnesses. In response, the latest H.O.P.E. project is the Sant Teknoloji Bwase Lide (The Brainstorming Technology Center), opened in July 2003. The overall goal of the Sant is to inspire local confidence and creativity in environmental problem solving, and the current focus of that creativity is prevention of waterborne illnesses. The center has a staff of four quarter-time local employees who offer traveling seminars and radio programs on waterborne illness prevention and simple water treatment and sanitation techniques such as UV, SODIS, solar cooking, and ecological sanitation. The staff also provides water testing services and opens the Sant Teknoloji twice a week for visitors to try out technologies used around the world. Staff members report that the community is very interested in water treatment technologies including SODIS and UV, ecological sanitation with dry toilets, and composting. Various community groups have submitted proposals to H.O.P.E. and the Sant Teknoloji for community or neighborhood-scale water treatment projects. Unfortunately the water systems currently in use are expensive and susceptible breakdowns. A simple, sustainable water treatment method that can be built using local knowledge and materials-possibly the UV-Tube-is desperately needed to supply the area with safe, affordable drinking water.
The UV-Tube Project is planning to work with members of H.O.P.E. in the United States who will then work with the staff of the Sant Teknoloji in Haiti to empower rural Haitians to refine the ferro-cement UV-Tube for their community's use. They will provide technical support, educational materials, and validation of new ferro-cement UV-Tube designs as requested by the community. Once a design is validated, H.O.P.E. intends to field test the ferro-cement UV-Tube as a community water treatment system.
For further information on H.O.P.E.: http://haitimedical.com/hope/
The Instituto Mexicano de Tecnología del Agua, (IMTA) - The Mexican Institute of Water Technology in Cuernavaca, Mexico performs research to develop, adapt and transfer technology and provide technological services, preparing qualified human resources for the management, conservation, and remediation of water and associated natural resources. IMTA has perfomed laboratory validation of the UV-Tube according to the Mexican standard for point of use drinking water treatment technologies. They have also begun a field trial with UV-Tubes installed in the homes of local volunteers.
In Mexico the waterborne illness situation is less severe than Haiti, however many people still lack access to safe drinking water. UV disinfection is a promising household technology because many households have both electricity and piped water (although it is not necessarily contamination free) in their homes. Over the last few yeas, the Mexican government has been promoting research on and implantation of household-scale drinking water treatment systems. Our partner organizations are the Mexican Institute of Water Technology (Instituto Mexicano de Tecnología del Agua, IMTA) and the National Council for the Promotion of Education (Consejo Nacional de Fomento Educativo, CONAFE). IMTA has done extensive work to promote SODIS (solar disinfection using plastic bottles and sunlight) in rural areas including research to optimize the SODIS procedure and the production of educational brochures and videos for use by NGOs disseminating the technology. In January 2003, the UV-Tube project team presented the first UV-Tube design to IMTA investigators as an inexpensive household treatment option. The investigators were interested in exploring the technology further and validated the UV-Tube according to Norma 180, the Mexican standard for household drinking water treatment units. Graduate students at IMTA then improved the UV-Tube design and are currently field-testing three UV-Tubes near Cuernavaca where public electricity and piped (but microbiologically unsafe) water are available.
For further information on IMTA: http://www.imta.mx/
Consejo Nacional de Fomento Educativo (CONAFE) - National Council for the Promotion of Education, is a Mexican development organization located in Baja California Sur who seeks to address inequities through improved education. While their main function is to provide primary education in small rural communities in Mexico, they also support community based development projects such as rural Photovoltaic (PV) electrification. The UV-Tube Project hopes to partner with CONAFE to promote, via educational programs especially targeted to children, the basic sanitation practices and the importance of clean drinking water. CONAFE instructors will also play a key role in the dialogue between the community members and the Berkeley team.
In Baja California Sur, CONAFE has reported lack of access to potable water in most of the communities where it operates. CONAFE authorities aver that water contaminated with microorganisms is one of the leading causes of instructors' and children's absenteeism in rural schools. The ESW-Berkeley "Agua SALud" project team worked with CONAFE during summer 2004 to test drinking water sources in the communities of Baja California Sur. Their water testing results confirmed that more than half of the population drink water containing fecal contamination. Members of the Agua SALud team have now joined the UV-Tube Project and are planning to field test the UV-Tube in Baja California Sur concurrently with the IMTA field study. Funding for the Baja California Sur field study will be provided by the United Nations Industrial Development Organization (UNIDO).
For further information on CONAFE: http://www.conafe.edu.mx/
The UV-Tube provides an affordable option compared to purchasing bottled water, boiling or using a commercial UV disinfection system. The cost of the UV-Tube is higher than that for chlorine addition, however UV disinfection has many other adventages over chlorine, which requires an inconvenient contact time, is less effective at eliminating protozoa, helminthes, and some viruses and is difficult to dose, as the amount required depends on the water quality. Users also complain that both boiling and chlorine addition lead to a adverse change in the taste of the water.
|Options||Start-Up Cost ($)||Monthly Cost ($)||Average Monthly Cost for First Year|
|Boil Water (using LPG)||$20-30||$10||$11|
|Purchase Bottled Water||$3||$12||$12|
|Commercial UV System||$300||$1||$26|
The development of a local and sustainable dissemination model is an integral and integrated part of our laboratory and field-based project approach. It has been widely acknowledged that successful technology transfer projects rely on user involvement and investment. We recognize that to be effective, the system not only has to be designed well technically and be socially practical and affordable, but also distributed and introduced in such a way to ensure continued use. Our design approach incorporates indigenous local knowledge at every step and our dissemination strategy aims to provide the users with a sense of ownership of the product.
Distribution of the UV-Tube may proceed along one or more of the following paths:
The UV-Tube Projects goal in the longer term is for fabrication and distribution of this technology to become increasingly decentralized and self-sustaining. Beyond our initial laboratory work, manual preparation, and marketing studies, we envision our primary activity as being the maintenance of a web-based information center where ideas, alternate fabrication processes, questions, and contacts can be continually updated. The laboratory at UC Berkeley will also continue to be a testing center for new designs.
UC Berkeley June 2003 Press Release
UV-Tube field work in Haiti in UC Berekely's Engineering News and Rochester Institute of Technology's The University Magazine
The UV-Tube receives the Massachusetts Institute of Technology IDEAS International Technolgy Prize
National Collegiate Inventors and Innovators Alliance E-Team Award UV-Tube display to public at the Museum of Science in Boston
We thank the organizations that provided support during various aspects of this project: Lindbergh, for providing the grant that supported Lloyd Connellys initial research with the UV-Tube; The World Bank Development Marketplace 2000 for supporting the first two years of laboratory work and the field trial; National Collegiate Inventors and Innovators Alliance for support of MS2 validation and the initiation of the second field trial; Solo Energy Corporation and the Energy Foundation for support to the Renewable and Appropriate Energy Laboratory, which houses The UV-Tube Projects laboratory facilities. National Instruments. Environmental Protection Agency. We also thank Florentino Mota, Omar Masera and Jaime Navia from Grupo Interdisciplinario de Tecnología Rural y Apropiada in Pátzcuaro, Mexico and Cesar Calderon Molgora and Arturo Gonzalez Herrera at the Intstituto Mexicano de Tecnologia del Agua (IMTA), Juitapec, Mexico.
Sarah Brownell, Department of Civil and Environmental Engineering, UC Berkeley
Alicia Cohn, Renewable and Appropriate Energy Laboratory, UC Berkeley
Dr. Lloyd Connelly, School of Medicine, UC Davis
Dr. Kara Nelson, Professor in Civil and Environmental Engineering, UC Berkeley
Dr. Daniel Kammen, Professor in the Energy and Resources Group, and Goldman School of Public Policy, UC Berkeley
Laura McLaughlin, Department of Civil and Environmental Engineering, University of Washington
Rachel Peletz, Civil and Environmental Engineering, UC Berkeley
Fermin Reygadas, Energy and Resources Group, UC Berkeley
Amy Janel, Civil and Environmental Engineering, UC Berkeley
Xanat Flores, Civil and Environmental Engineering, Massachusettes Institute of Technology
Margaret Rhee, Haas School of Business, UC Bekeley
Micah Lang, Energy and Resources Group, UC Berkeley
Forest Kaser, Energy and Resources Group, UC Berkeley
Sarah Stafford, Civil and Environmental Engineering, UC Berkeley