Grantee Research Project Results
Final Report: Ultra-Low-Cost Reusable Solar Disinfection Sensor
EPA Grant Number: SU839294Title: Ultra-Low-Cost Reusable Solar Disinfection Sensor
Investigators: Lacks, Daniel J , Mesiano, Sam , Datta, Sanjit , Sinha, Annika , Pfau, David , Saloman, Eric , Yuan, Mona , Chin, Brian , Wagner, Scott , Tippareddy, Charit , MacDougall, Gordon , Sunshine, Kerrin , Cooley, Michaela , Lundgren, Kathryn , Merchant-Wells, Nicholas
Institution: Case Western Reserve University
EPA Project Officer: Page, Angela
Phase: I
Project Period: January 1, 2018 through December 31, 2019
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2017) RFA Text | Recipients Lists
Research Category: Sustainable and Healthy Communities , P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources
Objective:
The goal of this project is to prevent waterborne illnesses by improving solar disinfection, the most cost-effective household drinking water disinfection technique in the developing world. During a solar disinfection treatment, the user places a clear plastic bottle filled with source water in sunlight; there is typically sufficient ultraviolet radiation in six hours of direct sunlight to kill bacteria and other pathogens in the water. While the process is extremely simple, a wide range of factors from cloud cover to water turbidity drastically affect the treatment time. These factors can reduce the reliability of solar disinfection, eroding end user confidence in the technique and thereby preventing practical use of a method that is otherwise extremely accessible, affordable, and effective.
We propose the development of an ultra-low-cost, reusable sensor called OSPRI (Optimized Solar Purification with a Reusable Indicator) that changes color to notify the user that the water is safe to drink. The submersible sensor incorporates a UV-sensitive dye-based indicator formulation that changes color reversibly so that the sensor can be reused daily. Such a sensor would add very little to the long-term cost of solar disinfection but would drastically simplify the technique, thereby making it usable for far more people. The sensor’s design enables it to offer the highest accuracy at low cost while minimizing end-user training. We aim to develop a sensor with cost below $1 and reusability for at least one year.
Summary/Accomplishments (Outputs/Outcomes):
Approximately six months of the twelve-month Phase I project term have elapsed. In that time, we have developed an indicator formulation that slowly changes color in response to ultraviolet exposure and is reusable for at least 30 cycles. We have demonstrated our ability to control the ultraviolet exposure necessary for the color change to occur by altering the composition of chemicals in the indicator formulation. We have also demonstrated that the color change is reversible under the proper conditions, which allows the device to be water-activated and reusable. Finally, we have packaged the indicator formulations into functional prototype devices, which we exhibited at the EPA P3 conference in April 2018.
There have been two particularly notable achievements in the last six months: (1) the development of first-generation functional prototype devices and (2) the development of extensive quantitative methods that will enable us to fulfill our specific research aims. The first achievement required modification of the indicator formulation, which was previously not sufficiently stable to be packaged into a sensor product. We used new processing techniques to stabilize the formulation and incorporate it within a polymer matrix. We then developed a casting technique to apply the formulation to a flexible substrate, which allowed us to build our first functional prototype device. This first-generation prototype, demonstrated at the P3 conference in April, visibly changes color from blue to white after sufficient UV exposure in a solar disinfection bottle and reverses color once removed from the bottle. A second device with a modified chemical composition requires greater UV exposure to change color. These devices continue to be reusable to date, nearly two months after manufacture.
The second key achievement was the development of a wide range of quantitative methods that are crucial to achieving our Phase I specific aims. These methods include automated analysis of spectrophotometric data to calculate parameters reflecting the transition time, reversion time, and cycle-to-cycle degradation of the formulations. We also developed a method to simulate underwater submersion of the formulation and perform a direct comparison of color change kinetics under this condition. We successfully measured the kinetics of bacterial inactivation during simulated solar disinfection treatments (using both a solar UV simulator and sunlight) by measuring residual viable bacteria over time using standard methods
Conclusions:
Functional prototypes of a reusable, dye-based solar disinfection sensor have been designed and built. The components of the design have each satisfied their major technical requirements. The methodologies required to fine-tune these components to the desired specifications have been developed and demonstrated. Therefore, there is a high probability that the Phase I specific aims will be achieved within the project period and that the proposed Phase II approach will yield a fully functional sensor device with the anticipated capabilities.
Supplemental Keywords:
Ultraviolet dosimeter, WASH, diarrheal disease, sustainable water management, drinking water treatment, water purification, water filtration, solar water treatmentRelevant Websites:
Progress and Final Reports:
Original AbstractP3 Phase II:
Ultra-Low-Cost Reusable Solar Disinfection Sensor | 2019 Progress Report | 2020 Progress Report | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.