Grantee Research Project Results
Final Report: Enhancing Performance and Social Acceptability of the Ventilated Improved Pit Toilet
EPA Grant Number: SU834297Title: Enhancing Performance and Social Acceptability of the Ventilated Improved Pit Toilet
Investigators: Watkins, David , Paterson, Kurtis G. , Michalek, Donna J. , Thode, Ashley , Hanson, Cara , Gossen, Craig , Landick, Kimberly , Guzak, Kristine , Marek, Stefan , Fuchs, Valerie
Institution: Michigan Technological University
EPA Project Officer: Page, Angela
Phase: I
Project Period: August 15, 2009 through August 14, 2010
Project Amount: $9,991
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2009) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Safe and Sustainable Water Resources , P3 Awards , Sustainable and Healthy Communities
Objective:
Approximately two-fifths of people worldwide do not have access to improved sanitation [1], and as many as 5,000 children die every day because they lack sanitation and potable water [2]. Gaining access to sanitation reduces diarrheal deaths by 30% in children, saving up to 1,500 lives daily [3]. Appropriate technologies exist that could increase access to sanitation, but the percentage of people lacking sanitation continues to rise. The design phase for appropriate sanitation involves determining the appropriate toilet for the region, developing an education program, designing a successful business plan, and disseminating results for use by others. However, too frequently the design stage is ineffectively executed through disregard of community, environment or economics. Throughout the world there are many failed sanitation projects; this project targets enhancing performance, social acceptability, and sustainability of the ventilated improved pit toilet (VIPT).
A VIPT is a potentially sustainable technology that separates humans from excrement, thereby breaking potential disease transmission pathways. Improved ventilation reduces odor and minimizes flies, thus increasing social acceptability and reducing disease vectors. Flies transmit disease by landing on feces and then coming into contact with food or people. Previous research demonstrates that six air changes per hour (ACH) are required through the VIPT superstructure to reduce odor and flies effectively [4].
To increase understanding of the technical and social aspects of improved sanitation, partnerships were formed with Etta Projects, a nongovernmental organization (NGO) in Montero, Bolivia; The Carter Center; current Peace Corps volunteer Stephen Riutta; returned Peace Corps volunteer James Dumpert; and Dr. Kari Henquinet, in the Michigan Technological University Department of Social Sciences.
The research conducted by the Michigan Tech EPA P3 team involved the multidisciplinary design, monitoring, and modeling of a VIPT. A full-scale model of a VIPT was constructed to test airflow under various conditions. Using the data from the physical model, a computational fluid dynamics (CFD) model was validated and used to test other superstructure and pit geometries. Additionally, to engage potential users in the design process, a survey was developed by the Michigan Tech P3 team and delivered by project partners in potential implementation communities in Bolivia and Ghana.
Summary/Accomplishments (Outputs/Outcomes):
Community-Based Design Survey
Ten families were surveyed near Montero, Bolivia. Families typically use shallow pit latrines that flood during the rainy season, which forces them to practice open defecation. No outside organization has introduced a large-scale sanitation project in the community, and all existing latrines were constructed by the families.
The families expressed an interest in reducing flooding, flies, odor, and danger to children and livestock (falling into the pit). Other desired improvements to their toilets include adding a roof, brick walls and a ceramic toilet; however, they lack the financial means to obtain these materials. Additionally, 9 of the 10 families reported that at least one member of the household had suffered from diarrhea in the past 3 months; introducing improved sanitation could reduce that number.
The survey results from Ghana revealed common themes. People desire a toilet that is “clean,” lacking flies, and aesthetically pleasing.
Field-Scale Prototype
Wind speed, temperature, and solar radiation can all impact the airflow in a VIPT. The field model was created to measure the impacts of wind speed and temperature. By testing a VIPT under varying environmental conditions, an optimized design can be developed.
Three different ventilation pipes (4-, 6-, and 8-inch diameter PVC) were tested using a field-scale VIPT superstructure and pit. It was determined that the 8-inch pipe provides adequate ventilation with wind speeds ranging from 0.1-5.39 mph. The 4- and 6-inch pipes require wind speeds of at least 4.75 mph. Figure 1 displays the relationship between wind speed and ACH over a 30-hour span. Ventilation through the superstructure was lowest at night, even though the lowest wind speeds were recorded between 7:00 a.m. and 10:00 a.m. on Day 1. This demonstrates that other factors, including buoyancy and wind direction, impact ventilation.
Conclusions:
Monitoring a field-scale VIPT model under various conditions and performing CFD simulations revealed that the pipe used in a VIPT must be scaled based on wind speeds. Additionally, a spiral is the ideal superstructure shape as long as the door faces the prevailing wind. Due to constructability issues, however, this design is recommended only in regions where the structure will be constructed of mud or moldable material; otherwise, a standard rectangular shape is recommended. In flood prone areas the design should be modified to combine the ventilation benefits of a VIPT and the ecological principles of a composting toilet. This prevents wastes from contaminating groundwater, in addition to protecting surface waters during floods or periods of heavy rain.
Any improved sanitation project also must consider the cost and social acceptability of the project, ideally integrating community input into the design of the technology and support systems (e.g., education programs, maintenance). Surveyed families revealed that in addition to minimizing odors, they desire an aesthetically pleasing toilet. The definition of aesthetically pleasing varies depending on location; therefore, the ideal design needs to consider community customs, needs, and desires.
Proposed Phase II Objectives and Strategies:
Applying the knowledge gained from the Phase I project, a VIPT implementation plan has been developed. Two target communities, located in a peri-urban region near Montero, Bolivia, were chosen due to the strong partnership that has been formed with a local NGO, Etta Projects. Currently, the communities primarily use standard pit toilets, which fill with water and overflow during the rainy season, flooding the surrounding areas. Consequently, this allows the waste to come into direct contact with residents and their drinking water, thus eliminating any potential health benefits resulting from the pit toilets.
To ensure success of this comprehensive sanitation project, partnerships with two organizations have been formed. Etta Projects has been working in the communities for 7 years. The second partner is the Michigan Tech student chapter of Engineers Without Borders-USA (EWB). EWB and Etta Projects designed and implemented a low-cost water filtration technology in communities outside of Montero that has reduced reported stomach-related illness by 95%. The two organizations have worked together over the past 4 years, and are established in the community and trusted by residents. This will increase the chances of long-term success for the implementation project. Table 2 outlines the implementation plan for the project.
References:
- WaterAid. 2009. 1 March 2010 <
Journal Articles:
No journal articles submitted with this report: View all 3 publications for this projectSupplemental Keywords:
Ventilated Improved Pit Toilet (VIPT), Appropriate Technology, Improved sanitation,The 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.