Grantee Research Project Results
Final Report: Rainwater Harvesting and Treatment System for the Delmas 30 Neighborhood of Port-au-Prince, Haiti
EPA Grant Number: SU834770Title: Rainwater Harvesting and Treatment System for the Delmas 30 Neighborhood of Port-au-Prince, Haiti
Investigators: Colosi, Lisa , Henriques, Justin , Andrukonis, Megan , McNally, Taylor , Jones, Kendra , Foster, Ben
Institution: University of Virginia
EPA Project Officer: Page, Angela
Phase: I
Project Period: August 15, 2010 through August 14, 2011
Project Amount: $10,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2010) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Sustainable and Healthy Communities , P3 Challenge Area - Safe and Sustainable Water Resources , P3 Awards , Sustainable and Healthy Communities
Objective:
The original goal of our project was to provide drinkable water for the community of Delmas 30 in Port-au-Prince, Haiti. Prior to receiving the P3grant, we had completed the design of a rainwater harvesting and treatment system to be constructed on site at a local community center that is the longest standing institution and the largest building in the Delmas 30 neighborhood of Port-au-Prince. In our original proposal we split the project into two parts. The first part involved: 1) testing the quality of the influent (rainwater in Haiti) and the effluent water through our system, 2) meeting with the relevant parties at the community center in order to hear their vision and goals for the project, and identifying how we could integrate our system into the current health care programs of the community, 3) meeting with International Action (an NGO who currently does chlorination projects in Haiti), and 4) sourcing the materials needed for the final construction of our system. The second part of the project involved the installation of the complete system and locating other locations for the potential implementation of similar systems. Less than two weeks after the original proposal was submitted, on January 12, 2010, a 7.0- magnitude earthquake struck just 16 miles from Port-au-Prince, Haiti, essentially destroying the city (USGS, 2010). Our partner in Port-au-Prince suffered significant organizational losses, and the community center experienced major structural damage (although not irreparable damage). We quickly realized that the organization in Haiti had more pressing issues and would be unable to support us in our work on the system. At the request of the EPA, we submitted an altered scope and budget in May 2010 to design, construct, and test a similar system in an urban environment in the US. The goal of this system is to test the original system design and functionally provide a multi-functional water system at its chosen location in the US.
The primary goal of Phase 1 is an improved rainwater catchment design for ultimate implementation in Delmas 30. Since the improved design will be determined by way of constructing and testing a small-scale system in an urban area in the US, a secondary goal of Phase 1 is providing this system as a multi-functional water system that betters its location in the US. Results from tests performed on the US system will serve to either confirm that our current Haiti design choices are sufficient to meet water quality standards or else highlight necessary revisions. With this information, we will be able to complete our design, which could then be constructed and used. The test results will also allow for calculation of more accurate maintenance cost estimates. Test results will also be extremely valuable for collecting performance information that is not currently available from vendors of individual process components.
Summary/Accomplishments (Outputs/Outcomes):
Given the design challenges and system component considerations, a two-tank system was designed to fit the Charlottesville residence. Rain capacity of the tanks totaled 750 gallons, which was decided upon according to rainfall intensity data for Charlottesville and the expected usage of the catchment system. A primary tank was elevated at a calculated height to act as the principal rainwater collector and provide the proper elevation drop (pressure) to the inline filters. The second tank was located on the ground near the elevated tank, providing overflow capacity once the primary tank is full. The structural integrity of the design was analyzed using ANSYS, a structural analysis software tool, to ensure that the structure could sustain the weight of a full tank of water and lateral wind loads. In addition, an elevated tower included carefully designed bolt holes to support various children’s play equipment such as a climbing wall or slide. The final design at the residence will not contain filters or a chlorinator, but instead will serve the functional purposes of the residents. These functions of the Charlottesville rainwater catchment system include gravity-fed irrigation of an urban garden, support for children’s play equipment, a gravel path for walking, and a spigot for a washing area. For purposes of effluent testing, the system can be adjusted such that water from the elevated tank could flow down through the filters and chlorinator into the second tank, where the water can be stored for testing purposes. The system could allow filter performance, chlorine dosages, and contact time of the chlorine to be tested. A sketch of the system is shown in Figure 1.
Figure 1 – Rainwater harvesting system design for Charlottesville
Due to time and budget restrictions, the system has not yet been built in Charlottesville. Ultimately a decision was made to eliminate the tower and move to an on-ground catchment system. Thus, the functional components of the designed harvesting system were simulated in laboratory experiments. For these experiments, rainwater was collected from a roof in Charlottesville, VA.
The inline filters (Calypso Big Blue Filters) were purchased and their operational efficiency was tested. Water was run through the series of filters with no observable pressure loss across the filters. A range of low flowrates were evaluated, with no apparent change in basic performance. From visual observation it was determinded that the filters are highly capable of handling the potential flow rates which they would experience in the Haiti design.
The operational consistency of the chlorinator (Norweco Bio-Dynamic Chlorine Tablet Feeder Model LF 1000) was evaluated using laboratory experiments. The rainwater was sent through the chlorinator at varying flow rates to determine whether or not the dissolution rate of the chlorine tablets changes as a function of flowrate. Hach Method 21056-69 was used in conjunction with a UV Visible Spectrophotometer (set to 515 nm) to measure total chlorine concentration is post-chlorinated samples. A calibration curve was produced using five standards with known concentrations of chlorine in DI water. From this curve, the concentration of the dosed rainwater samples was interpolated based on the linear relationship between absorbance and concentration. This relationship is depicted in Figure 2.
Chlorine residual was assessed for a variety of flow rates. Although the vendor indicated that chlorine concentration should not be a function of flow rate through the chlorination apparatus, there was a 20 mg/L range of chlorine concentrations above and below the average, 35.4 mg/L (Figure 3). This suggests that the chlorine tablets do not dissolve at a steady rate and are dependent on flow rate, despite the vendor’s assertion that the chlorine concentration should be the same for all flow rates. This relationship between dissolution rate and flow rate is unclear. However, the chlorine concentration reaches a maximum at a rate of ~6.5 gpm and decreases with higher flow rates. This maximum point may indicate an ideal flow rate for the chlorination system.
Based on the average chlorine concentration, only a portion of the filtered rainwater should be passed through the chlorination system when the system is being used to produce drinking water. According to EPA standards, the chlorine concentration in drinking water should be limited to 4 ppm. Therefore, only 10-20% of the rainwater should pass through the chlorination system, as expected. Contact time will be important in order to allow proper chlorination for the entire collection of rainwater.
Figure 3 – The variation in chlorine concentration with varying flow rate.
The total chlorine in the rainwater was measured immediately following the dose as well as 24 and 48 hours later to test persistence of the chlorine residual. After 24 hours each sample’s chlorine concentration decreased by roughly 10 mg/L on average. An additional decrease of about 10 mg/L is seen after 48 hours. Municipal potable water supplies are usually chlorinated to provide a residual concentration of 0.5 to 2.0 ppm (Edstrom, 2008). With 10-20% passing through the chlorination system, the residual chlorine will be well within this range. This suggests that the chlorinator originally selected for use in the Haiti system will be suitable for its originally intended use.
Conclusions:
The design of the catchment system both integrates the structure into the urban, residential environment, and meets the technical specifications required for evaluation. Rainwater harvesting promotes the efficient use of water resources, since it alleviates strain on other water resources, sewage infrastructure and water treatment facilities. Implementing the use of a residential-based rainwater catchment system has the potential to encourage water conservation in the developed world.
Although time and budget restrictions presented a major barrier to constructing the system, the key components of the system designed for Haiti were successfully tested. The results from testing indicate that the system is operational at moderate flow rates. This result is particularly important for the chlorination system. Since the water will be pumped into the chlorinator, low flow rates are ideal for use in an undeveloped country where the electricity is intermittent and unreliable. The system will be able to operate with minimal dependence on local power sources.
The innovative approach to cleaning rainwater through filtration and chlorination will increase the availability of clean water for basic needs. Access between 40 and 50 liters per day per capita is recommended to meet the basic requirements for drinking water, hygiene, sanitation, and food preparation. In Port-au-Prince, many residents live well below this requirement. The proposed rainwater harvesting system will undoubtedly lower the number of local residents living below this standard.
Aside from providing shear volume, the improved quality of the water source is essential for the residents of Port-au-Prince. The water supplies in Port-au-Prince are plagued by pathogens that pose innumerable health risks to consumers, resulting in historically high mortality rates throughout the country. The chlorination will lead to a significant reduction in water-related diseases suffered by consumers. The quality of life of the Delmas 30 community will hopefully improve drastically and measurably in a relatively short period of time.
Another benefit of the proposed system is its economic viability. The system will generate, through the sale of water, the revenue necessary for routine maintenance and operation, system upkeep, and the purchasing of replacement parts such as new filters and chlorine. The self-sufficient system will provide clean water at a fair rate, giving community members an affordable alternative to less secure, less reputable water sources in Delmas 30. Additionally, the system will lower the burden on the public water system by utilizing an untapped resource.
The system is remarkably sustainable. It will simply catch a free, un-owned resource— rainwater—that would otherwise flow destructively in the form of runoff into open sewers; and through the process of purification and sanitization, will make it into a value-generating resource that can benefit the local community and drastically improve the health of local residents.
Journal Articles:
No journal articles submitted with this report: View all 2 publications for this projectSupplemental Keywords:
human health, community-based, publicThe 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.