Grantee Research Project Results
Final Report: Sustainable Community Development – Water Slow-Sand Filtration
EPA Grant Number: SU833544Title: Sustainable Community Development – Water Slow-Sand Filtration
Investigators: Bland, Larry , Alvarez, Claudia , Ruiz, Javier , Soberanis, Luis , Young, Preston , Mitchell, TJ , Kim, Young-Gurl
Institution: John Brown University
EPA Project Officer: Page, Angela
Phase: I
Project Period: August 31, 2007 through July 31, 2008
Project Amount: $10,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2007) 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:
The proposed research project question is: “How can a slow-sand water purification system be improved to meet the needs of a small community?” A major issue that persists in underdeveloped areas is both water quality and quantity. There have been point-of-use water purification systems developed that can provide for particulate removal, bacteria destruction, or both. However, large-scale community systems have remained too expensive for underdeveloped communities. This project has three objectives: 1) characterize slow-sand filters in an environment exceeding that of the target communities, 2) research and test methods that could provide increased output, and 3) develop concepts and plan for the system waste to promote sustainability. The Phase I project was divided into four components to meet objectives: a) site survey to understand the people, their local capabilities and what may be needed to make this project both successful for the perspective of water improvement and sustainable for the long-term; b) build and characterize a slow-sand filter; c) determine an augmentation system that would provide higher flow rates without compromising water quality; and d) evaluate the filter cleaning process looking for a micro-enterprise that would stimulate sustainability.
Summary/Accomplishments (Outputs/Outcomes):
Site Survey: When this project was developed, the village of Santa Cruz, Baja Verapaz, Guatemala was chosen as a target community for initial development and target implementation. The research team of six students and advisor traveled to the village in early August 2007 for a site survey. Shortly after arriving at the village, we were provided a written report from Plan Guatemala that provided valuable data. A water collection and distribution system was built for the village some years ago using United Nations funding. The storage tank has a storage capacity of 46.2 cubic meters. The vertical drop from the mountain catchment area to the holding tank is 520 feet. This creates a significant hydraulic energy source that is currently unused. Local data and testing showed that their water contains bacteria and is unfit for human consumption.
The team also evaluated the local technical skills and available resources. The local construction consisted of concrete, concrete block, wood and corrugated metal. Sand was found in abundance. These items are directly compatible with the chosen slow-sand filter. Even though the area is tropical in latitudinal location, the mountains create a cooler environment and the August water temperature at the source was measured at 16 degrees Celsius. This temperature will be colder in the winter months and therefore biological/algae growth will be slower than originally expected. Electricity was found to exist at almost every home in the village. Power was limited as there was a single 110-volt line, 15-amp service. The electrical service also demonstrated a fees collection system as each home pays a very low flat rate to maintain this service for their community and home.
Slow-sand Filter: The JBU filter system began with creating a water collection system that closely simulated the environment at Santa Cruz. A water run-off creek runs through our campus and adjacent to our research lab. An analysis of our operating conditions showed that our lab set-up had harsher environmental constraints than those in Guatemala (GUA). Water source turbidity in GUA was less than 5 NTU (nephelometric turbidity units). JBU source was 10-30 NTU. Water temperature was 16 degrees C. in GUA and 8-12 degrees C. at JBU. Growth of the Schmutzdecke was slower than anticipated, but does take place even in this colder environment.
For outcome evaluation, the team chose to use measurement techniques that could be easily transferred into impoverished communities. For measuring the turbidity of the water, a simple graduated cylinder was used. The turbidity tube uses the correlation between visibility and turbidity to approximate a turbidity level. A marker is placed at the bottom of the tube and fluid poured into the tube until the marker can no longer be seen due to the “cloudiness” of the water. This height correlates to a known turbidity value. Though this measuring technique is very basic, it does represent a technology that is readily transferred as an appropriate process to communities like Santa Cruz.
For bacteria analysis, Hach’s PathoScreen™ test was used. The testing has two process to determine presence/absence (P/A) and most probable number (MPN). The technique is well-suited for monitoring drinking water systems in developing tropical countries and remote field locations. The World Health Organization looks to this type of testing for impoverished communities with the criteria that no bacteria colonies be distinguishable after 48 hours of P/A incubation. As the Schmutzdecke was developing in our laboratory system, measureable reductions in bacteria were noted. Bacterial levels reached acceptable levels as the depth of the biological layer reached 7.5 cm. and the flow rate reduced to about one gallon/minute/square meter. All source samples indicated significant bacteria within 24 hours of incubation while outputs began to show no bacteria in medium at 72 hours.
Augmentation System: As a result of the site survey, it was apparent that there were augmentation opportunities. As noted earlier, the current delivery pipe from the catchment point to the holding tank has significant hydraulic energy due to the vertical drop. This information provided opportunity to considered power generation techniques, adding external purification devices, and injection of additives for purification.
To provide water purification, the electrical energy must be converted into an energy source that would kill bacteria. In a short trip outside of Santa Cruz, the project team observed UV lighting being used for purification. Materials are available. Minimal training would be needed for operation and maintenance. A quick analysis shows that fast filtration to remove solid particulates combined with UV light could provide for safe drinking water. The creek water was first run through a sediment filter to remove particulates. The next task was to characterize a UV system at various flow rates ranging from 50% of manufacturer’s ratings to 150%. The bacteria were effectively eliminated even at 150% of rating. We now have data from both the sand filter and the UV system that show encouraging promise for integrating the two approaches during Phase II.
Filter Cleaning: The final element of Phase I research is the slow-sand filter maintenance. The slow-sand filtration system requires continual maintenance for sustained operation. If the biological layer is not trimmed/scrubbed on a regular basis, the system flow will reduce, which negates any improvements in the flow achieved by this project. Two issues arise from this requirement: 1) the need for someone willing to accept the maintenance responsibility and 2) environmentally-friendly disposal of the trimmings. To solve both of these problems, the project team considered both technical issues and a partnership with Students in Free Enterprise (SIFE), an NGO, for implementation considerations.
From the technical side, the basic task removes a layer of sand and Schmutzdecke from the top of the filter, separates the sand and the biological material, places the sand back in the filter and looks for an environmentally friendly and economic way of disposing the biological waste product. During Phase I, system operation required the removal of the biological layer after three months of operation. Approximately 2 cm of this layer was removed yielding just over 24 pounds of sand and with about 9% by-product by weight. The sand was separates from any nutrients using a simple wire screen and shaking. Recovered nutrients were available for usage in micro-enterprise development.
The technical team has partnered with Students in Free Enterprise (SIFE) at John Brown University. SIFE has five active teams working on multi-year projects in Central America. Members of the research team are also members of SIFE. The primary consideration for Santa Cruz is to use the system trimmings as fertilizer in local gardens. With per capita income in many of these communities of only $70-80 per month, a small business can have significant incentive and impact on the local economy.
Conclusions:
From the Phase I research tasks, we have characterized slow-sand filter operations, shown that the biological layer can be effectively grown in colder water environments, evaluated augmentations systems with technical performance data and sustainable implementation concepts, developed relationships with communities for transfer of technology and community training, created a concept for sustainable system maintenance, by-product recovery and beginning micro-enterprise development.
Pure water provides obvious quality of life improvements. Communities in Baja Verapaz have told the team that 2-3 children were dying monthly due to waterborne diseases. Individual sickness due to the waterborne issues will be greatly reduced. Children death rates will be reduced. Healthier workers will increase productivity and monetary income for their families. Healthier students will result in better attendance in schools and hopes for a better future as education levels increase and ability for more productive future generations develop.
Project Period for Phase II: August 2008-July 2010
Proposed Phase II Objectives and Strategies:
As the project moves into the second phase of research and implementation, the project team will continue a) to explore additional augmentation opportunities, b) integrate slow-sand filters and augmentation to provide greater efficiencies while maintaining pure water production, c) implement training and sustainable transfer to the communities, and d) design and build a final system for the community of Santa Cruz, Baja Verapaz, Guatemala.
The first tasks builds on current research in oxygen remediation systems that call for pure oxygen and mechanical injection and dispersement systems. It is intuitively obvious that pure oxygen would be more efficient than our normal air that has a concentration of 19-21%. But for impoverished communities, maintaining a supply of pure oxygen is not a reasonable requirement for sustainable operation. But the normal atmospheric air is available at no charge. The hydraulic pressure would be used to drive an air pump. Instead of the oxygen being viewed as the primary remediation agent, this project would measure the affectivity of coupling air (oxygen) injection with the functions of the slow-sand filter. The goal would be to determine if data would support the generation of higher flow rates per surface area while maintaining potable water output. The research would evaluate a distribution system placed under the gravel and sand layers and experiment with multiple methods to use the natural reactions within the sand bed to break down the air to smaller bubbles and distribute throughout the filter.
The second task of Phase II is to develop an integrated system that meets the throughput needs of a community, reduced size and expense for higher probability of acceptance into impoverished areas, and is fully sustainable using locally available skill, materials and knowledge. Phase I looked at filters and UV in stand-alone evaluations. Phase II would integrate techniques. It is envisioned that the final design will be adaptable to many communities around the world. It is also recognized that communities will have highly diverse skills and knowledge base. A targeted outcome from the Phase II research is a matrix of potential integrated solutions that could be adapted around the planet. Some areas may only have the ability to sustain a slow-sand filter. These may even have to be implemented at the point-of-use level. Other areas, like Santa Cruz and neighboring communities, would have the ability to utilize the infrastructure in place and integrate multiple systems such as sand filters and UV. Other communities may not be able to sustain UV and would possibly use the air injection. Phase II would test integrated systems, confirm their effectiveness to work together and create a matrix of designs for broad community level implementation.
The final two tasks are key to making this project sustainable. First, the project includes an educational component (offered through our partner NGOs) to train communities in both usage and maintenance so that the system is incorporated into local lifestyles. A key element of our project success is the training of the community to both change their habits developing better hygiene and to take full ownership of the water treatment process with construction, operation and maintenance. To assist in this effort John Brown University has developed partnerships with two NGO’s; the Institute for Biblical Community Development (IBCD) and Students in Free Enterprise (SIFE). IBCD has a proven track record of developing community projects around the world and successfully training local individuals for both usage and maintenance of appropriate technology solutions. The Institute will assist the research team in developing and implementing an educational plan with two key elements: 1) safe water usage and avoiding re-contamination, and 2) operation, maintenance and repair of the improved water purification system. SIFE has five active teams working on multi-year projects in Central America. For Guatemala, SIFE will assist the research team in developing a micro-enterprise plan to use the system trimmings as fertilizer in local gardens and generate a business that improves prosperity.
The SIFE organization has a history of working very successfully in Guatemala and Santa Cruz. Over the past year the team has been able to build on previous relationships. A Central American man and woman have moved to Santa Cruz to work on community improvement activities. A trash collection and sanitation program has already been implemented. Trust has been built with the people. Micro-loans have been provided to people and small businesses are emerging. The man in residence is also a retired teacher of Civil Engineering. This will be a strong asset in the construction and training for the final water system implementation. This type of effort will continue through Phase II and build to meet the need for potable water, economic development, improvement for the lives of the local people and an excellent, sustainable solution to meet a planetary need.
The final Phase II tasks is the construction of a community water system in Santa Cruz. This is an excellent opportunity to create jobs and develop community ownership of the process. The materials have already been confirmed as locally available. There are local artisans fully capable of meeting all of the construction needs. An individual is on-site with civil engineering skills to lead and sustain the process. Funds from this Phase II grant would be used for both construction materials and paying for local individuals to complete all of the tasks. A team of engineers from JBU will be present for both the construction and early operation. They will be working along side of the local people to provide encouragement and answer questions quickly. There primary goal will be developing trust and confidence while giving on-the-job training that will create a sustainable operation. NGO’s will assist with the training and sustainable transition to local operations.
Supplemental Keywords:
water purification, filtration, pathogenic organisms, disinfection, appropriate technology,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.