Final Report: Harvesting Potable and Storable Water with Moringa Seeds and SandEPA Grant Number: SU834740
Title: Harvesting Potable and Storable Water with Moringa Seeds and Sand
Investigators: Velegol, Darrell , Velegol, Stephanie B , Kaley, Bradley , Smith, Eric , McCollough, Lauren , Paskewicz, Mary , Schuhmann, Richard , Tzonev, Tzonu
Institution: Pennsylvania State University
EPA Project Officer: Nolt-Helms, Cynthia
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 - Agriculture , P3 Challenge Area - Water , P3 Awards , Sustainability
Moringa oleifera is often called the “miracle tree”. The tree is prevalent in equatorial regions, which often coincide with the regions of the world suffering from malnutrition, insufficient energy resources, and waterborne disease. Most notably, the seeds of the Moringa tree can be crushed to clarify and disinfect drinking water, but they are also a highly nutritious food source and a potential avenue for economic prosperity. Once the water cleansing ingredients are extracted from the seeds, valuable oils can be extracted from the remaining seed material for use in in cosmetics, cooking, biodiesel fuel, and livestock feed. Thus, while this proposal focuses on water treatment, the Moringa tree offers many additional benefits that can enhance people‟s health and prosperity while improving the health of our planet.
The seeds of the Moringa tree contain a natural, cationic protein that acts as a flocculant, decreasing the turbidity and removing negatively charged particles, including bacteria. The antimicrobial, flocculant properties of dried Moringa seeds are well established in the literature.
A key barrier limiting the use of this cationic protein is the non-functional organic matter that remains dissolved in the water when crushed Moringa seeds are added. This organic material adds “biological oxygen demand” (BOD) – food for the bacteria – to the water, which encourages bacterial growth and prevents the cleaned water from being stored for a period greater than 24 hours.
Our solution is to immobilize the positively charged protein on negatively charged sand. The spent Moringa seed matter can then be rinsed away from the protein-coated sand to eliminate the problematic BOD. The resulting functionalized sand (f-sand), which is shown by preliminary data to retain the disinfection and clarification functions for water, shows promise for use in a simple, sustainable water treatment process for the developing world. In order to develop a treatment process, we must answer important technical questions about the engineering, and pursue two key cultural and educational objectives
- Optimize the water purification process in the lab.
- Implement the process in the field
Objective 1: Optimize the Water Purification Process in the Lab
It was our objective to optimize the seed to sand ratio, in order to bring the project to the highest level of sustainability and economic viability. The optimal ratio was found to be 1 seed per 6 grams of sand, and the effectiveness of the f-sand was then tested with respect to the conditions under which it was used. Wet, dry, and aged f-sand samples were tested to determine their ability to remove turbidity from solution. Newly generated f-sand is wet; however it can easily be dehydrated. Thus, both wet and dry f-sand samples were tested for effectiveness and longevity. Each cleared the same amount of turbidity after 60 minutes; however, the wet f-sand was more efficient and worked much faster than the dry f-sand. After testing for longevity, it was determined that all samples, independent of age, were shown to clear a relatively equal amount of turbidity.
This implied that f-sand could be synthesized in one large batch and then stored for long periods of time, thus people would not have to spend time generating it regularly. Ideally, f-sand could be stored wet to maximize effectiveness, and the same sample could be used multiple times (until it was fully saturated with sediment). It was expected that wet f-sand, stored for longer than one month, would grow bacteria and mildew; thus, it was recommended that wet f-sand be stored and utilized within 3 weeks. However, for long-term storage, dry f-sand was shown to retain its integrity for up to 7 months.
Objective 2: Implement Process in the Field
An assessment trip to Tiout, Morocco was conducted to establish a relationship with the local people and to determine the actual water needs of the community. Upon inspection of the available water resources, it was determined that f-sand was not a good fit for the community. The local people relied solely on ground water and had no significant turbidity problems. Although there was likely some contamination of the drinking water due to lack of knowledge about the causes of water borne illness, f-sand would be of more assistance in a community with surface water and turbidity issues. Therefore, the team looked for a community that relied primarily on untreated, turbid surface water for drinking water.
After an assessment trip to Puerto Rico it was established that the community of El Duque in the Highlands area would be an ideal site for initial implementation. The community does not filter or treat the surface water collected in any way. As a result of the demonstrated need for a filtration system, the team decided to shift the implementation focus from an individual or household sized batch process to a filter that could accommodate larger volumes of water
Theoretical Design based on Experimental Data
The objectives of the f-sand filter design were as follows:
- Consider batch process data and design criteria to achieve a range of demonstrated effective residence time.
- Make the design adaptable based on variables including: water quality and quantity, locally available materials including piping sizes and sand grain sizes, and desired flow rate.
- Build a working prototype.
The proposed design was based on an experimentally determined effective residence time range of 20-60 minutes. The grain size of the sand affects the porosity and hydraulic conductivity of the media. For our sand, we experimentally determined the hydraulic conductivity and the porosity. These values are important in determining the parameters of filter design, such as the hydraulic head loss and volumetric flow rate.
Challenges faced with our early continuous flow filter designs included residence times much lower than the minimum 20 minutes, maintaining a constant hydraulic head, and keeping extremely fine sand grains from exiting the filter with the effluent. We found that packing the sand while wet eliminated the sand breakthrough problem. Our next design iteration incorporated a clear PVC pipe packed with wet sand, and utilized a substantially lower hydraulic head to decrease flow rate in order to increase residence time.
Our current prototype is a point-of-use filter designed to maximize kaolin removal within the constraints of the competition space. We have incorporated an outlet valve into the design so we can control the residence time making filter size irrelevant. We intend to build and test this design for turbidity clearance prior to the EPA P3 competition.
Other options we considered included adapting the design to be a slow sand filter. One advantage to a slow sand filter would be that the sand would not even need to be sieved to isolate particular grain sizes. The physical filter parameters such as cross sectional area and length could also be adapted to achieve higher times while preserving continuous flow. In some cases, the batch method of rolling raw water with f-sand might even be best. The ultimate goal is that we gain an increasingly better understanding of the water treatment capabilities of Moringa seeds, so we can formulate a design process that can be applied anywhere the tree grows.
During the initial assessment trip to El Duque, it became clear that introducing Moringa and f-sand would not only contribute to the physical health of the community, but would engage the people, protect the planet, and provide opportunities for increased prosperity. The residents of this community do not recognize that the condition of their water has the potential to make them sick. Because of this, there is no way to quantify how many people are becoming ill from the condition of the water as opposed to other common sources of diarrheal illness. Implementing an f-sand treatment process would eliminate the illnesses that are caused by the water contamination.
An initial implementation in El Duque would also provide a unique opportunity for two-way learning to occur between the people of the community and the Penn State Team. While we have much to share about the benefits of Moringa, f-sand, and water treatment, there is even more that we can learn from the people of the community. This will be an opportunity for open and honest discussion about the needs of a small rural community and the benefits and drawbacks of certain prototype designs. This knowledge can then be transferred to other similar global communities.
Using all natural f-sand to treat the water in El Duque rather than conventional alternatives would protect the planet by eliminating hazardous chemicals. The byproducts of f-sand production and use include only crushed Moringa seeds and sand. The sand can be stripped of proteins through UV exposure from the sun, and the crushed Moringa seed is easily biodegradable and used for a number of different products. This process is completely natural and completely sustainable by the members of the community in which it is implemented. In fact, the addition of Moringa trees would add beauty to the area and benefit the environment. Water treatment with f-sand is sustainable from start to finish.
The community does not have the financial resources necessary to install a water treatment system that would meet the EPA standards, and as a result, they are fined $25,000, an amount that the community will never be able to pay. Production of Moringa oleifera has many economic benefits in itself. The crushed seed byproduct of f-sand production can be pressed for oil which can be used as a biofuel or in cosmetic products. Also, the crushed or powdered Moringa leaves have extreme nutritional benefits.
f-sand as an Educational Tool
Since we began work on Phase I, two groups of Penn State University students have been involved through three separate academic programs, and five academic majors were represented in Fall 2010. The current team consists of both chemical and civil engineers.
Members of the Moringa team also visited a 5th grade class, gave a demonstration of how f-sand works, and talked with the students about the problems caused by unsafe drinking water in Puerto Rico. The students decided they would develop a wordless document to teach others around the world how to make and use f-sand. (We plan to bring this document to the P3 Expo in April.)
Optimize the water purification process in the lab
- Turbidity (kaolin) was cleared from solution using an optimized ratio of 1 seed per 6 g sand
- f-sand stored wet was shown to maintain its effectiveness (clearing turbidity for 60 minutes) over a length of 22 days
- Dehydrated f-sand was shown to be storable for up to 7 months without any negative effects on integrity or efficacy
Implement process in the field
- Puerto Rico was determined to be the most pragmatic location for the initial implementation of f-sand technology due to current SDWA violations; local relationships were formed to provide technical and cultural consulting
- A prototype point-of-use sand filter with adjustable residence times was designed for bacteria and turbidity removal
Educational dissemination of information:
- Penn State University undergraduate students from three academics programs and five different majors were educated in research, culture, and design principles via collaboration on this project
- Elementary students were educated about culture and the basic science of Moringa through an interactive classroom demonstration; the collaboration continues as they are creating a wordless manual explaining the procedure for f-sand utilization