Fluoride Action Network

Final Report: The Development of an Indigenous Fluoride Filter

July 31st, 2008 | U.S. Environmental Protection Agency

EPA Grant Number: SU833551
Title: The Development of an Indigenous Fluoride Filter
Investigators: Cumberbatch, Toby , Ponce, Beatrix , Batiir, Blandina , Berger, David , Atipoka, Faustina , Momade, Francis , Ayamgah, Gilbert , Freed, Leah , Volk, Lindsay , Nyarku, Michael , Pervez, Nadia , Rana, Sikha , Venugopal, Varsha
Institution: The Cooper Union for the Advancement of Science and Art , Kwame Nkrumah University of Science and Technology (KNUST)
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: P3 Challenge Area – Safe and Sustainable Water Resources , Pollution Prevention/Sustainable Development , P3 Awards , Sustainable and Healthy Communities


The World Health Organization deems water non-potable if it contains fluoride ions with a concentration greater than 1.5ppm. The objective of this research is to develop a truly sustainable filter for the removal of fluoride ions from groundwater that can, in principle, be used worldwide. Principal requirements for the filter are that, where possible, it uses indigenous materials for both the housing and filter media, and that the design be potentially accessible by all. It is our intent that neither skilled labor nor specialized components be required for construction of the filter housing, and that the design of the filter be available through a set of simple drawings and instructions for construction. Since, the most important component of any filter is the material used to remove the undesired chemicals or particulate matter, the adsorption media should be indigenous, freely available and not require special preparation in the form of chemical treatment or high temperature processing.

The problem of fluoride-contaminated groundwater in Bongo was encountered during a trip to Ghana in summer 2005. The straightforward nature of the problem matched Cooper Union’s limited resources and work on this topic began in fall 2005 under the auspices of the Center for Sustainable Engineering, Architecture and Art – Materials, Manufacturing and Minimalism. The problem also provided an ideal opportunity to introduce engineering students to the concepts of sustainability, minimalist engineering and the profound need to adopt a holistic approach to engineering design. Being located in the developing world, this project extends student awareness to thinking about approaches to seeking engineering solutions for those at the base of the pyramid. The outcomes of this early work were an identification of the methods used for the measurement of fluoride, and the identification and preliminary characterization of potential filter media.

During our visit to Bongo in summer 2007, the Bongo District Assembly built a small water laboratory for this project containing a borehole that provides us with a plentiful supply of water containing fluoride with a concentration greater than 1.5ppm, and a secure space to store equipment and undertake experiments. More importantly, it gives us the opportunity to monitor any changes in the fluoride concentration throughout the year. We had hoped that this series of measurements would be well underway by now but serious flooding across Northern Ghana in August/September 2007 put the laboratory underwater and a faulty pump precluded further experiments. When the PI visited Bongo in January 2008, he found the laboratory in excellent condition – all our equipment and instrumentation was intact. He replaced the faulty pump thereby enabling our local collaborators to establish procedures for routine water sampling – we have since purchased a higher capacity pump to take back with us this summer, to enable us to better simulate community use of the borehole.

In the short-term, the objective is to design a filter for the removal of excess fluoride ions from contaminated groundwater found in the Bongo District in the Upper Eastern Region of Ghana. A successful filter prototype will reduce fluoride concentrations from 5 ppm to below 1.5 ppm. Longer-term objectives include adapting the design for use throughout the developing world, especially by remote rural communities with very low income and the urban poor.

Summary/Accomplishments (Outputs/Outcomes):

Given that an essential component of the design is that it can be adapted for use throughout the world, the potential media investigated are those available in the regions containing fluoride contaminated groundwater. From the literature, wood charcoal, bone char, laterite and Moringa oleifera seeds were identified as potential media. To test the efficacy of these materials, it is self-evident that the most important procedure in this research is the accurate measurement of the concentration of fluoride ions in aqueous solution. For use in Northern Ghana, the method needs to be portable, require a minimum calibration procedure and ideally provide data under conditions of constant flow. We list below our major findings and outcomes:

  1. We have developed a reproducible procedure for the measurement of the free fluoride concentration in aqueous solution using an ion sensitive electrode (ISE). The electrode has a built-in preamplifier and a platinum resistance thermometer enabling correction for temperature. We have found that the ISE offers a reliable, efficient and robust solution for this measurement.
  2. During the development of this procedure, we have come to understand the nuances of the ISE and therefore believe that we are in a position to cope with, account for, and correct any unexpected behavior during our field investigation.
  3. We have developed procedures to characterize potential filter media using column and batch processing. We have found that particulate forms of laterite (from Pennsylvania and Bongo) and wood charcoal, and crushed Moringa oleifera seeds are all able to reduce the concentration of free fluoride ions in aqueous solution: the most efficient being laterite and the least efficient being charcoal.
  4. We have found that the magnitude of the reduction in fluoride concentration, after exposure to these materials, increases with decreasing particle size. We believe this indicates that the fluoride is removed from solution through a physio-chemical adsorption process.
  5. We have found that laterite and Moringa satisfy the requirements that potential adsorption media be indigenous and economic. We have also found that these materials do not require special preparation prior to their deployment as adsorption media. Bone char has been rejected for this part of the investigation since the communities, for whom the filter is being designed, consume little meat. Wood charcoal, never considered a serious candidate, for reasons of deforestation, was included to provide a standard since the absorptive properties of this material are well known and it can be obtained in pure form. We are in the process of replacing the wood charcoal with alumina for a standard.
  6. A design for a different culture and people is of little use without input and feedback from the stakeholders. Working with faculty and students from KNUST and a community in North Eastern Ghana, we have been able to learn something of the ways in which people in very poor, remote rural communities actually use water. They are teaching us about the technology gap that exists between them and us; we are learning about their preferred requirements for a water filter, their preferred procedure for recharging the filter media and have been able to observe at first hand, their usage of water.
  7. Working with the agencies and communities in Bongo, we believe that we have the necessary ingredients to develop an indigenous, sustainable filter for the removal of excess fluoride ions from groundwater. By the end of the project period, we intend to have prototype filters in use by the Bongo community – the quantity and type will depend upon the outcome of impending characterization of potential media and the logistics of monitoring their behavior. Based upon our preliminary findings we anticipate achieving our filtration goal of reducing 5 ppm to below 1.5 ppm.


Engineering for the poor often comprises the adaptation of established solutions from the developed world to satisfy a perceived demand in the developing world; this approach takes into account neither the real needs of the intended user nor the operating environment in which the solution is implemented. Such errors are further compounded by the distribution of these solutions in the form of “aid” in which the issues of sustainability are rarely addressed – and that are usually devoid of the principles of socially, economically and environmentally responsible entrepreneurship. The net result, so perfectly described by Ian Smillie in “Mastering the Machine Revisited: Poverty, Aid and Technology” is that “… too many failures in the ‘development business’ have been ignored or covered up, condemning poor people to suffer the re-invention of too many wheels that never worked in the first place.” William Easterly, in “The White Man’s Burden,” forcefully argues that the developed world can help Africa emerge from poverty by providing the poor with the means to establish their own self-reliance and, through this, gain their own self-determination.

Although we hope that the filter will be free in the sense that it can be constructed without specialized materials, tools or knowledge, an infrastructure will be needed to provide and dispose of the filter media, to monitor the properties of the filter, and to educate potential users in the construction and operation of the filter. In other words, the filter will generate employment opportunities. By incorporating the elements of entrepreneurship and business into the design process, these students gained insight into the constructs of real world sustainable engineering and the outcome of minimalist design. To establish a self-sustaining market, the filter has to be such that the members of these impoverished communities will actually want to install a filter, priced to cover the real cost. Thus the filter has to be sufficiently attractive, as a quality-of-life­enhancing product, for people to choose to forego their income in order to acquire a potable source of water.

The students were required to create an all-embracing design to satisfy stringent sustainability, engineering, and business criteria. When forced to implement these requirements simultaneously, the students gained an appreciation of the conflicting demands present in cross-sector programs, and the essential interplay and interdependencies of the multidisciplinary inputs into the design, launch, marketing and sustainable demand that are required for the successful introduction of a new product. They are beginning to understand the role of unadorned entrepreneurship in new business ventures. Working in emerging markets, the students see the critical function of micro-financing, the benefits gained by sharing the cost of expensive resources, the crucial importance of including the end-user in the design process, and the need to understand and characterize the environment in which the product will be used.

The students also had to consider the potential ancillary consequences of their work. Easier access to potable water in itself cannot alleviate poverty or provide food. However, by reducing the considerable amount of time spent by women and children collecting water from distant locations, the filter can enable children to spend more time at school and provide more productive work time for the women; furthermore, its local fabrication and distribution can provide some economic advantages, thereby leading to greater self-determination. The students learnt that any project of this type must proceed with caution, with transparency and community partnership being critical to its success. They also learnt that, underlying any presumed benefits, are profound questions about lifestyle, community, family, culture and traditions.

Cooper Union students in the disciplines of chemical, civil, and mechanical engineering who worked on this project in the US received training and insight into the rigorous demands of engineering for developing nations. As did those who went to Ghana last summer, the next cohort of students who go to Ghana this coming summer will learn what it means to live in another culture as an outsider and how people from different cultures frame questions differently. They will work in a different “engineering” milieu, where education, practices, and methods are often constrained by a dramatic lack of resources. Working with their Ghanaian colleagues, the students learn to design using a minimalist approach that incorporates input from the stakeholders, and utilizes indigenous resources and techniques. They will learn to derive solutions to basic problems that have the potential to improve the day-to-day life of thousands of people in rural communities throughout the developing world – and which may provide insight into ways in which the developed world can better utilize its resources.

Proposed Phase II Objectives and Strategies: The ideal outcome of Phase II is that all the residents of the Bongo District, currently affected by fluoride contaminated water, gain access to potable water with fluoride concentration < 1.5 ppm. The filter will ideally satisfy the criteria discussed previously – that it be easily constructed using indigenous materials and be available to all who need it. For this project to succeed, the community must be an integral part of the design and development process – continuous feedback and interaction are essential. Building upon the cordial relationship we already have with the community, the CWSA and the District Assembly, we do not anticipate any difficulties in achieving this.

The work to be completed can be split into three broad categories: technical aspects of the filter, design of the filter, and the implementation, operation and maintenance of the filter. The fluoride adsorptive properties of laterite and Moringa will continue to be investigated to establish reaction rates, media capacity, and reproducibility and possible media regeneration processes. Using the procedures we have developed in New York, we will measure the properties of laterite from many areas of the Bongo District, in addition to those of Moringa, also available locally. From these data we will be able to establish optimum particle size, water flow rate (retention time) and approximate capacity of the filter. In conjunction with these studies, parallel investigations must cover material procurement and preparation, material sanitization – and disposal – should it not be practical to regenerate the media. We intend to pursue approaches that use the materials in their most easily available state thereby obviating expensive preparation procedures. We do not preclude the use of sunlight (for sterilization) or manual labor since these resources are easily available and would provide local employment. We envisage the need to develop a procedure to measure the “quality” of the media thereby ensuring that the materials meet a baseline standard. As is easily imagined, a great deal of this work will take place in Bongo and require supervision by colleagues from KNUST.

Of special importance is the development of a cheap procedure for the determination of media activity or fluoride content of the processed water. It is likely that simple media preparation procedures and material variability will yield filter media with a range of properties making it difficult to set precise fluoride removal capacities per unit volume or weight, or type of media. The procedure should not require expensive precursors or equipment; ideally it will be a simpler precipitation reaction – with a yes/no result.

It is not currently possible to be very specific about the design and construction of the filter housing. As already mentioned, more data are needed to characterize the potential media and we believe it would be foolish to commence a design without critical input from the communities. Some of the questions to which answers are required include: Do the characteristics of the filter media allow for an inline removal system of fluoride at the borehole? Is it necessary to filter all the water – or only that used for cooking and drinking? Should it be determined that a small batch filter is practical or preferred – should there be one filter for each household or should there be one for a cluster of families? How will the operation and behavior of the filtered be monitored during the development phase? We intend to answer these questions during our summer visit this year.

With this information, and in consultation with the local community and organizations, preliminary specifications for the filter housing can be established. We feel that it is critically important that the fundamental ideals of the project not be lost during this process. Ensuring that the housing maximizes use of indigenous materials and minimizes the incorporation of imported components will make the design process more difficult but it should ensure that the original ideals are not lost – and that the community has ownership of the solution.

We are confident that we can initiate the development process during our two-month sojourn in Bongo this upcoming summer. For the remainder of the project, development of the filter will be a continuous evolutionary process as data from the different aspects of its operation become available.

As the media preparation procedures become more well defined, and the filter operating and maintenance procedures more refined, the filter design will start to stabilize and will be exported to neighboring communities in the Upper East and Northern regions of Ghana with similar problems. Documentation will be prepared and distributed that provides unambiguous instructions for all aspects of filter construction and operation.

Ideally, the project will conclude with export of the design to other areas in the world where poor communities need a solution to the problem of excess fluoride in groundwater.

Supplemental Keywords:

RFA, scientific discipline, sustainable industry/business, media, treatment/remediation, environmental engineering, sustainable environment, technology, public policy, drinking water, groundwater, fluoride, toxics, clean technologies, health effects, human health, children, environmentally conscious design, community based, base of the pyramid,

Relevant Websites: http://www.ee.cooper.edu/sea2m3/africa/filter

*Original online at https://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract_id/8619/report/F