Final Report: Drinking Water System for Developing Countries / Disaster Relief Made with Local MaterialsEPA Grant Number: SU835531
Title: Drinking Water System for Developing Countries / Disaster Relief Made with Local Materials
Investigators: Hestekin, Christa , Cole, Lauren , Durant, Keiron , Goss, Jordan , Hasan, Shumon , Lee, DJ , Penney, Roy , Qasem, Omar , Schulte, Stephanie , Serrano Castillo, Florencio , Tichy, Cayla
Institution: University of Arkansas - Fayetteville
EPA Project Officer: Levinson, Barbara
Project Period: August 15, 2013 through August 14, 2014
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2013) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Water , P3 Awards , Sustainability
The United Nations estimates that water-borne illness accounts for 80% of deaths in developing nations and that nearly 1 in 6 do not have access to clean water (1). However, despite the ability to produce water in the developed world from complex streams such as wastewater or seawater, challenges remain in providing this basic resource in the developing world. Too often the approach has been to apply a high-tech solution, which requires significant technical expertise to run and significant financial resources to repair. Furthermore, as every developing nation faces different challenges, a new solution must be provided for each situation.
The objective of this project was to design a water purification system that can be constructed from easily available materials, common to the particular country, and is capable of the complete water purification process. The designed system consisted of a treadle pump (built from wood or bamboo) to pull the water from its source, a filter (made of readily available materials such as sand) to remove contaminants and improve palatability of water, an electrolysis system to allow chlorination from salt water (using locally sourced salt), and a car battery (which could be sourced from a scrapped car) that could be charged by pedaling a mountain bike connected to a DC motor (which could be obtained from a scrapped scooter). In addition, a set of instructions was developed that can be interpreted with minimal text. In Phase I, a working model and the schematics of the system were developed and tested. In Phase II, the schematics will be taken to a developing nation, India, and a water purification system will be built and evaluated on site. The schematics will be modified according to the ability of locals to understand and construct the system and schematics will be developed for other developing nations with different material resources. Depending on the success of the project, additional funding will be requested to distribute these instructions to as many developing nations as possible.
The Phase I research team, Team WaterHOGs, sought to design a simple water purification process that would clean water from alternate sources. One innovation of this system was the novel combination of previously demonstrated technologies into one system that can take water from untreated non-potable water to drinking water. Another unique innovation was the development of a set of instructions that could be used anywhere in the world with locally sourced materials and with minimal use of text. Due to the nature of this technology, the water source must be freshwater (i.e. no ability to turn seawater into drinking water) and chemical contaminants (i.e. PCBs, heavy metals) will not be removed. A higher tech approach would be able to handle seawater (i.e. reverse osmosis system or solar distillation), but at the cost of higher material and energy costs. Since most of the developing nations are dealing with water contaminated with fecal matter, the technology is focused on eliminating microbial contaminants (2). In addition, low technology solutions often provide a longer lasting and less waste-producing solution (3).
Team WaterHOGs first sought to determine what types of water compositions the intended process could handle. Through extensive research it was determined that the system should be primarily targeted towards water supplies contaminated with microbial agents, but with moderate levels of salinity, and no chemical contaminants.
The single person treadle pump was constructed primarily using standard 2”x 4” wooden beams. The piston system was built from standard 4 inch diameter PVC pipe. A support system was designed, using additional 2”x 4” wooden beams to stabilize the main structure of the pump, and minimize friction losses. The final pump used two pistons and was capable of producing 12 psia of head per piston when operated by a 160 lb person. This generated a flow rate of 5 gallons per minute. The wooden beams and PVC pipe could be replaced with local materials such as bamboo.
A sand filter was designed to removed large contaminants and other suspended solids present in the well water. The filter was designed using an 18 gallon plastic bucket open to the atmosphere. The filter contained layers of sand, coarse gravel and cloth. The water was pumped into the top of the filter using a single piston, where it flowed down the filter material, and was collected at the bottom of the bucket through a two inch PVC tube connected to the second piston. Theoretical analysis and experimentation confirmed that the pressure head and volumetric flow rate are not significantly affected after the water flows through the filter. The PVC pipe and plastic bucket could be replaced with local materials such as bamboo and pottery.
In order to obtain the energy required to power the entirety of the process, Team WaterHOGs designed a human powered electric generator. The generator was built from an 18 speed mountain bike, which was hooked up to a DC motor. This motor was attached to a 12 volt car battery; as long as the bicycle was being pedaled fast enough (>1000 rpm), the battery will be charged. This battery was used to power the electrolysis unit. Testing confirmed the ability of this system to recharge the battery. The DC motor could be obtained as scrap from a broken scooter while the bike could be any that would achieve the appropriate rpm.
An electrolysis unit was designed to operate in a batch system and produce sodium hypochlorite (bleach) solution from salt water. The original salt solution used was 30 g/L, or a 3% by weight solution, and the 12 volt car battery was used to power the system. Electrodes made from several metals were tested, but a titanium cathode and a ruthenium oxide coated anode were selected as the most successful pair due to no significant corrosion over time. Testing proved the ability of the cell to produce enough bleach at a reasonable rate to service the water needed on a given work day. Local pottery could be used to make the electrolysis container. The electrodes used in our system are the only items that could not be obtained from a scrap or local material. While cheaper electrode materials were capable of producing sodium hypochlorite, the reactions time required was longer and there was more corrosion.
Visual Instruction for the General Public
One of the main objectives of the project was to make the results as accessible as possible. This is particularly important given the target audience, rural communities in third world countries. In order to accomplish this objective, Team WaterHOGs developed a set of pictorial instructions that conveys the assembly process of each separate unit, as well as the system as a whole. These instructions are designed so that no minimum level of education or technical background is needed for their execution. The current instructions are available in both English and Hindi (see supplementary materials) and are still in the process of being reduced to minimal language. These instructions are also available on the PI’s website (http://comp.uark.edu/~chesteki/index.php Exit ).
Phase I proved the feasibility of designing and building a working water purification system with minimal cost and limited materials. These types of systems, while simplistic, provide a valuable opportunity for a low cost, sustainable method of water purification in developing nations. By measuring chlorine levels the team was able to determine that the water would be free of microbial contaminants and therefore safe to drink.
The designed system can provide 1,500 gallons of clean water per day to a village using two person manpower during an 8-hour workday. The recommended amount of water usage for drinking, sanitation, bathing, and cooking is about four gallons per person per day so this system would sustain a population of about 375 people (4).
Based on Phase I research, it is expected that this system would be successful should it be implemented during Phase II. Experimentation carried out by the team on the individual system components demonstrated the ability to pump enough water, to filter the water to reduce turbidity and remove particulates, to produce enough sodium hypochlorite (bleach) for microbial disinfection, and to produce enough electricity to power the electrolysis which produces the bleach.
Further testing regarding the performance of the equipment after extended, continuous usage might be necessary. This would be critical in order to develop optimized logistic protocols for both the construction and operation of this system. Therefore, field research centering around the implementation and operation of multiple units in developing nations is highly recommended. Phase II proposes to do this by working with a university in India and implementing the system in key villages in their area.
Supplemental Keywords:Water treatment, water purification, developing countries, electrolysis, filtration, bleach, treadle pump;