Grantee Research Project Results

Final Report: Providing Safe Water to Rural Nepal: A Novel Water Filtration System

EPA Grant Number: SU833180
Title: Providing Safe Water to Rural Nepal: A Novel Water Filtration System
Investigators: Kilduff, James E. , Gerbini, Alessandro , Deede, Ben , Lennox, Erin , Martin, Heather , Desai, Hemal , Arrighi, Julie , Sawicz, Keith , Raju, Reenu , Komisar, Simeon , Jovic, Srdjan , Gupta, Swati , Carley, Victoria
Institution: Rensselaer Polytechnic Institute
EPA Project Officer: Page, Angela
Phase: I
Project Period: September 30, 2006 through May 30, 2007
Project Amount: $10,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2006) RFA Text |  Recipients Lists
Research Category: P3 Challenge Area - Safe and Sustainable Water Resources , Pollution Prevention/Sustainable Development , P3 Awards , Sustainable and Healthy Communities

Objective:

The objective of this project was to research and develop a sustainable water filtration system that could be built in Nepal using basic, locally available building materials and tools. This system is composed of three separate parts – a flocculation and sedimentation tank, a modular filter, and a storage tank within an external support structure. The flocculation and sedimentation tank is used to remove suspended particles, and possibly some arsenic, from the water by addition of a coagulant. The filter drawers are used to hold sand and activated carbon in order to remove remaining particles and arsenic from the water. The storage tank is used to store water after it has been treated, so that it is readily available for distribution.

Treatment of turbid and contaminated water in developing countries is becoming of increasing importance due to environmental, economic, and health factors. Moringa oleifera (M. oleifera) is a natural plant coagulant that has the potential for water treatment and arsenic removal. It is a sustainable alternative to chemicals like ferric chloride and alum that may have negative environmental, economic, and health effects. The coagulation mechanism of dry M. oleifera seeds was studied and compared to ferric chloride. M. oleifera seeds may also be capable of removing arsenic from contaminated water, and thus the effect of arsenic removal was compared with ferric chloride.

Sand and charcoal are used as an additional step in particle removal. Studies have shown that impregnation of iron is possible at ambient temperatures using simple iron reagents (aqueous solutions of ferric chloride) and readily obtainable oxidants (air and/or chlorine). The iron-coated charcoal is used to remove arsenic from the water, because arsenic forms strong complexes with iron that is bound to the charcoal surface.

Summary/Accomplishments (Outputs/Outcomes):

A preliminary design prototype was constructed from wood as this was found to work better than concrete because it was easier to manipulate and change as the design evolved. Once a final prototype is determined a mold will be constructed to mass-produce the filter out of concrete, as concrete is readily available in Nepal.

The active agents in the coagulation with M. oleifera seeds are water-soluble materials. The coagulation properties of M. oleifera seeds are similar to those of FeCl₃. A 1% by weight solution at a dose of 5 mL/L of M. oleifera extract resulted in over 50% turbidity removal. A minimum in residual turbidity was observed, with increasing turbidity at high dosages. Filtering the solutions after sedimentation resulted in significantly reduced turbidity. Filtered M. oleifera seed solution also had better coagulation properties than unfiltered M. oleifera seed solution. M. oleifera did not significantly change the pH or conductivity of the water, as compared to a high concentration of FeCl₃ that resulted in significantly lower pH and higher conductivity. M. oleifera seeds are also capable of removing arsenate in solution during the coagulation and flocculation process. Results show that at both a 1 mL/L concentration and a 5 mL/L concentration, 93.68% ± 0.25% of the arsenate is removed from solution. This is much higher than the removal of arsenate by FeCl₃, which is best at a 5 mL/L dose that resulted in 76.81 ± 0.06% arsenate removal.

It was found that 14g of a non-heat-treated version of a commercially activated charcoal, used as a model to represent wood char, removed arsenate to 60% of the original arsenate concentration of 20mg/L This was far better than the heat-treated charcoal that did not show any removal of arsenate. The effectiveness of repeated filtration was also tested. The first few filtrations of 20mL of the arsenate water through 14g of charcoal yielded very yellow, aesthetically displeasing water. However, the color quickly dissipated after multiple runs. Thirteen filtrations of 20 mL of water containing 20 mg/L of arsenate, at a flow rate of 0.91 mL/second, resulted in 64.6% ± 7.9% arsenate removal.

Conclusions:

Construction and fabrication of the filter is relatively simple, and is sufficiently flexible to allow for variations in the design. The filtration drawers are designed for easy removal and replacement of filtration media. Two waterspouts have been included in the storage tank to comply with any cultural caste disputes that may occur.

M. oleifera seeds are a viable, sustainable alternative to chemicals typically used as a coagulant. They are inexpensive, biodegradable, and easy to obtain. Also, because they are a natural material, they are less likely than chemical coagulants to have negative health and environmental effects. Additional experiments need to be conducted involving varying doses and concentrations of M. oleifera to determine the optimum values necessary to remove particulates and turbidity from groundwater in Nepal. Additional testing of arsenate removal using M. oleifera seed solutions should be conducted. A process for filtering the seed solutions should also be developed.

Iron-coated charcoal has been proven an effective means of removing arsenic by over 50% at high concentrations (i.e. 20 mg/L). While this removal can legitimately be extrapolated to lower initial ranges of arsenate concentration, it is still necessary to test in the part per billion range, similar to that found in groundwater in Nepal. Charcoal was effectively coated with iron in a laboratory setting; however, this process should be further refined for the ease of use in a Nepal village.

Proposed Phase II Objectives and Strategies:
At this time, the Rensselaer Polytechnic Institute Team does not feel ready to apply for additional funding. There are still many issues from the Phase I proposal that need to be addressed and looked into before distribution of the filter can be realistically examined. In addition, approximately half of the student team will be graduating this May. There is insufficient student interest in continuing the project to be able to confidently guarantee that if awarded the grant, the research would be able to continue forward at an acceptable rate. Once the remaining issues have been examined in more depth, the Phase I grant will be applied for again to start mass production of the filter and to determine the logistical details of distribution in Nepal.

Supplemental Keywords:

adsorption, drinking water, groundwater, human health, toxics, metals, sustainable development, treatment, environmental chemistry, engineering, Southeast Asia, POLLUTANTS/TOXICS, Geographic Area, TREATMENT/CONTROL, Sustainable Industry/Business, Scientific Discipline, RFA, Technology for Sustainable Environment, Sustainable Environment, Technology, Chemicals, Environmental Engineering, International, heavy metals, clean technologies, arsenic removal, sustainable development, drinking water, Nepal, charcoal filtration, pathogen removal,, RFA, Scientific Discipline, Geographic Area, Water, TREATMENT/CONTROL, POLLUTANTS/TOXICS, Sustainable Industry/Business, Sustainable Environment, Technology, Chemicals, Technology for Sustainable Environment, International, Drinking Water, Environmental Engineering, sustainable development, well water, clean technologies, Nepal, filtration, charcoal filtration, pathogen removal, drinking water monitoring, arsenic removal, water quality, pollution prevention, drinking water contaminants, drinking water treatment, water treatment, arsenic