Grantee Research Project Results

Final Report: Drinking Water Purification for U.S.A.-Mexico Border Region

EPA Grant Number: SU833177
Title: Drinking Water Purification for U.S.A.-Mexico Border Region
Investigators: Deng, S. , Torres, Arely , Nunez, Laura , McCool, Ryan
Institution: New Mexico State University - Main Campus
EPA Project Officer: Page, Angela
Phase: I
Project Period: September 30, 2006 through April 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: Pollution Prevention/Sustainable Development , P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources , Sustainable and Healthy Communities

Objective:

One of the most serious problems along the U.S.A.-Mexican border is the lack of access to adequate quality drinking water. The groundwater from wells in Columbus, NM and Palomas, Mexico border region contains significantly high levels of fluoride and arsenic that could potentially cause many serious diseases for the residents, especially young children in this border region. There is an urgent need for purifying the drinking water supplied by the municipals to protect the health of the residents in the border region. Preliminary results from the PI’s research have shown that the sol-gel derived mesoporous alumina-based adsorbent can effectively adsorb both arsenic and fluoride from water. The specific goal of this project is to demonstrate the feasibility of using the mesoporous alumina-based adsorbent for removing both arsenic and fluoride from well waters in Columbus, NM and Palomas, Mexico. Activated alumina-based adsorption systems will be installed in both U.S.A. and Mexico well sites. This technology can be used either in large water treatment plants for municipals and/or the Point-of-Use for individual households. The main technical objective is to remove arsenic and fluoride from groundwater to below 10 μg/L and 4 mg/L, respectively.

Summary/Accomplishments (Outputs/Outcomes):

The major project activities included: sol-gel synthesis and characterization of mesoporous alumina beads; modification of the sol-gel synthesized alumina beads, adsorption equilibrium and kinetic studies of fluoride and arsenic on the sol-gel derived alumina; construction of a packed-bed column with the sol-gel derived alumina adsorbent; and evaluation of the packed-bed column for arsenic removal in adsorption breakthrough experiments. The main findings from this project are:

1. The sol-gel synthesize mesoporous granular alumina adsorbent has the potential for simultaneous removal of arsenic and fluoride from drinking water in the USA-Mexico border region. This adsorbent can be used either in as point-of-entry or point-of-use applications.
2. The sol-gel synthesize mesoporous granular alumina adsorbent has a BET surface area between 240 and 380 m²/g, pore size between 2 and 6 nm, and pore volume of 0.4-0.5 cm³/g.
3. The sol-gel derived alumina showed excellent adsorption capacity for arsenic removal. The dynamic adsorption capacity from the alb breakthrough test is about 16 mg/g for an influent arsenic concentration of 200 μg/L. This data compares very favorably with those of a commercial activate alumina (Alcan AA) and the benchmark adsorbent for arsenic removal (Granular Ferric Hydroxide). The excellent arsenic adsorption property of the sol-gel derived alumina is due to its uniform mesopore size and unique surface properties associated with the sol-gel synthesis process.
4. The sol-gel derived pure alumina has decent adsorption capacity for fluoride. The MnO₂ and CaO modified alumina adsorbents have higher fluoride adsorption capacity due to the introduction of active species. The MnO₂-AA adsorbent is the best candidate for fluoride removal from drinking water at fluoride concentration below 4 ppm, while the CaO-AA adsorbent exhibits higher adsorption capacity at fluoride concentration above 4 ppm.
5. Both adsorption of arsenic and fluoride on the sol-gel derived adsorbent can be described by a Freundlich type of adsorption isotherm equation.
6. The fluoride adsorption kinetics is slightly faster in MnO₂-AA than CaO-AA adsorbent. The estimated effective pore diffusivities of fluoride in the MnO₂-AA and fluoride in the CaO-AA are 4.5x10^-7cm²/s and 4.3x10^-7cm²/s, respectively. These values are about 10 times higher than the effective pore diffusivities of fluoride in the pure sol­gel derived alumina.

Conclusions:

1. It is possible to apply the sol-gel derived alumina for arsenic removal and the MnO₂ modified alumina for fluoride removal for drinking water purification in the USA-Mexico border region.
2. The sol-gel derived alumina adsorbents synthesized in this project are capable of removing arsenic to below 10 ppb and fluoride to below 4 ppm from drinking water and help the USA-Mexico border region to meet the EPA drinking water standard.
3. The proposed process is a lead-lag with the pure alumina as the lead bed for arsenic removal and MnO₂-AA as the adsorbent for fluoride removal.
4. The sol-gel derived alumina adsorbent can last more than 6 months for arsenic removal when the feed water is less than 200 ppb and the service time MnO₂-AA for fluoride removal is to be determined.

Proposed Phase II Objectives and Strategies:

The objectives for the Phase II work is to develop a cost-effective solution from our Phase I results to address the problems of high levels of fluoride and arsenic in the drinking water, and to protect the health of the residents in the U.S.A-Mexico border region. The specific objectives of this research project are:

1. Quantify the modification process for synthesizing MnO₂-AA and CaO-AA for better fluoride adsorption;
2. Study the adsorption equilibrium and kinetics of fluoride and arsenic on MnO₂-AA and CaO-AA adsorbents;
3. Determine the arsenic and fluoride adsorption breakthrough behavior of MnO₂-AA and CaO-AA adsorbents;
4. Search and evaluate natural adsorbents for both fluoride and arsenic removal;
5. Establish adsorption equilibrium and kinetics model to describe the experimental data;
6. Develop a mathematical model to correlate and predict the arsenic and fluoride adsorption breakthrough behavior;
7. Install an adsorption system and test it at the well sites in Columbus, NM and Palomas, Mexico;
8. Estimate the cost for drinking water treatment in large plants and small filters;
9. Train undergraduate and graduate students to solve a real world problem.

Journal Articles on this Report : 1 Displayed | Download in RIS Format

Publications Views

Other project views:	All 3 publications	2 publications in selected types	All 1 journal articles

Publications

Type	Citation	Project	Document Sources
Journal Article	Deng S, Viswanathan V, Candelaria D. Sol-gel derived mesoporous alumina for fluoride and arsenic removal from drinking water. New Mexico Journal of Science 2006;:183-202.	SU833177 (Final)	not available

Supplemental Keywords:

Water Treatment, arsenic, fluoride, engineering, clean technologies, innovative technology, waste reduction, environmental chemistry, analytical, health effects, human health, adsorption, community-based, socio-economic, conservation,, Sustainable Industry/Business, RFA, Scientific Discipline, Geographic Area, Water, Technology for Sustainable Environment, Civil/Environmental Engineering, Sustainable Environment, Drinking Water, US Mexico Boarder, Ecology and Ecosystems, pollution prevention, adsorption processes, arsenic, groundwater, sustainable development, water treatment, drinking water treatment, alumina based adsorbent

Relevant Websites:

http://cheme.nmsu.edu/~sdeng/ Exit