Arsenic Removal for Drinking Water Treatment in Nicaraguan Rural Communities

Research objectives
The aim of this research is to enhance fundamental understanding of As(III) oxidation pathways on metallic surfaces and As(III) and As(V) adsorption pathways on corroding metallic surfaces. At the same time, the effect of these metallic surfaces on E.coli survival during drinking water treatment and storage will be investigated.

These finding will be used to develop an effective and affordable treatment system for the removal of arsenic in groundwater for rural communities and small towns in Nicaragua, while also ensuring microbial safe drinking water.

Project outline
Introduction
Water ingestion with high concentrations of Arsenic (As), leads to greater cancer risk than any other common water contaminant. (Smith AH et al, 2007). According to a study published by Barragne-Bigot in 2004, in Nicaragua approximately 55,700 people were ingesting water contaminated by arsenic (As).   Most of those people lived in scattered small rural communities or were semi-concentrated in municipal and small towns. The number of people who currently are ingesting water with arsenic in rural Nicaraguan communities is unknown.  A clean and safe drinking water supply is a basic human right that is being denied to poor and rural communities affected by arsenic poisoning and a limited access to water.

Figure 1 Municipalities of Nicaragua with water sources where arsenic concentration exceeds the national regulatory limit of arsenic in drinking water (10μg As/ l) as of  2011.  (Bundschuh J, et al, 2011)

Approach
In the first PhD year, the aim is to gather all the available information related to arsenic in Nicaragua. This information is scattered in different institutions (e.g the Nicaraguan Institute of Aqueducts and Sewers, Ministry of Health etc). The second step consists in locating arsenic-affected communities and determine As concentration, As speciation, As source, as well as measuring the chemical and physical composition of water. This baseline study will allow for a smart design of experimental procedures for the laboratory experiments to be executed in the Netherlands (starting mid 2015).

Scientific relevance
Metallic surfaces have the potential to improve drinking water quality because they generate Reactive Oxygen Species (ROS). Reactive Oxygen Species in water, can inactivate bacteria (e.g Escherichia coli ,  an indicator organism for faecal contamination ) and catalyse oxidation of As(III), in additioncorroding zero-valent metallic surfaces can adsorb arsenic .However, the mechanisms of metallic surface induced ROS formation in water are unclear, limiting their safe application in water solutions around the world.  

Social relevance
In Nicaragua the knowledge of arsenic removal systems comes from the research performed by local universities or NGOs working with water and sanitation. Despite the great efforts of the universities and NGOs, there is still very little hands-on experience with arsenic removal. For this reason, it can be said that this first and long-term study is aimed at evaluating, adapting and developing arsenic removal systems so they can be used at a local level.

By combining scientific inquiry with a concern for social welfare, this study will be useful as a document of reference in universities, research centers on water resources, NGOs and institutions working on water supply projects or managing this service at a private or public level.

The Director of UNICEF in Nicaragua, Philippe Barragne-Bigot, who a few years ago led several research related to arsenic problems in rural communities in Nicaragua, recently defined arsenic as a forgotten deadly threat. Therefore, this study will be of great help to understand the real reach of the arsenic problem in Nicaragua.

Literature

  • Altamirano  Espinoza M. Bundschuh J. Natural arsenic groundwater contamination of the sedimentary aquifers of the southwestern Sébaco valley, Nicaragua. In: Bundschuh J. Armienta MA Birkle P. Battacharya P, Matschullat J, Mukherjee AB, editors, Natural arsenic in groundwater of Latin America, Leiden, The Netherlands : CRC Press/Balkema Publisher : 2009. P 109- 2002
  • Barragne P (2004). Contribución al estudio de cinco zonas contaminadas naturalmente por arsénico en Nicaragua. UNICEF, Managua, Nicaragua.