​Geochemical investigations and scientific-technical support regarding the problem of arsenic contamination in Pabna, Bangladesh

Background/Summary

The Federal Foreign Office states, that globally 663 million people do not have access to clean drinking water (as of 2015). Different factors can endanger drinking water quality. In some countries, drinking water with high arsenic content poses a major threat to public health. Continuous intake has several adverse health effects like increased risk of cancer. Particularly affected by this problem are countries in Asia like Bangladesh, India (West Bengal) and North China (Smedley et al., 2002).

The highly polluted ground water of Bangladesh and West Bengal is internationally recognized a major threat to the affected population (Smedley et al., 2002). To supply germ-free drinking water, groundwater was increasingly exploited as a drinking water resource by the government of Bangladesh and supporting NGOs (Harvey et al., 2002). But utilization of groundwater as drinking water led to the appearance of diseases, which eventually could be attributed to arsenic intake (Smedley et al., 2002).

The research group Hydrochemistry and Hydrogeology at the Institute of Earth Sciences (GEOW) at the University of Heidelberg has profound knowledge about the behavior of arsenic in an aquatic milieu and the geochemical processes related to arsenic sorption and mobility, based on many years of research. Following studies were conducted at five sites near Ullapara, Pabna about 120km WNW of Dhaka. Between September 2015 and April 2017 several near-surface groundwater samples were taken from private wells. Subsequently, they were analyzed in the laboratory of GEOW for arsenic and groundwater composition.

Figure 1 and 2: First sampling campaigns in 2015 and 2016 to get an understanding of the arsenic-mobilizing processes.

Figure 3 and 4: Irrigation wells were also sampled. Field tests revealed, that solved iron is precipitating quickly with addition of oxygen.

Figure 5 and 6: Sediment samples from the topsoil and deeper zones were taken to investigate the mineral composition and the sorbed amount of arsenic.

Samples were taken at five locations in the surroundings of Ullapara, about 120km WNW of Dhaka. Comparable sampling during different seasons revealed, that most of the measured groundwater constituents (also arsenic) fluctuated insignificantly. However, phosphate and organic carbon show distinct seasonal variations with significantly elevated concentrations during rainy season. Both are known to contribute to arsenic release.

The presented projects emerged from a cooperation with the aid organization “AGAPE e.V.” in Heidelberg, which provided financing of travelling and equipment expenses as well as on-site infrastructure. During two field work campaigns two deep well drillings were supervised by GEOW staff and sediment samples were taken. In addition, the geoscientific analysis of the sampled sediments complemented the results of groundwater composition and contributed to the general process understanding. Focus of recent research projects is the exploration of anthropogenic influences on the process of arsenic release. This project is directly continued by the FAARM and AsFreeH2O project collaborations.

Three different filter-types for arsenic removal were developed, based on innovative adsorption technologies. In April 2017, they were installed for test operation at selected locations in Pabna. Follow-up inspections of functionality and potentially optimization for continuous operation are planned for fall 2017.  The filter systems are developed focused on purification capacity, affordability and sustainability by designing a method that includes effective recycling of the used filter materials.

Collaborations with the University of Dhaka and the College of Ullapara have been established within the project and are intended to be intensified in the future. Through cooperation, it is intended to develop a continuous arsenic monitoring system and database.

So far, the outcome of this project has resulted in two Bachelor and three Master theses.