Treatment of arsenic-enriched drinkingwater in Burkina Faso using columnadsorption

Abstract: In the northern part of Burkina Faso, in the Yatenga province, the water in several drinking wells contains arsenic. The arsenic originates from the bedrock and thus affects all those that depend on the deeply drilled tube wells for their daily water needs. Since arsenic is harmful to consume it is important to find a practical way of removing it. Furthermore, since Burkina Faso is one of the world´s poorest countries, the treatment technique has to be economically affordable. This study has evaluated a commercially available granular ferric hydroxide (GFH®) product as an arsenic adsorbent material when purifying arsenic-enriched water in Burkina Faso. The treatment method was based on a technique where arsenic-enriched water was pumped through a column packed with the adsorbent material. Previous investigations of this material and method have been performed on the water from the northern part of Burkina Faso; water from the northern part of the country was also used this time but the experiment was executed at a larger scale. With a flow rate of ten litres per hour through the column, the result showed an adsorption capacity of 370 micrograms arsenic per cubic centimetre adsorbent. The conclusion was that the GFH® worked well as an arsenic adsorbent material. In the future, it can probably be used in full scale systems but before that, more research and development have to be done. Some practical problems such as how to construct the set up, how to change the adsorbent material, what to do with the used adsorbent material, and how often to change it also need to be solved. Tests with lateritic soil from Burkina Faso as an adsorbent material were also executed. The advantages of using this lateritic soil instead of GFH® would be that it is less expensive and domestically available. With a flow rate of 0.85 litres per hour the results of these tests showed an adsorption capacity of at least 5.2 microgram arsenic per cubic centimetre material. Hence, the conclusion was that the natural lateritic soil had some potential to remove arsenic, but that the removal capacity was too low for natural lateritic soil to practically work as adsorbent material when using the column method.