A study of the sources, human health implications and low cost treatment options of iron rich groundwater in the northeastern coastal areas of KwaZulu-Natal, South Africa

Abstract

The groundwater of the northeastern coastal region of KwaZulu-Natal province of South Africa is characterized by high iron content. When the iron rich groundwater is pumped out to the surface, the water forms a precipitate of solid Fe-oxyhydroxide giving the water a cloudy reddish color. This condition is caused by the interaction of Fe2+in the groundwater with atmospheric oxygen. Since this water is unfit for many purposes including domestic use, the local community's water supply is being highly affected. An investigation was undertaken to identify the source of high iron within the Zululand plain groundwater system, the health implications and affordable treatment options in order to make the water suitable for use. The results of the investigation show that the concentration of iron in the groundwater reaches 13mg/L. The measured groundwater EC ranges from 124 to 1060μS/cm, pH ranges from 5 to 8 and redox potential (Eh) ranges from +87 to −89mV indicating both local oxidizing and reducing conditions. The results further show that the groundwater in the area is a fresh water system dominated by a Na–Cl hydrochemical facies indicating strong maritime influences. High iron concentration in water increases growth of unwanted bacteria forming slimy coatings in water pipes and when consumed excessively, it can lead to the build-up of iron in the body resulting into iron stores (high serum ferritin) which may be linked to diseases such as diabetes, heart disease, cancer and kidney problems. High residual content of iron in drinking water is also responsible for the unaesthetic nature of the water such as the metallic taste, discoloration and unpleasant smell of the water. Anaerobic groundwater conditions and the pH range observed during the investigation along with the presence of ferricrete and pyrite rich layers are responsible for the high concentrations of iron (II). An affordable groundwater treatment method based on aeration is recommended in order to safeguard community health, avoid expensive alternative water supply schemes and improve the negative perceptions of communities towards groundwater