Evaluation of performance of iron removal plants for groundwater treatment in western Kenya

Abstract

Iron is an important constituent in industrial process and drinking water. However, the presence of Iron in excessive concentrations makes the water objectionable for drinking and other industrial applications. Techniques for Iron removal have therefore been developed and further modified over the years to suit various conditions. The study aims at assessing the success to the Iron removal project in provision of improved quality water by use of contact filter in the Kenya-Finland western water supply programme. The study shows that though the technical implementation was carried out successfully, the programme did not adequately train and organise the beneficiary communities to take over the running of the iron removal plants. This very much affected the sustainabilty of these plants. The result of the various investigations shows that, due to its simple technology, contact filter application for iron removal in western Kenya was a good choice for a rural setting. The three models studied vary in capital, operation and maintenance costs. The simplest and the cheapest to install was the Kbayinga and Siginga model, but as explained below these plants had their own water quality and operational limitations. The major drawback was their tedious backwashing method which resulted in continuos loss of filter media. In all cases, the construction materials e.g. sand, cement and gravel, piping material, valves and pumps were available in the project area and elsewhere in Kenya. Iron removal efficiencies for the three models were as follows; Siginga and Kbayinga 96 % Shivanga 94.7 % Lugusi 85.6 %. Despite high iron removal efficiencies at Siginga and Khayinga plants, Iron could not be removed to WHO standard of 0.3 mg!l, due to the high levels of raw water iron concentration of 16.7 mg!l and 14 mg!l respectively. Considering the programme's iron concentration guideline level of 1.0 mg!l, this was a great success. Both Shivanga and Lugusi plants achieved the WHO standard but as indicated by removal efficiencies, this was due to the low concentration of iron in the raw water (0.9 and 0.59 mg!l respectively). The average treated water Iron concentration (mgll) from the four Iron removal plants was as follows; Khayinga Siginya Shivanga Lugusi 0.58 0.70 0.19 0.13 As mentioned earlier on, the project was technically very successful but failed due to poor community mobilisation and training approach.