Development of a low cost iron removal plant for hand tubewell

Abstract

The rural water supply in Bangladesh is based on hand pump tubewells installed to collect water from shallow aquifers. But the use of tubewell water for domestic purposes is declining due to the presence of high concentration of iron in the ground water of some rural areas. In these iron problem areas people are inclined to use water from unprotected sources which indirectly affect the health of the rural community. So to make an effort to polve these problems, several iron problem areas were surveyed and some households were interviewed about their opinions regarding water quality and the reasons for non-usage of tubewell water in iron problem areas. The rural people of those areas also told about different water sources which they use for various domestic purposes. It was observed that the main reasons for the non-usage of tubewell water in an iron problem area were aesthetics and staining clothes and utensils. In a locality where iron concentration of tubewell water was above 20.0 mgtl, an iron removal plant with a gravity flow aerator, a coarse media flocculator, a plain sedimentation tank and a coarse media filtration chamber was constructed and its performance was observed. The iron removal efficiency was good enough, but the yield as well as filter run was neither satisfactory nor acceptable to the rural people. Then the design of the plant was modified, e.g. tubesettlers were placed in the sedimentation chamber instead of a plain sedimentation chamber, an additional narrow plain sedimentation chamber was built after the filtration chamber. The performance of the modified plant was found quite satisfactory to the rural people both in removing iron from water and increasing yield as well as filter run. In this plant the iron removal efficiency was found to be 99.3%, the yield was 14.4 litres/min which was about 75.6% higher than the yield of the previous plant. Maintenance problem, the most important problem of all the Iron Removal Plants constructed so far, was also removed by increasing the filter run to 22 days--- an increase of about 55.0% compared to the filter run of the previous plant. The cleaning procedure which is very simple and easy to do is also accepted to the consumers. After the construction of the plant, the households using the effluent water were also interviewed and it was observed that the water quality, plant yield and cleaning frequency are acceptable to the people.