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Garnet symbol (Global Applied Research Network)
Iron and manganese removal

The aim of this network is to promote exchange of ideas, experience and research findings between individuals and organisations interested in the removal of iron and manganese from groundwater, with particular reference to technologies and practices relevant to less developed countries.

Objectives:

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to ensure that the research community is aware of the needs of practitioners faced with problems of groundwater contaminated with iron and manganese;

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to ensure that practitioners learn from each other (learning lessons from the field);

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to ensure that practitioners have access to the latest applied research in this field; and

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to establish the state of the art in iron and manganese removal and to ensure that future research starts from that point and that we avoid unnecessary duplication and replication of effort.


Types of information to be made available:

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contact details of interested individuals and organisations;

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an I&M removal bibliography;

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case studies; and

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summaries of research project findings.


Research Findings

Thesis: Technology choice for sustainable development: research into an iron removal plant for Uganda - Sarah Hindle

Technical Abstract

As a drinking water source groundwater is often considered as better than surface water because it does not contain harmful pathogens and generally does not need treatment. However in many locations it contains iron, either from geological formations or from iron pump components. Iron is not harmful to health, but causes people to reject the water, mainly because it tastes bad and stains clothes, containers and skin. In rural areas in developing countries where groundwater is extracted by handpumps, rejection of this borehole water causes people to drink contaminated surface water and this can result in disease and death, especially for young children. Much research has been done to find a sustainable iron removal plant (IRP), but this has proved very difficult because of the maintenance required, which is arduous although not technically complicated.

Uganda has areas of very high iron content and the Government of Uganda plans to increase the use of groundwater throughout the country, therefore it is important to investigate the possibility of a sustainable method of iron removal.

My research fulfilled three objectives:

1. Evaluating the Performance of the Silsoe Filter in the Field.

A simple IRP that focussed on the action of bacteria in a filter to remove iron had been developed at Silsoe (Cranfield University – UK), but not tested extensively in the field. In 2000 three filters of this type were constructed in Western Uganda and monitored for a few months, but had not been visited since. I travelled to Uganda to evaluate the performance of these filters, to uncover any problems that had arisen during the two years of operation and to investigate ways to improve their performance. The tests showed that the filters were not performing as well as previous research had indicated. Iron concentrations of 40.5mg/l were reduced to 15.5mg/l which was not acceptable for drinking, but water of 14.1mg/l iron reduced to 6.0mg/l was drunk by villagers who were patient enough to join the queue at the borehole caused by the slow flow-rate through the filter. The filters were maintained by paid staff, who found cleaning them hard work and only cleaned the filters when the water quality was bad enough to cause complaints from the villagers. Tests were done to investigate the cause of the poor performance of the filters and to find out how to improve it. Four areas were studied and conclusions arrived at:

· The media size is not critical, but if the grains are too fine (less than about 1mm diameter) the filter clogs very quickly.

· The position of the Rest Water Level, either above or below the sand level, does not seem to make a big difference to the performance.

· Aeration is very important, especially with high iron concentrations.

· Installing an up-flow roughing filter before the sand filter increases iron removal to an acceptable level, even with high initial concentrations of 42mg/l.

2. Assessing the sustainability of IRP Technology for Rural Uganda

This part of the report draws on my fieldwork and also on an extensive literature review covering the experiences of engineers in many parts of the world who have developed their own designs of IRP. These were built in areas where the iron concentrations are less than in many parts of Uganda, but still encountered many problems. The reasons for the failure of these IRPs are studied and the most important considerations in IRP design are examined in detail: efficiency of iron removal, construction, operation (especially the challenge of slow flow-rate through the filter), maintenance (in the context of the institutional situation in Uganda) and hygiene. Maintenance is the most critical issue and IRPs will only be sustainable if they are chosen by a community from a variety of water supply options. The community must be aware of the maintenance requirements and of their own responsibilities.

If a borehole yields water with high iron content the first concern is to check that the iron is from a geological source, not from iron pump components. In India vast numbers of IRPs have been built, but now this programme has been abandoned in favour of replacing Galvanised Iron pump parts with PVC and stainless steel. This has been effective in reducing the iron concentrations in borehole water in many cases and this course of action seems to be the most sustainable for Uganda, along with that of looking at alternative water sources such as rain water.

3. Suggesting an IRP design for Uganda

Despite these obstacles a design has been suggested, based on current IRPs and a literature review of the treatment processes involved in removing iron. The design contains three chambers and is modular. While the first chamber is a sedimentation chamber and the third a slow sand filter, the middle chamber can either be a second sedimentation chamber (for lower iron concentrations) or an up-flow roughing filter. This design takes into account the fact that different water conditions and user preferences mean that a generic solution to the iron removal problem is not possible, but also seeks to minimise maintenance requirements. The design is simple enough for villagers to construct under the guidance of one literate artisan and construction details are not specified.

For a summary of the thesis, click here.

Report: Iron removal from groundwater in Rakai District, Uganda: a minor field study - Andersson, Hanna and Jenny Johansson

To see the report, click here.

For further information, contact:
Sean Tyrrel,
Lecturer in Microbiology,
Institute of Water and Environment,
Cranfield University,
Silsoe,
Bedford,
MK45 4DT,
United Kingdom.

Tel: +44 1525 863293
Fax: +44 1525 863300
Email: s.tyrrel@cranfield.ac.uk


See also...


Silsoe's Biological Removal of Iron from Handpump water supplies

Fundamentals of media filtration for iron and manganese removal

Updated 17/07/03

Maintained by f.o.odhiambo@lboro.ac.uk and j.fisher1@lboro.ac.uk

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