Hydraulic ram pumps and Sling Pumps

GARNET - Global Applied Research Network - Iron and manganese removalA simple IRP that focussed on the action of bacteria in a filter to remove ironhad been developed at Silsoe (Cranfield University – UK), but not testedextensively in the field. In 2000 three filters of this type were constructed inWestern Uganda and monitored for a few months, but had not been visitedsince. I travelled to Uganda to evaluate the performance of these filters, touncover any problems that had arisen during the two years of operation andto investigate ways to improve their performance. The tests showed that thefilters were not performing as well as previous research had indicated. Ironconcentrations of 40.5mg/l were reduced to 15.5mg/l which was notacceptable for drinking, but water of 14.1mg/l iron reduced to 6.0mg/l wasdrunk by villagers who were patient enough to join the queue at theborehole caused by the slow flow-rate through the filter. The filters weremaintained by paid staff, who found cleaning them hard work and onlycleaned the filters when the water quality was bad enough to causecomplaints from the villagers. Tests were done to investigate the cause ofthe poor performance of the filters and to find out how to improve it. Fourareas were studied and conclusions arrived at:· The media size is not critical, but if the grains are too fine (less than about1mm 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 ironremoval to an acceptable level, even with high initial concentrations of42mg/l.2. Assessing the sustainability of IRP Technology for Rural UgandaThis part of the report draws on my fieldwork and also on an extensiveliterature review covering the experiences of engineers in many parts of theworld who have developed their own designs of IRP. These were built inareas where the iron concentrations are less than in many parts of Uganda,but still encountered many problems. The reasons for the failure of theseIRPs are studied and the most important considerations in IRP design areexamined 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 ifhttp://www.lboro.ac.uk/departments/cv/wedc/garnet/tncironm.html (3 of 5) [1/13/2005 12:49:30 PM]