Interest Of Membrane Technologies In Africa
By Gilbert Rios
President of “Chaire Unesco Simev” dedicated to membrane science applied to environment.
President of the “European Membrane House”
Membrane technologies are well suited to limit casualties (maternal and child mortality) and financial losses caused by waterborne diseases. On top of superior water quality, their reliability, modularity and their easiness to power with solar photovoltaic energy make them able to play a significant role for the social and economical development of Africa.
For numerous African countries, official reports state that 80% of diseases are waterborne – microorganisms playing a significant role. In Western Africa, 20% of the children die before the age of 5, mainly because of these diseases. Membrane technologies ensure unrivalled consistency of treated water quality.
In rural areas where limited technical capacity may be available, membrane technologies can reliably meet WHO recommendations for microbiological and chemical quality of drinking water.
Access to water, geographical context and cost analysis
More than 60% of the African population live in rural areas. As surface water often is unhealthy, people consume mostly underground water (wells, boreholes, etc.). In semi-arid and desert zones, decision makers may often go for water towers equipped with (solar) pumps to ensure raw water storage and distribution. However these configurations cost more than membrane technologies with no guarantee about water quality.
In Mali, Douentza region, The National Solar Energy Centre has estimated it costs $80,000 to install a water tower (15 m3 storage; solar pump; 60 m deep borehole) for 1,000 inhabitants. This is more expensive than similar capacity membrane technologies ($10,000-30,000) and there is no guarantee that water is drinkable!
Where surface water is available (river, ponds, oasis, etc.) membrane filtration technologies (Micro- and Ultra-filtration) are an alternative to boreholes. When there is no other way to get access to water, nanofiltration/reverse osmosis membrane technologies can ideally complement borehole. The investment pays off every time even when water is brackish or contaminated with toxic chemicals (fluoride, arsenic, nitrates, salt in excess). Otherwise, there is no alternative but shutting down the borehole. Also, the borehole may be drilled closer to the community thus avoiding drilling further away where water quality perhaps is absolute optimal from a hydro-geological point. At the moment this is done with no guarantee of success and little consideration about the (sometime considerable) walking distances to fetch water.
Some boreholes, which were shut down because of water contaminated with chemicals, can be resuscitated thanks to membrane technologies. Membrane technologies effectively and drastically reduce distances to get drinking water. Children and adults can then avoid kilometres of walking to fetch water and instead focus on other activities such as going to school.
Configuration of Modular Membrane Technologies Modular Configuration and Coupling with Renewable Energy
Membrane technologies are modular in essence and perfectly scalable to the wide demographic distribution ranges that exist in Africa. From that perspective, membrane systems can be scaled to meet exactly the needs of the communities. Conventional drinking water treatment plants are not that flexible.
Limitation de la dépendance énergétique – le couplage des technologies membranaires aux systèmes solaires photovoltaïques permet de réduire l’utilisation et la dépendance vis-à-vis des énergies fossiles. C’est aussi le moyen de développer du savoir-faire à l’échelle des villages, et de contenir l’exode rural.
Limiting energy dependency – coupling membrane technologies with solar photovoltaic systems enables reduction in fossil energy use and dependency. It is also a way to develop know-how in the villages and limit rural exodus.
Education – Society and communities are generally very receptive to strategies that help and promote the acquisition of new skills toward development. Membrane technologies and renewable energies meet these expectations as they serve scholarship programme consolidation and university exchanges and generate new jobs (installation, maintenance, equipment repair, etc.)