2019 - 2020 Development of household filters for arsenic removal
Household filters have several advantages over large filter systems, because drinking water for a family of several people is difficult to carry, especially in hot weather and over long distances. Especially since women and children are mainly responsible for transporting water. Thanks to the small filters, families can continue to use their own well, even if it is contaminated with arsenic. Based on the association's decades of experience, several research projects have now been launched to test the technology:
Which filter systems are already available on the market and whether they can also remove arsenic.
What characteristics a filter must have in terms of maintenance, flow rate, handling and price in order to be used by people.
Which filter materials can be used to be sustainable and reusable.
How a deposit system can be established so that used materials can be collected and reprocessed.
The first prototypes are based on filters of the Bengali brand "Drink it". These filters have a multi-layer filter that is designed to remove iron as well as a number of other substances. Iron removal works very well, which means that these filters have a high acceptance. The multi-layer filter cartridge, however, does not bring any noticeable benefits. Removal of arsenic is - as stated by the manufacturer - not possible. Therefore, we have equipped these commercially available filters with a replaceable additional cartridge containing filter materials for the removal of phosphate and arsenic. The test is currently running very successfully for 6 months. Different commercially available filter materials, which can also be recycled, are tested in parallel.
In a first step the filter media of the German manufacturers GEH, HeGo-Biotec and WatchWater were used, who provided us with their products free of charge. We would like to take this opportunity to thank them and in return we have promised the manufacturers that we will send them our results.
2006 - 2013 SONO household filters for villagers
The SONO filters are based on a simple but very efficient operating principle. The high iron content is removed from the groundwater by a two-stage cleaning process. A layer of iron hydroxide and activated carbon also removes arsenic.
The filters must be regenerated with hot water at regular intervals. The service life of the filters is stated as 7 years on average. The problem with this figure is that the service life depends to a very large extent on the concentration of pollutants. This must be checked regularly or the filter must be replaced from time to time.
Major problems were caused by the ochre formation of the filters, i.e. the formation of calcareous iron precipitates which impair the permeability of the filter. The maintenance and repair of the filters was too complicated, so that these filters are now only operated sporadically.