Development of low cost easy to clean filtration technology

Résumé

Filtration of water is an important unit process for treating surface water sources for potable water treatment applications.  The use of both slow sand filter as well as rapid sand filter has to take into account the suspended solids load of the raw water which in tropical climate can be very high during the rainy seasons. An appropriate treatment alternative that can handle high suspended solids load while being easy to clean would be desirable filtration alternative. This research paper is a result of an experimental study of a filtration technique that employed a two stage filtration with floating plastic media with coarser and finer media sizes respectively. The media are packed (pressed) during filtration and later during backwashing the packing is released to allow the media to self-float.  The treatment capability with wide range of raw water turbidities has been tested and the system has capability to treated water to required low water turbidities needed for subsequent disinfection. Cleaning is made easier by the self-floating characteristics of the media. In addition it was possible to clean the filter using raw water rather than filtered water. High rate of filtration is achieved through a combination of locally available coagulant of the seeds of Moringa tree while simple flocculation using grave column flcooculator has been employed.