Basically, after a mesh filter removes larger debris, a media filter such as a rapid sand filter will further filter out organic material such as algae and bacterial sludge as well as fine sediments such as silt and clay (Bartok, 2009). However, this treatment requires a large area. It may be different from the other media filter which is a slow sand filter. (Figure 1.5) Since the slow sand filtration used much finer sand than the rapid sand filter where the sand used is larger than 1 mm