Water Filtration

Filtration is the process of separating the liquid from the particles contained in it by passing the liquid through a permeable material. According to Amrih (2005), the simplest and easiest filtering technique is to use a clean cotton cloth, which can clean water from dirt and small organisms present in turbid water, but the results depend on the thickness and density of the fabric. The second technique is better, using cotton, which also depends on the thickness and density of the cotton. The third technique is aeration, which is injecting oxygen into the water to reduce or eliminate carbon dioxide, hydrogen sulfide, and methane that affect the taste and odor of water. Besides, mineral particles dissolved in water such as iron and manganese will be oxidized and will quickly form a deposition layer which can later be removed through the process of sedimentation or filtration. The fourth technique is a slow sand filter (SPL), which consists of a layer of sand on the top and gravel on the bottom. Clean water is obtained by filtering raw water through a layer of sand first and then passing through a layer of gravel. The fifth technique is a quicksand filter, the same as a slow sand filter, but the direction of water filtering is reversed, ie from the bottom to the top (upflow). The 6th technique is the gravity-fed filtering system which is a combination of SPC and SPL. Clean water is produced in two stages, first with slow then with slow sand filter. Several slow sand filters are used to overcome the quantity of water discharge from the quicksand filter. The 7th technique is a charcoal filter, which is a sand filter added with a single layer of charcoal, which is very effective in removing odors and flavors that exist in raw water. Charcoal is made from wood or coconut shells, or preferably activated charcoal. Some commercially activated charcoal filters are available in the market. A simple/traditional water filter is a modification of a charcoal sand filter and a slow sand filter and uses layers of sand, gravel, stone, charcoal, and fibers. Another technique uses ceramic filters that can be stored for long periods so that they can be prepared and used for emergencies. A silver mixture that functions as a disinfectant can be added to the filter. The filter can be brushed to clean it (Freeman et al., 2012). Another form of filter made of rock, shaped like a jug/mortar, commonly used by people in several villages in Bali. Water, from dug wells or rice field irrigation channels, is placed in a container in which stone mortars are placed and the water will be filtered into mortars through rock pores, but the filtering speed is relatively low when compared to slow sand filter or quicksand filter. Nowadays there are many other modern filtering techniques with varying applications such as reverse osmosis, microfiltration, and ultrafiltration using various membrane materials.