Rapid sand filter pdf

the Sand Filter via a semi-submerged sedimentation chamber before passing through a sand filter bed prior to discharge. These can be designed to work on-line or off-line. • Source Control Sand Filter (also known as Delaware Sand Filters and Perimeter Sand Filters) Used on some fuel station forecourts or small carparks. These have two chambers. Four basic components of the slow sand filter can be identified: 1. Supernatant, also known as the top water. 2. Filter bed, also known as the bed, media, or sand bed. 3. Under-drainage system. 4. Flow control systems (i.e. regulating valves, weir etc). • Supernatant (Top Water) The storage of water above the bed is called the supernatant. One is slow sand filters and the other is rapid sand filters. The later on is also termed as rapid sand gravity filters or in short form as RSF (rapid sand filter). Innovation (3) PDF (3) quality control (3) Safety (3) Hot Posts . Saw Tooth Roof- Construction - Advantages & Disadvantages; What is a 8 on 12 roof pitch - 8/12 roof pitch 3) Filter run length of capped rapid sand filter increases up to 2 to 2.5 times than that of conventional rapid sand filter. 4) Backwash water requirement for capped rapid sand filter is about 40% that of conventional rapid sand filter i.e. back wash water requirement is reduced by 60%. 6. Future Scope The two most common types of sand filters used in the United States, the Austin Sand Filter (Figure 2.8.3) and the Delaware Perimeter Sand Filter (Figure 2.8.4). The Austin Sand Filter is built at or below grade and is most commonly used for larger drainage areas that have both impervious and pervious surfaces. rapid sand filters is to remove particulate matter in the influent suspension and provide significant pathogen removal. In contrast to slow sand filters, rapid sand filters are operated at a much higher filtration rates (5~10 m/hr) and are frequently used in water More efficient for bacterial removal and less for turbidity and colour removal. Less efficient for bacterial removal and more efficient for turbidity and colour removal. Varies from 3 to 65 mm in size, and 30 to 75 cm in depth. Varies from 3 to 40 mm in size, and 60 to 90 cm in depth. No back washing required. FIG. 1 - BASIC ELEMENTS OF A SLOW SAND FILTER 3 Typical design features of a slow sand filter are as follows: CHARACTERISTICS OF A SLOW SAND FILTER Feature Characteristic Range A B C Depth of water above sand Freeboard above water level 1-1.5m 0.2-0.3 m 0.1-0.2 m/h 25-50 mm 0.3-0.5 m 1-2 m 2-4 mm 0.1-0.3 m 30-40 mm V - filtration velocity in m/h. We can use this equation to compare the required filtration area between slow sand filtration and rapid sand filtration: Assuming a water supply requirement of 24,000 m 3 /day. The area required for slow sand filtration: A= Q/V = (1,000 m 3 /h) / (0.15 m/h) = 6,666 m 2. Area required for rapid sand filtration: In rapid filtration sand is commonly used as the filter medium1but the process is quite different from slow sand filtration. This is so because much coarser sand is used with an effective grain size in the range 0.4-1.2 mm, and the filtration rate is much higher, generally between 5 and 15 m3/m2.h (120-360 m /m2.day). The Rapid Sand Filter (RSF) water treatment equipment differs from the slow sand filter in a variety of ways, the most important of which are the much greater water treatment filtration rate and the ability to clean automatically using backwashing system.RSF does not use biological filtration