Slow and rapid sand filters pdf files

A water treatment system incorporating slow sand filtration can be designed to produce a safe drinking water from even a polluted turbid river water. This energy in a rapid sand filter is usually in the form of head pressurebasically the weight of the water on top of the filter bed. Pathogens are naturally removed in the top layer where a biological film builds up. Pressure filters and diatomaceous filters have been. At present slow sand filters are being used to a limited extent in kenya mainly because emphasis has. Trigger the appropriate controls to supply air and water to the plant. Unless the raw water is relatively free of suspended and.

A free powerpoint ppt presentation displayed as a flash slide show on id. Slow sand filtration water passes slowly downwards ooo ooo ooo oo oo oo o ooo through a bed of fine sand at a steady rate. The schmutzdecke is formed in the first 1020 days of operation and consists of bacteria, fungi, protozoa, rotifera and a range of aquatic insect larvae. The water should not be too turbid, otherwise the filter will get clogged. Pressure filters and diatomaceous filters have been used though very rarely. Slow sand filters work through the formation of a gelatinous layer or biofilm called the hypogeal layer or schmutzdecke in the top few millimetres of the fine sand layer. Slow sand filtration, rapid sand filtration with coagulationflocculation units as essential pretreatment units. Slow sand filter lab effectiveness studies with a mature biolayer have shown 99. Pdf slow and rapid sand filtration methods were tested for their ability to remove triactinomyxon actinospores tams, the waterborne infective stage. The first modern rapid sand filtration plant was designed and built by george w. A slow sand filter ssf is a means of treating water for drinking water. Operate the equipment to filter the water leaving the sedimentation tanks. Compare rapid sand filter and slow sand filter youtube.

One of the oldest methods of water treatment is slow sand filtration ssf also. There are principally two main types of sand filters, rapid sand filters rsf. A welldesigned and properly maintained slow sand filter ssf. With pretreated raw water, a filtrate quality is possible that has less than 1 ntu, 90% removal of coliforms, 50 90% removal of cryptosporidium and giardia cysts, 10% removal of colour, 5% removal of total organic content wedc, 1999 ref. Pdf design and construction of a modified rapid sand. This information is made available by the who in pdf format at. Slow sand filter technology in everyday life cbse grade. Transfer the plant from standby power to the main power supply. There are two main types of sand filters that are used for water treatment. In such a system, the slow sand filter is the most important treatment process but not necessarily the only one. Ppt slow sand filtration powerpoint presentation free. This energy in a rapid sand filter is usually in the form of head pressure basically the weight of the water on top of the filter bed. A who document from 1974 outlining the action, construction, operation and maintenance of slow sand filters.

Pdf rapid and slow sand filtration techniques and their efficacy. The synopsis part of this thesis is available as a pdffile for download from the. This video explains the difference between rapid sand filter and slow sand filter. Roughing filters are used, under certain circumstances, as pretreatment units for the conventional filters. From experience gained in building slow sand filters, some general guidelines for filter design have been established as follows. Design of slow sand filter technology for rural water. Users can maintain flow rate by cleaning the filter through agitating the top level of sand, or by pretreating turbid water before filtration. The institute of catholic bioethics at saint josephs university has recognized this, and has designed a slow sand water filter that is accessible, costeffective, and sustainable. Nitrification biokinetics in rapid sand filters for drinking. Raw water quality requirements incoming, or influent, water should not be too turbid, not exceeding 20 tu and ideally below 10 tu. Slow sand filtration is more cost effective than rapid sand filtration for populations up to 30,000 and possibly considerably higher.