COMPONENTS OF A RAINWATER HARVESTING SYSTEM
CONTINUED...
Filter for large rooftops
When rainwater is harvested in a large rooftop area, the filtering system should accommodate the excess flow. A system is designed with three concentric circular chambers in which the outer chamber is filled with sand, the middle one with coarse aggregate and the inner-most layer with pebbles.This way the area of filtration is increased for sand, in relation to coarse aggregate and pebbles. Rainwater reaches the centre core and is collected in the sump where it is treated with few tablets of chlorine and is made ready for consumption. This system was designed by R Jeyakumar
When rainwater is harvested in a large rooftop area, the filtering system should accommodate the excess flow. A system is designed with three concentric circular chambers in which the outer chamber is filled with sand, the middle one with coarse aggregate and the inner-most layer with pebbles.This way the area of filtration is increased for sand, in relation to coarse aggregate and pebbles. Rainwater reaches the centre core and is collected in the sump where it is treated with few tablets of chlorine and is made ready for consumption. This system was designed by R Jeyakumar
Varun:
S Vishwanath, a Bangalore water harvesting expert, has developed a rainwater filter "VARUN". According to him, from a decently clean roof 'VARUN' can handle a 50 mm per hour intensity rainfall from a 50 square metre roof area. This means the product is relatively standardised. For new house builders we therefore can recommend the number of downpipes they have to optimise on and the number of filters they will need.
S Vishwanath, a Bangalore water harvesting expert, has developed a rainwater filter "VARUN". According to him, from a decently clean roof 'VARUN' can handle a 50 mm per hour intensity rainfall from a 50 square metre roof area. This means the product is relatively standardised. For new house builders we therefore can recommend the number of downpipes they have to optimise on and the number of filters they will need.
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'VARUN' is made from a 90 litre High Density Poly Ethylene (HDPE) drum. The lid is turned over and holes are punched in it. This is the first sieve which keeps out large leaves, twigs etc. Rainwater coming out of the lid sieve then passes through three layers of sponge and a 150 mm thick layer of coarse sand. Presence of sponge makes the cleaning process very easy. Remove the first layer of sponge and soak /clean it in a bucket of water (which you then don't waste but use it for plants). The sand needs no cleaning at all. The basic cost of the filter is about Rs 2250/-
Filters available in the German Market
According to Wessels (1994), concerns over the possible negative health effects of rainwater utilisation led to some opposition. The Federal Office of Health, for example, initially objected to its use for washing clothes, personal hygiene and even for toilet flushing, due to possible risks of infection and allergic reactions. Long-term investigations by the health offices in Hamburg and Bremen, however, have yielded positive results with respect to the use of water for washing purposes and have confirmed that rainwater sources do not present a health risk.
According to Wessels (1994), concerns over the possible negative health effects of rainwater utilisation led to some opposition. The Federal Office of Health, for example, initially objected to its use for washing clothes, personal hygiene and even for toilet flushing, due to possible risks of infection and allergic reactions. Long-term investigations by the health offices in Hamburg and Bremen, however, have yielded positive results with respect to the use of water for washing purposes and have confirmed that rainwater sources do not present a health risk.
(i) Filters developed by WISY
Private companies such as WISY, based in Kefenrod in Germany, and are playing an important role in promoting rainwater use by developing pumps and filter devices to improve water quality. WISY has developed a simple filter system, which can be attached to a standard household downpipe. Under conditions in Germany (assuming a mean annual rainfall of 650mm/year), this can divert and filter 90 per cent of the runoff from a roof area of up to 200 square metre.
Private companies such as WISY, based in Kefenrod in Germany, and are playing an important role in promoting rainwater use by developing pumps and filter devices to improve water quality. WISY has developed a simple filter system, which can be attached to a standard household downpipe. Under conditions in Germany (assuming a mean annual rainfall of 650mm/year), this can divert and filter 90 per cent of the runoff from a roof area of up to 200 square metre.
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(fig a). A filter collector diverts 90 per cent of rainwater to a storage tank through a 0.17 mm stainless steel mesh filter.
 (b) |
(fig b). A larger vortex fine filter can cope with run-off from roof areas of up to 500 square metres.
 (c) |
(fig c). A floating fine suction filter for ensuring that the water pumped from the tank is extracted from the cleanest part of the tank and is free of particulates has also been developed.
For details contact:
WISY (Winkler system)
OT Hitzkirchen, Oberdorfstrasse 26,
D-63699, Kefendrod-Hitzkirchen
Germany; fax:+60-54-912129
Wisyag@t-online.de
(Source: John Gould and Erik Nissen-Petersen, 1999: Rainwater Catchment Systems for Domestic Supply - Design, Construction and Implementation, Intermediate Technology Group)
WISY (Winkler system)
OT Hitzkirchen, Oberdorfstrasse 26,
D-63699, Kefendrod-Hitzkirchen
Germany; fax:+60-54-912129
Wisyag@t-online.de
(Source: John Gould and Erik Nissen-Petersen, 1999: Rainwater Catchment Systems for Domestic Supply - Design, Construction and Implementation, Intermediate Technology Group)
(ii) Filters developed by MALLBETON
Another company, MALLBETON, a manufacturer of concrete tanks and filters, based in Germany, are marketing a tank design which manages any overflows (Konig, 1998). This is done by constructing the top half of a sub-surface tank from a porous concrete ring, which allows water to gradually seep into the ground. While this reduces the volume of water available, it does make householders eligible for waivers on their rainwater drainage fees. These fees are already applied to householders and businesses in about 25 per cent of Germany. The charges that are levied on each square metre of roof area and sealed surroundings can be substantial, such as in Bonn, so waivers often provide significant savings.
(Source: John Gould and Erik Nissen-Petersen, 1999: Rainwater Catchment Systems for Domestic Supply - Design, Construction and Implementation, Intermediate Technology Group)
Another company, MALLBETON, a manufacturer of concrete tanks and filters, based in Germany, are marketing a tank design which manages any overflows (Konig, 1998). This is done by constructing the top half of a sub-surface tank from a porous concrete ring, which allows water to gradually seep into the ground. While this reduces the volume of water available, it does make householders eligible for waivers on their rainwater drainage fees. These fees are already applied to householders and businesses in about 25 per cent of Germany. The charges that are levied on each square metre of roof area and sealed surroundings can be substantial, such as in Bonn, so waivers often provide significant savings.
(Source: John Gould and Erik Nissen-Petersen, 1999: Rainwater Catchment Systems for Domestic Supply - Design, Construction and Implementation, Intermediate Technology Group)
THAT IS ALL ON FILTERS...
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