COMPONENTS OF A RAINWATER HARVESTING SYSTEM
Continued....
6. Filter
The filter is used to remove suspended pollutants from rainwater collected over roof. A filter unit is a chamber filled with filtering media such as fibre, coarse sand and gravel layers to remove debris and dirt from water before it enters the storage tank or recharges structure. Charcoal can be added for additional filtration.
The filter is used to remove suspended pollutants from rainwater collected over roof. A filter unit is a chamber filled with filtering media such as fibre, coarse sand and gravel layers to remove debris and dirt from water before it enters the storage tank or recharges structure. Charcoal can be added for additional filtration.
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Source: A water harvesting manual for urban areas |
(i) Charcoal water filter
A simple charcoal filter can be made in a drum or an earthen pot. The filter is made of gravel, sand and charcoal, all of which are easily available.
(ii) Sand filters
Sand filters have commonly available sand as filter
media. Sand filters are easy and inexpensive to construct. These filters can be employed for treatment of water to effectively remove turbidity (suspended particles like silt and clay), colour and microorganisms.
A simple charcoal filter can be made in a drum or an earthen pot. The filter is made of gravel, sand and charcoal, all of which are easily available.
(ii) Sand filters
Sand filters have commonly available sand as filter
media. Sand filters are easy and inexpensive to construct. These filters can be employed for treatment of water to effectively remove turbidity (suspended particles like silt and clay), colour and microorganisms.Source: A water harvesting manual for urban areas |
In a simple sand filter that can be constructed domestically, the top layer comprises coarse sand followed by a 5-10 mm layer of gravel followed by another 5-25 cm layer of gravel and boulders.
(ii. a) Dewas filtersMost residents in Dewas, Madhya Pradesh, have wells in their houses. Formerly, all that those wells would do was extract groundwater. But then, the district administration of Dewas initiated a groundwater recharge scheme. The rooftop water was collected and allowed to pass through a filter system called the Dewas filter, designed by Mohan Rao, district collector of Dewas, and engineers of the rural engineering services. The water thus filtered is put into the service tube well.
The filter consists of a polyvinyl chloride (PVC) pipe 140 mm in diameter and 1.2m long. There are three chambers. The first purification chamber has pebbles varying between 2-6 mm, the second chamber has slightly larger pebbles, between 6 and 12 mm and the third chamber has the largest - 12-20 mm pebbles. There is a mesh at the outflow side through which clean water flows out after passing through the three chambers. The cost of this filter unit is Rs 600.
ii. b. Horizontal roughing filter and slow sand filter
The introduction of horizontal roughing filter and slow sand filter (HRF/SSF) to treat surface water has made safe drinking water available in coastal pockets of Orissa. The major components of this filter are described below.1) Filter channel : One square metre in cross-section and eight m in length, laid across the tank embankment, the filter channel consists of three uniform compartments, the first packed with broken bricks, the second with coarse sand, followed by fine sand in the third compartment. The HRF usually consists of filter material like gravel and coarse sand that
2) Sump: A storage provision to collect filtered water from the tank through the filter channel for storage and collection.
The introduction of horizontal roughing filter and slow sand filter (HRF/SSF) to treat surface water has made safe drinking water available in coastal pockets of Orissa. The major components of this filter are described below.1) Filter channel : One square metre in cross-section and eight m in length, laid across the tank embankment, the filter channel consists of three uniform compartments, the first packed with broken bricks, the second with coarse sand, followed by fine sand in the third compartment. The HRF usually consists of filter material like gravel and coarse sand that
2) Sump: A storage provision to collect filtered water from the tank through the filter channel for storage and collection.While HRF acts as a physical filter and is applied to retain solid matter, SSF is primarily a biological filter, used to kill microbes in the water. Both filter types are generally stable, making full use of the natural purification process of harvested surface water and do not require any chemicals.
For more details:
Making Water Everybody's Business
Making Water Everybody's Business
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iii. Rain PC
AcquaSure, a consortium of three specialist Netherlands-based companies, has developed a system for the conversion of rainwater to drinking water in the form of a Rainwater Purification Centre (RainPC).
AcquaSure, a consortium of three specialist Netherlands-based companies, has developed a system for the conversion of rainwater to drinking water in the form of a Rainwater Purification Centre (RainPC).
RainPC is developed by scaling down the multi-staged water treatment method (MST), which involves screening, flocculation sedimentation and filtration and incorporating existing technologies like upward flow fine filtration, absorption and ion exchange. Coming in a small compact 26 kg unit, the RainPC offers an affordable solution by converting rainwater into drinking water.
RainPC is made of ultra violet resistant poly-ethylene housing and cover, stainless steel rods and bolts, a nickel-brass valve and an adapter for maintaining constant volume. Xenotex-A and activated carbon catridges along with ultra membrane filtration or micro-membrane filtration modules incorporated in the RainPC has the capacity to deal with E-coli and the potential of meeting the Dutch as well as World Health Organisations (WHO) water regulation standards. The components can also be transported individually to be assembled at the site. Three product types are available based on their microbial contaminant removal capacity. This technology is ideally suited for virtually any situation and is a blessing particularly for those who have little or no access to regular safe drinking water.
iv. Rainwater harvester
EA Water Pvt Ltd has launched a unique Rainwater Harvester, which filters runoff water from roads, which generally contains oil and grease. This system has been installed in the Gymkhana club, Sector-15, Faridabad, Haryana. Rajit Malohtra, project in charge, of this company explained that the water harvesting system installed at the club has a sand filter, which filters silt from runoff harvested from roof, lawns and parking area. The cost of the filter is around Rs 60,000.
EA Water Pvt Ltd has launched a unique Rainwater Harvester, which filters runoff water from roads, which generally contains oil and grease. This system has been installed in the Gymkhana club, Sector-15, Faridabad, Haryana. Rajit Malohtra, project in charge, of this company explained that the water harvesting system installed at the club has a sand filter, which filters silt from runoff harvested from roof, lawns and parking area. The cost of the filter is around Rs 60,000.
TO BE CONTINUED... J
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