The Bangalore Water Supply and Sewerage Board, for the first time in the country, is using at a large scale, the Ultra Filtration (UF) technology for treating sewage for generating recycled water to increase potable water supply.

According to officials, the Ultra Filtration technology is being used in Singapore, where a portion of the recycled water is being used for regular potable purpose by mixing it with the raw water and the remaining portion is being used for manufacturing bottled water.

Even the wastage of water in UF method is also much lesser when compared to the Reverse Osmosis method.

Why UF technology?

According to officials, a comparatively lesser cost involved in the process of recycling by using UF technology though there is another more efficient technology - Reverse Osmosis - which can generate recycled water equivalent to the quality of potable water in terms of the concentration of Total Dissolved Solids (TDS). They point out that the TDS level upto 500 milligram per litre of water is considered as good for drinking and at present the BWSSB is maintaining TDS level between 100 and 200 in various localities.

Slightly higher

However, the TDS level in the recycled water through the UF plant would be around 600-700 mg per litre, which slightly higher than the prescribed level (500 mg/litre).

The TDS level would be reduced when the recycled water is mixed with the rain water stored in the reservoir, the officials informed.

However, the TDS level, at the time of supplying the mixed water from the reservoir after subjecting it to conventional water treatment process, would be about 200 to 300 mg/litre, which would be well within the permissible norms, the officials pointed out.