Tuesday, September 30, 2014

Toilet to Tap: A reality in Bangalore

All of us Facebook users were swept away by the ice bucket challenge created for raising money to patients being treated with amyotrophic lateral sclerosis (ALS) disease. Of all the positive and negative statements about the challenge, one activity has stood out. Matt Damon, (an Actor and founder of water.org) reusing toilet water (https://www.youtube.com/watch?v=DlGhuud-s4w ) to take the challenge while raising awareness about finite resource like water. Owing to the extreme drought like condition in California (Check the link given below) and other parts of the world, a search for reusing wastewater and minimizing dependence on extraction of water is getting priority.

But why go till California when we have our own "toilet to tap" working efficiently!

TZED Homes is 95 flat complex located in Whitefield, Bangalore. Again, like most of the Bangaloreans, this apartment also doesn't get Cauvery water supply. The primary sources of water were borewell and tanker water. The campus is huge in area with 5 acres and large garden space. With the increasing dependence on tanker and borewell water and observing liters of wastewater go down the drain, the need was felt to harvest rain water and waste water for reuse.

As one can imagine the resistance for such concept, many residents had reservations about recycling of waste water for uses other than for garden, carwash and house keeping. There was no precedence of any other apartment complex anywhere in India reusing STP-treated water for uses other than the above. A water committee was formed of passionate individuals to look at these issues.

Srinivasan Sekar, who was a member of the committee, started researching on whether any community around the world was re-using treated waste water for other purposes. He also initiated regular water testing of the treated water, bore well water and tanker water, and found to his (and others’) surprise that STP-treated water consistently came out to be equal or better quality than bore well and tanker water. This discovery led to exploring use of STP treated water for other purposes beyond gardening, car wash and housekeeping purposes.

Several discussions, research into water purification and a series of redundant filters later, TZED Homes designed a system which allows for STP-treated water, after further filtration, to be reused along with bore well water and rain water (tanker water was stopped completely) as input for the RO system, and be re-circulated to residences for general and potable use as well.

Below table is comparative mark up of changes over the years at TZed Homes:

(10 X 7000L) Tanker + (40-60KL) Borewell water to RO unit
40-50KL Borewell/ Rain water and 30KL of STP treated water to RO unit (latter after additional filters)
Daily water need was 90KL RO water with about 30-40KL of RO Reject sent to storm water drain
Daily water need is about 50-60KL of RO water and 20-30KL of RO Reject sent to gardens
40-50KL of STP treated water – about 30-40 KL used for gardens, car wash and housekeeping, rest to storm water drain and/or recharge wells
40-50KL of STP treated water, with about 10KL mixed with RO Reject for gardens, car wash, housekeeping, rest to further filters for RO unit
STP treatment is SBR, with one carbon, one pressurized sand and one Chlorine dozer unit.
After STP treatment, an additional pressurized sand, activated carbon, ozonizer is used before RO unit (which has one more sand, carbon and micron filters)
3 borewells dry (at 250,300ft), one borewell at 650ft yielding intermittent water
All 4 borewells yielding water at 80 ft. Only two used each day alternating.
Water rationing – no water from10AM-4PM; 12 midnight-4AM; lots of water leakages into ground
No water rationing; no water leakages; replaced flushes with timed flushes; aerators on taps; a large swimming pool is included in the water cycle too.

In summary, TZed uses approximately 30-40 KL of total treated wastewater generated in all houses. It is essential to keep in mind that along with the several advantages of reducing pressure on groundwater, the technology needs regular monitoring. STP needs an operator and maintenance cost of approximately 1Lakh per month. In addition, ways should be devised to utilize the amount of sludge generated as a result of wastewater treatment. As mentioned above, TZed being a large campus with big garden space is making manure out of the sludge and reusing it in their garden.

Moreover, it is useful to look at this initiative not only as a technology solving the water problem as technology has always been there but also from a behavioral and psychological perspective as it is the residents who have shown courage and innovation to take up such initiative and took a conscious step towards solving the issue. As Mr. Srinivasan Sekar, a flat owner of TZed and the man behind this change says cheekily, "People have become conscious of what they put into their drainage. Because whatever you put in (paint, chemicals, crackers) is going to come back to you".

Check some other initiatives in California, Singapore, and Namibia for wastewater reuse:


Unknown said...

Very nice article. you should compose this all to a website.

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Anonymous said...

Product of Sri Scientific are below standard. Mr. Anil does not make quality product. His wires for water well measurement are sub standard. I have used them too, and they snapped. They do not also provide the guarantee for the product that they say they do. Never buy from them