India File

Waste water everywhere? Recycle it

A Srinivas | Updated on August 02, 2018 Published on July 16, 2018

While the use of sewage for potable purposes is still to pick up in a big way globally, its use for non-potable ends worldwide is far more common   -  Lilkin

Cities need to shift to waste recycling to preserve future resources, for which the finance and technology constraints need to be sorted out. A Srinivas reports

Around 11 pm on May 31, Shimla High Court’s acting Chief Justice Sanjay Karol gathered forces, summoning the city’s Deputy Commissioner Amit Kashyap and Municipal Commissioner Rohit Jamwal for what turned out to be an all-night patrol around the picturesque Ridge, the Mall, Sanjauli, Chaura Maidan and four water control rooms dotting the hill capital of Himachal Pradesh.

The Chief Justice had decided to take matters into his own hands. He walked around, asking the still-remaining tourists about their experiences and drove with the city’s top bureaucrats to all the four nodal water control rooms to sit with the men who manned the water supply lines.

Shimla, a tiny city, needs at least 48 MLD (million litres/day) of potable water and the availability dropped to just about 20 MLD owing to drying up of the different water sources.

In Nahan, the headquarters of Sirmaur district which itself was reeling under water shortage, majority of the 20-odd private water tanker suppliers refused to comply. “I have difficulty catering to the demand here. Why should I travel 130 km to Shimla, arrange for my stay, food and other logistics and ferry water when I have enough business in my home town?” said Shyam Saini who runs a private tanker business in Nahan.

This is a sad commentary for a State which gets an enormous volume of water from the catchment areas of Satluj, Beas, Ravi and Chenab rivers, besides the estimated 800 glaciers.

If this is the state of affairs in Himachal Pradesh, the situation in regions with larger urban populations, inadequate waste water treatment facilities (Himachal scores better in recycling than most States, according to the NITI Aayog), low groundwater tables and rising water contamination can well be imagined. The NITI Aayog’s Composite Water Management Index report paints a dire picture for urban India (see factbox).

 

 

 

There are three ways to overcome this crisis in the cities: reduce wastage, store rainwater and recycle used water. The potential of water recycling to meet non-potable needs such as for gardening, toilet and laundry, which accounts for at least 60 per cent of domestic water, use is huge. In fact, Brisbane, Singapore, Windhoek (Namibia) and California’s Orange County are recycling waste water for drinking. While the use of sewage for potable purposes is still to pick up in a big way globally, its use for non-potable ends worldwide is far more common (see factbox).

 

 

Recycling in Bengaluru

In the water conservation sector, there is an ongoing debate between rainwater harvesting enthusiasts and those who vouch for the potential of water recycling to meet domestic needs. Says MN Thippeswamy, Retired Chief Engineer-Super Time, Bangalore Water Supply and Sewerage Board: “Waste water recycling can meet more than 20 per cent of the city’s daily needs.” Besides, it generates positive effects such as cleaner lakes, rivers and groundwater. (The pie-chart on ‘Strategy for Sustainable Water Supply to Bengaluru’ estimates the potential of waste water recycling at 10 per cent and rainwater harvesting at 20 per cent.)

 

Out of 1,600 million litres of day (MLD) of sewage that the city generates (about 80 per cent of water consumed is wastage, as a general rule), only about 600 MLD is treated by about 25 plants set up by the BWSSB as well as by apartment complexes, the total installed capacity being about 1,500 MLD. Of this 600 MLD, no more than a tenth is reused. For instance, the Yelahanka tertiary treatment plant supplies water for non-potable uses to the Kempegowda International Airport and a few other institutions. Most treatment plants treat water till the secondary stage, making it fit for discharging into the lakes or for certain industrial uses such as cooling.

Observes Anant S Kodavasal, Director, Ecotech, a company that sets up sewage treatment plants and manages O&M for apartment complexes and industrial plants in Bengaluru and other places: “There are at least 2,500 STPs in apartment complexes in Bengaluru which can potentially treat 350 MLD of sewage. This works out to 20 per cent of total sewage generated. However, 80 per cent of these plants as well as the ones run by BWSSB are defunct.”

Interestingly, Bengaluru, according to State government sources, is planning to process sewage for drinking purposes. A project that is likely to get Central funds will treat sewage of the Vrishabhavathi river flowing in the south-western side till the tertiary stage and put that water into the Arkavathi river in the south-eastern side which, in turn, will be treated for drinking.

“This is like the Singapore model, where water is recycled and indirectly sent back to households, so that prejudices are taken care of,” Tippeswamy explains.

In Delhi, the situation is better on paper. A consumption of 3,420 MLD leads to waste water of over 2,600 MLD, of which 1,600 MLD is treated and 338 MLD is reused. However, that does not really explain why the Yamuna is such a dirty river. The Delhi government concedes that the low flow of sewage in STPs, and trunk and peripheral sewer lines still to be connected to them has impeded the effectiveness of sewage treatment.

The waste water treatment scenario is much worse in Mumbai. According to officials in the Municipal Corporation of Greater Mumbai, out of 3,750 MLD supply, 2,300-2,400 MLD goes into the sea, almost untreated. MCGM officials claim that its seven STPs are working. Tenders have been placed for six sewage treatment plants, which will treat 2,600-2,700 MLD. Construction is expected to commence in October.

The treated water will be used for non-potable uses such as toilets and washing of trains. An investment of ₹6,000 crore will be needed to convert grey water into potable water, officials say.

 

 

Ineffective STPs

There is no consensus on why STPs are ineffective. Kodavasal says that the wrong model of STPs is often to blame, arguing that the conventional aeration reactor is an underrated option. The sequential batch reactor (SBR), he says, is not effective in apartment complexes. BWSSB officials argue that defunct, leaky pipelines are the bigger problem, for which funds are wanting.

However, Madan Iyengar, Managing Director, Ozo Nano Sciences, observes that the existing technologies, be it conventional aeration or SBR or other membrane-bed reactors, are not adequate for dealing with a combination of chemical and municipal sewage. “They leave an odour, of hydogen sulphide,” he says. Claiming that he uses nanotechnology effectively to clear the water of oil and other pollutants in the petrochemicals and textiles industries, he says that no residue should be left behind. Tippeswamy argues that reverse osmosis membranes can filter out the finest of microbes.

Economics of water

The question, then, is of cost and access to technology. Pawan Sachdeva, a Singapore-based consultant, says that water should not be underpriced as that hurts the poor. “By not recovering its costs, the utility is unable to lay pipelines to serve the poor, and they end up buying expensive water with no assurance of quality,” he says. Says rainwater harvesting advocate S Vishwanath: “Waste water recycling will not be a reality, say, in the context of Bellandur lake in Bengaluru, when a household cannot pay a bill of ₹1,600 per month for a consumption of 20,000 litres a month, which will cover the cost of carrying and treating water.”

Citing the lack of data on water use as a problem, Sachdeva suggests a way: using a proxy such as electricity consumption. “In Delhi, a household that pays an electricity bill of ₹10,000 a month may end up paying a few hundred rupees for water. This is ridiculous. With Aadhaar, we can sort out these issues,” he says.

The role of the government to provide subsidy and efficient delivery of water services by the water utility should be separated, he argues. The latter should get paid by the government if the pricing of water is lower than what is justified as per the cost of capital, Sachdeva adds.

The PPP approach being tried out in the Namami Gange PPP is another option. Says Neeraj Gupta, IFC Team Leader for Namami Gange: “We have been engaged in designing hybrid annuity structure for STPs as a transaction advisor. The model was tried out for the first time in India.”

Gupta explains: “Under this, the government pays 40 per cent of the project cost linked to construction milestones. The remaining 60 per cent is paid over 15 years as annuities to the private concessionaire along with O&M expense.” With innovative financing and falling costs of membrane technology, drinking waste water will inevitably have to become the norm rather than the exception.

With inputs from Rahul Wadke, Tina Edwin, Poornima Joshi and TV Jayan

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Published on July 16, 2018
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