HomeSpotlightIs ZLD next destination in our urban planning?

Is ZLD next destination in our urban planning?

Wherever man and animals exist, they are bound to create wastes, both solid and liquid. Though, of late, much noise is being created about the management of solid waste in cities, treating the liquid waste has almost remained neglected. It doesn’t mean that the problem of untreated liquid waste is minor one and unless some immediate actions are not taken the problem may soon take gigantic proportions.

Lack of infra to treat waste water

In fact, discharge of untreated sewage in water courses both surface and ground waters is the most important water polluting source in India. What’s even more worrisome is the fact that we have not yet realised intensity of the problem yet. Our seriousness (or lack of it) is revealed in the infrastructure we have built up to tackle this problem. For example, out of about 38000 million liter per day of sewage generated treatment capacity exists for only about 12000 million liter per day. Thus, there is a large gap between generation and treatment of wastewater in India. Even the treatment capacity existing is also not effectively utilized due to operation and maintenance problem. Operation and maintenance of existing plants and sewage pumping stations is not satisfactory, as nearly 39% plants are not conforming to the general standards prescribed under the Environmental (Protection) Rules for discharge into streams as per the CPCB’s survey report. In a number of cities, the existing treatment capacity remains underutilized while a lot of sewage is discharged without treatment in the same city.

ZLD in city planning

Zero Liquid Discharge (ZLD) is a well-known concept but currently associated mostly with industries. However, it is time to extend ZLD concept to Indian cities as well. We all are aware of climate change manifesting its threats through water related issues in the form of floods, inundation, sea level rise or droughts. Many Indian and global cities are already facing threats of acute water security and to manage and mitigate the risk we need to emphasize on recycle and reuse of treated wastewater.

But we are approaching the problem with baby steps when the urbanisation is picking up pace and nearly half the population of the country is expected to migrate to cities by 2050. So far it has remained an aspirational goal with most of the Municipal Corporations lacking even the basic amenities for the purpose.

Treatment capacity is unevenly distributed

There are 35 metropolitan cities (more than 10 Lac Population) and these cities estimated to generate 15,644 million Litre Per Day (MLD) of sewage. Meanwhile, the treatment capacity of these Municipal Corporations is only for 8040 MLD. Further, among the Metropolitan cities, Delhi has the maximum treatment capacity that is 2330 MLD (30% of the total treatment capacity of metropolitan cities). Next to Delhi, Mumbai has the capacity of 2130 MLD, which is 26% of total capacity in metropolitan cities. Thus, Delhi and Mumbai in combination have 55% of treatment capacity of the metropolitan cities. However, in case of some cities such as Hyderabad, Vadodara, Chennai and Ludhiana and Ahmedabad treatment capacity meets the volume of generation.

Some cities have taken a lead

Meanwhile, its heartening to note that some cities have taken the issue very seriously and have set an ambitious target for themselves. If everything goes as planned, Surat city may become India’s first ‘Zero Liquid Discharge (ZLD)’ city. According to Mr. Banchhanidhi Pani, Municipal Commissioner, Surat Municipal Corporation (SMC), the corporation is planning to achieve 50% ZLD by 2025 and 100% by 2030. Currently SMC reuses nearly 30% of the wastewater. In 2014, the tertiary treatment plant was initiated to cater to the water demand of industries. This was initially started as a demand-based approach and 35 MLD treated wastewater was made available but today the demand reached 115 MLD for industries. This model has proved economically beneficial as SMC is receiving 140 crores which is above operational and maintenance costs of all existing STPs. Though this is mainly for industries it is also used for landscape, construction and recreational purposes and out of 950 MLD, more than 30% of wastewater is reused. SMC is now aiming to achieve 50% by 2025 and 100% by 2030 to achieve the aim of ZLD.

In Nagpur, PPP model has been implemented wherein 200 MLD of wastewater is treated and 190 MLD treated water is given to thermal power plant. Nagpur is generating close to 600 MLD and more than 300 MLD is being treated currently.

Chennai is currently generating 727 MLD secondary treated water, out of this 110 MLD has been treated and supplied to industries. Chennai has plans to treat 550 MLD to recharge groundwater which will be used for potable uses as well.

Trade in wastewater reuse certificates

Maharashtra and the 2030 Water Resources Group (WRG), a partnership hosted by the World Bank, are planning to launch a platform enabling trade in wastewater reuse certificates (WRCs), in an attempt to incentivise greater levels of reuse. The Tradable Certificates – one per 100m3/d of wastewater reused – are planned to be issued initially to ten large industrial water users and ten municipal corporations in a pilot in Maharashtra state. The organisations will have to meet established reuse targets, with underperforming organisations expected to buy surplus certificates from organisations that have passed their target. The trading certificate system is decided based on water budget allocation and has components of penalty and extra credit points for over achievers.

How to go ahead?

India being a vast country it may not be useful to have single rule/standards applicable to the whole country. Instead, we need to have situation and area specific standards for reuse purposes. A tariff-based approach may help us to avoid over exploitation of water in cities or districts. A mandatory provision may have to be introduced to replace the usage of freshwater with treated reuse water for all the non-potable uses in industries. Similarly, there is need to pay enough attention to pricing of the different treated water and the government may have to come out with necessary policy initiatives in this regard. Further, we may have to incentivize the whole concept (of reuse of treated water) to push for implementation at a larger scale.

We may also face challenges in the form of transportation and matching demand and supply both in terms of quality and quantity for which suitable solutions need to be found out at the local levels.

The entire exercise involves huge capital expenditure and therefore private sectors’ involvement is needed. The government initiatives on various fronts should be complemented by private sector participation which should either be driven by regulations or through market linked incentive systems. There is also a need for agriculture and other sectors to collaborate with academic institutions to provide research solutions and administrative support in regulatory and operational aspects.

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