Wastewater Reuse: Key to sustainable urban water resource management

Key to sustainable urban water resource management

Arun Lakhani, Chairman and Managing Director, Vishvaraj Infrastructure Limited

About 80 per cent of the water supplied to towns comes back as sewage and such a large volume of water available within a city has to be treated as a water resource and not waste.

Various studies suggest that wastewater treatment in India is grossly inadequate. Larger towns are treating 30 per cent of the sewage on average, whereas smaller towns are treating as little as 2-3 per cent. Out of approximately 60,000 million litres per day (mld) of sewage that is generated on a daily basis, only 20,000 mld is getting treated. The untreated sewage contaminates waterbodies and the environment, posing a serious threat to public health. The reasons for this low treatment capacity are essentially the unavailability of funds and inadequate technical capability with the urban local bodies (ULBs) to develop and operate sewage treatment plants (STPs). So, untreated sewage is a menace that remains unresolved till date.

On the other hand, sewage is untreated water that is available within the city premises. If treated to the desired level, it can be an excellent source of water for industries as well as agriculture. Countries like Singapore are using treated sewage water for potable purposes. We may not be able to use it for drinking because of the very high cost involved in treating it to a potable level and also because of the people’s mindset against consuming treated water. However, treated wastewater for agricultural and industrial use is quite achievable. Industrial use of treated sewage water will not only provide them water security but will also free up fresh water that is otherwise being used by industries, including power plants.

Government policies have been supportive of the reuse of treated water and one such policy by the Ministry of Power has made it mandatory for power plants to use treated sewage water if it is available within a 50 km radius of a power plant. The additional cost of this treated water is allowed as a pass-through in tariff by power plants, making the entire value chain financially sustainable.

Swachh Bharat Mission, which also supports sewage treatment, is high on the government’s agenda. This exercise intends to invite towns to undertake sewage treatment and make use of the available schemes for the sector. It also aims at providing project frameworks for towns by developing models such as engineering, procurement and construction, hybrid annuity or public-private partnerships (PPPs), based on the local realities of sewage availability, current treatment capacities and reuse possibilities.

Treating sewage has two important components – development of treatment infrastructure and operations and maintenance of the STPs so as to get the desired outlet parameters on a perpetual basis. Both aspects need funds as well as technical bandwidth. So, in a country like India, we will have to innovate project development models that are financially self-sustainable and create a value chain that will benefit all elements of the ecosystem.

The first manifestation of this thought is under implementation in the city of Nagpur. The city has already taken lead on the urban water supply side by successfully demonstrating the first full-city-level 24×7 water supply project on the PPP model. Nagpur is now witnessing another concept of reuse getting implemented on a very large scale for the first time in the country.

Nagpur gets a daily supply of 700 mld of potable water. As a thumb rule, 80 per cent of this quantum comes back as sewage. Thus, the city produces approximately 550 mld of sewage and it had a sewage treatment capacity of only 100 mld. The untreated sewage typically went into the Pivli, Pohra and Nag rivers and subsequently, the Gosikhurd dam, contaminating these major fresh water and irrigation sources. This situation is very similar to other cities in the country. However, the difference is that the authorities in Nagpur initiated timely action.

Local non-government organisations alerted the civic authorities to the alarming rise in the organic contamination of water and its hazards for villages in the vicinity of the Gosikhurd dam. A legal inquiry followed and the high court ordered action to bridge the gap with immediate effect. As ULB, it was financially impossible to establish a system to meet the requirement of increased and efficient sewage treatment. The municipal authority of Nagpur took the PPP route with a focus on the reuse of treated sewage water.

The project involved collecting 200 mld of sewage from three rivers and augmenting the existing 100 mld STP to 200 mld. The scope also included O&M of the entire facility for 30 years, post-commissioning. The project was structured on the PPP model, wherein the entire capital investment was to be made by the operator. Vishvaraj Environment Private Limited (VEPL), a subsidiary of Vishvaraj Infrastructure Limited (VIL), was selected as the operator through a competitive bidding process.

The construction of the new 200 mld STP was completed within the prescribed construction period and the operation of the plant also commenced. However, what makes the project really interesting is the reuse agreement signed with the local power utility. The power generation company has signed an agreement to purchase 150 mld of tertiary treated water from this STP. All the stakeholders in the Nagpur reuse model benefit in some way or the other.

Nagpur city and its citizens: The untreated sewage will not only be treated but will also be reused, and the additional potable water that is being used by the thermal power plant will be made available to the city. The water source of the city will be saved from pollution from untreated sewage to some extent, leading to a reduction in water borne diseases and curbing the pollution of the downstream waterbodies.

The thermal power plant: The thermal power plant will get a stable source of water. In the face of scarcity of water, when water supply for agriculture and domestic supply is given preference, the thermal power plant will not have to be shut down and suffer losses due to the unavailability of water.

The municipal corporation: The project is developed through 100 per cent private investment and so the municipal corporation does not have to make an upfront capital investment in the project. The STP, which is a cost centre for the ULB, will earn royalty from the sale of treated water, making it a cash-neutral business.

India is facing many challenges, and large-scale untreated sewage is just one amongst them. The challenges need to be resolved through out-of-the-box ideas, which are very much Indian and that can offer a solution in a financially and environmentally sustainable way. Reuse of treated water by industries is one such idea that can address sewage treatment issues on a national front. The Nagpur reuse project is just a humble beginning and other towns in the country can come forward to embrace the concept and contribute to the Swachh Bharat Mission initiative.

(Arun Lakhani has been advising and providing technical inputs on urban water supply and the Wastewater Treatment and Reuse Project to NITI Aayog through VEPL)