The Delhi Jal Board (DJB) is implementing several action plans to deal with the city’s accentuating water crisis. The city currently generates around 953 million gallons per day (mgd) of water against an estimated demand for around 1,380 mgd. To bridge this gap, DJB plans to map water demand and supply at the ward level to identify areas that need improvement in water management. Stabilising the biochemical oxygen demand (BOD) levels of water is also being emphasised.
According to the Economic Survey 2022-23, DJB’s wastewater treatment capacity has witnessed a positive growth of 13 per cent from 906 mgd in 2014 to 943 mgd in 2022. The integration of advanced technological and digital solutions is being initiated in various water supply and treatment projects. These initiatives are the adoption of NEWater technology, Intelligence Self-Administered Self Monitored Automatic Chemical Dosing (ISASMA-CD) technology, water ATMs, and internet of things (IoT)-enabled monitoring devices.
A look at some of the smart solutions that DJB is implementing, their benefits and the authority’s future plans for technology deployment…
Advanced techniques deployed in ongoing projects
Most of the sewage and water treatment projects undertaken by DJB utilise innovative treatment methods to achieve higher efficiency. For instance, the Wazirabad water treatment plant (WTP) uses the NEWater technology from Singapore, which processes water in three stages. The first stage is microfiltration, wherein the water is passed through membranes to filter out microscopic particles and bacteria. This is followed by reverse osmosis (RO), wherein the water passes through a semi-permeable membrane that has very small pores. This enables advance filtration of water. In the third stage, ultraviolet (UV) disinfection takes place, wherein both bacteria and viruses get removed, thereby making the water fit for drinking purposes.
In another example, DJB has decided to install a new filter house with modern technology at its WTP in Nangloi. The WTP’s capacity augmentation plan was approved in October 2022. The plant currently has 16 filter beds that require upgradation. Post installation, the new filter house will be able to treat 10-15 per cent more water. It will also be able to take more pollutant load.
DJB has also deployed ISASMA-CD for treating water at its 25 mgd Yamuna Vihar STP and 16 mgd Okhla STP. The technology reduces the BOD and the total suspended solids (TSS) to less than 10 parts per million (ppm). It operates through artificial intelligence-based software and shares real-time data. A significant improvement in water treatment has been recorded at both these plants after the adoption of ISASMA-CD. The TSS and BOD levels earlier observed at the Yamuna Vihar STP were 125 ppm and 90 ppm, but have now dropped to 8 ppm and 7 ppm respectively while the same have reduced to 8 ppm and 5 ppm respectively at the Okhla STP.
Several technological advancements are taking place in septage collection and transportation services. Technological tools, such as GPS, are being leveraged for tracking and monitoring vehicles carrying septage from different parts of Delhi. The vehicles are monitored by GPS for any defaults made in the collection and disposal of septage. To this end, 180 such registered vehicles will be monitored in Delhi through GPS in accordance with the Septage Regulations, 2018. This would help achieve efficient collection of septage, thereby reducing its careless discharge into drains or rivers and thereby allowing its subsequent treatment.
Upcoming technological interventions
New STP projects as well as the old/existing ones underdoing upgradation are making use of IoT-enabled monitoring devices and sensors for better efficiency. To this end, the sewer pumping stations (SPSs) at STPs are being automated with IoT technology for real-time monitoring of operations.
DJB has planned to use IoT sensors across 116 SPSs to prevent instances of water overflow. These sensors will ensure the timely flow of water from the pumps to the STPs, which, in turn, will help reduce the pressure on sewer lines. As soon as the water levels will cross the desired threshold of water tanks, the device would send information to the control centre to switch on the pumps. This is expected to address issues such as clogged sewer lines and the discharge of treated water into them.
Furthermore, RO, ammonia removal and ozonation plants are being planned as advanced methods of water treatment. RO plants use pre-treatment techniques such as softening, dechlorination and anti-scalent treatment and later pass the water through a semi-permeable membrane to purify the contaminated water. DJB plans to set up 500 such RO plants with tube wells in various unauthorised colonies of Delhi that are water deficient. To begin with, 30 RO plants with 50,000 litre per day capacity would be installed as part of a pilot project. Additionally, radio frequency identification cards would be issued to the residents in the area for obtaining water supply.
An ammonia removal plant along with an ozonation plant is being planned to be set up at Wazirabad. The ammonia levels of the Wazirabad barrage have reached the 3 ppm, surpassing the maximum limit of 2 ppm, owing to industrial wastewater discharge from Haryana. The functioning of the WTPs at Wazirabad is hugely impacted by these increased levels. The proposed ammonia removal plant will use the method of ammonia stripping, which is a desorption process to reduce the ammonia content in wastewater. The ozonation plant, meanwhile, will use an advanced oxidation process involving the production of reactive oxygen that kills various organic compounds and microorganisms.
In another development, DJB has decided to go ahead with in-situ treatment of the Najafgarh, Supplementary and Shahdara drains that contaminate the Yamuna river. The treatment involves creation of dams, chemical dosing, bouyants, aeration and floating wetlands as techniques of water filtration. The water in the drains is treated repeatedly by these techniques before being discharged into the river. While aeration devices and chemical dosing aids in reducing phosphates in the wastewater, floating wetlands help in absorbing the contaminants through the use of specific plant species. These plants are placed in floating bamboo rafts that sustain in water for longer periods of time. This treatment is cost-effective and serves as a decentralised solution for wastewater treatment.
The way forward
Going forward, DJB will continue to focus on adopting smart and innovative techniques and technologies to ensure regular water supply and improve water quality. To this end, it will be developing a smart operation and management framework for water and wastewater infrastructure under an MoU with the Indian Institute of Technology, Delhi. This is being seen as a positive step forward for creating shared knowledge platforms and disseminating information for understanding water and wastewater management in the city. Further, to overcome water shortages in the city, the installation of flow meters at underground reservoirs to monitor the water flow rate and usage is being explored.