With the rapidly increasing urban population, water pollution and water scarcity are also increasing. Thus, it is imperative for communities, businesses and governments to deal with these issues. Sewage management is essential for keeping water sources clean and maximising the efficiency of reclaimed water processing.
Automated solutions for sewage treatment
The automation of sewage treatment plants (STPs) and facilities improves the efficiency of the system and reduces the manpower requirement. To this end, supervisory control and data acquisition (SCADA) systems have been widely deployed across the country. SCADA enables remote monitoring of water supply distribution systems and their various process parameters such as water quality (pH, turbidity and residual chlorine), process variables (flow level and pressure) and control elements (electric actuators for valves). Treatment plants in various cities are now being monitored through SCADA.
In March 2022, the Coronation Pillar STP was inaugurated in Delhi. It is a fully automated STP with a treatment capacity of 310 million litres per day (mld). The STP will treat the wastewater generated from Shakti Nagar, Kamla Nagar, Roop Nagar, Delhi University Campus and Nehru Vihar, among other areas. Sewage from unauthorised colonies such as Swaroop Nagar, Bhalswa, Sant Nagar and Wazirabad will also be treated there, which will help in cleaning up the Yamuna river. A SCADA system has been installed at the STP for operating the machinery remotely and ensuring smooth functioning. The plant will have features such as mechanical dewatering of sludge and will eliminate the requirement of sludge drying beds.
In another important development, the Delhi Jal Board (DJB) is planning to automate 116 sewage pumping stations (SPSs) around the city by installing internet of things (IoT) devices to prevent overflow and allow timely discharge from these pumps into STPs. Under this system, as soon as the sewer water crosses the threshold level in the tanks situated in these stations, the information will be sent to DJB through the monitoring device, in case the pumps have not been turned on. In such a situation, the time to start the SPS will easily be ascertained so that the sewage can be pumped towards the STP on time and there is no additional pressure in the sewer line. Due to the untimely operation of SPSs, several problems including sewage overflow and sewer line blockage were on the rise in many places. This initiative, in addition to preventing overflow, will prevent clogging of sewer lines, improve the performance of Delhi’s STPs, and keep drinking water supply safe from getting mixed with sewage lines.
ENVIRO is a key industry player that offers automation and control systems for plants. It helps improve the monitoring and control of operations and increase efficiency at lower costs. The company has implemented programmable logic controllers in the SCADA system at 23 SPSs and six STPs of the Surat Municipal Corporation for centralised process monitoring and control. The operation of various STPs and SPSs in Surat City is controlled from a central location. Remote access and control of plant process parameters are being achieved by applying superlative online instrumentation. This is a key distinctive feature of this project.
The water treatment facilities and distribution system in Ahmedabad Smart City are also being monitored by a SCADA system. The project covers three water treatment plants (WTPs) and 148 water distribution stations. In a similar development, the Pimpri Chinchwad Municipal Corporation has brought all the STPs in its jurisdiction under a central monitoring system. The entire sewerage network, comprising a system of 13 STPs and 33 SPSs, is being monitored by SCADA system monitors. A master control room has been set up with engineering and operator stations. The installation of the centralised SCADA system involved a total investment of Rs 42 million.
The under-construction Okhla STP is also being developed as a fully automated STP with a SCADA system. It will be an integrated plant that will not only treat sewage, but also have a complete sludge management facility. The plant will have the largest ultraviolet disinfectant system in the country for the removal of faecal coliform from water. Meanwhile, Nashik Municipal Smart City Development Corporation Limited has plans to implement SCADA and automatic meter reading/advanced metering infrastructure meters in the city. With this, the water supply will be monitored from the start point (WTP) to the end point (consumers).
Another digital solution that is being deployed in sewage treatment and management systems is the geographic information system (GIS). This technology is designed to capture, store, manipulate, analyse, manage and present all types of geographical data. Meanwhile, radio frequency identification tags are installed at sewage collection points to read information about collection vehicles and send alerts to the sewage collection authorities.
In this regard, the Kerala Water Authority has come up with a new tool using GIS for optimal site selection of STPs. It is undertaking a study to find the most optimal sites for STPs using the GIS-based multi-criteria analysis in Elamkulam, Kochi. Further, GIS and management information systems are being deployed in Varanasi to effectively monitor the city’s civic infrastructure, such as the water supply and sewerage network, and improve the financial and operational performance of the urban local body.
New projects are also being approved for automated sewage treatment. Interception and diversion work and three new STPs in Dehri-on-Sone, Bihar, have been approved. These will include the development of the three STPs (one 11 mld STP near Shiv Mandir, one 7 mld STP near Dalmia Nagar and one 3 mld STP near Islam Ganj) including necessary ancillary infrastructures, UV disinfection, SCADA and online monitoring systems. The Atal Mission for Rejuvenation and Urban Transformation 2.0 also emphasises the deployment of SCADA systems and smart solutions for sewage treatment.
Going forward, newer technologies such as artificial intelligence (AI), machine learning (ML) and digital twins will emerge as advanced tools for wastewater treatment and management. At present, these technologies are still at a nascent stage in India and their implementation by local bodies has not picked up pace.
An emerging technology in the management of STPs is digital twin. Digital twin is a new-age technology, that facilitates the virtual representation of processes, assets and environments. It can be used for real-time monitoring, predictions and automated responses. These functionalities leverage ML and hydrological modelling based on big data acquired from IoT sensors. Meanwhile, AI is a cost-effective solution with an increasing number of use cases, from healthcare to wastewater treatment. When it comes to the sewage treatment process, AI can help address issues such as sludge expansion, and improve aeration and pump efficiency. Under ML, which is a subset of AI, an algorithm is trained to detect abnormal data patterns (or correlations of patterns) regardless of whether the control thresholds have been breached. With ML, algorithms are looking for behaviour patterns even within thresholds. This will help in identifying issues in the treatment facilities. It is expected that in the coming years, these technologies will be deployed for managing and treating sewage in the country, thereby increasing the efficiency of systems and reducing costs.