Utilities are increasingly using technology to improve citizen services and supply quality. Sewage treatment plants (STPs) are one area to have witnessed the adoption of advanced technology solutions in recent times. STPs earlier operated on outdated technologies such as lagoon aerators that needed both land and power and failed to meet effluent outlet parameters. The use of these outdated technologies resulted in sea pollution and hazards during monsoons when the seawater rises and inundates the low-lying areas of cities such as Mumbai and its suburbs.
To address this challenge, the Brihanmumbai Municipal Corporation (BMC) has been leveraging different technologies such as continuous sequencing batch reactor (CSBR) and membrane bioreactors.
Bhandup project
BMC announced seven STP projects that aim to comply with effluent quality norms, prioritise power efficiency and ensure environmental friendliness. Of these, JWIL Infra Limited has secured the Bhandup project and is involved in the development of the STP. The Bhandup STP, with a capacity of 215 million litres per day, represents a pivotal infrastructure project in Mumbai’s wastewater management system.
Adoption of CSBR biological treatment
technology
The Bhandup STP project involves the implementation of cutting-edge continuous sequencing batch reactor (CSBR) technology, an innovative solution imported from South Korea. This marks a significant milestone, as India is adopting this technology for the first time. CSBR technology was selected for its operational ease, low carbon footprint, lower energy consumption and overall low life cycle cost. The patented technology amalgamates the A2O (anaerobic-anoxic-aerobic) process with a sequential batch reactor (SBR). It operates on a continuous flow basis, ensuring constant and modified flow within the SBR system. This approach allows for continuous operations while retaining the benefits of the SBR process, such as versatility in handling varying influent conditions and high treatment efficiency. In addition, the A2O process ensures biological nutrient removal (BNR) of phosphorous and nitrogen, and requires lower consumption of chemicals to remove phosphorus than other methods.
In a CSBR system, wastewater undergoes treatment in sequential batches within a single reactor vessel. The process consists of several stages, such as filling, reaction, settling, decanting and idle phases. However, unlike traditional SBR systems, CSBR operates continuously, enabling a more consistent flow of treated effluent. The decanting system in CSBR works on the hydraulic (siphon) principle, which has several advantages such as zero head loss, zero interruption and maintenance-free actuators.
Advantages of CSBR
CSBR technology provides two symmetrically configured SBR cells to alternately decant treated supernatants with continuous effluent discharge, eliminating the need for flow equalisation and minimising the size of downstream treatment facilities. It uses constant liquid-level operations, avoiding the high head loss and low tank volume utilisation efficiency typical of variable-level SBR operations. Further, it provides dedicated reaction zones for efficient anoxic, anaerobic and aerobic treatment of wastewater, with well-understood BNR mechanisms and a clear definition of each cell’s role. The technology also arranges these cells as non-major treatment cells at the effluent end of the system, minimising equipment duplication and significantly reducing system costs.
With CSBR’s lower power consumption, extensive Class A sludge treatment will lead to higher biogas production, and ultimately, more electricity generation. This will enable the Bhandup plant to move towards achieving a zero-carbon footprint.
Manori desalination plant
BMC is also actively adopting technologies like desalination to enhance its water supply network. Further, STPs are being constructed with modern technologies such as membrane bioreactors. Technologies like bioremediation are also being deployed to reduce the pollution load of wastewater entering waterbodies. Moreover, they have been successfully implemented in some of the existing wastewater treatment facilities. As a natural and biological technology, it is less energy-intensive and requires minimum infrastructure, lowering the capital cost of the project. Upon achieving successful results, this technology can be integrated with STPs.
One such project using bioremediation technology is the Manori desalination plant with a capacity of 200 mld, which can be further expanded to 400 mld. The project has been approved by the Maharashtra Coastal Zone Management Authority
and is aimed at enhancing water security in the city.
Conclusion
Water and wastewater projects require all players and stakeholders to make the necessary changes to adopt technologies that address global warming and climate change. Furthermore, the energy-intensive nature of these projects must be addressed through energy-efficient and smart operations. This can be facilitated by deploying artificial intelligence-, machine learning- and internet of things-based technologies, which can be further used for predictive maintenance of plants. In this regard, efficient and effective technology selection must be prioritised to reduce operational costs at the beginning of the project itself.
