Smarter Wastewater Treatment: How Nanobubbles Improve Water Purification 

At the spearhead of innovation, we are leading a groundbreaking project to transform the industry at the nexus of fluid dynamics coupled with tangential technologies for water treatment. Our industrial collaboration with L&T is creating a new frontier for the future of wastewater treatment by optimizing ozone-based disinfection in the ozone contact tanks (OCT) for enhanced water treatment. We aim to blend advanced CFD with nanobubble technology and transform the utilization of ozone in disinfection. 

Nanobubble technology refers to the creation of minuscule gas bubbles, measuring less than 200 nanometers in diameter, within liquids. These nanobubbles possess distinct characteristics, including a large surface area, prolonged stability in water, and improved gas transfer efficiency. They are utilized in various fields such as wastewater treatment, agriculture, healthcare, and industrial cleaning to enhance oxygen levels, eliminate pollutants, and facilitate chemical reactions. In the context of wastewater treatment, nanobubbles improve the delivery of ozone and the efficiency of purification processes, leading to better breakdown of pollutants while minimizing chemical use and lowering operational expenses.

How does it work?

1. Gas Injection: A selected gas (e.g., oxygen, ozone) is infused into the liquid using a nanobubble generator.

2. Bubble Formation: Nanobubbles form through cavitation, shear forces, or gas dissolution methods.

3. Stable Suspension: Unlike regular bubbles, nanobubbles don’t rise quickly but stay in the liquid, improving gas transfer efficiency.

4. Interaction with Contaminants: The bubbles collapse, generating free radicals (if ozone is used), breaking down pollutants, and enhancing purification.

L&T has partnered with us on a great initiative to clean the Yamuna River and transform wastewater treatment in the region. To rejuvenate the Yamuna River, we will simulate the advanced nanobubble technology approach coupled with ozone-based disinfection, optimizing the ozone contact tanks (OCT) for more efficient water purification using computational methodology. 

Nanobubbles, which are between 100 and 1000 nm in size, exhibit remarkable properties that set them apart from conventional bubbles. But what makes these tiny bubbles so powerful? Their small size allows for highly efficient ozone transfer to water because of their surface-to-volume ratio. The longer bubble residence time leads to improved disinfection efficiency. 

What if we could achieve better results without introducing harmful chemicals into our water systems? Nanobubbles offer chemical-free solutions and not just efficiency. Also, nanobubbles produce hydroxyl radicals upon collapsing—a strong oxidant—making them ideal for wastewater treatment.

This approach outperforms traditional methods as a sustainable and cost-effective solution, saving time and resources. It provides an environmentally conscious alternative, optimizing operational efficiency and promoting long-term ecological health. 

We’re catalyzing the full potential of nanobubbles in an ozone contact tank by utilizing computational methods such as Computational Fluid Dynamics (CFD) and Population Balance Modeling (PBM). The integration of these advanced modeling techniques enables us to replicate the behavior and population of nanobubbles and their interaction with water in real time, helping us understand their effectiveness. 

CFD allows us to see flow inside the OCT, examine bubble distribution, predict the duration of the residence time, and even examine the mass transfer of ozone. When we combine that with PBM, we can predict the bubble’s size distribution and number density, which are important variables in determining how efficiently the nanobubbles will act. By adjusting the system, we can simulate the exact environment of the OCT and maximize the bubble dynamics. 

This collaboration between Paanduv and L&T has broad implications. The goal is to examine the nanobubbles' efficiency compared to more conventional methods such as diffusers and other sizes of bubbles, such as macrobubbles and microbubbles. We will determine which approach has negligible buoyancy due to which it mixes well with the water in only a few seconds and can significantly reduce water retention time with higher mass transfer. Imagine if you could treat water in a few seconds rather than hours and days; how much energy would it save? However, ozone generation is also an energy-intensive process, yet it can save energy compared to traditional ozone treatment. Unlike traditional ozone gas bubbling, where much of the ozone escapes, nanobubbles retain ozone longer, reducing ozone wastage and the need for continuous high-dose injections.

That’s not it, nanobubble technology can reduce the water treatment plant size significantly, providing room for process intensification, which is a novel concept. 

However, the scope of this project extends beyond that. By scrutinizing nanobubble technology, we seek to advance the field of water treatment technology. This could enhance wastewater treatment and lead to advancements in wastewater treatment.

As we break ground in water treatment innovations, one fact stands strong: nanobubble technology holds the vigor to redefine the future of purification. Advanced simulation methods and the eco-friendly properties of nanobubbles combine to provide a trifecta of answers to some of the difficult problems in water purification.