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BROOKINGS, S.D. 鈥� Nanobubbles may be the answer to dairy wastewater treatment issues.

These gas bubbles are not visible to the human eye, but they work in a powerful way to improve the quality of the wastewater that is discharged from dairy manufacturing plants. Nanobubbles are tiny pockets of gas, like oxygen or air, suspended in a liquid. They can be formed naturally in crashing waves or waterfalls or can be created through nanobubble generators.

Nanobubbles, which are 2,500 times smaller than a grain of salt, have been utilized in a wide variety of ways in different industries for the past few years.

As dairy manufacturing grows, so does their effluent 鈥� or liquid waste discharge 鈥� treatment plant issues. A lot of companies don鈥檛 have the scale to increase their waste treatment at the same scale that they are increasing production.

Contributed

Maneesha Mohan, South Dakota State University鈥檚 Alfred Chair in Dairy Manufacturing and an associate professor in the Department of Dairy and Food Science, has been researching nanobubbles in different industries for many years. Thanks to funding from the South Dakota Water Resources Institute, Mohan has been able to research the application of nanobubble technology in dairy wastewater treatment.

Nanobubbles are not like normal gas bubbles, Mohan explained. Nanobubbles are so small that they can stay stable within a liquid system for extended periods of time.

鈥淓ven days to a few months,鈥� she said. 鈥淪o basically, we can make them stay there for a while and interact with whatever is there in the liquid system for a longer period of time.鈥�

In dairy effluent treatment, the high levels of organic acid, minerals and other matter makes it hard to be treated.

鈥淭here will be a lot of organic solids in your effluent and a lot of the cleaning minerals, acids and alkali that actually makes it very hard to handle the effluent,鈥� Mohan said.

Dairy processing plants are often making multiple products, which means they have huge fluctuations in the amounts of organic matter and wastewater that they have. Sometimes, these processing facilities don鈥檛 have time to handle the waste, and they must hire someone to haul it away, which is expensive.

Dairy wastewater, if not properly cleaned, also becomes an environmental problem because it is discharged into bodies of water.

鈥淚t will affect whatever aquatic life and any other, you know, plants and animals that are surrounding these water bodies as well,鈥� Mohan said.

Of course, the plants have to meet EPA standards, Mohan said, but it鈥檚 better to keep the nitrates, phosphates and all organic matter much below those levels.

By using nanobubbles, they are able to improve the efficacy of water treatment. The nanobubbles interact with the organic matter and minerals.

鈥淭hey break it down and oxidize it, so basically, the effluent treatment plant can more efficiently handle all the effluent that the dairy processing plant is producing,鈥� Mohan said.

There has been a lot of industry interest in this research, Mohan said. in Milbank, South Dakota, has been an industry collaborator in Mohan鈥檚 research. The company installed a nanobubble generator. They were able to test the efficacy of the nanobubble generator in the company鈥檚 effluent plant.

鈥淚t actually improves the efficacy quite a bit,鈥� Mohan said.

There has been a 15 to 20% decrease in volume of biology oxygen demand and chemical oxygen demand after using the nanobubbles. Using air is a relatively inexpensive way to get this level of improved efficacy. It is also a more sustainable solution rather than hauling the wastewater away.

鈥淲hich is significant thinking that nanobubbles are pretty environment friendly because for that project we only used air as nanobubbles,鈥� Mohan said. 鈥淲e can use a number of gases, but it鈥檚 much more cheaper to use air.鈥�

This technology is very new, but Mohan says she anticipates other dairy companies will start utilizing nanobubbles in the effluent plants in the future. She says they need more studies researching nanobubbles as well.