Turning Wastewater Into Energy

Novozymes has developed a groundbreaking biogas plant that turns wastewater at its Franklinton plant into energy to help power the plant.

FRANKLINTON — Angela Walsh bends down to look into 12 glass bottles that are locked into positions on an agitation table. The table slowly moves back and forth, mixing the solutions in the bottles.

“They’re just like you and me,” Walsh says. “If we eat something that upsets our stomach, we’re not going to be very healthy and what’s happening in there is the same concept just at the cellular level.”

Walsh is the Environmental and Utilities Manager for Novozymes at its Franklinton plant. She’s talking about, and even talking to, the cellular organisms living in the bottles on the table. It’s her job to monitor the health of the little creatures.

“We want to make sure our operation is reliable, so we want to minimize that risk of them ingesting something they shouldn’t,” Walsh adds, smiling. “We want to make sure they are happy, and it looks like they are.”

The water appears to be filled with tiny pieces of debris, but it turns out the little dots floating around in the bottles are actually living cellular organisms. The larger black objects are a medium for microorganisms to live on. And all of those microscopic creatures are happily munching away on what they find in the wastewater they are living in. You can tell they are happy from the bubbles on top of the water.

“The little organisms uptake the nutrients in our wastewater and convert it to methane gas and carbon dioxide, so our wastewater is their food,” says Walsh.

The wastewater comes from the Novozymes’ plant. The company produces enzymes for consumer, agricultural, and pharmaceutical products. Scientists monitor what’s happening in the jars because it’s a miniature version of what’s happening in a new biogas reactor just outside the main production facility.

The giant three-story tank is surrounded by a maze of pipes of varying sizes, all connected by valves of different sizes and colors. The tank holds 237,000 gallons of wastewater. Since it is difficult to keep tabs on the conditions inside the main tank, researchers duplicate the conditions in the bottles in the lab.

“Since the granular organisms live in the bottom third of the reactor, the wastewater is pumped in at the bottom and it pushes everything up, to keep things moving,” explains Dean Sawyer, an environmental engineer at Novozymes. “We’ve also added two cell plates that separate the gas from the water. So as the water is circulating through the tank, the objective is to keep the creatures in the water and passing through the water, and the gas that is generated is taken off the top.”

The reactor is the first of its kind for a life sciences company in the region. The organisms in the tank process about 20 tons of organic material every day from the factory’s wastewater system.

The gas generated in the facility will be used to power the factory along with the reactor. Once it’s removed from the tank, the gas is treated to remove hydrogen sulfide, which makes it safer. It is also compressed and moisture is removed. The gas will be used to make steam and hot water. It’s estimated the plant will generate enough gas to power about 570 homes for a year.

Until now Novozymes treated the wastewater generated by its plant in a five-million-gallon lagoon alongside the factory. It was an aerobic treatment facility, which means the water is bubbled and churned so the microorganisms in the lagoon could process the waste. The new system replaces the lagoon. And even though the tank in the biogas plant is large, it is easy to see the tank is a shadow of the size of the lagoon. But that’s ok, because an anaerobic treatment system is much more efficient so it doesn’t require all the aeration space that was needed by the lagoon.

That’s not to say Novozymes is giving up on aerobic treatment for wastewater. The old lagoon will be closed but it won’t be filled in. The lagoon will be needed when the biogas plant is close for maintenance.

And the water isn’t perfectly clean when it leaves the biogas plant. It is sent through a smaller aerobic treatment system before it is pumped to the county wastewater treatment plant or used to irrigate nearby farms.

And the biogas system is so carefully balanced that any change in what is being manufactured in the plant requires an adjustment in the reactor so the microorganisms aren’t killed.

But when the little creatures inside the giant tank in the biogas facility are happy, they are saving energy, water and raw materials. That’s why all eyes are watching those bottles slowly swirling around on a tray in a lab.

“We’re always looking at the bubbles and for the amount of gas that’s produced because that gives us an idea of how healthy the organisms are,” says Walsh, laughing at the thought of how important bubbles are. “The healthier the organisms are the more biogas they produce. And it also gives us an idea ahead of time that something is coming down the drain and something in the water is making them sick, and that gives us a chance to plan for any obstacles or roadblocks.”

Related Resources: