5/6/18 Food Pulper

The digester at West Lafayette Wastewater Treatment Plant processes food waste to help produce electricity and fertilizer.

A group of Purdue students has spent the last two semesters working to improve West Lafayette’s food-waste diversion program.

The team’s project is part of an environmental and ecological engineering senior design class. Loring Nies, a civil engineering professor, assigned the group to work with the Go Greener Commission of West Lafayette. He sent out an in-class survey to pair students with others that shared the same interests for an ecological engineering project, according to Jacob Corral, a member of the environmental engineering team.

The main goal of their project was to make an accounting system for all of the food waste, he said. They take into account how much gas is produced, how much emissions are saved, how much money is saved and a general record of how much food waste actually goes through the plant.

The digester has been collecting food waste to run the wastewater treatment plant for a little over 10 years now for West Lafayette, team member Robbie Beeler said.

“This program collects food from Purdue and the West Lafayette community, takes that food, puts it through an anaerobic digester, which forms natural gas,” Beeler said. “This natural gas is then put through micro turbines to produce electricity, and then that electricity is used to power the wastewater treatment plant.”

The food waste collected from Purdue gets ground up into a pulp known as “yack,” which is a heterogeneous substance that resembles coleslaw. It is then put into the digester to create methane, then into electricity. Without this partnership, the many tons of food waste that Purdue produces every month would be placed in a landfill, Beeler said.

“It’s a 100% renewable process and is very beneficial for the environment,” Beeler said.

“A lot of the funding is controlled by our client,” Beeler said. “A lot of the finances that we deal with is mostly handled outside our control at that point. We provide a layout for recommendations comparatively to actually handling the money.”

The senior design team recommends what grants the Go Greener Commission should apply for, where the city should put its money toward pickup locations for the food waste or extra bins. The money can come from many things, typically city external grants or money the city has allotted to give to the Commission.

“Additionally, we were tasked with updating the financial calculator of the entire program in general when it comes to pick up, the formation of gas and the use of electricity,” Beeler said. “Finally, they tasked us with the objective of creating a policy brief for the city of West Lafayette to get the gears going when it comes to better diversion practices when it comes to food waste.”

Beeler’s team is not the first to partner with the Go Greener Commission. A team last year created a plan to optimize the pickup of waste in the bins and other things about food waste.

“Coming out of 2020, coming out of the pandemic, they really wanted implementation,” Beeler said. “That’s kind of our job with them.”

The team uses data from previous years and from their own research to present to the Go Greener Commission. He said the team wanted to show the best way to implement these plans to fully immerse the community in the food-waste diversion program.

“The accounting system is one of our objectives. A major part, especially with regard to policy, is how can we increase community involvement in the food-diversion program,” Corral said. “The community awareness of the local program is extremely low.”

As of right now, Purdue is the dominant contributor to the conversion program, Corral said. In their research, the team found that 250,000 pounds of food waste were delivered last year to the wastewater treatment plant from Purdue University.

“There’s a large education benefit for not only students but residents of West Lafayette as well,” said Nathan DeMars, a junior on the team. “They can learn about the process that goes on at the water treatment plant and why sending their food waste there matters.”

Corral said he hopes that through the team’s policy they can increase awareness of the city’s program among the digesters at the wastewater treatment facility.

“There are tangible and intangible benefits of the program,” DeMars said. “Diversion-wise, we can see more food not being wasted by as many residents, which means more money saved by the city.”

Kyle Miller, another member of the team and a junior in environmental engineering, said the project also offers an opportunity to create energy savings. He said that there were approximately 30,000-kilowatt-hours produced from this anaerobic digestion process last year.

Even after the electricity is derived from the food waste, it can be used as fertilizer for local farmers in their soil after it’s saturated in a lagoon. This provides more potential for the soil to capture carbon from the air than usual.

“This could be a huge step when it comes to really (making) sure we’re directly reducing emissions for the city,” Beeler said.“Get involved. We really would love community participation with this, getting the word out, and really making sure everyone knows the good news about what’s actually happening in the city.”

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