When the University of California, Irvine (UCI) took stock of next-generation composting solutions several years ago, multiple options were on the table.
Investing in dehydrator and pulper units was eventually scuttled, for various operational reasons, in favor of a concept that takes composted food waste to biodigestion processing. It served as the ideal solution to develop the composting program and help establish a net-zero carbon footprint at the university.
A biodigester takes food scraps and other organic materials and breaks them down through the introduction of bacteria, which in turn releases methane gas through a process called anaerobic fermentation. The methane gas can then be used in the same way natural gas can. Any leftover solid waste can be used as fertilizer or composted again.
Biodigestion investments might at first seem like a lofty expense, but if executed via a community-shared program like UCI does, it can be cost-effective.
“You can do this (wet anaerobic digestion) really well if you have a lot of collaboration and cooperation. You don’t need a lot of money to make it work,” says Anne Krieghoff, solid waste and recycling coordinator at UCI, which became an active participant in composting tied to anaerobic digestion (AD) about nine years ago.
It began in 2010 with a small pilot and grew incrementally. These days, UCI feeds the AD beast 1,000 tons of composted waste per year. The process is carried out at a publicly owned Los Angeles-based facility through an agreement with waste hauler Waste Management Co.
Cost of entry
If the technology has the power to divert waste away from landfills, in turn creating energy in the form of electricity, natural gas and heat, then why isn’t everyone doing it?
One reason: A biodigester tank on a campus or in a hospital is a capital expense, requiring many noncommercial foodservice operations to scout third-party options.
The University of Michigan in Ann Arbor is performing its due diligence on a biodigestion food-waste initiative with the city of Ann Arbor, an effort that would allow the two entities to combine organic waste composite of approximately 110,000 tons—equating to roughly23,000 megawatt-hours (MWh) per year of renewable electricity generation. That would be enough to power approximately 2,211 homes for a year. The equipment would be housed at a neutral site.
For Keith Soster, director of student engagement for dining at the University of Michigan, it made little operational and economic sense for the university to invest in a proprietary, on-campus unit. One reason is that student attendance is greatly reduced in the summer months, and a biodigester would be subject to down time. In order for the unit to be fully optimized, it needs sustained, ongoing operation and a steady source of food, he says.
Broadly speaking, noncommercial composting has many success stories—with or without an investment in anaerobic biodigestion. But UCI and its dining and sustainability departments swear by its efficacy.
Krieghoff calls participation in biodigestion “a process change (to an organization) that is also the environmentally right thing to do.”
Under the agreement with Waste Management, the hauler routes composted food waste from the university’s 30 dining halls to an off-site slurry facility before transitioning to another location with digestion tanks.
Regardless of partnerships, there is a cost. UCI’s costs have shot up to $85 per ton to haul—or $35,000 a year—because all 30 dining facilities participate in the effort. Its annual composted food waste exceeds 1,000 tons, compared to 63 tons in 2011 that cost only $24 per ton to haul.
Some industry observers are proponents of biodigestion, but as a smaller piece of a broad food-waste reduction plan. At the top of the hierarchy is prevention. In 2015, preconsumer, noncommercial waste represented a $20 million savings opportunity per year, says Andrew Shakman, co-founder and CEO of Portland, Ore.-based Leanpath, a developer and marketer of software to help FSDs track and reduce waste. It’s now ballooned to $100 million a year.
“We don’t begrudge biodigestion, as it’s necessary to have a holistic strategy. But while we’re pro-anaerobic digestion, we’re all about prevention,” Shakman says.
Composting with biodigesters, pulpers and more is considered diversion that deals with food waste after it’s generated. “Prevention tools stop food waste from happening before it gets to the diversion stage. If you check the EPA’s food-waste hierarchy, prevention (or source reduction, as it’s called) is the most valuable solution to food waste, and the only one that delivers financial savings to kitchens and the biggest positive environmental impact,” Shakman says.
Investment paid dividends
UCI agrees that preconsumer waste prevention is a surefire way to reduce its 1,000 tons of annual food waste in the first place, and the university’s effort to stem that overall waste is a work in progress.
Dining hall waste accounts for 80% to 90% of all waste collected on campus, with student housing responsible for 10% to 20% at the 36,000-student university.
“Looking at our five-year plan, we are concentrating on waste minimization above and beyond waste diversion, and hopefully you will see that 1,000 tons per year of diverted waste being well-reduced because we won’t be producing as much,” says Lin Tang, director of dining services at UCI, citing better meal preparation planning.
But in addition to efforts to reduce any and all waste, all dining venues at UCI have composting bins positioned inside and out. Exterior bins range in size depending on the format. Interior bins range from 6 to 32 gallons depending on the food served and the size of the prep area. Preparing an omelet or stir-fry at the front of house warrants smaller, less obtrusive 6- to 12-gallon bins. Heavy-duty, back-of-house food prep calls for the larger 32-gallon bins, Krieghoff says.
All bins are fitted with plastic bags that collect up to 25 to 30 pounds of scraps at a time before they are tied and stacked in bins. At The Anteatery, UCI’s largest dining hall, a 2-yard bin sits outside, waiting for collection, while smaller branded locations such as Starbucks warrant a smaller, 64-gallon bin, because most waste consists of coffee grounds and snack foods.
Training, education are key
Krieghoff collaborates with Tang, as well as UCI dining’s sustainability coordinator, Lotus Thai, to ensure a seamless operation. This is essential because the Anteatery alone serves 8,000 meals per day. UCI has 150 full-time employees, 850 part-time student workers and 138 Aramark management employees.
“We assign ‘green captains’ to all locations, which is a student employee having some degree of affinity for sustainability,” Tang says. “Their job is to come up with ideas to make their dining location more sustainable, and to reduce the carbon footprint.”
UCI holds sustainability events during the year to unify the overall composting and waste-reduction effort of staff, facilities management, vendors and students. “We have found that when people are starving, sometimes their eyes are bigger than their tummies,” Krieghoff says.
Tang adds that UCI reduced per-guest waste to half an ounce, from an average of 1 ounce, by providing necessary reminders—with images—that food not eaten is wasted.
“It’s a wakeup call for some guests,” Tang says. “Many say, ‘Oh, I could have finished that banana.’ With anything edible, when a guest eats just a bite of pizza and disposes of it, we try and make them see the impact.”
Staff is trained to compost, so that whichever venue they may be assigned to work, they can make seamless adaptations—be it a proprietary dining hall or a Starbucks, Subway or Panda Express. “Say they come to a new location with different foods, like a pasta station,” Tang says. “We have pasta sauce packaged in large, round cans. They’re trained, so rather than pouring it out, they use a rubber silicon spatula to scrape it out and remove all sauce to be recycled.”
The University of Michigan doesn’t have an anaerobic digestion program, but that doesn’t minimize the level of training and education required to make composting a priority.
Michigan Dining operates 30 facilities that serve 24,000 meals per day, amassing food-waste diversion of 717 tons in 2018. Composted food is shipped to WeCare Organics, a local organization.
With 250 unionized staff and 100 full-timers, dining team members take part in two-hour training sessions known as “huddles,” with five team huddles planned per month. On campus, the two largest dining venues are South Quad and Bursley Hall. Both are mixed-use, combining dining and student living.
“We start our education initiative with freshmen, who get into the spirit of composting at the ground floor,” Soster says. When freshmen are indoctrinated into composting at an early stage on campus, those tendencies become habitual during sophomore year and beyond. At Bursley Hall, students are given a 1.5-gallon bucket that allows them to compost in their rooms on a small scale.
“We’re always looking at the low-hanging fruit for implementation,” Soster says. He referenced the university’s Planet Blue Ambassadors initiative for people interested in sustainability; they can become certified by completing a 45-minute online course. Planet Blue Ambassadors can consist of U-M faculty members, staff, students and alumnus.
While U of M’s current food diversion blueprint is succeeding, the university is seeking a higher level of macro-efficiency. Integration of anaerobic digestion is being scrutinized carefully.
Its sustainability goals are lofty: Using bio-digestion or other solutions, U-M is mandating a 40% reduction in waste tonnage that would be contributing to a goal of 25% emission reduction by 2025. It’s also aiming to produce 1,100 MWh of electricity, contributing to 0.2% of total U of M electricity use.
A biodigester could potentially be housed at the university’s Matthaei Botanical Gardens “or elsewhere central on campus to provide significant research potential for a closed loop renewable energy system,” according to a feasibility study conducted by the university.
U of M is looking at other universities that have implemented the process. Michigan State University in East Lansing has an anaerobic digester that processes 22,000 tons of organic waste per year, producing 2,800 MWh hours per year for campus buildings. The University of Wisconsin Oshkosh employs three digesters (an urban dry system converting 10,000 tons of waste per year to 3,300 MWh hours per year and supplying 8% of the university’s electrical needs). University of California, Davis’ digester converts 20,000 tons of waste per year to 5,800 MWh per year.
To add technology efficiencies to the equation, UCI implemented Leanpath’s software suite in 2018 and has realized significant reductions of pre- and post-consumer waste.
It’s also testing digital composting bins that inform guests how much waste they have disposed of after a meal, Tang says. “When a guest throws something away into the bin, a message pops up on the screen informing them how much was wasted. A scale is also attached to weigh the food that’s been wasted,” she says.
Ultimately, the fundamentals of food waste and the overarching sustainability principles will net the most positive outcomes. To nip waste in the bud during ordering, U of M has done what many universities have also tried, which is rolling out small, tapas-style plates as menu items to minimize waste, as well as giving diners the ability to custom-order foods—think a turkey burger minus the bun.
“We’re trying to get people to monitor their consumption habits, and all this has helped on the road to sustainability,” Soster says, adding that simply embossing compostable plates and cups with the word “compostable,” plus images and signage, can steer guests to make more prudent disposal decisions.
At UCI, which is at the leading edge of sustainability, directors work hard to ensure that external partners have full buy-in to their sustainability plan. Dialogue is essential so that all branded concepts, employees and suppliers are pulling in one direction, Tang says.
“Jamba Juice has been using Styrofoam cups, so we had to let them know we don’t carry that type of vessel. We engaged with a vendor that sells gourmet tea, but in plastic bottles. We love their tea but asked if they could produce a new, sustainable package,” Tang says. “So they are working on a paper bottle package. They would not have known that had we not said anything.”